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通过 SEM,TGA,BET比表面积测定 ,对影响 Pd/C催化剂耐用性诸因素进行了研究。表明芳硝基化合物加氢过程中 Pd/C催化剂活性衰退的主要原因是反应过程中原料中的杂质在催化剂表面的机械覆盖及高温引起的热衰退所致。改用经精制提纯后的原料 ,选择适宜的反应条件 ,可使催化剂的活性及耐用性得到较大改善。本研究以实验室制备的 2 % Pd/C为催化剂 ,经提纯的工厂中间体产品 m-β-羟乙基砜硝基苯为原料 ,在 65℃、3.5MPa、乙醇为溶剂、原料∶乙醇∶催化剂 =1∶ 1∶ 0 .0 5(wt)的条件下反应 2 h,加氢转化率可达 99.7%。催化剂经反复使用 5次后 ,在上述反应条件下反应 5h,加氢转化率仍保持 81 .5%。
The factors affecting the durability of Pd / C catalyst were studied by SEM, TGA and BET specific surface area. The results show that the main reason for the decay of Pd / C catalyst activity during the hydrogenation of anthryl nitro compounds is the mechanical coverage of impurities on the catalyst surface during the reaction and the thermal decay caused by high temperature. Switch to the purified raw materials, select the appropriate reaction conditions, the catalyst activity and durability can be greatly improved. In this study, 2% Pd / C prepared in laboratory was used as the catalyst. The purified m-β-hydroxyethyl sulfone nitrobenzene was used as raw material in 65 ℃, 3.5MPa and ethanol as the raw materials, ethanol : Catalyst = 1: 1: 0. 0 5 (wt) under the conditions of 2 h, hydroconversion rate up to 99.7%. After repeated use of the catalyst for 5 times, the reaction was carried out under the above reaction conditions for 5 hours, and the conversion rate of hydrogenation remained at 81.5%.