Highly dispersed Ni-Cu/SiO2 synthesized by sol-gel method for prompting direct deoxygenation of m-cresol to toluene
Ni based catalysts are relatively cheap and active for hydrodeoxygenation(HDO)of lignin biomass derived phenolic compounds to produce aromatics,but they suffer from the C—C hydrogenolysis under mild conditions.Herein,highly dispersed Ni/SiO2,Cu/SiO2 and bimetallic Ni-Cu catalysts with different Cu content were prepared by sol-gel method,and tested for HDO of m-cresol at 350℃ and atmospheric pressure.Although bare Ni/SiO2 with Ni size of 2nm showed high activity and toluene selectivity,significant C—C hydrogenolysis activity toward CH4 and benzene were observed.Ni and Cu in bimetallic Ni-Cu catalysts could interact each other and form Ni-Cu alloy after reduced.Toluene were the dominant product over optimal bimetallic catalyst(Cu/Ni molar ratio of 3)at all conversion levels.At m-cresol conversion of 97.2％,the yields of toluene and aromatics reached 85.0％and 91.6％,respectively.Analysis of intrinsic reaction rate and activation energy indicates that the addition of Cu enhances the direct deoxygenation toward toluene by inhibiting the competitive C—C hydrogenolysis reaction.
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