Rozprawy doktorskie na temat „Transesterification”

The objective of our design was to create a chemical plant that uses cultivated algae grown on site in order to produce a biofuel as an alternative energy source. Currently there is a push for sustainable energy sources and biologically produced fuels are attractive due to their near net-zero carbon emissions. Algae provides a valuable source of energy due to its growth rate and sustainability. Chemical engineering principles were utilized in design; a supercritical carbon dioxide extractor for the triglycerides in the algae cells, base catalyzed transesterification reaction in continuously stirred reactors in series and separation processes at the end in order to produce a high grade biofuel for consumer applications. Emphasis on environmental consideration also went into the design, such as the use of carbon dioxide for both the growth of the algae and solid extraction process and methanol used for the transesterification and liquid extraction, allowing for easy recycle and further reducing the environmental footprint the product fuel will have.

Alternative diesel fuels have been the subject of extensive investigation. Fatty acid methyl ester (FAME) based Biodiesel manufactured from vegetable oils or animal fats is an excellent candidate to replace common diesel fuel being renewable, non-toxic and often giving rise to reduced exhaust gas emissions. The transesterification process has been commonly and widely used to produce biodiesel from vegetable oil or animal fat. Vegetable oils or animal fats generally have viscosities higher than standard diesel oil. This means that it is necessary to reduce the viscosity by means of reacting vegetable oil with alcohol in the presence of a suitable catalyst. The target product for this reaction is methyl ester, with glycerol and potentially soap produced as by products with the process of transesterification. Methylester (Biodiesel) is produced by converting triglycerides to alkylesters. A batch transesterification process has two significant mechanisms, and exhibits a mass transfer controlled region that precedes a second order kinetically controlled region. In order to control the conversion process it is useful to employ process monitoring. In particular monitoring of the mass transfer processes that limits the initial reaction rates could prove to be beneficial in allowing for process optimization and control. This thesis proposes the use of a new method of biodiesel process monitoring using low frequency (15kHz) impedance sensing which is able to provide information regarding the progress of mass transfer and chemical reaction during biodiesel production. An interdigitated (ID) sensor has been used to monitoring the biodiesel process The ID sensor is of simple construction and consists of two sets of interleaved electrodes (fingers). The two sets of electrodes are separated by a gap and when an AC excitation voltage is applied across the interleaved electrodes an oscillating electric field is developed. The response of the fluid surrounding the sensor to the applied excitation was then used to determine progress of the chemical reaction by evaluating the real and complex impedance. A significant and unambiguous change in the components of impedance has been shown to occur during mixing (mass transfer) and transesterification. The impedance measurements gained during transesterification were then used for the development of a system model. A systematic approach was used to select mathematical models and system identification techniques were evaluated. The system identification investigation used real process measurement data in conjunction with the Matlab system identification toolbox.

Enzymatic transformations in organic solvents have received increasing attention over the past 10 years and lipases have become by far the most popular enzymes in this area.The initial aim of the research was to assess the effect of small modifications to the acyl donor in the transesterification reactions mediated by the Candida cylindracea lipase. 2.2.2-Trichloroethyl butyrate (TCEB) was used as a standard for the rate studies. In the event the acyl donor, trichloroethyl methoxyacetate (TCEMA), accelerated the transesterification reaction with hexan-1-ol by an order of magnitude over that with TCEB. This observation, and the absence of an acceleration with trichloroethyl methoxypropionate (and ethyl 2- fluorobutyrate over ethyl butyrate) suggested that the effect is due to the ~oxygen. A solvent activity profile indicated that the most hydrophobic solvents supported faster initial rates. This was attributed to the ability of the hydrophilic solvents to strip the hydrated water from the enzyme surface thus deactivating it. The switch to organic solvents allowed a wider temperature range to be studied. For the reactions between heptan-2-ol and TCEMA the reaction could be conducted in the temperature range -23 C to 80 C. It was of interest to assess how the alcohol moiety effected the transesterification reaction. A series of alcohols were presented to the enzyme and a pattern emerged with substrates containing an acetylene functionality being processed faster than those with a vinyl group, which were faster than those containing a methyl group (all other groups being the same). A series of heterocyclic alcohols were presented to the enzyme and it was observed that the order of reaction was thiophene > furan > pyridyl. The secondary alcohols in this series, 2-thiopheneethan-1-ol and o pyridylethan-1-ol, were resolved at various temperatures from -1soc to sooc with no variation in. enantioselectivity. These are the first resolutions to be accomplished at temperatures below zero degrees.

Biodiesel is primarily produced by transesterification of edible oils. Increasing concern about using food supplies for fuel has generated interest in alternative raw materials. Furthermore, there are numerous steps between harvesting of oilseeds and final production of biodiesel that can be integrated, thereby simplifying the process and making it more suitable for distributed production. Hence, in this study, the production of biodiesel via in situ transesterification of non-edible Jatropha curcas seed has been investigated. The main aim was to investigate the parameters of the process, with a view to reducing the substantial excess of methanol required. A significant secondary aim was to investigate the possibility of utilising other compounds that come out from the process. “Design of experiments” was employed to study the parameters at lab-scale, with the matrix boundary being determined beforehand using one-at-a-time experiments. The reduction of methanol excess was attempted by use of two co-solvents, hexane and diethylmethane (DEM), and by replacing methanol with methyl acetate. It was found that in situ transesterification run using particle sizes below 0.71 mm, a 400:1 molar ratio of methanol to oil, 60 minutes, and a minimum of 300 rpm mixing intensity yielded the highest biodiesel yield of 83 wt %. NaOH concentration and reaction temperature were not found to be significant variables, and were set at 1.0 N and 30oC respectively. DEM was a more effective co-solvent than hexane. The addition of DEM to the process at 400:1 molar ratio experiment increased the yield from 83 to 92 wt %. When methyl acetate was used to replace methanol, the requirement of molar ratio of solvent:oil reduced significantly to 175:1 to achieved 86.8 wt% of biodiesel. The solid meal was shown to contain substantial amounts of protein, making it a valuable co-product stream. Previously J. curcas meal had had little value as animal feed due to its toxicity, but this may be reduced or removed by this process.

Blends of Poly(ethylene terephthalate) (PET) and bisphenol-A-polycarbonate (PC) have been made by solution and melt blending and these blends were subject to isothermal heating to induce a transesterification reaction. The raw materials and products of this reaction have been studied by a variety of different methods to ascertain the chemical, physical and mechanical properties they possess. The conclusions drawn are listed below. PET and PC are immiscible but are compatibilised by transesterification. Transesterification is a second order reversible process and is fast only when water is present, when absent the rate of transesterification is so slow that little or no reaction is observed in after 60 minutes at 300 c. When water is present in the blend significant chain scission and degradation takes place, this is not observed in the absence of water• The material obtained from melt blending has a molecular weight higher than that of commercial PET and it is possible to increase it further by standard solid state polymerization techniques. The PC concentration in PET is critical to the existence and extent of crystallisation. PET blends containing 10% PC are not significantly stronger or weaker than commercial PET and perform very similarly to the yield point. PET blends containing 10% PC are less ductile than commercial PET and will therefore fail sooner when they have yielded under tension. PET blends containing 10% PC do not injection mould as well as commercial PET under conventional procedures for PET, surface crazing and voiding is observed.

