论文部分内容阅读
本工作利用XPS研究了用于F-T合成的加K助剂的Fe-Mn超细粒子催化剂的表面结构,考察了制备方法和预处理条件对催化剂表面结构的影响。在合成气处理条件下,伴随着Mn向表面迁移并产生富集。催化剂表面显著富K;适当的Mmt和富集有利于提高低碳烯烃选择性,同时活性不会明显降低。催化剂还原可以用“内还原模型”来描述,依还原程度不同。表面形成不同的Fe~3+、Fe~(?)、Fe_3O_4、x-Fe(?)C(?)、Mn~(3+)、Mn~(3+)的混合物,Mn的加入促进了表面铁物种的还原与碳化,合成气氛下,催化剂表面形成了三种不同的表面碳物种:烃类碳、石墨型碳(284.6eV)以及碳化物碳(283.2eV)。
In this work, the surface structure of Fe-Mn ultrafine particle catalyst used for F-T synthesis with K promoter was studied by XPS. The influence of preparation method and pretreatment conditions on the surface structure of catalyst was investigated. Under syngas processing conditions, Mn migrates to the surface with enrichment. The surface of the catalyst is significantly enriched in K; appropriate Mmt and enrichment are favorable for increasing the selectivity of light olefins, while their activity is not significantly reduced. Catalyst reduction can be described by the “internal reduction model”, depending on the degree of reduction. The formation of a mixture of different Fe ~ 3 +, Fe ~ (?), Fe 3 O 4, x Fe Fe 3 C, Mn 3+ and Mn 3+ promoted the surface Iron species reduction and carbonization, the synthesis of the atmosphere, the catalyst surface formed three different surface carbon species: hydrocarbon carbon, graphite carbon (284.6eV) and carbon carbide (283.2eV).