Catalytic decarboxylation of fatty acids to hydrocarbons over non-noble metal catalysts: the state of the art

The catalytic decarboxylation of fatty acids to yield hydrocarbons, for use as biofuel as a main target, is a topical reaction in which the main challenge is actually to control the selectivity while using the smallest amount of hydrogen possible (or even better, not using hydrogen at all) in order to optimize cost-efficiency of the process. Herein, the focus is on the non-noble mono-, bi- and tri-metallic catalysts used to carry out this reaction. Historically, several non-noble monometallic catalysts based on Cu, Co, Ni supported on different types of supports were first studied. Among such materials, the Co-based catalysts were not selective, while, Cu-based catalysts were more or less selective to hydrocarbons or to olefins, depending on the support used. Among these three metals, the Ni-based catalysts are the most widely described ones due to their specific ability to promote deoxygenation reactions. Combining Ni to a second metal yielded a synergistic effect toward better catalytic performances, with increases in both conversion and selectivity and also improvement of the resistance of the catalyst to carbon deposit, especially when adding non-noble metals. For future prospects, it appears that the main challenge will be to be able to maintain good catalytic performances under inert gas in solvent-free conditions, in order to yield a fully environmentally friendly and cost-effective process. © 2018 Society of Chemical Industry     

Polyhydroxy fatty acids and their derivatives from plant oils

A novel process for the industrial production of hydroxylated fatty acids involves epoxidation of plant oils and their derivatives, followed by catalytic epoxy ring opening in the presence of water or other hydrogen donors, such as alcohols, diols, and amines. Depending on the starting material, epoxidation followed by opening of the oxirane ring leads to fatty acids that contain vicinal diol groups or to other substituted hydroxylated fatty acid derivatives. As an example for the preparation of a substituted hydroxylated fatty acid derivative, the reaction of epoxidized rapeseed oil with monobutylamine as hydrogen donor is described. Apart from the intended formation of hydroxyl groups with vicinal aminoalkyl groups, partial aminolysis of the ester compound was also observed. Another example describes the reaction of epoxidized rapeseed oil with different molar proportions of 1,4-butanediol as hydrogen donor. Depending on the molar proportion of the hydrogen donor, interesterification, or intermolecular ether formation were observed as side reactions. The properties of various technical hydroxylated fatty acids and their derivatives, prepared according to this novel process, are given, and potential applications of these products are suggested.     

Viscosities of fatty acids, triglycerides, and their binary mixtures

Viscosity data have been obtained as a function of temperature for seven fatty acids (pelargonic, capric, lauric, myristic, palmitic, stearic, and oleic) and four triglycerides (tricaprilin, tripalmitin, tristearin, and triolein) and their binary mixtures at temperatures from above their melting points to 90°C. The viscosity measurements were performed by using Cannon Fenske glass capillary kinematic viscometers. Modified versions of the Andrade equation were used to correlate the kinematic viscosities of pure fatty acids and pure triglycerides. The MacAllister method was used for their binary mixtures. The correlation constants are valuable for designing or evaluating chemical process equipment, such as heat exchangers, reactors, distillation columns, and process piping.     

代谢工程改造解脂耶氏酵母生产脂肪酸及其衍生物

微生物来源的脂肪酸及其衍生物广泛应用于能源、材料和营养化学品等领域,可用于生产航空燃油、聚合物、增塑剂、润滑剂和食品添加剂等。解脂耶氏酵母是一种研究最为透彻的产油脂酵母,具有高产各种脂肪酸及其衍生物的潜力。本文综述了近年来解脂耶氏酵母遗传操作工具的发展,并介绍了通过代谢工程技术改造解脂耶氏酵母生产脂肪酸及其衍生物的进展,在此基础上,展望了通过构建解脂耶氏酵母细胞工厂合成特定脂肪酸及其衍生物的未来发展方向。     

Oxidative decarboxylation of unsaturated fatty acids

Long‐chain internal olefins were prepared by silver(II)‐catalyzed oxidative decarboxylation of unsaturated fatty acids by sodium peroxydisulfate. Similar to saturated carboxylic acids, 1‐alkenes were the major decarboxylation product in the additional presence of copper(II), whereas in the absence of copper(II) alkanes were predominantly formed. In both cases, the internal unsaturation of the fatty acids remained largely intact, although the moderate yields indicated that side reactions occurred to a significant extent. The simple procedure makes this multistep one‐pot reaction useful for the synthesis of a variety of internally unsaturated hydrocarbons. The purified products, almost all of which are prepared for the first time, may serve as reference compounds for studies on the heterogeneously catalyzed decarboxylation of triglycerides and fatty acids in the absence of hydrogen. Practical applications: The products of the chemistry described in this contribution, i.e., unsaturated long‐chain hydrocarbons, provide bio‐based building blocks for further chemical modification toward products which may be applied as (bio)fuels, lubricants, solvents, and polymeric materials.     

