A cold start-up method with combining chemical-looping combustion and catalytic combustion for a methanol reformer

Abstract

The cold start-up time is crucial for an on-line methanol reformer. The light-off temperatures of methanol, H2 and CO catalytic combustion, the light-off temperatures of methanol decomposition and methanol steam reforming, and the light-off temperatures reducing oxidative copper-based catalysts/oxygen carriers (CCOCs) with methanol, H2 and CO were measured. According to these results, a novel cold start-up method with combining chemical-looping combustion and catalytic combustion (CLC&CC) over CCOCs was proposed in this paper. Firstly, the air is introduced into the reformer and the reformer is heated from the ambient temperature to the light-off temperatures of methanol catalytic combustion with the oxidation reaction heat of the reductive CCOCs, here a part of reductive CCOCs is transformed to oxidative CCOCs. Then, air and methanol are introduced into the reformer and the reformer is further heated to the required temperature with the heat of methanol catalytic combustion and the reduction heat of oxidative CCOCs. By decreasing the end temperature of the air oxidation step as low as its light-off temperature, the oxidation amount of reductive CCOCs, that is, the metallic Cu is greatly decreased, thus, the influence of a cold start-up on CCOCs is limited. Through 200 times cold start-up based on this method, the methanol steam reforming conversion was kept near 100%, while the cold start-up time decreased from 65 s to 62 s. This was in accordance with the characterization results that the dispersion of active substance of metallic Cu in CCOCs was significantly improved through the cold start-up.