高分散Ru-PEGx/NaY催化对硝基甲苯加氢制对甲基环己胺

Hydrogenation of Paranitrotoluene to P-Methyl-Cyclohexylamine over Highly Dispersed Ru-PEGx/NaY Catalyst

摘要:

以聚乙二醇[PEG(400)]为分散剂，(NH4)2CO3水溶液为沉淀剂，采用浸渍沉淀法，制备了高分散的Ru-PEGx/NaY催化剂，利用XRD，TEM，H2-TPR，ICP-AES及XPS等手段对样品进行了表征。结果表明：适量的PEG（7.5 mL）可以包裹住Ru3+，增大Ru3+之间的排斥力，从而有效地阻止Ru3+的团聚。以对硝基甲苯液相（PNT）加氢制对甲基环己胺（PMC）为探针反应，以PNT转化率和PMC选择性为指标考察了不同Ru催化剂的催化性能。结果表明：Ru-PEG7.5/NaY的催化性能最优，在催化剂用量质量0.50 g，反应时间为35 min，H2压力3.5 MPa，反应温度160 ℃，对硝基甲苯5.00 g，搅拌速率900 r/min，300 mL异丙醇的条件下，PNT的转化率为100 %，PMC的选择性高达95.0 %。此外，发现Ru-PEG7.5/NaY催化剂重复使用5次后，活性未明显降低，说明其稳定性良好。

Abstract:

Highly dispersed Ru-PEGx/NaY catalyst was prepared by impregnation-precipitation method using PEG(400) as the dispersant and (NH4)2CO3 as the precipitant. The samples were characterized by XRD, TEM, H2-TPR, ICP-AES and XPS. The results showed that the suitable PEG(7.5 mL) could trap the Ru3+ ions, and then increased the repulsion among Ru3+ ions, thereby impeding the agglomeration of Ru particles. The catalytic performance of the different samples was evaluated via p-nitrotoluene (PNT) liquid-phase hydrogenation to p-methyl-cyclohexylamine (PMC) reaction, with the PNT conversion and PMC selectivity as indicator. The results indicated that the catalytic performance of Ru-PEG7.5/NaY was the most excellent, the PNT conversion and the selectivity of PMC were found to be as high as 100 % and 95.0 % under the optimum conditions which the amount of Ru-PEGx/NaY catalyst was 0.50 g, reaction time was 35 min, the pressure of H2 was 3.5 MPa, the reaction temperature was 160 ℃, the amount of PNT was 5.00 g, stirring rate was 900 r/min and isopropyl alcohol was 300 mL. In addition, It was found that the activity of Ru-PEG7.5/NaY changed almost nothing after the fifth run, indicating the Ru-PEG7.5/NaY catalyst has good stability.