A well-known observation in the Fe-catalyzed Fischer-Tropsch (FT) reaction is that Fe-carbide catalysts deactivate due to carbon deposition. In comparison, the influence of such carbon deposits on the product distribution has been less widely reported. The present work investigates the relationship between the kinetics of the FT reaction for a carburized Raney-Fe model catalyst and the composition of the catalytic surface with a focus on carbon deposits. The deposition of carbon during the ongoing FT reaction at low pressure decreases the FT activity and increases the CH₄ selectivity. Steady-state transient isotopic kinetic analysis (SSITKA) at low pressure shows that the buildup of C deposits affects fast CO conversion sites on the Fe-carbide surface, mainly responsible for CC coupling via a Langmuir-Hinshelwood mechanism, more than slow sites that mainly produce CH₄ via a Mars-Van Krevelen mechanism. Hindrance of migration of chain-growth monomers by C deposits decreases the amount of longer hydrocarbons. Nevertheless, SSITKA shows that C₂ products form faster, which is likely since their formation increasingly depends on monomers formed at proximate CO dissociation sites when the amount of carbon deposits increases. Carbon deposition can be suppressed and reversed by increasing the H₂/CO ratio at constant pressure or by increasing the total pressure at constant H₂/CO ratio. As such, the FT performance can be stabilized by operating at elevated pressure, even if initially the reaction was started at low pressure. Nevertheless, prolonged operation at low pressure leads to a less reactive character of the C deposits that cannot be removed anymore during high-pressure operation.

在铁催化的费-托 (FT) 反应中，众所周知的观察结果是碳化铁催化剂会因碳沉积而失活。相比之下，此类碳沉积物对产品分布的影响报道较少。目前的工作研究了渗碳 Raney-Fe 模型催化剂的 FT 反应动力学与催化表面组成之间的关系，重点是碳沉积物。在低压下进行的 FT 反应期间碳的沉积降低了 FT 活性并增加了 CH ₄选择性。低压下的稳态瞬态同位素动力学分析 (SSITKA) 表明，C 沉积物的积累会影响 Fe-碳化物表面上的快速 CO 转化位点，主要负责 C C 偶联通过Langmuir-Hinshelwood 机制，不仅仅是通过Mars-Van Krevelen 机制主要产生 CH _{4的缓慢站点。} C 沉积物对链增长单体迁移的阻碍减少了较长碳氢化合物的数量。尽管如此，SSITKA 表明C ₂产物形成得更快，这可能是因为当碳沉积量增加时，它们的形成越来越依赖于在邻近 CO 解离位点形成的单体。_{可以通过在恒定压力下增加 H 2} /CO 比率或通过在恒定 H ₂下增加总压力来抑制和逆转碳沉积/二氧化碳比率。因此，FT 性能可以通过在高压下操作来稳定，即使最初反应是在低压下开始的。然而，在低压下长时间运行会导致 C 沉积物的反应性降低，在高压运行期间无法再将其去除。