Au cours de cette étude, une méthode inédite de fonctionnalisation chimique de la matière lignocellulosique a été développée. Des groupes acyles de taille et de fonctionnalité variées ont ainsi été greffés à l’intérieur du bois, grâce à une réaction de transestérification entre les esters d’énol et les groupes hydroxyles des polymères lignocellulosiques. Les greffages ont été confirmés grâce aux spectroscopies infrarouge et RMN du 13C en phase solide. La stabilité dimensionnelle du bois acétylé à partir de l’acétate de vinyle ainsi que sa résistance aux attaques fongiques a été également évaluée, de même que la photostabilité du bois estérifié à partir des esters de vinyle aromatiques
Abstract

One strain of oleaginous yeasts, Cryptococcus curvatus (ATCC 20509) has been studied to grow on several substrates including biodiesel production byproduct crude glycerol and sweet sorghum juice. After cultivation, yeast cells were heated under microwave radiation to extract lipid and produce biodiesel through in-situ transesterification. Firstly, the yeast growth with crude glycerol was studied. When cultured in a one-stage fed-batch process wherein crude glycerol and nitrogen source were fed intermittently for 12 days, the final biomass density and lipid content were 31.2 g/L and 44.2%, respectively. When cultured in a two-stage fed-batch operation wherein crude glycerol was supplemented at different time points while nitrogen source addition was discontinued at the middle of the experiment, the biomass density was 32.9 g/L and the lipid content was 52% at the end of 12 days. On the second step, an optimization of yeast fermentation with crude glycerol was conducted. Through Box-Behnken design and response surface methodology, the optimal temperature, pH, and glycerol concentration for yeast growth on pretreated crude glycerol was identified as 30.2 deg C, 6.0, and 19.8 g/L, respectively. Adopting these optimal parameters, the biomass density and lipid concentration obtained were 7.11 ± 0.36 g/L and 38.53 ± 1.88%, respectively, which matched well with the model predicted values of 6.98 g/L and 41.31%.The resulting parameters of the response surface method optimization were used in a fed-batch fermentation where crude glycerol was automatically pumped in responding to exhausted oxygen levels in the fermentor. At the end of 12 days, the biomass density and lipid content were 44.53 g/L and 49%,respectively. Compared with our fed-batch experiment which was conducted under un-optimized condition, the yield of biomass and lipid increased 35.26% and 25.29%. When cultured in a fed batch process where sorghum juice syrup was supplemented at different time points for 3 days, the final biomass density was 23.6 g/L with a lipid content of 51%. To extract lipids from cells in an effective and fast fashion, a domestic microwave oven was used with different solvents. With only methanol, a lipid yield of 33.2% of yeast cells was obtained in 4 min. This was comparable with a lipid content of 51% attained through using a traditional solvent extraction approach. In the end, to convert yeast lipids to biodiesel directly without the step of lipid extraction, the in-situ transesterification method used microwave irradiation on the simultaneous extraction and transesterification of wet yeast biomass to biodiesel. Response surface methodology was used to analyze the influence of the process variables (solvent to biomass (v:w) ratio, catalyst concentration, and reaction time) on the fatty acid methyl ester conversion. Based on the experimental results and RSM analysis, the optimal conditions for this process were determined as: methanol to yeast biomass (v:w) ratio of around 50:1, catalyst concentration about 5 wt.%, and reaction time of 2 min. The biodiesel samples were analyzed with GC and the FAME content in biodiesel is about 50%.

Biodiesel is a mixture of an alkyl ester of long chain fatty acids produced by transesterification of triglycerides with lower alcohols such as methanol, in the presence of acid or base catalysts. Nearly all biodiesel processes use homogeneous base catalysts that cannot be recovered and necessitate neutralisation of the glycerol-rich phase (a by- product of the reaction). This increases the number of downstream separation steps, thereby increasing the capital cost of biodiesel production processes. Replacing liquid homogeneous catalysts with solid heterogeneous catalysts can intensify the process, by reducing the total number of process steps, eliminate or reduce waste streams and result in lower production costs, as the catalyst will not have to be continually replaced. Strong anion exchange resins with QN+OR, have the potential to be developed and employed as heterogeneous catalyst for transesterification, as they are chemically stable to leaching of the functional group. In this present work, nine different synthesized anion exchange resins (SIERI-9) were prepared by suspension polymerization of vinylbenzyl chloride-divinylbenzene (YBC-DYB) copolymers in the presence of n- heptane as a pore-forming agent. These SIERs were evaluated as catalysts for transesterification of triacetin. It was found that the "SIER-6" catalyst prepared with the highest dilution degree (200%) and the lowest DYB content (10% DYB), achieved the highest triacetin conversion (95.6% after 4h). This catalyst had the highest true pore volume (0.89 cm3/g) and surface area (398.8 m2/g). In contrast, the "SIER-7" catalyst synthesized with the lowest dilution degree (50%), but highest DYB content (40%), resulted in the lowest triacetin conversion at 64.3%. Although there is a considerable improvement in the physicochemical properties of the IERs, such as surface area, 'true pore' volume and diameter, transesterification using rapeseed oil was rather poor with only 16 wt. % of FAME obtained over SIER-6 after 6h reaction. Overall, the ion exchange resin-catalyzed reaction were well-described by the Eley- Rideal model. Significantly, the ER model data fitted the experimental data for all ion exchange resins studied in this work.

A series of templated [Mg(1-x)Alx(OH)2]x+(CO3)x/n2- with different structural properties have been synthesised using an alkali-free coprecipitation route. The macroporous materials were been obtained using two different kind of templating agents, polymeric materials, in order to cover a bigger size range (750-70 nm). All the materials have been characterized by different techniques: porosimetry, SEM-EDX, TEM-EDX, MP-AES, XRD, CO2 titration before and after the calcinations process. All the materials have been tested for transesterification reaction of C4-C8 triglycerides with methanol for biodiesel production.

Chemistry
Ph.D.
This work describes the application of spiroligomers as serine hydrolases mimetics. Through collaboration with Kendall Houk's group, for the first time in the Schafmeister lab, we demonstrate that "theozymes" can be successfully used as models to design highly functionalized spiroligomer constructs for organocatalysis. We demonstrate a structure-function relationship between the structure of a series of bi-functional and tri-functional spiroligomer based transesterification catalysts and their catalytic activity. First, we designed and synthesized a series of stereochemically and regiochemically diverse bi-functional spiroligozymes to identify the best arrangement of a pyridine as a general base catalyst and an alcohol nucleophile to accelerate attack on vinyl trifluoroacetate as an electrophile. The best bifunctional spiroligozyme reacts with vinyl trifluoroacetate to form an acyl-spiroligozyme conjugate 2.7x103-fold faster than the background reaction with benzyl alcohol. We then incorporated an additional urea functional group to activate the acyl-spiroligozyme intermediate through hydrogen bonds and enable acyl transfer to methanol. The best trifunctional spiroligozyme carries out multiple turnovers and acts as a transesterification catalyst with k1/kuncat of 2.2x103 and k2/kuncat of 1.3x102. Quantum mechanical calculations identified four transition states in the catalytic cycle and provided a detailed view of every stage of the transesterification reaction. With the aim of accelerating the k2, we sought to design better oxyanion holes that hold multiple hydrogen bonding groups in close proximity of the catalytic groups. A macrocyclic motif would be a good candidate to force the oxyanion hole arm to arrange hydrogen-bonding groups in a precise three-dimensional constellation for transition state stabilization. In Chapter 4, we introduce an in silico designed macrocyclic spiroligomer, which overlays well with catalytic active site of an inhibitor bound-esterase. Finally, we detail our effort to develop new methodologies for rapidly synthesizing spiroligomers on solid-support. This would allow us to efficiently permute their structures for diverse applications such as organocatalysts, host molecules, and biologically related applications such as inhibiting protein-protein interactions.
Temple University--Theses

The morphology of poly(ethylene terephthalate)/poly(butylene terephthalate) (PET/PBT) blends before to and after heat treatment have been studied using differential scanning calorimetry (DSC), wide and small angle x-ray scattering (WAXS and SAXS), nuclear magnetic resonance spectroscopy (NMR) and small angle neutron scattering (SANS). Blends with PET/PBT compositions of 100/0, 97/3, 90/10, 60/40, 50/50, 40/60, 25/75 and 0/100%w/w were prepared by precipitation from solutions of the two polymers at the required concentrations. Blends were heat treated to induce ester interchange reactions for a) 6 hours at 476K and b) 1/2 hour at 573K.NMR data showed that the samples iieat treated for 6 hours at 476K were block copolymers and the samples heat treated for 1/2 hour at 573K were random copolymers. DSC, WAXS and SAXS experiments established the morphology of the blends, block and random copolymers. SANS experiments were carried out to study the kinetics of transesterification of PET/PBT copolyesters. Deuterated PET has been synthesised. Data was compared for different molecular weights of deuterium-PET/hydrogenous-PBT blends prior to and after heat treatment to investigate changes in molecular weight of the deuterated chain length as a result of transesterification reactions. From these data it was possible to establish the activation energy of PBT and the results indicate that transesterification reactions take place randomly along the polymer backbone, i.e. by ester-ester interchange.

Biofuels are a developing kind of fuel whose origin is biomass. Among them, many different kind of fuels can be found: bioethanol, biobutanol, biodiesel, vegetable oils, biomethanol, pyrolysis oils, biogas, and biohydrogen. This thesis work is focused on the production of biodiesel, which can be used in diesel engines as a substitute for mineral diesel. Biodiesel is obtained from different kinds of oils, both from vegetable and animal sources. However, vegetable oils are preferred because they tend to be liquid at room temperature.

