Solvent‐free synthesis of glycerol carbonate and glycidol from 3‐chloro‐1,2‐propanediol and potassium (hydrogen) carbonate

BACKGROUND: An indirect solvent‐free synthetic approach for obtaining glycerol carbonate and glycidol from glycerol and CO₂ through their more reactive and easily synthesizable derivatives 3‐chloro‐1,2‐propanediol (HAL) and potassium (hydrogen) carbonate has been studied. RESULTS: The reaction is fast with source of carbonation and temperature having a strong influence on the results. A yield of 80% glycerol carbonate together with a simultaneous substantial production of glycidol (0.56 mol mol^?1 glycerol carbonate) are obtained using K₂CO₃ as the carbonation source at 80 °C, a reaction time of 30 min and a 3:1 HAL/K₂CO₃ molar ratio. A lower yield of glycerol carbonate (60%) is obtained from KHCO₃ after 50 min with the other experimental conditions remaining unchanged. In this case, glycidol formation is zero or insignificant. Glycerol is also obtained in high yields, although in much lower amounts from KHCO₃ (～0.59 mol mol^?1 glycerol carbonate independent of operating conditions) than from K₂CO₃ (0.84–1.1 mol mol^?1 glycerol carbonate, depending on experimental conditions). CONCLUSIONS: The proposed synthetic strategy overcomes the currently difficult direct reaction between glycerol and CO₂, leading to the simultaneous synthesis of two valuable chemicals: glycerol carbonate and glycidol. However, glycerol is also obtained in substantial amounts thus decreasing the overall yield of the process. Thus, methods for preventing its formation must be developed for industrial feasibility. Copyright © 2010 Society of Chemical Industry     

Combined processes of glycerol polymerization/carbonization/activation to produce efficient adsorbents for organic contaminants

BACKGROUND: Glycerol was used to produce efficient adsorbents with a high surface area for organic contaminants by a combined process based on polymerization, carbonization and activation. RESULTS: Glycerol and sulfuric acid catalyst at concentrations of 0, 0.5, 1, 2 and 5 mol% were heated to 150 °C to form polyglycerol, which was then decomposed at 580 °C and activated with CO₂ at 850 °C. The resulting activated carbons had a high specific area (1630 m²g^?1) and high adsorption capacity of methylene blue used as a model organic contaminant. This process was also used to produce a special composite adsorbent based on expanded vermiculite (EV) coated with activated carbon. These composites were produced by impregnation of EV with glycerol followed by polymerization, thermal decomposition and activation with CO₂ to produce up to 25 wt% carbon and a surface area of 835 m²g^?1. CONCLUSIONS: The carbon layer present in the EV composite/activated carbon (GVE4CA2) produces a remarkable increase in the methylene blue adsorption capacity of the expanded vermiculite and strongly decreases undesirable water absorption. Copyright © 2012 Society of Chemical Industry     

甘油法合成缩水甘油

以ZnSO4为催化剂,甘油和尿素反应合成碳酸甘油酯,分别以IR和MS对产物进行了结构表征。碳酸甘油酯在磷酸钠催化下脱掉一分子CO2得到缩水甘油。重点对碳酸甘油酯脱CO2得到缩水甘油的反应时间、反应温度、反应压力、催化剂种类及用量等因素进行了考察。并通过响应面分析法得到了适宜的反应条件为：反应时间4 h、反应温度215 ℃、反应压力2 kPa、催化剂用量2.5%（质量分数）。缩水甘油经旋转蒸发提纯,通过IR、HNMR进行了鉴定,GC测定产率可达到83.8%。     

碳酸甘油酯的合成研究及产业化进展

碳酸甘油酯是一种颇具吸引力的高附加值甘油衍生物,研究以甘油为反应底物制备高附加值的碳酸甘油酯,已成为实现生物柴油副产物甘油综合利用的有效途径之一。本文简述了包括光气法、CO氧化羰化法、酯交换法、尿素醇解法、CO ₂转化法等在内的碳酸甘油酯合成方法,总结了现有碳酸甘油酯合成的主要催化剂及催化合成反应机理,并简要介绍了我国原料甘油市场现状及国内外碳酸甘油酯合成的产业化进展。最后,从技术研发和产业化发展两个方面对碳酸甘油酯合成的未来发展进行了展望,指出一方面应在开发具有高性能催化剂的同时注重催化基础理论的研究,另一方面应在优化工艺流程、降低产品成本的同时注重下游产业应用与替代,并提出我国应推进生物柴油副产物甘油合成碳酸甘油酯的规模化生产与应用示范,加快培育具有国际竞争力的生物质能源与废弃物资源化利用产业。     

Process coupling of CO2 and glycerol comprehensive utilization based on anionic 2D nanomaterial

