Abstract
Oxidative coupling of methane (OCM) is a promising single-step route to convert natural gas to high-valued chemicals. It is generally agreed that Mn-Na-W catalysts offer a balanced conversion-selectivity trade-off. The present work outlines a novel SiC-SiO2 support synthesized by spray drying to extend the lifetime of the catalyst. Incorporating SiC into the support enables the exothermic reaction heat to be effectively dissipated, avoiding hotspots and thermal shocks, and increasing the thermal resistance. The spray drying technique yields particles with a consistent distribution of SiC inside the particles, amplifying the thermal resistance of the catalyst. Our kinetic results show that the spray dried catalyst with SiC has significantly higher stability at high C-2 selectivity compared to the benchmark SiO2-supported catalyst prepared by wetness impregnation. This result is due to (1) the more uniform distribution of active phases and SiC provided by the spray drying methodology and (2) the greater thermal resistance provided by SiC, which avoids thermal shocking and stabilizes the Mn-Na-W phases during the longterm (70 h) stability test for OCM.