硫物种对负载型钯催化剂上氢吸附性质的影响

用X光光电子能谱(XPS)分析了负载型Pd/Al_2O_3催化剂上硫和钯的状态。以程序升温脱附-质谱(TPD-MS)方法研究了不同硫物种及不同气氛对催化剂氢吸附性质的影响。结果表明: 硫物种对氢吸附的影响按S_2~(2-)、S~(2-)、SO_4~(2-)的顺序减小, 且前两者的影响远比SO_4~(2-)的大。这与催化剂在H_2-O_2反应中的抗硫性评价结果一致。并用原子分子轨道理论对上述结果进行了讨论。

EFFECT OF SULFUR SPECIES ON H_2 ADSORPTION ON SUPPORTED PALLADIUM CATALYST

A series of supported palladium catalysts were prepared with impregnating method. SO_4~(2-) was introduced by dipping Al_2O_3 into dilute H_2SO_4 solution for the preparation of Pd/Al_2O_3--SO_4 or impregnating Pd/Al_2O_3 with a series of K_2SO_4 solutions for Pd/SO_4~(2-)/Al_2O_3 as catalysts. X-ray photoelectron spectroscopy was employed tomeasure the states of sulfur and palladium before and after the catalysts were treatedunder different atmospheres. Temperature programmed desorption-mass spectroscopy(TPD-MS) was used to investigate the effect of different sulfur species and atmo-sphere on H_2 adsorption on the catalysts.The results showed as follows: The influen-ce of sulfur species upon H_2 desorption declined in a order as S_2~(2-),S~(2-) and SO_4~(2-),and tbe effeet of the former two was more distinct than SO_4~(2-). Their behaviors werein accord with the evaluation of the catalyst for H_2-O_2 reaction, which may be in-terpreted with the molecular orbital theory.