Experimental Study on Catalytic Combustion of Methane in a Microcombustor with Metal Foam Monolithic Catalyst

Abstract

Utilizing catalysts in microcombustors is probably an excellent practical solution to stabilize fuel combustion because of the relatively fast reaction speed. In the present work, the monolithic catalyst Pd/A2O3/Fe-Ni with metal foam as matrix was used inside a 5 mm in diameter microcombustor. Then the effects of inlet velocity and equivalent ratio on catalytic combustion characteristics of methane were studied experimentally. The results showed that the methane and air mixture with the stoichiometric ratio Φ = 1.0 could be ignited at v = 0.2–0.6 m/s. The velocity of premixed mixture had a great influence on the catalytic combustion of methane. The larger the inlet velocity, the higher the temperature and the brighter the flame were. The experiment results also showed that the equivalence ratio had a large essential impact on the catalytic combustion, especially for the lean mixture of methane and air. It seemed the addition of the porous matrix with catalysts could significantly extend the limits of stable combustion. In the detection of exhaust gas, CO selectivity increased and CO2 selectivity decreased with the equivalence ratio. When Φ was between 0.94 and 1.0 m/s, a little amount of hydrogen was produced due to the lack of oxygen. The measured conversion of methane to CO and CO2 was very high, usually greater than 99%, which indicated the excellent performance of the catalyst.

CH4/air combustion in a microscale recirculating heat exchanger: Sizing design using the heat transfer approach

“…13 Catalysts with higher surface-to-volume ratio promote more sites for the adsorption of fuel and oxidizer. 14 Hence, catalytic combustion can improve flame stability and conversion efficiency in microcombustors. Li et al conducted a numerical analysis to study the geometry and flame temperature on a methane air-premixed microcombustion.…”

“…Slotted or controllable slotted bluff body catalytic microcombustors have been shown to exhibit better combustion performance with stable flame when the gap width is maintained at 0.6 mm 13 . Catalysts with higher surface‐to‐volume ratio promote more sites for the adsorption of fuel and oxidizer 14 . Hence, catalytic combustion can improve flame stability and conversion efficiency in microcombustors.…”

Two-Dimensional Numerical Study of Methane-Air Combustion Within Catalytic and Non-catalytic Porous Medium

“…Qu and Feng ( 2015 ), Feng and Qu ( 2016 ) studied the catalytic combustion of premixed methane/air in a two-zone perovskite-based alumina (Al 2 O 3 ) pileup-pellets burner, and indicated that the flame stability limits increased with the increase of equivalence ratio or pellet diameter. Li et al ( 2018 ) used a metal foam catalyst to catalyze methane (CH 4 ) combustion in a micro-combustion chamber and investigated the effects of inlet velocity and equivalence ratio on catalytic combustion characteristics of methane. These results show that a mixture of methane/air has an equivalent ratio of 1.0 and that a mixed fuel with an inlet velocity of 0.2–0.6 m/s can achieve combustion.…”

Comparative Study of the Characteristics and Activities of Pd/γ-Al2O3 Catalysts Prepared by Vortex and Incipient Wetness Methods

“…Several Pd catalysts have also been developed using other supports. Liu et al [10] developed a rice husk derived porous silica support for a Pd-CeO 2 catalyst for low temperature combustion of methane with 90% conversion at 325 • C. A monolithic Pd/Al 2 O 3 /Fe-Ni catalyst with metal foam as matrix in a microcombustor improved methane conversion to more than 99% [11]. Cargnello et al [12] developed a novel Pd@CeO 2 /hydrophobic-Al 2 O 3 core-shell catalyst that had methane conversions of 50% and 100% at 325 • C and 400 • C respectively.…”