K、Mn助剂协同效应对Fe基催化剂上CO加氢制低碳烯烃反应性能的影响

Effects of Mn-K synergistic action on iron-based catalyst for CO hydrogenation to light olefins

采用典型方法制备了不同Fe、Mn、K比例的铁基催化剂,利用X射线粉末衍射、N2吸附/脱附、扫描电镜、拉曼光谱、H2-TPR等手段对催化剂进行了表征,并考察了催化剂对CO加氢制低碳烯烃反应的催化性能。结果表明,Mn能有效促进活性相分散,抑制碳链增长,但Fe-Mn强相互作用不能有效增加低碳烃烯/烷比,α-Fe2O3作为活性铁物种前驱体对烯烃生成反应更加有利。K通过减少Mn以氧化物形式出现,增加FeMn化合物晶格缺陷,从而最终使Fe-Mn-K催化剂低碳烯烃收率显著高于Fe-Mn和Fe-K体系。

The catalyst samples with different Fe,Mn and K proportions were prepared by the typical method. The catalyst were characterized by X-ray diffraction（ XRD）, N2-adsorption, Raman, scanning electron microscope（ SEM） and their performance for CO hydrogenation to light olefins was investigated. The results showed that the incorporation of Mn with appropriate contents can improve the dispersion of the active phase and suppress the carbon chain growth. The interaction of Fe-Mn can not effectively increase olefin / paraffin ratio. Active iron species precursor（ α-Fe2O3） are more advantageous to olefin formation reaction. Mn oxides are restrained by the addition of K,giving rise to more crystal defects of FeMn compound. As a result,a higher yield of light olefins is acquired for Fe-Mn-K than Fe-Mn and Fe-K catalytic system.