In this paper,the highly efficient ZnAlLa layered double oxide(ZnAlLa-LDO)catalyst was evaluated and used in methyl carbamate(MC)alcoholysis synthesis of dimethyl carbonate.Under optimal conditions,the MC conversion w...In this paper,the highly efficient ZnAlLa layered double oxide(ZnAlLa-LDO)catalyst was evaluated and used in methyl carbamate(MC)alcoholysis synthesis of dimethyl carbonate.Under optimal conditions,the MC conversion was 33.5% and the dimethyl carbonate(DMC)selectivity was up to 92,4% at 443 K and in 9 h.The prepared catalysts were well characterized to investigate the effect on the catalytic performance and reaction catalysis mechanism.The experimental results show that the addition of La adjusted the structure and chemical properties of ZnAl composite oxide and that the synergistic effect among Zn,Al and La play a key role in adjusting the acid-base properties and stability of the catalyst,which definitely improved the DMC selectivity and catalytic stability.Based on the proposed reaction mechanism,two kinetic models of the catalytic reaction were established and modified:LangmuirHinshelwood and power-rate law kinetic model.The good agreement between kinetic models and experimental data showed that the power-rate law kinetic model based on the elementary reactions is a suitable model for providing a theoretical basis.The pre-exponential factor and activation energy of the main reaction are 5.77×10^(7)and 77.60 kJ·mol^(-1),respectively.展开更多
With high surface area,open porosity and high efficiency,a catalyst was prepared and firstly employed in electrocatalytic reduction of CO2 and electrosynthesis of dimethyl carbonate(DMC).The electrochemical property...With high surface area,open porosity and high efficiency,a catalyst was prepared and firstly employed in electrocatalytic reduction of CO2 and electrosynthesis of dimethyl carbonate(DMC).The electrochemical property for electrocatalytic reduction of CO2 in ionic liquid was studied by cyclic voltammogram(CV).The effects of various reaction variables like temperature,working potential and cathode materials on the electrocatalytic performance were also investigated.80%yield of DMC was obtained under the optimal reaction conditions.展开更多
A quaternary ammonium salt covalently linked to chitosan was first used as a catalyst for dimethyl carbonate (DMC) synthesis by the transesterification of propylene carbonate (PC) with methanol. The effects of var...A quaternary ammonium salt covalently linked to chitosan was first used as a catalyst for dimethyl carbonate (DMC) synthesis by the transesterification of propylene carbonate (PC) with methanol. The effects of various reaction variables like reaction time, temperature and pressure on the catalytic performance were also investigated. 54% DMC yield and 71% PC conversion were obtained under the optimal reaction conditions. Notably, the catalyst was able to be reused with retention of high catalytic activity and selectivity. Consequently, the process presented here has great potential for industrial application due to its advantages such as stability, easy preparation from renewable biopolymer, and simple separation from products.展开更多
Palladium containing EMT zeolite catalyst(Pd/EMT) was prepared and used for the indirect oxidative carbonylation of methanol to dimethyl carbonate(DMC).The EMT zeolite was employed as a new catalyst support and compar...Palladium containing EMT zeolite catalyst(Pd/EMT) was prepared and used for the indirect oxidative carbonylation of methanol to dimethyl carbonate(DMC).The EMT zeolite was employed as a new catalyst support and compared with the conventional Pd containing FAU zeolite catalyst(Pd/FAU).The Pd/EMT in contrast to the Pd/FAU catalyst exhibited high intrinsic activity with the turnover frequency of 0.25 s^(-1) vs.0.11 s^(-1).The Pd/EMT catalyst showed high CO conversion of 82% and DMC selectivity of 79%,that maintained for at least 130 h,while the activity of the Pd/FAU catalyst rapidly deteriorated within 12 h.The enhanced interactions between Pd and EMT zeolite inhibited the sintering of palladium clusters and maintained the Pd2+ active sites in the Pd/EMT catalyst.The stabilization of the mono-dispersed Pd clusters within the EMT zeolite is paramount to the excellent performance of the catalyst for the indirect oxidative carbonylation of methanol to DMC.展开更多
