The surface disproportionation reaction mechanism of aluminum subchloride on the aluminum （100） surfaces has been investigated by the plane-wave density functional theory （DFT）. Three kinds of possible reaction me...The surface disproportionation reaction mechanism of aluminum subchloride on the aluminum （100） surfaces has been investigated by the plane-wave density functional theory （DFT）. Three kinds of possible reaction mechanism of AlCl disproportionation reaction on the aluminum （100） surfaces have been taken into account. The structures of reactants and products have been optimized, transition states have been confirmed and activation energies have been calculated. The adsorption energy of reactants and desorption energy of products have been determined. All of these have been employed to confirm the reaction mechanism and the rate determining step ofAlCl disproportionation reaction on the aluminum （100） surfaces.展开更多
High resolution electron energy loss spectroscopy (HREELS) has been used to investigate the adsorption and reaction of CO on the Mo(100)-c(2×2)N surface. CO directly adsorbed on the N atoms from the c(2×2) l...High resolution electron energy loss spectroscopy (HREELS) has been used to investigate the adsorption and reaction of CO on the Mo(100)-c(2×2)N surface. CO directly adsorbed on the N atoms from the c(2×2) layer to form isocyanate (NCO) surface species was found in addition to CO adsorbed on the molybdenum atoms at 120 K. indicating that both Mo and N atoms of the Mo(100)-c(2×2)-N surface are of high reactivities for CO adsorption.展开更多
The adsorption and reaction of O ＋ CN → OCN on Cu（100） are studied by using density functional theory and cluster model. Cu14 cluster model is used to simulate the surface. The calculated results show that the OCN...The adsorption and reaction of O ＋ CN → OCN on Cu（100） are studied by using density functional theory and cluster model. Cu14 cluster model is used to simulate the surface. The calculated results show that the OCN species with the molecule perpendicular to the surface via N atom （N-down） is more favorable than other adsorption models, and the N-down at the bridge site is the most favorable. For N-down, calculated OCN symmetric and asymmetric stretching frequencies are all blue-shifted compared with the calculated values of free and in good agreement with the experiments. The charge transfer from the surface to the OCN species leads to that the bonding of OCN to the metal surface is largely ionic. The present studies also show that CN with the molecule perpendicular to the surface via C atom （NC-down） at the top site is the most stable. Except NC-down at the top site, the calculated CN stretching frequencies are all red-shifted. With O coadsorbed at the hollow site, the adsorption of NC-down at the next nearest bridge or top site is energetically more favorable than that at the adjacent hollow site. The reaction of O ＋ CN → OCN on Cu（100） has no energy barrier via both Eley-Rideal and Langmuir-Hinshelwood processes.展开更多
The effects of Triton X-100(TX100),a nonionic surfactant, on Belousov-Zhabotinsky reactions(B-Z reactions),including H_2SO_4^+ malonic acid(MA)+KBrOs+Mn^(2+)and H_2SO_4+gallic acid(GA)+KBrO_3 systems,have been investi...The effects of Triton X-100(TX100),a nonionic surfactant, on Belousov-Zhabotinsky reactions(B-Z reactions),including H_2SO_4^+ malonic acid(MA)+KBrOs+Mn^(2+)and H_2SO_4+gallic acid(GA)+KBrO_3 systems,have been investigated.The results showed that the oscillation parameters(the induction period,average oscillation period,oscillation lasting time)in these B-Z reactions were changed suddenly near the critical micelle concen- tration(CMC)of TX100.The results were explained according to the mechanism of B-Z reaction and the properties of micelles of the surfactant.展开更多
