Design And Preparation Of MoS₂-based Catalyst And Study Of The Performance For Syngas Conversion

The recent demand for renewable fuels has intensified research activities for conversion of biomass derived feedstocks.Therefore,synthesis of higher alcohols from syngas?CO/H₂?is receiving renewed interest.Higher alcohols are highly attractive due to their widespread application as fuels,fuel additives or intermediates in order to the synthesis of various and specialty products.Typically,higher alcohols synthesis catalysts can be classified into four categories.Mo-based catalysts are regarded as promising catalysts for production of higher alcohols because of its sulfur poisoning resistant ability and coking resistance.This work aims at the poor activity and alcohols selectivity of Mo catalyst,enhancing the HAS performance in terms of preparation method and active component and reaction-coupling.An effective method was developed for Mo-based supported catalysts by the combination of tungsten-doping and surfactant-assisted hydrothermal strategy.The tungsten-doping enhanced the interaction between Ni and W/Mo metal species forming more the Ni-Mo W-S phase with tunable slab size and stacking layers,and thus promoted the chain growth of alcohol to form a greater amount of higher alcohols in CO hydrogenation.The optimal K,Ni-Mo_0.75W_0.25/MMO-S exhibited a dominant double-layer structure??39.0%?and highly synergetic effects between Ni and W/Mo species,resulting in the highest total alcohol selectivity?76.1%?at CO conversion of7.4%.This work provides a new route for tuning the morphology of Mo S₂/WS₂ and synergetic effects between Ni and W/Mo species in supported catalysts to improve the selectivity of higher alcohols.An effective method was developed through the combination of a partially reduced Zn-Cr-Al trinary oxide and Mo-based catalysts,which dramatically increases the oxygenates selectivity to 63.6%at CO conversion of 9.7%.The appropriate balance between Zn-Cr-Al oxide and Mo-based catalyst promotes catalyst activity and selectivity to higher oxygenates due to synergetic effect of two components.The alkaline-doping process suppresses the acid site and stables alkoxy species,which further significantly enhances the selectivity of oxygenates at the negligible loss of activity.The appropriate proximity of the two components can effectively promotes the migration of reaction intermediate,resulting in the formation of the desired C₂₊products.