Autothermal reforming of methane for syngas production in a novel ceramic microchannel reactor

Abstract

Ceramic microchannel reactors offer significant advantages to current microreactor technology due to the ability to operate at high temperatures and harsh chemical environments while using relatively inexpensive materials and manufacturing processes. Previous research on a novel ceramic microchannel reactor demonstrated a maximum heat exchanger effectiveness of 88% under inert flow conditions and 100% methane conversion at a gas hourly space velocity (GHSV) of 15,000 1/hr under steam methane reforming (SMR) conditions. This work focuses on widening reactor operating conditions by exploring autothermal reforming and catalytic partial oxidation (CPOX) of methane. Effects of both endothermic SMR and exothermic CPOX will be explored on product composition as well as reactor temperatures. Furthermore, reactive side flow rates are increased beyond previous tests, to a maximum GHSV of 75,000 1/hr. Additionally, a computational fluid dynamics (CFD) model is implemented in ANSYS Fluent, which combines fluid flow, heat transfer, and a 48 step heterogeneous chemical mechanism into a three-dimensional model. Investigation into reactor testing with the CFD model allows not only for accurate prediction of reactor performance, but gives insight into the effects of exothermic and endothermic chemistry inside the reactor. Experimental results indicate that the presence of O2 in the fuel stream dominates reactor exhaust temperatures, although varying concentrations of O2 and H2O are shown to influence product composition. The microchannel reactor showed no signs of thermal stress, despite operating at stoichiometric CPOX conditions. Autothermal reforming demonstrated promising results, achieving 90% methane conversion at a GHSV of 75,000 1/hr for a S/C ratio of 2.5 and O/C ratio of 1.