Oxygen perovskite-type oxides

It is well known that dense ceramic membranes made of the mixture of ionic and electron conductors are permeable to oxygen at elevated temperatures. For example, perovskite-type oxides (e.g., La-Sr-Fe-Co, Sr-Fe-Co, and Ba-Sr-Co-Fe-based mixed oxide systems) are good oxygen-permeable ceramics. Figure 2.11 depicts a conceptual design of an oxygen membrane reactor equipped with an OPM. A detail of the ceramic membrane wall... 

The Incentive to modify our existing continuous-flow microunit to incorporate the square pulse capability was provided by our work on perovskite-type oxides as oxidation-reduction catalysts. In earlier work, it had been inferred that oxygen vacancies in the perovskite structure played an important role in catalytic activity (3). Pursuing this idea with perovskites of the type Lai-xSrxFeg 51 10 503, our experiments were hampered by hysteresis effects which we assumed to be due to the response of the catalyst s oxygen stoichiometry to the reaction conditions. 

Fereshteh, R., Caroline, S., James, A. F., 2002. Sphalerite activation and surface Pb ion concentration. Inter. J. Miner. Process, 67 43 - 58 Fierro, R. E., Tryk, D., Scherson, D., Yeager, E., 1988. Perovskite-type oxides oxygen electrocatalysis and bulk structure. Journal of Power Sources, 22 (3 - 4) 387 - 398... 

Figure 5. Time-averaged structure of a protonic defect in perovskite-type oxides (cubic case), showing the eight orientations of the centrai hydroxide ion stabiiized by a hydrogen-bond interaction with the eight next-nearest oxygen neighbors. ...

Oxygen Sensor Using Perovskite-Type Oxides... 

Y. Teraoka, H. Zhang, S. Furukawa and N. Yamazoe, Oxygen Permeation Through Perovskite-type Oxides, Chem. Lett. 1743 (1985). 

Figure 47. As oxygen ions move towards each other on account of lattice vibrations, die activation energy for proton jump is lowered, and die proton changes partner. According to Ref..192. (Reprinted from K. D. Kreuer, W. Munch, U. Traub and J. Maier, On Proton Transport in Perovskite-Type Oxides and Plastic Hydroxides , Ber. Bunsenges. Phys Chem. 102, 552-559. Copyright 1998 with...

An increasing amount of attention is being given to oxides as possible anodes for oxygen evolution because of the importance of this reaction in water electrolysis. In this connection, numerous studies have been carried out on noble metal oxides, spinel and perovskite type oxides, and other oxides such as lead and manganese dioxide. Kinetic parameters for the oxygen evolution reaction at a variety of single oxides and mixed oxides are shown in Table 3. 

In some oxides, formation of superstructures is merely due to oxygen ordering. A good example was demonstrated by Reller and coworkers in 1984, by showing many distinct superstructures in perovskite-type oxides CaMn03, t with oxygen contents of 2.5, 2.556, 2.667, 2.75 and 2.80 [38]. 

Some dense inorganic membranes made of metals and metal oxides are oxygen specific. Notable ones include silver, zirconia stabilized by yttria or calcia, lead oxide, perovskite-type oxides and some mixed oxides such as yttria stabilized titania-zirconia. Their usage as a membrane reactor is profiled in Table 8.4 for a number of reactions decomposition of carbon dioxide to form carbon monoxide and oxygen, oxidation of ammonia to nitrogen and nitrous oxide, oxidation of methane to syngas and oxidative coupling of methane to form C2 hydrocarbons, and oxidation of other hydrocarbons such as ethylene, methanol, ethanol, propylene and butene. 

Y. Teraoka, T. Nobunaga and N. Yamazoe, Effect of cation substitute on the oxygen semipermeability of perovskite type oxides. Chem. Lett., (1988) 503-506. 

The limits of integration are the oxygen partial pressures maintained at the gas phase boundaries. Equation (10.10) has general validity for mixed conductors. To carry the derivation further, one needs to consider the defect chemistry of a specific material system. When electronic conductivity prevails, Eqs. (10.9) and (10.10) can be recast through the use of the Nemst-Einstein equation in a form that includes the oxygen self-diffusion coefficient Dg, which is accessible from ionic conductivity measurements. This is further exemplified for perovskite-type oxides in Section 10.6.4, assuming a vacancy diffusion mechcinism to hold in these materials. 

The reductive (and oxidative) nonstoichiometry and the stability in reducing oxygen atmospheres of perovskite-type oxides was reviewed by Tejuca et al. [174]. Data from temperature programmed reduction (TPR) measurements indicate that... 

The considerations in this chapter were mainly prompted by the potential application of mixed-conducting perovskite-type oxides to be used as dense ceramic membranes for oxygen delivery applications, and lead to the following general criteria for the selection of materials... 

H. Kruidhof, H.J.M. Bouwmeester, R.H.E. van Doom and A.J. Burggraaf, Influence of order-disorder transitions on oxygen permeability through selected nonstoichiometric perovskite-type oxides. Solid State Ionics, 63-65 (1993) 816-822. 

H.-M. Zhang, Y. Shimizu, Y. Teraoka, M. Miura and N. Yamazoe, Oxygen sorption and catalytic properties of Lai-xSrxCoi-yFcyOs-s perovskite-type oxides. /. Catal., 121 (1990) 1367-1370. 

K. Fueki, J. Mizusaki, S. Yamauchi, T. Ishigaki and Y. Mima, Nonstoichiometry and oxygen vacancy diffusion in the perovskite type oxides Lai-xSrxCoOs-s, in P. Barret and L.C. Dufour (Eds.), Proceedings of the 10th International Symposium on Reactivity of Solids 1984. Elsevier, Amsterdam, 1985, pp. 339-343. 

J.A.M. Van Roosmalen and E.P.H. Cordfunke, A new defect model to describe the oxygen deficiency in perovskite-type oxides. /. Solid State Chem., 93 (1991) 212-219. 

FIGURE 9.3 Diagram for the variation of the oxygen/metal stoichiometry with the partial pressure of oxygen for different perovskite-type oxides. (From figure 1 of Girdauskaite et al., 2007. J. Solid State Electrochem. 11, 469-477, with permission.)... 

---