整体式Pd/ZSM-5/Cordierite催化剂的制备及其低浓度甲烷燃烧催化性能

Preparation of monolithic Pd/ZSM-5/Cordierite catalyst for the combustion of lean methane

以蜂窝状堇青石(Cordierite)为载体,采用聚乙烯醇纤维(PVA)溶液辅助涂覆法制备了整体式Pd/ZSM-5/Cordierite催化剂;利用XRD、N2物理吸附、SEM和XPS等手段对催化剂的结构和性质进行了表征。将该催化剂用于低浓度甲烷催化燃烧,研究了PVA溶液浓度、活性组分负载方式和Pd负载量等因素对Pd/ZSM-5/Cordierite催化剂活性涂层稳定性及低浓度甲烷燃烧催化性能的影响。结果表明,以质量分数为3%的PVA溶液制备的分子筛浆料进行涂层涂覆,所得到的整体式催化剂活性涂层具有良好的牢固度。以Pd/ZSM-5为涂层粉体、Pd整体负载量为1.12‰(质量分数,下同)时,所制备的(Pd/ZSM-5)/Cordierite催化剂具有优异的低浓度甲烷(体积分数为1%)燃烧催化性能,甲烷转化率为10%、50%和90%时的反应温度分别为271、337和385℃。此外,在不同温度下435h长周期测试实验中,该整体式(Pd/ZSM-5)/Cordierite催化剂表现出较高的抗热稳定性,表明其具有良好的低浓度甲烷燃烧处理应用前景。

A monolithic Pd/ZSM-5/Cordierite catalyst was prepared by coating the active Pd/ZSM-5component on the Cordierite support with Polyvinyl alcohol(PVA)solution as an assistant agent,and its structure and physicochemical properties were characterized by XRD,N2 sorption,SEM,XPS and ICP-AES.The Pd/ZSM-5/Cordierite catalyst was applied in the combustionof lean methane and the effects of PVA concentration,active component loading mode and Pd loading on the coating stability and catalytic performance in lean methane combustion were then investigated.The results indicate that a stable coating of the active Pd/ZSM-5component can be achieved on the Cordierite support when the mass fraction of PVA in the PVA solution is 3%.With an overall Pd loading of 1.12‰ and Pd/ZSM-5as the coating powder,the(Pd/ZSM-5)/Cordierite catalyst exhibits excellent performance in the lean methane(1%)combustion.The reaction temperatures to reach a methane conversion of 10%,50%and 90%are as low as 271,337 and 385℃,respectively.Moreover,the monolithic(Pd/ZSM-5)/Cordierite catalyst also displays excellent stability in a long term test of 435 hfor the lean methane combustion at different temperatures,suggesting its enormous potential for the application in the mitigation of lean methane through catalytic combustion.