Membrane reactor proton-conducting membranes

J. Li, H. Yoon, T. Oh, E. D. Wachsman, High temperature SiCeo,9Euo.i03 6 proton conducting membrane reactor for H2 production using the water-gas shift reaction, Appl. Catal. B Environ. 

Karagiannakis G, Kokkofitis C, Zisekas S and Stoukides M (2005), Catalytic and electrocatalytic production of H2 from propane decomposition over Pt and Pd in a proton-conducting membrane-reactor , Catal Today, 104,219-224. 

Karagiannakis G, Zisekas S, Kokkofitis C and Stoukides M (2006), Effect of H2O presence on the propane decomposition reaction over Pd in a proton conducting membrane reactor , AppZ Catal A-Gen, Mil, 265-271. 

Li, J., Yoon, H., Wachsman, E. D. (2012). Carbon dioxide reforming of methane in a SrCeo.7Zro.2Euo.1O3a proton conducting membrane reactor. International Journal of Hydrogen Energy, 37(24), 19125-19132. 

The double-chamber reactor is a typical cell reactor in which the anode and the cathode are exposed to different gas mixtures. A schematic diagram of a double-chamber reactor with a proton-conducting membrane is presented in Figure 18.3. 

Finally, the proton-conducting membranes based on perovskites can be used for steam permeation. Such a concept has been demonstrated for fuel cells operating at zero current, but could also be extended to membrane reactor applications [65]. In this concept, water permeates from the feed to the permeate side of the membrane, promoting steam reforming of methane. The generated H2 splits at the permeate/membrane surface, permeating back to the feed side as a Fara-daic flux and reacting with O2. 

Proton-conducting membranes can be applied to reduce NO emission by combining heterogeneous catalysis and solid-state electrochemistry. The solid electrolytes in membrane reactors serve to control chemisorp-tive bonds electrochemically and enhance catalytic activity. Figure 6.8 shows a schematic diagram of a steam electrolysis cell constructed with a proton conductor for reducing NO. Steam is electrolyzed at the anode. The electrode reactions are... 

Table 6.6 Ammonia synthesis in proton-conducting membrane reactors... 

Fu, X.-Z., Luo, J.-L., Sanger, A.R., Xu, Z.-R. and Chuang, K.T. (2010) Fabrication of bi-layered proton conducting membrane for hydrocarbon solid oxide fuel cell reactors. Electrochimica Acta, 55,1145-1149. 

An interesting application of proton-electron conducting membranes has recently been reported by Li et al. [2.76]. These authors studied the conversion of CH4 first to C2H4 and its subsequent direct catalytic aromatization to benzene and other valuable aromatic hydrocarbons. Their reactor configuration is shown schematically in Figure 2.3. The two distinct additional features of their work are the use of an active catalyst for the reaction itself, (Mo/H-ZSM5), and the use of asymmetric membranes with a thin (10-30 pm)... 

A newly-designed photoelectrocatalytic (PEC) reactor for CO2 reduction, which combines photocatalysis by Ti02 and electrocatalysis by carbon nanotubes (CNT), has recently been proposed (Fig. 7) [152]. A proton-conductive Nafion membrane connects the Ti02 and CNT. Irradiation of the combined system of nano-structured Ti02 deposited on a metal Ti electrode with Pt modified CNT deposited on carbon sheet caused water splitting to H2 and O2. A half-cell for the cathodic electrode, i.e., Pt or Fe modified CNT electrode, produces various organic molecules such as 2-propanol due to electrocatalytic reduction of CO2 on the electrode. The proposed PEC reactor is incomplete in its present state. However, these systems are expected to couple water splitting and CO2 reduction, and thus it may establish a new artificial photosynthetic system. 

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