Fischer–Tropsch (FT) reactors, e.g. fixed-beds, are usually operated in the steady state. The accumulation of long-chain liquid hydrocarbons (waxes) in the catalyst's pores during the start-up of a reactor then frequently leads to internal mass transfer limitations, and hence to a decrease of the effective reaction rate. An alternating FT/hydrogenolysis process is proposed to minimize pore diffusion limitations and to enhance the mean reaction rate. This transient process was realized by switching between a pore filling FTS sequence with only partially liquid-filled pores (at least on average) and a pore draining hydrogenolysis sequence, realized by a switch from syngas (H₂, CO) to a H₂-rich but CO-free feed gas. The preferential filling of the catalyst particles with higher C₂₁₊-hydrocarbons during FTS and the subsequent cracking to short-chain hydrocarbons by hydrogenolysis limit the production of waxes. The influence of the filling and draining time on the process enhancement as well as on the selectivity towards liquid fuels (C₅–C₂₀-fraction) was experimentally investigated, indicating an increase of the mean reaction rate by 20%; further improvements are outlined based on theoretical considerations.

中文翻译：

---

费托合成通过氢解作用定期排空液体填充的催化剂

费托反应堆（FT）反应器，例如固定床，通常在稳态下运行。然后，在反应器启动期间，长链液态烃（蜡）在催化剂孔中的积累经常导致内部传质的局限性，从而导致有效反应速率的降低。提出了交替的FT /氢解工艺以最小化孔扩散限制并提高平均反应速率。通过在仅具有部分填充液体的孔（至少平均）的填充孔的FTS序列和从合成气（H ₂，CO）转换为H _2的排孔氢解序列之间进行切换，可以实现此过渡过程富含但不含一氧化碳的原料气。在FTS中用较高的C ₂₁₊烃优先填充催化剂颗粒以及随后通过氢解裂_化成短链烃限制了蜡的生产。实验研究了填充和排出时间对工艺增强以及对液体燃料的选择性（C ₅ -C ₂₀馏分）的影响，表明平均反应速率提高了20％。基于理论上的考虑，概述了进一步的改进。