Mixed Protonic-Electronic Membrane Reactors; Converting Hydrocarbon Resources and CO2 to Fuels


Prof. Eric D. Wachs­man
Direc­tor, Mary­land Ener­gy Inno­va­tion Insti­tute
William L. Crentz Cen­ten­ni­al Chair in Ener­gy Research
Uni­ver­si­ty of Mary­land, Col­lege Park, MD

Abstract:  Mem­brane reac­tor tech­nol­o­gy holds the promise to cir­cum­vent ther­mo­dy­nam­ic equi­lib­ri­um lim­i­ta­tions by in-situ removal of prod­uct species, result­ing in improved chem­i­cal yields.  Recent advances in mixed-con­duct­ing oxide-mem­brane tech­nol­o­gy present the pos­si­bil­i­ty for a dra­mat­ic reduc­tion in the cost of con­vert­ing petro­le­um, coal and bio­mass derived feed stocks to hydro­gen and oth­er “val­ue added” hydro­car­bons.  We have devel­oped nov­el mem­brane reac­tor tech­nol­o­gy, based on high tem­per­a­ture pro­ton con­duc­tors, that can con­vert a wide range of hydro­car­bons to pure H2, and syn­gas for syn­the­sis of liq­uid fuels and chem­i­cal feed stocks. By simul­ta­ne­ous H2 per­me­ation and catal­y­sis, we have demon­strat­ed the abil­i­ty to increase water gas shift yields >70% over ther­mo­dy­nam­ic lim­i­ta­tions. Sim­i­lar­ly, we have demon­strat­ed increas­es in steam reform­ing yields, and the abil­i­ty to reform CH4 with CO2.

More recent­ly we have devel­oped sin­gle-step gas to liq­uid reac­tors that con­vert nat­ur­al gas to C2+ prod­ucts with high yields and no unwant­ed oxi­da­tion byprod­ucts. The direct uti­liza­tion of CH4 and CO2 to simul­ta­ne­ous­ly pro­duce C2+ hydro­car­bons (C2 and aro­mat­ics) and syn­gas (CO and H2) on oppo­site sides of a mixed pro­ton­ic-elec­tron­ic con­duct­ing SrCe0.7Zr0.2Eu0.1O3-δ mem­brane reac­tor is demon­strat­ed. On one side (inte­ri­or) of the mem­brane reac­tor, direct non-oxida­tive methane con­ver­sion (DNMC) over an iron/silica cat­a­lyst pro­duces C2+ hydro­car­bons and H2. On the oth­er side (out­er sur­face) of the mem­brane, per­me­at­ed H2 (dri­ving the DNMC reac­tion) reacts with a CO2 sweep gas to form CO and water via the reverse water gas shift (RWGS) reac­tion. This nov­el sin­gle H2-per­me­able mem­brane reac­tor simul­ta­ne­ous­ly address­es both reduc­tion of green­house gas (CO2 and CH4) emis­sions as well as pro­duc­tion of val­ue-added hydro­car­bon prod­ucts (C2+, CO, and H2) with in situ gas sep­a­ra­tion.