Mixed protonic-electronic membrane

The use of a mixed oxygen ion-electronic conductor membrane for oxygen separation with direct reforming of methane, followed by the use of a mixed protonic-electronic membrane conductor for hydrogen extraction has also been proposed in the literature [34]. The products are thus pure hydrogen and synthesis gas with reduced hydrogen content, the latter suitable, for example, in the Fish-er-Tropsch synthesis of methanol [34]. 

Figure 2.1 Hydrogen transport through a dense mixed protonic-electronic membrane.

Mixed Protonic-Electronic Conducting Membrane for Hydrogen Production from Solid Fuels... 

Mixed Protonic-Electronic Conducting (MPEC) Membrane... 

Qi X, Lin YS. Electrical conduction and hydrogen permeation through mixed proton-electron conducting strontium cerate membranes. Solid State Ionics. 2000 130 149. 

Figure 1.1a shows schematically the operation of a membrane that is permeable to hydrogen molecules (corresponding to a porous membrane or a dense material in which molecules dissolve and diffuse) or to neutral hydrogen atoms (corresponding to a material in which hydrogen dissolves dissociatively, as in a metal). Figure 1.1b shows schematically how a mixed proton-electron conductor performs the same process by so-caUed ambipolar diffusion of both protons and electrons in the same direction to maintain electroneutrality and zero net current. 

The WGSR in a mixed protonic-electronic conducting SrCeo.9Euo.i03. membrane coated on a Ni-SrCeOa. support was studied by Li et al. [66], At 900°C a 46% increase in CO conversion was achieved, with the feed stream having a H2O/CO ratio of 2. 

---