Micro‐Mesoporous Hierarchical Beta Zeolite and its Catalytic Application in Acetic Acid Benzylation

Abstract

AbstractHierarchical Beta zeolite with tailor‐made pore structure is prepared by post‐synthetic alkali (NaOH) treatment. XRD, FE‐SEM, ICP‐OES, 27Al & 29Si MAS NMR, and N2 sorption isotherms were used to explore the structural transformation of these materials. ICP‐OES analysis showed post‐synthetic base treatment resulting into tuning of the Si/Al ratio, thereby increasing the acidity of the sample. The acidic properties of materials were measured using acid‐base titration, Pyridine FTIR spectroscopy, and NH3‐TPD. Conversion of acetic acid to benzyl acetate by reacting with benzyl alcohol was studied using hierarchical and parent sample. The reaction was evaluated with theoretical and experimental approaches. Under optimum reaction conditions, desilicated Beta zeolite showed 93 % acetic acid conversion and 90 % benzyl acetate selectivity, as confirmed by GC and GC‐MS analyses. Theoretical analysis indicated direct relationship between rate constant and rising reaction temperature, in accordance with the principles of first‐order reaction kinetics (R2>0.95). The activation energy for acetic acid benzylation over Beta‐0.1 M NaOH was found to be 10.21 kJ mol−1, considerably lower value compared to previous reports.