Simultaneous carbon dioxide and steam reforming of methane to syngas over NiO- CaO catalyst

Abstract

Steam reforming, CO₂ reforming, and simultaneous steam and CO₂ reforming of methane to CO and H₂ over NiO-CaO catalyst (without any prereduction treatment) at different temperatures (700-850¯C) and space velocities (5000-70000 cm³. g^-1.h^-1) are investigated. The catalyst is characterized by XRD, XPS, and temperature-programmed reduction (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 is found to be very fast. However, when the CO₂ reforming is carried out simultaneously with the steam reforming, the coke deposition on the catalyst is drastically reduced. By the simultaneous CO₂ and steam reforming (at ≥800 °C and space velocity of about 20000-30000 cm³. g^-1.h^-1), methane can be converted almost completely to syngas with 100% selectivity for both CO and H₂. The H₂/CO ratio in products can be varied between 1.5 and 2.5 quite conveniently by manipulating the relative concentration of steam and CO₂ in the feed.