Methane steam reforming at low temperatures in a BaZr0.7Ce0.2Y0.1O2.9 proton conducting membrane reactor

Abstract

The feasibility of Methane steam reforming (MSR) at low temperatures (450–650°C) was studied in a Ni-BZCY72/BZCY72/Cu proton conducting membrane reactor, which allowed for the simultaneous separation of hydrogen. The cell reactor was first tested under open-circuit conditions, i.e., with the reactor operating as a catalytic reformer. The impact of several parameters, such as steam to carbon feed ratio, the operating temperature and the total flow rate was evaluated. The Ni-BZCY72 electrode exhibited high catalytic activity with methane conversion close to thermodynamic equilibrium, which was attributed to the high nickel content (45wt.% after full reduction), as well as to the presence of ceria and zirconia in the support. Carbon dioxide was the main carbonaceous product with a molar ratio to carbon monoxide higher than 9, indicating that the Water Gas Shift reaction was predominant in the process. When hydrogen was electrochemically transported from the Ni-BZCY72 anode to the Cu cathode, a significant increase in methane conversion and hydrogen yield was observed. The methane conversion and hydrogen yield were improved by up to 50% in the temperature range of 550–650°C over their corresponding open-circuit values. The BZCY72 perovskite exhibited satisfying proton fluxes and transference numbers at all temperatures and applied cell voltages examined. Finally, the Ni-BZCY72 reactor cell showed excellent chemical stability and durability, as well as coke tolerance for 24h on stream.