Promising Directions in Chemical Processing of Methane from Coal Industry. Part 3. Catalytic Tests

Abstract

For the processing of coal mine methane into hydrogen-containing gas, a catalytic process of methane tri-reforming (СH₄ + O₂ + CO₂ + H₂O) was proposed and its component reactions were studied – partial oxidation (СH₄ + O₂, POM), dry reforming (СH₄ + CO₂, DRM) and steam reforming (СH₄ + H₂O, SRM) of methane. Promoted nickel supported on aluminum oxide was used as a catalyst. Experiments were carried out by varying temperature (600–850 ºC), contact time (0.04–0.15 s), linear feed rate (40–240 cm/min) and composition of the reaction mixture (POM – СH₄ : O₂ : He = 1 : (0.5–0.7) : (3.3–3.4); DRM – СH₄ : CO₂ : He = 1 : (0.8–1.4) : (2.6–3.2); SRM – CH₄ : H₂O : He = 1 : (0.8–2.0) : (2.0–3.2)). Optimal reaction conditions were determined to ensure maximum efficiency of hydrogen production by reforming methane-containing mixtures of various compositions (temperature in the range of 800–850 ºC, contact time 0.15 s, linear feed rate 160 cm/min, molar ratio of CH₄ : O₂ = 1 : 0.5 for POM, CH₄ : CO₂ = 1 : 1 for DRM and CH₄ : H₂O = 1 : 1.1 for SRM). The degree of catalyst carbonization during the reactions was reduced (from 3 to 1.5% for POM, from 20.7 to 2.2% for DRM, and from 15.2 to 0.4% for SRM) due to an increase in the O/C molar ratio in the initial reaction mixture. Regulation of H₂/CO molar ratio was achieved over a wide range (0.9–6.5). It has been shown that the hydrogen concentration in the resulting hydrogen-containing mixture is determined by the type of process and is equal to 30±5 vol.%.