The process to obtain biodiesel implies first a reaction between the oil and an alcohol, using a catalyst and then a sedimentation, where the biodiesel and the glycerol, the two products that are obtained, can be separated because of their difference in density. After the separation, raw biodiesel is obtained and a treatment with either water bubbling or dry cleaning products is needed to obtain the product which will be ready to use.

Many methods are available for the production of biodiesel, most of them require heat for the transesterification reaction, which converts the oil into biodiesel. Apart from that, in many cases biodiesel is produced by big companies or by individuals but using complicated and expensive installations.

This work is an attempt to develop a way of producing biodiesel without any use of external heat, using a simple procedure which could be used by people with a low knowledge of chemistry or chemical processes. It also seeks to set an example on how biodiesel can be easily made by oneself without the use of any industrial systems, with a low budget and limited need of supervision over the process.

In order to achieve that, many trials were undertaken, introducing changes in the different parameters that are responsible for the changes in the final product. Among them, changes in the amount and type of catalyst, the way the catalyst is added, the type of oil used, the time of reaction and the temperature were made. Apart from that, different types of cleaning were tried, starting by water cleaning and then using powder type products, Magnesol, D-Sol and Aerogel. A centrifuge was also tried to test its utility when separating impurities from liquids or different liquid phases. The results of the different trials were analysed using various tests, the most important being the 3:27 test, the solubility test, the soap titration and pH measurements.

To sum up, it could be said that the investigation was a success, since it was proved that biodiesel can be made without the use of any external heat with both alkali and acid catalysts, as well as with different ways of adding the catalyst. As for the cleaning, good results were obtained with both dry products and water cleaning, since the soap content of the biodiesel was reduced in both cases. Apart from that, the centrifuge proved to be valid to eliminate impurities from raw oil.

Abstract The increasing awareness of the depletion of fossil fuel resources and the environmental benefits of biodiesel fuel has made it more attractive in recent times. The cost of biodiesel, however, is the major hurdle to its commercialization in comparison to petroleum-based diesel fuel. The high cost is primarily due to the raw material, mostly neat vegetable oil. Used cooking oil is one of the economical sources for biodiesel production. However, the products formed during frying, can affect the transesterification reaction and the biodiesel properties. This paper attempts to review various technological methods of biodiesel production from used cooking oil. The analytical methods for high quality biodiesel fuel from used cooking oil like GC, TLC, HPLC, GPC and TGA have also been summarized in this paper. In addition, the specifications provided by different countries are presented. The fuel properties of biodiesel fuel from used cooking oil were also reviewed and compared with those of conventional diesel fuel.

Biodiesel is an attractive alternative fuel for diesel engines.The feedstock for biodiesel production is usually vegetable oil, pure oil or waste cooking oil, or animal fats The most common way today to produce biodiesel is by transesterification of the oils with an alcohol in the presence of an alkaline catalyst. It is a low temperature and low-pressure reaction. It yields high conversion (96%-98%) with minimal side reactions and short reaction time. It is a direct conversion to biodiesel with no intermediate compounds. This work provides an overview concerning biodiesel production. Likewise, this work focuses on the commercial production of biodiesel. The Valdescorriel Biodiesel plant, located in Zamora (Spain), is taken like model of reference to study the profitability and economics of a biodiesel plant. The Valdescorriel Biodiesel plant has a nominal production capacity of 20000 biodiesel tons per year. The initial investment for the biodiesel plant construction is the 4.5 millions €. The benefits are 2 million €/year. The investment is possible to recuperate in less than 3 years. The biodiesel yield can up to 98% with catalyst in excess. The energy used for the biodiesel production is 30% less than the obtained energy from the produced biodiesel. Replacing petro diesel by the biodiesel produced in the plant, the CO2 reduction can reach the 48%. It means that 55 000 tons CO2 per year can be reduced The production of biodiesel from sunflower oil and ethanol using sodium hydroxide as catalyst was performed in the laboratory and the results are discussed. The results are analyzed using the statistic method of Total Quality. The effect of the ethanol/oil ratio and the amount of used catalyst on the yield as well on the properties of the produced biodiesel is studied. The measured properties of the biodiesel are density, viscosity and refraction. The ethanol/oil ratio influences on the biodiesel production. The yield of biodiesel increases with the ethanol/oil ratio.  Regarding the influence of the amount of catalyst on biodiesel production in the studied condition is not possible to achieve a definitive conclusion. But a tendency showing an increasing of the biodiesel yield with the amount of catalyst can be appreciated. The study of the evolution of the transesterification during time shows that a reaction time of one hour is sufficient enough in order to reach the highest yield of biodiesel.

In situ transesterification (IST) can potentially reduce the cost of biodiesel production by avoiding the oil extraction and refining stages of conventional transesterification, through the direct reaction of the oilseed with alcohol in the presence of a catalyst. However, a large excess of alcohol is currently required in IST to achieve comparable yields to conventional transesterification. Hence, in this study, methods for improving in situ transesterification of rapeseed for biodiesel production have been investigated. The focal point of this study is to reduce or utilize the excess alcohol. Pre-soaking seeds in methanol and reactive coupling were subsequently attempted. The respective rationales are to reduce the excess methanol requirement, and convert/use the excess methanol in a secondary process. Pre-soaking involved a chemical pre-treatment of the oilseed prior to the transesterification reaction. Pre-soaking was performed with methanol to oil molar ratio (MOMR) of 360:1 at 60°C using a catalyst (NaOH) concentration of 0.1M. A two-level factorial design was used to determine the optimum conditions for pre-soaking. It was found that a biodiesel yield of 85% was obtained for pre-soaking at 360:1 MOMR while the 'un-soaked' biodiesel yield was 75% at 475:1 MOMR. The higher biodiesel yield with 24% reduction in methanol requirement could potentially translate to energy savings in the downstream separation of biodiesel from excess methanol. Reactive coupling (transesterification + a glycerol polymerisation reaction) should increase the equilibrium conversion of biodiesel, whilst generating valuable secondary products. It was carried out in a pressure vessel at 10 bar, 140°C in an inert atmosphere. Polyglycerol was identified in the reaction mixture using FTIR and 1H-NMR. Using a MOMR of 375:1 with catalyst concentration (H2SO4) of 4.8 v/v% at 140°C, a biodiesel yield of 90% and polyglycerol (PG) yield of 10% were observed after 4 hours of reaction. Overall, the material balance indicated that at the end of the reaction, 19% of the unused methanol had been converted to dimethyl ether (DME). This would lead to energy savings in the separation of product. The Central Composite design of experiment for reactive coupling indicated that catalyst concentration was the most significant variable in biodiesel production, whilst molar ratio is significant for both polyglycerol and DME production. Moreover, the study demonstrates the practicality of FTIR online monitoring of IST, which could be valuable for on-line monitoring at industrial scales, where iii traditional off-line GC analysis is time-consuming and ineffective to correct immediate production problems. Furthermore, the online monitoring could be used for "fast IST" of rapeseed to biodiesel to detect the onset of saponification. This work has demonstrated co-production of valuable chemicals with biodiesel production via reactive coupling for the first time. This could be the initial step toward an integrated biodiesel-based bio-refinery.

A single-step, extractive reaction for extraction of lipids such as biodiesel components, omega-3 fatty acids, or other triglycerides from microbial cells was examined. Conventional methods for lipid extraction use toxic solvents, and require multiple steps and long processing times. When the goal is to produce fatty acid methyl esters or FAMEs, the extracted lipids are subjected to a separate transesterification reaction with simple alcohols in the presence of an acid or base catalyst. A simplified, single-step reactive extraction method can be applied that combines the sequential extraction followed by transesterification using acidified alcohols - a process known as in situ transesterification. It was hypothesized that the in situ transesterification could be scaled-up for industrial processing by a systematic understanding of fundamental reaction parameters including temperature, catalyst concentration, and biomass/solvent ratios. The hypothesis was tested using a marine fungus, Schizochytrium limacinum SR21. Growth of SR21 resulted in biomass yields of 0.3g-biomass/g-glycerol and accumulated high amounts of palmitic acid (C16:0, 0.255g-FAME/g-biomass), docosahexaenoic acid (DHA, C22:6, 0.185g-FAME/g-biomass), myristic acid (C14:0) (0.017g-FAME/g-biomass), and pentadecanoic acid (C15:0, 0.012g-FAME/g-biomass). The bulk phase separation characteristics of the FAMEs were evaluated at high biomass concentrations. Recyclability of the acidified methanol in the system was also tested. A significant finding was that automatic phase separation of the FAMEs could be achieved. When FAME concentration reaches critical solubility, 22.7mg-FAME ml-1 methanol, all remaining FAMEs automatically phase separate. After FAME separation, the remaining methanol was recycled and used in subsequent in situ reactions. Upon recycling, greater than 85% of product extraction and recovery was achieved. The kinetics of the transesterification reaction was evaluated under various acid and biomass/solvent conditions. Based on the fundamental reaction mechanism governing the in situ transesterification, a theoretic model was derived to predict the conversion of TAGs into FAMEs. Kinetic parameters were estimated by fitting the experimental data and the resulting model. The model derived closely resembled the observations in this study. Through understanding of the fundamental reaction kinetics and limitations during processing, a new, reliable, and cost-effective system for large scale lipid production can be developed for microbial biomass including oleaginous algae, fungi, and yeast.