We developed an approach to realize the comprehensive utilization of CO₂ and glycerol by smartly design a nanocatalyst, which concerns the coupling of catalytic reactions and the separation or capture process. Specifically, MgFe-CO₃²⁻-LDHs with different thickness were fabricated by employing atmospheric CO₂ as carbon source and an atomic-level interface was constructed by introducing Pt single atoms to obtain series of Pt/MgFe-LDHs nanocatalysts. During a catalytic assessment, the CO₃²⁻ confined within interlayer was in situ converted when integrated with glycerol oxidation under irradiation. The optimal nanocatalyst exhibited a decent conversion efficiency of CO₃²⁻-CO-CH₄ and near 100% selectivity of secondary hydroxy group in glycerol. DFT calculation, isotope-labeled experiments and in situ spectrograph characterization revealed possible coupling reaction mechanism. More importantly, the nanocatalyst exhibited impressive reusability for at least six 6 runs. The developed multiple coupling process will be an alternative and promising procedure for the waste and low-valued sources synergetic utilization.     

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。     

Hydrogen production from glycerol by reforming in supercritical water over Ru/Al2O3 catalyst

Supercritical water is a promising medium for the reforming of hydrocarbons and alcohols for the production of hydrogen at high pressures in a short reaction time. Water serves both as a dense solvent as well as a reactant. In this work, hydrogen is produced from glycerol by supercritical water reforming over a Ru/Al₂O₃ catalyst with low methane and carbon monoxide formation. Experiments were conducted in a tubular fixed-bed flow reactor over a temperature range of 700–800 °C, feed concentrations up to 40 wt% glycerol, all at short reaction time of less than 5 s. Glycerol was completely gasified to hydrogen, carbon dioxide, and methane along with small amounts of carbon monoxide. At dilute feed concentrations, near-theoretical yield of 7 mol of hydrogen/mol of glycerol was obtained, which decreases with an increase in the feed concentration. Based on a kinetic model for glycerol reforming, an activation energy of 55.9 kJ/mol was observed.     

The effect of raw glycerol concentration on the production of 1,3‐propanediol by Clostridium butyricum

Raw glycerol, the main by‐product of the bio‐diesel production process, was converted to 1,3‐propanediol by Clostridium butyricum F2b. In batch cultures, 47.1 g dm^?3 of 1,3‐propanediol were produced. Continuous cultures were conducted at a constant dilution rate (= 0.04 h^?1) and various inlet glycerol concentrations with 1,3‐propanediol produced at levels up to 44.0 g dm^?3. At increasing glycerol concentrations in the inlet medium, biomass yield decreased. This decrease was attributed to the microbial metabolism being directed towards the biosynthesis of organic acids (and hence carbon losses as CO₂) instead of biochemical anabolic reactions. An autonomous analytical model was developed, and quantified the effect of inlet glycerol concentration on the production of biomass and metabolites. Indeed, high inlet substrate concentrations positively affected the biosynthesis, principally of butyric acid and to a lesser extent that of acetic acid. In contrast, at increased glycerol concentrations, the relative increase of 1,3‐propanediol production per unit of substrate consumed was lower as compared with that of acetic and, mainly, butyric acid. This could be explained by the fact that the butyric acid pathway represents an alternative and competitive one to that of 1,3‐propanediol for re‐generation of NADH₂ equivalents in the microbial cell. Copyright © 2004 Society of Chemical Industry     

磺酸功能化离子液体催化甘油与甲醇醚化反应

考察了[HSO₃-bmim]CF₃SO₃、[HSO₃-bmim]P-TSA、[HSO₃-bmim]HSO₄和[HSO₃-bmim]H₂PO₄四种磺酸功能化离子液体对甘油与甲醇醚化反应的影响。结果表明,离子液体的催化性能与其酸强度相关联,[HSO₃-bmim]CF₃SO₃离子液体的酸强度最强,其催化性能也最好。以[HSO₃-bmim]CF₃SO₃为催化剂,在w([HSO₃-bmim]CF₃SO₃)/w(甘油)=0.5:1(质量比)、n(甲醇)/n(甘油)=8:1(摩尔比)、反应温度190℃、反应时间8 h时,甘油的转化率为84.5%,单甲基甘油醚的选择性为41.4%,二甲基甘油醚和三甲基甘油醚的联合选择性为34.1%。在此基础上,提出了离子液体[HSO₃-bmim]CF₃SO₃催化甘油与甲醇醚化反应的反应机理。     

Supercritical water gasification of glycerol: Intermediates and kinetics

In this paper, the liquid products from supercritical water gasification (SCWG) of glycerol were analyzed and some intermediates were identified. A simplified reaction pathway for gases production from SCWG of glycerol was proposed. The first quantitative kinetics model for describing the gaseous products (H₂, CO, CH₄ and CO₂) of SCWG of glycerol was developed. The model comprises seven reactions to describe the typical reactions in SCWG, and the reaction rate constant of each reaction was obtained by using the nonlinear least-square fitting method. The reaction rate analysis showed that the main sources of hydrogen yield were glycerol pyrolysis and steam reforming of intermediates, while the hydrogen yield from water–gas shift reaction (WGSR) was very small. The temperature estimated by the kinetics model for completely SCWG of glycerol solution was given. In addition, the sensitivity analysis of rate constant of WGSR was done based on the model.     

