Iron-catalyzed conversion of coal/biomass-derived syngas directly to lower olefins through Fischer–Tropsch synthesis (i.e., FTO) is a sustainable and short-flow process. Herein, effects of Mn and K promoter loadings on FTO performance over the Fe-based catalyst supported on the promoter-adjustable carbon nanotubes (Fe/Mn_xK_y-CNTs) are systematically studied. Several Mn_xK_y-CNTs are prepared by the treatment of CNTs using aqueous KMnO₄ solution via a redox reaction, where promoter loadings are tailored by changing the aqueous KMnO₄ solution concentration and water amount for sample washing. FTO performance of these catalysts suggests that the increase in Mn and K loadings shows the enhanced lower olefins selectivity but suppressed activity. The resultant Fe/Mn_16.5K_1.2-CNTs exhibit the highest lower olefins yield. Further increasing K promoter content leads to slightly enhanced activity to lower olefins but dramatically suppressed CH₄ formation and enhanced chain growth. Moreover, appropriate precarburization temperature can facilitate the activity and selectivity toward lower olefins formation.

中文翻译：

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定制Fe / MnK-CNTs复合催化剂用于费托合成气合成低级烯烃

通过费-托合成法（即FTO）将铁/煤/生物质合成气直接铁催化转化为低级烯烃是一种可持续的短流程工艺。在本文中，系统地研究了Mn和K助催化剂负载量对负载在促进剂可调节碳纳米管（Fe / Mn _x K _y -CNTs）上的Fe基催化剂的FTO性能的影响。通过使用KMnO ₄水溶液通过氧化还原反应处理CNT来制备几种Mn _x K _y -CNT ，其中通过改变KMnO ₄水溶液来定制促进剂的负载量溶液浓度和水量，用于样品洗涤。这些催化剂的FTO性能表明，Mn和K负载量的增加显示出较低的烯烃选择性增强，但活性降低。所得的Fe / Mn _16.5 K _1.2 -CNT显示出最高的较低烯烃产率。钾助催化剂含量的进一步增加导致对低级烯烃的活性略有增强，但大大抑制了CH _4的形成并增强了链的生长。而且，适当的预碳化温度可以促进对低级烯烃形成的活性和选择性。