Molar Ratio Of Dimethyl Carbonate Research Articles

Alternative Route for Biodiesel Synthesis with Co-Production of Glycerol Carbonate

As an alternative route from the conventional alkali-catalyzed biodiesel production, the supercritical dimethyl carbonate method had been proven to successfully produce biodiesel with the co-production of glycerol carbonate in a one-step and two-step non-catalytic methods. Biodiesel or fatty acid methyl esters (FAME) obtained were high in yield, comparable with supercritical methanol method and satisfy the international standards for use as biodiesel in engines. In this paper, key parameters for the processes such as reaction temperature, pressure, time, molar ratio of dimethyl carbonate to oil, the FAME yield, thermal decomposition, degree of denaturation, tocopherol content, oxidation stability and fuel properties were discussed. The optimized condition for supercritical dimethyl carbonate method is at 300°C/20MPa/20min/42:1 molar ratio of dimethyl carbonate to oil with a satisfactory yield of FAME at 97.4wt%. The extensive approach in this study is very important to complement mathematical model for optimization in the literatures, and to ensure that only high-quality biodiesel could be produced by supercritical dimethyl carbonate method under an optimized condition.

β-Cyclodextrin-Calcium Complex Intercalated Hydrotalcites as Efficient Catalyst for Transesterification of Glycerol

β-cyclodextrin derivative intercalated MgAl-hydrotalcites (β-CD-Ca/LDH) was synthesized to convert glycerol into high value-added glycerol carbonate(GC) by transesterification of dimethyl carbonate (DMC) and glycerol in this paper. β-cyclodextrin-metal complexes and β-CD-Ca/LDH was characterized by XRD, FT-IR, SEM, XPS and nitrogen adsorption-desorption. The enrichment of organic reactants in the hydrophobic cavity of β-cyclodextrin improved the collision probability of reactants. The intercalation of β-cyclodextrin-calcium complex (β-CD-Ca) increased the pore size and basic strength of catalyst. The experiment results showed that the glycerol conversion was 93.7% and the GC yield was 91.8% catalyzed by β-CD-Ca/LDH when the molar ratio of DMC and glycerol was 3:1, the catalyst dosage was 4 wt.%, the reaction temperature was 75 °C and the reaction time was 100 min while the glycerol conversion was 49.4% and the GC yield was 48.6% catalyzed by MgAl-LDH under the same conditions.

Synthesis of Hydrotalcites from Waste Steel Slag with [Bmim]OH Intercalated for the Transesterification of Glycerol Carbonate.

Ca-Mg-Al hydrotalcites were prepared by coprecipitation from Type S95 steel slag of Shanghai Baosteel Group as supports of ionic liquid in this paper. Five basic ionic liquids [Bmim][CH3COO], [Bmim][HCOO], [Bmim]OH, [Bmim]Br and ChOH were prepared and their catalytic performance on the synthesis of glycerol carbonate by transesterification between dimethyl carbonate and glycerol was investigated. The characterization results indicated that [Bmim]OH is the best ionic liquid (IL) for the transesterification reaction of glycerol carbonate. The hydrotalcites before and after intercalation by ionic liquid were characterized by XRD, FTIR, SEM, EDS and the IL were characterized by FT-IR, 13C-NMR and basicity determination via the Hammett method. The analysis results implied that the dispersion of [Bmim]OH in hydrotalcites reduced the alkali density appropriately and facilitated the generation of glycerol carbonate. The yield of glycerol carbonate and the conversion rate of glycerol reached 95.0% and 96.1%, respectively, when the molar ratio of dimethyl carbonate and glycerol was 3:1, the catalyst dosage was 3 wt%, the reaction temperature was 75 °C and the reaction time was 120 min. The layered structure of hydrotalcites increased the stability of ionic liquid intercalated in carriers, thus the glycerol conversion and the GC yield still remained 91.9% and 90.5% in the fifth reaction cycle.

