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1
Sindelar, Pavel J. "Hepatic lipase and dolichol esterification /". Stockholm, 1997. http://diss.kib.ki.se/1997/91-628-2772-3.
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Al-Seeni, Madeha N. "Control of hepatic cholesterol esterification". Thesis, University of Nottingham, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293154.
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Hatcher, Stuart Dominic. "Tin promoted lactonisation and esterification reactions". Thesis, King's College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391799.
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Lindmark-Henriksson, Marica. "Biotransformations of Turpentine Constituents : Oxygenation and Esterification". Doctoral thesis, KTH, Chemistry, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3529.
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This thesis describes methods to obtain valueaddedcompounds from TMP-turpentine obtained from the spruce, Piceaabies. The methodology focuses on biotransformations using twoapproaches: an oxygenation approach (i.e. oxygenation ofterpene hydrocarbons by cell cultures) and an esterificationapproach (i.e. lipase-catalysed transesterification of vinylacetate with terpene alcohols, and a further fractionation ofthe TMP-turpentine).
The main constituents of the turpentine, a-pinene, b-pineneand limonene, were subjected to a P. abies suspension culture.Allylic oxidation formed the major products for α-pineneand β-pinene, which were further oxidised to theirrespective aldehyde or ketone. One of the minor products froma-pinene, cis-verbenol, was not only transformed into verbenonebut also isomerised to trans-verbenol. Limonene gavelimonene-(1,2)-epoxide as the major product.
Fractionation of monoterpenes is accomplished throughphysical separation methods, chromatography and distillation,and lipase-catalysed transesterification of vinyl acetate withterpene alcohols. The esters of myrtenol and trans-pinocarveolwere separated from the more slowly reacting alcohols such asborneol and carveol by use of a combination of the Mucor mieheilipase and Candida antarctica lipase A as catalysts.Furthermore, the non-reacting tertiary terpene alcohols wereseparated from the reacting alcohols in a single step byCandida antarctica lipase A.
Lipase-catalysed (Candida antarctica lipase B andPseudomonas cepacia lipase) transesterification of vinylacetate with sterically hindered secondary alcoholsunexpectedly yielded hemiacetals or hemiacetal esters. Thereaction conditions required to obtain these side products havebeen studied.
Keywords:Picea abies, Pinaceae, Essential oilscomposition; Terpene alcohol; Hemiacetal; Hemiacetal ester,TMP-turpentine; Monoterpene; α-Pinene; β-Pinene;Limonene; Verbenol; Pinocarveol; Borneol; Myrtenol; Suspensioncell culture; Biotransformation; Lipase-catalysed; Oxidation;Allylic oxidation; Transesterification; Autoxidation;Separation.
5
Bankole, Kehinde Seun. "Uncatalyzed esterification of biomass-derived carboxylic acids". Diss., University of Iowa, 2011. https://ir.uiowa.edu/etd/922.
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To shift from a petroleum-based to a biomass-based economy will require the development not only of biofuels, but also of biorenewable replacements for petroleum-derived chemicals. In this regard, environmentally friendly biomass-derived esters may serve as alternatives to fossil-derived chemicals such as toxic halogenated solvents and glycol ethers. Therefore, esterification of various carboxylic acids that find significant applications in the chemical, pharmaceutical, petrochemical, food, and cosmetic industries has been initiated by the chemical industry.
At atmospheric condition, esterification is a reversible reaction limited by the low equilibrium conversion and slow reaction rate, and has recently been performed with excess alcohol to shift the equilibrium conversion. Heterogeneous or homogeneous acid catalysts are used to achieve acceptable reaction rates. The conventional acid-catalyzed process has been extensively developed; but it suffers from problems associated with the generation of side reactions, corrosion of equipment, expensive purification procedures, long reaction times and discharge of acidic wastes. Various attempts on esterification of carboxylic acids with ethanol have previously addressed important issues concerning product distribution, catalyst activity, and kinetics of acid-catalyzed esterification at lower reaction temperatures, but kinetics of uncatalyzed esterification at elevated reaction temperatures are still very limited. It is thus of great interest from a practical viewpoint that more information such as kinetic and thermodynamic parameters are required to develop a possible esterification process without using any catalyst.
In this work, therefore, a fundamental study on the uncatalyzed esterification of different aliphatic carboxylic acids with stoichiometric amounts of ethanol was undertaken to examine the possibility of converting the biomass-derived carboxylic acids to ethyl esters and to determine the kinetic and thermodynamic parameters for the uncatalyzed esterification. Experiments were conducted with isothermal batch reactors at temperatures ranging from 298 K to 623 K. A 2nd-order reversible kinetics rate expression was used to fit the experimental data. The thermodynamic and kinetic values estimated were found to vary for different esterification systems studied. The dependence of Keq on temperature for esterification of short-chain and long-chain carboxylic acids varied. Despite the nonlinearity of the Van't Hoff plot for esterification of linoleic acid, the Arrhenius and Eyring plots were linear. Two thermodynamic paths were developed for estimating the equilibrium conversions, and the theoretical values compared well with the experimental results reported in this study.
Additional experiments performed to assess the corrosive and catalytic influences of metallic materials on esterification reaction indicated Inconel 625 alloy, nickel wire and stainless steel materials have potential corrosion problems on the uncatalyzed esterification reaction at elevated reaction. However, tantalum and grade 5 titanium materials showed acceptable level of compatibility for similar reaction conditions, and this can encourage the design of a flow reactor system.
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MAININI, FRANCESCA. "ESTERIFICATION OF NATURAL COMPOUNDS WITH FATTY ACIDS". Doctoral thesis, Università degli Studi di Milano, 2012. http://hdl.handle.net/2434/170495.
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In this PhD project we dealt with β-sitosterol, resveratrol and quercetin, three natural substances featuring ascertained biological activities. These compounds are characterized by a limited bioavailability and a low stability: these features reduce their application in pharmaceutical, nutraceutical and dermocosmetic areas. In order to improve the above mentioned properties, we synthesized esters of these compounds, following either a chemical approach (resveratrol, quercetin, and β-sitosterol) and a enzymatic approach (resveratrol and β-sitosterol). The esterification was performed with saturated (palmitic and stearic) and unsaturated (oleic, linoleic and linolenic) fatty acids: this synthesis introduced in a single molecule (prodrug) two moieties both pharmacologically active.
Chemical synthesis was used to obtain resveratrol triesters, but failed with diesters: so these derivatives were synthesized by enzymatic approach. 1H-NMR and 13C-NMR analyses allowed to define the structure of these derivatives.
The synthesis of quercetin penta, tetra and triesters was obtained by modulating the acid/quercetin molar ratio; mono- and bi-dimensional NMR techniques were used to determine the structure of all quercetin esters, while for triester computational studies were needed.
In addition, for resveratrol and quercetin esters the antioxidant activity was evaluated: this property was not increased by esterification. Also the bioavailability was studied for resveratrol and its trioleoyl ester, but the resveratrol resulted more bioavailable in comparison with its ester.
In order to improve drug topical delivery, quercetin and its derivatives were also incorporated in liposome formulations.
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Lee, Sun Min. "Studies of the Mechanism of Plasma Cholesterol Esterification in Aged Rats". Thesis, University of North Texas, 1989. https://digital.library.unt.edu/ark:/67531/metadc331051/.
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The study was performed to determine factors influencing the esteriflcation of plasma cholesterol in young and aged rats. The distribution of LCAT activity was determined following gel nitration chromatography and ultracentrifugation of whole plasma respectively. When rat plasma was fractionated on a Bio-Gel A-5 Mcolumn, LCAT activity was found to be associated with the HDL fraction. A similar result was observed upon 24 hr density gradient ultracentrifugation of the plasma. However, following prolonged 40 hr preparative ultracentrifugation, the majority of the LCAT activity was displaced into the lipoprotein-free infranatant fraction (d> 1.225 g/ml). The dissociation of LCAT from the HDL fraction occured to a smaller extent in aged rat plasma than in young rat plasma. Plasma incubation (37°C) experiments followed by the isolation of lipoproteins and the subsequent analysis of their cholesterol content revealed that in vitro net esteriflcation of free cholesterol (FC) by LCAT as well as the fractional ufilization of HDL-FC as substrate were lower in the plasma of the aged animal as compared to that of the young animal despite the fact that the total pool of FC was higher in the former. The net transfer of FC from lower density lipoproteins (d<1.07 g/ml) to HDL provided the FC (in addition to HDL-FC) for esteriflcation in the plasma of both young and aged rats, and this process was not substantially affected by aging. Substrate specificity studies indicated that HDL from young rats was a better substrate for LCAT than the HDL from aged rats. The HDL isolated from the plasma of aged rats was enriched with apo E and had a considerably higher molecular weight than the HDL from young rat plasma. The ratio of phosphatidyl choline/sphingomyelin was lower in the HDL of aged rats. These data suggest that the decreased plasma cholesterol esteriflcation in aged rats is due to changes in the composition and size of the lipoprotein substrate (HDL).
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Matsumura, Hiroyuki. "Efficient Utilization of Biomass through Esterification of Cellulosics". Kyoto University, 2003. http://hdl.handle.net/2433/148642.
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Kyoto University (京都大学)0048
新制・課程博士
博士(エネルギー科学)
甲第10324号
エネ博第60号
新制||エネ||19(附属図書館)
UT51-2003-H745
京都大学大学院エネルギー科学研究科エネルギー社会・環境科学専攻
(主査)教授 坂 志朗, 教授 牧野 圭祐, 助教授 河本 晴雄
学位規則第4条第1項該当
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Dastjerdi, Zahra. "The Esterification of Naphthenic Acids for Methyl Ester Production". Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/28802.
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The remediation of tailings water, a by-product of bitumen extraction, is of utmost importance to the Athabasca oil sands industry due to its toxicity to aquatic environments. Naphthenic acids (NAs), natural components of bitumen, are the major contributor to the toxicity of tailings water. The use of algae for remediation of tailings water is a new approach to reduce the toxicity of tailings water. The combined extracted NAs and algal oils can potentially be used as a low cost feedstock for the production of biodiesel. In this study, the feasibility of using NAs for the production of biodiesel was investigated using mixtures of canola oil and commercial NAs as model compounds.
Since NAs are a mixture of cyclic and acyclic carboxylic acids, the acid-catalyzed esterification of NAs without canola oil was investigated. The acid-catalyzed esterification reaction was carried out with methanol, and the influence of variables affecting the esterification process was examined. The experimental results showed that increasing temperature and catalyst concentration increased the reaction rate and final conversion of NAs to their corresponding methyl esters. The catalyst study showed that sulfuric acid had a more positive effect on the esterification reaction compared to p-toluene sulfonic acid. Additionally, an excess methanol:oil ratio had a negative effect on the esterification reaction due to the solubility of NAs in methanol.
