SIMULTANEOUS CARBON-DIOXIDE AND STEAM REFORMING OF METHANE TO SYNGAS OVER NIO-CAO CATALYST

Steam reforming, CO2 reforming, and simultaneous steam and CO2 reformi ng of methane to CO and H-2 over NiO-CaO catalyst (without any preredu ction treatment) at different temperatures (700-850 degrees C) and spa ce velocities (5000-70000 cm(3) . g(-1). h(-1)) are investigated. The catalyst is characterized by XRD, XPS, and temperature-programmed redu ction (TPR). The catalyst showed high activity/selectivity in both the steam and CO2 reforming reactions and the simultaneous steam and CO2 reforming. In the CO2 reforming, the coke deposition on the catalyst i s found to be very fast. However, when the CO2 reforming is carried ou t simultaneously with the steam reforming, the coke deposition on the catalyst is drastically reduced. By the simultaneous CO2 and steam ref orming (at greater than or equal to 800 degrees C and space velocity o f about 20000-30000 cm(3) . g(-1). h(-1)), methane can be converted al most completely to syngas with 100% selectivity for both CO and H-2. T he H-2/CO ratio in products can be varied between 1.5 and 2.5 quite co nveniently by manipulating the relative concentration of steam and CO2 in the feed.