In a stainless steel autoclave,the synthesis kinetics of dimethyl carbonate(DMC) from urea and methanol was separately investigated without catalyst and with Zn-containing catalyst.Without catalyst,for the first react...In a stainless steel autoclave,the synthesis kinetics of dimethyl carbonate(DMC) from urea and methanol was separately investigated without catalyst and with Zn-containing catalyst.Without catalyst,for the first reaction of DMC synthesis(the reaction of urea with methanol to methyl carbamate(MC)),the reaction kinetics can be described as the first order with respect to the concentrations of both methanol and urea.For the second reaction of DMC synthesis(the reaction of MC with methanol to DMC),the results exhibit characteristics of zero-order reaction.For Zn-containing catalyst,the first reaction is neglected in the kinetics model since its rate is much faster than the second reaction.The macro-kinetic parameters of the second reaction are obtained by fitting the experimental data to a pseudo-homogenous model,in which a side reaction in forming process of DMC is incorporated since it decreases the yield of DMC drastically at high temperature.The activation energy of the reaction from MC to DMC is 104 kJ/mol while that of the side reaction of DMC is 135 kJ/mol.The highest yield of DMC is 23%.展开更多
基于全生命周期法(LCA)对CO_2-DMC(碳酸二甲酯)产业链碳足迹进行了分析,分别以常规反应塔工艺、膜反应塔工艺和反应精馏塔工艺为对象,考察了各工艺在不同能源供应情景下产业链的碳足迹情况,对原料的获取、原料的运输、燃料的使用、燃料...基于全生命周期法(LCA)对CO_2-DMC(碳酸二甲酯)产业链碳足迹进行了分析,分别以常规反应塔工艺、膜反应塔工艺和反应精馏塔工艺为对象,考察了各工艺在不同能源供应情景下产业链的碳足迹情况,对原料的获取、原料的运输、燃料的使用、燃料的运输以及产品的配送等环节进行了碳足迹分析。结果表明:3种工艺中反应精馏塔工艺能耗、碳足迹最小,常规反应塔工艺最大;以渣油为燃料常规反应塔工艺单位产品碳足迹最大,碳足迹为1.67 t CO_2/t DMC,以天然气为燃料的反应精馏塔工艺碳足迹最小,单位产品碳足迹为0.70 t CO_2/t DMC;燃料消耗碳足迹在总碳足迹中占比最大,其次为原料上游排放。展开更多
V2O5- SiO2(VSiO) supported Cu- Ni- K2O catalysts for the synthesis of dimethyl carbonate were prepared using isovolumic impregnation. Based on TPR,TPD, IR and micro- reactor techniques, the effect of K2O on the adso...V2O5- SiO2(VSiO) supported Cu- Ni- K2O catalysts for the synthesis of dimethyl carbonate were prepared using isovolumic impregnation. Based on TPR,TPD, IR and micro- reactor techniques, the effect of K2O on the adsorption and reaction of CO2 and CH3OH on the catalyst were characterized. The results show that addition of K2O exerts obvious influence on the charge distribution of the active sites on Cu- Ni/VSiO catalyst,increases the intensities of CO2 horizontal adsorption state, while that of the dissociation state of methanol descends. When the ratio of K is above 15% , K2CO3 is formed on the catalyst. Moreover,the main reaction products of CO2 and CH3OH on Cu- Ni- K2O/VSiO catalyst are still DMC, H2O, CO and CH2O,and with the addition of K2O, the conversion of reactants rise, but the selectivity of by- products decreases.展开更多
基金Project(2010ZC034) supported by the Science Foundation of Yunnan Province,ChinaProject(20105314120005) supported by the Research Fund for Doctor Program of Higher Education of China+2 种基金Project(11-12-609) supported by the Open Foundation of State Key Laboratory of Coal Conversion,ChinaProject(KKJD201051012) supported by the Scientific Research Fund of Yunnan Provincial Education Department,ChinaProject(2009-096) supported by the Analysis and Measure Foundation of Kunming University of Scienceand Technology,China
文摘In a stainless steel autoclave,the synthesis kinetics of dimethyl carbonate(DMC) from urea and methanol was separately investigated without catalyst and with Zn-containing catalyst.Without catalyst,for the first reaction of DMC synthesis(the reaction of urea with methanol to methyl carbamate(MC)),the reaction kinetics can be described as the first order with respect to the concentrations of both methanol and urea.For the second reaction of DMC synthesis(the reaction of MC with methanol to DMC),the results exhibit characteristics of zero-order reaction.For Zn-containing catalyst,the first reaction is neglected in the kinetics model since its rate is much faster than the second reaction.The macro-kinetic parameters of the second reaction are obtained by fitting the experimental data to a pseudo-homogenous model,in which a side reaction in forming process of DMC is incorporated since it decreases the yield of DMC drastically at high temperature.The activation energy of the reaction from MC to DMC is 104 kJ/mol while that of the side reaction of DMC is 135 kJ/mol.The highest yield of DMC is 23%.
文摘基于全生命周期法(LCA)对CO_2-DMC(碳酸二甲酯)产业链碳足迹进行了分析,分别以常规反应塔工艺、膜反应塔工艺和反应精馏塔工艺为对象,考察了各工艺在不同能源供应情景下产业链的碳足迹情况,对原料的获取、原料的运输、燃料的使用、燃料的运输以及产品的配送等环节进行了碳足迹分析。结果表明:3种工艺中反应精馏塔工艺能耗、碳足迹最小,常规反应塔工艺最大;以渣油为燃料常规反应塔工艺单位产品碳足迹最大,碳足迹为1.67 t CO_2/t DMC,以天然气为燃料的反应精馏塔工艺碳足迹最小,单位产品碳足迹为0.70 t CO_2/t DMC;燃料消耗碳足迹在总碳足迹中占比最大,其次为原料上游排放。
文摘V2O5- SiO2(VSiO) supported Cu- Ni- K2O catalysts for the synthesis of dimethyl carbonate were prepared using isovolumic impregnation. Based on TPR,TPD, IR and micro- reactor techniques, the effect of K2O on the adsorption and reaction of CO2 and CH3OH on the catalyst were characterized. The results show that addition of K2O exerts obvious influence on the charge distribution of the active sites on Cu- Ni/VSiO catalyst,increases the intensities of CO2 horizontal adsorption state, while that of the dissociation state of methanol descends. When the ratio of K is above 15% , K2CO3 is formed on the catalyst. Moreover,the main reaction products of CO2 and CH3OH on Cu- Ni- K2O/VSiO catalyst are still DMC, H2O, CO and CH2O,and with the addition of K2O, the conversion of reactants rise, but the selectivity of by- products decreases.