Solid oxygen carrier

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 ... 

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. 

In all previous chemical looping-based concepts, the solid oxygen carrier is in the form of (in some designs circulated and in other designs stationary) particles. 

The law was stated in this form by J. P. Joule in 1844 it is usually referred to as AVoestyn s law (1848). It shows that the carriers of heat in a solid compound are not the molecules of the latter, but the atoms of its constituent elements. Joule s law enables one to calculate the molecular heats of compounds from the atomic heats of their elements, and the atomic heats of elements in the solid state when the latter are not readily directly accessible (solid oxygen, from c(CaC03) — c-(Ca) — c(C) = 3c(0), or 100 X 0 203 — 6 4 — P8 = 3 X 4 0). 

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. 

In spite of the many modern techniques available to the chemist, the known chemistry of polynuclear cobalt (III) complexes is essentially that deduced by Werner 60 years ago. Since his work, no new polynuclear cobalt complexes have been prepared and characterized and no new reactions uncovered. Modem work in this area is being aimed at attaining a better understanding of the electronic structures inherent in polynuclear ions, which would be of value in a variety of active fields. The chemistry of polynuclear complexes is important in such new areas as synthetic oxygen carriers, electron transfer reactions, and transition metal catalysis. The fact that these new investigations are solidly based on Werner s pioneer investigations testifies to the genius with which he opened up a new area of coordination chemistry, with only the simple chemical techniques available to him. His work in the area of polynuclear cobalt(III) ammine complexes should continue to serve as a model of solid research for some time to come. 

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