Lipase-Catalyzed Synthesis of Glycerol-Free Biodiesel from Rapeseed Oil and Dimethyl Carbonate

The enzymatic production of glycerol-free biodiesel by the transesterification of rapeseed oil was studied using lipase as catalyst. A series of co-solvents were employed in an attempt to improve reaction kinetics. The effects of the reaction conditions (molar ratio of dimethyl carbonate (DMC) and rapeseed oil, type of lipases, amount of lipases, solvent effects, reaction temperature and time) on the conversion and yield of biodiesel and glycerol carbonate (GC) were investigated. The optimal conditions for biodiesel and GC were 20% Novozym 435, 3:1 molar ratio of DMC to rapeseed oil, and with 20% [Omim][BF6] as solvent. Under these conditions, the conversions of 88.51% biodiesel and 73.87% GC have been achieved after 48 h. The biodiesel and GC conversions were eight times higher compared to the conventional solvent-free system, respectively. There was no obvious loss in the biodiesel and GC yield after Novozym 435 having been used for five recycling.

Utilization of Glycerol for Glycerol Carbonate Synthesis via Transesterfication Reaction over Bio-Char Catalyst prepared from reed plant

Biodiesel production process was attracted more attention recently due to the surplus quantity of glycerol (G) as a byproduct from the process. Glycerol Utilization must take in to consideration to fix this issue also, to ensure biodiesel industry sustainability. Highly amount of Glycerol converted to more benefit material Glycerol carbonate (GC) was one of the most allurement compound derived from glycerol by transesterification of glycerol with dimethyl carbonate (DMC). Various parameters have highly impact on transesterification was investigated like catalyst loading (1-5) %wt., molar ratio of DMC: glycerol (5:1 – 1:1), reaction time (30 - 150) min and temperature (40 – 80) ᴼC. The Optimum glycerol carbonate yield (YGC) and glycerol conversion (XG) was obtained 94.2% and 94.5% respectively at catalyst loading 5% wt., temperature 70ᴼC, DMC:G ratio 5:1 and 120 min. GC has large scale of uses such as liquid membrane in gas separation, surfactants ,detergents , blowing agent , in plastics industry, in Pharmaceutical industry and electrolytes in lithium batteries.

Efficient and simultaneous cleaner production of biodiesel and glycerol carbonate in solvent-free system via statistical optimization

A solvent-free co-production process for biodiesel and glycerol carbonate (GC) was developed based on enzyme (Novozyme 435). Glycerol obtained from transesterification reactions could be directly converted to GC. The reactions were optimized using the response surface methodology (RSM) separately. The optimal factors, which are enzyme loading, molar ratio of dimethyl carbonate to soybean oil, water content, and reaction temperature, were derived from the response optimizer. The results of optimization for biodiesel and GC production were re-analyzed by overlapping the contour plots of the factors. The following were the optima obtained: enzyme loading of 25 g/L, molar ratio of 15:1, water content of 0.082% (v/v), and reaction temperature of 59.65 °C. When the co-production of biodiesel and GC was conducted using the optima, biodiesel and GC production were achieved with conversions of 97.6% and 95.5%, respectively.

Переэтерификация подсолнечного масла в среде суб- и сверхкритического диметилкарбоната

At present, the development of environmentally friendly methods for producing biodiesel and the development of new renewable energy sources appears to be an urgent task. The present article reports on a study aimed at assessing the effect of the duration and temperature of sunflower oil processing in sub- and supercritical dimethyl carbonate media on the yield and composition of methyl esters of carboxylic acids. The experiment was carried out using a batch type autoclave in the temperature range of 150–325 °С and an oil : dimethyl carbonate molar ratio equal to 1 : 9. The chemical composition of transesterification products was studied using the GC-MS method. Under subcritical conditions in the range of 150–225 °С, no transesterification of oils practically is detected. An increase in the yield of methyl esters is observed at temperatures above 225 °С with a maximum value of 90.6 % mass identified in the supercritical region at 280 °С. When processed under subcritical conditions for 9 min, the yield of methyl esters does not exceed 80 % of the mass. Along with methyl esters, transesterification products were represented by mono- and diglycerides of fatty acids, methanol, glycerine and the products of glycerine transformations. The content of these products decreased under an increase in temperature. The transesterification product of oil under supercritical conditions is represented by the composition of methyl esters of carboxylic acids. The content of impurities is not more than 1 %. The effect of the treatment duration on the yield of methyl esters is shown to be most pronounced in the subcritical conditions of the process. Under supercritical conditions, more than 80 % of the oil triglycerides are converted to carboxylic acid methyl esters within 3–5 minutes of treatment. Based on the conducted studies, the choice of temperature conditions for the transesterification of oil in dimethyl carbonate medium was substantiated and additional information on the composition of the products was obtained. The authors declare no conflict of interests regarding the publication of this article.

