浆态床F-T合成反应中反应参数对Fe/Cu/K/SiO_2催化剂性能的影响

Effect of Reaction Parameters on Catalytic Performance of Fe/Cu/K/SiO_2 for Slurry Phase Fischer-Tropsch Synthesis

用喷雾干燥法制备了微球状Fe/Cu/K/SiO2催化剂,并在不同的反应条件下对其在浆态床F-T合成反应中的催化性能进行了评价.结果表明,反应温度和原料气H2/CO比的调变对催化剂运行稳定性的影响较大,反应初始阶段加入的液体石蜡介质对催化剂运行稳定性的影响不大.原料气空速的增加可有效地提高反应的总烃时空产率,但同时CO转化率会明显降低,且重质烃选择性下降;低H2/CO比的原料气有利于在保持合适的转化率的同时提高重质烃的选择性,并可明显提高总烃的时空产率;提高系统压力可增大催化剂的催化活性,改善重质烃的选择性;而提高反应温度尽管可明显提高催化剂活性,但同时也会促进WGS反应的发生,降低重质烃的选择性.因此,浆态床F-T合成反应中操作参数的适当调变可使催化剂活性、产物烃分布和烃产率得到有效优化,最大限度地获得目的产物.

Fischer-Tropsch synthesis over the spray-dried Fe/Cu/K/SiO2 catalyst was performed in a slurry reactor under different reaction conditions for about 1 400 h . The results indicated that the changes of the reaction conditions, especially the reaction temperature and H2/CO feed ratio had strong effects on the catalytic performance of the Fe/Cu/K/SiO2 catalyst. The addition of liquid paraffin medium had no distinct influence on the catalyst stability. An increase in the space velocity of the feed gas could effectively increase the hydrocarbon productivity and suppress the water-gas-shih （WGS） reaction, but evidently decrease the CO conversion and the selectivity for heavy hydrocarbons. Increasing the H2/CO feed ratio notably increased the H2 partial pressure in the reaction system, suppressed the WGS reaction and raised the CO conversion. However, the higher hydrocarbon productivity and selectivity for heavy hydrocarbon and olefin products could be obtained at a lower H2/CO feed ratio. The increase in the system pressure apparently improved the activity and heavy hydrocarbon selectivity of the catalyst. The reaction could be markedly accelerated by increasing the reaction temperature, while the heavy hydrocarbon selectivity decreased because of the occurrence of the WGS reaction.