La-Ni-Mo-B非晶态催化剂的制备、加氢脱氧性能及失活研究

摘要

Amorphous La-Ni-Mo-B catalyst was prepared by chemical reduction method using NaBH4 as a reducing agent and characterized by BET, SEM, XRD and XPS. The hydrodeoxygenation of 4-methylphenol was used as a probe reaction to test its catalytic performance. The results showed that the additive La can decrease the particle size of the catalyst, increase the surface area, and promote the reduction of Ni2+ and Mo6+. The hydrodeoxygenation of 4-methylphenol follows the hydrogenation-dehydration route. The conversion of 4methylphenol and the selectivity to methylcyclohexane at 275 ℃ achieve 97％ and 96％, respectively. The aromatic content in products is much lower than that of fuel regulation Ⅲ in the world ( aromatics content ＜ 15％ ). The deactivation of the catalyst may be mainly attributed to the destruction of its amorphous structure during reaction.%以NaBH4为还原剂采用化学还原法制备La-Ni-Mo-B非晶态催化剂,用BET、SEM、XRD和XPS等手段对催化剂进行表征,以4-甲基苯酚为探针研究其加氢脱氧性能,并探讨了4-甲基苯酚的加氢脱氧反应路径.结果表明,助剂La的加入,减小了催化剂的粒径,增大了比表面积,促进Ni2+和Mo6+的还原.275℃时,4-甲基苯酚加氢脱氧转化率达97%,甲基环己烷选择性达96%,加氢脱氧反应按氢化-氢解路径进行,产物中芳烃含量明显低于世界燃油规范Ⅲ类油标准(芳烃的质量分数小于15%).催化剂活性降低的主要原因是由于Ni活性中心的非晶态结构被破坏.