CO sub(2) recycling by reaction with renewably-generated hydrogen

• Published in: International journal of greenhouse gas control Vol. 4; no. 1; pp. 44 - 50
• Main Authors: Hoekman, SKent, Broch, Amber, Robbins, Curtis, Purcell, Richard
• Format: Journal Article
• Language: English
• Published: 01.01.2010
• ISSN: 1750-5836
• DOI: 10.1016/j.ijggc.2009.09.012

A laboratory-scale reactor system was built and operated to demonstrate the feasibility of catalytically reacting carbon dioxide (CO sub(2)) with renewably-generated hydrogen (H sub(2)) to produce methane (CH sub(4)) according to the Sabatier reaction: CO sub(2) + 4H sub(2) --> CH sub(4) + 2H sub(2)O. A cylindrical reaction vessel packed with a commercial methanation catalyst (Haldor Topsoee PK-7R) was used. Renewable H sub(2) produced by electrolysis of water (from solar- and wind-generated electricity) was fed into the reactor along with a custom blend of 2% CO sub(2) in N sub(2), meant to represent a synthetic exhaust mixture. Reaction conditions of temperature, flow rates, and gas mixing ratios were varied to determine optimum performance. The extent of reaction was monitored by real-time measurement of CO sub(2) and CH sub(4). Maximum conversion of CO sub(2) occurred at 300-350 degree C. Approximately 60% conversion of CO sub(2) was realized at a space velocity of about 10,000 h super(-1) with a molar ratio of H sub(2)/CO sub(2) of 4/1. Somewhat higher total CO sub(2) conversion was possible by increasing the H sub(2)/CO sub(2) ratio, but the most efficient use of available H sub(2) occurs at a lower H sub(2)/CO sub(2) ratio.