Effect of reducing agents on microstructure and catalytic performance of precipitated iron-manganese catalyst for Fischer-Tropsch synthesis

详细信息    查看全文

• 作者：Mingyue Ding^a ; ^b ; Yong Yang^b ; ^{yyong@sxicc.ac.cn} ; Baoshan Wu^b ; Tiejun Wang^a ; Hongwei Xiang^b ; Yongwang Li^b
• 关键词：Fischer&ndash ; Tropsch synthesis ; Iron-based catalyst ; Reducing agents ; Iron carbides ; Mö ; ssbauer effect spectroscopy
• 刊名：Fuel Processing Technology
• 出版年：2011
• 出版时间：December, 2011
• 年：2011
• 卷：92
• 期：12
• 页码：2353-2359
• 全文大小：1K

文摘

Effects of reducing agents on the textural properties and bulk/surface phase compositions of a precipitated iron-manganese catalyst were investigated by N₂-physisorption, X-ray photoelectron spectroscopy (XRD), M?ssbauer effect spectroscopy (MES), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy (LRS). Fischer-Tropsch synthesis (FTS) was performed in a slurry-phase continuously stirred tank reactor. The characterization results indicated that the hematite in the fresh catalyst was converted mainly to magnetite in H₂ atmosphere without the formation of intermediate metallic iron. Large amounts of Fe₃O₄ and small amounts of ¦Å?/em>-Fe_2.2C and ¦Ö-Fe_2.5C were formed after syngas pretreatment. In contrast, CO activation led to the formation of large amounts of ¦Ö-Fe_2.5C and carbonaceous species on the surface of magnetite. In the FTS reaction, the CO-activated catalyst presented the highest initial activity compared to the H₂ and syngas-reduced catalysts, and remained unchanged in the activity following the transformation of iron carbides to Fe₃O₄. Furthermore, the FTS activity of the H₂-reduced catalyst increased gradually accompanied with the conversion of magnetite to iron carbides. All of the results suggested that the formation of iron carbides (especially for ¦Ö-Fe_2.5C) on the surface layers provides probably the active sites for FTS, whereas the Fe₃O₄ formed plays a negligible role in the FTS activity.