Catalytic combustion of CH4 and H2 into micro-monoliths

Catalytic combustion of CH4 or other gaseous HCs in microscale channels is becoming the key technology for various portable power generation devices that could replace current batteries to meet the increasing demand for more efficient, longer lasting and more environmentally friendly energy-consuming utilizations. New type of catalysts for the CH4/H2/air lean mixtures oxidation in drastic conditions were proposed and investigated; they were lined on SiC monoliths (dimensions 6 mm × 6 mm × 22 mm) and tested into a lab-microreactor able to reach high power density (7.6 MWth m−3). The catalysts were directly deposited on the monoliths via in situ solution combustion synthesis. The most interesting performance on the oxidation of CH4/H2/air lean mixtures was obtained with the monolith 2% Pt/(5% Al2O3), 2% Pd/(5% NiCrO4), followed by 2% Pd/(5% CeO2·ZrO2) and 2% Pd/(5% LaMnO3·ZrO2); the monolith 2% Pt/(5% Al2O3) behave better by burning CH4 or H2 alone. For the Pd-based catalysts, the addition of H2 to the reactive mixture led to an improvement of the CH4 combustion, whereas this did not happen for the Pt-based one. The addition of H2 to the gas mixture allowed to a decrease of the CH4-T50 and CH4-T100 compared to the combustion of CH4 alone, and the conversion curves slope becomes steeper: the higher the H2 concentration, the higher the mixture reactivity towards CH4 oxidation, probably due to the larger production of H2 reactive radicals (OHradical dot).