低水碳比下新型甲烷蒸汽重整催化剂的研究

采用高温固相反应法制备了Ca0.08Mg0.03Al0.89Ox复合金属氧化物(CMAO)大孔载体,用ZrO2,Y2O3,CeO2对其进行修饰,再采用浸渍法制备了甲烷蒸汽重整Ni基催化剂;采用BET、X射线衍射、X射线光电子能谱、CO脉冲色谱、氢程序升温还原、氧程序升温氧化等技术对催化剂进行了表征,并考察了修饰物种和La2O3助剂对催化剂性能的影响。实验结果表明,ZrO2,Y2O3,CeO2修饰物种及La2O3助剂可提高催化剂表面Ni晶粒的分散度,从而提高催化剂的活性和抗积碳性能。Ni-La/Y2O3-ZrO2-CMAO催化剂在低水碳比(水蒸气与甲烷的摩尔比为2.5)时,对甲烷蒸汽重整反应表现出很高的活性,甲烷转化率高达95%,连续运转100h后活性未见下降。

Novel Catalyst for Methane Steam Reforming Under Low Ratio of Steam to Methane

A macroporous support Ca0.08Mg0.03Al0.89Ox(CMAO) was prepared by solid state reaction of MgO,CaO and a-Al2O3,and modified by ZrO2,Y2O3 or CeO2.Ni based catalysts supported on the obtained CMAO with different oxide modifiers were prepared by impregnation and was used in steam reforming of methane under low mole ratio of steam to CH4.The catalysts were characterized by means of BET,XRD,XPS,CO pulse chromatography,H2-TPR and O2-TPO techniques.Effects of different oxide modifiers ZrO2,Y2O3 or CeO2 and La2O3 as promoter on activities of Ni based catalysts were studied.La2O3,ZrO2,Y2O3 or CeO2 enhanced the dispersion of Ni crystalline particles on surfaces of catalysts,and hence promoted their catalytic activities and improved their anti-carbon deposition performance.Ni-La/Y2O3-ZrO2-CMAO catalyst gave a high methane conversion of 95% and good stability during on-steam time of 100 h at low mole ratio 2.5 of steam to CH4.No obvious lowering of catalyst activity was observed during the period.