The acid-catalyzed transesterification/esterification of mixtures of NA and vegetable oil (canola oil along with 5% NAs) with methanol was investigated at different operating conditions. The outcomes of these experiments showed that increasing temperature, sulfuric acid concentration, and methanol content had positive effects on the rate of reaction and final ester products.
The general conclusion of the thesis is that the conversion of NAs to useful products is indeed feasible and can be part of the solution to tar sands tailing pond remediation.
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Levesque-Tremblay, Gabriel. "Pectin methyl esterification functions in seed development and germination". Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/46351.
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Lindmark, Johanna. "Evaluation of Esterification as a Valorization Route for Oxidized Lignin". Thesis, Luleå tekniska universitet, Industriell miljö- och processteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-66306.
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RISE Bioeconomy is working with the biorefinery concept. That is, for the company, to utilize all wood derivatives in effective processes, resulting in unique products. RISE Bioeconomy is investigating the possibilities of producing holocellulose through an oxidative delignification process of wood, using peracetic acid (PAA). The product, high-purity holocellulose, can be used for the production of for example cellulose nanofibers, a product that in recent years have increased in interest. The PAA-delignification process relies on oxidative treatment with peracetic acid, where the lignin is solubilized in water through the formation of carboxylic groups in the lignin, yielding cellulose of very low lignin content and minimal degradation of the cellulose. In addition to the holocellulose, a solution containing water, acetic acid, salts and highly oxidized lignin is obtained. The PAA-delignification has yet only been performed in lab-scale, however, the aim is to scale up the process. There has not yet been any further utilization of the oxidized lignin and it has been proposed that esterification of the carboxylic groups with an alcohol is a possible valorization route. Due to the up-scaling of the PAA-delignification, it is of large interest to find a valorization route for the lignin by-product to fulfill the biorefinery concept. This master thesis focuses on evaluating esterification of an oxidized lignin, with the aim to propose a process suitable for up-scaling. The lab trials for the PAA-delignification of wood yielded limited amounts of lignin and due to difficulties while isolating this lignin, it was not partially characterized until months into the project. Therefore, model compounds were initially used to evaluate the process setup. Compounds with muconic acid type structures are some of the expected products from PAA-delignification of wood and muconic acid was therefore used as a model compound. In addition to this, vanillic acid was used to represent the phenolic lignin compounds. Gas Chromatography/Mass Spectrometry (GC/MS) analysis of the vanillic acid esterification was shown to be a suitable method for analyzing the conversion of this reaction. Due to the difficulties with the analysis of the model compounds, no results regarding the reaction procedures were obtained. As a “proof-of-concept”, a kraft lignin was oxidized, isolated and then esterified. Two different methods of esterification were performed, with and without a molecular sieve. It was assumed that the amount of carboxylic groups would increase after oxidation and decrease after a successful esterification. The amount of carboxylic groups after each process was analyzed with Phosphorus Nuclear Magnetic Resonance (31P-NMR). For the process without molecular sieve, the 31P-NMR analysis indicated that esterification of the lignin had occurred, to a limited extent. This was confirmed by Fourier Transform Infrared Spectrometry (FTIR). The process with molecular sieve showed no indication of esterification of the lignin. The project did prove the concept of esterifying an oxidized lignin and led to several different proposals for further work in the area. Due to the very wide scope of this project and several unexpected obstacles, this project did not fully answer the research questions given.
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Nguyen, Van Chuc. "Catalytic production and esterification of aqueous solution of lactic acid". Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1136.
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Cette thèse porte sur la production d'acide lactique par conversion de la biomasse lignocellulosique catalysée par des acides de Lewis solides dans l'eau puis l'estérification d'acide lactique aqueux avec de l'éthanol. La conversion de la cellulose est étudiée en autoclave, en utilisant comme catalyseurs, de la zircone et de l'alumine contenant du W ou Sn (ZrW, AlSn) et différents hydroxydes métalliques. L'étude de la conversion de la cellulose en acide lactique en présence de ZrW non calcinée, ZrW calcinée, Zr(OH)4 et ZrO2, montre que la phase active du catalyseur est constituée de Zr4+, les centres acides de Lewis et de groupes hydroxyles. Les performances catalytiques des catalyseurs AlSn, préparés à partir de chlorure d'étain comme précurseur, dépendent fortement de la présence résiduelle de chlorure, ce qui favorise la formation d'acide lévulinique. Les hydroxydes de certains métaux de transition se sont révélés être des catalyseurs solides efficaces pour la conversion de la cellulose en acide lactique. Il a été observé que le rendement en acide lactique dépend de la concentration et de la basicité des groupes OH superficiels des hydroxydes de métaux de transition et de la présence de sites acides de Lewis. L'estérification de l'acide lactique, à différentes concentrations en l'eau, a été étudiée en présence d'Amberlyst 15, de charbon sulfoné et d'oxyde de graphène pour étudier l'activité et la tolérance à l'eau de catalyseurs solides acides à base de carbone. Il est montré, par calorimétrie d'adsorption d'ammoniac, que l'oxyde de graphène présente des sites superacides et qu'il conduit à la plus grande activité et tolérance à l'eau. L'augmentation de la teneur en eau montre un fort effet inhibiteur sur l'activité du charbon sulfoné alors que d'Amberlyst 15 et l'oxyde de graphène sont plus tolérants. Les catalyseurs ne sont pas stables dans des conditions d'estérification, en présence d'eauThis thesis reports the synthesis of lactic acid from lignocellulosic biomass catalyzed by solid Lewis acid catalysts in water and then esterification of aqueous lactic acid solutions with ethanol. The cellulose conversion was tested in autoclave, in hot water, using zirconia and alumina containing W or Sn (ZrW, AlSn) and different solid metal hydroxides. The conversion of cellulose to lactic acid using uncalcined ZrW, calcined ZrW, Zr(OH)4 and ZrO2 shows that the active surface of the catalyst consists of Zr4+ Lewis centers and OH groups. The catalytic performances of AlSn catalysts, prepared from Sn chloride as precursors, strongly depend on the residual amount of chloride which favors the formation of levulinic acid. Some hydroxides of transition metals were disclosed as efficient solid catalysts for the conversion of cellulose to lactic acid. The yield of lactic acid was observed to depend on the concentration and the basicity of the superficial OH groups and on the presence of Lewis acid sites. The esterification of lactic acid, at different concentrations in water, was studied using Amberlyst 15, sulfonated carbon and graphene oxide to evaluate the activities and water tolerance of carbon based solid catalysts. Graphene oxide, shown by calorimetry of NH3 adsorption to exhibit super-acid sites, leads the highest activity and water tolerance. Increasing amounts of water has a strong inhibiting effect on the activity of sulfonated carbon and less influence on activity of Amberlyst 15 and graphene oxide. However, all catalysts were not stable in esterification conditions, in presence of water
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Sergeant, Claire. "Esterification d'acides gras tissulaires par l'éthanol : influence des lipides alimentaires". Bordeaux 1, 1991. http://www.theses.fr/1991BOR10588.
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La consommation abusive d'alcool entraine des lesions hepatiques mais aussi cardiaques et cerebrales qu'on ne peut expliquer par le metabolisme oxydatif principal de l'ethanol. Pour mieux comprendre l'origine de ces atteintes extra-hepatiques, une voie secondaire de degradation de l'ethanol: l'esterification des acides gras tissulaires, a ete etudiee. Dans les serums de malades alcooliques, des ethyl esters d'acides gras ont ete mis en evidence. L'analyse de tissus: foie, cur, cerveau, d'animaux alcoolises par inhalation a permis de tester l'incidence de la composition lipidique du regime alimentaire sur la formation des ethyl esters d'acides gras tissulaires
14
Phalak, C. A. "Reaction engineering studies in ion exchange resin catalyzed esterification reactions". Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2004. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2877.
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Thompson, Judith U. S. "Investigation of pervaporation enhanced enzymatic esterification of geraniol to geranyl acetate". Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/10140.
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Porter, Altic Lucas Eli. "Characterization of the Esterification Reaction in High Free Fatty Acid Oils". Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3582.
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Energy and vegetable oil prices have caused many biodiesel producers to turn to waste cooking oils as feedstocks. These oils contain high levels of free fatty acids (FFAs) which make them difficult or impossible to convert to biodiesel by conventional production methods. Esterification is required for ultra-high FFA feedstocks such as Brown Grease. In addition, ultrasonic irradiation has the potential to improve the kinetics of the esterification reaction. 2-level, multi-factor DOE experiments were conducted to characterize the esterification reaction in ultra-high FFA oils as well as determine whether ultrasonic irradiation gives any benefit besides energy input. The study determined that sulfuric acid content had the greatest effect followed by temperature and water content (inhibited reaction). Methanol content had no effect in the range studied. A small interaction term existed between sulfuric acid and temperature. The study also concluded that sonication did not give any additional benefit over energy input.
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Mazza, Mathieu. "Modification chimique de la cellulose en milieu liquide ionique et CO2 supercritique". Phd thesis, Toulouse, INPT, 2009. http://oatao.univ-toulouse.fr/7832/1/mazza.pdf.
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L'estérification de la cellulose a été réalisée dans deux milieux non-conventionnels. D'un coté, Le CO2 supercritique a permis l'obtention d'esters de cellulose à très faible degré de substitution (DS) en milieu hétérogène. D'un autre coté, les liquides ioniques utilisés ont permis de réaliser l'estérification de la cellulose en milieu homogène et d'obtenir des composés avec un large choix de DS. Parmi ces liquides ioniques, le BMIMCl a conduit à la formation d'ester gras de cellulose à faible DS et avec un caractère thermoplastique innovant. Le deuxième liquide ionique utilisé, découvert grâce à une étude turbidimétrique mise au point lors de ce travail de thèse, a permis d'obtenir des esters gras de cellulose à fort DS dans des conditions opératoires douces.
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Pabai, Franknel Sandi Kouvea. "Production, purification, characterization of selected microbial lipases and their application for interesterification of butter fat". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0005/NQ30354.pdf.
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Safari, Mohammad. "Interesterification of butter fat by commercial microbial lipases in organic solvent media". Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41762.
