Lifetime improvement in methanol-to-olefins catalysis over chabazite materials by high-pressure H-2 co-feeds

Mitigating catalyst deactivation in the industrially deployed process of methanol-to-olefins conversion over HSAPO-34 is a critical challenge. Here, we demonstrate that lifetime in methanol-to-olefins catalysis over HSAPO-34 at sub-complete methanol conversion, as determined by the cumulative turnover capacity per Bronsted acid site towards hydrocarbon products in the effluent before complete catalyst deactivation (similar to 15% carbon final conversion), can be enhanced with increasing efficacy (similar to 2.8x to >70x) by co-feeding H-2 at increasing partial pressures (400-3,000 kPa) in the influent with methanol compared with cofeeding helium at equivalent pressures. The lifetime improvement in the presence of high-pressure H-2 co-feeds is observed to be more prominent at complete methanol conversion than at sub-complete conversion. The improvements in catalyst lifetime by co-feeding H-2 are rendered without any deleterious effects on C-2-C(4 )olefins selectivity, which remains similar to 85% carbon irrespective of the inlet H-2 pressure. These observations can be rationalized based on the participation of H-2 in hydrogen transfer reactions, and in effect, the interception of pathways that promote the formation of deactivation-inducing polycyclic species.