Microwave-assisted transesterification of glycerol with dimethyl carbonate over sodium silicate catalyst in the sealed reaction system

Microwave-assisted transesterification of glycerol to glycerol carbonate (GC) using calcined sodium silicate (Na2SiO3) as a catalyst in the sealed reaction system was studied in this work. Effects of the parameters, including the molar ratio of dimethyl carbonate (DMC) to glycerol, the reaction temperature, the amount of the catalyst, the reaction time and, especially, the microwave-assisted reaction modes on glycerol conversion and GC yield were carefully investigated. It was found that the microwave-assisted reaction modes, namely, the temperature constant mode (TCM) and the power constant mode (PCM), greatly influenced the reaction. When the reaction was conducted in TCM, with the catalyst amount of 5 wt%, reaction temperature of 95 °C, DMC-to-glycerol molar ratio of 4:1, and reaction time of 15 min, the glycerol conversion and the GC yield reached 96.7% and 94.3%, respectively. Similar glycerol conversion and GC yield were also obtained under the condition of the catalyst amount of 1 wt%, DMC-to-glycerol molar ratio of 4:1, microwave irradiation input power of 175 W and reaction time of 50 s in PCM. The reaction in PCM showed much more advantages in reducing the amount of the catalyst and shortening the reaction time than that in TCM. Meanwhile, the transesterification of glycerol with DMC in PCM catalyzed by Na2SiO3 exhibited much higher reaction rate than that catalyzed by CaO. Moreover, in terms of the reaction in PCM, energy consumption could be reduced with the increase of the irradiation power. The investigation on the reusability of the Na2SiO3 catalyst in PCM showed that this catalyst could be reused in five reaction cycles without significant deactivation.

Efficient simultaneous production of biodiesel and glycerol carbonate via statistical optimization

Abstract The purpose of this study was to simultaneously produce biodiesel and glycerol carbonate. Glycerol carbonate is a high-value material that could be obtained from glycerol. Response surface methodology was used to perform optimization of simultaneous enzymatic production of biodiesel and glycerol carbonate. Independent factors for optimization of simultaneous enzymatic production included enzyme concentration, a molar ratio of dimethyl carbonate to soybean oil, and reaction temperature. The levels of satisfaction with the production reaction model for biodiesel and glycerol carbonate were high, 0.994 and 1, respectively. The optimum condition for simultaneous production was 116.76 g/L enzyme concentration, 9.27:1 molar ratio, and 52.56 °C reaction temperature. Under the optimum condition, biodiesel 96.3% and glycerol carbonate 99.7% were produced at the same time.

Phenomenological kinetic model of the synthesis of glycerol carbonate assisted by focused beam reflectance measurements

Abstract In this paper, the synthesis of glycerol carbonate from glycerol and dimethyl carbonate is studied. First, operating conditions and a catalyst were selected after screening of different alkali metal salts, resulting K2CO3 the most active species. Afterwards, given the low degree of miscibility between the reactants, a study of the phase change from a liquid–liquid emulsion to a monophasic sample throughout the reaction was successfully performed with the aid of a focused beam reflectance probe. This change took place at a conversion of approximately 0.30. With the findings of this study, distinct kinetic models were proposed and fitted to the experimental data obtained after the completion of a series of kinetic runs varying temperature (66–70 °C), molar ratio of dimethyl carbonate to glycerol (1.5–3) and catalyst load (0.75–1.25% w/w). A model composed of two potential equations was proposed with activation energy of 179.2 ± 3.7 kJ mol−1. The model was capable of describing the initial biphasic stage and the monophasic regime correlated best to the experimental data, with errors below 6.8%.

Glycerin-Free Synthesis of Jatropha and Pongamia Biodiesel in Supercritical Dimethyl and Diethyl Carbonate

To overcome the fear of glycerin glut formation based on biodiesel production process, the present study is aimed at investigation of glycerin-free biodiesel process under nonconventional synthesis conditions. Accordingly, glycerin-free synthesis of biodiesel from nonedible oils viz. jatropha and pongamia oils under supercritical conditions has been investigated with either dimethyl carbonate (DMC) or diethyl carbonate (DEC) as methylating agent. Typically, supercritical conditions with 40:1 molar ratio of DMC or DEC to oil at 325 °C/150 bar have been found to be adequate to achieve nearly complete conversion in 45 min. Furthermore, reaction kinetics has been investigated under supercritical conditions of DMC and DEC in the temperature range 250–350 °C at 150 bar. Estimated activation energies (Ea), are on the order of 38.0 ± 2 and 35.5 ± 2 kJ/mol for DMC and 40.4 ± 2 and 38.2 ± 2 kJ/mol for DEC, for conversion of jatropha and pongamia oils, respectively, with pseudo-first-order kinetics. The prepared bio...

