离子液体催化合成醋酸正丙酯的研究

醋酸正丙酯对多种合成树脂具有优良的溶解能力,常用于有机合成过程和用作涂料、印刷油墨等的溶剂,也是工业上常用的脱水剂。醋酸正丙酯酯化反应通常采用浓硫酸作为催化剂,但存在设备腐蚀严重、副反应多、后处理过程复杂和污染环境等缺点。利用离子液体具有的稳定性好、不挥发、与有机物相容性可调、酸性可调等特性。制备适用于醋酸正丙酯酯化反应的烷基咪唑磺酸盐酸性离子液体催化剂．并对其性能进行了实验考察。实验结果表明：合成的烷基咪唑磺酸盐离子液体pH值只有2左右,其酸性比浓硫酸低很多,但其酯化催化活性高,催化活性稳定,可重复使用,不具有氧化性,腐蚀性小,不水解,不挥发,属于环境友好的新型酯化催化剂,性能优于Lewis酸催化剂。采用烷基咪唑磺酸盐离子液体催化合成醋酸正丙酯,在乙酸与正丙醇摩尔比（物质的量比）为1：1．05,催化剂加量与反应物料质量比为1：9,反应时间为3h的反应条件下,其酯化转化率可达90．0％～97．7％。     

利用棉籽油制备二聚酸的副产物开发生物柴油的研究

以棉籽油制备二聚酸的工业副产物为原料,采用对甲苯磺酸作催化剂进行酯化反应制备生物柴油.试验考察了反应条件对酯化率的影响,试验结果表明:在反应温度为75℃,催化剂用量为脂肪酸质量的8%,醇酸物质的量比为3:1的条件下,反应4h,酯化率可以达到97%.反应后对产物进行减压旋转蒸发,回收甲醇和催化剂.该试验操作方便,催化剂活性高,污染小,酯化率高.     

桐油制备生物柴油的研究

以桐油为原料,研究了高酸值原料油的预酯化工艺条件,以及酯交换反应过程中甲醇加入的方式.对桐油预酯化工艺条件的研究结果表明,在搅拌速度一定的情况下,预酯化工艺的最佳条件为醇油摩尔比7∶1、硫酸用量为1.5%(质量比)、反应温度70℃、反应时间2 h;在研究的四个因素(醇油摩尔比,催化剂浓度,反应温度,反应时间)中,反应温度对酯化反应转化率的影响最大.在酯交换反应过程中,对分批加入甲醇的初步研究结果表明,在醇油摩尔比6 ∶1、KOH浓度 1%(质量比)、反应温度60℃、反应时间1 h的条件下,分两批加入甲醇的收率比一次加入甲醇的收率提高了4%.     

杂多酸催化合成间甲基异丙苯

研究了负载型杂多酸的催化作用下,以甲苯和丙烯为原料进行烷基化反应合成间甲基异丙苯的工艺过程。在固定床反应器中,考察了催化剂活性和工艺条件,在此基础上,进行了催化剂的寿命实验。结果表明:负载型杂多酸催化剂对于甲苯与丙烯的烷基化反应有很好的活性,反应最佳工艺条件为:反应温度140-160℃,空速2-5h-1,苯烯比>5,反应压力1.0-2.5MPa,原料甲苯中的水含量小于100μL/L。催化剂寿命试验进行了2000h,其活性和选择性均无明显变化,丙烯转化率接近100%,甲基异丙苯选择性在91%-95.4%之间,o-IPT的相对百分含量保持在3.7%上下。证明催化剂具有很好的活性和稳定性,具有良好的工业化前景。     

低酸价菜籽油一步法制备生物柴油工艺的研究

以低酸价菜籽油为原料,采用一步法工艺制备生物柴油,对低酸值原料的酯化-醇解反应进行了考察及分析.试验结果表明,加入适量的水有利于酯化-醇解耦合过程的进行.在对产物组成进行分析和计算的基础上,提出了耦合反应过程的机理,并得出反应的最佳工艺条件:水的加入量为菜籽油质量的2.5%,催化剂加入量为菜籽油质量的1%,98%浓硫酸加入量为菜籽油质量的1%,醇油物质的量比为4:1,反应时间为5.5 h,最高反应温度为93℃.在以上条件下,脂肪酸甘油脂转化率达95%以上.     

