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

Abstract

Three cobalt-based catalysts with the same cobalt content (10 wt.%) were prepared by conventional impregnation of commercial γ-Al2O3 support (CoAlCO-IM), sol-gel-made γ-Al2O3 (CoAlSG-IM) and direct sol-gel processing from organometallic compounds (CoAlSG), respectively. At 750 °C, all three catalysts had the same catalytic activity. However, CoAlSG catalyst showed relatively low catalytic activity at low reaction temperatures (550-650 °C) 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.)-1h-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 °C). 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.