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The interesterification yield (IY) and changes in fatty acid positional distribution of selected butter fat triacylglycerols were investigated, using a wide range of commercial microbial lipases and organic solvent media. The interesterification of butter fat by lipase from Mucor miehei was carried out in hexane, hexane-chloroform, and hexane-ethyl acetate; the results showed that the addition of 30% of either chloroform or ethyl acetate to the hexane resulted in a 23% increase in the IY. The interesterification of butter fat in a microemulsion co-surfactant system, containing Brij 35 as surfactant and 1-heptanol as co-surfactant, resulted in an increase in the triacylglycerols that contain C18:0 at sn-2 position, located originally at sn-1,3 positions, with a concomitant interchange with C14:0 and C18:1 at the same position. The interesterification of butter fat by lipase from Rhizopus niveus, in a phosphatidylcholine reverse micellar system, showed an increase in C16:0 at the sn-2 position, with a concomitant decrease in the proportion of small chain fatty acids (C4-C10:0); however, the interesterification of butter fat in co-surfactant free microemulsion systems, containing hexane and ionic (phosphatidylcholine) and non-ionic (sorbitol monostearate and polyoxyethylene sorbitan monostearate) surfactants, showed that the interesterified selected triacylglycerols were enriched with C18:0 and C18:1, originally located on sn-1,3 position, at sn-2 position with concomitant interchange with C12:0, C14:0 and C16:0, originally located at the same position. The interesterification of butter fats, in co-surfactant free microemulsion system, by four microbial lipases showed that those catalyzed by lipase from R. niveus demonstrated a 46% increase in the proportion of C18:1 at sn-2 position whereas those catalyzed by enzymes from M. javanicus, R. delemar and M. miehei were enriched with C16:0 at the same position, by 21%, 35% and 41%, respectively. In addition, lipase from
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Wilson, Diane Lilias. "Lipoprotein oxidation and the cholesterol esterification in a human monocytic cell line". Thesis, University College London (University of London), 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309473.
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Teo, Hue Tat Ronnie. "Recovery of dilute acetic acid through esterification in a reactive distillation column". Thesis, Loughborough University, 2005. https://dspace.lboro.ac.uk/2134/24561.
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With ever-growing environmental concerns, petrochemical and fine chemical industries face an omnipresent issue in recovering acetic acid from its aqueous solutions. The recovery of acetic acid through the esterification process is a very viable option. However, esterification reactions are typically restricted by equilibrium limitations, and face challenges with product purification. Reactive distillation is an emerging technology that has an extremely attractive potential as a process alternative for carrying out equilibrium limited chemical reactions. Although the reactive distillation process has been successfully commercialised for the manufacture of hIgh commodity chemicals e.g. methyl tertiary butyl ether (MTBE) and methyl acetate, its potential as a separation tool for the recovery of acetic acid using iso-amyl alcohol has not been exploited.
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Sattenapally, Narsimha. "SYNTHESIS AND DEVELOPMENT OF SILICON ANALOG OF FLUORESCEIN FLUOROPHORES AND ESTERIFICATION CATALYSTS". OpenSIUC, 2012. https://opensiuc.lib.siu.edu/dissertations/588.
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The synthesis and development of new materials and the improvement of the existing materials are a continuous quest for scientists. There is a constant need for new materials that have more advantages over the existing ones. The research to develop new materials can be appreciated in high magnitude, as the new materials improve the livelihood. In this dissertation, we are presenting our progress in developing new materials, such as fluorescence fluorophores as probes, and esterification catalysts. In the first part of the dissertation, the synthesis and characterization of a novel silicon analog of fluorescein (silyl fluorescein) was studied in detail. The photo-physical properties and toxicity studies of these fluorophores are also discussed. Compared to fluorescein, silyl fluorescein displayed a 90 nm longer wavelength in its absorption and emission. Silyl fluorescein showed good solubility in water and organic solvents, and has a considerable fluorescence quantum yield compared to fluorescein. Silyl fluorescein was found to be moderately toxic under light and non-toxic in dark, where as fluorescein toxicity was found to be greater than silyl fluorescein both in the dark and under light. Two probes from our novel silyl fluorescein fluorophore were developed and studied. SIF HySOx is probe for hypochlorous acid (HOCl), which is a reactive oxygen species (ROS) found in cells that are stressed due to various diseases. The HOCl probe was synthesized and its photo-physical properties were studied. It was found to be selective and sensitive only to HOCl. A fluoride probe (DTBDMS SIF P) was also developed from silyl fluorescein. Its synthesis and photo-physical properties were also studied. The probe displayed excellent selectivity and sensitivity to fluoride (TBAF) in the presence of other halides and bases. Future directions on novel fluorophore are briefly mentioned. Second part of the dissertation is focused on the screening of two organic esterification catalysts which were synthesized by Dr. Liu and Dr. Wong. The catalysts which are synthesized from pyridine and dinitrobenzene moieties were screened with several carboxylic acids and alcohols. Catalyst 8-4 was shown to be moderately active in the esterification of carboxylic acids and alcohols. It has no selectivity in the esterification of primary, secondary, tertiary alcohols, and the carboxylic acids that are attached to those carbons. Catalyst 9-1 however, was more efficient in the esterification of carboxylic acids and alcohols. Catalyst 9-1 displayed selectivity in the esterification of primary, over secondary, over tertiary alcohols, and the carboxylic acids that are attached to those carbons. Catalyst 9-1 gave up to 95% isolated yields.
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Tibbits, C. William. "Studies on the pectin network of the tomato fruit cell wall". Thesis, University of East Anglia, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327392.
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Camp, David. "Some Aspects of the Mitsunobu Reaction". Thesis, Griffith University, 1990. http://hdl.handle.net/10072/366203.
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A 31P NMR based study of the Mitsunobu esterification reaction has been undertaken. Three intermediates have been identified: an alkoxytriphenyiphosphonium carboxylate, a dialkoxytriphenyiphosphorane and an (acyloxy)alkoxytriphenylphosphorane. These three species are in equilibrium with each other, the position of the various equilibria depending on the polarity of the solvent, pKa of the acid and structure of the alcohol. Given the choice between a primary and secondary alcohol, only the phosphorane and oxyphosphonium salt corresponding to the primary alcohol are observed. The implications of these findings for the regioselectivity and stereoselectivity of the Mitsunobu reaction are discussed. Formation of the phosphonium salt is facilitated in more polar solvents or with acids of low pKa. The chemical shift of the alkoxyphosphonium carboxylate was found to be extraordinarily sensitive to the presence of proton sources and solvent, varying over a range of more than 100 ppm. The peripatetic nature of this species has been interpreted in terms of a rapid equilibrium between the alkoxytriphenylphosphonium carboxylate and the corresponding (acyloxy)alkoxytriphenylphosphorane. Substitution of triphenylphosphine by tributylphosphine using otherwise standard Mitsunobu protocol revealed clean formation of a single intermediate, the alkoxyphosphonium carboxylate. In the absence of acid, at least two species were observed, a dialkoxyphosphorane and an alkoxyphosphonium alkoxide salt. Replacement of iriphenylphosphine by 9-phenyl-9-phosphafluorene confirmed that betaine formation was irreversible and proceeded via a nucleophiic addition, not a cheleotropic mechanism. Modification of triphenylphosphine by incorporation of an alcoholic or acidic moiety into the structure allowed detection of a possible O,Nphosphorane, an intermediate previously postulated in the Mitsunobu reaction. The synthesis of a series of bulky phosphines showed that steric congestion about the phosphonis atom retarded the rate of betaine (and particularly) phosphorane formation. An EPR based study has revealed for the first time that radicals are formed during the reaction of phosphines with azodicarboxylates. Evidence is presented to suggest that the betaine arising from this reaction may be formed via a single electron transfer pathway.
The reaction of diphenylphosphine and of diphenylphosphine oxide with azodicarboxylates is examined. Diphenylphosphine reacts surprisingly sluggishly, whereas diphenyiphosphine oxide reacts rapidly to give the expected addition product. An 'abnormal' Mitsunobu-like reaction involving catalytic amounts of triphenylphosphine in the presence of diisopropyl azodicarboxylate and a,co-dithiols to afford disulfides has been studied. The mechanism is discused in terms of expulsion of triphenyiphosphine from either an S,S-dithiophosphorane or thiophosphonium thiolate salt. The substitution of a,w-dithiols by a,w-mercaptoalcohols was also briefly examined. Finally, diphenyl(2-pyridyl)phosphine was used in place of triphenylphosphine for those Mitsunobu reactions where removal of wiphenylphosphine oxide is difficult or troublesome.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Division of Science and Technology
Science, Environment, Engineering and Technology
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Chacon, Micaela. "Esterification as a strategy for the detoxification of value compounds in Escherichia coli". Thesis, University of Bath, 2017. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760939.
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The use of microbial platforms for the production of commercially valuable compounds has grown over the last few decades as concern over the sustainability of other production methods, such as extraction and chemical synthesis, has been come into question. Advancements in the understanding of microbial metabolism and regulation with the aid of -omics research, and a steady increase in the number of available genetic tools, has allowed model organisms such as the bacteria Escherichia coli and the yeast Saccharomyces cerevisiae to be engineered for high titre production of a number of value products. The economical production of these compounds on an industrial scale can, however, be hampered by the toxicity of a given end-product upon accumulation in culture. The mode of action by which these products interfere with cellular homeostasis is often multifaceted, making it difficult to address. As such, considerable research has gone into developing strategies to minimize this microbial toxicity in platform hosts; including engineering strains for increased tolerance, and the development of fermentation strategies for the in situ removal of toxic end-products. These efforts have had mixed success, with the microbial titres of a number of value compounds continuing to be limited due low tolerance thresholds of the host. In this work, an alternative strategy for minimizing the toxicity of value alcohols in E. coli was investigated. This strategy involved the in vivo sequestration of an endogenously produced alcohol into a more neutral short/medium chain ester via enzyme mediated esterification by an alcohol acyl transferase (AAT). The rationale behind this strategy being that the incorporation of a toxic alcohol into a less toxic ester molecule may facilitate higher product accumulation in culture, as the ester end-product would be minimally inhibitory. Further, the alcohol component of the ester could be easily recovered downstream through hydrolysis, while the recovered acid component could be recycled as substrate for this strategy in future cultures. In this work, the feasibility of this detoxification strategy was first validated and then applied to two commercially valuable alcohols in E. coli. The first alcohol to which this strategy was applied was the proposed gasoline alternative short chain alcohol, butanol, which is detrimental to culture health when present at concentrations above 1.5% (v/v); and the second alcohol trialled was the common flavour and fragrance constituent monoterpene alcohol, geraniol, which is inhibitory when present above 0.05% (v/v) in culture.
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Gumaste, V. K. "Application of zeolite catalysts in esterification, ritter reaction and alkylation of aromatic substrates". Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 1995. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2798.
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富洵 i Xun Fu. "Lipase selectivity in reactions involving natural and synthetic fatty acids and fatty alcohols". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B3124015X.