稀土固体超强酸SO42-/SnO2-CeO2催化合成生物柴油

以工业棕榈酸和甲醇为原料,采用溶胶-凝胶法制备稀土固体超强酸催化剂SO42-/SnO2-CeO2,催化合成生物柴油。考察了稀土氧化铈添加量、焙烧温度、焙烧时间、硫酸浓度、醇酸质量比、催化剂用量和反应时间对酯化反应的影响。结果表明,当氧化铈添加量为5%时,在2.0 mol/L硫酸浸渍后,于550℃下焙烧3 h制备的催化剂性能最好。正交试验结果表明,合成生物柴油的优化条件为醇酸质量比为15∶25,催化剂用量为棕榈酸质量的4%,反应时间为4 h,在此条件下,酯化率为95.4%。经GC-MS分析,酯产物主要为直链十六烷酸甲酯和10-十八碳烯酸甲酯。     

大豆酸化油制备生物柴油的研究

试验研究了大豆酸化油在复合酸催化剂的作用下与甲醇发生转酯化和酯化反应生成脂肪酸甲酯(生物柴油)的最佳反应条件.试验结果表明,该酯化及转酯化反应的最佳操作条件:复合酸催化剂的用量为大豆油质量的5%、油醇摩尔比为1:6、反应时间为6h、反应温度为65℃.     

生物柴油精细化学品-蔗糖酯合成技术研究

以生物柴油和蔗糖为原料,在N2保护下采用无溶剂法合成蔗糖酯,以活性炭负载的碳酸钾为催化剂,确定了蔗糖酯合成技术的各项工艺条件:生物柴油与蔗糖的物质的量比为2∶1,在N2保护下,催化剂活性炭负载碳酸钾加入量为总物料量的6%,助溶剂硬脂酸钾加入量为15%,在135℃下反应3h,采用溶剂萃取法纯化粗产物,精制后的蔗糖酯产率以蔗糖记为86.4%。     

高酸值油料一步法制备生物柴油研究

以酸值123.04 mg KOH/g的棕榈油脱臭馏出物(PFAD)为原料,在带压反应器中,用浓硫酸为催化剂,采用一步法催化酯化反应制备生物柴油。重点研究反应温度、反应时间、催化剂用量和醇油比等因素对酯化和酯交换反应的影响。结果表明,提高反应温度能促进酯化反应和酯交换反应,使高酸值原料经一次反应直接转化为目的产物——脂肪酸甲酯,从而缩短制备流程,降低成本,强化酯化反应进行,提高脂肪酸甲酯收率。当催化剂用量为0.5%(质量分数)、醇油物质的量之比7∶1、在130℃反应90 min后,生物柴油的最高收率达到88.1%。较之酸碱两步法催化高酸值油料制备生物柴油能显著缩短反应时间、简化工艺流程、降低生产成本。     

旋转锥式反应器催化大豆油裂解制备可再生燃料油

采用自制的转锥式催化裂解反应器,研究了以大豆油为原料制备可再生液体燃料油的技术.考察了催化剂的种类、裂解温度、加料速度等反应工艺条件对裂解产物性能的影响.研究结果表明:催化裂解反应的优选工艺条件为氢氧化钾作为催化剂,反应温度为450-500℃,滴加速度为50g/h,液体燃料收率为78.3%.气质联用和红外光谱分析表明,...     

Synthesis and characterization of monk fruit seed (Siraitia grosvenorii)-based heterogeneous acid catalyst for biodiesel production through esterification process

This research investigated for the first time the synthesis of monk fruit seed (Siraitia grosvenorii)-based solid acid catalyst for biodiesel production. The catalyst was synthesized using a two-step surface functionalization method with trimethoxy phenyl silane and chlorosulfonic acid. The as-synthesized catalyst was characterized to ascertain its catalytic characteristics through surface morphology, chemical bonding, and thermal stability. The effects of activating agent impregnation ratio, carbonization temperature, and sulfonation temperature towards fatty acid methyl ester (FAME) yield were elucidated. The esterification reaction with palmitic acid was found to produce FAME yield up to 98.5% with 4 wt.% catalyst loading, 6-h reaction duration and 120°C reaction temperature. The catalyst also demonstrated high reusability with 84.4% FAME yield being successfully maintained after four successive cycles without reactivation. These proved that the as-synthesized catalyst had high prospect to become a suitable low-cost alternative for biodiesel production through catalytic esterification process in the future.     