Oxidative decarboxylation of toluic acids to cresols

The reported procedure for obtaining cresols from copper salts of toluic acids has been examined and certain improvements in yields have been obtained. It has been found that oxygen is preferable to the use of air in this reaction. The variables, oxygen flow rate, reaction temperature, reaction time and copper oxide concentration have been examined, and the effect on the percentage yields of cresols has been found. In the case of p-toluic acid, the molar yield of m-cresol could be raised to 70 % while the molar conversion was 21–22%. For m-toluic acid the molar yield was considerably lower.     

Synthesis of fatty hydroxamic acids catalyzed by the lipase ofMucor miehei

Biotechnological synthesis of a new class of amphiphilic molecules—fatty hydroxamic acids—was carried out using the lipase ofMucor miehei by reacting hydroxyl amine with the fatty acids in their free or methyl ester form. Concurrently with enzymatic synthesis, chemical synthesis of hydroxamic fatty acids has also been developed by adapting methods that already existed for water-soluble acids. Different parameters were studied to determine the optimum operating conditions: temperature, molar ratio of reagents, quantity of biocatalyst and length of reaction. A general method, whatever the type of fatty acids used, is described.     

Autoxidation kinetics for fatty acids and their esters

The autoxidation kinetics for n-3 and n-6 polyunsaturated fatty acids and their esters, which are collectively referred to as polyunsaturated fatty acids (PUFA), were investigated. Changes in the amounts of unreacted n-6 PUFA during the entire period of autoxidation could be expressed by dY/dt−k ₁ Y(1 −Y), wereY was the fraction of unreacted PUFA,t was the time, andk ₁ was the rate constant. For n-3 PUFA, autoxidation had to be separated into two parts. The first half of autoxidation (Y ≥ 0.5) was expressed by the same equation as above, while the latter half (Y<0.5) relates to dY/dt=−k ₂ Y, wherek ₂ was the rate constant. The apparent activation energies and the frequency factors ofk ₁ andk ₂ were evaluated. The apparent activation energies were in a range of 50 to 60 kJ/mol for bothk ₁ andk ₂. The frequency factor became large as the number of double bonds of PUFA increased.     

Predicting the surface tension of biodiesel fuels from their fatty acid composition

The emergence of biodiesel fuels as diesel fuel substitutes has led to several studies on their properties. Surface tension, which plays a role in atomization, has lacked attention compared to other properties. This paper presents a method to predict the surface tension of biodiesel fuels based on the fatty acid composition. Several binary, ternary, and quaternary mixtures of fatty acid ethyl ester gas chromatographic (GC) standards were prepared, and we found that a mass-average equation predicted the surface tension of these mixtures within ±3.5% of their measured values. Six complex mixtures of fatty acid methyl ester GC standards that simulated typical oils used as biodiesel fuels were also prepared. For these complex mixtures the predicted surface tensions of the mixtures, calculated from a mass-average equation, were 2–6% higher than the measured values. A mass-average equation was developed in which we used a weighted surface tension for the individual components, and we found that this method predicted the surface tension of the simulated oils within ±4.5% of their measured values. Five natural vegetable oils were used to produce biodiesel fuels by the transesterification process. The predicted surface tensions of these fuels were all within ±3.5% of their measured values. The surface tensions of 15 biodiesel types were then predicted, based on their fatty acid composition as published in the literature. These results show that the differences in surface tension between biodiesel types are not the main cause of the reported differences in engine tests.     

不同碱金属乌桕油皂微波极化脱羧成烃类燃料的工艺

不饱和脂肪酸盐微波极化条件下更容易脱羧成烃,本研究分别以氢氧化锂、氢氧化钠、氢氧化钾皂化乌桕油,以不同碱金属乌桕油皂化物和乌桕油为研究对象,在恒定的微波功率下裂解脱羧成烃,通过GC-MS等分析裂解产物,微波能选择性地加热乌桕油皂羧基端,不饱和键在微波极化过程中与碳负离子中间体形成P-?共轭体系,使裂解反应（脱羧、端烯化、异构化和芳构化等）顺利进行。皂化物极性越大,升温速率越快,液体烃类产率越高,脱羧效果越明显,裂解液体的密度为0.825～0.865 g/cm3,黏度为2.10～2.55 mm2/s,与柴油的性质非常相似,从而证明微波极化乌桕油皂脱羧制烃类燃料的可行性。     

Applications of phase-transfer catalytic reactions to fatty acids and their derivatives: Present state and future potential