The catalytic performance of co mmonly used heteropolyacids （H3PW12O40, H4SiW12O40 and H3PMO12O40 synthesis of 4,4＇-methylenedianiline （4,4＇-MDA） from aniline and formaldehyde was evaluated and the result showed ...The catalytic performance of co mmonly used heteropolyacids （H3PW12O40, H4SiW12O40 and H3PMO12O40 synthesis of 4,4＇-methylenedianiline （4,4＇-MDA） from aniline and formaldehyde was evaluated and the result showed that H4SiW12O40 with moderate acid strength exhibited the best catalytic performance. Then HaSiW12O40@MIL-100（Fe） was prepared by encapsulating H4SiW12O40 within the pores of MIL-100（Fe） to facilitate its recovery and reuse. The prepared H4SiW12O40@MIL-100（Fe） was characterized by means of FT-IR, N2 adsorption-desorption, XRD, TG and then the catalytic performance was evaluated. The result showed that H4SiW12O40 was highly dispersed in the pores of MIL-100（Fe）, and both the Keggin structure of HaSiW12O40 and the crystal skeleton structure of MIL-100（Fe） could be effectively/preserved. Furthermore, H4SiW12O40@ MIL-100（Fe） showed excellent catalytic performance under the following reaction conditions： a molar ratio of aniline to formaldehyde = 5, a mass ratio of catalyst to formaldehyde = 1.2, a reaction temperature of 120 ℃ and a reaction time of 6 h. Under the above reaction conditions, the conversion of aniline was 41.1%, and the yield and selectivity of 4,4＇-MDA were 81,6% and 79.2%, respectively. Unfortunately, an appreciable loss in the catalytic activity of the recovered H4SiW12O40@MIL-100（Fe） was observed because of the blocking of the pores and the change of the acidity resulted from the adsorption of alkaline organics such as aniline and 4,4＇-MDA. The adsorbed alkaline organics could be cleaned up when the recovered catalyst was washed by methanol and DMF. Then the catalyst was effectively reused up to three cycles without much loss in its activity.展开更多
The CO-NO catalytic reaction on body-centred cubic （bcc） lattice is studied by Monte Carlo simulation. The simple Langmuir-Hinshelwood （LH） mechanism yields a steady reactive window, which is separated by continuo...The CO-NO catalytic reaction on body-centred cubic （bcc） lattice is studied by Monte Carlo simulation. The simple Langmuir-Hinshelwood （LH） mechanism yields a steady reactive window, which is separated by continuous and discontinuous irreversible phase transitions. The effect of precursor mechanism on the phase diagram of the system is also studied. According to this mechanism, the precursor motion of CO molecules is considered only on the surface of bcc lattice. Some interesting observations are reported.展开更多
基金Supported by the Joint Funds of the National Natural Science Foundation of China(No.u0837604) the Funds for Applied Basic Researches of Yunnan Province(No.2010CD022)
文摘The surface disproportionation reaction mechanism of aluminum subchloride on the aluminum （100） surfaces has been investigated by the plane-wave density functional theory （DFT）. Three kinds of possible reaction mechanism of AlCl disproportionation reaction on the aluminum （100） surfaces have been taken into account. The structures of reactants and products have been optimized, transition states have been confirmed and activation energies have been calculated. The adsorption energy of reactants and desorption energy of products have been determined. All of these have been employed to confirm the reaction mechanism and the rate determining step ofAlCl disproportionation reaction on the aluminum （100） surfaces.
基金the financial support of this work by the National Natural Science Foundation of China!29873048 ,29873042
文摘High resolution electron energy loss spectroscopy (HREELS) has been used to investigate the adsorption and reaction of CO on the Mo(100)-c(2×2)N surface. CO directly adsorbed on the N atoms from the c(2×2) layer to form isocyanate (NCO) surface species was found in addition to CO adsorbed on the molybdenum atoms at 120 K. indicating that both Mo and N atoms of the Mo(100)-c(2×2)-N surface are of high reactivities for CO adsorption.
