Catalytic combustion of CH4-H2-CO mixtures at pressure up to 10 bar

Catalytic combustion has attracted a renewed interest as an alternative route to homogeneous combustion of low BTU mixtures (H2, CO). As a matter of fact, the partial or total replacement of natural gas (i.e. CH4) with low BTU fuels is usually accompanied by a reduction of fuel dilution and an increase of NOx emissions. In this work we experimentally investigate the effect of the partial substitution of CH4 with H2/CO mixtures (representatives of syngas) over a 20wt%LaMnO3/La-γAl2O3 based monolith. The tests were carried out under self-sustained and high pressure conditions (up to 10 bar). The mixtures studied are characterized by the same overall heating value. Three H2/CO ratios were investigated. Results showed that methane substitution with syngas is useful to obtain full fuel ignition under less severe conditions (i.e. at lower pressure keeping constant the pre-heating temperature) and that ignition is mainly driven by CO combustion, which is the most reactive fuel among CH4, H2 and CO itself on LaMnO3 catalyst.

► We studied the partial substitution of CH4 with syngas in the catalytic combustion.
► LaMnO3 structured catalyst has been used and tested under autothermal conditions.
► Syngas containing mixtures ignite at less severe conditions (lower pressure).
► Ignition is mainly driven by CO combustion, the most reactive fuel on LaMnO3.
► Syngas and methane reaction fronts appear separated.