The time of flight mass spectrometer coupled with a laser ablation/supersonic expansion cluster source and a fast flow reactor was adopted to study the reactivity of cationic vanadium oxide clusters(VmOn+) toward acet...The time of flight mass spectrometer coupled with a laser ablation/supersonic expansion cluster source and a fast flow reactor was adopted to study the reactivity of cationic vanadium oxide clusters(VmOn+) toward acetylene(C2H2) molecules under gas phase(P,～ 1.14 kPa),under near room temperature(T,～ 350 K) conditions.Association products,VmOnC2H2+(m,n = 2,4;2,6;3,7―8;4,9―11;5,12―13;6,13―16,and 7,17),are observed.The oxidation of C2H2 by(V2O5)+n(n = 1―3) is experimentally identified.The reactivity of(V2O5)+ n decreases as n increases.Density functional theory(DFT) calculations were carried out to interpret the reaction mechanisms.The DFT results indicate that a terminal oxygen atom from V2O5+ can transfer overall barrierlessly to C2H2 at room temperature,which is in agreement with the experimental observation.Other experimental results such as the observation of V2O6C2H+2 and non-observation of V2O7,8C2H+2 in the experiments are also well interpreted based on the DFT calculations.The reactivity of vanadium oxide clusters toward acetylene and other hydrocarbons may be considered in identifying molecular level mechanisms for related heterogeneous catalysis.展开更多
Density functional theory (DFT) study of reaction between vanadium trioxide cluster cation (VO3+) and ethylene (C2H4) to yield VO2+ + CH3CHO (acetaldehyde) and VO2CH2+ + HCHO (formaldehyde) is carried out. Structures ...Density functional theory (DFT) study of reaction between vanadium trioxide cluster cation (VO3+) and ethylene (C2H4) to yield VO2+ + CH3CHO (acetaldehyde) and VO2CH2+ + HCHO (formaldehyde) is carried out. Structures of all reactants, products, intermediates, and transition state in the reaction have been optimized and characterized. The results show unexpected barriers in the reaction due to the existence of a η2-O2 moiety in the ground state structure of VO3+. The initial reaction steps combining ethylene adsorption, C=C activation and O-O cleavage are proposed as rate limiting processes. Comparison of reactions of VO3+ + C2H4 with VO3 + C2H4 and VO2+ + C2H4 in the previous studies is made in detail. The results of this work may shed light on the understanding of C=C bond cleavage in related heterogeneous catalysis.展开更多
The reactivity of sulfur dioxide (SO2) molecules toward iron oxide cationic clusters (FemOn+) is studied by a homemade time-of-flight mass spectrometer coupled with a laser ablation/supersonic expansion cluster source...The reactivity of sulfur dioxide (SO2) molecules toward iron oxide cationic clusters (FemOn+) is studied by a homemade time-of-flight mass spectrometer coupled with a laser ablation/supersonic expansion cluster source and a fast flow reactor. The association products FemOnSO2+ can be observed for most of the clusters. The interesting result is that the cooperation effect of SO2 and water is in favor of the adsorption of gas phase water on specific scale iron oxide clusters (Fe2O2+ and Fe3O3+ ). The reactivity information obtained may be useful to investigate atmospheric heterogeneous chemistry of related systems.展开更多
基金Supported by the Knowledge Innovation Program of Chinese Academy of Sciences (Grant Nos.KJCX2-YW-N24,and KZCX2-YW-205)the Hundred Talents Funds,National Natural Science Foundation of China (Grant Nos.20577052,20673123 and 20703048)National Basic Research Program of China (Grant No.2006CB403701 and 2006CB932100)
文摘The time of flight mass spectrometer coupled with a laser ablation/supersonic expansion cluster source and a fast flow reactor was adopted to study the reactivity of cationic vanadium oxide clusters(VmOn+) toward acetylene(C2H2) molecules under gas phase(P,～ 1.14 kPa),under near room temperature(T,～ 350 K) conditions.Association products,VmOnC2H2+(m,n = 2,4;2,6;3,7―8;4,9―11;5,12―13;6,13―16,and 7,17),are observed.The oxidation of C2H2 by(V2O5)+n(n = 1―3) is experimentally identified.The reactivity of(V2O5)+ n decreases as n increases.Density functional theory(DFT) calculations were carried out to interpret the reaction mechanisms.The DFT results indicate that a terminal oxygen atom from V2O5+ can transfer overall barrierlessly to C2H2 at room temperature,which is in agreement with the experimental observation.Other experimental results such as the observation of V2O6C2H+2 and non-observation of V2O7,8C2H+2 in the experiments are also well interpreted based on the DFT calculations.The reactivity of vanadium oxide clusters toward acetylene and other hydrocarbons may be considered in identifying molecular level mechanisms for related heterogeneous catalysis.
基金Supported by the Hundred Talents FundChinese Academy of Sciences and National Natural Science Foundation of China (Grant No. 20703048)
文摘Density functional theory (DFT) study of reaction between vanadium trioxide cluster cation (VO3+) and ethylene (C2H4) to yield VO2+ + CH3CHO (acetaldehyde) and VO2CH2+ + HCHO (formaldehyde) is carried out. Structures of all reactants, products, intermediates, and transition state in the reaction have been optimized and characterized. The results show unexpected barriers in the reaction due to the existence of a η2-O2 moiety in the ground state structure of VO3+. The initial reaction steps combining ethylene adsorption, C=C activation and O-O cleavage are proposed as rate limiting processes. Comparison of reactions of VO3+ + C2H4 with VO3 + C2H4 and VO2+ + C2H4 in the previous studies is made in detail. The results of this work may shed light on the understanding of C=C bond cleavage in related heterogeneous catalysis.
基金Supported by the Knowledge Innovation Program of the Chinese Academy of Sci-ences(Grant Nos. KJCX2-YW-N24, KZCX2-YW-205)the Major State Basic Re-search Development Program of China and Technology of China(Grant No. 2006CB-403701)the National Natural Science Foundation of China (Grant Nos. 40830101, 20673123)
文摘The reactivity of sulfur dioxide (SO2) molecules toward iron oxide cationic clusters (FemOn+) is studied by a homemade time-of-flight mass spectrometer coupled with a laser ablation/supersonic expansion cluster source and a fast flow reactor. The association products FemOnSO2+ can be observed for most of the clusters. The interesting result is that the cooperation effect of SO2 and water is in favor of the adsorption of gas phase water on specific scale iron oxide clusters (Fe2O2+ and Fe3O3+ ). The reactivity information obtained may be useful to investigate atmospheric heterogeneous chemistry of related systems.
