Methane production by a combined Sabatier reaction/water electrolysis process

Abstract

This paper describes production of synthesis gas (syngas) and its optimization through a one-step innovative 1 kW prototype of alkaline water electrolysis (patented), using graphite electrodes and without gas separation (containing CO, CO2, H2 and small amounts of O2). The behavior of the syngas composition and flow rate has been studied and optimized, changing operational parameters such as temperature, pressure and current intensity, and testing two different kinds of electrodes. Afterwards, the best syngas composition has been sent into a catalytic reactor (filled with a bed of Ni/CaO-Al2O3 catalyst) in order to achieve methane production, at 1 bar and different temperatures.The main competitive advantage of this process lies in the built-in of an innovative technology product, from renewable energy (RE) power in remote locations, such as islands, villages in mountains as an alternative for energy storage for mobility constraints. In the catalytic reactor it was possible to achieve a CH4 yield of 25.5 %, a CO2 conversion into CH4 of 44.2% and a CH4 selectivity of 96.5%.