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Venzon, Simoni Spohr. "Physical and chemical properties and antioxidant activity of modified and unmodified pectins extracted from orange bagasse". Universidade Tecnológica Federal do Paraná, 2013. http://repositorio.utfpr.edu.br/jspui/handle/1/1130.
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Modified pectin is a polysaccharide rich in galacturonic acid altered by pH adjustment and thermal treatment used especially as an anti-cancer agent. The aim of this work was to study the physical and chemical properties of modified and unmodified pectins extracted from orange bagasse by using citric and nitric acids. The galacturonic acid content, degree of esterification, Fourier Transform Infrared 30 Spectroscopy profile, molar mass, intrinsic viscosity, rheological properties and antioxidant activity of the pectins were evaluated. The modification process caused the de-esterification of pectins, responsible for improving the intestinal absorption of modified pectin and a decrease of molecular weight due to removal of neutral sugars, maintaining the linear chain of galacturonic acid. Such changes also caused a significant increase in the in vitro antioxidant activity and influenced the rheological properties of pectin, reducing its viscosity. This work showed that the modification of pectin from orange bagasse with citric and nitric acids altered its structural and physical characteristics as well as its biological activity toward a free-radical, suggesting that some functional properties related to antioxidant activity activity and absorption of nutrients may be increased.
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Chiu, Li-Chun, i 邱麗君. "Protease catalyzed esterification". Thesis, 1994. http://ndltd.ncl.edu.tw/handle/73099123030276174106.
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葉遠平. "Development of Esterification Catalyst". Thesis, 2001. http://ndltd.ncl.edu.tw/handle/00798097574843762539.
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碩士國立中正大學
化學工程研究所
89
Abstract In early study, we found that ethyl-acetate can be formed directly from water-containing ethonal(5%H2O) with Pd/SDB (Styrene divinyl benzene compolymer) catalyst. However, because of the low affinity between metal clusters and hydrophobic support, the catalyst deactivated rapidly by the extraction of Pd(CH3COO)2, which is formed from the reaction of palladium with acetic acid, a byproduct and intermediate of the reaction. Since the water adsorption can greatly be decreased by hydrophobic catalyst, combined Amberlyst 35 with Pd/SDB was thus be used. It’s have several problems like metal aggregating, low eaterification selectivity etc. Besides, Amberlyst 35 is a polymer which has low heat resistance and hardly regenerition. To remedy the drawbacks of the catalysts, zeoilte-supports bimetallic catalysts Pd-X(Pt, Ag, Ni)/Zeolite have been developed. By controlling operation conditions ,we wish to get the goals of high esterification selectivity, stability maintenance, and low ipurity. The major study is (1)The influence of Si(silicon)/Al(aluminum) ratio of the Zeolite catalyst to esterification reaction: Si/Al ratio will be effect to acidity strength of Zeolite catalyst to make differ to ability of esterificaton reaction. When Si/Al ratio becomes higher, the acidity becomes stronger and the ability of esterification reaction becomes better. But the catalyst will produce too few acid to proceed the esterification reaction. (2) Temperature factor: When reactant changes from liquid phase to gas phase, the ethanol conversion will raise 10% by using the catalyst prepared by our lab. (3) O2 /ethonal ratio: The reaction will be best in a specific range of ratio. If the ratio of O2 /ethonal is too high, the selectivity to fuel gas and acetic acid will be increase. Otherwise the can’t react completely and selectivity to acetaldehyde will increase.(4) Character of catalysts: By experiment, the result of reaction in fixed bed reactor is the same with catalytic distillation. It show that our catalyst will have quality of catalytic distillation. Now we change temperature, pressure and feed ratio to find best operation conditions. In the future, we hope we can be promising for industrial application.
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Watkins, Jacinta. "Understanding carotenoid esterification in cereals". Phd thesis, 2019. http://hdl.handle.net/1885/186942.
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Carotenoids are important micro-nutrients for humans present in fruits, vegetables and certain grains including bread wheat (Triticum aestivum). Several carotenoids including beta-carotene and beta-cryptoxanthin provide provitamin A activity, whilst xanthophylls, including lutein and zeaxanthin, are essential for ocular and brain development, maintenance of cognitive function in elderly, as well as important for the prevention of a range of degenerative diseases including age-related macular degeneration. The health benefits provided by carotenoids makes them key targets regarding biofortification of staple foods. However, due to their reactive nature, carotenoids are highly prone to oxidative degradation and have rapid turnover during the storage of crops, both in common varieties and biofortified lines. In commonly consumed foods carotenoids are often found esterified with fatty acids. Esterification positively influences stability, sequestration and accumulation of carotenoids. However, whilst the genes and regulation of carotenoid biosynthesis have been well studied, the molecular mechanisms underpinning esterification have remained unknown in all plant species to date.
This thesis presents data on the identification and genetic and biochemical characterisation of Xanthophyll Acyl-Transferase (XAT), a member of the GDSL esterase/lipase gene family, responsible for the production of carotenoid esters in mature grain of bread wheat. Using heterologous expression systems, it is demonstrated that this enzyme has a broad substrate specificity. XAT can esterify lutein, beta-cryptoxanthin and zeaxanthin with multiple acyl-donor substrates, yet has a preference for triacylglycerides indicating that the enzyme acts via transesterification. A series of biochemical assays further demonstrates that XAT has activity over a broad temperature and pH range. Additionally, site-directed mutagenesis was employed to demonstrate that a conserved amino acid, Ser37, is required for activity. Intriguingly, despite carotenoids being synthesised in plastids, XAT was found to accumulate in the apoplast. The implications of this compartmentalisation and a potential alternative function for XAT in wheat are investigated by analysing substrate preferences and ester formation in vitro. It is proposed that disintegration of cellular structure during wheat grain desiccation facilitates access of the enzyme to its carotenoid substrates, thereby promoting and, in turn, controlling the timing of esterification, a novel mechanism of the regulation of carotenoid metabolism.
The second chapter of this thesis begins by investigating the in vivo activity of XAT, which is confirmed via heterologous expression in carotenoid-accumulating rice callus. Results presented further establish that XAT can function when co-expressed and co-located with its substrates within the plastids of living cells as well as in species which normally accumulate exclusively un-esterified xanthophylls. The second chapter also explores the activity of XAT cereal homologs from maize, barley and rice. Expression of the maize and barley XAT homologs was found to coincide in tissues which accumulate xanthophyll esters. Further, the rice XAT homolog was observed to have xanthophyll acyl-transferase activity, producing xanthophyll esters when heterologously expressed in rice callus. Taken together, this suggests that the mechanisms of xanthophyll esterification is likely to be conserved amongst cereals.
Overall, results presented in this thesis extends our understanding of carotenoid biosynthesis beyond the production of lutein and xanthophylls to the production of xanthophyll esters. Given that the accumulation of carotenoids is governed by both the rates of synthesis and degradation, understanding the mechanisms of esterification provides new opportunities for discovery and applications for biofortification to increase the nutritional status of crops.
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Wang, Chih-Kai, i 王致凱. "Catalyst studies for lactic acid esterification". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/86525377724504873100.
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碩士東海大學
化學工程與材料工程學系
99
Esters of lactic acid are non-toxic、soluble、non-volatile and have fruit flavor. It is also biodegradable and have wide applications, particularly as regulations and consumer preferences increase the demand for “green” chemicals. They are ideal green solvents which are used as the cleaning agents for the circuit board and electronic raw material. In addition, butyl lactate and esterification of lactic acid with other alcohol are solvents for paint and plastics. Esters of lactic acid also can be used to produce natural resins、 paints、printing inks, dry lotion, adhesive and so on. The thesis uses acidic cation exchange resins and inorganic solid-acid catalysts to catalyze the esterification of lactic acid with alcohol. Among acidic cation exchange resins, Dowex 50wx8-100 had the best ester yield(butyl lactate yield was 89%).Among inorganic solid-acid catalysts, TiO2-Al2O3 had the best ester yield (butyl lactate yield was 95.7%). We used XRD、TFSEM、TGA、BET and EDS to analyze TiO2-ZrO2 and TiO2-Al2O3 catalysts prepared by co- precipitation. The correlation between esterification activity and catalyst acidic properties were investigated
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Chang, Min-Chung, i 陳明志. "Enzymatic Esterification Reactions at High Pressure". Thesis, 1997. http://ndltd.ncl.edu.tw/handle/13495379490107883252.
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邱明豐. "Characterization of Esterification/Partial Oxidation Bifunctional Catalysts". Thesis, 2001. http://ndltd.ncl.edu.tw/handle/92536795845251315872.
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碩士國立中正大學
化學工程研究所
89
Catalyzed by styrene-divinyl benzene copolymer (SDB)-supported Pd (Pd/SDB) catalysts, ethyl acetate can be formed from water-containing ethanol via concomitant partial oxidation and esterification reaction. The partial oxidation reaction is carried out over palladium clusters on the catalysts. The esterification reaction is catalyzed by protons formed from the spontaneous dissociation of acetic acid and can be enhanced by addition solid acid catalysts. After the reaction, there is no evidence of palladium oxide formation suggesting that the oxidation reaction takes place via the adsorbed oxygen. In addition, concomitantly with Pd leaching, increase of average Pd cluster size was observed. Pd-Pd coordination number increases from 3.0 to 7.9 and the Pd content decreases from 1.0 to 0.55 wt%. Addition of solid acid catalysts such as Amberlyst 15, slightly reduces leaching and growth of Pd clusters but the yield pattern of the solid-acid-promoted Pd/SDB catalyst system were still not satisfied. Therefore, zeolite supported metal catalysts with bifunctional catalytic properties were developed. In order to understand the relationship between structure and catalytic properties, EXAFS (Extended X — Ray Absorption Fine structure) spectroscopy was used to characterize the catalysts. For considering the utilization of the catalysts in commercial plant, aging tests were performed and then followed with regeneration experiments. TGA (Thermal Gravity Analysis ) and TPO ( Temperature Programmed Oxidation ) were used to investigate optimal regeneration temperature. The testing results indicated the catalysts present very good stability maintenance and the activity is only slightly loss after regeneration; after four months run the ethanol conversion still keep 58 % , and ethyl acetate selectivity also keep about 90 %.
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LIN, ZONG-YING, i 林宗穎. "Optimal Design of Mixed Acid Esterification System". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/10087402492357933435.
