碱金属Rb掺锰对碳烟颗粒催化燃烧活性的影响

Influences of alkali metal Rb doped Mn as catalyst on catalytic combustion activity of soot particles

碳烟是导致雾霾天气的罪魁祸首,选用适宜的催化剂提高碳烟颗粒的催化活性,可有效消除其对人体和环境的危害。采用溶胶凝胶法在Mn_2O_3(三氧化二锰)中掺杂不同含量的碱金属Rb(铷),合成了类似水钠锰矿和锰钾矿结构的催化剂,并着重探讨了该催化剂的组成和结构对碳烟颗粒燃烧性能的影响。研究结果表明:Rb_(0.6)Mn的催化效果相对最佳,可使碳烟的T_m(碳烟转化率为50%时的温度)达到333℃;Rb_xMn催化剂表面覆盖的碱金属,使得催化剂与碳烟颗粒的表面接触性能因碱金属熔融盐之特性而降低;碱金属与Mn形成的特殊结构(即Rb离子在掺杂过程中会部分富集在催化剂表面),使Mn价态升高,表面氧物种缺陷位增多,从而提高了氧的流动性,进而促进了碳烟的催化燃烧。

The soot is the main culprit of haze weather, so the choosing suitable catalyst, which can improve the catalytic activity of soot particles, can effectively eliminate the harm to human body and environment. The catalyst with similar birnessite and crptomelane structures was synthesized when the different alkali metal Rb（rubidium） contents were introduced into Mn2O3（manganic oxide） by sol-gel method, and the influences of the composition and structure of the catalyst on the combustion behaviour of soot particles were emphatically discussed. The research results showed that the Rbo^Mn had the relatively best catalytic effect because it could make the T,~ （temperature at 50% soot＇s convemion rate ） of soot particles at 333 ~C. The surface of Rb^Mn catalyst was covered by alkali metal, so the surface contact properties between catalyst and soot particles were decreased due to the nature of alkali metal molten salt. The catalytic combustion of soot was promoted because the liquidity of oxygen was improved with increasing Mn valence and defect location of surface oxygen species when alkali metal and Mn form a special structure（namely the catalyst surface gathered partly by Rb ion in the doping process ）.