A system including enriching coal bed methane by solar energy and selective catalytic reduction

Highlights: • A system that combines enriching CBM with solar energy and SCR of NO_x is proposed. • The enriched CH₄ is utilized as the reductant in SCR with catalyst La_0.8Sr_0.2MnO₃. • The concentration of CH₄ can be enriched to 80% through 200 enriching pipe units. • In the CH₄-SCR system, the maximum conversion ratio of NO can reach to 80%. - Abstract: Enriching CBM (coal bed methane) and then making good use of the enriched CH₄ have great significance in protecting the environment. This paper proposes a new system that uses solar energy to enrich CBM and then utilizes the enriched CH₄ as the reductant in SCR (selective catalytic reduction) of NO_x with a new catalyst (La_0.8Sr_0.2MnO₃). Theory research, numerical simulation, experiments were done to investigate the key factors of the enrichment such as the initial CH₄ concentration, the temperature field. Results indicate that when the temperature difference $\Delta T=450-300=150K$, 200 enriching pipe units as in this experiment model can make the final mole fraction of CH₄ reach to 80%. Besides, a new SCR of NO_x by CH₄ with catalyst La_0.8Sr_0.2MnO₃ is presented in this paper and the enriched CH₄ is the reducing agent. Experiments were done to investigate the efficiency of the new catalyst. In the new CH₄-SCR system, the maximum conversion ratio of NO can reach to 80% and the mass concentration of NO at the outlet can be lower than 20 mg/m³ in a proper condition. This new system can make good use of the solar energy to enrich CBM and present an efficient way to use the enriched CBM, which is friendly to the environment.