An integrated reactive distillation process for biodiesel production

An integrated reactive distillation process for biodiesel production is proposed. The reactive separation process consists of two coupled reactive distillation columns (RDCs) considering the kinetically controlled reactions of esterification of the fatty acids (FFA) and the transesterification of glycerides with methanol, respectively. The conceptual design of the reactive distillation columns was performed through the construction of reactive residue curve maps in terms of elements. The design of the esterification reactive distillation column consisted of one reactive zone loaded with Amberlyst 15 catalyst and for the transesterification reactive column two reactive zones loaded with MgO were used. Intensive simulation of the integrated reactive process considering the complex kinetic expressions and the PC-SAFT EOS was performed using the computational environment of Aspen Plus. The final integrated RD process was able to handle more than 1% wt of fatty acid contents in the vegetable oil. However, results showed that the amount of fatty acids in the vegetable oil feed plays a key role on the performance (energy cost, catalyst load, methanol flow rate) of the integrated esterification–transesterification reactive distillation process.     

Hydrogen bond induced acidic liquids for efficient biodiesel production

In chemical engineering, the Fischer–Speier esterification shows incredible value for biofuel production. However, the transformation suffers from challenges including necessary catalysts that cause corrosion issues in addition to a complex synthesis. Herein, we report a green acidic liquid, [N,N,N-tris(propanesulfonic)aniline][ethanol]₃, which is induced by hydrogen bonding interactions between a hydrogen bond acceptor (HBA) of [N,N,N-tris(propanesulfonic)aniline] and three hydrogen bond donators (HBD) of ethanol, through a one-step reaction. This liquid demonstrates strong Bronsted acidity and hydrogen bond networking to mimic ionic liquids (ILs) or deep-eutectic solvents (DESs). Even under mild conditions, biodiesel was produced with 97.65% of esterification conversion. Exploiting distinguished molecular geometry with a singular methodology, made possible by contributions from HBD, allows for a further reaction of 1,3-propanesulfonate with positively charged amines. This discovery is feasible with a wide range of HBDs as a solvent resulting more commercially accessible products owing to a much greener synthesis when compared with ILs and DESs.     

酸离子液体中制备生物柴油组分酯化反应动力学

以4类不同含氮官能团及不同阴离子的B酸离子液体为催化剂,研究了油酸甲酯的酯化反应动力学。通过反应动力学实验,利用Matlab程序,将实验数据回归拟合,确定反应动力学参数,建立动力学模型,并对不同离子液体催化剂活性进行评价。结果表明,不同酸离子液体催化剂作用下,油酸甲酯酯化反应动力学方程为:r=k(c_(A0)-x)~(1.72)(c_(B0)-x)~(2.01)-k_(-1)x~(1.85)。9种离子液体催化体系的正向反应速率常数k顺序为:[MPy]HSO_4[Py]HSO_4[Et_3NH]HSO_4[MPy]H_2PO_4[Py]H_2PO_4[Et_3NH]H_2PO_4[HMIm]HSO_4[HMIm]H_2PO_4[MPy]NO_3。     

An enzymatic/acid-catalyzed hybrid process for biodiesel production from soybean oil

The present study is aimed at developing an enzymatic/acid-catalyzed hybrid process for biodiesel production using soybean oil as feedstock. In the enzymatic hydrolysis, 88% of the oil taken initially was hydrolyzed by binary immobilized lipase after 5 h under optimal conditions. The hydrolysate was further used in acid-catalyzed esterification for biodiesel production and the effects of temperature, catalyst concentration, feedstock to methanol molar ratio, and reaction time on biodiesel conversion were investigated. By using a feedstock to methanol molar ratio of 1:15 and a sulfuric acid concentration of 2.5%, a biodiesel conversion of 99% was obtained after 12 h of reaction at 50 °C. The biodiesel produced by this process met the American Society for Testing and Materials (ASTM) standard. This hybrid process may open a way for biodiesel production using unrefined and used oil as feedstock.     