CeO_2/C有序介孔材料催化甘油转化制碳酸甘油酯

采用溶剂挥发自组装法制备有序介孔CeO_2/C复合材料,利用X射线衍射仪、N_2吸附-脱附仪和透射电子显微镜对样品进行表征,考察催化甘油酯交换制备碳酸甘油脂的催化性能。结果表明,在甘油用2 mmol、碳酸二甲酯10 mmol、有序介孔CeO_2/C复合材料0.1 g、N,N-二甲基乙酰胺5 m L、反应温度140℃和反应时间3 h条件下,CeO_2/C中CeO_2质量分数为16.3%时,甘油转化率和碳酸甘油脂选择性最高,分别为76%和81.8%。     

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.     

Reforming of methanol and glycerol in supercritical water

Reforming of pure glycerol, crude glycerin, and methanol (pure and in the presence of Na₂CO₃) in supercritical water was investigated. Continuous experiments were carried out at temperatures between 450 and 650 °C, residence times between 6 and 173 s, and feed concentrations of 3-20 wt%. For methanol the gas products are mainly H₂, CO₂, and CO. The carbon-to-gas efficiency and the observed activation energy for pure methanol are higher than for methanol with Na₂CO₃. This can be explained by assuming different decomposition mechanisms for pure methanol and methanol with Na₂CO₃. For glycerol, H₂, CO, CO₂, CH₄, and higher hydrocarbons are produced. The carbon-to-gas efficiencies of crude glycerin and pure glycerol are comparable. Overall, 2 of the 3 carbon atoms present in glycerol end up in carbon oxides, while 1 carbon atom becomes C_xH_y. The overall mechanism of glycerol decomposition involves the dehydration of 1 mole of H₂O/mole glycerol. For both, methanol and glycerol at carbon-to-gas efficiencies below 70%, the gas yields (mole/mole feed) and carbon-to-gas efficiency correlate well.     

碘化铯催化二氧化碳与甘油合成甘油碳酸酯

以不同碱金属(铵)卤化物为催化剂,考察了其在二氧化碳与甘油合成甘油碳酸酯反应中的活性。采用环氧丙烷为溶剂及耦合剂,极大提高了反应的转化率。实验结果发现碘化物具有较好的催化活性。以碘化铯为催化剂,考察了反应温度、反应时间、反应压力、反应物摩尔比和催化剂用量对反应结果的影响。在最佳反应条件下(环氧丙烷0.3 mol,甘油0.1 mol,反应温度120℃,反应时间1.5 h,反应压力3.0 MPa,催化剂用量0.15 g),甘油的转化率为86.5%,甘油碳酸酯的产率为81.6%。     

Activity performance and kinetics for glycerol carbonylation with urea over Zn-Co mixed metal oxide catalyst

Efficient carbonylation of glycerol using urea with Zn-Co mixed metal oxide (MMO) catalyst has been achieved. Various methods of catalyst preparation were explored for glycerol carbonate (GC) synthesis. The optimized method of catalyst preparation was found to be co-precipitation (CP) with a Zn:Co ratio of 70:30, achieving 81% glycerol conversion with 97% GC selectivity. X-ray diffraction (XRD) studies revealed the formation of ZnO, Co₃ O₄, and spinel ZnCo₂O₄ phases. Thermal treatment given to the catalyst allows insertion of Zn cations into Co₃O₄ lattice forming ZnCo₂O₄ phase which was also evidenced in X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Herein, for the first time, reaction kinetics was studied to propose the rate equation, based on which a plausible reaction pathway is proposed involving two-site adsorption of glycerol (basic site) and urea (acidic site), which undergo carbonylation followed by cyclization into GC. A recycle study and hot filtration test have proven the reusability of the catalyst.     

Reactions of glycerol with poly(ethylene ether carbonate) polyols

Poly(ethylene ether carbonate) polyols can be modified by chemical reactions with polyglycol modifiers under conditions of elevated temperatures and reduced pressures. The modifier becomes chemically incorporated into the modified polyol and is used to control properties such as moisture sensitivity, CO₂ content, T_g, density, etc. in the resultant polyol. However, glycerol cannot be used as a modifier for poly(ethylene ether carbonate) polyols under the same conditions since it reacts with poly(ethylene ether carbonate) polyols by a transesterification reaction sequence to form glyceryl carbonate. As the temperature is increased, the glyceryl carbonate decomposes to yield glycidol and carbon dioxide. These reactions are conveniently followed by ¹³C-NMR. The preparation of glyceryl carbonate by this process has not been previously reported.     