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碩士東海大學
化學工程與材料工程學系
104
Reduced equipment costs and increased conversions are notable features of reactive distillation processes. On the other hand, dividing-wall distillation units can not only reduce equipment costs, but also save energy. In the context, this study explores the design and optimization of a reactive distillation system involving the esterification of mixed acids with methanol. The main purpose of the process is to produce 98 wt% methyl acetate and 99 mole% methyl propionate, and to remove wastewater at the same time. A conventional reactive distillation process is designed and optimized with the goal of minimizing its total annual cost (TAC), and the effect of methanol to mixed acid ratio (Rm) is explored in the process optimization. It has been shown that when 1 ≤ Rm ≤ 1.022, only two columns are needed to achieve the specified product purities. However, when Rm is larger than 1.022, an additional column is required. It has been found an optimal conventional reactive distillation (RD) system can be obtained when Rm is set at 1.022. On the other hand, the optimal RD system can be transformed to a reactive dividing-wall column (R-DWC) scheme. It can be done with an iterative optimization procedure. The optimized R-DWC scheme revealing a 49.1% reduction in total reboiler duty can be realized, when compared with the optimal conventional RD scheme. In terms of TAC, the R-DWC scheme is also favored with a TAC that is 15.1% less than that of the RD scheme.
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chieh, chang chen, i 張朕杰. "study on the catalytic esterification of cellulose". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/81462286830530247078.
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碩士南台科技大學
化學工程與材枓工程系
98
In this study, the cotton as the raw material compound was synthesized by the esterification to cellulose acetate, and we investigated the reaction time, reaction temperature, catalyst volume, catalyst type on the degree of acetylation, degree of substitution, and molecular weight. The result was analyzed by fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (NMR) for structural identification of cellulose acetate and the chemical titration method and gel penetration chromatography (GPC) for studying the degree of substitution and molecular weight. The experimental results have found that the degree of acetylation, degree of substitution and molecular weight were various on the different reaction temperature, reaction time, catalyst volume, and reaction conditions. When changing the reaction temperature, reaction time and the closed-type reactor, the degree of acetylation and degree of substitution were increasing when the reaction time or temperature increased, and molecular weight was decreasing when the reaction temperature increased; however, if the reaction temperature, reaction time and open-type reactor, the degree of acetylation and degree of substitution were decreasing when the reaction time or temperature increased. When changing the catalyst volume, the degree of acetylation and degree of substitution were increasing when catalyst volume increased, and the degree of substitution was slightly increasing when the reaction time increased. The product have the better quality and less impurities when added the chloroform during the reaction, but the molecular weight and the degree of substitution were lower without chloroform. The cotton have various preprocessing, and the color also have different. Comparing the white color degrees of products were: preprocessing C > preprocessing B > preprocessing A. Controlling the efficiency of molecular weight contribution was changed with different solvent. In this study, comparing the control of the efficiency of molecular weight contribution were: 80 % glacial acetic acid > 25 % glacial acetic acid > acetone. For the pulp preprocessing, the preprocessing C was more whiteness after the alkali treatment. Compare with preprocessing of the cotton, the pulp contain more lignin, and it was hardly purge after the pre-treatment, so the appearance was more yellowish to the preprocessing C.
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Tadevosyan, Arevik. "Biodiesel production through ionic liquid catalysed esterification". Master's thesis, 2017. http://hdl.handle.net/10198/14667.
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Biodiesel is an alternative fuel diesel that can be produced from vegetable oils and animal fats. There is a recent growing interest in the development of alternative technologies to the oil economy, based on renewable energy sources. A possible solution is a biofuel usable in compression-ignition engines, produced from biomass rich in fats and oils. A wide range of raw materials can be used in the production of biodiesel. Nevertheless, the use of sources that do not compete with the food market like waste cooking oils, which usually feature high levels of free fatty acids (FFA’s), can put problems in the process of production of biodiesel through alkaline transesterification. These problems are partially overcome by the use of catalysts, such as ionic liquids (IL’s) that also promote reactions of esterification of FFA’s to biodiesel. Thus, the objective of this work consists in the study of the influence of IL's application in the catalysis of: esterification reactions of organic acids to the corresponding methyl esters.
In the first part of the work the influence, as catalysts, of several ionic liquids in the esterification reaction of oleic acid was analyzed. The experimental conditions were as follows: reaction time 6 hours, oleic acid / methanol molar ratio = 1/10 and temperature 90 ° C. The ionic liquids evaluated were as follows: 1-butyl-3-methylimidazolium hydrogen sulfate ([BMIM][HSO4]), 1-butyl-3-methylimidazolium methanesulfonate ([BMIM][CH3SO3]), 1-butyl-3-methylimidazolium methylsulfate ([BMIM][CH3SO4]), 1-metylimidazolium hydrogen sulfate ([MIM][HSO4]) and tributylmethylammonium methylsulfate. The values obtained for the conversion of the oleic acid esterification reaction showed that the ionic liquid [BMIM] [HSO4] would be one of the most promising catalysts.
In a second part of the work, the recovery of LI [BMIM] [HSO4] was studied and several esterification reactions of oleic acid were carried out using a quantity of catalyst of 10 wt%, 15 wt% and 20 wt% relative to the mass of oleic acid. The experimental conditions were as follows: reaction time 6 hours, oleic acid / methanol molar ratio = 1/10 and temperature 90 ° C. The reaction yield was found to be 76.6% to 10% IL, 83.3% to 15% IL and 84.8% to 20% IL. These yields decreased to 58.2% (10% IL) with 4 cycles of recycling, 75.2% (15% IL) with 5 cycles of recycling and 77.1% (20% IL) with 5 cycles of recycling. The results obtained confirm that it is possible to reuse this IL in successive reactions of esterification without great loss of yield and with this to significantly reduce the costs associated with the purchase of these compounds that are quite expensive.O biodiesel é um combustível alternativo que pode ser produzido a partir de óleos vegetais e de gorduras animais. Atualmente existe um crescente interesse no desenvolvimento de tecnologias alternativas à economia do petróleo baseadas em fontes de energia renováveis. Uma possível solução é a utilização de um biocombustível em motores de compressão-ignição, produzido a partir de biomassa rica em óleos e gorduras. Para a produção de biodiesel pode ser usada uma ampla gama de matérias-primas. No entanto, o uso de fontes que não competem com o mercado alimentar, como por exemplo os óleos alimentares usados, que geralmente têm um elevado nível de ácidos gordos livres (AGL´s), pode trazer problemas ao processo de produção de biodiesel através da transesterificação alcalina. Estes problemas são parcialmente ultrapassados usando catalisadores, tais como os líquidos iónicos (LI´s), que também promovem as reações de esterificação dos AGL´s a biodiesel. Assim, o objetivo desta dissertação de mestrado consistiu no estudo da aplicação de líquidos iónicos como catalisadores nas reações de esterificação de ácidos orgânicos aos correspondentes ésteres metílicos. Na primeira parte do trabalho analisou-se a influência, como catalisadores, de diversos líquidos iónicos na reação de esterificação do ácido oleico. Os líquidos iónicos avaliados foram os seguintes: 1-butyl-3-methylimidazolium hydrogen sulfate ([BMIM][HSO4]), 1-butyl-3-methylimidazolium methanesulfonate ([BMIM][CH3SO3]), 1-butyl-3-methylimidazolium methylsulfate ([BMIM][CH3SO4]), 1-metylimidazolium hydrogen sulfate ([MIM][HSO4]) and tributylmethylammonium methylsulfate. Os valores obtidos para a conversão da reação de esterificação do ácido oleico mostraram que o líquido iónico [BMIM][HSO4] seria um dos mais promissores como catalisador. Numa segunda parte do trabalho procedeu-se ao estudo da recuperação do LI [BMIM][HSO4], tendo-se realizado diversas reações de esterificação do ácido oleico usando uma quantidade de catalisador de 10%, 15% e 20% (m/m) relativamente à massa de ácido oleico. As condições experimentais foram as seguintes: tempo de reação 6 horas, razão molar ácido oleico/metanol = 1/10 e temperatura 90 °C. Verificou-se que o rendimento da reação foi de 76,6 % para 10% de LI, 83,3% para 15% de LI e 84,8% para 20% de LI. Estes rendimentos diminuíram para 58,2% (10% de LI) com 4 atapas de reciclagem, 75,2% (15% de LI) com 5 etapas de reciclagem e 77,1% (20% de LI) com 5 etapas de reciclagem. Os resultados obtidos permitem confirmar que é possível reutilizar este LI em reações sucessivas de esterificação sem grande perda de rendimento e com isso diminuir significativamente os custos associados à compra destes compostos que são bastante caros.
Կենսադիզելն այլընտրանքային դիզելային վառելիք է, որն ստացվում է բուսական յուղերից և կենդանական ճարպերից: Վերջին շրջանում աճում է հետաքրքրությունն այլընտրանքային տեխնոլոգիաների` նավթային տնտեսության, հիմականում վերականգնվող էներգիայի աղբյուրների նկատմամբ: Հնարավոր լուծում է ներքին այրման շարժիչներում կենսավառելիքի օգտագործումը, որն արտադրված է ճարպերով և յուղերով հարուստ կենսազանգվածից: Կենսադիզելի արտադրության մեջ հնարավոր է օգտագործել հումքի լայն ընտրանի: Օգտագործվող հումքի աղբյուրները չեն մասնակցում պարենային շուկայի մրցակցությանը: Այդպիսիք են` խոհանոցային թափոններ հանդիսացող յուղերը, որոնք հիմնականում բնորոշվում են խնդրահարույց ազատ ճարպային թթուների (ԱՃԹ) մեծ պարունակությամբ: Այս խնդիրը մասամբ հաղթահարվել է` օգտագործելով կատալիզատորներ, ինչպիսիք են իոնային հեղուկները (ԻՀ), որոնք նույնպես նպաստում են կենսադիզելում ԱՃԹ-ի եթերացմանը: Այսպիսով, այս աշխատանքի նպատակն է ուսումնասիրել իոնային հեղուկ կատալիզատորների ազդեցությունը համապատասխան մեթիլեթերների հետ օրգանական թթուների եթերացման ռեակցիաներում: Աշխատանքի առաջին մասում հետազոտվել է մի քանի իոնային հեղուկների ազդեցությունն օլեինաթթվի եթերացման ռեակցիայում: Փորձի պայմանները հետևյալն են. ռեակցիայի ժամանակը ` 6 ժամ, օլեինաթթու / մեթանոլ մոլային հարաբերակցությունը` 1/10, ջերմաստիճանը 90°C: Հետազոտվող իոնային հեղուկները հետևյալն են. 1-բութիլ-3-մեթիլիմիդազոլիումի հիդրոսուլֆատ ([BMIM][HSO4]), 1-բութիլ-3-մեթիլիմիդազոլիումի մեթանսուլֆոնատ ([BMIM][CH3SO3]), 1-բութիլ-3-մեթիլիմիդազոլիումի մեթիլսուլֆատ ([BMIM][CH3SO4]), 1-մեթիլիմիդազոլիումի հիդրոսուլֆատ ([MIM][HSO4]) և տրիբութիլմեթիլամոնիումի մեթիլսուլֆատ: Օլեինաթթվի եթերացման ռեակցիայի արդյունքները ցույց տվեցին, որ [BMIM][HSO4] իոնային հեղուկն ամենախոստումալից կատալիզատրներից մեկն է: Աշխատանքի երկրորդ մասում ուսումնասիրվել են [BMIM][HSO4] իոնային հեղուկի վերականգնումը և օլեինաթթվի եթերացման մի քանի ռեակցիաներ, որոնցում օգտագործված կատալիզատորի զանգվածը եղել է օլեինաթթվի զանգվածի 10%, 15%, 20%-ը: Փորձի պայմանները հետևյալն են. ռեակցիայի ժամանակը ` 6 ժամ, օլեինաթթու / մեթանոլ մոլային հարաբերակցությունը` 1/10, ջերմաստիճանը 90°C: Ռեակցիայի ելքը կազմել է 76.6% ԻՀ-ի 10%-ի դեպքում, 83.3% ` ԻՀ-ի 15%-ի դեպքում և 84.8%` ԻՀ-ի 20%-ի դեպքում: Այս ելքերը նվազել են մինչև 58.2% (10% ԻՀ)` վերամշակման 4 ցիկլից հետո, 75.2% (15% ԻՀ)` վերամշակման 5 ցիկլից հետո, 77.1% (20% ԻՀ)` վերամշակման 5 ցիկլից հետո: Ստացված արդյունքները հաստատում են, որ հնարավոր է այս ԻՀ-ի վերաօգտագործումը եթերացման հաջորդական ռեակցիաներում` առանց ելքի մեծ կորստի, և զգալիորեն նվազեցնել այդ, բավականին թանկ, միացությունների գնման հետ
38
Tsai, Ruei-Chiang, i 蔡瑞強. "Side-Reactor Configuration for Acetic Acid Esterification". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/23981994876849362955.