Dans le cadre de la synthèse de nouveaux monomères (meth)acryliques, il a été montré que le réactif rona-nirc (2/2/1) possède des propriétés catalytiques dans les réactions de transesterification. Ce catalyseur est plus efficace et plus sélectif que l'alcoolate qu'il contient. Dans une première partie, il a été montré que les réactions catalysées par un NIRC et effectuées en présence de solvant peuvent être efficacement et sélectivement menées à basse température (10c). Dans ces réactions, la nature du solvant de préparation et d'utilisation, ainsi que la nature de l'alcoolate activant du NIRC influencent de façon considérable sa réactivité. Dans une seconde partie, un réactif tbuona-nirc5(2/2/1) sec a été préparé. Ce catalyseur possède des propriétés catalytiques supérieures à celles du catalyseur en solution. Il a été montré que le solvant de préparation du catalyseur sec n'influe pas sur sa réactivité, à l'inverse de la proportion d'alcoolate. Par ailleurs, un NIRC sec permet de réaliser des transesterifications dans des milieux contenant jusqu'à 1000 ppm d'eau et reste très sélectif pour des températures variant de 25c à 60c. Les travaux décrits dans les deux premières parties ont permis de proposer dans une troisième et dernière partie une hypothèse mécanistique qui fait intervenir une matrice d'alcoolates stabilisée par des entités nickel(0)

This report gives a general overview on biodiesel production, its motivations, characteristics and recent developments, mainly focused in the Brazilian case. The Brazilian National Program for Production and Use of Biodiesel (PNPB) launched 2003 created a demand of biodiesel and stimulated the biodiesel production. Biodiesel is being produced from soybean oil, followed by animal fats and cottonseed oil, with palm and castor bean oil contributing in small portions. The biodiesel expansion has impacts on environmental and social issues such as deforestation from soya expansion and a decrease of employment levels due to the high degree of mechanization of the soya harvest. Experimental work was developed, using corn oil, ethanol and NaOH as a catalyst. Experiments were made varying significant parameters to find the optimum reaction temperature, reaction time, catalyst amount and molar ratio between ethanol and corn oil. Besides that, another experiment aimed to describe the yield behavior as a function of the reaction time. The produced biodiesel has been characterized by measurements of density, refraction index and viscosity. The amount of 0.4 wt % NaOH, based on the weight of raw oil, was enough to catalyze the reaction of transesterification effectively. A higher amount of alcohol in excess provides a higher yield at mild temperature conditions. But the higher amount of alcohol used, the higher the amount of alcohol in excess presented in the biodiesel phase which has to be eliminated. An increase of the temperature from 40˚C to 50˚C  does not increase the yield in a considerable way. Thus due to the energy saving it is not recommended to increase the temperature to 50˚C. Regarding the evaluation of the conversion as function of time, a high conversion is obtained after 90 min. An extension of the reaction time from 90 to 150min had no significant effect.

Biofuels are becoming more attractive worldwide because of the high energy demands and the fossil fuel resources that are being depleted. Biodiesel is one of the most attractive alternative energy sources to petroleum diesel fuel and it is renewable, non toxic, biodegradable, has low sulphur content and has a high flash point. Biodiesel can be generated from domestic natural resources such as coconuts, rapeseeds, soybeans, sunflower, and waste cooking oil through a commonly used method called transesterification. Transesterification is a reaction whereby oil (e.g. sunflower oil) or fats react with alcohol (e.g. methanol) with or without the presence of a catalyst (e.g. potassium hydroxide) to form fatty acid alkyl esters (biodiesel) and glycerol. The high-energy input for biodiesel production remains a concern for the competitive production of bio-based transportation fuels. However, microwave radiation is a method that can be used in the production of biodiesel to reduce the reaction time as well as to improve product yields. Sunflower oil is one of the biodiesel feedstocks that are used in South Africa and is widely used in cooking and for frying purposes. This study aims to use microwave irradiation to reduce the energy input for biodiesel production. The effect of various reaction variables, including reaction time (10 – 60 seconds), microwave power (300 – 900 watts), catalyst (potassium hydroxide) loading (0.5 – 1.5 wt%) and methanol to oil molar ratio (1:3 – 1:9) on the yield of fatty acid methyl ester (biodiesel) was investigated. The quality of biodiesel produced was analysed by Gas Chromatography (GC), Fourier Transform Infrared Spectroscopy (FTIR) and viscometry. The FTIR results confirmed the presence of functional groups of the FAME produced during transesterification. The results showed that transesterification can proceed much faster under microwave irradiation than when using traditional heating methods. The interaction between the alcohol and oil molecules is significantly improved, leading to shorter reaction times (seconds instead of hours) and improved diesel yields. The highest biodiesel yield obtained was 98% at 1:6 oil-to-methanol molar ratio for both 1 wt% and 1.5 wt% potassium hydroxide (KOH) at a reduced reaction time (30 seconds). The chemical composition of FAME (biodiesel) obtained from different conditions i contained palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1) and 70% linoleic acid (C18:2). The physical properties (cetane number, viscosity, density and FAME content) of biodiesel produced met the SANS 1935 specification. The energy consumption was reduced from 1.2 kWh with the traditional transesterification to 0.0067 kWh with the microwave transesterification. Microwave irradiation was shown to be effective in significantly lowering the energy consumption for production of biodiesel with good quality for small scale producers.
Thesis (MSc (Engineering Sciences in Chemical Engineering))--North-West University, Potchefstroom Campus, 2013

碩士
國立成功大學
化學工程研究所
81
The polycarbonate (PC) resin can be producedby phosgenationand transesterification processes. Both processes have advantages and disadvantages. Because of environmental concern (toxicity of phosgene) in Taiwan,the transesterification process may be the choice in this location. In our transesterification study ,various catalysts were evaluatedwith changing operating parameters and the reactants ratios to develop the best process for the production of PC.The processes is applied in the synthesis of high performance PC derivatives (such as high Tg , high impact, low water absorption and still retain high transparency). It was found that alkaline catalysts induce side reaction and discolored the polycarbonate.The electron-donor catalysts (eg.4-Dimethyl-aminopyridine、2- Methylimidazole) were found to be excellent catalysts for the transesterification process. These catalysts not only promote polymerization but also minimize discoloration.To maximize polycarbonate heat stability ,the addition of specific antioxidants were found to be effective and the final product has high intrinsic viscosity (I.V)and high degradation temperature. Several PC derivatives with different glass transition temperatures(Tg) were synthesized by varying the main chain structure of polymer with intention of expanding the areas of PC application.

