Surface reactions of CuCl2 and HY zeolite during the preparation of CuY catalyst for the oxidative carbonylation of methanol

A CuI/Y catalyst was prepared for the vapor phase oxidative carbonylation of methanol to dimethyl carbonate (DMC). The surface solid-state interactions of CuCl2 with HY zeolite were studied using thermogravimetry. The surface properties and morphologies of catalyst samples were analyzed by thermogravimetry, X-ray photoelectron spectroscopy, and elemental analysis, and their catalytic performance was assessed in a fixed-bed reactor. Both CuCl and CuCl2 were found to co-exist on the external surface of the catalyst, while ion-exchanged CuI along with small amounts of adsorbed CuCl were contained in the internal Y zeolite cage structures. Both the CuCl and CuCl2 were active species during the DMC synthesis. Compared with a conventional CuI/Y catalyst prepared by heating a mixture of CuCl and HY zeolite, the CuI/Y catalyst prepared by heating a mixture of CuCl2 and HY zeolite showed increased catalytic activity for the oxidative carbonylation of methanol, even though it had lower Cu and Cl contents.

Graphical AbstractA Cu/Y(CuCl2) catalyst was prepared by heating a combination of CuCl2 and HY zeolite, and exhibited higher catalytic activity for the oxidative carbonylation of methanol compared with a conventional Cu/Y catalyst generated by heating a mixture of CuCl and HY zeolite, even though it had lower Cu and Cl contents. In this catalyst, both CuCl and CuCl2 were present on the surface and ion-exchanged CuI and low levels of adsorbed CuCl were in the internal Y zeolite cage structure.Figure optionsDownload full-size imageDownload as PowerPoint slide