Ce掺杂的OMS-2催化剂上二甲醚催化燃烧性能的研究

Catalytic combustion of dimethyl ether over Ce-doped cryptomelane-type manganese oxide

通过氧化还原法合成了氧化锰八面体分子筛(OMS-2),而后浸渍负载一定量的Ce。采用TG-DSC、XRD、低温氮气吸附-脱附、TEM、FT-IR、Uv-vis、O2-TPD、H2-TPR以及XPS等技术对制备材料的结构和氧化还原性能进行了表征,考察了催化剂的二甲醚催化燃烧反应性能。结果表明,低掺杂量的Ce高度分散在OMS-2中;高含量时存在独立的CeO2。光谱测试结果表明,Ce的掺杂并未对OMS-2的晶型产生影响。XPS结果表明,Ce的掺杂会提高OMS-2中晶格氧的量。O2-TPD和H2-TPR结果表明,制备的催化剂具有比较丰富的氧物种,低温下易还原,因而在二甲醚催化燃烧中表现出了良好的催化活性和热稳定性。起燃温度在160℃左右,完全燃烧温度在170℃左右,反应产物仅有二氧化碳和水,并且反应后催化剂晶型保持不变,没有积炭产生。

Manganese oxide octahedral molecular sieves（OMS-2） were synthesized by oxidizing MnSO4 with KMnO4 and then doped with Ce.The structure and oxidation activity of the catalysts were characterized by XRD,N2 adsorption-desorption,TEM,FT-IR,Uv-vis,O2-TPD,H2-TPR and XPS techniques.The catalytic activity for dimethyl ether（DME） combustion was also evaluated.The results showed that the highly-dispersed amorphous CeO2 exited when Ce-doping was low.However,the independent CeO2 formed when Ce-doping exceed 10%.XPS results show that the doped-Ce can improve the lattice oxygen of the catalyst.O2-TPD and H2-TPR characterization show that the Ce-OMS-2 catalysts have abundant facile lattice oxygen and can be easily reduced.Ce-OMS-2 display excellent performance in DME catalytic combustion,with a start-off temperature of 160℃ and a complete temperature of 170℃.CO2 and H2O are the only reaction products detected.The used catalyst keeps the same crystalline as the fresh,and there is no carbon deposition detected over the used catalyst.