碩士
國立中正大學
化學工程研究所
102
Biodiesel can be prepared from vegetable oil and methanol via trans-esterification using metal alkoxides catalysts. At the conditions: catalyst, 5 wt%; MeOH/Oil mole ratio, 6/1; reaction time, 5 hr; and temperature, 200 C, the conversions were 99.4, 99.2, 97.5, 72.4, 44.7, 39.1 for Ti(OCH3)4, Ge(OCH3)4, Sb(OCH3)3, B(OCH3)3, Al(OCH3)2, and Cu(OCH3)3, respectively. However, notwithstanding its lower activity, B(OCH3)3 is the preferred catalyst, because B(OCH3)3 can be easily recovered with excess MeOH from biodiesel streams for recycling by distillation. Similar to the reaction catalyzed by solid metal oxides, [B(OCH3)4]- and/or (OCH3)- intermediates are formed from the interaction of B(OCH3)3 with methanol, as evidenced by FT-IR. The intermediates, in turn, attach to electron-deficient carbonyl group of the fatty oil, thus forming biodiesel. Without the presence of Na+, the reaction can proceed smoothly without saponification. Thus, B(OCH3)3 can therefore be used advantageously in trans-esterification of waste cooking oil without saponification and wastes treating problems. Since B(OCH3)3 can be formed from the reaction of methanol with boric acid, boric acid can be used as a catalyst instead of B(OCH3)3. Compared with non-catalytic reaction, reaction catalyzed by boric acid presents higher selectivity to FAME. The result suggest that B(OCH3)3 play a role like phase transfer catalysts that facilitate the attachment of methanol to the carbonyl group of mono- and di- glyceride. Solid acid catalyst, such as pellet HY, also do not have waste catalyst treatment problem. The reaction can be promoted by acid sites. However, the reaction is also limited by mass transfer. HY catalysts with different acid and pore characteristics were prepared HY/Al2O3 calcined powder and pelletized by SiO2, Al2O3, and SiO2-Al2O3 binder. XRD and NH3-TPD indicated that more acid sites can be formed amorphous SiO2-Al2O3. However, for HY/Al2O3, the formation of meso-pore with diameter of 4 nm and the exhibition of the much superior FAME selectivity to the other two catalysts suggests the importance of pore characteristics in catalysis; the reaction of tri-glycerides (fatty acid esters) may be facilitated by the formation of macro-pore while that of mono-glycerides by meso-pores. XRD results suggest that the meso-pores are formed from the fragmentation of HY zeolite crystal.

碩士
崑山科技大學
材料工程研究所
100
The fossil fuels is limited, therefore, the development of renewable energy is very important. Biodiesel is defined as the fatty acid methyl esters made by transesterification of a vegetable oil or waste cooking oil. In this research, the use of canola oil as a raw material, through the homogenizer to enhanced transesterification reaction, the use of NaOH catalysis production biodiesel. A kinetic study of the transesterification of cannola oil was conducted under homogenizer at various temperatures and reaction times. In canola oil as raw material, in homogenizer process, the use of NaOH catalytic reaction, the optimum conditions was as follows: molar ratio of methanol to oil is 8:1 with NaOH concentration of 0.75 wt%, rotational speed 7000 rpm, reaction temperature at 60 ℃ and reaction time for 10 min. The conversion of canola oil into biodiesel was achieved 97.93% for 10 min. In this results, the use of canola oil as raw materials, biodiesel conversion are conformed the Taiwan CNS 15072 standard value of 96.5%. In additional, the rate constant increased from 0.127 min-1 increase to 0.353 min-1 with increasing reaction temperature from 55 ℃ to 65 ℃. The results showed that homogenizer rotation speed at 9000 rpm, canola oil-methnaol molar ratio of 8:1, NaOH concentration of 0.75 wt%, reaction temperature at 60 ℃, reaction for 10 minutes, and biodiesel conversion rate of up to 97.93%. Transesterification reaction of the activation energy was 94.72 kJ / mole.

碩士
國立中興大學
生物產業機電工程學系所
99
The purpose of this study was aimed at developing a microwave- assisted transesterification system of biodiesel. The research first conducted and compared different oil transesterification methods such as traditional water-bath heating, ultrasound-assisted and microwave-assisted. The experimental results obtained showed that under 3 min of transesterification processing, the microwave-assisted method was the best with its transesterification conversion rate up to 70.19% while the traditional were only 46.33 and 51.30%, respectively. The microwave-assisted method demonstrated significant improvement of the ability of oil transesterification. Using the microwave-assisted method of pre-esterification test with four initial free fatty acid contents of 3,5,10and15%,the experimental results obtained showed that under 4 min of pre-esterification processing, the conversion rate of free fatty acid of each set reached saturated condition and were between 49.06 and 58.83% at 3 min of microwave irradiation. At the mean time, the set with 3% of initial free fatty acid was reduced to 1.3%,and the result also showed that the microwave irradiation performed high efficiency in oil pre-esterification. During the multistage microwave-assisted pre-esterification test with 15% of the initial free fatty acid, the experimental results obtained showed that the conversion rate of free fatty acid was up to 74.93% at the third stage. It also expressed that the pre-esterificated process with microwave-assisted could effectively reduce the free fatty acid content in oil and could fit the requirement of low free fatty acid in oil for the further alkaline-catalyzed transesterification. In this study, microwave-assisted transesterification system based on the previous fundamental tests and parameters obtained was built. The optimal condition of the system was obtained using the two-factor Response Surface Method (RSM). The experimental results obtained showed that a second order regression equation with coefficient of determination R2 of 95%, and the optimal condition of microwave irradiation time 3 min 20 sec and catalyst amount 1.1% (w/w) with 73% of transesterification was also found. Finally, an automated microwave-assisted transesterification system combined with an evaporated condensation unit and the pressure control function was set up to conduct a single feed operation of oil transesterification. The experimental results demonstrated that a stable reaction phenomenon of the system was obtained and the optimal conversion rate of oil transesterification was also maintained. In the future, the results of pre-esterification previously obtained could be combined in a system used for the oil transesterification with high free fatty acid, and the results obtained in this study could also provide for the reference of related industries.

碩士
國立臺灣大學
生物產業機電工程學研究所
96
Biodiesel is a kind of clean and renewable energy which can be used directly or mixed with fossil diesel as fuel on vehicles. It can be extracted from recycled vegetable oil or animal fat by using blending, diluting, microemulsion, pyrolysis, or transesterification method. Transesterification means that appropriate amount of alcohols and fat are mixed in supercritical condition with various kind of catalyst to produce esters. It is a common process in producing biodiesel. By using all kinds of catalyst, heterogeneous catalyst is relatively environment-friendly and makes a simple process. In this study, soybean oil is mixed with methanol under 60℃ with hydrotalcite as catalyst to investigate the effect of Mg/Al molar ratio and calcination temperature to the conversion. As result, hydrotalcite made at 550℃ and Mg/Al ratio in 3 has the best conversion. Optimal condition of transesterification is at 60℃, 8hrs, Methanol/Oil=15, catalyst of 5%.

碩士
國立中正大學
化學工程所
97
This work is to use the trickle bed reactor(TBR) on the heterogenous catalyst transesterification. First,Calcium carbonate was precipitated into deionized water, and constructed.. The solid was calcined at 900℃ for 4hours.Then the Calcium carbonate solid reduce to Calcium Oxide to be the catalyst of transesterification. In the batch system, by the conditions oil/methanol molar ratio of 1：25, reaction temperature of 70℃, reaction time of 2hours, catalyst dosage 5g, the oil conversion was 70.39%.And use the designed trickle bed reactor to investigate the experimentation parameters.Under the conditions, total reaction time 2 hours, methanol vaporize rate 3.6ml/min, oil rate 16ml/hr (oil/methanol molar ratio in reacor is 1:15), the Calcium Oxide catalyst bed high 20cm, catalyst bed temperature 70℃,nozzle pressure drop 20 psi, the oil conversion was 86.38%。

Submitted in fulfillment for the requirements for the degree of Doctor of Technology: Biotechnology, Durban University of Technology, Durban, South Africa, 2015.
Main focus of this study is to investigate the enzymatic-conversion of microalgal lipids to biodiesel. However, preceding steps before conversion such as drying of microalgal biomass and extraction of lipids were also studied. Downstream processing of microalgae has several challenges and there is very little literature available in this area. S. obliquus was grown in the pilot scale open pond cultivation system for biomass production. Different techniques were studied for biomass drying and extraction of lipids from harvested microalgal biomass. Effect of these drying and extraction techniques on lipid yield and quality was assessed. Energy consumption and economic evaluation was also studied. Enzymatic conversion of microalgal lipids by extracellular and whole cell lipase application was investigated. For both applications, free and immobilized lipases from different sources were screened and selected based on biodiesel conversion. Process parameters were optimized using chosen extracellular and whole cell lipases; also step-wise methanol addition was studied to improve the biodiesel conversion. Immobilized lipase was studied for its reuse. Final biodiesel was characterized for its fuel properties and compared with the specifications given by international standards. Enzymatic conversion of microalgal lipids was compared with the conventional homogeneous acid-catalyzed conversion. Enzymatic conversion and chemical conversion were techno-economically investigated based on process cost, energy consumption and processing steps. Freeze drying was the most efficient technique, however at large scale economical sun drying could also be selected as possible drying step. Microwave assisted lipid extraction performed better compared to sonication technique. Immobilized P. fluorescens lipase in extracellular application and A. niger lipase in whole cell application showed superior biodiesel conversion. The extracellular immobilized P. fluorescens lipase showed better biodiesel conversion and yields than the immobilized A. niger whole cell lipase. Both the enzyme catalysts showed lower biodiesel conversion compared to conventional chemical catalyst and higher processing cost. However, techno-economic analysis showed that, the reuse potential of immobilized lipases can significantly improve the economics. Fewer purification steps, less wastewater generation and minimal energy input are the benefits of enzymatic route of biodiesel conversion. Microalgae as a feedstock and lipase as a catalyst for conversion makes overall biodiesel production process environmentally-friendly. Data from this study has academic as well as industrial significance. Conclusions from this study form the basis for greener and sustainable scaling-up of microalgal biodiesel production process.
D

