The structure and catalytic properties of SrTi1- xMgxO3- δ perovskite type catalysts for oxidative coupling of methane (OCM) have been studied by using X ray diffraction (XRD), X ray photoelectron spectroscopy (XPS) ...The structure and catalytic properties of SrTi1- xMgxO3- δ perovskite type catalysts for oxidative coupling of methane (OCM) have been studied by using X ray diffraction (XRD), X ray photoelectron spectroscopy (XPS) and Temperature programmed desorption (O2 TPD) methods. It has been shown that doping Mg2+ cations to the B site of SrTi1- xMgxO3- δ perovskite type catalysts results in the formation of oxygen vacancies in the lattices of oxide catalysts. With increasing the amount of Mg2+ doped in the B site of SrTi1- xMgxO3- δ , methane conversion and C2 selectivity first increase and then decrease remarkably. The SrTi1- xMgxO3- δ catalyst with x=0.1 has the highest methane conversion and C2 yield. It is suggested that the oxygen vacancies produced by Mg2+ cations doping are the sites responsible for oxygen activation, and the adsorbed oxygen species on the surface of SrTi1- xMgxO3- δ catalysts are the main active species for OCM reaction. However, the over high content of the adsorbed oxygen species on the surface results in the complete oxidation of methane. Introducing water steam into feedstock can improve the catalytic properties of SrTi1- xMgxO3- δ perovskite type catalysts for OCM reaction at lower temperature. The SrTi0.9Mg0.1O3- δ catalyst has the methane conversion of 28.0 % with C2 hydrocarbons selectivity of 36.8 % under reaction temperature of 550 ℃ .展开更多
The back-propagation algorithm used in artificial neural networks was usled to predict the boiling points of the fluorine-chlorine-substituted ethane derivatives.Using two inertia terms for adjustment of weights and a...The back-propagation algorithm used in artificial neural networks was usled to predict the boiling points of the fluorine-chlorine-substituted ethane derivatives.Using two inertia terms for adjustment of weights and automatic learning step control,the network used a short time for learning.The program was written in FORTRAN.The compiler is NDP FORTRAN.展开更多
The photoionization and photodissociation of bromoethane have been studied by using synchrotron radiation.The photoionization efficiency (PIE) curves of some fragments ions are measured.Based on these curves,the ioniz...The photoionization and photodissociation of bromoethane have been studied by using synchrotron radiation.The photoionization efficiency (PIE) curves of some fragments ions are measured.Based on these curves,the ionization potential of C 2H 5Br is determined to be 10.29eV,and the appearance potentials of C 2H 5 + ,CH 2Br +are measured to be 10.60eV,13.2eV respectively.We also have performed G2MP2 calculation on these fragments.According to experimental result and G2MP2 energy,the enthalpy of formation of ions C 2H 5 +,CH 2Br +,C 2H 5Br +,the bond energy of D 0(C 2H 5 +-Br),D 0(-Br),D 0(CH 2Br +-CH 3) have been evaluated.The most possible channels of the dissociation photoionization have been analyzed.展开更多
文摘The structure and catalytic properties of SrTi1- xMgxO3- δ perovskite type catalysts for oxidative coupling of methane (OCM) have been studied by using X ray diffraction (XRD), X ray photoelectron spectroscopy (XPS) and Temperature programmed desorption (O2 TPD) methods. It has been shown that doping Mg2+ cations to the B site of SrTi1- xMgxO3- δ perovskite type catalysts results in the formation of oxygen vacancies in the lattices of oxide catalysts. With increasing the amount of Mg2+ doped in the B site of SrTi1- xMgxO3- δ , methane conversion and C2 selectivity first increase and then decrease remarkably. The SrTi1- xMgxO3- δ catalyst with x=0.1 has the highest methane conversion and C2 yield. It is suggested that the oxygen vacancies produced by Mg2+ cations doping are the sites responsible for oxygen activation, and the adsorbed oxygen species on the surface of SrTi1- xMgxO3- δ catalysts are the main active species for OCM reaction. However, the over high content of the adsorbed oxygen species on the surface results in the complete oxidation of methane. Introducing water steam into feedstock can improve the catalytic properties of SrTi1- xMgxO3- δ perovskite type catalysts for OCM reaction at lower temperature. The SrTi0.9Mg0.1O3- δ catalyst has the methane conversion of 28.0 % with C2 hydrocarbons selectivity of 36.8 % under reaction temperature of 550 ℃ .
文摘The back-propagation algorithm used in artificial neural networks was usled to predict the boiling points of the fluorine-chlorine-substituted ethane derivatives.Using two inertia terms for adjustment of weights and automatic learning step control,the network used a short time for learning.The program was written in FORTRAN.The compiler is NDP FORTRAN.
文摘The photoionization and photodissociation of bromoethane have been studied by using synchrotron radiation.The photoionization efficiency (PIE) curves of some fragments ions are measured.Based on these curves,the ionization potential of C 2H 5Br is determined to be 10.29eV,and the appearance potentials of C 2H 5 + ,CH 2Br +are measured to be 10.60eV,13.2eV respectively.We also have performed G2MP2 calculation on these fragments.According to experimental result and G2MP2 energy,the enthalpy of formation of ions C 2H 5 +,CH 2Br +,C 2H 5Br +,the bond energy of D 0(C 2H 5 +-Br),D 0(-Br),D 0(CH 2Br +-CH 3) have been evaluated.The most possible channels of the dissociation photoionization have been analyzed.