Phase-transfer catalysts (PTC), which accelerate reactions between liquid(organic)-liquid(water) and liquidsolid heterogeneous states, have been investigated and developed. Several processes with PTC have succeeded in industrial processes involving fatty acids and their derivatives. For example, preparation of fatty alkyl glycidyl ethers, from which fatty alkyl glyceryl ethers and their derivatives can be obtained, has been carried out with PTC. However, some problems remain to be solved. For example, preparation of the fatty alkyl glycidyl ether by a PTC reaction was considered, but typical problems to be solved included: (i) how to reuse or recover the catalysts; (ii) how to control the heterogeneous reaction without obstacles to produce useful chemical materials; (iii) how to satisfy the environmental requirements for the catalysts; and (iv) are there more effective catalysts? We address these problems based on our own experiences with phase-transfer catalytic Williamson ether syntheses of fatty alkyl glycidyl ethers. Moreover, we describe recent developments in phase-transfer catalytic reactions related to oleochemistry, such as transition metal-catalyzed reactions of long-chain olefins in liquid(organic)-liquid(water) or liquid-solid heterogeneous states. Based on these results, we have considered the potential of PTC as a synthetic tool in oleochemistry.     

Preparation of glycol derivatives of partially hydrogenated soybean oil fatty acids and their potential as lubricants

Glycol diesters and mixtures of mono- and diesters have been prepared from methyl esters of partially hydrogenated soybean oil fatty acids and diethylene, dipropylene, neopentyl and triethylene glycols. The catalyst used in these reactions was a mixture of calcium acetate/barium acetate (3∶1, w/w). The reactions were carried out under nitrogen with 0.5% catalyst at temperatures in the range of 190–275°C. Borated esters of mixed mono- and diesters were prepared with 0.33 equivalent of boric acid per 1.0 equivalent hydroxyl group on the ester. Refractive indices, viscosities, and flash and fire points were determined for diesters, mixed mono- and diesters, and mixed diesters and borated esters. The viscosities, flash points and fire points indicate that these esters can be used as a component of lubricating oils. Wear-prevention characteristics of mixed diesters and borated esters indicated that they can be used as antifriction additives in lubricating oils. Lecture presented at the joint meeting of the International Society for Fat Research and the American Oil Chemists' Society in Toronto, May 10, 1992.     

Microbial conversion of linoleic and linolenic acids to unsaturated hydroxy fatty acids

The conversion of oleic acid to 10-hydroxystearic acid with resting cells ofNocardia cholesterolicum (NRRL 5767) has been previously reported. These same microorganisms also convert linoleic and linolenic acids to 10-hydroxy-12c-octadecenoic and 10-hydroxy-12c,15c-octadecadienoic acids, respectively. The reaction occurs best at 35°C and a pH of 6.5. Under optimum conditions, 75–80% of the unsaturated fatty acid substrate is converted to the corresponding hydroxy acid. The hydroxy products were characterized by gas chromatography, gas chromatographymass spectrometry, nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy. Other microorganisms that successfully converted these substrates include another strain ofNocardia cholesterolicum (NRRL 5768) andNocardia sp. (NRRL 5636). Presented at the 82nd Annual meeting of the American Oil Chemists’ Society, Chicago, IL, May 12–15, 1991.     

Density estimation for fatty acids and vegetable oils based on their fatty acid composition

The liquid density of fatty acids can be accurately estimated by the modified Rackett equation over a wide range of temperatures. The modified Rackett equation requires the critical properties and an empirical parameter,Z _RA , for each acid as the basis for computing density as a function of temperature. The liquid density of vegetable oils can be estimated by using mixture properties corresponding to the fatty acid composition and a correction for the triglyceride form. The density prediction is explicitly temperature-dependent.     

Resination and decarboxylation reactions in fusion synthesis of ca-resinates

The reaction steps in fusion synthesis of Ca-resinates include a fast, irreversible resination reaction and a slow decarboxylation of rosin acids. The kinetics of the reactions was studied separately in a laboratory scale batch reactor. The kinetic data were obtained by acid number titrations and FTIR measurements. Resination was observed to be a fast irreversible reaction in the temperature range 190 to 235°C. Rate equations for the decarboxylation reaction were derived based on plausible mechanistic reaction steps of free and solvating rosin acids. The parameters of the rate equations were estimated for syntheses at different reaction temperatures (265 to 285°C) and the kinetic model was successfully applied to predict the experimental kinetics of rosin acid decarboxylation.     

