Figure 7. Methanol mole fraction contour maps in the microchannel methanol steam reformer reactor that comprises a plurality of process and heat exchange microchannels.
The hydrogen mole fraction contour maps are illustrated in Figure 8 for the microchannel reactor that comprises a plurality of process and heat exchange microchannels. An interfacial layer containing one or more active metals or alloys can be deposited on the engineered shape to provide catalytic functionality. An intermediate interfacial layer may be deposited between the metal substrate and the catalyst containing interfacial layer to enhance structural integrity of thus formed outer catalyst containing interfacial layer. An important factor that commonly used to describe reactor reforming capacity of a tubular reactor is the heat transfer rate. Surface heat flux is referred to as the rate of heat energy transfer through the reactor walls for a given tube surface area, while the volumetric heat flux is referred to the rate of heat energy transfer through the reactor walls for a given tube interior volume. Smaller diameter catalytic reactors can offer several advantages, for example improving heat transfer from external heat source to reaction mixture in the tube, enhancing tube life-time by reducing thermal gradients, reducing metal material use, and being applicable for compact steam reformer systems. To achieve similar production capacity as steam methanol reformer plants, small diameter tubular reactors require a plurality of tubing components in series and much higher space velocity. It is challenging for direct catalyst coating on tubing wall to achieve high methanol conversion due to limitation of catalytic surface area and coating delamination at high operating temperature and large temperature gradient across tube wall. The catalyst inserts, structured monoliths can be configured with a single layer metal sheet stamped with a plurality of peaks and grooves. Peaks on metal sheets serve as geometry support to prevent structure deformation and create multiples of open channels for reactant gas flow, while grooves on metal sheets provide open windows for gas communications between each layer of the monoliths. The present design allows for the efficient use of metal foil comprising plurality of designed patterns on its surface, rolled into a multi-layer spiral shaped like a compact foil cylinder and catalyzed to serve as a catalyst insert in a high aspect ratio reactor. The designed patterns establish open gas channels between each of the rolled layers. This unique geometry accelerates gas mixing and the large surface area of metal foil provides a high catalytic active surface area.