Assessment of an integrated adsorption-regenerative catalytic oxidation process for the harnessing of lean methane emissions

Lean methane emissions constitute an important environmental problem due to the high global warming potential of methane compared to carbon dioxide. Typical emissions (e.g., coal mines, landfills, treatment plants, etc.) have high gas flow rate and low concentration, making its harnessing a challenging task. For this reason, an integrated adsorption/desorption and regenerative catalytic oxidation process has been proposed and designed for the treatment of an emission of 4.5 Nm3/s containing 0.20 vol% methane. To accomplish this task, methane adsorption/desorption operation has been firstly studied experimentally in a bench-scale fixed bed (adsorbent bed of 0.145 m length and 0.060 m diameter) loaded with 3 mm pellets of an activated carbon adsorbent. The information gathered on the equilibrium and kinetics, at different methane concentrations (0.20-0.50 vol%) and space velocities (WHSV 3.0-15 mol/kg h), has been used to fit a dynamic model. Then, a regenerative catalytic oxidizer has been designed and its performance studied by means of simulations. Special attention has been paid to assessing the influence of the integration of the regenerative catalytic oxidizer with the adsorption/desorption step.