Abstract:

The effects of reduction-carbonization temperature and reactor inlet CO concentration on the activity and selectivity of a self-developed industrial Fe-based Fischer-Tropsch synthesis catalyst (CNFT-1) were investigated under near-industrial conditions in a tail-gas recycle continuous stirred tank reactor. The results indicated that within the temperature range of 240℃ to 290℃, the hydrogenation activity of the catalyst improved with increasing reduction temperature. The selectivity toward light hydrocarbons (C₂—C₄) increased from 2.9% to 4.8%, while the selectivity for heavy hydrocarbons (C{}_{\mathrm{5}}^{+}) decreased from 94.9% to 92.0%, demonstrating a shift in hydrocarbon product distribution toward lighter components. Regarding catalytic activity, an optimal reduction temperature of 270℃ was identified. Both lower reduction temperature (240℃ and 250℃) and higher temperature (290℃) resulted in an inferior catalytic activity. The reduction process of the precipitated iron catalyst and Fischer-Tropsch reaction of syngas on the reduced active sites proceeded simultaneously. Maintaining a lower CO concentration (≤2.6%) at the reactor inlet yielded superior catalyst performance, characterized by high CO conversion (≥94.9%) and low byproduct selectivity (CO₂ + CH₄ selectivity within the range of 20.3%—22.0%).

Key words: catalyst, reduction, carbon monoxide, temperature, Fischer-Tropsch synthesis

摘要：

采用自主研发的工业级费托合成沉淀铁催化剂CNFT-1，在尾气循环搅拌釜反应器中近工业反应条件下考察了还原碳化温度和反应器入口CO浓度对催化剂活性和选择性的影响。结果表明，在240~290℃内，随着还原温度升高，还原后催化剂的加氢能力增强，费托合成产物中低碳烃（C₂~C₄）选择性从2.9%增加至4.8%，高碳烃（C{}_{\mathrm{5}}^{+}）选择性从94.9%降低至92.0%，烃类产物分布向轻组分方向移动。从催化剂活性来看，较适宜的还原温度为270℃，还原温度太低（240℃和250℃）或过高（290℃）得到的催化剂活性都偏低。费托合成沉淀铁催化剂的还原反应和合成气在已还原的活性位点上发生费托反应是同步进行的，还原时反应器入口保持较低的CO浓度（≤2.6%）将得到较高的催化剂活性（CO转化率≥94.9%）和较低的副产物选择性（CO₂与CH₄选择性之和在20.3%~22.0%内）。

关键词: 催化剂, 还原, 一氧化碳, 温度, 费托合成