Catalytic combustion of sulphur-containing methane lean emissions in a reverse-flow reactor with integrated adsorption

Lean methane emissions (0.15-0.5% CH4) often contain low concentrations of sulphur compounds (e.g. H2S). Regenerative catalytic oxidation is an efficient process for methane removal and upgrading of these streams, but the presence of sulphur compounds deactivates typical combustion catalysts. We propose in this work a new strategy for overcoming this problem, by using a reverse flow reactor provided with integrated adsorption beds. Therefore, it is possible to operate autothermically with low methane concentrations, as well as effectively separate the sulphur compounds before reaching catalytic bed. The working principle of this device has been experimentally demonstrated in a bench-scale reactor working at conditions typical for industrial emissions (GHSV = 1146 h−1, 4300 ppm CH4, 100-500 ppm H2S). It has been found that molecular sieve 5A is a suitable adsorbent for this device. The influence of the main reverse flow reactor variables, switching time (200-400 s) and methane feed concentration (4000-4500 ppm), on the performance of the process has been studied. The integrated adsorption performs better at switching time 400 s, while methane concentration has negligible influence, provided that the reactor is maintained ignited.