Utilization of glycerol for the production of glycerol carbonate through greener route

Availability of glycerol is increased in recent years due to production of biodiesel. Glycerol carbonate, an important compound, can be manufactured using glycerol as a raw material. This work describes the synthesis of glycerol carbonate from glycerol via an enzymatic transesterification reaction using dimethyl carbonate as co-substrate and in presence as well as in absence of solvent. It has been observed that the glycerol and methanol (generated during transesterification) showed an inhibitory effect on the enzyme activity. In presence of solvent i.e. tertiary butanol, the rate of reaction is increased due to higher solubility of glycerol in it. Methanol was removed using molecular sieves. After the optimization of various parameters affecting the reaction, 94.85% conversion of glycerol was achieved with 1.5:1 molar ratio of dimethyl carbonate to glycerol and catalyst amount of 22.02% Novozym 435 at 60°C in 14h.

Synthesis of five and six‐membered cyclic glycerilic carbonates bearing exocyclic urethane functions

AbstractFive (5CGC) and six (6CGC) membered cyclic glycerilic carbonates having exocyclic urethane functions, as potential monomers for polyurethanes and polycarbonates, were prepared by two different routes: “two‐steps” and the “one‐pot” synthesis. For the “two‐steps” route, based on the consecutive aminolysis and transesterification reactions, a catalyst screening has been performed. Phosphazene showed the best catalytic activity and provided 5CGC and 6CGC in appreciable amounts whereas the other catalysts favored 5CGC formation. An increase in molar ratio of dimethyl carbonate (DMC) increased the yield and the conversion. In the “one‐pot” synthesis, where aminolysis and transesterification were simultaneous, a competition between products formation was demonstrated. In addition to the formation of mono‐hydroxyurethanes and glycerilic cyclic carbonates (5CGC and 6CGC), the fast aminolysis of 6CGC and the slower aminolysis of 5CGC was responsible for a partial di‐hydroxyurethanes production. The controlled and combined effects of catalyst and DMC excess acting as solvent and reagent allowed to selectively controlling the aminolysis and the transesterification reactions. The same reaction conditions were used for the synthesis of bicyclic carbonates. These new molecules enriched with urethane functions, provided novel and more environmentally friendly synthons for the synthesis of polyurethanes without the use of phosgene or isocyanate.

Optimization of supercritical dimethyl carbonate method for biodiesel production

Biodiesel could be produced from triglycerides and dimethyl carbonate, instead of the conventional methanol, in this non-catalytic supercritical dimethyl carbonate method. It was demonstrated that, supercritical dimethyl carbonate method successfully converted triglycerides as well as fatty acids to fatty acid methyl esters (FAME) with glycerol carbonate, a higher value by-product compared to the conventional glycerol. The FAME are high in yield, comparable with supercritical methanol method, and satisfy the international standard for use as biodiesel fuel. In this study, therefore, optimization of supercritical dimethyl carbonate method was discussed to include all important key parameters such as reaction temperature, pressure, time, molar ratio of dimethyl carbonate to oil, the FAME yield, thermal decomposition, degree of denaturation, tocopherol content, oxidation stability and fuel properties. The optimum condition for supercritical dimethyl carbonate method was determined at 300°C/20MPa/20min/42:1 molar ratio of dimethyl carbonate to oil to have satisfactory yield of FAME at 97.4wt%. Conclusively, this study showed the importance to address all those key parameters in order to produce high quality biodiesel from supercritical dimethyl carbonate method.