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碩士臺灣大學
化學工程學研究所
95
Reactive distillation (RD) combines reaction and separation in a single unit to reduce energy consumption and capital investment. Despite of potential advantages, the reactive distillation may suffer from maintenance/design problems such as catalyst deactivation/replacement and hardware design (for catalyst packing), especially for heterogeneous catalyst such as ion exchange resin. In this work, an alternative design, side reactor configuration, is sought and the processes of interest are the production of the ethyl acetate (EtAc) and the butyl acetate (BuAc) via esterification. The reactive distillation study in (Tang, et al., 2005) reveals that almost 90% conversion takes place in the column base of the RD and the rest of the 10% conversion occurs in the 10 reactive trays. This naturally leads to a coupled reactor/distillation configuration where all of the catalyst is packed in the bottoms base, denoted as Single Reactive Tray reactive distillation (SRT) hereafter. This mitigates the maintenance problem associated with conventional RD. However, simulation results show that, with the same amount catalyst loading (Wcat,RD), the SRT configuration cannot achieve the same performance as the RD (~93% conversion). Another alternative is adding external reactors to the Single Reactive Tray distillation column and this is termed as the Side Reactor Configuration (SRC). Unlike conventional reactive distillation design, the SRC design is less clear and design variables include: catalyst loading in the column base (Wcat,bot), % of equilibrium conversion for side reactor (% Xeq), sidestream withdrawn and return trays (Nss,r), sidestream flow rate (Fss). A systematic design procedure is devised for the SRC design and the objective function to be minimized is the total annual cost (TAC). The results show that the TAC of the SRC only increases by a factor of 5% as compared to that of the RD. The butyl acetate (BuAc) system is considered next. It differs from the EtAc system in (1) relatively even reaction distribution across reactive zone and (2) boiling point distribution where both reactants are intermediate keys. Two possible SRC configurations are explored. One is the pre-reactor (only one inlet stream to the column) plus side reactors and the other is complete side reactor scheme where all reactors coupled with the column. The results show that the complete side reactor scheme performs much better as compared to the pre-reactor plus side reactor scheme. As the total number of reactor increases to four, the TAC only increases by a factor of 25% as compared to that of the RD. For the two cases studied, the TACs of the SRC is slightly larger than that of the RD, however, considering the ease of catalyst replacement, the Side Reactor Configuration offers attractive alternative to conventional reactive distillation.
39
Yang, Yung-Ching, i 楊永慶. "Synthesis of Monostearin via Lipase-catalyzed Esterification". Thesis, 2002. http://ndltd.ncl.edu.tw/handle/47186518242228902478.
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碩士國立臺灣科技大學
化學工程系
90
Monoglyceride (MG) is one type of derivative of acylglycerol, in which one of the hydroxyl group of glycerol is esterified with fatty acid. MGs are most widely used as additives and emulsifiers in the food, cosmetic and pharmaceutical products. The conventional chemical methods to produce MG in industry are usually carried out at higher temperatures (220-250℃) under nitrogen atmosphere by employing inorganic alkaline catalysts. The major disadvantages of these processes are: it needs high energy, it produces several undesirable by products and also the quality of product is very low which needs further purification steps. Furthermore, these chemical methods produce serious environmental objections. Therefore, an efficient, economical and environmentally friendly process is utmost important to synthesis MG. In the present investigation, it was planned to explore an efficient method for the synthesis of monoglyceride (MG) from glycerol and fatty acid (stearic acid) by the use of lipases. During this investigation various factors such as nature of lipase, amount of lipase, molar ratio of substrates, nature of solvent, volume of solvent, temperature, effects of water content, different kinds of FFA and reuse of lipase in the synthesis of MG were studied. Under the following reaction conditions: the lipase is Novozym 435, the molar between stearic acid and glycerol is 1:4, the amount of lipase is 266.5 U, the solvent is acetone, the volume of acetone is 4 mL, the reaction temperature is 50℃, the stirring speed is 500 rpm, and add molecular sieves. After 8 hr of reaction time, the content of monostearin in the acylglycerides is about 95.6±1.6 wt% with 84.3±0.6 % of degree of esterification was achieved. Further studies were carried out to enhance the degree of esterification up to 91.48±1.2 %. Moreover, during this investigation purifications of MG by low temperature solvent crystallization and alkali neutralization were carried out. The content and overall yield of monostearin after low temperature solvent crystallization is 95.3±0.69 wt% and 44.1±2.3 %, respectively. The content and overall yields of monostearin after neutralization are 99.41±1.1 wt% and 53.68±3.83%, respectively.
40
Lin, Hsin-Mei, i 林欣玫. "Biodiesel Synthesis by Esterification/ Transesterification Using Solid Catalysts". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/74667175189579132886.
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碩士國立臺灣大學
化學工程學研究所
100
Biodiesel is an alternative fuel for traditional fossil fuel. It can be produced by transesterification from triglyceride. In this study, we use solid catalysts to catalyze esterification and transesterification in order to solve the problems of free fatty acid (FFA) in the feedstock oil. The first method：Both esterification and transesterification were catalyzed simultaneously by solid acid catalyst. In experiment, we used commercial lard as feedstock oil, and SZA (Sulfated Zirconia Alumina) solid acid catalyst to catalyze both reactions. We studied different reaction parameters, the catalyst amount, the methanol/oil molar ratio, and reaction temperature. We also chose waste cooking oils (WCO) which contained FFA as feedstock oil. Under methanol/oil molar ratio 12/1, catalyst amount 1wt%, reaction temperature 150oC, and reaction time 2hr, the biodiesel yield reached 80%. Moreover, the biodiesel yield of WCO showed that different feedstock oils did not influence the efficiency of catalyst. So we could use the low quality WCO as the feedstock oil to decrease cost of oil. The second method：The second method was two sequence reactions. Under mild reaction temperature 60oC, use SZA solid acid catalyst to catalyze esterification first. The objective was to convert FFA into ester. Then used calcium diglyceroxide Ca(C3H7O3)2 solid base catalyst to catalyze transesterification. We added 5wt% and 20wt% palmitic acid into soybean oil to simulate the feedstock oil which contained FFA. The research result showed that it was necessary to esterify FFA in oil in the first step, and the overall yield was 80% after this two sequence reactions.
41
Chou, Fang Ru, i 周芳如. "Nanolization of Layered Compounds as Catalysts in Esterification". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/09832193945882777036.
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碩士國立暨南國際大學
應用化學系
103
The present study is an attempt to generate a new way for the synthesis of two dimensional nanosheets which has a higher specific surface area and better catalytic properties. The synthesis was carried out in two steps, intercalation of the layered materials with organic entities followed by exfoliation in various nonpolar solvents. The layered oxide materials HNbWO6 • 1.5H2O and HTaWO6 • 1.5H2O were utilized as the precursors for the synthesis of nanosheets. The organic compounds- ortho-phenylenediamine, hexadecylamine and melamine were intercalated into the host materials at room temperature. Further ultra-sonication was carried out in nonpolar solvents- toluene, dichloromethane and tetrahydrofuran correspondingly. The obtained solid acid nanosheets were applied in the acetic acid esterification reaction as catalyst and the performance was further evaluated through gas chromatography.
42
Tsai, Hsin-Chuan, i 蔡幸娟. "Reaction Condition Study on Trans-esterification of Soybean". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/05686255900138339451.
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碩士國立臺中教育大學
科學應用與推廣學系科學教育碩士班
100
Biodiesel is composed from raw vegetable oil or animal fat. As a biofuel either pure or mixed with fossil fuels, it is a potential clean form of energy. It is biodegradable, non-toxic, and generates less pollution after combustion than fossil fuels. Solid basic catalysts CaO, Ca(OH)2, and Ca(NO3)2 are used for the transesterification of soybean oil and methanol. A three-factor, three-level orthogonal experiment is conducted to analyze the efficiency of transesterification among the catalyst types, calcined temperature, and catalyst quantity. Calcined catalysts catalyze the soybean oil transesterification reaction. Results show that CaO has the best transesterification performance when the oil methanol ratio is at 12, atmosphere conditions are at 60℃, and reaction time is 3 h. All calcined catalysts are analyzed to determine the differences between their physical properties by using XRD, SEM-EDS, and FT-IR. Disposed eggshells are reused and calcined into the CaO catalyst for the transesterification of soybean oil and methanol. A significant amount of soap product produced by free fatty acids and the basic catalyst inhibited the transesterification reactions. Catalyst quality influences the results of transesterification and biodiesel quality. The catalyst can be deactivated if moisture and carbon dioxide are adsorbed from the atmosphere. Results show that a transesterification rate above 95% is possible. The optimal reaction conditions when using the eggshell catalyst are achieved when the calcined catalyst is at 900℃ for 2 h, 2% wt catalyst is added, the oil methanol ratio is at two, and reaction time is 3 h. The eggshell catalyst can be reused for 10 batches. A separate study on heating energy and the transesterification rate identified that the optimal microwave heating power is 800 W with 30 min heating time. Using cement as a catalyst for the same reaction showed that a transesterification rate above 98% is possible. Optimal reaction conditions when using the cement catalyst are achieved when the calcined catalyst is at 650 ℃ for 3 h, 4% wt catalyst is added, the oil methanol ratio is at 0.5, and reaction time is 3 h at 65℃. The cement catalyst can be reused for 4 batches. A separate study on heating energy and transesterification rate identified that the optimal microwave heating power is 800 W with 30 min heating time.
