Effect of catalyst formulation (Rh, Rh–Pt) on the performance of a natural gas hybrid catalytic burner

An extensive experimental campaign was carried out on a prototype hybrid radiant burner with ultra low emissions based on the novel concept of fuel-rich catalytic + homogeneous flame combustion with interstage heat transfer. Special attention was paid to the impact of two alternative active formulations for the catalytic partial oxidation stage (0.5% Rh and 0.25–0.25% Rh–Pt on γ-Al2O3) on the general performance of the burner, and particularly on its NOx emissions. The hybrid burner was operated with methane in the 4–30 kW power range, at varying the feed equivalence ratio ϕ from 2.0 to 3.6. InfraRed thermography was used to simultaneously investigate the catalytic surfaces and the corresponding subsequent diffusion flames. Moreover this work attempts to correlate detailed experimental data on syn-gas compositions at the exit of the CPO reactor with emissions in the exhaust. Experimental evidence of the reduction of both thermal and prompt NOx formation mechanism is presented.