Tese de mestrado, Química Farmacêutica e Terapêutica, Universidade de Lisboa, Faculdade de Farmácia, 2016
A computational study on the transesterification reaction was conducted aiming to evaluate whether in silico calculations could support the experimental work carried out to develop industrial manufacturing processes of active pharmaceutical substances. Overall energetic balances between raw materials and products as well as between these and intermediate species formed during the transesterification reaction were built and optimized aiming to better visualize the evolution of the relative energy between all the species along the reaction coordinates. Calculated bond lengths, bond angles, dipole moment and relative energy of conformers of n-propanol, a starting material from a simple esterification reaction studied first, reaction between n-propanol and methyl acetate matched experimental values. Additionally, molecular species of the pathway studied for this simple reaction are in agreement with the mechanism disclosed in the literature and also with the pathway generated for another similar simple transesterification reaction studied, the reaction between isopropanol and methyl acetate. Energy data on the base catalyzed transesterification reaction between scopine and MDTG to yield N-demethyltiotropium, the precursor of tiotropium bromide, an anti-cholinergic bronchodilator, confirm the selection of the bases made during the industrial process development work and are in good agreement with the mechanism proposed in the literature precedents for the synthesis of N-demethyltiotropium. Moreover, the in silico study enabled the understanding of the formation of the major process impurity observed during the experimental work as well as provided insights into the formation of three other process impurities. Based on the results of this study it can be concluded that the computational methodology addressed in the study and herein described provides significant support to the experimental process development work allowing to reduce time and resources allocated to develop industrial manufacturing processes for the production of active pharmaceutical substances.
Este trabalho descreve um estudo de química computacional sobre a reação de transesterificação o qual foi realizado com o objetivo de avaliar se os cálculos in silico poderiam contribuir para acelerar o desenvolvimento de processos de fabrico industrial de substâncias farmacêuticas ativas. O estudo computacional focou-se em particular na reação de transesterificação entre a escopina e o MDTG, para formar o N-desmetiltiotrópio, o qual é o precursor do brometo de tiotrópio na via de síntese deste composto. O brometo de tiotrópio é uma substância ativa usada para aliviar os sintomas da asma e da doença de obstrução pulmonar crónica. Este composto relaxa e alarga as vias respiratórias, atuando com um broncodilatador de longa duração. A aplicação da química computacional ao estudo da reação de transesterificação para a síntese do N- desmetiltiotrópio tem como objetivo demonstrar a viabilidade desta metodologia computacional no apoio ao desenvolvimento dos processos industriais de fabrico de substâncias ativas. O desenvolvimento de condições seletivas para a reação entre a escopina e o MDTG envolveu ensaios laboratoriais com várias bases, ensaios com solventes diferentes bem como ensaios a várias temperaturas. O objetivo destes ensaios era escolher a melhor combinação destes três fatores que permitisse minimizar a formação de impurezas e em simultâneo converter o máximo possível as matérias-primas no produto desejado. Neste estudo computacional avaliaram-se os balanços energéticos entre as matérias-primas e os produtos bem como entre estes e as espécies intermédias que se formam durante a reação de transesterificação. Para uma melhor visualização dos balanços energéticos elaboraram-se esquemas entre matérias-primas, reagentes e produtos onde se evidenciou o balanço energético passo a passo. Construíram-se também diagramas de energia com todas as matérias-primas, espécies intermédias e produtos, para ilustrar a evolução da energia relativa entre os vários compostos ao longo das coordenadas da reação. O estudo envolveu numa primeira fase a avaliação dos vários mecanismos possíveis para a reação de transesterificação, nomeadamente, os mecanismos envolvidos na catálise básica e na catálise ácida. Os mecanismos descritos na literatura para a reação de transesterificação são i) o mecanismo concertado, ii) o mecanismo que envolve a formação do intermediário tetraédrico e iii) o mecanismo que envolve a formação do catião acílio. Neste trabalho começou-se por estudar dois exemplos simples de transesterificação, a reação entre o acetato de metilo e o npropanol e a reação entre o acetato de metilo e o isopropanol. Para o efeito elaboraram-se estruturas moleculares semelhantes às divulgadas em estudos de modelação molecular e na literatura de química orgânica para a transesterificação entre compostos similares. Os resultados obtidos estão de acordo com os estudos referidos e mostraram que o mecanismo da reação de transesterificação nos exemplos estudados passa pela formação de um intermediário tetraédrico. Foi observado in silico o intermediário tetraédrico para cada um dos exemplos citados acima, quer no caso da catálise ácida, quer no caso da catálise básica. Posteriormente, estudou-se o mecanismo envolvido na reação de transesterificação entre a escopina e o MDTG catalisada por base. Elaboraram-se estruturas moleculares comparáveis às descritas na literatura para os exemplos mais simples e estudaram-se os mecanismos associados a estas estruturas. Os cálculos computacionais mostraram que esta reação segue um mecanismo de adição-eliminação que passa pela formação de um intermediário tetraédrico. Este é um dos mecanismos descritos na literatura para a reação de transesterificação catalisada por bases. Para efeitos de comparação com o trabalho experimental efetuado durante o desenvolvimento do processo de fabrico do N-desmetiltiotrópio, testaram-se in silico diferentes bases, em fase gasosa e também no solvente escolhido nos ensaios de desenvolvimento do processo de fabrico. Os resultados computacionais obtidos estão de acordo com os resultados laboratoriais. O estudo da formação das principais impurezas na reação de transesterificação entre a escopina e o MDTG foi igualmente efetuado. Foram estudados os balanços energéticos de quatro impurezas bem como os mecanismos envolvidos na sua formação. As quatro impurezas estudadas foram o DTG, a impureza cíclica do MDTG e duas impurezas resultantes da abertura do anel de epóxido da escopina por ação do alcóxido do MDTG, o derivado 7β-hidróxi, designado em inglês por “epoxy opening 1”, e o derivado 6β-hidróxi, designada em inglês por “epoxy opening 2”. A comparação dos balanços energéticos mostrou que a formação da impureza DTG é de longe a energeticamente mais favorável, resultado que está de acordo com a observação experimental de que esta é a maior impureza que se forma na síntese do N-desmetiltiotrópio. O balanço energético e o diagrama de energia das espécies encontradas no estudo in silico evidenciam de uma forma clara que a formação desta impureza é energeticamente muito favorável e permitiram perceber os níveis elevados que se observaram durante os ensaios de desenvolvimento de processos. É de notar que os cálculos computacionais geraram com alguma frequência uma estrutura optimizada que corresponde ao alcóxido do MDTG e a observação deste espécie conduziu à elaboração de um mecanismo para a formação da impureza cíclica do MDTG bem como à elaboração de um mecanismo para a formação das impurezas resultantes da abertura do anel do epóxido da escopina. A impureza cíclica do MDTG foi observada uma vez, num ensaio, e, naquela altura, não se percebeu como é que esta impureza se formou. Por outro lado, as impurezas resultantes da abertura do anel do epóxido da escopina não foram identificadas durante o desenvolvimento do processo de fabrico do N-desmetiltiotrópio. No entanto, no trabalho laboratorial não se identificaram todas as impurezas pelo que, a observação computacional do alcóxido do MDTG, sugeriu a possibilidade destas impurezas se formarem durante a síntese do N-desmetiltiotrópio e sugeriu igualmente um mecanismo possível para a sua formação. Estes exemplos ilustram bem como a química computacional pode conduzir a um conhecimento mais profundo das reações bem como pode sugerir caminhos possíveis para a formação de produtos secundários das reações. A sugestão de estruturas moleculares plausíveis para explicar mecanismos de formação de compostos está na génese da modelação molecular e o trabalho apresentado nesta tese pretende dar um contributo para a aplicação da química computacional e da consequente modelação molecular no desenvolvimento industrial de processos de fabrico de substâncias farmacêuticas ativas.
Hovione FarmaCiencia SA

