One-pot hydrothermal preparation of SBA-15 supported Keggin-type 12-tungstophosphoric heteropolyacid mesoporous material and its bifunctional catalytic performance

Abstract

In this work, a series of 12-tungstophosphoric acid (HPW) catalysts supported on mesoporous molecular sieves SBA-15 were prepared by a one-pot hydrothermal method and their physical and chemical properties were characterized by various techniques such as fourier transform infrared spectroscopy, powder X-ray diffraction, nitrogen adsorption–desorption and transmission electron microscopy. It has been found that all the catalysts retained the mesopore structure of SBA-15 and the primary Keggin-type structure of heteropoly acid. The surface areas and pore volumes of HPW-SBA-15 decreased with the increase of HPW heteropoly acid loadings. HPW units were mostly encapsulated inside the mesopores of SBA-15. The prepared catalysts showed excellent multifunctional catalytic properties. Their bifunctional catalytic performances were examined by photo-catalytic degradation of rhodamine-B dye and microwave-catalytic synthesis of isoamyl acetate. The sample with 20 wt% loading of 12-tungstophosphoric acid was found to be more active than the other catalysts under the photo and microwave-catalytic reaction conditions. Accordingly, reasons for the catalytic activity difference were simply explicated by the effect of HPW concentration on the physicochemical characteristic of HPW-SBA-15 catalysts such as surface areas, porosity, and mesostructure.