A thin-sheet Al-fiber@meso-Al 2 O 3 @Fe-Mn-K catalyst is developed for the mass/heat-transfer limited Fischer-Tropsch synthesis to lower olefins (FTO), delivering a high iron time yield of 206.9 mmol CO g 21
Fe s21 at 90% CO conversion with 40% selectivity to C 2 -C 4 olefins under optimal reaction conditions (3508C, 4.0 MPa, 10,000 mL/(gÁh)). A microfibrous structure consisting of 10 vol % 60-mm Al-fiber and 90 vol % voidage undergoes a steam-only-oxidation and calcination to create 0.6 mm mesoporous c-Al 2 O 3 shell along with the Al-fiber core. Active components of Fe and Mn as well as additives (K, Mg, or Zr) are then placed into the pore surface of c-Al 2 O 3 shell of the Al-fiber@meso-Al 2 O 3 composite by incipient wetness impregnation method. Neither Mg-modified nor Zr-modified structured catalyst yields better FTO results than K-modified one, because of their lower reducibility, poorer carbonization property, and fewer basicity. The favorable heat/mass-transfer characteristics of this new approach are also discussed.