COx hydrogenation to methanol and other hydrocarbons under mild conditions with Mo3S4@ZSM-5

Abstract

The hydrogenation of CO₂ or CO to single organic product has received widespread attentions. Here we show a highly efficient and selective catalyst, Mo₃S₄@ions-ZSM-5, with molybdenum sulfide clusters ([Mo₃S₄]ⁿ⁺) confined in zeolitic cages of ZSM-5 molecular sieve for the reactions. Using continuous fixed bed reactor, for CO₂ hydrogenation to methanol, the catalyst Mo₃S₄@NaZSM-5 shows methanol selectivity larger than 98% at 10.2% of carbon dioxide conversion at 180 °C and maintains the catalytic performance without any degeneration during continuous reaction of 1000 h. For CO hydrogenation, the catalyst Mo₃S₄@HZSM-5 exhibits a selectivity to C₂ and C₃ hydrocarbons stably larger than 98% in organics at 260 °C. The structure of the catalysts and the mechanism of CO_x hydrogenation over the catalysts are fully characterized experimentally and theorectically. Based on the results, we envision that the Mo₃S₄@ions-ZSM-5 catalysts display the importance of active clusters surrounded by permeable materials as mesocatalysts for discovery of new reactions.

A series of materials containing Mo-S clusters confined in zeolitic cages of ZSM-5 are reported and shown to be efficient for CO₂ or CO hydrogenation with >98% selectivity to methanol, stable over 1000 h, or C₂ and C₃ hydrocarbons, stable over 100 h.