甘油合成2-甲基吡嗪的催化剂及工艺研究

Catalysts and Reaction Parameters for Synthesis of 2-Methyl pyrazine (2-MP) from Glycerol

摘要:

采用沉淀法制备了经Al、Cr、Cu和Zn等掺杂的Ni/SiO2催化剂，用于甘油与乙二胺固定床气相催化缩环制2-甲基吡嗪(2-MP)，并详细考察了催化剂焙烧温度、反应温度、载气空速和原料液水含量对缩环反应的影响。结果表明，ZnO物种可使Ni/SiO2催化剂同时具有适量的酸位与碱位，有助于甘油与乙二胺分子的活化，从而使2-MP的收率得以提高；焙烧温度对Ni-Zn/SiO2催化性能的影响较为重要，500 oC最佳；Ni-Zn/SiO2催化甘油与乙二胺缩环反应的最佳工艺条件为：反应温度为380 oC、载气N2空速150 h-1、原料液中水质量分数为70%，此时甘油与乙二胺的转化率均为100%，2-MP收率为66.4%。

Abstract:

Ni/SiO2 catalysts modified by Al, Cr, Cu and Zn were prepared by precipitation and applied in fixed-bed gas-phase catalytic cyclization of ethanediamine (EDA) with glycerol to 2-methylpyrazine (2-MP) in the present work. And at the same time, the effects of calcination and reaction temperature, GHSV and water content on the catalytic properties of Ni-Zn/SiO2 in cyclization were also investigated. The results indicated that the presence of ZnO led to the simultaneous production of acidic and alkali sites over Ni-Zn/SiO2, which was helpful to the activation of EDA and glycerol molecules and 2-MP formation through cyclization was improved. It was also found that the calcination temperature was an important factor on affecting the catalytic property of catalysts in cyclization. And Ni-Zn/SiO2 calcined at 500 oC exhibited the highest 2-MP yield of 66.4% along with complete conversion towards glycerol and EDA was obtained over Ni-Zn/SiO2 catalyst under the optimum reaction conditions: reaction conditions 380 oC, GHSV of carrier N2 150 h−1, water content in fed reaction liquid 70%.