Synthesis, characterization and catalytic properties of vanadium substituted hexagonal mesoporous aluminophosphate molecular sieves

Abstract

Vanadium substituted hexagonal mesoporous aluminophosphate (VHMA) molecular sieves were synthesized hydrothermally. Various physicochemical studies, viz., XRD, TEM, DRUV–VIS, EPR, N2 sorption were used to find the location of vanadium ions in the VHMA matrix and to check the mesoporosity of the sample. The catalytic activity of VHMA was evaluated, under mild reaction conditions, for the oxidation of cyclohexane reaction, which mainly gave cyclohexanol and cyclohexanone along with a very small amount of a secondary product, viz., cyclohexyl acetate. A comparative study, with other vanadium containing molecular sieves, viz., VMCM-41, VAPO-5 and VS-1, on the application of VHMA catalyst reveal that the latter exhibits excellent activity, selectivity and stability to leaching for the oxidation reaction of cycloalkanes, including bulkier molecules such as cyclododecane.