Rational selection of MIEC materials in energy production processes

Quantifying Electronic and Ionic Conductivity Contributions in Carbon/Polyelectrolyte Composite Thin Films

“…[3][4][5] MIEC materials are critically important in many electrochemical technologies, for example in battery electrodes, [6][7][8][9][10][11][12][13] fuel-cell electrodes, [14][15][16] and in certain types of membrane reactor. [17][18][19][20] A simple measurement of electrical resistance/conductance on a bulk sample, for example from the current obtained upon application of a potential difference between two points on the sample using current-carrying electrodes, can provide values for resistivity/conductivity but it does not provide information on the nature of the charge carrier(s). Four-point-probe (e.g.…”

Fabrication and characterization of dense BaCo0.7Fe0.2Nb0.1O3−δ tubular membrane by slip casting techniques

“…Mixed ionic-electronic conducting (MIEC) dense ceramic membranes have attracted considerable attraction because of their application in oxygen separation, catalytic membrane reaction and oxyfuel combustion processes [1][2][3][4][5][6]. MIEC membrane reactor has been successfully applied to produce syngas by partial oxidation reforming of CH 4 in COG (coke oven gas) by our group [7].…”

Carbon Dioxide Reforming of Methane using an Isothermal Redox Membrane Reactor

“…[26] Perovskitesc ircumvent changes of the crystalc lass and phase of stoichiometric metal oxide redox materials [2,[8][9][10] and have attracted much attention for fuel cells ando xygen separation due to their tunable oxygen vacancy concentrations and high oxygen vacancy conductivities. [25,31] We employ electronic structure theory to quantify the thermodynamic limitations of LSCF redox membranes and to identify advanced perovskite compositionsf or solar-drivenD RM. Thet hermochemical stability and the reactione nergetics for perovskites are calculated from the scaling relation [10,39] [39] shown with Figure 4D.P lotting the data for perovskites togetherw ith those for binary metal oxides shows,i nF igure 4A,t hat perovskites can reproduce the redox energetics of expensive or toxic materials [15] -such as LaCuO 3 ,a nd CO from CH 4 at about the same rate as CO from CO 2 .C H 4 conversion reaches 17 %, whereas the CO 2 conversion is at maximum 8.0% due to CH 4 decomposition.…”

“…[29,30] Results and Discussion This is based on its superioro xygen conductivitya nd typically high oxygen vacancy concentrations, stability of the nonstoichiometric cubic phase,t he redox activityo fc obalta nd iron, and the relatively low carbonate formation tendency. [2,6,25,31,32] To optimize performance,t he following section providesaguide for the rational design of prospective redox materials using optimized reactiont hermodynamics.O neend open tubular LSCF redox membranes were fabricated using ap hase inversion technique and evaluated for DRM using at ube-in-shell membrane reactor, as described in detail in the Supporting Information.F igure 1A shows the isothermal productionr ates of CO by CO 2 splitting in the membrane cavity at steady-state.F igure 1B shows the equivalent rates for the productiono fC Oa nd H 2 from CH 4 reforming in the reactors hell. Thef ormationo fC Of rom CH 4 is relatively stable over the course of 20 min and, as expected from mass balance, approximately equal to CO formation from CO 2 .P urging the reactor in absence of the redox membrane at these temperatures with CO 2 did not yield CO.T his confirms that CO 2 is reduced into CO at the inner membrane surface and that the abstracted oxygen is transported across the membrane to activate CH 4 at the outer membrane surface,yielding CO and H 2 .…”

“…ABO 3Àd þðdÀeÞCO ðgÞ þ 2 ðdÀeÞH 2ðgÞ ð2Þ Thec ontinuous production of carbon monoxide( CO) and hydrogen (H 2 )b yd ry reforming of methane (CH 4 )i sd emonstrated isothermally using ac eramic redox membrane in absence of additional catalysts.T he reactort echnology realizes the continuous splitting of CO 2 to CO on the inner side of at ubularm embranea nd the partialo xidation of CH 4 As the oxygen is continuously replenished from CO 2 ,t he formationo fathick layer of reduced metal oxide is avoided, which,i nt urn, augments the oxygen conduction kinetics. [24,25] Overall,C O 2 and CH 4 are reformed into solar syngas,w hose energetic value has been solar-upgradedb yafactor of 1.31 over that of the methane feedstock. [26] To achieve this,t he redox membrane provides variable metal oxidation states accessible through oxidationw ith CO 2 and reduction with CH 4 at elevated temperatures.T his is in contrast to the previously reported thermolysis of H 2 Oa nd CO 2 yielding O 2 ,H 2 ,a nd CO,d riven by O 2 separation using dense ceramic membranes, [27,28] and an extension of the previously reported membrane-assistedproduction of H 2 from H 2 Ousing areducing gas such as CH 4 ,CO, or H 2 .…”