43
陳光興. "Studies on the Esterification by Using Immobilizd Lipase". Thesis, 1998. http://ndltd.ncl.edu.tw/handle/40779274724348652311.
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碩士東吳大學
微生物學系
86
Four different commercial lipases of Pseudomonas spp (PS-P), Candida rugosa (CR-P), Mucor javanicus (MJ-P) and Rhizopus arrhizus (,RA-P) have been immobilized by adsorption with celite (PS-A, CR-A, MJ-A, RA-A) and by entrappment with hydrophobic silane (PS-E, CR-E, MJ-E, RA-A). The conversion rate of capronic acid and ethanol to ethyl caproate of thase free and immobilized lipase in organic solvent n-hexane, in aqueous alcohol solution, and in the supercritical fluid of carbon dioxide system have been measured and compared in this study. The free PS lipase (PS-P) is found to have the highest esterification activity in n-hexane. The conversion rate can reach 80% after reaction for 8h. Each mg o f PS-P can synthesize 0.0462 μM of ethyl caproate per minute. The esterification activity of lipase is increased greatly after immobilization, especially for the entrapped PS lipase (PS-E). The conversion rate of PS-E can reach 90% at 1.5h, and each gram of PS-E can synthesize 298.3 μM of ethyl caproate per min. The optimum enzyme dose for adsorbed lipase is 400mg/g of celite, but for entrappment in hydrophobic silane is more than 800mg. Adding trace amount of water in n-hexane can increase the esterification activity of celite adsorbed lipase up to water content to 0.0625%. Among these four lipase, only PS lipase show some esterification activity in 40% alcohol solution. The conversion rate of caproic acid to ethyl caproate for PS-P, PS-A and PS-E are 15.4%, 23% and 40% respectively. The ethyl caproate synthesized by PS-E is more stable than PS-P and PS-A, and it''s rate of ester formation is increased with the increasing in alcohol content. In 60% alcohol solution, the conversion rate for PS-E at 5h is 43%. The immobilized lipases have been used repeatly batchwise for ethyl caproate synthesis in n-hexane or in 40% alcohol solution. For celite adsorbed lipase (PS-A), more than half enzyme activity is lost at the second batch no matter how is the polarity of the reaction medium. But for the hydrophobic silane entrapped PS lipase (PS-E), the half life of enzyme activity in n-hexane is 40 batches and in 40% alcohol solution is 16 batches. The immobilized lipases have also been applied in the supercritical fluid of carbon dioxide system for ethyl caproate synthesis. Better results can be obtained for the entrapped PS lipase (PS-E, the conversion rate can be got to 80% after starting for 8h and maintained at 50% when reaction proceed for 50h.
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Chen, Tzu-Ming, i 陳子明. "Pervaporation assisted pre-esterification in a biodiesel process". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/4fzb6f.
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碩士國立臺灣大學
化學工程學研究所
105
Nowadays, our life is intimately linked with fossil fuels. With more and more concerns about oil shortage and environmental issues, seeking for alternative energy turns out to be crucial. Biodiesel is a kind of general biofuel, and it is clean, renewable and has combustion properties like petroleum-based diesel. In order to overcome the saponification and hydrolysis problems of producing biodiesel by using alkaline catalysts which is usually caused by free fatty acid (FFA) contained in raw oil. A two-step method, pre-esterification followed by transesterification, is proposed. In our study, we focused on the first step: pre-esterification. In most literatures, small acid molecular compounds were used to perform the pre-esterification reactions, which is different from the main FFA component in the raw oil. We designed a reactor consisting of a pervaporation module. The esterifications of n-propanol and caproic acid were performed with/without pervaporation for comparison. By means of continuously removing the water from the solution via prevaporation, the overall reaction favors the product side, thus further to enhance the conversion of caproic acid based on Le Chatelier principle. The results showed the hydrophilic property of Crosslinking PI membrane. We also investigated various parameters including initial molar ratio of n-propanol to caproic acid (M), reaction temperature, ratio of effective membrane area to the reaction solution volume (S/V) to search the optimal condition. Compared with no pervaporation, the results showed that the conversion was enhanced 3 % at 70℃, using 5 wt % Amberlyst 15 catalyst and M= 1.39 by pervaporation in 12 hours. Instead of Amberlyst 15, the conversion was enhanced 6 % when 0.05 wt % sulfuric acid catalyst was used with pervaporation in 9 hours.
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Lin, Li-Jie, i 林立杰. "Kinetic Behavior Study on the Heterogeneous Esterification of". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/ggd5js.
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碩士國立臺灣科技大學
化學工程系
106
The heterogeneous kinetics behavior was investigated with a batch reactor for the synthesis of linolenic acid n-butyl ester from linolenic acid and n-butanol over the cation-exchange resins, Amberlyat 39. The experiments were conducted at tempertures from 343.15 K to 363.15 K. Additionally, the effects of molar ratio of alcohol to acid in the feed stream, the mass transfer resistances on the catalytic reaction, and the different levels of catalyst loadings were also observed. Both reaction rate and equilibrium conversion of acid increased with increase of reaction temperature, while increasing molar ratio of alcohol to acid in the feed stream and catalyst loading increase the reaction rate. It was also found that the reaction rate is not apparently different when operating at different agitation rates and different particle sizes of catalyst. Therefore, these results show that the mass transfer resistances are neglegible over the entire operating conditions. The kinetic data of the synthesis of linolenic acid n-butyl ester were correlated with the ideal-quasi-homogeneous (IQH), the non-ideal-quasi-homogeneous (NIQH), the Eley-Rideal (ER), and the Langmuir-Hinshelwood-Hougen-Watson (LHHW) models, respectively. The NRTL model was used to calculate the activity coefficients for each reacting species. The optimal values of the kinetic parameters were determined from the data fitting. The LHHW model yielded the best representation for the kinetic behavior of heterogeneous catalytic synthesis of linolenic acid n-butyl ester.
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Liu, Wen-Tzong, i 劉文宗. "Esterification synthesis of n-butyl propionate by reactive distillation". Thesis, 2002. http://ndltd.ncl.edu.tw/handle/29448513497004518347.
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博士國立清華大學
化學工程學系
90
The objective of this study was to investigate the reactive distillation technique, a promising technology combining distillation and reaction in one column in order to reduce capital and operating cost, using the esterification of n-butyl propionate from propionic acid and n-butanol as the model system. The research contents included investigation of chemical equilibrium between each pair in product mixtures and screening of catalysts among the commercial solid acids like acidic exchange resins. A 50 mm column was used to carry out the catalytic distillation experiments and three kinds of catalysts installation methods were tested. The computer simulation was performed to investigate how the operating variables such as reflux ratio, stripping area, reaction area, rectification area, and boil-up ratio affect the purity of the product and the conversion of propionic acid. The obtained results of this study are listed as follows: 1.The VLE data of propionic acid + n-butyl propionate were established from the VLE experiments conducted at pressures ranged from 60 kPa~101.3kPa. The NRTL model was found to be the most appropriate to represent liquid phase non-idealities. The Hayden-O’Cornell equation was used to account for vapor phase association. The UNIFAC was found not to describe the VLE because it predicted an azeotrope that was not observed in the experiments. The NRTL-HOC model predicted the existence of a double azeotrope at low pressures that has been reported in the literature. 2.The Amberlyst 35 was observed to possess the highest activity and physical strength among the acidic exchange resins used in the catalyst screening. From the study on chemical reaction kinetics, it was found that the reaction was endothermic with a heat of reaction of 0.46 kcal/mol. Heat due to dissociation of propionic acid was postulated to contribute to the total heat of reaction. The mechanism for this reaction was believed to follow the Eley-Rideal model in which the adsorbed propionic acid reacted with n-butanol in the bulk liquid. The controlling step was the adsorption of propionic acid. 3.N-Propionate with a high purity could be produced from the bottom of a reactive distillation column. The co-jet tray method for the installation of solid catalysts was recommended because of high liquid holdup, low cost, and easy replacement of catalysts. 4.The key to produce n-butyl propionate with a purity of >99.5 wt% was to maintain the bottom temperature of a reactive distillation column sufficiently close to the boiling point of n-butyl propionate. The key to assure a complete conversion of propionic acid in order to prevent from a high separation cost of propionic acid was the setup of a reaction zone, including catalysts amount, liquid holdup, etc. The presence of redundant n-butanol did not result in a higher conversion of propionic acid because it lowered temperature in the reaction zone. The simulation based on the equilibrium stage model using the Aspen plus simulator was found to correlate the experimental data on temperature profile in column and composition in the bottom and top well. The regressed kinetic parameter could represent both mass transfer and chemical kinetic effects.
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Chang, Wei-Lin, i 張濰麟. "Preparation of Hydrophobic Catalysts and Application of Esterification Reaction". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/z24422.
