CeO_(2)/H-beta系列催化剂的合成及其在氯苯催化燃烧中的应用

Preparation of CeO_(2)/H-beta Catalysts and Their Performances in Chlorobenzene Catalytic Combustion

以H-beta分子筛为载体,采用简单高效的浸渍法制备了一系列不同Ce金属含量的CeO_(2)/H-beta催化剂,包括3CeO_(2)/H-beta催化剂(w(Ce)=3%),4CeO_(2)/H-beta催化剂(w(Ce)=4%),5CeO_(2)/H-beta催化剂(w(Ce)=5%)和7CeO_(2)/H-beta催化剂(w(Ce)=7%).通过X-射线衍射(XRD)、扫描电子显微镜(SEM)观察、N_(2)吸脱附测试(BET)、高分辨透射电镜(HRTEM)观察和能谱仪(EDX)分析等手段对所合成催化剂进行表征,同时以氯苯为目标污染物,考察了催化剂在催化燃烧反应中的催化性能.结果表明:所合成的催化剂都具有典型的BEA结构,有较高的结晶度,且金属Ce负载量与理论值接近;负载CeO_(2)以后的催化剂在氯苯催化燃烧反应中的催化性能较H-beta分子筛明显提高,其中5CeO_(2)/H-beta催化剂具有更好的活性,当反应温度为320℃时,该催化剂对氯苯的转化率为80%,360℃时,氯苯已基本消除.

Hierarchically porous catalysts CeO_(2)/H-beta with different Ce contents were successfully synthesized through the green solvent-free method,including 3CeO_(2)/H-beta,4CeO_(2)/H-beta,5CeO_(2)/H-beta and 7CeO_(2)/H-beta catalysts with 3%,4%,5%,7%mass fractions of cerium,respectively.All these as-synthesized catalysts were characterized by the X-ray diffraction(XRD),scanning electron microscopy(SEM),nitrogen sorption measurements(BET),and high-resolution transmission electron microscope(HRTEM)with energy dispersive X-ray spectroscopy(EDX).Furthermore,their performances in catalytic combustion of chlorobenzene were investigated.The results show that the as-synthesized catalysts have good crystallinity which is in agreement with that of a BEA structure,and that the metal load capacity of 5CeO_(2)/H-beta is close to the theoretical value.As to the chlorobenzene catalytic combustion,catalysts loaded with CeO_(2) exhibit better catalytic properties than H-beta zeolite.Among these loaded catalysts,5CeO_(2)/H-beta shows better activity.When the temperature reaches 320℃,the conversion of chlorobenzene reaches 80%,and chlorobenzene could be almost eliminated eventually at a temperature of 360℃over 5CeO_(2)/H-beta catalyst.