Operating the Fischer–Tropsch synthesis at high conversion would allow a simpler once-through configuration to be used for small-scale biomass and waste to liquid. The effect of high conversion, and consequently high partial pressure of H₂O and low partial pressures of CO and H₂, on the stability of nano-sized cobalt crystallites in Pt–Co/Al₂O₃ is investigated_. Whilst hydrothermal environments are commonly investigated for deactivation, this is typically done under ‘simulated’ high conversion (low conversion, high partial pressure of water) conditions. Thus, the current study will present the differences between real high conversion and ‘simulated’ high conversion and attempt to decouple the deactivation mechanisms associated with both cases. At conversion levels higher than X_CO = 70% for this study (T = 220 °C, p = 20 bar, feed of H₂ : CO : N₂ = 2 : 1 : 3), sintering, cobalt aluminate formation and cobalt oxidation led to rapid deactivation. ‘Simulated’ high conversion is found to cause less cobalt aluminate formation, but more carbon deposition. At very high conversion (X_CO > 97%) enhanced reversible deactivation was exhibited due to oxidation and re-reduction of cobalt (shown via in situ magnetometer). A ‘maximum’ conversion seems to exist for a specific cobalt crystallite size caused by its oxidation.

中文翻译：

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解耦以高转化率和“模拟”高转化率运行的钴费-托催化剂的失活机理

费-托合成的高转化率运行将允许使用简单的直通式配置来处理小规模的生物质和废物到液体。高的转化率，和H随后高局部压力的作用₂ O和CO和H的低分压₂上的纳米尺寸的钴微晶的在铂-钴/ Al的稳定性，₂ ö ₃进行了研究_。虽然通常研究热液环境来失活，但这通常是在“模拟”高转化率（低转化率，高水分压）条件下完成的。因此，当前的研究将提出真实的高转化率与“模拟的”高转化率之间的差异，并试图解耦与两种情况相关的停用机制。在此研究中，转化率高于X _CO = 70％（T = 220°C，p = 20 bar，H ₂  ：CO：N ₂进料＝ 2∶1∶3），烧结，铝酸钴的形成和钴的氧化导致快速失活。发现“模拟”高转化率导致铝酸钴生成量减少，但碳沉积量增加。在非常高的转化率下（X _CO > 97％），由于钴的氧化和再还原（通过原位磁力计显示），增强了可逆失活。对于由其氧化引起的特定钴微晶尺寸而言，似乎存在“最大”转化率。