Electrophoretic coating for steam methane micro‐reformer: Optimum voltage and time, channel design, and substrate type

چکیده مقاله

Following our previous simulation study, in this study manufacturing of previously simulated micro-reformer was carried out in order to study intensifying steam methane reforming. SUS 310 was selected as the base material and a copper gasket was used for sealing. Because of simplicity and being straightforward, the electrophoretic deposition method was used for the first time to coat a commercial Nickel-based reforming catalyst onto reaction plates. All reaction plates had the dimensions of 21 × 20 mm and at most 3 mm depth. S310 was used for anode and S304 for cathode. Reduction of catalyst was performed at 650°C. Five cm quartz packing was used to preheat feed before entering the micro-reformer. In the first part, after investigating important variables of voltage and coating time in the range of 1 to 4 minutes and 100 to 140 V, optimum conditions were found to be 120 V and 1.5 minute, respectively, which gave 5.1 mg/cm2 surface density. At optimum condition, micro-reformer had better performance than packed-bed reactor even at low weight hourly space velocities. In the second part of the study, three channel designs, that is, parallel, splitting-jointing, and pin-hole were designed, manufactured, and mounted into the micro-reformer. Based on specific methane conversion, splitting-jointing had marginally better performance than parallel channels. This finding was contrary to the simulation results. This difference originates from two reasons: (a) monolayer assumption in the simulation was not real because of inherent porosity in the EPD coated layer; (b) a gap of 0.2 mm between the micro-reformer casing and the reaction plate would appear if temperature exceeded 650°C and this gap caused flow by pass-through channels. At the third and final part, copper substrate was coated and compared with S310 substrate. Results did not show so much better methane conversion because dimension were very small, which means temperature along the depth or length did not vary considerably. Stability analysis, reducing the channel sizes, redesigning the micro-reformer to add endothermic reaction (such as methane catalytic combustion) section will be our next studies.