载体制备方法对Ni/ZrO2催化剂甲烷自热重整制合成气性能的影响

摘要

采用不同方法制备了ZrO2载体并进一步制备了用于甲烷自热重整制合成气反应的Ni/ZrO2催化剂，通过XRD、N2吸附和TEM等方法研究了ZrO2载体的结构对Ni/ZrO2催化剂的结构及催化性能的影响。实验结果表明，引入超声技术和增加置换醇凝胶步骤可显著改善ZrO2载体的结构特征，进而获得性能优异的Ni/ZrO2催化剂；金属Ni粒子结构稳定且尺寸较小有利于甲烷自热重整反应的进行。同时引入超声技术和增加置换醇凝胶步骤制备的Ni/ZrO2催化剂的性能最佳，在反应温度800℃、反应压力0.1 MPa、甲烷空速18000 mL/（g·h）、n（CH4）∶n（O2）∶n（H2O）=1∶0.25∶1、反应时间5 h的条件下，甲烷和水的转化率、CO和H2的选择性分别达96.5%，63.8%，81.7%，100.0%，此时产物中H2/CO摩尔比为3.3。%Four ZrO2 supports were prepared by different methods and then were used in the preparation of Ni/ZrO2 catalysts for methane autothermal reforming to syngas. The effects of the support structure on the structures and activities of the Ni/ZrO2 catalysts were investigated by means of XRD,nitrogen adsorption and TEM. It was revealed that,both the ultrasonic technique and the replacement of ZrO(OH)2 hydrogel with ZrO(OH)2 alcogel could improve the structural features of ZrO2 and the activities of the Ni/ZrO2 catalysts. The small size and stable structure of metallic Ni particles were benefi cial to the methane autothermal reforming. Under the reaction conditions of 800℃,0.1 MPa,n(CH4)∶n(O2)∶n(H2O) 1∶0.25∶1,GHSV of methane 18 000 mL/(g·h) and 5 h,the methane conversion,water conversion,CO selectivity and H2 selectivity over the Ni/ZrO2 catalyst which was prepared from ZrO(OH)2 alcogel by the ultrasonic method reached 96.5%, 63.8%,81.7% and 100.0%, respectively.