Improved methanol-to-olefin reaction selectivity and catalyst life by CeO2 coating of ferrierite zeolite

Abstract

The catalytic performance of the methanol-to-olefin (MTO) reaction over ferrierite zeolite was improved greatly by introduction of a CeO2 coating that selectively masked the acid sites on the external surface of the catalyst. In the absence of this coating, significant deterioration of the catalytic performance was observed owing to coke formation on the external surface and resultant blockage of the portals. Selective coating of CeO2 on the external surface was investigated using transmission electron microscopy, temperature-programmed desorption of NH3, N2 adsorption–desorption isotherms, and xenon adsorption measurements to reveal the structure–activity relationship. The resulting catalytic performance of CeO2-coated ferrierite zeolite in the MTO reaction was similar to that of MFI or high-silica CHA zeolite. The observed preferential formation of C4,= and C6,=, ∼90% free of aromatics was obtained because of the negligible deposition of heavy coke. This work shows that selective CeO2 coating on ferrierite zeolite was effective during catalyst regeneration and hydrothermal aging, leading to extended catalyst life and improved selectivity for catalytic applications.