Pressure-dependent catalytic combustion of low-concentration methane: mechanisms and kinetic behavior on Mn-Ce-Cu catalysts

This work addresses the pressure-induced reaction kinetics and investigates the fundamental relationship between pressure and catalytic combustion activity, focusing on the kinetics, transformation of active species and reaction sites. These findings provide critical insights into pressure-dependent catalytic behavior and offer valuable knowledge for advancing industrial applications. • CH 4 reaction order is increased to strengthen the adsorption at active site under pressure. • Pressure causes electron transfer of metal components to reactive oxygen species. • Pressure promotes the rapid conversion of *O latt and consumption of *CH 4 and *O latt . The large-scale application of low-concentration CH 4 catalytic combustion in mine exhaust gas turbines requires operating under high pressure. However, most existing research is conducted at normal pressure, with limited understanding of the pressure-induced reaction kinetics and the migration mechanisms of reactive species, which hampers industrial development. This work addresses the pressure-induced reaction kinetics and investigates the fundamental relationship between pressure and catalytic combustion activity, focusing on the kinetics, transformation of active species, and reaction sites. The results show that elevated pressure improves catalytic reaction kinetics and the migration of active species. At 0.7 MPa, CH 4 conversion increases by approximately 20 %, and the T 90 temperature is reduced by about 30 °C. After 24 h of reaction, the catalyst becomes more porous, and CH 4 conversion only decreases by 2.5 %. High reaction pressure increases the CH 4 reaction order, enhances the adsorption and coverage of *CH 4 at the active sites, and induces electron migration from metal active components to oxygen species, which boosts the reactivity of active oxygen. This process accelerates the conversion of surface oxygen (*O sur ) to lattice oxygen (*O latt ). The enhanced *CH 4 adsorption capacity and the reactivity of *O latt under high pressure lead to the rapid consumption of *O latt . These findings provide critical insights into pressure-dependent catalytic behavior and offer valuable knowledge for advancing industrial applications.