Cuticular lipids of the booklouse,Liposcelis bostrychophila: hydrocarbons,aldehydes, fatty acids,and fatty acid amides

The booklouse, Liposcelis bostrychophila, is an increasingly common pest of stored food products worldwide. We report here the cuticular lipid composition of this pest (the first report of the hydrocarbons of any member of the Order Psocoptera and the first report of fatty acid amides as cuticular components for any insect). No unsaturated hydrocarbons were present. A homologous series of n-alkanes (C₂₁–C₃₄), monomethyl alkanes (3-, 4-, 5-, 7-, 9-, 11-, 12-, 13- and 15-methyl-) with a carbon chain range of C₂₈–C₄₂, and dimethyl alkanes (3, 7-; 9, 13-; 11, 15-; 13, 17-; 9, 21-; 11, 19-; and 13, 21-); with a carbon number range of C₃₁–C₄₃ were identified. The relative abundances of these hydrocarbons were low, comprising approximately 0.0125% of total biomass. The amides were a homologous series (C₁₆–C₂₂ in chain length), with the major amide being stearoyl amide. In addition to the amides, free fatty acids (C_16:1, C_16:0, C_18:2, C_18:1, and C_18:0 in chain length) and three straight chain aldehydes (C₁₅, C₁₆, and C_17:1 in chain length) also occurred as cuticular components. These findings are discussed in terms of the chemical and physiological ecology of this species.     

Improved lipase-catalyzed incorporation of long-chain fatty acids into medium-chain triglycerides assisted by supercritical carbon dioxide extraction

Displacement of the equilibrium of the lipase-catalyzed interesterification between medium-chain triglyceride (MCT) and long-chain polyunsaturated fatty acid was accomplished by the removal of by-products with continuous supercritical carbon dioxide (SC−CO₂) extraction at 60°C and 100 kg/cm². The incorporation of eicosapentaenoic acid to MCT was appreciably improved by this method and was 1.3 times higher than that of the equilibrium state (47 wt%) that was obtained in a closed system. The immobilizedMucor miehei lipase was stable for more than 180 h in SC−CO₂ at 60°C and 100 kg/cm². Presented at ISF-JOCS World Congress, Tokyo, Japan, September 26–30, 1988.     

I2 as a mild and efficient catalyst in deoxygenation of sulfoxides with thioacetic acid

An effective procedure for deoxygenation of sulfoxides to sulfides using thioacetic acid as a reducing agent and a catalytic amount of I₂ in MeCN at ambient temperature has been developed. Using this protocol, a variety of sulfoxides including benzyl, allyl, alkyl and aryl sulfoxides have been successfully reduced to the corresponding sulfides in excellent yields.     

Lipase-catalyzed reactions involving thia fatty acids and ester derivatives

Enzymatic hydrolysis of synthetic methyl 5-, 9-, and 12-thiastearates in aqueous media withCandida cyclindracea or porcine pancreatic lipases gave the corresponding fatty acids in 70–100% yield. Hydrolysis of the 3- and 4-positional isomers gave only 15–25% of the free thia fatty acids, suggesting discrimination against these isomers by lipases. No lipolysis was achieved with methyl 2-thialaurate under a range of reaction conditions. Esterification of the 3-, 4-, 5-, 9-, and 12-thiastearic acids withn-butanol inn-hexane using Lipozyme (immobilizedRhizomucor miehei) as the biocatalyst gave the corresponding butyl esters in 80–95% yield. Interesterification (acyl exchange) of triolein with methyl 9-thiastearate in the presence of Lipozyme showed the incorporation of 9-thiastearoyl chain at only one of the α-positions of triolein. In the case of methyl 2-thialaurate, no lipase-catalyzed acyl exchange reaction was possible. This study showed that the position of the sulfur atom in thia fatty esters affects the lipase-catalyzed hydrolysis and interesterification reactions.     

液体碳氢燃料蒸汽重整制氢催化剂研究进展

液体碳氢燃料具有能量密度高、氢含量大及便于储存和运输的特点,以其为原料经重整制氢并应用到移动式的燃料电池/加氢站对民用设备及国防武器等具有现实意义。本文首先对液体碳氢燃料蒸汽重整机理进行概述,明确当前催化剂面临的积炭、硫中毒等主要问题,从而指导高性能催化剂的设计和开发;其次,总结了几种典型液体碳氢燃料（汽油、煤油、柴油、焦油、含硫碳氢燃料等）蒸汽重整催化剂的相关进展,对比了不同催化剂在相应工艺条件下的活性及稳定性;最后,归纳了几类蒸汽重整过程强化技术包括等离子体重整、化学链重整、吸附增强重整及反应与分离耦合重整,说明了各类强化技术的优点及存在的不足,提出通过构建高效催化剂与蒸汽重整强化技术耦合有望实现液体碳氢燃料的高效转化制氢。希望本综述能为进一步研究液体碳氢燃料重整制氢提供相关指导。