镁助剂改性Pd/Al2O3甲烷催化燃烧催化剂:Mg/Al物质的量比对催化剂载体及活性物种形成的影响

Pd/Al2O3 catalysts modified with Mg for catalytic combustion of methane: Effect of Mg/Al mole ratios on the supports and active PdOx formation

本文研究了系列不同含量镁助剂改性的Pd/Al2O3催化剂的甲烷催化燃烧反应。研究表明,随着镁添加量的增加,载体由Al2O3转变为尖晶石型MgAl2O4,进一步增加Mg/Al物质的量比至3∶1时,形成了Mg(Al)Ox固溶体;催化剂中活性相Pd物种以金属Pd,PdOx或Pd-载体复合氧化物形式存在,各物种的相对含量以及PdPdO间的转化能力存在一定的差异。PdOx物种表现为具有较高的低温活性,而金属Pd和Pd-载体复合氧化物的高温活性较好。当Mg/Al物质的量比为1∶3时,催化剂的PdPdO转化能力最强,表现出了最高的甲烷催化燃烧反应活性。

Pd/Al2O 3 catalysts modified by different amount of magnesium were fabricated for catalytic combustion of methane (CCM).After the introduction of different amount of magnesium,Al2O 3,MgAl2O 4-like mixed oxide and Mg(Al)O x solid solution were formed.Owing to the formation of distinguished supports,the supported Pd species,i.e.metallic Pd,PdO x and support-Pd oxide complex were formed,and they were quite different in relative content and Pd PdO transformation ability.It was found that PdO x was active at low temperature,while metallic Pd particles and support-Pd oxide complex were active at high reaction temperature.The one with Mg/Al mole ratio of1∶3 was the most easily in Pd PdO transformation,demonstrating the best catalytic activity towards CCM reaction.