A set of alumina supported cobalt catalysts was prepared, varying the synthesis method and formulation to produce a range of cobalt particle sizes. A combination of degree of reduction (DOR) measurements and H₂ chemisorption was used to calculate the cobalt particle sizes on the fresh catalyst samples (5–19 nm). The catalysts were pre-reduced and encapsulated in wax prior to testing for Fischer-Tropsch (FT) activity in a continuous-stirred tank reactor (CSTR) system for between 500 and 6000 h on-line. The catalysts all demonstrated rapid deactivation over the first 200 h of FT testing, with the catalysts with the highest initial activity deactivating most rapidly. Characterisation of the discharged catalysts samples using XRD, TEM and H₂ chemisorption indicated that the cobalt particles had undergone a sintering process consistent with an Ostwald ripening mechanism. Catalyst stability in CSTR testing can be enhanced by the presence of large cobalt particles (>20 nm).

制备了一组氧化铝负载的钴催化剂，改变了合成方法和配方以产生一定范围的钴粒度。结合使用还原度（DOR）测量和H ₂化学吸附来计算新鲜催化剂样品（5–19 nm）上钴的粒径。在连续搅拌釜反应器（CSTR）系统中在线进行500至6000小时测试费-托（FT）活性之前，将催化剂预还原并包封在蜡中。在FT测试的前200个小时中，所有催化剂均表现出快速失活，而具有最高初始活性的催化剂则失活最快。使用XRD，TEM和H ₂表征排放的催化剂样品化学吸附表明，钴颗粒已经经历了与奥斯特瓦尔德熟化机制一致的烧结过程。大钴颗粒（> 20 nm）的存在可以增强CSTR测试中的催化剂稳定性。