title: Hydrolysis of Sulfur Dioxide in Small Clusters of Sulfuric Acid: Mechanistic and Kinetic Study.
abstract: The deposition and hydrolysis reaction of SO2 + H2O in small clusters of sulfuric acid and water are studied by theoretical calculations of the molecular clusters SO2-(H2SO4)n-(H2O)m (m = 1,2; n = 1,2). Sulfuric acid exhibits a dramatic catalytic effect on the hydrolysis reaction of SO2 as it lowers the energy barrier by over 20 kcal/mol. The reaction with monohydrated sulfuric acid (SO2 + H2O + H2SO4 - H2O) has the lowest energy barrier of 3.83 kcal/mol, in which the cluster H2SO4-(H2O)2 forms initially at the entrance channel. The energy barriers for the three hydrolysis reactions are in the order SO2 + (H2SO4)-H2O > SO2 + (H2SO4)2-H2O > SO2 + H2SO4-H2O. Furthermore, sulfurous acid is more strongly bonded to the hydrated sulfuric acid (or dimer) clusters than the corresponding reactant (monohydrated SO2). Consequently, sulfuric acid promotes the hydrolysis of SO2 both kinetically and thermodynamically. Kinetics simulations have been performed to study the importance of these reactions in the reduction of atmospheric SO2. The results will give a new insight on how the pre-existing aerosols catalyze the hydrolysis of SO2, leading to the formation and growth of new particles.
authors.affiliation: Institute of Theoretical Chemistry, Jilin University , Changchun 130023, People's Republic of China.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Liu
authors.affiliation: Institute of Theoretical Chemistry, Jilin University , Changchun 130023, People's Republic of China.
authors.forename: Sheng
authors.initials: S
authors.lastname: Fang
authors.affiliation: Institute of Theoretical Chemistry, Jilin University , Changchun 130023, People's Republic of China.
authors.forename: Zhixiu
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Institute of Theoretical Chemistry, Jilin University , Changchun 130023, People's Republic of China.
authors.forename: Wencai
authors.initials: W
authors.lastname: Yi
authors.affiliation: Department of Chemistry and Biochemistry, California State University , Fullerton, California 92834, United States.
authors.forename: Fu-Ming
authors.initials: FM
authors.lastname: Tao
authors.affiliation: Institute of Theoretical Chemistry, Jilin University , Changchun 130023, People's Republic of China.
authors.forename: Jing-Yao
authors.initials: JY
authors.lastname: Liu
mesh_terms: D001272:Atmosphere / Q000737:chemistry; D002384:Catalysis; D006868:Hydrolysis; D007700:Kinetics; D008968:Molecular Conformation; D013458:Sulfur Dioxide / Q000737:chemistry*; D013464:Sulfuric Acids / Q000737:chemistry*; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
chemical_list: D013464:Sulfuric Acids; D014867:Water; D013458:Sulfur Dioxide; C033158:sulfuric acid