The activities of dimethyl carbonate and dimethyl sulfate as a methylation reagent were studied by density-functional theory (DFT). B3LYP/6-31G(d, p) methods were used to optimize the structures of dimethyl carbonate ...The activities of dimethyl carbonate and dimethyl sulfate as a methylation reagent were studied by density-functional theory (DFT). B3LYP/6-31G(d, p) methods were used to optimize the structures of dimethyl carbonate and dimethyl sulfate and calculate theirs charge densities. Dimethyl sulfate is easier than dimethyl carbonate to react with a nucleophilic reagent. In dimethyl sulfate, the alkoxy carbons are the only reactive atomic nucleus because of steric hindrance. A nucleophilic reagent is more likely to react with carbonyl carbons than alkoxy carbons of dimethyl carbonate;in the presence of a Lewis acid, the phenyl nucleophilic reagent reacts with the Lewis acid first. Lewis acid increases the negative charge density of a nucleophilic reagent in polar solvent, and also incurs an accretion of steric hindrance. Polar solvent avails to ionize dimethyl carbonate and thus enables the reaction of methylation. The frequencies of transition state calculated by Gaussion 03 confirm the inferred reaction mechanism. The harvest rates of 4-methoxyphenol in the experiments of methylation reactions of hydroquinone with respectively dimethyl carbonate and dimethyl sulfate support the foregoing theortical conclusions.展开更多
The one-pot synthesis of dimethyl carbonate(DMC) with co-production of propy-lene carbonate(PC) and propylene glycol(PG) from propylene oxide( PO), carbon dioxide and methanol as the starting materials was inv...The one-pot synthesis of dimethyl carbonate(DMC) with co-production of propy-lene carbonate(PC) and propylene glycol(PG) from propylene oxide( PO), carbon dioxide and methanol as the starting materials was investigated. The catalyst adopted here was a mixture of tetrabutyl ammonium bromide and sodium methoxide. It was found that un- der the reaction conditions of t = 150 ℃, p =3-4 MPa and 2 h, the PO conversion could reach 100%, the DMC, PC and the PG selectivities were 49. 7%, 42. 7% and 49. 8%, respectively, and the selectivity of by-products was below 10%.展开更多
Critical temperatures and pressures of nominal reacting mixture in synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide (quaternary mixture of carbon dioxide + methanol + water + DMC) were mea...Critical temperatures and pressures of nominal reacting mixture in synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide (quaternary mixture of carbon dioxide + methanol + water + DMC) were measured using a high-pressure view cell. The results suggested that the critical properties of the reacting mixture depended on the reaction extent as well as its initial composition (initial ratio of carbon dioxide to methanol). Such information is essential for determining the reaction conditions when one intends to carry out the synthesis of DMC with CO2 and methanol under supercritical conditions.展开更多
A novel direct method for preparation of dimethyl carbonate and poly(ethylene terephthalate) from ethylene carbonate and dimethyl terephthalate has been demonstrated in the presence of metal acetate catalysts, lithi...A novel direct method for preparation of dimethyl carbonate and poly(ethylene terephthalate) from ethylene carbonate and dimethyl terephthalate has been demonstrated in the presence of metal acetate catalysts, lithium acetate dihydrate showed highest catalytic activity with 47.9% yield of dimethyl carbonate. This method was a green chemical process.展开更多
In order to prevent or counteract shading,plants enact a complex set of growth and developmental adaptations when they sense a change in light quality caused by other plants in their vicinity.This shade avoidance resp...In order to prevent or counteract shading,plants enact a complex set of growth and developmental adaptations when they sense a change in light quality caused by other plants in their vicinity.This shade avoidance response(SAR)typically includes increased stem elongation at the expense of plant fitness and yield,making it an undesirable trait in an agricultural context.Manipulating the molecular factors involved in SAR can potentially improve productivity by increasing tolerance to higher planting density.However,most of the investigations of the molecular mechanism of SAR have been carried out in Arabidopsis thaliana,and it is presently unclear in how far results of these investigations apply to crop plants.In this review,current data on SAR in crop plants,especially from members of the Solanaceae and Poaceae families,are integrated with data from Arabidopsis,in order to identify the most promising targets for biotechnological approaches.Phytochromes,which detect the change in light caused by neighboring plants,and early signaling components can be targeted to increase plant productivity.However,they control various photomorphogenic processes not necessarily related to shade avoidance.Transcription factors involved in SAR signaling could be better targets to specifically enhance or suppress SAR.Knowledge integration from Arabidopsis and crop plants also indicates factors that could facilitate the control of specific aspects of SAR.Candidates are provided for the regulation of plant architecture,flowering induction and carbohydrate allocation.Yet to-be-elucidated factors that control SAR-dependent changes in biotic resistance and cell wall composition are pointed out.This review also includes an analysis of publicly available gene expression data for maize to augment the sparse molecular data available for this important species.展开更多
The synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide using potassium hydroxide as catalyst in the presence of CH3I and the effect of ionic liquid on the reaction were investigated. The results ...The synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide using potassium hydroxide as catalyst in the presence of CH3I and the effect of ionic liquid on the reaction were investigated. The results showed that KOH is an effective catalyst; the high selectivity and raised yield of DMC formation under mild conditions were achieved. However, the addition of the ionic liquid, l-ethyl-3-methylimidazolium bromide (emimBr), can evidently accelerate the conversion of methanol and yield of the product.展开更多
Much attention has been paid for the synthesis of dimethyl carbonate(DMC) by urea indirect alcoholysis method, which had not been actually industrialized by now. The rigorous full process model was then necessary to o...Much attention has been paid for the synthesis of dimethyl carbonate(DMC) by urea indirect alcoholysis method, which had not been actually industrialized by now. The rigorous full process model was then necessary to optimize the process with heat integration. In this paper, a full process was designed and optimized for the DMC synthesis by urea indirect alcoholysis method based on Aspen Plus software.The technological analysis was developed to find how the process was influenced by the three main recycled materials of methanol, 1,2-propylene glycol(PG) and mixture of DMC–methanol. Simultaneously,the thermal optimization was taken into account for energy saving and the optimized process was proposed with heat integration. Moreover, the economic evaluation was implemented for the optimized process with total annualized cost(TAC) and cost of product(COP) according to the plant investment and operations. It was found that the 11.6% decrease in TAC was obtained for the optimized process compared to the original designed process. The COP analysis showed that the process was economically efficient for the production of DMC from urea and methanol.展开更多
Carbamates are important intermediates in the syntheses of pesticides, herbicides, drugs, polyurethane-based polymers, and other fine and commodity chemicals.
The gas-phase synthesis of dimethyl carbonate (DMC) from methanol, carbon monoxide and oXygen has here Studied in a flow system at atomspheric Pressure. A series of Catalyst used in this reaCtion have been prepared an...The gas-phase synthesis of dimethyl carbonate (DMC) from methanol, carbon monoxide and oXygen has here Studied in a flow system at atomspheric Pressure. A series of Catalyst used in this reaCtion have been prepared and evaluated. The influence of trivared carbon supporters, alkaline metal Promoters and operation conditions on DMC opthesis reaction has been discussed. Under the conditions of 130℃, CO/O2=1 .96, SV=3340h-1, the space-time yield (STY) of DMC over PdCl2-CuCl2-CH3COOK/ac. catalyst is 217g/l-cat h,which is higher than what is published in the literatUre so far.展开更多
Over the past few years, dimethyl carbonate (DMC) has been proven to be an efficient methylating, methoxylating, and methoxycarbonylating agent in organic syntheses, in which DMC is used to replace the toxic methyl ...Over the past few years, dimethyl carbonate (DMC) has been proven to be an efficient methylating, methoxylating, and methoxycarbonylating agent in organic syntheses, in which DMC is used to replace the toxic methyl halides, dimethyl sulfate or carbon monoxide, and so forth. Furthermore, DMC has been used in the syntheses of polycarbonates and polyurethane to develop the nonphosgene routes Therefore, DMC has become one of the most important compounds in the development of green synthetic chemistry.展开更多
