Optimization of supercritical dimethyl carbonate (SCDMC) technology for the production of biodiesel and value-added glycerol carbonate

In the present study, biodiesel has been successfully produced from triglycerides and dimethyl carbonate, instead of the conventional alcohol. In this non-catalytic supercritical dimethyl carbonate (SCDMC) technology, valuable compound of glycerol carbonate is obtained as side product, rather than the undesirable glycerol. Glycerol carbonate has higher commercial value compared to glycerol and its application in industries is enormous. In this optimization study, the effects of important parameters including reaction temperature, molar ratio of dimethyl carbonate to oil and reaction time were investigated and optimized by employing response surface methodology (RSM) analysis. It was found that the mathematical model developed was statistically significant and adequate to predict the optimum yield. The optimum conditions for SCDMC process was found to be 380 °C for reaction temperature, 39:1 mol/mol of dimethyl carbonate to oil molar ratio and 30 min of reaction time to obtain 91% optimum yield of biodiesel.     

超临界制备生物柴油及副产甘油工艺研究

利用植物油和超临界甲醇制备生物柴油及副产甘油,增加了油相在其中的溶解度,提高了原料转化率和产品收率。实验考察了醇油摩尔比、压力、温度、时间等对生物柴油及副产物甘油产率的影响,结果表明:醇油摩尔比、压力、温度、时间等因素对生物柴油及甘油产率影响较为显著。通过正交实验设计得出的超临界甲醇制备生物柴油的工艺条件为醇油摩尔比30∶1,压力20 MPa,温度280℃,保温时间60 m in,生物柴油和甘油产率可分别达到89.14%和88.73%。     

Production of glycerol carbonate using crude glycerol from biodiesel production with DBU as a catalyst

The biodiesel production technology catalyzed by 1,8-diazabicycloundec-7-ene (DBU) is developed in this work. Crude glycerol containing DBU and DBU/glycerol/CO₂ (DGC) ionic compounds reacts directly with dimethyl carbonate (DMC) to produce high value-added glycerol carbonate (GC) catalyzed by DBU and DGC. The catalytic performance of DBU and DGC, as well as the kinetics of the reaction catalyzed by DBU, were investigated. The results show that DGC has a weak catalytic effect on the transesterification of glycerol and DMC. When the temperature is higher than 60℃, DGC catalyzes the reaction jointly with DBU, which is produced from the decomposition of DGC. DBU has a good catalytic effect on the reaction between glycerol and DMC, with 90% conversion of glycerol and 84% selectivity to GC under the following conditions:DMC-to-glycerol molar ratio of 3:1, 4.0% DBU (based on glycerol mass), reaction time of 60 min, and reaction temperature of 40℃. The apparent kinetics results show that the activation energies are 30.95 kJ·mol^-1 and 55.16 kJ·mol^-1 for the forward and reverse GC generation reactions, respectively, and the activation energy of the decomposition reaction of GC to glycidol (GD) is 26.58 kJ·mol^-1.     

KF/C催化甘油酯交换合成碳酸甘油酯

以三嵌段共聚物(EO-PO-EO)F127为结构导向剂,甲阶酚醛树脂为碳源,KF·2H₂O为无机前驱体,用溶剂诱导挥发自组装的方法合成KF/C复合材料。采用XRD、BET和XPS等手段对合成的材料进行结构表征,并考察KF/C在甘油与碳酸二甲酯酯交换合成碳酸甘油酯反应中的性能,结果表明,在甘油加入量为0.184 6 g、碳酸二甲酯加入量为0.900 7 g、溶剂N,N-二甲基乙酰胺为5.426 g、催化剂KF/C加入量为0.1 g、反应温度100 ℃、反应时间2 h和搅拌速率600 r·min^-1条件下,甘油转化率达98.5%,碳酸甘油酯选择性达99.8%,催化剂具有较好的循环使用性能。     

KF/MgO催化甘油和碳酸二甲酯酯交换合成甘油碳酸酯

采用浸渍法制备KF/MgCO₃前体,经高温焙烧后获得了一系列KF/MgO固体碱催化剂,用于催化碳酸二甲酯（DMC）和甘油（GL）酯交换反应合成甘油碳酸酯（GC）。系统考察了KF负载量和焙烧温度对催化剂活性的影响,并通过X射线衍射、N₂吸脱附等温线、扫描电子显微镜和哈米特酸碱滴定等一系列技术对催化剂的结构性能进行了表征。结果表明,当KF负载量为20%（质量分数）时,经550℃焙烧所获得的20%KF/MgO-550催化剂活性最高。经过反应工艺条件的优化,当催化剂与甘油的相对质量分数为2%,DMC与GL的摩尔比为3∶1,75℃条件下反应1.5h后,GC收率可以达到96.8%。当20%KF/MgO-550催化剂重复使用3次之后,GC的收率由96.8%降低到67.3%,经再生处理后20%KF/MgO-550的催化活性可以恢复并且表现出更优异的稳定性。     

