Preparation Of Ionic Liquid-based Catalyst Molybdenum Carbide CO.'S 2 Reaction Hydrogenated

The reaction of CO2 hydrogenation for methanol is a high efficient way of CO2 chemical utilization.Among the various catalysts of CO2 hydrogenation,?-Mo2C has been widely concerned due to their high thermal stability,high anti-toxicity and high catalytic activity.However,the methanol selectivity is still low to date in the continuous CO2 hydrogenation.Therefore,how to make ?-Mo2C show high selectivity of methanol is still a challenge.With salt mixture of benzoate and molybdophosphate as precursors,series of N,P doped C@Mo2C catalysts have been prepared by changing the composition and n(C)/n(Mo)of precursors.The doped heteroatoms(N,P)in catalysts can serve as basic sites which improve the surficial adsorption amount of CO2.Under optimized reaction conditions(3.0 MPa,220 ? 3600 mL·h-1·g-1),N,P-dC@Mo2C-MA-2-35 catalyst has shown excilient catalytic activity for 110 hours,where the CO2 conversion and methanol selectivity are 12.0%and 57.5%,respectively.In order to improve the methanol selectivity,N,S doped C@Mo2C catalysts have been prepared with the mixed salts of p-toluenesulfonate and ammonium molybdate as precursors.The results show that precursor species,carbonization temperature and n(C)/n(Mo)of precursors have a significant influence on the catalyst structure and catalytic performance.N,S-dC@Mo2C-CI-35-800 catalyst has high content of surface basic sites(pyridine N,S-C bonds)and the highest(Mo?+Mo?)/Mototai value,which is favorable for methanol production.Under optimized reaction conditions(3.0 MPa,220?,3600 mL·h-1·g-1),N,S-dC@Mo2C-CI-35-800 shows good catalytic performance with CO2 conversion of 16.2%and methanol selectivity of 91.0%,and stable catalytic activity within 110 hours.For purpose of further increasing the yield of methanol,the mixed-salts of p-toluenesulfonate and molybdophosphate as precursors were carbonized to obtain serious of N,P,S doped C@Mo2C catalysts.The effect of precursor species,carbonization temperature and n(C)/n(Mo)on structure and catalytic performance of catalysts has been studied.N,P,S-dC@Mo2C-BI-25-800 catalyst has high dispersion of Mo2C nanocrystals,high proportion of Mo? and Mo? and high content of basic sites(pyridine N,S-C bonds),which is beneficial to the generation of methanol.Meanwhile,carbon matrix doped by N,P,S atoms can also accelerate splitting and spillover of H2 towards absorbed CO2 for the production of methanol.Under optimized reaction conditions(3.0 MPa,200 ?,3600 mL·h-1·g-1),N,P,S-dC@Mo2C-BI-25-800 shows excellent catalytic result with CO2 conversion of 19.1%and methanol selectivity of 91.0%and good catalytic acticity in 110 hours.