The reaction between ethylene carbonate and dimethyl terephthalate was carried out for the simultaneous synthesis of dimethyl carbonate and poly(ethylene terephthalate), This reaction is an excellent chemical proces...The reaction between ethylene carbonate and dimethyl terephthalate was carried out for the simultaneous synthesis of dimethyl carbonate and poly(ethylene terephthalate), This reaction is an excellent chemical process that is environmentally friendly and produces no poisonous substance. The metal acetate catalysts used for this reaction are discussed in detail. Lithium acetate dihydrate was found to be a novel and efficient catalyst for this reaction. Compared with other metal acetates, lithium acetate dihydrate can attain a maximum catalytic activity at a lower concentration. When the reaction was carried out under the following conditions: the reaction temperature from 230 to 250 ℃, molar ratio of ethylene carbonate(EC) to dimethyl terephthalate(DMT) 3: 1, reaction time 3 h, and a catalyst amount of 0. 4% (molar fraction to DMT), the yield of dimethyl carbonate(DMC) was 79. 1%.展开更多
A facile synthesis of N-methyl-N-aryl carbamates from aromatic amines and dimethyl carbonate (DMC) has been achieved with high yields in the presence of potassium carbonate (K2CO3)and tetrabutylammonium bromide (Bu4NB...A facile synthesis of N-methyl-N-aryl carbamates from aromatic amines and dimethyl carbonate (DMC) has been achieved with high yields in the presence of potassium carbonate (K2CO3)and tetrabutylammonium bromide (Bu4NBr) under solvent-free conditions.展开更多
In this paper, a low-cost activated carbon(AC) was prepared from deactivated resin catalyst(DRC) for methyl tert-butyl ether(MTBE) synthesis through carbonization and subsequent steam activation treatment. The activat...In this paper, a low-cost activated carbon(AC) was prepared from deactivated resin catalyst(DRC) for methyl tert-butyl ether(MTBE) synthesis through carbonization and subsequent steam activation treatment. The activated carbon was characterized in detail. After loading various transition metals, including Cu^(2+), Ag+, Co^(2+), Ni^(2+), Zn^(2+), and Fe^(3+) via the ultrasonic-assisted impregnation method, a series of metal-loaded adsorbents(xM-AC) were obtained and their dimethyl sulfide(DMS) adsorption performance was investigated in a batch system. Among these adsorbents, 15Cu-AC presented a superior DMS adsorption capacity equating to 58.986 mg/g due to the formation of S-M(σ) bonds between Cu^(2+) and sulfur atoms of DMS as confirmed by the Raman spectra and kinetic study.展开更多
Dimethyl carbonate is an environmentally benign and biodegradable chemical.Based on integration of reactive distillation and pressure-swing distillation technologies,a novel process for synthesis of dimethyl carbonate...Dimethyl carbonate is an environmentally benign and biodegradable chemical.Based on integration of reactive distillation and pressure-swing distillation technologies,a novel process for synthesis of dimethyl carbonate through transesterification with propylene carbonate and methanol has been developed by Huang et al.In this work,the optimization of this process was performed by minimizing the total TAC.The results show that the optimal design flowsheet can save energy consumption by 18.6% with the propylene carbonate conversion of 99.9%.Then,an effective plant-wide control structure for the process was developed.Dynamic simulation results demonstrate that the temperature/flow rate cascade control plus with simple temperature control can keep not only product purity but also the conversion of the reactant at their desired values in the face of the disturbance in reactant feed flow rate and feed composition.展开更多
基金The financial support from the National Natural Science Foundation of China(22178089)。
文摘In this paper,the highly efficient ZnAlLa layered double oxide(ZnAlLa-LDO)catalyst was evaluated and used in methyl carbamate(MC)alcoholysis synthesis of dimethyl carbonate.Under optimal conditions,the MC conversion was 33.5% and the dimethyl carbonate(DMC)selectivity was up to 92,4% at 443 K and in 9 h.The prepared catalysts were well characterized to investigate the effect on the catalytic performance and reaction catalysis mechanism.The experimental results show that the addition of La adjusted the structure and chemical properties of ZnAl composite oxide and that the synergistic effect among Zn,Al and La play a key role in adjusting the acid-base properties and stability of the catalyst,which definitely improved the DMC selectivity and catalytic stability.Based on the proposed reaction mechanism,two kinetic models of the catalytic reaction were established and modified:LangmuirHinshelwood and power-rate law kinetic model.The good agreement between kinetic models and experimental data showed that the power-rate law kinetic model based on the elementary reactions is a suitable model for providing a theoretical basis.The pre-exponential factor and activation energy of the main reaction are 5.77×10^(7)and 77.60 kJ·mol^(-1),respectively.