强化技术在生物柴油制备过程中的应用研究进展

在生物柴油生产过程中,由于原料油与醇不互溶,导致生物柴油生产过程中酯交换速率低,影响了生产效率。本文从强化反应过程、提高反应速率方面对以下几种强化手段进行了综述和比较：机械搅拌法、共溶剂法、超临界流体法、超声波法、水力空化法、微波法。指出水力空化设备简单,安全、高效,放大可靠,可连续化生产、工业前景良好。     

Effects of process variables for biodiesel production by transesterification

In this study, biodiesel production from various vegetable oils by transesterification was studied, to determine the optimum conditions. Experiments were carried out by using different kinds of catalysts (sodium hydroxide, potassium hydroxide, barium hydroxide, pyrolitic coke and wood ash) and feedstocks (corn oil, sunflower oil, soybean oil, olive pomace oil and cottonseed oil) at 65 °C and an agitation speed of 1000 rpm. The neutralization step with controlled pH was performed by treatment with phosphoric acid. An experimental design was used to evaluate the effects of the parameters such as types of vegetable oils, kinds of catalysts, reaction time, alcohol/oil volumetric ratio and amount of catalyst, on the methyl ester conversion. Using response surface methodology, a quadratic polynomial equation was obtained by multiple regression analysis. It was found that catalyst concentration was the most effective parameter. Sodium hydroxide and potassium hydroxide exhibited a superior catalytic behavior, whereas pyrolitic coke and wood ash had to be used in excess amount or for prolonged reaction times. Moreover, the properties such as viscosity, density, calorific value, acid value, and refractive index of the biodiesel were measured. The tri‐, di‐, monoacylglycerols and glycerol residuals in the methyl esters produced were also quantified by GC analysis.     

An ionic liquid reaction and separation process for production of hydroxymethylfurfural from sugars

Hydroxymethylfurfural (HMF) is viewed as a potential platform material to make a variety of chemicals and products out of renewable resources. In this work, a complete ionic liquid reaction and separation process is presented for nearly stoichiometric conversion of fructose into HMF. The silicalite adsorbent material is demonstrated for separation of 99% pure HMF out of ionic liquid reaction mixtures through a packed column and for recovery of the unconverted sugars and reaction intermediates along with the ionic liquid. Membrane‐coated silicalite particles are prepared and studied for a practical adsorption process with separation performances comparable to or better than the powder material. It is discovered that nearly all the fresh fructose feed could be converted into HMF with the recycled ionic liquid under suitable reaction conditions. These research results lead to a new HMF production process much simpler than the current paraxylene manufacturing process from petroleum oil. © 2013 American Institute of Chemical Engineers AIChE J, 60: 300–314, 2014     

磺酸功能化离子液体的合成及催化制备生物柴油应用

基于4-甲基噻唑,采用两步法合成4种不同阴离子的磺酸功能化离子液体用于催化无患子油与甲醇酯交换反应制备生物柴油。傅里叶红外光谱、核磁共振和热重分析结果表明,离子液体被成功制备并且具备高热稳定性。其中,3-（3-磺酸基）丙基-4-甲基噻唑三氟甲烷磺酸盐（[Ps-MTH][CF₃SO₃]）在所制备的离子液体中表现出最高的催化活性。以[Ps-MTH][CF₃SO₃]为催化剂,无患子油与甲醇酯交换反应的最佳操作条件为反应温度128℃、醇油摩尔比28.10∶1、催化剂用量0.62 mmol/g（基于油的质量）、反应时间8 h,生物柴油收率高达92.78%±0.47%。此外,[Ps-MTH][CF₃SO₃]具备良好的重复使用性,在不同酯交换反应中也表现出良好的催化活性。该研究为离子液体催化无患子油制备生物柴油的工业化生产提供了基础数据。     

Prospects of non-catalytic supercritical methyl acetate process in biodiesel production

Conventional biodiesel production methods utilize alcohol as acyl acceptor and produces glycerol as side product. Hence, with escalating production of biodiesel throughout the world, it leads to oversupply of glycerol and subsequently causes devaluation in the market. In this study, methyl acetate was employed as acyl acceptor in non-catalytic supercritical methyl acetate (SCMA) process to produce fatty acid methyl esters (FAME) and side product of triacetin, a valuable fuel additive instead of glycerol. Consequently, the properties of biodiesel produced (FAME and triacetin) are superior compared to conventional biodiesel method (FAME only). In this research, the effects of reaction temperature, reaction time and molar ratio of methyl acetate to oil on the yield of biodiesel were investigated. Apart from that, the influence of impurities commonly found in waste oils/fats such as free fatty acids and water were studied as well and compared with methanol-based reactions of supercritical and heterogeneous catalysis. Results show that biodiesel yields in SCMA process could achieve 99 wt.% when the operating conditions were fixed at 400 °C/220 bar for reaction temperature, methyl acetate/oil molar ratio of 30:1 and 60 min of reaction time. Furthermore, SCMA did not suffer from adverse effect with the presence of impurities, proving that SCMA has a high tolerance towards contamination which is crucial to allow the utilization of inexpensive waste oils/fats as biodiesel feedstock.     

