In this work, the authors design, fabricate, and evaluate three prototype ceramic microchannel reactor architectures with two-dimensional complex flow configurations for coupling methanol steam reforming with methanol combustion/partial oxidation. These prototypes were evaluated for the autothermal hydrogen production from methanol in order to investigate the influence of individual process flow rates and radial distribution schemes upon thermal gradients and overall system performance in the absence of any external insulation. Results demonstrate that, in the case of low thermal conductivity ceramic substrates, appropriate selection of two-dimensional radial distribution patterns enables the tailoring of one- and three-dimensional thermal gradients for enhancing self-insulating qualities of the microchannel reactor as well as enhancing overall hydrogen yields.

This paper details a combination of experimental and theoretical design analyses of a cartridge-based microchannel reformer system capable of integrating two or three separate reforming processes (reactant preheating, methanol steam reforming, and methanol combustion for autothermal operation) within a single monolithic device in a two-dimensional or radially layered distribution pattern. This system employs a ceramic microchannel cartridge with catalyst configurations tailored to enable stable autothermal operation over a broad range of reforming and combustion flow rates. Operation of the 25-channel prototype system coupling methanol combustion in air (13 mol % CH3OH and 17.3 mol % O2) with steam reforming of a dilute (2.6 mol %) methanol–water mixture at combustion and reforming overall flow rates of 300 standard cubic centimeters per minute (sccm) [gas hourly space velocity (GHSV) of 19 200 h–1] and 1800 sccm (GHSV of 14 400 h–1) achieved steam reforming hydrogen yields of ∼85%, corresponding to an overall hydrogen yield of 53%. When the outer layer of microchannels is employed for preheating of the reforming stream, the overall hydrogen yield was improved to 57%. A three-dimensional simulation of the microchannel reformer was constructed and validated through comparison to experimental data and then employed to predict the reformer performance using a concentrated (25 mol % CH3OH and 75 mol % H2O) steam reforming feed. Design simulations predict that hydrogen yields of ∼80% are achievable using the cartridge-based ceramic microchannel reformer.