以同时具有介孔和微米级大孔的新型多级孔道Al2O3整体柱为载体,Ce,Zr为助剂,制备得到Pd/Al2O3整体式催化剂,研究了催化剂的超低浓度风排瓦斯甲烷催化燃烧的反应性能,并结合实验结果,对Pd/Zr/Al2O3催化剂上甲烷燃烧的催化反应路径进行了探索分析.研究结果表明:所合成的添加助剂Ce,Zr的Pd/Al2O3催化剂的超低浓度甲烷氧化低温活性较好,催化剂保留了载体原有的特殊微观结构,比表面积仍然较大,有利于提高催化剂的反应活性.其中助剂Zr的助催性能比Ce的高.推测Pd/Zr/Al2O3催化剂上甲烷氧化的催化反应路径为:在助剂Zr的作用下,吸附在PdO-Pd活性位上的CH4分子中一个C-H键的强度被削弱,小于H与PdO表面晶格中O原子的键合强度,从而导致一个H原子从CH4分子中脱出,速控步骤完成后反应快速进行,生成CO2和H2O.%Pd/Al2O3 monolithic catalysts were prepared using Al2O3 porous material with both mesopores and three-di mensional interconnected macropores as the support and Ce,Zr as additives.Ultra-low concentration ventilation air methane combustion activity on the as-synthesized catalysts was investigated and the reaction path was predicted.Results show that the reaction performance of catalysts with the additives is excellent owing to the maintained special microstructure of the original support and large BET surface value.Pd/Al2O3 catalysts with additive Zr have a better reaction activity than addition of Ce.The possible reaction path of CH4 catalytic combustion on Pd/Zr/Al2O3 catalyst was predicted as follows:one of the C-H bonding strength in the molecule CH4 adsorbed on the PdO-Pd active sites aredecreased with the help of additive Zr to be lower than that of bonding strength between H and atom O in the PdO surface lattice,resulting in the escape of one atom H from the molecule CH4 and the accomplishment of the controlling step.CO2 and H2O are generated quickly after that process.
展开▼
