论文部分内容阅读
采用CCSD(T)/aug-cc-p VTZ//B3LYP/6-311+G(2df,2p)方法对n(H_2O)(n=0,1,2)参与HO_2+NO→HNO_3反应的微观机理和速率常数进行了研究.结果表明,由于水分子与HO_2形成的复合物(H_2O…HO_2,HO_2…H_2O)结合NO与水分子形成的复合物(NO…H_2O,ON…H_2O)的反应方式具有较高能垒和较低有效速率,其对HO_2+NO→HNO_3反应的影响远小于双体水(H_2O)2与HO_2(或NO)形成复合物然后再与另一分子反应物NO(或HO_2)的反应方式,因此n(H_2O)(n=1,2)催化HO_2+NO→HNO_3反应主要经历了HO_2…(H_2O)_n(n=1,2)+NO和NO…(H_2O)_n(n=1,2)+HO_22种反应类型.由于HO_2…(H_2O)_n(n=1,2)+NO反应的低能垒和高速率,HO_2…(H_2O)_n(n=1,2)+NO反应优于NO…(H_2O)_n(n=1,2)+HO_2反应.与此同时,由于计算温度范围内HO_2…H_2O+NO反应的有效速率常数比HO_2…(H_2O)2+NO反应对应的有效速率常数大了10~12数量级,可推测(H_2O)_n(n=1,2)催化HO_2+NO→HNO_3反应主要来自于单个水分子.此外,在216.7~298.6 K范围内水分子对HO_2+NO→HNO_3反应起显著的正催化作用,且随温度的升高有明显增大的趋势,在298.2 K时增强因子k’RW1/ktotal达到67.93%,表明在实际大气环境中水蒸气对HO_2+NO→HNO_3反应具有显著影响.
The microstructure of n (H_2O) (n = 0,1,2) involved in the reaction of HO_2 + NO → HNO_3 with CCSD (T) / aug-cc-p VTZ // B3LYP / 6-311 + G (2df, 2p) Mechanism and rate constants were studied.The results show that the reaction between water molecule and HO 2 (H 2 O ... HO 2, HO 2 ... H 2 O) and the combination of NO with water molecule (NO ... H 2 O, ON ... H 2 O) Has a higher energy barrier and lower effective rate, and its effect on the reaction of HO 2 + NO → HNO 3 is much less than that of the complex of H 2 O 2 and HO 2 (or NO) and then with the other molecular reactant NO (or HO 2 Therefore, the reaction of HO 2 + NO → HNO 3 catalyzed by n (H 2 O) (n = 1,2) mainly underwent the reaction of HO 2 H 2 O 2 + NO and NO 2 H 2 O 3 + (H 2 O) n (n = 1, 2) + HO_, due to the low energy barrier and high rate of HO 2 ... (H 2 O) n The NO reaction is superior to the reaction of NO_ (H_2O) _n (n = 1,2) + HO_2, and at the same time the effective rate constant of HO_2 ... H_2O + NO is higher than that of HO_2 (H_2O) 2 + NO The corresponding effective rate constants are on the order of 10-12, suggesting that the reaction of HO 2 + NO → HNO 3 catalyzed by (H 2 O) _n (n = 1,2) mainly comes from a single water molecule.In addition, In the range of 16.7 ~ 298.6 K, the water molecules played a significant positive catalysis on the reaction of HO_2 + NO → HNO_3, with a marked increase trend with the increase of temperature. At 298.2 K, the enhancement factor k’RW1 / ktotal reached 67.93% It shows that water vapor has a significant effect on the reaction of HO 2 + NO → HNO 3 in the real atmosphere.