Plasma catalytic steam methane reforming for distributed hydrogen production

Steam methane reforming (SMR) via thermal catalytic approach is one of the dominant sources of industrial hydrogen, however it proceeds with slow response and low specific productivity. Here we demonstrate a plasma catalytic SMR for distributed hydrogen production, for which warm plasma by gliding arc discharge initiates the reaction, followed by Ni-based catalyst in a heat-insulated reactor without extra heating. In terms of the plasma alone process, specific energy input (SEI), steam/CH4 ratio (S/C) and total inlet flow rate (F-t) contribute to the methane conversion. In parallel, SEI and S/C account for the decrease in C2Hx selectivity hence the increase in selectivity of CO and CO2, while with F t all the selectivity is approximately constant. The reaction pathway represented by the selectivity can be influenced by SEI and S/C rather F-t. To utilize the heat and active species with the reaction in plasma zone, Ni/CeO2/Al2O3 catalyst bed is coupled. For the coupled process, the conversion approaches the thermodynamic equilibrium values, with the favorable dismissed C2Hx selectivity thus the complete selectivity to CO and CO2. The coupled process was maintained steady for six hours, and the methane conversion of 90% at total hydrogen (t-H-2) production rate of 2.7 SLM is achieved under optimum conditions of SEI, S/C, F-t and gas hourly space velocity (GHSV) of 110 kJ/mol, 3, 3 SLM and 18,000 ml.g(-1) h(-1). Compared to 59% and 2.3 kW h/Nm s of the plasma alone process, such a coupled process achieves the energy efficiency (of methane to t-H-2) of 75% and the low energy cost of 1.5 kW h/Nm s . Consequently, our approach of plasma catalytic SMR features the merits of rapid response, compact system and high specific productivity, which can be anticipated for the emerging needs of distributed hydrogen generation.