A green sulfonated carbon-based catalyst derived from coffee residue for esterification

A green sulfonated carbon-based catalyst was successfully synthesized through sulfonation of incompletely carbonized coffee residue (SCAC catalyst). The sulfonation temperature was investigated and the catalytic activity was tested via esterification of caprylic acid. SCAC-200, the highest caprylic acid conversion at 4 h (71.5%) and initial TOF based on SO₃H acid sites, was synthesized under a carbonization temperature of 600 °C for 4 h and sulfonation temperature of 200 °C for 18 h. Sulfonation temperature plays a dominant role in determining the SO₃H site density of SCAC catalysts because side reactions (condensation/oxidation/dehydrogenation) take place at high sulfonation temperature as indicated by oxygen-to-carbon surface ratio. The activities of the SCAC catalysts were also substantially greater than that of Amberlyst-15. A high catalytic activity and catalyst stability for esterification of HCp were achieved in the SCAC catalysts with high surface area and by balancing strong (SO₃H) and weak (carboxylic and phenolic) acid site densities. Additionally, this catalyst could be regenerated to obtain essentially its initial catalytic activity by MeOH washing. Therefore, the sulfonated coffee residue derived catalyst is promising, economic eco-friendly and potentially substituted for homogeneous H₂SO₄ catalyst for esterification in industries in the near future.     

Kinetic model for the esterification of oleic acid catalyzed by zinc acetate in subcritical methanol

The esterification of oleic acid in subcritical methanol catalyzed by zinc acetate was investigated in a batch-type autoclave. The effect of reaction conditions such as temperature, pressure, reaction time and molar ratio of oleic acid to methanol on the esterification was examined. The oleic acid conversion reached 95.0% under 220 °C and 6.0 MPa with the molar ratio of methanol to oleic acid being 4 and 1.0 wt% zinc acetate as catalyst. A kinetic model for the esterification was established. By fitting the kinetic model with the experimental results, the reaction order n = 2.2 and activation energy E_a = 32.62 KJ/mol were obtained.     

正交试验探讨脂肪酸超临界酯化制备生物柴油

探讨脂肪酸在超临界甲醇中酯化反应的规律及最佳条件。以橡胶籽油脂肪酸为原料,在间歇式高温高压反应釜中通过酯化反应制备生物柴油,分别考察了酯化反应条件如反应温度、反应时间、甲醇与脂肪酸的体积比对酯化率的影响。应用正交试验方法得出酯化反应的较适宜条件为：反应温度290℃,反应时间30min,甲醇与脂肪酸的体积比为4：1。在此反应条件下转化率可达99．2％。橡胶籽油生物柴油成分主要有亚油酸甲酯、油酸甲酯、亚麻酸甲酯,还有少量的硬脂酸甲酯、棕榈酸甲酯。     

Preparation of silver-exchanged heteropolyacid catalyst and its application for biodiesel production

ABSTRACT

In this study, the silver-exchanged heteropolyacids were prepared by a simple and environmentally friendly ion exchange method, were found to be active in the esterification of oleic acid with methanol to produce biodiesel. The catalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and scanning electron microscopy (SEM), separately. The effect of various factors was investigated to optimize the reaction conditions. The results showed that the oleic acid conversion can reach 91.3% after reacting for 3 h at 70°C, with oleic acid to methanol ratio of 1:10 and the amount of catalyst of 5 wt.%. Moreover, the catalyst could be easily separated from the reaction mixture and used repeatedly for five cycles with the oleic acid conversion over 50.1%, due to its relative stability. In particular, this catalyst can also catalyze other esterification of fatty acids with different chain length of carboxylic acid and high acid value non-edible oils, which may provide significant benefits for developing an environmentally benign and continuous process for synthesizing biodiesel in the future.     

