极性溶剂相费托合成的产物分布特征

Product Distribution of Fischer-Tropsch Synthesis in Polar Liquids

在间歇反应釜中研究了极性溶剂中工业铁基催化剂上费托合成的产物分布特点,考察了不同极性溶剂(聚乙二醇400和600,1,4-丁二醇,乙二醇)和非极性溶剂正辛烷,反应条件(温度,进料H2/CO比,反应时间)和操作模式(间歇,半连续)对产物选择性和链增长因子α的影响.结果表明,在所考察的条件下,产物中α-烯烃(除了乙烯)的选择性几乎不随碳数变化,这完全不同于采用非极性介质的传统费托合成,对于高选择性地生产线性α-烯烃具有重要的意义.通过优化操作条件,产物中α-烯烃的平均含量可超过70%.产物分布大多偏离理想的ASF分布,无法用烯烃再吸附理论来解释.链增长因子α均大于0.85,表明极性介质有利于长链烃的生成.

The effect of using polar liquid as the reaction medium for Fischer-Tropsch synthesis on the product distribution was studied. The experiments were performed with an industrial iron-based catalyst in a batch autoclave reactor with different liquid phases （polyethylene glycol 400, polyethylene glycol 600, 1,4-butanediol, and glycol）. The reaction conditions were temperature of 200–240 ？C, initial H2/CO molar ratios of 1.00–2.03, catalyst particle sizes of 20–40 mesh and 150 mesh, and reaction time of 24–144 h. The α-olefin selectivity was significantly increased to more than 70% and was almost independent of carbon number with all the polar liquids. Most of the hydrocarbon distribution were not of the ideal Anderson-Schulz-Flory pattern and could not be explained by the mechanism of olefin readsorption and secondary reactions. The chain growth probability α was larger than 0.85 for all conditions, and it was slightly influenced by changes of reaction conditions, liquid, and reaction time. There was product separation during reaction in this catalytic system, which meant that it did not have the problem of separating the catalyst from the wax product that traditional slurry reactors have. The result suggested new opportunities for the selective production of linear α-olefins and for mechanistic investigations of Fischer-Tropsch synthesis.