Fuel-rich methane oxidation in a high-pressure flow reactor studied by optical-fiber laser-induced fluorescence,multi-species sampling profile measurements and detailed kinetic simulations

A versatile flow-reactor design is presented that permits multi-species profile measurements under industrially relevant temperatures and pressures. The reactor combines a capillary sampling technique with a novel fiber-optic Laser-Induced Fluorescence (LIF) method. The gas sampling provides quantitative analysis of stable species by means of gas chromatography (i.e. _CH4${\mathrm{CH}}_4$, _O2,CO,_CO2${\mathrm{O}}_2\text{,}\mathrm{CO}\text{,}{\mathrm{CO}}_2$, _H2O,_H2${\mathrm{H}}_2\mathrm{O}\text{,}{\mathrm{H}}_2$, _C2${\mathrm{C}}_2$_H6${\mathrm{H}}_6$, _C2${\mathrm{C}}_2$_H4${\mathrm{H}}_4$), and the fiber-optic probe enables in situ detection of transient LIF-active species, demonstrated here for C_H2${\mathrm{H}}_2$O. A thorough analysis of the LIF correction terms for the temperature-dependent Boltzmann fraction and collisional quenching are presented. The laminar flow reactor is modeled by solving the two-dimensional Navier–Stokes equations in conjunction with a detailed kinetic mechanism. Experimental and simulated profiles are compared. The experimental profiles provide much needed data for the continued validation of the kinetic mechanism with respect to _C1${\mathrm{C}}_1$ and _C2${\mathrm{C}}_2$ chemistry; additionally, the results provide mechanistic insight into the reaction network of fuel-rich gas-phase methane oxidation, thus allowing optimization of the industrial process.