Middle distillates production via Fischer–Tropsch synthesis with integrated upgrading under supercritical conditions

A vertically aligned fixed‐bed reactor system with a cascade of three sequential catalyst beds has been used to incorporate Fischer–Tropsch synthesis (FTS) in the first bed, oligomerization (O) in the second bed, and hydrocracking/isomerization (HC or C) in the third bed (FTOC). Compared to gas phase FTS (GP‐FT) alone, gas phase FTS with the subsequent upgrading beds (GP‐FTOC) is demonstrated to result in a reduction in the olefin selectivity, a reduction in the C 26+ selectivity, and a marked enhancement in the production of branched paraffins and aromatics. Utilization of supercritical hexane as the reaction medium in supercritical FTS (SC‐FT) and supercritical phase FTOC (SC‐FTOC) resulted in a significant reduction in both CH 4 selectivity and CO 2 selectivity. Interestingly, significant amounts of aldehydes and cyclo‐paraffins were collected in SC‐FT and in SC‐FTOC, respectively, while not being observed in traditional gas phase operation (both GP‐FT and GP‐FTOC). © 2014 American Institute of Chemical Engineers AIChE J , 60: 2573–2583, 2014