Total methanation of syngas to synthetic natural gas over Ni catalyst in a micro-channel reactor

Methanation reaction from syngas to synthetic natural gas (SNG) has been successfully implemented over Ni catalyst in a micro-channel reactor with high conversion and selectivity in milliseconds contact time. A new method called improved thermal spray to manufacture the metal-ceramics complex substrate as catalyst support was presented. The substrate demonstrated dual functions, i.e., the superior heat conduction as metal and stable catalyst coating on it as ceramics (e. g., Al2O3). The experiments verified that the fall-off proportion of the catalyst can be neglected after the plates experienced methanation reaction and strong vibration in ultrasonic cleaner. Meanwhile, the catalyst coatings on the walls of micro-channel reactor showed high activity and stability, having the excellent catalytic performance for methanation reaction in micro-channel reactors and the reliability in long-term use as well. At the temperature of 550 degrees C and the pressure of 30 atm, CO conversion and CH4 selectivity can remain above 98% and 92%, respectively, at a high GHSV of 71,000 h (1), where the corresponding residence time is only about 50 ms. Extensive characterizations of these Ni catalyst plates were also made to get a better understanding of the catalytic performance. The results of XRD, SEM, TEM and TPR characterizations demonstrated that Ni catalysts prepared in this work did not show any sign of deactivation after being used in the micro-channel system. It is expected that the methanation reactor technique based on the metal-ceramics complex substrate as the catalyst support in (micro-)channel reactors would open opportunities for the reliable engineering applications of either distributed or mass production of SNG from syngas. (C) 2011 Elsevier Ltd. All rights reserved.