Techno-economic analysis of a biodiesel production process from vegetable oils

Biodiesel, which is defined as the monoalkyl esters of long chain fatty acids derived from a renewable lipid feedstock, has received considerable attention worldwide as a medium-term alternative to diesel fuel obtained from petroleum. Biodiesel can be produced by the transesterification of vegetable oils or animal fats using short-chain alcohols in the presence of a suitable catalyst and glycerol is the only byproduct obtained in significant quantities. In this work a techno-economic analysis of a process that produces biodiesel from vegetable oils is presented with the aim to investigate the dependence of the critical profitability indicators on the production capacity.     

酯化-酯交换两步法制备生物柴油的动力学

以潲水油（WCO）为原料,探讨了酯化-酯交换两步法制备生物柴油的反应动力学。以活性炭负载硫酸铁［Fe₂(SO₄)₃/AC］为负载型催化剂,通过测定不同反应温度、不同甲醇/脂肪酸（FFA）摩尔比条件下WCO中游离脂肪酸的转化率,以此确定酯化反应的动力学控制步骤及动力学方程中的待定参数,从而建立了在实验温度范围内酯化反应的动力学方程,并根据碱催化酯交换反应机理,在简化的动力学模型基础上,推导出了WCO中甘油三酯（TG）与甲醇发生酯交换反应的宏观动力学方程。结果表明,酯化反应和酯交换反应的动力学方程在实验条件范围内都能较好地描述各自的反应过程。     

Investigation of enzymatic biodiesel production using ionic liquid as a co‐solvent

In this study, the lipase catalysed esterification reaction for biodiesel production was investigated in the presence of the ionic liquid [BMIM][PF₆]. Unlike regular organic solvents, many ionic liquids have no vapour pressure, and are therefore considered non‐volatile. When used in systems with enzyme catalysts, ionic liquids may enhance their activity, selectivity, and stability. The use of an enzyme (lipase) as a catalyst, and the ionic liquid as a solvent/immobilization agent also represents an environmentally friendly, “green” technology. Methyl acetate was used as the acyl acceptor as opposed to the more commonly used methanol due to the negative effects methanol and the glycerol by‐product has on lipase enzyme activity. The results of this research indicate that methyl oleate (i.e., biodiesel) was successfully produced, with an 80% overall biodiesel yield in the presence of ionic liquid, at a 1:1 ratio (v/v) to the amount of oil. This verified that the presence of an ionic liquid, at a specified amount, improved the activity of the lipase and the overall biodiesel yield. Results also indicate the addition of ionic liquid facilitated the separation of the methyl esters from the triacetylglycerol by‐product. The best conditions investigated was found to be: 14:1 molar ratio between oil and acyl acceptor; 20% (w immobilised lipase/w of oil; and a temperature in the range of 48–55°C. However, additional purification is required in order for the produced biodiesel to meet ASTM standards.     

Extraction,transesterification and process control in biodiesel production from Jatropha curcas

Biodiesel has gained worldwide popularity as an alternative energy source due to its renewable, non‐toxic, biodegradable and non‐flammable properties. It also has low emission profiles and is environmentally beneficial. Biodiesel can be used either in pure form or blended with conventional petrodiesel in automobiles without any major engine modifications. Various non‐edible and edible oils can be used for the preparation of biodiesel. With no competition with food uses, the use of non‐edible oils as alternative source for engine fuel will be important. Among the non‐edible oils, such as Pongamia, Argemone and Castor, Jatropha curcas has tremendous potential for biodiesel production. J. curcas, growing mainly in tropical and sub‐tropical climates across the developing world, is a multipurpose species with many attributes and considerable potentials. In this article, we review the oil extraction and characterization, the role of different catalysts on transesterification, the current state‐of‐the‐art in biodiesel production, the process control and future potential improvement of biodiesel production from J. curcas.     

Hemicelluloses obtaining from rapeseed cake residue generated in the biodiesel production process

The processing of rapeseed oil seeds for biodiesel production generates huge amounts of lignocellulosic cake residue mainly composed by cellulose, hemicelluloses and lignin. In this work, the valorisation of these components, especifically the majoritary fraction, hemicelluloses, was studied. Hemicelluloses were extracted, purified and characterized by different techniques (FTIR, ¹H NMR, ¹³C NMR, and GPC). Autohydrolysis and acid hydrolysis processes were applied to obtain sugar monomers and oligomers. Glucose and xylose were the main simple sugars in the obtained hydrolysates, representing 22.7% and 40.2% of total sugars content in the autohydrolysis hydrolysates and 27.7% and 36.6% in the acid hydrolysates respectively. Arabinose, galactose and mannose were present in relatively minor quantities.     

