Titania-Supported Bimetallic Catalysts Combined with HZSM-5 for Fischer−Tropsch Synthesis

Fischer−Tropsch synthesis was studied in a fixed-bed reactor over single-metal and bimetallic alloy catalysts, selected from Co, Ni, and Fe, supported on TiO 2 at a total metal loading of 10 wt %. The catalysts, prepared by incipient wetness impregnation using nitrate precursors, were tested as is and in combination with a HZSM-5 zeolite. The test conditions were 1 MPa, 250 °C, H 2 /CO = 1, and weight hourly space velocity (WHSV) = 0.77 h - 1 . Alloying of metals resulted in a significant enhancement in CO conversion without an increase in methane selectivity. A 50:50 weight ratio Co−Ni catalyst physically mixed with HZSM-5 (5% Co−5% Ni/TiO 2 + HZSM-5) gave the highest CO conversion (45.2%) at the conditions tested. This compares to conversion of 8.9% and 10.5% with Co-only and Ni-only catalysts, respectively. Mixing the Co−Ni catalyst with HZSM-5 resulted in a significant reduction in methane selectivity and a significant increase in C 4 + selectivity. The aromatic fraction increased from 1.5 to 8.1 wt %, the C 2 + olefins were nearly eliminated, and i -C 4 H 10 increased from 2.3 to 58.5 wt % in the C 4 fraction.