酸性、中性及碱性痕量气体在SO3+CH3OH大气反应中的催化机制研究
A catalytic mechanism for the SO3+CH3OH reaction with the acidic,neutral and basic trace gases
李荣荣 1丁超 1罗琴 1卫书琴 1李泽尧 1张田雷1
作者信息
- 1. 陕西理工大学 化学与环境科学学院,陕西 汉中 723000
- 折叠
摘要
硫酸氢甲酯(MHS)主要来源于三氧化硫(SO3)与甲醇(CH3OH)反应.作为大气潜在的成核物种,MHS对大气新粒子形成具有明显的促进作用.然而对于SO3 + CH3OH气相反应的研究仅局限于无痕量气体参与反应.基于此,采用量子化学方法CCSD(T)-F12a/cc-pVDZ-F12//M06-2X/6-311 +G(2df,2pd)结合主方程(ME/RRKM)理论对酸性(H2SO4)、中性(H2O)及碱性(NH3)痕量气体催化SO3 +CH3OH反应进行了理论研究.计算结果表明,H2O、H2SO4和NH3 的加入不仅使反应前中间体的稳定化能增加了0.5～7.3 kcal/mol,而且使反应能垒降低了至少14.9 kcal/mol.尤其是NH3 参与SO3 + CH3OH反应甚至为无势垒过程.有效速率常数计算结果表明,在0～15 km高度范围内,由于H2O的浓度远远大于H2SO4 和NH3,H2O催化反应的有效速率常数比H2SO4 和NH3 参与反应的对应值大了 3～8 个数量级.与对应SO3 +CH3OH反应的速率常数相比较,H2O参与反应的有效速率常数大了 8 个数量级,表明H2O对由SO3 与CH3OH形成MHS具有明显的促进作用.该研究为认识大气中酸性、中性及碱性痕量气体如何影响重要大气反应提供了新的见解.
Abstract
The reaction between sulfur trioxide(SO3)and methanol(CH3OH)can form the methyl hydrogen sulfate(MHS),which was recognized as a potential nucleating species and can effectively promote the new particles formation in atmospheric.However,the SO3+CH3OH reaction with acidic(H2SO4),neu-tral(H2O)and basic(NH3)trace gases have not been reported.Herein,the SO3+CH3OH reaction assisted by acidic(H2SO4),neutral(H2O)and basic(NH3)trace gases have been studied theoretically by using quantum chemical method of CCSD(T)-F12a/cc-pVDZ-F12//M06-2X/6-311 +G(2df,2pd)and the Master Equation(ME/RRKM)calculation.The calculation results showed that the addition of H2O,H2SO4 and NH3 has not only increased the stabilization energies of the pre-reactive complexes by0.5～7.3 kcal/mol,but also decreased the energy barriers by at least 14.9 kcal/mol.Moreover,the SO3+CH3OH reaction with NH3 is a barrierless process.Effective rate constant calculations suggest that H2O is 3～8 orders of magnitude more effi-cient catalyst than H2SO4 and NH3 within 0～15 km due to its relatively higher concentration.Meanwhile,the effective rate constants of H2O catalyzed reaction were 8 orders of magnitude larger than the rate constant of the SO3+CH3OH reaction.This indicates that the contribution of H2O is obvious in the SO3 + CH3OH reaction.This study will provide new insight for the effects of acidic,neutral and basic trace gases on the SO3+CH3OH reaction in the atmospheric environment.
关键词
SO3/CH3OH/有效速率常数/反应机理/催化剂Key words
SO3/CH3OH/effective rate constants/reaction mechanisms/catalyst引用本文复制引用
基金项目
国家自然科学基金(22073059)
陕西理工大学研究生创新基金(SLGYCX2304)
出版年
2024
NETL
NSTL
万方数据