Influence of Carbon Content in Ni-Doped Mo2C Catalysts on CO Hydrogenation to Mixed Alcohol

Zhenjiong Hao,Ye Tian,Noritatsu Tsubaki,Xiaoshen Li,Tong Ding,Guohui Yang,Qingxiang Ma,Xingang Li

doi:10.3390/catal11020230

Abstract

Herein, we synthesize the Ni-doped Mo2C catalysts by a one-pot preparation method to illuminate the effect of the number of carbon atoms in Mo2C lattice on CO hydrogenation to mixed alcohol. The Ni doping inhibits the agglomeration of Mo2C crystals into large particles and the surface carbon deposition, which increase the active surface area. In addition, the interaction between Ni and Mo increases the electron cloud density of Mo species and promotes the non-dissociative adsorption and insertion of CO. Especially, our results indicate that with the increase of the nickel content, the number of carbon atoms in Mo2C lattice on the surface of the catalyst shows a volcano type variation. The low carbon content induces the formation of coordination unsaturated molybdenum species which exhibit the higher catalytic activity and mixed alcohol selectivity than other molybdenum species. Among the catalysts, the MC-Ni-1.5 catalyst with Ni/Mo molar ratio of 1.5:8.5, which has the largest amount of coordination unsaturated molybdenum species, shows the highest space-time yield of mixed alcohols, which is three times higher than that of the Mo2C catalyst.

Highlights

Mixed alcohol can be used as clean fuels to replace fossil energy and as solvents, intermediates of chemical raw materials and gasoline additives [1,2,3,4]
Four kinds of catalysts are commonly used in CO hydrogenation to mixed alcohol: Rh-based catalysts [7,8,9,10], Mo-based catalysts [11,12,13,14], modified Fischer–Tropsch synthesis catalysts [15,16,17,18] and modified methanol synthesis catalysts [19,20]
CO hydrogenation to mixed alcohol is often accompanied by side reactions such as Fischer–Tropsch synthesis to hydrocarbon and water gas shift

Summary

Introduction

Mixed alcohol can be used as clean fuels to replace fossil energy and as solvents, intermediates of chemical raw materials and gasoline additives [1,2,3,4]. Four kinds of catalysts are commonly used in CO hydrogenation to mixed alcohol: Rh-based catalysts [7,8,9,10], Mo-based catalysts [11,12,13,14], modified Fischer–Tropsch synthesis catalysts [15,16,17,18] and modified methanol synthesis catalysts [19,20]. Molybdenum carbide catalysts are widely used in CO or CO2 hydrogenation to mixed alcohol [21,22,23], water gas shift [24,25], methanol steam reforming [26,27,28], methane dry reforming [29] and so on. CO hydrogenation to mixed alcohol is often accompanied by side reactions such as Fischer–Tropsch synthesis to hydrocarbon and water gas shift. It is necessary to improve the selectivity of alcohol by catalyst modification [31,32,33,34,35,36]

Methods

Results

Conclusion