Sasol Technology R&D, Sasolburg 1947, South Africa.
J Chromatogr A. 2011 May 27;1218(21):3173-9. doi: 10.1016/j.chroma.2010.10.009. Epub 2010 Oct 24.
In oligomerisation products of High Temperature Fischer-Tropsch (HTFT) derived light alkenes using a solid phosphoric acid (SPA) catalyst, the presence of cyclics was presumed although their occurrence could not be explained by the generally accepted oligomerisation mechanism. Notwithstanding the use of GC×GC-TOFMS, the cyclic alkanes could not be differentiated from the alkenes. On the one hand, compounds co-eluted in GC×GC and, on the other hand, MS cannot distinguish between these classes because of identical molecular masses and very similar mass fragmentation patterns. An LC pre-fractionation procedure utilising a silver-modified column was developed to separate the saturates from the unsaturates. Using this approach we were able, for the first time, to confirm the presence of cyclics, probably resulting from secondary reactions, in HTFT oligomerisation products. The occurrence of cyclics can be an indication of the beginning of carbonaceous deposit formation that could eventually lead to catalyst deactivation.
在使用固体磷酸（SPA）催化剂的高温费托（HTFT）衍生轻烯烃的低聚产物中，尽管它们的出现不能用普遍接受的低聚机理来解释，但推测存在环状物。尽管使用了 GC×GC-TOFMS，但是仍然无法将环状烷烃与烯烃区分开来。一方面，化合物在 GC×GC 中共同洗脱，另一方面，由于分子量相同且质量碎裂模式非常相似，MS 无法区分这两类物质。开发了一种利用银修饰柱的 LC 预分级程序，将饱和物与不饱和物分离。通过这种方法，我们首次能够确认 HTFT 低聚产物中存在可能由次级反应产生的环状物。环状物的存在可能表明碳质沉积物形成的开始，最终可能导致催化剂失活。