Selective hydrogenolysis of glycerol to propylene glycol on Cu–ZnO catalysts

Hydrogenolysis of biomass-derived glycerol is an alternative route to sustainable production of propylene glycol. Cu–ZnO catalysts were prepared by coprecipitation with a range of Cu/Zn atomic ratio (0.6–2.0) and examined in glycerol hydrogenolysis to propylene glycol at 453–513 K and 4.2 MPa H₂. These catalysts possess acid and hydrogenation sites required for bifunctional glycerol reaction pathways, most likely involving glycerol dehydration to acetol and glycidol intermediates on acidic ZnO surfaces, and their subsequent hydrogenation on Cu surfaces. Glycerol hydrogenolysis conversions and selectivities depend on Cu and ZnO particle sizes. Smaller ZnO and Cu domains led to higher conversions and propylene glycol selectivities, respectively. A high propylene glycol selectivity (83.6%), with a 94.3% combined selectivity to propylene glycol and ethylene glycol (also a valuable product) was achieved at 22.5% glycerol conversion at 473 K on Cu–ZnO (Cu/Zn = 1.0) with relatively small Cu particles. Reaction temperature effects showed that optimal temperatures (e.g. 493 K) are required for high propylene glycol selectivities, probably as a result of optimized adsorption and transformation of the reaction intermediates on the catalyst surfaces. These preliminary results provide guidance for the synthesis of more efficient Cu–ZnO catalysts and for the optimization of reaction parameters for selective glycerol hydrogenolysis to produce propylene glycol.     

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.     

Synthesis of organic carbonates from alcoholysis of urea: A review

Organic carbonates are green compounds with a wide range of applications. They are widely used for the synthesis of important industrial compounds including monomers, polymers, surfactants, plasticizers, and also used as fuel additives. They can be divided into two main classes: cyclic and linear carbonates. Dimethyl carbonate (DMC) and diethyl carbonate (DEC) are the important linear carbonates. Carbonyl and alkyl groups present in DMC and DEC make them reactive and versatile for synthesizing various other important compounds. Ethylene carbonate (EC), glycerol carbonate (GC) and propylene carbonate (PC) are well-known cyclic organic carbonates. Phosgenation of alcohols was widely used for synthesis of organic carbonates; however, toxicity of raw materials restricted use of phosgenation method. A number of new non-phosgene methods including alcoholysis of urea, carbonylation of alcohols using CO₂, oxy-carbonylation of alcohols, and trans-esterfication of alcohols and carbonates have been developed for synthesizing organic carbonates. Carbonylation of alcohols is preferred as it helps in utilization and sequestration of CO₂, however, poor thermodynamics due to high stability of CO₂ is the major obstacle in its large scale commercialization. Oxy-carbonylation of alcohols offers high selectivity but presence of oxygen poisons the catalyst. Recently, alcoholysis of urea has received more attention because of its inexpensive abundant raw materials, favorable thermodynamics, and no water-alcohol azeotrope formation. Also, ammonia evolved in this synthesis route can be recycled back to urea by reacting it with CO₂. In other words, this method is a step towards utilization of CO₂ as well. This article reviews synthesis of DMC, DEC, GC, PC, and EC from urea by critically examining various catalysts used and their performances. Mechanisms have been reviewed in order to give an insight of the synthesis routes. Research challenges along with future perspectives have also been discussed.     

Synthesis of glycerol triacetate using functionalized ionic liquid as catalyst

BACKGROUND: With the development of bio‐diesel, it has become an urgent task to make full use of glycerol, which is a by‐product of the production of bio‐diesel. Glycerol triacetate (GTA) is one of the important derivatives of glycerol and can be used in many fields. Usually it is prepared industrially in the presence of mineral acidic catalysts. The shortcomings of such a process include serious environmental issues, complicated technique and no recyclability of catalyst. Recently, it was reported that many acidic functionalized ionic liquids (FILs) could be synthesized and used in esterifications with excellent catalytic performance. Hence, the esterification of glycerol with acetic acid to produce GTA was investigated using acidic FILs as catalyst. RESULTS: The results indicated that [HSO₃‐pmim][HSO₄] exhibited promising catalytic performance. Using [HSO₃‐pmim][HSO₄] as catalyst, the yield of GTA was above 95%. The catalyst was utilized ten times and the GTA yield remained above 91%. CONCLUSION: The good catalytic performance and reusability of this FIL may contribute to the development of an environmentally friendly strategy for the synthesis of GTA. Copyright © 2009 Society of Chemical Industry