The G3 and CBS-QB3 theoretical methods are employed to study the decomposition of CF3OH into FCFO and HF by water, water dimmer, and ammonia. The decomposition of CF3OH into FCFO and HF is unlikely to occur in the atm...The G3 and CBS-QB3 theoretical methods are employed to study the decomposition of CF3OH into FCFO and HF by water, water dimmer, and ammonia. The decomposition of CF3OH into FCFO and HF is unlikely to occur in the atmosphere due to the high activated energy of 88.7 k J/mol at the G3 level of theory. However, the computed results predict that the barrier for unimolecular decomposition of CF3OH is decreased to 25.1 kJ/mol from 188.7 k J/mol with the aid of NH3 at the G3 level of theory, which shows that the ammonia play a strong catalytic effect on the split of CF3OH. In addition, the calculated rate constants show that the decomposition of CF3OH by NH3 is faster than those of H2O and the water dimmer by 10^9 and 10^5 times respectively. The rate constants combined with the corresponding concentrations of these species demonstrate that the reaction CF3OH with NH3 via TS4 is of great importance for the decomposition of CF3OH in the atmosphere.展开更多
Alastraet： The gas-based direct reduction of iron ore pellets was carried out by simulating the typical gas composition in coal gasification process, Midrex and HyMII processes. The influences of gas composition and ...Alastraet： The gas-based direct reduction of iron ore pellets was carried out by simulating the typical gas composition in coal gasification process, Midrex and HyMII processes. The influences of gas composition and temperature on reduction were studied. Results show that the increasing of HE proportion is helpful to improve the reduction rate. However, when ~o（H2）：~o（CO）〉1.6：1, changes of HE content have little influence on it. Appropriate reduction temperature is about 950 ℃, and higher temperature （1 000 ℃） may unfavorably slow the reduction rate. From the kinetics analysis at 950 ℃, the most part of reduction course is likely controlled by interfacial chemical reaction mechanism and in the final stage controlled by a combined effect of gaseous diffusion and interfacial chemical reaction mechanisms. From the utilizations study of different reducing gases at 950 ℃, the key step in reduction course is the 3rd stage （FeO→Fe）, and the utilization of reducing gas increases with the rise of HE proportion.展开更多
Reactions of gas-phase species with small molecules are being actively studied to understand the elementary steps and mechanistic details of related condensed-phase processes.Activation of the very inert N≡N triple b...Reactions of gas-phase species with small molecules are being actively studied to understand the elementary steps and mechanistic details of related condensed-phase processes.Activation of the very inert N≡N triple bond of dinitrogen molecule by isolated gas-phase species has attracted considerable interest in the past few decades.Apart from molecular adsorption and dissociative adsorption,interesting processes such as C-N coupling and degenerate ligand exchange were discovered.The present review focuses on the recent progress on adsorption,activation,and functionalization of N2 by gas-phase species(particularly metal cluster ions)using mass spectrometry,infrared photo-dissociation spectroscopy,anion photoelectron spectroscopy,and quantum chemical calculations including density functional theory and high-level ab initio calculations.Recent advances including characterization of adsorption products,dependence of clusters’reactivity on their sizes and structures,and mechanisms of N≡N weakening and splitting have been emphasized and prospects have been discussed.展开更多
CO2 is a major greenhouse gas,and it can also be used as a chemical feedstock for synthesis of chemicals and fuels by passing the petrochemical source.Herein,we present the recent progress of our research work in the ...CO2 is a major greenhouse gas,and it can also be used as a chemical feedstock for synthesis of chemicals and fuels by passing the petrochemical source.Herein,we present the recent progress of our research work in the catalytic conversion of CO2 to chemicals,with particular attention paid to catalytic reactivity and reaction mechanism.We also give the recommendations regarding the challenges and potential directions of the future research in this field.展开更多
基金This work was supported by the National Natural Science Foundation of China （No.10865003） and the Guizhou University for Nationalities （2010）. The authors thank professors W. T. Duncan, R. L. Bell, and T. N. Truong or providing the rate program through the internet.
文摘The G3 and CBS-QB3 theoretical methods are employed to study the decomposition of CF3OH into FCFO and HF by water, water dimmer, and ammonia. The decomposition of CF3OH into FCFO and HF is unlikely to occur in the atmosphere due to the high activated energy of 88.7 k J/mol at the G3 level of theory. However, the computed results predict that the barrier for unimolecular decomposition of CF3OH is decreased to 25.1 kJ/mol from 188.7 k J/mol with the aid of NH3 at the G3 level of theory, which shows that the ammonia play a strong catalytic effect on the split of CF3OH. In addition, the calculated rate constants show that the decomposition of CF3OH by NH3 is faster than those of H2O and the water dimmer by 10^9 and 10^5 times respectively. The rate constants combined with the corresponding concentrations of these species demonstrate that the reaction CF3OH with NH3 via TS4 is of great importance for the decomposition of CF3OH in the atmosphere.
基金Project(50725416) supported by National Natural Science Funds for Distinguished Young Scholars of China
文摘Alastraet： The gas-based direct reduction of iron ore pellets was carried out by simulating the typical gas composition in coal gasification process, Midrex and HyMII processes. The influences of gas composition and temperature on reduction were studied. Results show that the increasing of HE proportion is helpful to improve the reduction rate. However, when ~o（H2）：~o（CO）〉1.6：1, changes of HE content have little influence on it. Appropriate reduction temperature is about 950 ℃, and higher temperature （1 000 ℃） may unfavorably slow the reduction rate. From the kinetics analysis at 950 ℃, the most part of reduction course is likely controlled by interfacial chemical reaction mechanism and in the final stage controlled by a combined effect of gaseous diffusion and interfacial chemical reaction mechanisms. From the utilizations study of different reducing gases at 950 ℃, the key step in reduction course is the 3rd stage （FeO→Fe）, and the utilization of reducing gas increases with the rise of HE proportion.
基金supported by the National Natural Science Foundation of China(No.21833011 and No.21973101)the Youth Innovation Promotion Association CAS(No.2020034)the K.C.Wong Education Foundation。
文摘Reactions of gas-phase species with small molecules are being actively studied to understand the elementary steps and mechanistic details of related condensed-phase processes.Activation of the very inert N≡N triple bond of dinitrogen molecule by isolated gas-phase species has attracted considerable interest in the past few decades.Apart from molecular adsorption and dissociative adsorption,interesting processes such as C-N coupling and degenerate ligand exchange were discovered.The present review focuses on the recent progress on adsorption,activation,and functionalization of N2 by gas-phase species(particularly metal cluster ions)using mass spectrometry,infrared photo-dissociation spectroscopy,anion photoelectron spectroscopy,and quantum chemical calculations including density functional theory and high-level ab initio calculations.Recent advances including characterization of adsorption products,dependence of clusters’reactivity on their sizes and structures,and mechanisms of N≡N weakening and splitting have been emphasized and prospects have been discussed.
基金the financial support from the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA02040602)the National Science&Technology Pillar Program(2013BAC11B02)
文摘CO2 is a major greenhouse gas,and it can also be used as a chemical feedstock for synthesis of chemicals and fuels by passing the petrochemical source.Herein,we present the recent progress of our research work in the catalytic conversion of CO2 to chemicals,with particular attention paid to catalytic reactivity and reaction mechanism.We also give the recommendations regarding the challenges and potential directions of the future research in this field.