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碩士國立中正大學
化學工程研究所
103
The objective of this study is to prepare hydrophobic catalyst. The selection of granule type catalyst support is Pd/zeolite(CBV760-Pd). We deposited nickel nitrate solution as a nickel catalyst precursor on the catalyst supports by incipient wetness impregnation, nickel catalyst content of Pd/zeolite was 2.5 wt.%, and calcined the sample that had been removed the solvent by vacuum drying method under atmosphere at 450 ℃for 30 minutes in the box furnace. Then, grow CNT layer by CVD process after the catalyst precursor was calcined, which hydrogen acted as reduction agent, acetylene as carbon source and argon as ambient gas for heating and cooling stage. The reaction temperature was 500 ℃. At different reaction time(15~130 min), we obtained the Pd/CNT/zeolite which is a hydrophobic catalyst support of core-shell structure(different core-shell ratio). At the beginning, we used 0.5 g catalyst supports to do CVD growth. Observed from the SEM, the surface of Pd/CNT/zeolite was covered by CNTs. The CNT diameter increases as the reaction time goes on. After doing the hydrophobic measurement, the contact angle of Pd/CNT/zeolite is bigger than 150˚ when the reaction time is more than 50 minutes. The surface of Pd/CNT/zeolite is super hydrophobicity. After that, the weight of catalyst supports was increased from 0.5 g to 2.5 g. The contact angle of Pd/CNT/zeolite is also bigger than 140˚ when the reaction time is more than 50 minute. CNT layer can let EtOH, HOAc, EtOAc diffused into the catalyst by affinity test. The affinity between Pd/zeolite and solution: H2O ≈ EtOAc > HOAc > EtOH. The affinity between Pd/CNT/zeolite and solution: EtOAc > HOAc > EtOH >> H2O. The batch reactor used to esterification reaction. The feed is 75% EtOH. The equilibrium conversion is 52~53%. For conversion, the increased rate of Pd/zeolite is higher than Pd/CNT/zeolite. The continuous fixed-bed reactor used to esterification reaction. At 1 and 10 atm, the conversion of Pd/zeolite is higher than Pd/CNT/zeolite. At 20 atm, the equilibrium conversion of Pd/zeolite and Pd/CNT/zeolite is 59~62%. At 10 and 20 atm, the yield of Pd/zeolite close to Pd/CNT/zeolite. The outer layer of Pd/CNT/zeolite as a protection catalyst role. It can prevent Pd loss. Increased catalyst reaction time.
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邱如吟. "Kinetics of heterogeneous esterification for production of butyl propionate". Thesis, 2000. http://ndltd.ncl.edu.tw/handle/76023520659933253906.
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Alimova, Irana. "Production of biodiesel through esterification catalyzed by Ionic liquids". Master's thesis, 2016. http://hdl.handle.net/10198/13173.
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Biodiesel is an alternative diesel fuel that is produced from vegetable oils and animal fats. Currently, most biodiesel is made from oils, methanol, and an alkaline catalyst. Conventional catalysts is commonly used for catalyzing esterification of fatty acid to produce biodiesel. However, a better and greener method was found. An ionic liquid (IL) is a molten salt consisting of a cation and an anion, with low melting temperature. It offers a better solution than sulfuric acid, because it can be recycled and reused in subsequent runs after recovery steps. In this study, a Brønsted acidic IL, 1-butyl-3-methylimidazolium hydrogen sulfate ([BMIM][HSO4]) was used as a catalyst in the esterification of oleic acid with methanol into biodiesel.
The effect of different operation parameters such as methanol to oil molar ratio, amount of catalyst, reaction temperature, and reaction time were tested. The optimum conditions for esterification of oleic acid were identified as oleic acid/methanol molar ratio of 1/10, amount of catalyst 10 wt%, reaction time of 4 h, and reaction temperature of 90oC. FAME content of produced biodiesel was analyzed and confirmed using GC chromatography.O Biodiesel é uma alternativa interessante aos combustíveis fósseis, sendo produzido a partir de óleos vegetais e/ou gorduras animais. Atualmente, a maior parte do biodiesel é produzido utilizando óleos, metanol e um catalisador alcalino. Os catalisadores tradicionais são normalmente usados em catálise ácida de ácidos gordos para produzir biodiesel. Contudo, um método alternativo e mais “amigo” do ambiente tem sido recentemente, bastante estudado. Os líquidos iónicos são sais fundidos/líquidos constituídos por um catião e por um anião com pontos de fusão reduzidos. Estes compostos são uma solução melhor quando comparados com o ácido sulfúrico, podendo ser reciclados e reutilizados. Neste trabalho utilizam-se como catalisadores, ácido sulfúrico, e um líquido iónico: o 1-butyl-3-methylimidazolium hydrogen sulfate ([BMIM][HSO4]). Sendo ambos utilizados como catalisadores na esterificação do ácido oleico com metanol para produzir biodiesel. O principal objetivo deste trabalho consistiu em estudar a influência de alguns parâmetros de operação na produção de biodiesel, como seja a razão molar metanol/ácido oleico, a quantidade de catalisador, a temperatura da reação e o tempo de reação. O estudo realizado permitiu identificar as condições ótimas para cada um destes parâmetros: razão molar ácido oleico/metanol de 1/10, quantidade de catalisador de 10% em massa, tempo de reação de 4 h e temperatura de reação de 90oC. O conteúdo em ésteres metílicos de ácidos gordos (FAMEs) do biodiesel produzido foi igualmente caracterizado por cromatografia gasosa quer qualitativamente quer quantitativamente.
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Roman, Fernanda. "Biodiesel production through esterification applying ionic liquids as catalysts". Master's thesis, 2018. http://hdl.handle.net/10198/17892.
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Dupla diplomação com a Universidade Tecnológica Federal do ParanáBiodiesel is a liquid fuel obtained from several renewable sources by transesterification reaction of triglycerides. Its development is related to a new tendency: the search for alternatives to petroleum-based energy sources. Its utilization is associated with several environmental benefits, such as a reduction in pollutants emissions. However, due to the high cost associated to its usual feedstock, such as edible vegetable oils, biodiesel is not economically viable. Therefore, there’s a requisite to decrease the final price of this fuel. The logical way is by introducing cheaper feedstock into the industrial production, such as non-edible feedstock or waste cooking oil. The main characteristic of cheaper feedstock is the high content of free fatty acids (FFAs) and/or water when compared to edible feedstock. FFAs present on the feedstock must be converted into biodiesel, also referred to as fatty acid methyl esters (FAMEs), by an esterification reaction. The esterification reaction cannot be catalyzed by alkali catalyst, usually applied in the transesterification such as NaOH or KOH. Alkali catalysts in the presence of FFAs lead to the formation of soap, consuming the catalyst, decreasing its catalytic activity and turning the separation of the final products much more complex. Hence, only acidic catalysts are able to promote the esterification reaction of FFAs. Those acidic catalysts are able to catalyze both reactions, however, the rate of the transesterification reaction is about 4000 times slower than for the reactions promoted by alkali catalysts [1,2], leading to long reaction times and, again, high costs. In this way, there is an increasing need to find alternative catalysts that promote both the transesterification and the esterification reaction under adequate conditions. Thus, ionic liquids emerge as an alternative to conventional catalysts. Ionic liquids are molten salts composed of an organic or inorganic anion and an organic cation. The present study evaluated the use of the catalyst 1-methylimidazolium hydrogen sulfate ([HMIM][HSO4]) in the production of biodiesel through the esterification reaction of oleic acid. The influence of the main parameters (time, temperature, molar ratio methanol/oleic acid and catalyst dosage) on two responses (conversion of oleic acid and FAME content of the biodiesel samples) were studied through a response surface methodology (RSM) known as Box-Behnken Design (BBD). It was concluded that the most relevant parameters for both responses were the molar ratio between the reactants and the catalyst dosage. The optimum conditions for the conversion were determined as being 8 h, 110 °C, 15:1 molar ratio methanol/oleic acid and a catalyst dosage of 15 wt%, resulting in a 95% conversion and for the FAME content were 8 h, 110 °C, 14:1 molar ratio and a catalysts dosage of 13.5 wt%, leading to a content of 90%. The kinetics of the reaction were also studied. The activation energy was estimated as 6.8 kJ/mol and the pre-exponential factor as 0.0765 L2.mol-2.min-1.
O biodiesel é um combustível líquido obtido a partir de fontes renováveis através da reação de transesterificação de triglicerídeos. O interesse por este combustível está relacionado com uma nova tendência: a procura de alternativas às fontes de energia baseadas em petróleo. A sua utilização está associada a vários benefícios ambientais, como a redução da emissão de poluentes. No entanto, devido ao elevado custo associado à sua matéria-prima usual, como os óleos vegetais comestíveis, o biodiesel não é no momento atual economicamente viável. Portanto, há uma necessidade de reduzir o preço final deste combustível. Uma das formas de reduzir os custos será a de se utilizarem matérias-primas mais baratas no processo de produção, como óleos usados ou não comestíveis. A principal característica dessas matérias-primas mais baratas é a baixa qualidade quando comparada com os óleos comestíveis. Esta baixa qualidade está normalmente associada a um alto teor em ácidos gordos livres (AGL) e/ou água. Os AGLs presentes na matéria-prima devem ser convertidos em biodiesel, também conhecido por ésteres metílicos de ácidos gordos (Fatty Acid Methyl Esters: FAME), por uma reação de esterificação. A reação de esterificação não pode ser promovida por catalisadores alcalinos, geralmente aplicados na transesterificação, como o NaOH ou o KOH. Os catalisadores alcalinos na presença de AGLs levam à formação de sabão, consumindo o catalisador, diminuindo a sua atividade catalítica e tornando a separação dos produtos finais mais complexa. Apenas os catalisadores ácidos são capazes de promover a reação de esterificação de AGLs. Os catalisadores ácidos são capazes de catalisar ambas as reações, no entanto, a velocidade da reação de transesterificação é cerca de 4000 vezes mais lenta do que quando se utilizam catalisadores alcalinos [1,2], levando a longos tempos de reação e, consequentemente, custos elevados de produção. Desta forma, existe uma crescente necessidade de encontrar catalisadores alternativos que promovam tanto a reação de transesterificação quanto a reação de esterificação em condições mais favoráveis. Atualmente, os líquidos iónicos têm sido utilizados como uma alternativa aos catalisadores convencionais. Os líquidos iónicos são sais fundidos compostos por um catião orgânico e um anião orgânico ou inorgânico. No presente estudo avalia-se a utilização do catalisador hidrogenossulfato de 1-metilimidazólio ([HMIM][HSO4]) na produção de biodiesel através da reação de esterificação do ácido oleico. A influência dos principais parâmetros (tempo, temperatura, razão molar metanol/ácido oleico e quantidade de catalisador) foi estudada através de uma metodologia de superfície de resposta conhecida por Box-Behnken Design (BBD), avaliando duas repostas: a conversão de ácido oleico e o conteúdo de FAMEs. Concluiu-se que os parâmetros mais relevantes para ambas as respostas foram a razão molar entre os reagentes e a quantidade de catalisador. As condições ótimas para a conversão foram determinadas como sendo 8 h, 110°C, 15:1 relação molar metanol/ácido oleico e uma quantidade de catalisador de 15% em massa, resultando numa conversão de 95% e para o conteúdo de FAMEs foram 8 h, 110 °C, uma razão molar de 14:1 e uma dosagem de catalisador de 13,5% em peso, conduzindo a um conteúdo de ésteres metílicos de ácidos gordos de 90%. Foram também determinados os parâmetros cinéticos da reação. A energia de ativação foi estimada em 6.8 kJ/mol e o fator pré-exponencial em 0.0765 L2.mol-2.min-1.