碩士
大仁科技大學
環境管理研究所
98
Microalgae, due to the advantages of higher photosynthetic efficiency, higher biomass production and faster growth compared to other energy crops, as a potential source of bioenergy has attracted wide attention. Microalgae are photosynthetic microorganisms that convert sunlight, water and carbon dioxide to algal biomass. Many microalgae are exceedingly rich in lipid, which can be converted to biodiesel. To understand the effect on the biodiesel production via transesterification of microalgae, four factors such as such as alkaline catalyst amount, reaction temperature, reaction time, and acid catalyst amount were investigated using two level four factor full factorial design in this study. Under experimental range considered the most important factor on the biodiesel production of transesterification is the alkaline catalyst amount. For the biodiesel production of biomass, this factor has a positive influence, resulting in an increase of fatty acid content. The reaction time and acid catalyst also have a positive influence respectively. The reaction temperature, however, has a negative influence. There is an appreciable interaction between alkaline catalyst amount (variable 1) and reaction temperature (variable 2), the effects of these variables must be considered jointly. The best results for laboratory scale tested on the biodiesel production via transesterification were obtained at dosage of 8 meq alkaline catalyst, with acid catalyzed, 100℃of reaction temperature, and 30 min of reaction time.

Heterogeneous catalytic reactions that involve immiscible liquid-phase reactants are challenging to conduct due to limitations associated with mass transport. Nevertheless, there are numerous reactions such as esterification, transesterification, etherification, and hydrolysis where two immiscible liquid reactants (such as polar and non-polar liquids) need to be brought into contact with a catalyst. With the intention of alleviating mass transport issues associated with such systems but affording the ability to separate the catalyst once the reaction is complete, the overall goal of this study is geared toward developing a catalyst that has emulsification properties as well as the ability to phase-transfer (from liquid-phase to solid-phase) while the reaction is ongoing and evaluating the effectiveness of such a catalytic process in a practical reaction. To elucidate this concept, the transesterification reaction was selected. Metal-alkoxides that possess acidic and basic properties (to catalyze the reaction), amphiphilic properties (to stabilize the alcohol/oil emulsion) and that can undergo condensation polymerization when heated (to separate as a solid subsequent to the completion of the reaction) were used to test the concept. Studies included elucidating the effect of metal sites and alkoxide sites and their concentration effects on transesterification reaction, effect of various metal alkoxide groups on the phase stability of the reactant system, and kinetic effects of the reaction system. The studies revealed that several transition-metal alkoxides, especially, titanium and yttrium based, responded positively to this reaction system. These alkoxides were able to be added to the reaction medium in liquid phase and were able to stabilize the alcohol/oil system. The alkoxides were selective to the transesterification reaction giving a range of ester yields (depending on the catalyst used). It was also observed that transition-metal alkoxides were able to be recovered in the form of their polymerized counterparts as a result of condensation polymerization subsequent to completion of the transesterification reaction.

碩士
國立成功大學
化學工程研究所
83
Resolution of racemic (±) 1-phenethyl alcohol via PPL(porcine pancreatic lipase) in organic solvents by transesterification with vinyl acetatet was carried out in this investigtion。 Solvent effect on the stereospecificity of the enzyme was investigated。It was found that the reaction rate have a good correlation with hydrophobicity constant log P，and the reaction rate increased with increasing the polarity of solvents 。 PPL at higher temperature stil have good thermal catalysis， this shows that the PPL has a better stability in organ ic solvent than in water。 PPL in water saturated n-heptane have higher reaction rate and lower enantioselectivity than in dehydrated n-heptane。In triethyl amine,howeve,added of water caused the decreasing of PPL activity and the enantioselectivity almost not be affected。 In the presence of chiral polymer TDI-CPO,the reaction system in tetrahydrofurane was found that the reaction rate and the enantiomeric ratio of the system were both increrased。

碩士
大仁科技大學
環境管理研究所
102
Biodiesel (fatty acid methyl esters, FAMEs) is a mixture derived from the esterification and transesterification of free fatty acids (FFAs) and triglycerides and is typically made from renewable biological resources. Microalgae are a source of triglycerides. Many microalgae are exceedingly rich in lipids and oils, which can be converted into biodiesel. Microalgae not only have higher biomass production and faster growth than those of energy crops, producing many times more oil for biodiesel production than traditional oilseed crops on an area basis, but can also reduce the amount of global warming gases and consume other pollutants. Microalgal oils suitable for making biodiesel are common. Four main synthetic approaches have been used for biodiesel production, namely dilution, microemulsion, pyrolysis, and transesterification. The most commonly used method for converting microalgal oils to biodiesel is transesterification. The transesterification reaction is an important step in the overall process of biodiesel production, which is both energy- and cost-intensive. Several factors influence the transesterification reaction. Transesterification can be catalyzed by both alkali and acid catalysts. The alkali catalysis reaction is about 4,000 times faster than the acid catalysis reaction. However, the performance of alkali catalysts is strongly affected by the presence of FFAs in the feedstock. In the present study, one of the dominant green microalgal species, Monoraphidium sp., isolated from local source water was cultured in BG-11 medium. The dried algal biomass was used for biodiesel production. The objectives of this study firstly are to understand the effect of the factors including alcohol quantity, reaction temperature, reaction time, and catalyst concentration on FAMEs yield. An experimental design is implemented to examine the effects among the factors, namely alcohol quantity, reaction temperature, reaction time, and ultrasound radiation that affect the FAMEs yield from microalgal biomass. Due to biomass drying has been demonstrated to be one of the most important economic steps in the microalgae production process, this study therefore also aims to evaluate the FAMEs yield of the wet microalgae biomass among the four transesterification process in order to reduce the biomass drying requirements. The results indicated that the highest FAMEs yield of Monoraphidium sp. was obtained at an alkali catalyst amount 0.5 % NaOH/MeOH of 18 mL, a reaction temperature of 60 °C, and a reaction time of 30 min, while the highest FAMEs yield obtained at a 18 mL acid catalyst amount containing 2 % H2SO4/MeOH, a 60 °C reaction temperature, and a 80 min reaction time for the acid catalysis reaction. Under the experimental range considered, the significant factors for FAMEs yield are the methanol quantity, reaction time, and reaction temperature for both alkali and acid catalysis process. The FAMEs yield increased with decreasing moisture of wet microalgae biomass. However, no significant difference in FAMEs yield affected by moisture of wet microalgae biomass was found when reaction with suitable catalyst amount was adopted. The highest FAMEs yield of wet microalgae biomass was obtained at a 25 mL acid catalyst amount containing 0.5 % NaOH/MeOH and 2 % H2SO4/MeOH respectively. Furthermore, it was observed that alkali-acid-catalyzed transesterification led to a higher FAMEs yield than that obtained only alkali or acid catalyzed transesterification.

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.

碩士
國立高雄大學
化學工程及材料工程學系碩士班
98
Miscibility and Tranesterification of the Poly(butylene adipate-co-butylene terephthalate)/Poly(bisphenol A carbonate) (P(BA-coBT)/PC) blends were investigated by differential scanning calorimetry (DSC)、optical microscopy (OM)、Fourier transform infrared spectroscopy (FT-IR)、scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR). In order to understand properties of P(BA-co-BT)/PC blends, miscibility, thermal behavior, and transesterification of the homopolymers blends, poly(1,4-butylene adipate)/poly(bisphenol A carbonate) (PBA/PC) and poly(1,4-butylene terephthalate)/ poly(bisphenol A carbonate) (PBT/PC) blends were also investigated in the study. The result of phase morphology and thermal analyes revealed that the P(BA-co-BT) and PBA/PC exhibited a homogeneous phase and a composition-dependent glass transition temperature (Tg), indicating the blends were miscible. In the P(BA-co-BT)/PC blends, the interaction parameterχ12 was -0.149 (for PC crystallization melting) or χ12 was -0.022 ( for P(BA-co-BT) crystallization melting). The PBT/PC blends exhibited a heterogeneous phase and two glass transition temperature (Tg), indicating the blend was immiscible. Moreover, the result of thermal analysis revealed that a homogeneous phase and the glass transition temperature (Tg) increased in the P(BA-co-BT)/PC and PBA/PC blends when it was heated at 260℃ and in the P(BA-co-BT)/PC、PBA/PC and PBT/PC blends when it was heated at 285℃. Apparently, there was a chemical interaction in the P(BA-co-BT)/PC、PBA/ PC and PBT/PC blends after heat treatment. Furthermore, the result of FT-IR and NMR revealed chemical interaction in the P(BA-co-BT)/PC、PBA/PC and PBT/PC blends. In the study, a special dual transesterification was proved in the P(BA-co-BT)/PC blends. The primary transesterification was found between the butylenes adipate segment of P(BA-co-BT) copolymer and the carbonate group of PC when the blends were heated at 260oC. The secondly transesterification was also detected between the butylenes terephthalate segment of the P(BA-co-BT) copolymer and the carbonate group of PC when the blends were heated at 285oC. Finally, the mechanisms of transesterification in the P(BA-co-BT)/PC、PBA/PC and PBT/PC were suggested in the study.