基金This research was supported by the National Natural Science Foundation of China (20273013, 20303002), the Educational Foundation of Fujian Province (2002F010), and the Foundation of State Key Laboratory of Structural Chemistry (020051) and Fuzhou University (2004XY04)
文摘The adsorption and reaction of O ＋ CN → OCN on Cu（100） are studied by using density functional theory and cluster model. Cu14 cluster model is used to simulate the surface. The calculated results show that the OCN species with the molecule perpendicular to the surface via N atom （N-down） is more favorable than other adsorption models, and the N-down at the bridge site is the most favorable. For N-down, calculated OCN symmetric and asymmetric stretching frequencies are all blue-shifted compared with the calculated values of free and in good agreement with the experiments. The charge transfer from the surface to the OCN species leads to that the bonding of OCN to the metal surface is largely ionic. The present studies also show that CN with the molecule perpendicular to the surface via C atom （NC-down） at the top site is the most stable. Except NC-down at the top site, the calculated CN stretching frequencies are all red-shifted. With O coadsorbed at the hollow site, the adsorption of NC-down at the next nearest bridge or top site is energetically more favorable than that at the adjacent hollow site. The reaction of O ＋ CN → OCN on Cu（100） has no energy barrier via both Eley-Rideal and Langmuir-Hinshelwood processes.
文摘The effects of Triton X-100(TX100),a nonionic surfactant, on Belousov-Zhabotinsky reactions(B-Z reactions),including H_2SO_4^+ malonic acid(MA)+KBrOs+Mn^(2+)and H_2SO_4+gallic acid(GA)+KBrO_3 systems,have been investigated.The results showed that the oscillation parameters(the induction period,average oscillation period,oscillation lasting time)in these B-Z reactions were changed suddenly near the critical micelle concen- tration(CMC)of TX100.The results were explained according to the mechanism of B-Z reaction and the properties of micelles of the surfactant.
基金Supported by the National Natural Science Foundation of China(21236001,21476058,21506046)
文摘The catalytic performance of co mmonly used heteropolyacids （H3PW12O40, H4SiW12O40 and H3PMO12O40 synthesis of 4,4＇-methylenedianiline （4,4＇-MDA） from aniline and formaldehyde was evaluated and the result showed that H4SiW12O40 with moderate acid strength exhibited the best catalytic performance. Then HaSiW12O40@MIL-100（Fe） was prepared by encapsulating H4SiW12O40 within the pores of MIL-100（Fe） to facilitate its recovery and reuse. The prepared H4SiW12O40@MIL-100（Fe） was characterized by means of FT-IR, N2 adsorption-desorption, XRD, TG and then the catalytic performance was evaluated. The result showed that H4SiW12O40 was highly dispersed in the pores of MIL-100（Fe）, and both the Keggin structure of HaSiW12O40 and the crystal skeleton structure of MIL-100（Fe） could be effectively/preserved. Furthermore, H4SiW12O40@ MIL-100（Fe） showed excellent catalytic performance under the following reaction conditions： a molar ratio of aniline to formaldehyde = 5, a mass ratio of catalyst to formaldehyde = 1.2, a reaction temperature of 120 ℃ and a reaction time of 6 h. Under the above reaction conditions, the conversion of aniline was 41.1%, and the yield and selectivity of 4,4＇-MDA were 81,6% and 79.2%, respectively. Unfortunately, an appreciable loss in the catalytic activity of the recovered H4SiW12O40@MIL-100（Fe） was observed because of the blocking of the pores and the change of the acidity resulted from the adsorption of alkaline organics such as aniline and 4,4＇-MDA. The adsorbed alkaline organics could be cleaned up when the recovered catalyst was washed by methanol and DMF. Then the catalyst was effectively reused up to three cycles without much loss in its activity.
文摘The CO-NO catalytic reaction on body-centred cubic （bcc） lattice is studied by Monte Carlo simulation. The simple Langmuir-Hinshelwood （LH） mechanism yields a steady reactive window, which is separated by continuous and discontinuous irreversible phase transitions. The effect of precursor mechanism on the phase diagram of the system is also studied. According to this mechanism, the precursor motion of CO molecules is considered only on the surface of bcc lattice. Some interesting observations are reported.
