Comparative evaluation of autothermal reforming of biogas into synthesis gas over bimetallic NiRe/Al2O3 catalyst in fixed-bed and coated-wall microreactors: A computational study

Autothermal reforming reaction of biogas over a novel NiRe/Al2O3 catalyst in a coated-wall microreactor was numerically investigated and compared with that in a fixed-bed microreactor having the same catalyst loading. The effects of inlet concentrations of O2 and H2O as well as temperature on the reaction effectiveness within both microreactors were, for the first time, assessed to determine an optimal condition, which yielded complete CH4 and CO2 conversions, H2/CO ratio of around one and minimal hot spot formation. Such an optimal condition was then used to study the effect of inlet reactant Reynolds number on the reactor performance. Higher CH4 and CO2 conversions, lower H2O production and less hot spot formation were noted in the case of the coated-wall microreactor. The optimal condition occurred at CH4:CO2:O2:H2O ratio of 39:26:30:5% (v/v) and inlet temperature of 740 °C. The performance of the coated-wall microreactor was superior to that of the fixed-bed microreactor in all cases.