Abstract
In this study, surface of the Cu/Mn/ZnO catalyst in water-based slurry can be modified simply by PVA which was used as dispersant and organic binder. The well-dispersed catalyst slurry forms a crack-free coating and can be directly injected into open microchannel without mask or sacrificial layer on the top surface of silicon microcahnnel before anodic bonding with Pyrex glass. To further improve the adherence of catalyst, porous silicon was fabricated in microchannel. Porous silicon with pore size less than 1 μm can be etched by 20% HF, 10 mA/cm2 current density for 600s followed by 1 M NaOH etching on a P-type silicon wafer. Catalyst coating (cat. 10 wt.%, PVA 2 wt.%) shows good adhesion on porous silicon with only 6 wt.% loss in the ultrasonic vibration test (180 W, 20 min). In microchannel activity test, three different geometries of microchannel (blank, straight, cratered) were used to test the efficiency of catalyst in the partial oxidation of methanol (POM) reaction. With the same amount of catalyst loading, microchannel with cratered design has superior performance over other two designs due to the local thicker catalyst layer. Since catalyst layer has low thermal diffusivity, 0.98 mm2/s measured in this research, thicker catalyst layer can decrease the loss of heat generated from the POM reaction to the surroundings and enhance the catalytic performance. So far, microchannel with cratered design can be deposited with catalyst up to 24.4 mg and has a hydrogen production rate of 0.85 mmolh-1 and 86% methanol conversion at 200 oC under the feed rate of 2SCCM.