基金the National Natural Science Foundation of China(No.20976197) for its financial support of this project
文摘With high surface area,open porosity and high efficiency,a catalyst was prepared and firstly employed in electrocatalytic reduction of CO2 and electrosynthesis of dimethyl carbonate(DMC).The electrochemical property for electrocatalytic reduction of CO2 in ionic liquid was studied by cyclic voltammogram(CV).The effects of various reaction variables like temperature,working potential and cathode materials on the electrocatalytic performance were also investigated.80%yield of DMC was obtained under the optimal reaction conditions.
文摘A quaternary ammonium salt covalently linked to chitosan was first used as a catalyst for dimethyl carbonate (DMC) synthesis by the transesterification of propylene carbonate (PC) with methanol. The effects of various reaction variables like reaction time, temperature and pressure on the catalytic performance were also investigated. 54% DMC yield and 71% PC conversion were obtained under the optimal reaction conditions. Notably, the catalyst was able to be reused with retention of high catalytic activity and selectivity. Consequently, the process presented here has great potential for industrial application due to its advantages such as stability, easy preparation from renewable biopolymer, and simple separation from products.
基金supported by the National Natural Science Foundation of China (21908246, 21975285, U1862118)China Postdoctoral Science Foundation (2017M622311)+1 种基金Fundamental Research Funds for the Central Universities (18CX02148A)the Sino-French International Laboratory (LIA) “Zeolites”。
文摘Palladium containing EMT zeolite catalyst(Pd/EMT) was prepared and used for the indirect oxidative carbonylation of methanol to dimethyl carbonate(DMC).The EMT zeolite was employed as a new catalyst support and compared with the conventional Pd containing FAU zeolite catalyst(Pd/FAU).The Pd/EMT in contrast to the Pd/FAU catalyst exhibited high intrinsic activity with the turnover frequency of 0.25 s^(-1) vs.0.11 s^(-1).The Pd/EMT catalyst showed high CO conversion of 82% and DMC selectivity of 79%,that maintained for at least 130 h,while the activity of the Pd/FAU catalyst rapidly deteriorated within 12 h.The enhanced interactions between Pd and EMT zeolite inhibited the sintering of palladium clusters and maintained the Pd2+ active sites in the Pd/EMT catalyst.The stabilization of the mono-dispersed Pd clusters within the EMT zeolite is paramount to the excellent performance of the catalyst for the indirect oxidative carbonylation of methanol to DMC.
文摘The activities of dimethyl carbonate and dimethyl sulfate as a methylation reagent were studied by density-functional theory (DFT). B3LYP/6-31G(d, p) methods were used to optimize the structures of dimethyl carbonate and dimethyl sulfate and calculate theirs charge densities. Dimethyl sulfate is easier than dimethyl carbonate to react with a nucleophilic reagent. In dimethyl sulfate, the alkoxy carbons are the only reactive atomic nucleus because of steric hindrance. A nucleophilic reagent is more likely to react with carbonyl carbons than alkoxy carbons of dimethyl carbonate;in the presence of a Lewis acid, the phenyl nucleophilic reagent reacts with the Lewis acid first. Lewis acid increases the negative charge density of a nucleophilic reagent in polar solvent, and also incurs an accretion of steric hindrance. Polar solvent avails to ionize dimethyl carbonate and thus enables the reaction of methylation. The frequencies of transition state calculated by Gaussion 03 confirm the inferred reaction mechanism. The harvest rates of 4-methoxyphenol in the experiments of methylation reactions of hydroquinone with respectively dimethyl carbonate and dimethyl sulfate support the foregoing theortical conclusions.
文摘The one-pot synthesis of dimethyl carbonate(DMC) with co-production of propy-lene carbonate(PC) and propylene glycol(PG) from propylene oxide( PO), carbon dioxide and methanol as the starting materials was investigated. The catalyst adopted here was a mixture of tetrabutyl ammonium bromide and sodium methoxide. It was found that un- der the reaction conditions of t = 150 ℃, p =3-4 MPa and 2 h, the PO conversion could reach 100%, the DMC, PC and the PG selectivities were 49. 7%, 42. 7% and 49. 8%, respectively, and the selectivity of by-products was below 10%.
