Performances of tubular La0.8Sr0.2Fe0.7Ga0.3O3−δ mixed conducting membrane reactor for under pressure methane conversion to syngas

The performances of the Mixed oxygen Ion and Electronic Conducting (MIEC) membrane reactor with surface catalyst was investigated for the methane conversion to synthesis gas, at operating conditions as close as possible to industrial requirements (pressurized syngas, high temperature, CH4 + H2O mixture as feed). A dense self supported tubular membrane in one closed end geometry, made from the perovskite composition La0.8Sr0.2Fe0.7Ga0.3O3−δ (LSFG), was elaborated by isostatic pressing and was coated with a La0.8Sr0.2Fe0.7Ni0.3O3−δ (LSFN) porous catalyst. Results show that LSFG membrane can be operated under pressure and pure methane as dry feed for more than 142 h without any fracture. Moreover, syngas production (X(CH4) and S(CO)) are greatly related to the reactor design and feed contact time. As a result, CH4 conversion, CO selectivity, and oxygen permeation flux through the membrane can reach respectively 74%, 50% and 0.9 N m3/m2 h at 1173 K, with CH4 + H2O mixture, S/C = 1 (Steam/Carbon ratio), PFeed = 0.3 MPa and a feed contact time of 13 s. Microstructure observations have shown Ni metallic exudation from LSFN surface catalyst and strontium rich continuous layer at catalyst/membrane interface under working conditions. However, these chemical/structural modifications did not seem to be detrimental to performances during short test duration (142 h).