Synthesis of glycerol carbonate from glycerol and dimethyl carbonate by transesterification: Catalyst screening and reaction optimization

The synthesis of glycerol carbonate from glycerol and dimethyl carbonate by transesterification is reported. Firstly, a catalyst screening has been performed by studying the influence of different basic and acid homogeneous and heterogeneous catalysts on reaction results. Catalytic activity is extremely low for acidic catalysts indicating that reaction rate is very slow. On the contrary, high conversions and yields are obtained for basic catalysts. Catalytic activity increases with catalyst basic strength. The best heterogeneous catalyst is CaO. Calcination of CaO increases dramatically its activity due to calcium hydroxide removal from its surface. A reaction optimization study has been carried out with CaO as catalyst by using a factorial design of experiments leading to operation conditions for achieving a 100% conversion and a >95% yield at 1.5 h reaction time: 95 °C, catalyst/glycerol molar ratio = 0.06 and dimethyl carbonate/glycerol molar ratio = 3.5. Carbonate glycerol can be easily isolated by filtering the catalyst out and evaporating the filtrate at vacuum. Leaching of catalyst in reaction medium was lower than 0.34%. Catalyst recycling leads to a quick decrease in both conversions and yields probably due to a combination of catalyst deactivation by CaO exposure to air between catalytic runs, and a decrease in the catalyst surface area available for reaction due to particle agglomeration.     

非光气法生产碳酸二甲酯

介绍了非光气法（酯交换法、甲醇氧化羰基化法）生产碳酸二甲酯的原理、工艺路线及研究进展，对其发展前景进行了分析和预测。     

Coupling reaction and azeotropic distillation for the synthesis of glycerol carbonate from glycerol and dimethyl carbonate

A new process, coupling reaction and azeotropic distillation was proposed for the synthesis of glycerol carbonate (GC) from glycerol (G) and dimethyl carbonate (DMC). The bench scale experimental investigation was systematically conducted for this new process. With calcium oxide (CaO) as the solid catalyst, the high yield of glycerol carbonate can be obtained at a low molar ratio of dimethyl carbonate to glycerol with the method of coupling reaction and azetropic distillation. The effect of azeotropic agents on glycerol carbonate yield was explored, and indicated that benzene was the most effective azeotropic agent. The effects of the process parameters, tower height, amount of added benzene, final temperature of tower bottom and reflux ratio were investigated. Glycerol carbonate yield can be as high as 98% under the conditions at molar ratio of dimethyl carbonate to glycerol 1:1, final temperature of tower bottom 85 °C, 1.5 mass ratio of added benzene to that in the azeotrope with methanol theoretically produced and reflux ratio 4. By continuously removing methanol from reaction system with the method of coupling reaction and azeotropic distillation, the yield of glycerol carbonate can be retained at high level using the recycled catalyst.     

Glycerol carbonate synthesis from glycerol and dimethyl carbonate using guanidine ionic liquids

A large number of surplus glycerol from the biodiesel production can be used as renewable feedstock to produce glycerol carbonate.In this paper,a series of guanidine-based ionic liquids were synthesized to catalyze the transesterification of glycerol and dimethyl carbonate.The tunable basicity and the anion-cation cooperative effect were responsible for the obtained results.The [TMG][TFE] showed the best activity turnover frequency (TOF) of 1754.0 h-1,glycerol (GL) conversion of 91.8％,glycerol carbonate (GC) selectivity of 95.5％) at 80 ℃ with 0.1 mol％ catalyst for 30 min.The reaction mechanism of the transesterification was also proposed.     

超临界甲醇法制备生物柴油

研究了超临界甲醇法制备生物柴油中温度、醇油摩尔比、反应时间和助溶剂对甲酯生成率的影响,同时研究了加入少量的KOH以降低反应的苛刻条件.在超临界甲醇反应温度350℃,醇油摩尔比为421的优化反应条件下,10min后脂肪酸甲酯的产率达到95.0%以上;300℃时加入CO2和正己烷可以提高甲基酯的转化率;在160℃的亚临界状态下、醇油摩尔比为241时,加入质量分数为0.1%的KOH,20min后脂肪酸甲酯的转化率也达到了98.5%以上.     

