Abstract:

Pd_xPt_y-ZSM-5/Cordierite monolithic catalysts were prepared on the surface of the cordierite honeycomb supports, via vacuum extraction and one coating method, in which ZSM-5 molecular sieve, alumina sol, platinum or palladium nitrates and water were used as raw materials to prepare molecular sieve slurry. Effects of Pd loading, Si/Al ratio of ZSM-5, the mass ratio of Pd/Pt on the catalytic performance of the monolithic catalysts for the catalytic combustion of propane were investigated. The monolithic catalysts were characterized by ultrasonic oscillation, SEM, XRD, H₂-TPR and C₃H₈-TPD. When the ball milling time is 60 min and the molecular sieve slurry solid content is 38%, the coating amount of the monolith catalyst can reach 178 g?L^-1, and the coating detachment rate is less than 0.5%. Pd₂Pt₃-ZSM-5/Cordierite catalyst (total loading of noble metals of 1.2 g?L^-1 ) exhibits better catalytic activity and stability (T₅₀=259℃, T₉₀=323℃) for the catalytic combustion of propane, which has better industrial application prospect. Lower Si/Al ratio of ZSM-5 and the interaction between Pd and Pt increase the amounts of adsorbed propane and surface active oxygen species, thus increases the catalytic performance of the monolithic catalyst.

Key words: propane, catalytic combustion, vacuum extraction and one coating method, monolithic catalyst, molecular sieves slurry, noble metals

摘要：

以ZSM-5分子筛、铝溶胶、硝酸钯、硝酸铂和水为原料制备分子筛浆料，采用真空抽提-一次涂覆法在堇青石蜂窝陶瓷载体表面制备出Pd_xPt_y-ZSM-5/Cordierite整体式催化剂，考察了Pd负载量、ZSM-5分子筛的硅铝比和Pd/Pt质量比对整体式催化剂的丙烷催化燃烧性能的影响，并用超声波振荡、SEM、XRD、H₂-TPR和C₃H₈-TPD等手段对整体式催化剂进行了表征。当球磨时间为60 min，分子筛浆料固含量为38%时，整体式催化剂的涂层上载量可达到178 g?L^-1，涂层脱落率低于0.5%。Pd₂Pt₃-ZSM-5/Cordierite整体式催化剂（贵金属总负载量为1.2 g?L^-1）对于丙烷的催化燃烧具有较好的催化活性（T₅₀=259℃，T₉₀=323℃）和稳定性，具有良好的工业应用前景，其中较低的ZSM-5分子筛硅铝比以及Pd和Pt之间的相互作用增加了对丙烷的吸附能力和表面活性氧物种的数量，从而提高了整体式催化剂的催化活性。

关键词: 丙烷, 催化燃烧, 真空抽提-一次涂覆法, 整体式催化剂, 分子筛浆料, 贵金属