Effect of Copper Compounds on the Synthesis of Diphenyl Carbonate from Transesterification Catalyzed by <i>n</i>-Bu<sub>2</sub>SnO

Effect of copper compounds on the catalytic activity of n-Bu2SnO in the transesterification of dimethyl carbonate and phenol to diphenyl carbonate was investigated. The results showed that they as promoters could obviously enhance the activity of n-Bu2SnO except for Cu. The characterizations of X-ray diffraction (XRD) identified that CuO could be reduced to Cu, and Cu2O was stable. When the reaction was carried out between 150 and 180 oC, with molar ratio of n-Bu2SnO to Cu2O of 8:1, catalyst amount 0.0067, reaction time 10h, molar ratio of dimethyl carbonate to phenol of 3:1, the phenol conversion and the transesterification selectivity were 60.3% and 99.2%, respectively. In the transesterification, the acid-base synergistic effect between Cu2O as the basic promoter and n-Bu2SnO as the Lewis acid resulted in the active enhancement of n-Bu2SnO. Moreover the performance of Cu2O remained unchanged for seven times reuse.

Synthesis of glycerol carbonate by transesterification of glycerol with dimethyl carbonate over Mg/Al/Zr catalysts

Glycerol carbonate was synthesized by transesterification of glycerol with dimethyl carbonate using Mg/Al/Zr mixed oxide base catalysts. A series of Mg/Al/Zr catalysts were prepared with different molar ratios by using co-precipitation method and calcining at different temperatures. The catalysts were characterized by FT-infrared spectroscopy, X-ray diffraction and temperature-programmed desorption of CO 2. The transesterification activity depends on the Mg/Al/Zr molar ratio and the catalyst with Mg/Al/Zr molar ratio of 3:1:1 showed excellent activity. The catalyst activity depends on the pretreatment temperature, structure and basicity of the catalysts. The transesterification activity of catalysts was correlated with the structural aspects and the amount of basicity. Various parameters such as reaction temperature, catalyst concentration and molar ratio of dimethyl carbonate to glycerol were studied to optimize the reaction conditions.

Enzymatic coproduction of biodiesel and glycerol carbonate from soybean oil and dimethyl carbonate

The enzymatic coproduction of biodiesel and glycerol carbonate by the transesterification of soybean oil was studied using lipase as catalyst in organic solvent. To produce biodiesel and glycerol carbonate simultaneously, experiments were designed sequentially. Enzyme screening, the molar ratio of dimethyl carbonate (DMC) to soybean oil, reaction temperature and solvent effects were investigated. The results of enzyme screening, at 100 g/L Novozym 435 (immobilized Candida antarctica lipase B), biodiesel and glycerol carbonate showed conversions of 58.7% and 50.7%, respectively. The optimal conditions were 60 °C, 100 g/L Novozym 435, 6.0:1 molar ratio with tert-butanol as solvent: 84.9% biodiesel and 92.0% glycerol carbonate production was achieved.

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.

Kinetics of transesterification of palm oil and dimethyl carbonate for biodiesel production at the catalysis of heterogeneous base catalyst

The transesterification of palm oil with dimethyl carbonate (DMC) for preparing biodiesel has been studied in solvent-free system at the catalysis of potassium hydroxide (KOH) as heterogeneous catalyst. Fatty acid methyl esters (FAMEs) were analyzed by GC with internal standard method. The effects of reaction conditions (molar ratio of DMC and palm oil, catalyst amount and time) on FAMEs yield were investigated. The highest FAMEs yield could reach 96.2% at refluxing temperature for 8 h with molar ratio of DMC and oil 9:1 and 8.5% KOH (based on oil weight). Kinetics of the KOH-catalyzed transesterification of palm oil and DMC was researched over a temperature range of 65–75 °C. A pseudo first-order model was proposed. The activation energy ( E a) was 79.1 kJ mo1 −1 and the pre-exponential factor ( k o) was 1.26 × 10 9 min −1 from Arrhenius equation. Further, a plausible reaction mechanism for the catalytic process with DMC as acyl acceptor was proposed.

A novel preparation of methyl-β-cyclodextrin from dimethyl carbonate and β-cyclodextrin

A novel green synthesis process about methyl-β-cyclodextrin has been investigated through the reaction between β-cyclodextrin and dimethyl carbonate by anhydrous potassium carbonate as catalyst in DMF. The influence of experimental factors including the molar ratio of dimethyl carbonate to β-cyclodextrin, reaction temperature, and reaction time on the average degree of substitution of methyl-β-cyclodextrin was studied. The results show that the average degree of substitution of methyl-β-cyclodextrin can be dependent on the reaction temperature and the molar ratio of raw material primarily. The structures of methyl-β-cyclodextrin were characterized by TLC, IR, MS, 1H NMR, and 13C NMR.