Dissertations / Theses on the topic 'Esterification'
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Sindelar, Pavel J. "Hepatic lipase and dolichol esterification /." Stockholm, 1997. http://diss.kib.ki.se/1997/91-628-2772-3.
Full textAl-Seeni, Madeha N. "Control of hepatic cholesterol esterification." Thesis, University of Nottingham, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293154.
Full textHatcher, 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.
Full textLindmark-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.
Full textThis 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.
Bankole, Kehinde Seun. "Uncatalyzed esterification of biomass-derived carboxylic acids." Diss., University of Iowa, 2011. https://ir.uiowa.edu/etd/922.
Full textMAININI, FRANCESCA. "ESTERIFICATION OF NATURAL COMPOUNDS WITH FATTY ACIDS." Doctoral thesis, Università degli Studi di Milano, 2012. http://hdl.handle.net/2434/170495.
Full textLee, 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/.
Full textMatsumura, Hiroyuki. "Efficient Utilization of Biomass through Esterification of Cellulosics." Kyoto University, 2003. http://hdl.handle.net/2433/148642.
Full text0048
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
Dastjerdi, Zahra. "The Esterification of Naphthenic Acids for Methyl Ester Production." Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/28802.
Full textLevesque-Tremblay, Gabriel. "Pectin methyl esterification functions in seed development and germination." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/46351.
Full textLindmark, 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.
Full textNguyen, Van Chuc. "Catalytic production and esterification of aqueous solution of lactic acid." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1136.
Full textThis 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
Sergeant, Claire. "Esterification d'acides gras tissulaires par l'éthanol : influence des lipides alimentaires." Bordeaux 1, 1991. http://www.theses.fr/1991BOR10588.
Full textPhalak, 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.
Full textThompson, 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.
Full textPorter, Altic Lucas Eli. "Characterization of the Esterification Reaction in High Free Fatty Acid Oils." Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3582.
Full textMazza, 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.
Full textPabai, 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.
Full textSafari, 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.
Full textWilson, 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.
Full textTeo, 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.
Full textSattenapally, Narsimha. "SYNTHESIS AND DEVELOPMENT OF SILICON ANALOG OF FLUORESCEIN FLUOROPHORES AND ESTERIFICATION CATALYSTS." OpenSIUC, 2012. https://opensiuc.lib.siu.edu/dissertations/588.
Full textTibbits, 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.
Full textCamp, David. "Some Aspects of the Mitsunobu Reaction." Thesis, Griffith University, 1990. http://hdl.handle.net/10072/366203.
Full textThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Division of Science and Technology
Science, Environment, Engineering and Technology
Full Text
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.
Full textGumaste, 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.
Full text富洵 and 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.
Full textVenzon, 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.
Full textChiu, Li-Chun, and 邱麗君. "Protease catalyzed esterification." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/73099123030276174106.
Full text葉遠平. "Development of Esterification Catalyst." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/00798097574843762539.
Full text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.
Watkins, Jacinta. "Understanding carotenoid esterification in cereals." Phd thesis, 2019. http://hdl.handle.net/1885/186942.
Full textWang, Chih-Kai, and 王致凱. "Catalyst studies for lactic acid esterification." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/86525377724504873100.
Full text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
Chang, Min-Chung, and 陳明志. "Enzymatic Esterification Reactions at High Pressure." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/13495379490107883252.
Full text邱明豐. "Characterization of Esterification/Partial Oxidation Bifunctional Catalysts." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/92536795845251315872.
Full text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 %.
LIN, ZONG-YING, and 林宗穎. "Optimal Design of Mixed Acid Esterification System." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/10087402492357933435.
Full text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.
chieh, chang chen, and 張朕杰. "study on the catalytic esterification of cellulose." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/81462286830530247078.
Full text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.
Tadevosyan, Arevik. "Biodiesel production through ionic liquid catalysed esterification." Master's thesis, 2017. http://hdl.handle.net/10198/14667.
Full textO 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
Tsai, Ruei-Chiang, and 蔡瑞強. "Side-Reactor Configuration for Acetic Acid Esterification." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/23981994876849362955.
Full text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.
Yang, Yung-Ching, and 楊永慶. "Synthesis of Monostearin via Lipase-catalyzed Esterification." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/47186518242228902478.
Full text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.
Lin, Hsin-Mei, and 林欣玫. "Biodiesel Synthesis by Esterification/ Transesterification Using Solid Catalysts." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/74667175189579132886.
Full text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.
Chou, Fang Ru, and 周芳如. "Nanolization of Layered Compounds as Catalysts in Esterification." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/09832193945882777036.
Full text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.
Tsai, Hsin-Chuan, and 蔡幸娟. "Reaction Condition Study on Trans-esterification of Soybean." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/05686255900138339451.
Full text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.
陳光興. "Studies on the Esterification by Using Immobilizd Lipase." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/40779274724348652311.
Full text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.
Chen, Tzu-Ming, and 陳子明. "Pervaporation assisted pre-esterification in a biodiesel process." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/4fzb6f.
Full text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.
Lin, Li-Jie, and 林立杰. "Kinetic Behavior Study on the Heterogeneous Esterification of." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/ggd5js.
Full text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.
Liu, Wen-Tzong, and 劉文宗. "Esterification synthesis of n-butyl propionate by reactive distillation." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/29448513497004518347.
Full text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.
Chang, Wei-Lin, and 張濰麟. "Preparation of Hydrophobic Catalysts and Application of Esterification Reaction." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/z24422.
Full text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.
邱如吟. "Kinetics of heterogeneous esterification for production of butyl propionate." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/76023520659933253906.
Full textAlimova, Irana. "Production of biodiesel through esterification catalyzed by Ionic liquids." Master's thesis, 2016. http://hdl.handle.net/10198/13173.
Full textO 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.
Roman, Fernanda. "Biodiesel production through esterification applying ionic liquids as catalysts." Master's thesis, 2018. http://hdl.handle.net/10198/17892.
Full textBiodiesel 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.