An overview of solid base heterogeneous catalysts for biodiesel production

The alcoholysis process requires high activity catalysts for biodiesel production. Heterogeneous catalysts have been proven to possess highly active nature and are environment-friendly. The present article emphasizes on various types of solid base catalysts that have been used in the recent past for the production of biodiesel by transesterification of oils. The parameters and conditions affecting the transesterification reaction and biodiesel yield have also been mentioned in the article. Heterogeneous catalysts have the capability to be recycled for many runs in the process without greatly abating the biodiesel yield. Also, such catalysts possess noncorrosive nature, thus making the biodiesel safe to be used in engine without any damage. The exploitation of waste materials as catalysts would reduce the overall production cost of biodiesel. Calcium-based catalysts in the reviewed literature have shown promising outcomes for the future use and would make the process economical for large-scale industrial applications.     

Continuous production of biodiesel fuel from vegetable oil using supercritical methanol process

A system for continuous transesterification of vegetable oil using supercritical methanol was developed using a tube reactor. Increasing the proportion of methanol, reaction pressure and reaction temperature can enhance the production yield effectively. However, side reactions of unsaturated fatty acid methyl esters (FAME) occur when the reaction temperature is over 300 °C, which lead to much loss of material. There is also a critical value of residence time at high reaction temperature, and the production yield will decrease if the residence time surpasses this value. The optimal reaction condition under constant reaction temperature process is: 40:1 of the molar ratio of alcohol to oil, 25 min of residence time, 35 MPa and 310 °C. However, the maximum production yield can only be 77% in the optimal reaction condition of constant reaction temperature process because of the loss caused by the side reactions of unsaturated FAME at high reaction temperature. To solve this problem, we proposed a new technology: gradual heating that can effectively reduce the loss caused by the side reactions of unsaturated FAME at high reaction temperature. With the new reaction technology, the methyl esters yield can be more than 96%.     

Feasibility study of a thermally coupled reactive distillation process for biodiesel production

Biodiesel fuel represents an interesting alternative as a clean and renewable substitute of fossil fuels. A typical biodiesel production process involves the use of a catalyst, which implies high energy consumptions for the separation of the catalyst and the by-products of the reaction, including those of undesirable side reactions (such as the saponification reaction). A recently proposed process involves the use of short-chain alcohols at supercritical conditions, avoiding the use of a catalyst and the occurrence of the saponification reaction. This process requires fewer pieces of equipment than the conventional one, but its high energy requirements and the need of special materials that support the reaction conditions makes the main product, biodiesel fuel, more expensive than petroleum diesel. In this work, a modification of the supercritical process for the production of biodiesel fuel is proposed. Two alternatives are proposed. The process involves the use of either reactive distillation or thermally coupled reactive distillation. Simulations have been carried out by using the Aspen One™ process simulator to demonstrate the feasibility of such alternatives to produce biodiesel with methanol at high pressure conditions. A design method for the thermally coupled system is also proposed. Both systems have been tested and the results indicate favorable energy performance when compared to the original scheme. Furthermore, the thermally coupled system shows lower energy consumptions than the reactive distillation column.     

A new process for catalyst-free production of biodiesel using supercritical methyl acetate

Production of glycerol is unavoidable in the conventional processes for biodiesel fuel (BDF) production. In this research, therefore, we investigated conversion of rapeseed oil to fatty acid methyl esters (FAME) and triacetin (TA) by processing of supercritical methyl acetate. As a result, it was discovered that the trans-esterification reaction of triglycerides with methyl acetate can proceed without catalyst under supercritical conditions, generating FAME and triacetin. In order to study the effect of the triacetin addition to FAME, its effect was investigated on various fuel characteristics. It was, consequently, discovered that there were no adverse effects on the main fuel characteristics when the molar ratio of methyl oleate to triacetin was 3:1, corresponding to the theoretically derived mole ratio from the trans-esterification reaction of rapeseed oil with methyl acetate. Moreover, the addition of triacetin to methyl oleate improved the pour point and triacetin has high oxidation stability. Therefore, by defining BDF as a mixture of methyl oleate with triacetin, we can obtain an improved yield of 105% of BDF by the supercritical methyl acetate, in excess of the yield of the conventional process.