Si based methanol catalytic micro combustor for integrated steam reformer applications

Catalytic methanol micro combustor was built by micromachining of (1 0 0) silicon and Borofloat 33 (Schott) glass. Pt/CeO2 catalyst precursor was prepared by wet impregnation of CeO2, synthesized by hard template method from the solution of dihydrogen hexachloroplatinate hydrate and deposited as a multiple thin film into the combustion chamber. The combustion process was characterized by considering thermodynamic properties such as light-off temperature and thermal response for various input flow rates and premixing conditions. Ignition regimes for methanol–O2 and methanol–air mixtures fed into the micro combustion chamber via methanol saturator were studied. By analyzing the amount of output water it was shown that the air carrier gas provided lower combusting efficiency compared to oxygen due to higher required flow rates of the former and consequently the reduced residence time. In addition to that, significant influence of outlet combustor orifice size on the thermal response and temperature was determined. After the initial preheating to provide light-off temperature between 100 and 200 °C an autonomous and stable combustor operation at temperatures over 300 °C was obtained with liquid methanol consumption rate of 1.45 ml h−1.

► Microcombustor response depends strongly on the light-off temperature.
► Final temperature primarily depends on the methanol partial pressure.
► Combustor outlet size affect significantly the temperature and rise time.
► Combustor with 7 mg Pt/CeO2 catalyst requires 1.45 ml h−1 methanol at 320 ± 2 °C.