Comparative numerical evaluation of autothermal biogas reforming in conventional and split-and-recombine microreactors

Abstract

A new microreactor design featuring embedded passive mixing elements was tested as a means to enhance autothermal reforming reaction of biogas over a novel ReNi/γ-Al2O3 catalyst. To determine an optimal condition that would result in completely converted biogas with H2/CO product ratio of around one and minimal hot spot formation inside the reactor, use of various inlet O2 and H2O concentrations and inlet temperatures were numerically investigated. The influence of inlet reactant velocity on the reactor effectiveness was then studied at the optimal condition. Performance of a straight-channel microreactor was also studied and compared with that of the novel microreactor. The O2:H2O:CO2:CH4 ratio of 25:5:28:42% (v/v) and inlet temperature of 730 °C were noted as the optimal condition for the novel microreactor. Complete biogas conversion over a wider range of inlet Reynolds number, lower required catalyst loading to achieve the desired reactor performance, higher H2 and CO selectivities and reduced hot spot formation were noted as the advantages of the novel microreactor.