ZnO and TiO2 clusters as catalyst in the addition and abstraction reaction of acrylic acid with the OH radical

Abstract

AbstractThe present work displays the theoretical analysis on the role of metal oxide clusters as an effective catalyst in the reaction between acrylic acid and OH radical, which has an energy barrier of 12.4 kcal/mol. The formation of metal oxide cluster such as ZnO and TiO2 with varying size from monomer to hexamer is analyzed using cohesive energy, which increases with cluster size. Adsorption of acrylic acid on clusters reveals that dimer ZnO and tetramer TiO2 are good adsorbed entities. The dimer ZnO and tetramer TiO2 clusters have reduced the barrier height. However, from the thermodynamical analysis of H‐abstraction and OH addition reaction, the dimer ZnO cluster is found to be a good catalyst than a tetramer TiO2 cluster. The favorable H abstraction and OH addition reactions are feasible at the active methylene group (–CH). OH addition reactions dominate over the H abstraction reaction. Further, the presence of metal oxide clusters enhances the rate of the reaction between acrylic acid and OH radical. The kinetics of the favorable reaction with a dimer ZnO cluster has a rate constant of 7.80 × 10−11 cm3 molecule−1 s−1, which is higher than the literature report (1.75 × 10−11 cm3 molecule−1 s−1). Overall, ZnO and TiO2 metal oxide clusters can be effectively utilized as catalyst.