CO2 reforming of methane to synthesis gas over sol-gel-made Co/γ-Al2O3 catalysts from organometallic precursors

Three cobalt-based catalysts with the same cobalt content (10 wt.%) were prepared by conventional impregnation of commercial gamma -Al2O3 support (CoAlCO-IM) sol-gel-made gamma -Al2O3 (CoAlSG-IM) and direct sol-gel processing from organometallic compounds (CoAlSG), respectively. At 750 degreesC, all three catalysts had the same catalytic activity. However, CoAlSG catalyst showed relatively low catalytic activity at low reaction temperatures (550-650 degreesC) and high space velocity, due to the formation of CoAl2O4. It had the best coking resistivity with the average coking rate of 0.0025 g(carbon) g(cat.)(-1) h(-1). Fast and heavy coke deposition occurred on CoAlCO-IM catalyst, with an average coking rate of 0.11 g(carbon) g(cat.)(-1) h(-1). The Lifetime of CoAlSG catalyst was 24 times longer than that of CoAlCO-IM catalyst, under thermodynamically severe reaction conditions (CO2/CH4=0.88, 700 degreesC). Compared to CoAlCO-IM catalyst, CoAlSG possesses smaller metallic Co particles, richer surface OH species and stronger metal-support interaction. All of these properties may benefit the inhibition of coke formation. (C) 2001 Elsevier Science B.V. All rights reserved.