Abstract:

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.

Key words: catalysis, biomass, renewable energy, m-cresol, hydrodeoxygenation, Ni-Cu alloy

摘要：

在木质素生物质衍生的酚类化合物加氢脱氧生产芳烃中，Ni基催化剂兼具经济性与活性，然而，在温和条件下会受到C—C氢解的影响。在此，采用溶胶-凝胶法制备了高分散的Ni/SiO₂、Cu/SiO₂和不同Cu含量的双金属Ni-Cu催化剂，并在350℃和常压条件下对其进行间甲酚加氢脱氧性能测试。尽管Ni粒径约为2nm的单金属Ni/SiO₂表现出高的活性和甲苯选择性，但C—C氢解生成甲烷和苯的反应仍然显著。对于双金属Ni-Cu催化剂，Ni和Cu相互作用并在还原后形成Ni-Cu合金。在最佳的双金属催化剂（Cu/Ni摩尔比约为3）上，甲苯在所有转化水平上都是主要产物。当间甲酚转化率为97.2%时，甲苯和芳烃的收率分别达到85.0%和91.6%。本征反应速率和活化能分析表明，Cu的引入通过抑制竞争性的C—C氢解反应，促进了直接脱氧生成甲苯。

关键词: 催化, 生物质, 再生能源, 间甲酚, 加氢脱氧, Ni-Cu合金