Cu-doped zeolites for catalytic oxidative carbonylation: The role of Bronsted acids

The aim of this work was to establish the role of RI-misted acidic sites in Cu-doped zeolites for the oxidative carbonylation of ethanol to diethyl carbonate (DEC). In order to eliminate the influences of other factors such as channel structure, faujasite (FAU) with different SiO2/Al2O3 ratios and Beta before and after passivation were investigated. Fourier Transform infrared spectroscopy (FTIR) of pyridine adsorption indicated that all of Bronsted acidic sites were exchanged with CuCl to form effective active sites for oxidative carbonylation. Characterization data showed that passivation on Beta zeolites has little effect on surface area and pore volume distribution except RI-misted acidic sites. The relationship between Bronsted acidic sites and catalyst activity was built on different types of zeolite supports. Diffuse reflectance infrared Fourier transform spectroscopy (DIRFTS) of CO adsorption revealed that the location of Cu active sites was related to the distribution of Bronsted acidic sites, which also influenced catalytic performance of oxidative carbonylation. (C) 2012 Elsevier B.V. All rights reserved.