Effect of using polyvinyl alcohol and polyvinyl pyrrolidone in the synthesis of octahedral molecular sieves

Abstract

Octahedral molecular sieves (OMS-2) have been reported as catalysts for oxidation reactions. Interest exists in improving the properties of these materials. Effects of using polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) in the synthesis of OMS-2 have been studied. The structure of OMS-2 was kept when PVA or PVP were used as indicated by XRD and Fourier transform infrared spectra data. The use of PVA or PVP promoted an increase in surface area (measured by Brunauer–Emmett–Teller) and a decrease in particle size (measured by XRD). Besides increasing surface area and decreasing particle size of OMS-2, PVA and PVP were useful to improve the film hardness of OMS-2 samples applied on glass surfaces as measured by the pencil hardness test, and Knoop microhardness test. Film hardness is an important property for possible applications of OMS-2 materials in continuous flow reactor systems. By using PVA or PVP as non-chelating agents, an increase in surface area from 59 to 114 (m 2/g), a decrease in particle size, from 29.8 to 12.1 nm, and a hardness value of 4H using the pencil hardness test, and 17.73 H K by Knoops micro hardness tests for OMS-2 prepared with PVA were observed.