The mathematical model for the thermokinetics of irreversible consecutive first order reactions has been suggested,which was used for the calculation of rate constants and molar enthalpies of the two consecutive steps...The mathematical model for the thermokinetics of irreversible consecutive first order reactions has been suggested,which was used for the calculation of rate constants and molar enthalpies of the two consecutive steps.And its validity has been verified by the ex- perimental results.展开更多
Biodiesel is a renewable fuel that can be made from vegetable oil and waste restaurant greases by catalysed transesterification reactions. Over 5 billion gallons of biodiesel was produced in 2010. The European Union a...Biodiesel is a renewable fuel that can be made from vegetable oil and waste restaurant greases by catalysed transesterification reactions. Over 5 billion gallons of biodiesel was produced in 2010. The European Union and United States are seeing the sigmoidal portion of the growth curve in biodiesel production. Economic analysis such as profitability and annualized worth (AW) of a biodiesel plant in Taiwan is presented. With the revenue from glycerine byproduct recovery and with lower raw material costs, biodiesel may be profitable especially during days of higher gasoline prices. Multiple reactions of the consecutive-competive type may be used to model the methonolysis of trigylcerides. The reaction rate constant ratios and residence time in the reactor are important parameters in determining higher selectivity of FAME, fatty acid methyl ester product yield over glycerol by-product production. Illustrations of higher FAME yield, higher glycerol yield and cross-over from FAME to glycerol are shown for some values of reaction rate constant ratios and reaction scheme from triglycerides to diglycerides, monoglycerides and glycerol along with formation of FAME in each step by addition of methanol and catalyst is shown. Product distribution curves are presented in Figures 2-5 for different values or reaction rate constant ratios.展开更多
Hydrogenation of benzaldehyde is a typical consecutive reaction, since the intermediate benzyl alcohol is apt to be further hydrogenated. Here we demonstrate that the selectivity of benzyl alcohol can be tuned via fun...Hydrogenation of benzaldehyde is a typical consecutive reaction, since the intermediate benzyl alcohol is apt to be further hydrogenated. Here we demonstrate that the selectivity of benzyl alcohol can be tuned via functionalization of carbon nanotubes （CNTs）, which are used as the support of Pd. With the original CNTs, the selectivity of benzyl alcohol is 88% at a 100% conversion of benzaldehyde. With introduction of oxygen-containing groups onto CNTs, it drops to 27%. In contrast, doping CNTs with N atoms, the selectivity reaches 96% under the same reaction conditions. The kinetic study shows that hydrogenation of benzyl alcohol is significantly suppressed, which can be attributed to weakened adsorption of benzyl alcohol. This is most likely related to the modified electronic structure of Pd species via interaction with functionalized CNTs, as shown by XPS characterization.展开更多
We propose a kind of second-order stabilized Crank-Nicolson schemewhich can be applied to three types of Cahn-Hilliard model with dynamic boundary conditions.We give the corresponding proof of stability and convergenc...We propose a kind of second-order stabilized Crank-Nicolson schemewhich can be applied to three types of Cahn-Hilliard model with dynamic boundary conditions.We give the corresponding proof of stability and convergence theoretically which takes the reaction rate dependent dynamic boundary conditions as an example.We verify the effectiveness and universality of our proposed scheme by conducting some typical numerical simulations and comparing with the literature works.It’s found that second-order scheme takes much less CPU time than the first-order scheme to reach the same final time.展开更多
The consecutive reaction of bis [2,2,2-trifluoroethyl ] phosphite and its application to the one-pot synthesis of 3-cyano-β,γ-un-saturated nitriles with exclusive or predominant E-selectivity (E:Z = 100-85:0-15) and...The consecutive reaction of bis [2,2,2-trifluoroethyl ] phosphite and its application to the one-pot synthesis of 3-cyano-β,γ-un-saturated nitriles with exclusive or predominant E-selectivity (E:Z = 100-85:0-15) and excellent yields (94%-99%) are described.展开更多
利用强吸电子基团使自由电子离域以稳定自由基的方法,通过2,3-二氰基氢醌及其二卤衍生物(DDXQH_2,X=H、Cl、Br or Ⅰ)的漆酶催化氧化,建立了一条在静止条件下用漆酶/O_2体系获取高"稳态"浓度(>20μmol)半醌自由基阴离子的...利用强吸电子基团使自由电子离域以稳定自由基的方法,通过2,3-二氰基氢醌及其二卤衍生物(DDXQH_2,X=H、Cl、Br or Ⅰ)的漆酶催化氧化,建立了一条在静止条件下用漆酶/O_2体系获取高"稳态"浓度(>20μmol)半醌自由基阴离子的有效途径。含二卤的2,3-二氰基氢醌底物产生的半醌自由基阴离子能以离子对形式被乙酸乙酯萃取。研究表明,在半醌自由基的酶法研究中,漆酶/O_2体系有可能成为一个更有效的酶模型。实验证明,漆酶对底物的催化氧化过程具有鲜明的连串反应特征。展开更多
文摘The mathematical model for the thermokinetics of irreversible consecutive first order reactions has been suggested,which was used for the calculation of rate constants and molar enthalpies of the two consecutive steps.And its validity has been verified by the ex- perimental results.