基金financial support of the State Key Fundamental Research Project(2006CB202504)the National Natural Science Foundation of China(No.20473110)Natural Science Foundation of Shanxi Province.
文摘Critical temperatures and pressures of nominal reacting mixture in synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide (quaternary mixture of carbon dioxide + methanol + water + DMC) were measured using a high-pressure view cell. The results suggested that the critical properties of the reacting mixture depended on the reaction extent as well as its initial composition (initial ratio of carbon dioxide to methanol). Such information is essential for determining the reaction conditions when one intends to carry out the synthesis of DMC with CO2 and methanol under supercritical conditions.
文摘A novel direct method for preparation of dimethyl carbonate and poly(ethylene terephthalate) from ethylene carbonate and dimethyl terephthalate has been demonstrated in the presence of metal acetate catalysts, lithium acetate dihydrate showed highest catalytic activity with 47.9% yield of dimethyl carbonate. This method was a green chemical process.
基金supported by the funding provided to Dr. Johannes Liesche by Northwest A&F University, China
文摘In order to prevent or counteract shading,plants enact a complex set of growth and developmental adaptations when they sense a change in light quality caused by other plants in their vicinity.This shade avoidance response(SAR)typically includes increased stem elongation at the expense of plant fitness and yield,making it an undesirable trait in an agricultural context.Manipulating the molecular factors involved in SAR can potentially improve productivity by increasing tolerance to higher planting density.However,most of the investigations of the molecular mechanism of SAR have been carried out in Arabidopsis thaliana,and it is presently unclear in how far results of these investigations apply to crop plants.In this review,current data on SAR in crop plants,especially from members of the Solanaceae and Poaceae families,are integrated with data from Arabidopsis,in order to identify the most promising targets for biotechnological approaches.Phytochromes,which detect the change in light caused by neighboring plants,and early signaling components can be targeted to increase plant productivity.However,they control various photomorphogenic processes not necessarily related to shade avoidance.Transcription factors involved in SAR signaling could be better targets to specifically enhance or suppress SAR.Knowledge integration from Arabidopsis and crop plants also indicates factors that could facilitate the control of specific aspects of SAR.Candidates are provided for the regulation of plant architecture,flowering induction and carbohydrate allocation.Yet to-be-elucidated factors that control SAR-dependent changes in biotic resistance and cell wall composition are pointed out.This review also includes an analysis of publicly available gene expression data for maize to augment the sparse molecular data available for this important species.
文摘The synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide using potassium hydroxide as catalyst in the presence of CH3I and the effect of ionic liquid on the reaction were investigated. The results showed that KOH is an effective catalyst; the high selectivity and raised yield of DMC formation under mild conditions were achieved. However, the addition of the ionic liquid, l-ethyl-3-methylimidazolium bromide (emimBr), can evidently accelerate the conversion of methanol and yield of the product.
基金Supported by the Science Foundation for Young Scientists of Shanxi Province,China(201701D221052)Natural Science Foundation of Shanxi Province(201601D102006)the Key Science and Technology Program of Shanxi Province,China(MD2014-09,MD2014-10)
文摘Much attention has been paid for the synthesis of dimethyl carbonate(DMC) by urea indirect alcoholysis method, which had not been actually industrialized by now. The rigorous full process model was then necessary to optimize the process with heat integration. In this paper, a full process was designed and optimized for the DMC synthesis by urea indirect alcoholysis method based on Aspen Plus software.The technological analysis was developed to find how the process was influenced by the three main recycled materials of methanol, 1,2-propylene glycol(PG) and mixture of DMC–methanol. Simultaneously,the thermal optimization was taken into account for energy saving and the optimized process was proposed with heat integration. Moreover, the economic evaluation was implemented for the optimized process with total annualized cost(TAC) and cost of product(COP) according to the plant investment and operations. It was found that the 11.6% decrease in TAC was obtained for the optimized process compared to the original designed process. The COP analysis showed that the process was economically efficient for the production of DMC from urea and methanol.
