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Pd O—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Pd O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 / Al2 O3 monolithic catalysts were prepared using Al2 O3 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. Re- sults show that the reaction performance of catalysts with the additives is excellent owing to the maintained special mi- crostructure of the original support and large BET surface value. Pd / Al2 O3 catalysts with additive Zr have a better re- action activity than addition of Ce. The possible reaction path of CH4 catalytic combustion on Pd / Zr / Al2 O3 catalyst was predicted as follows:one of the C—H bonding strength in the molecule CH4 adsorbed on the PdO-Pd active sites are decreased with the help of additive Zr to be lower than that of bonding strength between H and atom O in the PdO sur- face lattice,resulting in the escape of one atom H from the molecule CH4 and the accomplishment of the controlling step. CO2 and H2 O are generated quickly after that process.