Oxidized solid oxygen carrier

The oxidized solid oxygen carrier is subsequently circulated into reactor 2, where it is reduced by the fuel (which is consequently oxidized) either to metal or to a reduced oxide form. 

The pros and cons of oxidative dehydrogenation for alkene synthesis using doped cerianites as solid oxygen carriers are studied. The hydrogen oxidation properties of a set of ten doped cerianite catalysts (Ce0.9X0.1Oy, where X = Bi, In, La, Mo, Pb, Sn, V, W, Y, and Zr) are examined under cyclic redox conditions. X-ray diffraction, X-ray photoelectron spectroscopy, adsorption measurements, and temperature programmed reduction are used to try and clarify structure-activity relationships and the different dopant effects. 

The ozunides are characterized by the presence of the ozonide ion, OJ. They are generally produced by the reaction of the inorganic oxide and ozone. Sodium ozonide, NaO potassium ozonide, KO3 rubidium ozonide, RbC>3 and cesium ozonide, CsC>3. have all been reported. Ammonium ozonide, NH4O3, and tetramethylammonium ozonide, (CH a - NO3, have been prepared at low temperatures. Whereas the inorganic ozonides are of potential importance as solid-oxygen carriers in breathing apparatus, they are not produced commercially. 

In a first fundamental approach, the process is schematically shown in Figure 37.1. It is composed of two reactors in the first reactor, the solid oxygen carrier is being oxidized by the oxygen of the oxidant into its oxidized form according to the following reaction ... 

In the transport bed process the oxidation of -butane by (V0)2P20y and the reoxidation of the latter by air are carried out separately in two distinct reactors. Both processes are stoichiometric reactions and the vanadyl pyrophosphate functions as an oxygen carrier. Nonetheless the advantage of a higher selectivity, due to the separation of the product from the oxidant atmosphere, is balanced by the difficulties involved in moving huge volumes of solid between two different reactors. 

Since a decade ago, much research has been directed to mimic the oxygen carrier like Hb by synthesizing various modified porphinatoiron derivatives These synthetic porphinatoirons have been successful in oxygen-binding reversibly in organic solvents and solid states, but in aqueous media they have been irreversibly oxidized. Till recently, only Hb and Mb are known as oxygen carriers in aqueous media. 

CLC is most commonly studied and proposed for the combustion of methane (natural gas) streams. However, the process itself could be utilized for the conversion/com-bustion of any fuel, including liquids or solids, as long as it shows sufficient reactivity for oxidation with a solid oxidant (i.e., the oxygen carrier). 

The authors also propose a CFB reactor set-up for CLC operation with solid fuels (see Figure 4). A high velocity riser is suggested for the oxidizer, and a down-flow moving bed or bubbling fluidized bed for the reducer in which the solid fuel is fed. A low-velocity bubbling bed or turbulent fluidized bed thus acts as deep reduction reactor and separator for oxygen carriers from fly ash and unbumt carbon. In this... 

Leion H, Jemdal E, Steenari B-M, Hermansson S, Israelsson M, Jansson E, et al. Solid fuels in chemical-looping combustion using oxide scale and unprocessed iron ore as oxygen carriers. Fuel 2009 88 1945. 

GiameUo, E., Sojka, Z., Che, M., et al (1986). Spectroscopic study of superoxide species formed by low-temperature adsorption of oxygen onto cobalt oxide (CoO)-magnesium oxide solid solutions An example of synthetic heterogeneous oxygen carriers, J. Phys. Chem., 90, pp. 6084-6091. 

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