文摘Biodiesel is a renewable fuel that can be made from vegetable oil and waste restaurant greases by catalysed transesterification reactions. Over 5 billion gallons of biodiesel was produced in 2010. The European Union and United States are seeing the sigmoidal portion of the growth curve in biodiesel production. Economic analysis such as profitability and annualized worth (AW) of a biodiesel plant in Taiwan is presented. With the revenue from glycerine byproduct recovery and with lower raw material costs, biodiesel may be profitable especially during days of higher gasoline prices. Multiple reactions of the consecutive-competive type may be used to model the methonolysis of trigylcerides. The reaction rate constant ratios and residence time in the reactor are important parameters in determining higher selectivity of FAME, fatty acid methyl ester product yield over glycerol by-product production. Illustrations of higher FAME yield, higher glycerol yield and cross-over from FAME to glycerol are shown for some values of reaction rate constant ratios and reaction scheme from triglycerides to diglycerides, monoglycerides and glycerol along with formation of FAME in each step by addition of methanol and catalyst is shown. Product distribution curves are presented in Figures 2-5 for different values or reaction rate constant ratios.
基金supported by the National Science Foundation of China (No. 21006129,11079005 and 21033009)the Ministry of Science and Technology of China (No. 2011CBA00503)
文摘Hydrogenation of benzaldehyde is a typical consecutive reaction, since the intermediate benzyl alcohol is apt to be further hydrogenated. Here we demonstrate that the selectivity of benzyl alcohol can be tuned via functionalization of carbon nanotubes （CNTs）, which are used as the support of Pd. With the original CNTs, the selectivity of benzyl alcohol is 88% at a 100% conversion of benzaldehyde. With introduction of oxygen-containing groups onto CNTs, it drops to 27%. In contrast, doping CNTs with N atoms, the selectivity reaches 96% under the same reaction conditions. The kinetic study shows that hydrogenation of benzyl alcohol is significantly suppressed, which can be attributed to weakened adsorption of benzyl alcohol. This is most likely related to the modified electronic structure of Pd species via interaction with functionalized CNTs, as shown by XPS characterization.
基金partially supported by the NSFC Nos.11871105 and 11231003partially supported by the NSFC No.12201050China Postdoctoral Science Foundation grant No.2022M710425.
文摘We propose a kind of second-order stabilized Crank-Nicolson schemewhich can be applied to three types of Cahn-Hilliard model with dynamic boundary conditions.We give the corresponding proof of stability and convergence theoretically which takes the reaction rate dependent dynamic boundary conditions as an example.We verify the effectiveness and universality of our proposed scheme by conducting some typical numerical simulations and comparing with the literature works.It’s found that second-order scheme takes much less CPU time than the first-order scheme to reach the same final time.
基金Project supported by the National Natural Science Foundation of China(No.29972046)and Chinese Academy of Sciences.
文摘The consecutive reaction of bis [2,2,2-trifluoroethyl ] phosphite and its application to the one-pot synthesis of 3-cyano-β,γ-un-saturated nitriles with exclusive or predominant E-selectivity (E:Z = 100-85:0-15) and excellent yields (94%-99%) are described.
文摘利用强吸电子基团使自由电子离域以稳定自由基的方法,通过2,3-二氰基氢醌及其二卤衍生物(DDXQH_2,X=H、Cl、Br or Ⅰ)的漆酶催化氧化,建立了一条在静止条件下用漆酶/O_2体系获取高"稳态"浓度(>20μmol)半醌自由基阴离子的有效途径。含二卤的2,3-二氰基氢醌底物产生的半醌自由基阴离子能以离子对形式被乙酸乙酯萃取。研究表明,在半醌自由基的酶法研究中,漆酶/O_2体系有可能成为一个更有效的酶模型。实验证明,漆酶对底物的催化氧化过程具有鲜明的连串反应特征。
