TPR法研究轻油转化制氢催化剂还原性能——CeO2促进还原的研究

用TPR法研究了烃类蒸气转化制氢催化剂还原性能。发现这类催化剂的还原符合核化模型。镍与催化剂中其它组分相互作用影响催化剂的还原, MgO和水泥的加入均提高了NiO的还原温度,稀土氧化物的加入可降低NiO-MgO体系的还原温度。由TPR曲线峰形分析求得了RKN,TDRE-3和ICI-46-1以及其它含CeO_2催化剂还原动力学参数。发现CeO_2的加入减少了催化剂的还原活化能, 且还原活化能与镍的分散度之间有较好的对应关系, 即镍铈比(Ni/Ce)分散得越均匀, 则还原活化能越低。提出了CeO_2促进还原的机理。

A STUDY OF REDUCTION OF NICKEL CATALYSTS FOR NAPHTHA STEAM REFORMING BY TPR

The reducibility of hydrocarbon-steam reforming catalysts has been studies by temperature programmed reduction (TPR) method. We found that the reduction mechanism of these catalysts is in accordance with nucleation model. The interaction between nickel and other components present in catalysts affects their reduction property. Addition of MgO and cement into those catalysts lead to an increase in their reduction temperature. A decrease in reduction temperature, however, has been observed by adding rare earth oxides.The reduction kinetic parameters of Ni catalysts with or without CeO_2 have been obtained from the peak analysis of their TPR curves. It has been found that CeO_2 promotes the reduction process by decreasing its activation energy. There is a good correlation between the reduction activation energy and the degree of dispersion of Ni, the higher the dispersion, the lower the activation energy. A mechanism of the promoting effect on reduction by CeO_2 has been suggested.