Binderless ZrO2/HZSM-5 fibrillar composites by electrospinning as catalysts for the dimethyl ether-to-olefins process

Abstract

The upscaling of zeolitic materials to technical catalysts implies the formulation of the active phase with additives that can affect catalytic performance. As an alternative, we herein present fibrillar ZrO2/HZSM-5 composites prepared by electrospinning where HZSM-5 zeolite aggregates are joint through inert ZrO2 fibers. For zeolite loadings of 5, 10 and 20 wt% and SiO2/Al2O3 ratios of 30, 50 and 80, well-dispersed zeolite aggregates smaller than 1.5 μm have been observed. The ZrO2/HZSM-5 composites were tested as catalysts in the dimethyl ether-to-olefins (DTO) process. The maximum olefin selectivity (ca. 70%) but fastest deactivation was observed for a zeolite loading of 5 wt%, with side reaction extent being promoted when increasing zeolite loading or density of acid sites. A comparison with a technical catalyst suggested that secondary reactions are limited due to the homogeneous distribution of the zeolite in the fibrillary material and to the higher accessibility of zeolite crystals.