Two fluidized bed membrane reactor concepts for hydrogen production via autothermal reforming of methane with integrated CO2 capture are proposed. Ultrapure hydrogen is obtained via hydrogen perm-selective Pd-based membranes, while the required reaction energy is supplied by oxidizing part of the CH4 in situ in the methane combustion configuration or by combusting part of the permeated H2 in the hydrogen combustion configuration (oxidative sweeping). In this first part, the technical feasibility of the two concepts has been studied experimentally, investigating the reactor performance (CH4 conversion, CO selectivity, H2 production and H2 yield) at different operating conditions. A more detailed comparison of the performance of the two propo...