文摘Carbamates are important intermediates in the syntheses of pesticides, herbicides, drugs, polyurethane-based polymers, and other fine and commodity chemicals.
文摘The gas-phase synthesis of dimethyl carbonate (DMC) from methanol, carbon monoxide and oXygen has here Studied in a flow system at atomspheric Pressure. A series of Catalyst used in this reaCtion have been prepared and evaluated. The influence of trivared carbon supporters, alkaline metal Promoters and operation conditions on DMC opthesis reaction has been discussed. Under the conditions of 130℃, CO/O2=1 .96, SV=3340h-1, the space-time yield (STY) of DMC over PdCl2-CuCl2-CH3COOK/ac. catalyst is 217g/l-cat h,which is higher than what is published in the literatUre so far.
基金Supported by the National Natural Science Foundation of China(No20473043)
文摘Over the past few years, dimethyl carbonate (DMC) has been proven to be an efficient methylating, methoxylating, and methoxycarbonylating agent in organic syntheses, in which DMC is used to replace the toxic methyl halides, dimethyl sulfate or carbon monoxide, and so forth. Furthermore, DMC has been used in the syntheses of polycarbonates and polyurethane to develop the nonphosgene routes Therefore, DMC has become one of the most important compounds in the development of green synthetic chemistry.
基金the National High Technology Research and Development Program of China(No 2003AA321010)
文摘The reaction between ethylene carbonate and dimethyl terephthalate was carried out for the simultaneous synthesis of dimethyl carbonate and poly(ethylene terephthalate), This reaction is an excellent chemical process that is environmentally friendly and produces no poisonous substance. The metal acetate catalysts used for this reaction are discussed in detail. Lithium acetate dihydrate was found to be a novel and efficient catalyst for this reaction. Compared with other metal acetates, lithium acetate dihydrate can attain a maximum catalytic activity at a lower concentration. When the reaction was carried out under the following conditions: the reaction temperature from 230 to 250 ℃, molar ratio of ethylene carbonate(EC) to dimethyl terephthalate(DMT) 3: 1, reaction time 3 h, and a catalyst amount of 0. 4% (molar fraction to DMT), the yield of dimethyl carbonate(DMC) was 79. 1%.
文摘A facile synthesis of N-methyl-N-aryl carbamates from aromatic amines and dimethyl carbonate (DMC) has been achieved with high yields in the presence of potassium carbonate (K2CO3)and tetrabutylammonium bromide (Bu4NBr) under solvent-free conditions.
基金financially supported by the National Natural Science Foundation of China (No. 21276086)
文摘In this paper, a low-cost activated carbon(AC) was prepared from deactivated resin catalyst(DRC) for methyl tert-butyl ether(MTBE) synthesis through carbonization and subsequent steam activation treatment. The activated carbon was characterized in detail. After loading various transition metals, including Cu^(2+), Ag+, Co^(2+), Ni^(2+), Zn^(2+), and Fe^(3+) via the ultrasonic-assisted impregnation method, a series of metal-loaded adsorbents(xM-AC) were obtained and their dimethyl sulfide(DMS) adsorption performance was investigated in a batch system. Among these adsorbents, 15Cu-AC presented a superior DMS adsorption capacity equating to 58.986 mg/g due to the formation of S-M(σ) bonds between Cu^(2+) and sulfur atoms of DMS as confirmed by the Raman spectra and kinetic study.
基金Supported by the National Natural Science Foundation of China(21306025,21576053)the International Science&Technology Cooperation Program of China(2013DFR90540)
文摘Dimethyl carbonate is an environmentally benign and biodegradable chemical.Based on integration of reactive distillation and pressure-swing distillation technologies,a novel process for synthesis of dimethyl carbonate through transesterification with propylene carbonate and methanol has been developed by Huang et al.In this work,the optimization of this process was performed by minimizing the total TAC.The results show that the optimal design flowsheet can save energy consumption by 18.6% with the propylene carbonate conversion of 99.9%.Then,an effective plant-wide control structure for the process was developed.Dynamic simulation results demonstrate that the temperature/flow rate cascade control plus with simple temperature control can keep not only product purity but also the conversion of the reactant at their desired values in the face of the disturbance in reactant feed flow rate and feed composition.