制备方法对钯碳催化剂表面性质及其加氢性能影响

Performance of Pd/C catalysts by different preparation processes

采用浸渍法制备Pd/C催化剂,考察了浸渍方法、还原方法和条件对催化剂活性的影响,用XRD及XPS对催化剂进行表征,并用对苯二甲酸加氢精制体系进行活性评价,与工业上使用的进口Pd/C催化剂进行比较。结果表明:采用EDTA处理载体后,再分2次浸渍PdC l2溶液制备的0.5%Pd/C催化剂,表面Pd的摩尔分数可达8%以上,但对催化剂活性影响不显著;还原温度过高会使H2还原法制备出的催化剂中Pd晶粒变大,导致催化剂活性降低;采用甲酸钠还原和250℃下H2还原方法有利于提高催化剂活性。

Pd/C catalysts used for the hydrogenation of crude TA （ terephthalic acid） were prepared by impregnation method and were characterized by XRD,XPS techniques. Effects of impregnation method, reduction method and reduction conditions on the conversion of 4-CBA were investigated. Results showed that palladium content on the surface of Pd/C catalyst could exceed 8.0% when the EDTA-treated active carbon was impregnated PdCl2solution two times, however, little improvement on the catalytic activity was observed. Reduction by sodium formate and by hydrogen at 250 ℃ were favorable to improve the conversion of 4-CBA, while reduction by hydrogen at higher temperature increased of the crystal size of Pd and decreased of the catalytic activity.