Bio-oil catalytic reforming without steam addition: Application to hydrogen production and studies on its mechanism

A novel process for hydrogen production via bio-oil catalytic reforming without steam addition was proposed. The liquid feedstock was a distillation fraction from crude bio-oil molecular distillation. The fraction obtained was enriched with the low-molecular-weight organics (acids, aldehydes, and ketones), and contained nearly all of the water from crude bio-oil. The highest catalytic performance, with a carbon conversion of 95% and a H₂ yield of 135 mg g⁻¹ organics, was obtained by processing the distillate over Ni/Al₂O₃ catalyst at 700 °C. The steam involved in the reforming reaction was derived entirely from the water in the crude bio-oil. The fresh and spent catalysts were characterized by N₂-physisorption, thermogravimetric analysis, and high-resolution transmission electron microscopy. To further understand the reaction mechanisms, symmetric density functional theory calculations for decomposition were performed on four model compounds in bio-oil (acetic acid, hydroxyacetone, furfural, and phenol) over the Ni(111) surface. In addition, the decomposition of H₂O∗ to OH∗ and O∗ and their subsequent steam reforming reactions with carbon precursors (CH∗ and CH₃C∗) were also examined.     

Hydrogen production via catalytic reforming of the bio-oil model compounds: Acetic acid,phenol and hydroxyacetone

Catalytic reforming of three typical bio-oil model compounds, phenol, acetic acid and hydroxyacetone, has been carried out over a Ni/nano-Al₂O₃ catalyst. Al₂O₃, in the form of nano-rods of length approximately 40 nm, was selected as the catalyst support. The catalyst showed superior performance in terms of activity and stability. The conversions for phenol, acetic acid and hydroxyacetone reached 84.2%, 98.2% and 98.7%, respectively, at the reaction temperature of 700 °C. The corresponding hydrogen yields were 69%, 87% and 97.2%. The catalyst maintained its high reactivity for more than 10 h in the catalytic reforming of three model compounds. The influences of steam to carbon ratio, catalyst loading and Ni content in the catalyst on the reforming performance were also investigated. In addition, the possible decomposition pathways for phenol, acetic acid and hydroxyacetone are proposed.     

Novel esterification reaction from biomass product by coupled acetate membrane and catalysts for ethyl lactate separation

This study presents the effect of combined membrane separation and heterogeneous catalysts for the production of ethyl lactate solvent. The enhanced process is a flat sheet cellulose acetate membrane and cation-exchange resin catalysts. A methodology based on catalyst and acetate membrane impregnation in the presence of a sweep gas at low pressure with the aim of obtaining a higher yield of the ester product have been developed. The esterification reaction was carried out at the temperature of 60 °C. The ester product gave a percentage yield of up to 75%. The ion chromatogram of the ester product obtained in the catalyst and membrane impregnation was compared with the esterification product of the batch esterification reaction. The gas chromatograph NIST library spectra of the ester product indicated the structure of ethyl lactate (45) on the mass spectra which was in accordance with the commercial ethyl lactate. Products obtained on dowex 50W8x and amberlyst 36 resin catalysts were found to elute faster at 1.503 and 1.527 min respectively in contrast to those using amberlyst 15 and amberlyst 16. In all, the percentage yield of the ethyl lactate can be improved using cellulose acetate membrane. Amberlyst 36 and dowex 50W8x cation-exchange resins were revealed as the most effective catalysts for the esterification process involving lactic and ethanol to produce ethyl lactate in contrast to other cation-exchange resins that were used in the study. The results further confirms effectiveness of cellulose acetate membrane in the selective removal of the water from the esterification product.     

Biodiesel production by esterification of oleic acid over zeolite Y prepared from kaolin

Zeolite Y, with a Si/Al ratio 3.1, was prepared using Iraqi kaolin and tested as a catalyst in the liquid-phase esterification of oleic acid (a simulated free fatty acid frequently used as a model reaction for biodiesel production). XRD confirmed the presence of the characteristic faujasite structure of zeolite Y, and further analysis was conducted using BET adsorption, FTIR spectroscopy, XRF, DLS particle size and SEM. A range of experimental conditions were employed to study the reaction; alcohol/oleic acid molar ratio, temperature, and catalyst mass loading. The optimum conditions for the reaction were observed at 70 °C, 5 wt% catalyst loading and 6:1 ethanol to oleic acid molar ratio. The oleic acid conversion using the zeolite prepared from kaolin was 85% after 60 min, while the corresponding value for a commercial sample of HY zeolite was 76%. Our findings show that low Si/Al ratio zeolite Y is a suitable catalyst for esterification, which is in contrast to the widespread view of the unsuitability of zeolites, in general, for such applications.