碩士
國立勤益科技大學
機械工程系
102
In this research, the self-made small scale biodiesel transesterification equipment was used to obtain the reaction parameters, which can be applied to design the operation process of a large scale transesterification system. Since the small scale equipment is a batch type, such that the combination of couple batch systems under the same conditions and operation parameters will be able to become large system to get the same transesterification result of biomass oil. Through the series of experiments by using the batch system, the conclusions are as follows: Firstly, with 0.8~1% oil weight of KOH as the catalyst, the proper molar ratio of methanol and oil will be 6:1. Secondly, the best transesterification temperature and operation time will be 55~60℃ and 30 minutes, under which, the crude biodiesel yield rate is high as 86.33%. Thirdly, when temperature at 80~90℃, within 30 minutes, the washing process will be done perfectly. And lastly, the standing time for crude biodiesel and glycerol separation as well as biodesel and waste water are both around 40 minutes. From above results, including inlet and outlet, the necessary time for either transesterification or washing process are 100 minutes. Base on those results, one can design a unified system which may operate continuously, thus, the batch system can be turned into continuous system.

碩士
國立成功大學
化學工程學系碩博士班
101
With the development of technology, the energy consumption has increased day by day. It is necessary to find out the alternative energy of fossil fuel for the energy shortage in the future. It makes possible to strike the balance between sustainability and development since biodiesel is a renewable energy with the advantages such as low emission, nontoxicity, and biodegradation. Thus, it has been considered as a promising alternative of fossil fuel. Biodiesel is a mixture of alkyl esters, which are produced either by transesterification of triglycerides such as vegetable oils and animal fats, or esterification of fatty acid with excess methanol in the presence of catalysts. The catalyst plays an important role in the above reactions. As a result from the advantages of separation and processing, heterogeneous catalyst is chosen in this study. Zeolite Y is chosen as the catalyst in transesterification in this study. Due to the poor catalytic activity without modification, it is modified by ion exchange to increase the activity by the loading of alkali metal. The factors that influence the catalysis of transesterification have been investigated such as alkali sources, loading. In this study, CBV 780 has a better catalytic effect than other kinds of zeolite Y in the most conditions. Moreover, it is also investigated that the catalysis of transesterification in the presence of oleic acid. When the oil contains 5% oleic acid (w/w), it is found that the yield could reach 70% with the catalysis of CBV 780 which is ion-exchanged using 10wt% sodium hydroxide for 30 minutes at pH = 10. Seemingly, it still have a passable yield. Hence, as-prepared catalyst may have the opportunity to the application in transesterification of waste cooking oil.

碩士
大同大學
化學工程學系(所)
98
Biodiesel is a renewable fuel, most commonly produced from transterification of vegetable oils with low molecular weight alcohols using homogeneous catalyst. In homogeneous catalytic reaction, soap formation will hinder the reaction process and also cause environmental pollution. Finally, extra cost for the neutralization, distillation, and washing steps needed to purify the final product is too high for industries. In this study, heterogeneous solid catalyst (K3PO4) was used for transesterification reaction in batch and well-stirred reactor. The experimental design methodology was employed to find the main influencing factors, including reaction temperature, methanol to oil molar ratio, catalyst amount and reaction time. The experimental results show that increasing the reaction temperature has little effect on the biodiesel yield, increasing the molar ratio of methanol to oil or catalyst amount can increase the biodiesel yield. The HPLC analysis results show triglyceride decreases with the reaction time, while diglyceride and monoglyceride increases with the reaction time. The 3-step kinetic model can be used to predict the transesterification kinetic curves satisfactorily.

碩士
崑山科技大學
環境工程研究所
102
In recent years, the amount of the oil is reducing and combustion caused the earth's environmental impact. Therefore, the development of new environmentally friendly renewable fuels become the goal of scientists. Biodiesel can be used to replace petroleum fuels with many advantages, such as, it's biodegradable, non-toxie, low sulfur content and transesterification of low emission of harmful substance. The product of vegetable oil, animal oil, waste cooking oil or other raw materials and alcohols such as methanol, ethanol, named biodiesel (fatty acid methyl ester) and a by-product, glycerol. Promote the transesterification reaction through a homogenizer, and find out the best reaction parameters of manufacturing biodiesel. In study (Ⅰ) by using waste cooking oil as a raw material, and promote it by the transesterification homogenizer, it found the molar ratio of alcohol oil is 9:1, NaOCH3 catalyst dosage 0.75 wt%, homogeneous speed at 7000 rpm and a reaction temperature 65 °C, biodiesel production conversion rate after 8 mins 97.1%, were significantly reduced the time required for high acid value of waste cooking oil. Considerations to the manufacturing time and costs, study (Ⅱ) using a homogenizer rapid synthesis of Ca(OCH3)2 as catalyst analysis the catalyst by using XRD, FT-IR, the results illustrate that homogenizer rapid synthesis of methanol calcium, can effectively shorten the preparation time of the catalyst, and used the methanol cakium as with homogenizer ways to promote transesterification transesterification optimal reaction conditions: molar ratio of 6:1, 4 wt% of Ca (OCH3) 2, homogenizer at 7000 rpm for 1 hour at 65 °C, biodiesel yield of 90.2%. Therefore, Ca (OCH3) 2 has great potential to replace homogeneous catalyst for transesterification, it can also be used in applications other heterogeneous catalytic reactions. In study (Ⅲ), using CaO as basic, microwave heating speed up the reaction of modifying the surface of CaO by using bromooctane, to form a coated catalyst to prolong the activity of catalyst. Using XRD, FT-IR, TGA to analysis the physical and chemical properties of the catalyst shows that, by comparing the conventional methods and the microwave modification methods, microwaving can reduce the preparation time of the catalyst, CaO, but the stability and the alkyl intensity is similar to the conventional methods. On the other hand, microwave heating contribute interaction of the oil, and also increase the conversion rate of biodiesel. Using the waste cooking oil as raw material, under open microwaving to promote the esterification reaction, using bromooctane 5mg/g modify CaO as catalyst, the optimal reaction conditions were: microwave power at 300W, molar ratio of alcohol oil 8:1, 3 wt% of modified CaO, reaction at 65°C for 75 minutes, the rate of conversion of biodiesel is 97.1%. These can effectively manufacture biodiesel from waste cooking oil and comply with the standard value of Taiwan CNS 15072, 96.7%, and also reduce the energy consumption, achieve the purpose of saving energy and carbon.

碩士
明志科技大學
化學工程系生化工程碩士班
105
In this study, direct transesterification with a combination of methanol and a solvent was demonstrated to be promising for the production of biodiesel from black soldier fly larvae (BSFL) biomass. In the solvents tested, n-hexane was identified as the most effective solvent for the reaction, resulting in a significant increase in biodiesel yield compared with the use of no solvent. The direct transesterification using n-hexane as a cosolvent was then optimized to maximize the biodiesel yield. The highest biodiesel yield of 94.14% was achieved at methanol dosage of 8 mL , a solvent dosage of 4 mL, a catalyst loading of 1.2 mL, a temperature at 120 °C, and a reaction time was 60 min. In addition, Using the Design of Experiments to obtained the optimal condition of direct transesterification, the biodiesel yield of 93.28 % was obtained at temperature of 101.6C, reaction time of 90 min, catalyst dosage of 1.67 mL, and methanol dosage of 10 mL.This study suggested that direct transesterification using n-hexane as a solvent could be a promising method for biodiesel production from BSFL and decrease production costs.