CO 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, S. Kent, Broch, Amber, Robbins, Curtis, Purcell, Richard
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 2010
• Subjects: CO 2 recycling; Greenhouse gas; Methanation; Renewable hydrogen; Sabatier reaction; Methanation; Renewable hydrogen; Greenhouse gas; Sabatier reaction; CO 2 recycling
• ISSN: 1750-5836; 1878-0148
• 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 2) with renewably-generated hydrogen (H 2) to produce methane (CH 4) according to the Sabatier reaction: CO 2 + 4H 2 → CH 4 + 2H 2O. A cylindrical reaction vessel packed with a commercial methanation catalyst (Haldor Topsøe PK-7R) was used. Renewable H 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 2 in N 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 2 and CH 4. Maximum conversion of CO 2 occurred at 300–350 °C. Approximately 60% conversion of CO 2 was realized at a space velocity of about 10,000 h −1 with a molar ratio of H 2/CO 2 of 4/1. Somewhat higher total CO 2 conversion was possible by increasing the H 2/CO 2 ratio, but the most efficient use of available H 2 occurs at a lower H 2/CO 2 ratio.