Comparison of polycarbonate precursors synthesized from catalytic reactions of bisphenol‐A with diphenyl carbonate,dimethyl carbonate,or carbon monoxide

Transesterification of bisphenol‐A with diphenyl carbonate or dimethyl carbonate, and direct oxidative carbonylation of bisphenol‐A were compared to obtain polycarbonate precursors for phosgene‐free polycarbonate synthesis. The melt‐transesterification of bisphenol‐A and diphenyl carbonate occurred readily to produce reactive precursors without a significant equilibrium constraint. On the other hand, the transesterification of bisphenol‐A and dimethyl carbonate showed a serious equilibrium limitation in obtaining reactive polycarbonate precursors leading to high molecular weight polymers, and coproduced a significant amount of methylated bisphenol‐A. The direct oxidative carbonylation of bisphenol‐A with CO produced diphenolic‐ended oligomers and a significant amount of by‐products, which are the least reactive in the subsequent polycondensation step of the phosgene‐free polycarbonate process. A novel method to synthesize the reactive polycarbonate precursors was proposed that employed the coupled oxidative carbonylation of both bisphenol‐A and phenol. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 937–947, 2002     

氧化羰基化合成碳酸二甲酯催化剂的研究进展

甲醇氧化羰基化是合成碳酸二甲酯的重要方法,也是重要的煤炭清洁利用途径之一,近年来获得较大发展。本文详细阐述了该工艺过程中有关催化剂的国内外研究现状及发展趋势,并根据载体的结构特征,按照分子筛载体、活性炭载体和其它载体,将铜基催化剂分为三类,综合论述了合成催化剂的制备技术,表面微观结构和特征、催化性能以及催化机理等方面的最新研究进展。通过深入分析和比较,认为分子筛和活性炭为载体制备的负载无氯铜基催化剂,不仅具有较好的催化活性和稳定性,而且避免了以前CuCl/CuCl2为活性组分催化剂中Cl离子对催化剂活性和稳定性的影响,以及对设备造成的腐蚀,具有较好的发展前景。     

蔗糖高压催化氢化裂解制甘油

概述了我国甘油工业的发展状况及世界发展趋势。介绍了蔗糖催化氢解法制备甘油的工艺条件和影响氢解反应的因素。指出根据我国实际情况开展蔗糖氢解法制备甘油的研究，将为我国甘油工业的发展探索一条新路。     

碳酸二甲酯的生产与技术经济

介绍了ＤＭＣ的用途、国内外市场需求及生产方法，对ＥＮＩ的液相氧化羰基化法和日本宇部兴产的气相氧化羰基化法进行了技术经济比较，并从工程设计角度对国内建设氧化羰基化法ＤＭＣ装置进行了经济评价。     

Microwave‐assisted synthesis of polyglycerol from glycerol carbonate

Microwave irradiation of glycerol carbonate allows formation of glycidol, which readily polymerizes to form polyglycerol under mild conditions comparatively to the classical polyetherification reaction involving high temperature and basic conditions. Analysis of the crude reactional mixture indicated the presence of low‐molecular weight oligomers constituted mainly of di, tri, and tetraglycerols with small quantities of higher molecular weights oligomers. Molecular size distribution was relatively similar to that of polyglycerols obtained under basic condition, even if these latter contained slightly higher amounts of high‐molecular weight oligomers. Structure of oligomers differs slightly according to the conditions of polymerization, and polyglycerols are obtained under microwave activation containing higher contents of cyclic isomers, whereas polyglycerols obtained under basic conditions contain more ramified isomers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

尿素醇解法合成碳酸二甲酯催化精馏工艺模拟

在AspenPlus平台上对尿素醇解法合成碳酸二甲酯反应精馏工艺进行模拟,针对反应精馏塔塔顶冷凝器结晶堵塞问题,优化了采出方式,提高了塔顶温度,以防止结晶。     

Catalytic synthesis of toluene‐2,4‐diisocyanate from dimethyl carbonate

The process for catalytic synthesis of toluene‐2,4‐diisocyanate (TDI) from dimethyl carbonate (DMC) consists of two steps. Starting from the catalytic reaction between toluene‐2,4‐diamine (TDA) and DMC, dimethyl toluene‐2,4‐dicarbamate (TDC) is formed, and then decomposed to TDI. For the first step, the yield of TDC is 53.5% at a temperature of 250 °C, over Zn(OAc)₂/α–Al₂O₃ catalyst. For the second step, the yield of TDI is 92.6% at temperatures of 250–270 °C and under pressure of 2.7 kPa, over uranyl zinc acetate catalyst, when di‐n‐octyl sebacate(DOS) is used as heat‐carrier, and a mixture of tetrahydrofuran (THF) and nitrobenzene is used as solvent. © 2001 Society of Chemical Industry     

Detailed investigation of non‐catalytic DPF regeneration

The present investigation concerns the phenomena that occur during the non‐catalytic regeneration of Diesel Particulate Filters (DPFs). The temperature evolution in the filter has been correlated to the emissions of CO, HC, NO, and NO₂ during the loading and regeneration process. The emissions were assessed over both the diesel oxidation catalyst (DOC) and the DPF, in order to characterise the chemical species evolution inside the after‐treatment line. Different regeneration temperatures, which have been found to have a strong impact on the evolution of the soot oxidation rate, have been assessed. Finally, the particulate emissions during regeneration have been measured on a number and size basis.