碱金属改性Pd/γ-Al_2O_3催化剂三效性能的研究  

ALKALI METAL PROMOTION OF Pd/_γAl_2O_3 CATALYSTS OPERATED UNDER SIMULATED THREE-WAY CONDITIONS

作　　者：姚青[1] 田群[1] 陈宏德[1] 房师平[1] 韩芸[1] 沈迪新[1] 

机构地区：[1]中国科学院生态环境研究中心,北京100085

出　　处：《环境化学》2005年第4期370-373,共4页Environmental Chemistry

摘　　要：考察了碱金属对氧化铝负载钯催化剂的改性作用,发现钾的作用最为明显,其三效起燃温度可降低50℃以上.在氧化还原数S=1.0和5=1.5两种条件下进行对比,表明碱金属的掺入可以拓宽催化剂的操作窗口.低电负性碱金属的掺入,一方面增强了电负性物种CO,NO和O2的吸附能力,同时减弱了电正性物种C3H6的吸附能力,另一方面,削弱了吸附态分子NO中N-O键的键能,促进其解离,抑制了N2O的生成.Alkali metal promotion strongly enhances the performance of Pd/γ-Al2O3 catalysts operated under simulated three-way conditions at S = 1. 0 and S = 1. 5. The optimally promoted catalyst with 11. 4wt. % K exhibits a -50℃ lower light-off temperature than the unpromoted sample when tested under stoichiometry feed conditions. The promotion is due to the effects of alkali metals acting to increase the adsorption strength of electronegative adsorbates (CO, NO and O2) and decrease the one of electropositive adsorbates (C3H6) . The addition of alkali metals weakens the N-O bond in the adsorbed molecule, and therefore facilitates NO dissociation.

关 键 词：Pd/γ-Al2O3催化剂 碱金属 改性作用 三效性能 吸附能力 电正性物种 

分 类 号：X132[环境科学与工程—环境科学]