Catalytic study of modified titanium silicalites-1 in the hydroxylation of alkyl benzene by hydrogen peroxide

Abstract

This research studies catalytic properties of TS-1 modified with Al, Co, V and Fe in the hydroxylation of alkyl benzene, i.e. toluene and ethyl benzene, with hydrogen peroxide. The results of toluene hydroxylation at 70°C for 2 h show that all catalysts produce reaction products as p-cresol, o-cresol, particularly TS-1 modified with Al and Fe also have benzaldehyde as predominant product. At 95°C, TS-1 and M-TS-1 (except Fe-TS-1) have benzaldehyde as major product accompany with p-cresol, o-cresol. The reaction temperature increase affects benzaldehyde selectivity as well as the total conversion of toluene to products because the raise in reaction temperature increase average energy of the reactant molecules untill can overcome the activation energy barrier and then convert to product. The predominant products obtained from ethyl benzene hydroxylation at 70°C and 95°C are acetophenone and 1-phenethyl ethanol. Other products, benzaldehyde is also produced in case using Co-TS-1 and Fe-TS-1. In addition, Fe-TS-1 also has phenethyl alcohol and phenyl acetaldehyde. The products formation mechanisms of toluene and ethyl benzene hydroxylations have two mechanisms i.e. the electrophilic aromatic substitution mechanism (o-cresol and p-cresol) and side chain oxidation (benzaldehyde and all products of ethyl benzene).