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The solid metal oxide oxygen carrier is then circulated between these two reactors. That is the reducer and the oxidizer/combustor are connected in a solids circulatory loop, while the gaseous reactants and products from each of the two reactors are isolated by the gas seals between the reactors.
Since the metal oxide is a solid structure, both reactions must be done in the same reactor, which leads to a discontinuous production process, carrying out one step after the other. To avoid this stops in the production time, multiple reactors can be arranged to approximate a continuous production process.
Chemical looping combustion (CLC) uses two or more reactions to perform the oxidation of hydrocarbon-based fuels. In its simplest form, an oxygen-carrying species (normally a metal) is first oxidized in the air forming an oxide. This oxide is then reduced using a hydrocarbon as a reducer in a second reaction.
A solid oxide electrolyser cell (SOEC) is a solid oxide fuel cell set in regenerative mode for the electrolysis of water with a solid oxide, or ceramic, electrolyte to produce oxygen and hydrogen gas. [53] SOECs can also be used to do electrolysis of CO 2 to produce CO and oxygen [54] or even co-electrolysis of water and CO 2 to produce syngas ...
Carbothermal reactions produce carbon monoxide (CO) and sometimes carbon dioxide (CO 2). The facility of these conversions is attributable to the entropy of reaction: two solids, the metal oxide (and flux) and carbon, are converted to a new solid (metal) and a gas (CO x ), the latter having high entropy.
In the temperature ranges commonly used, the metal and the oxide are in a condensed state (solid or liquid), and oxygen is a gas with a much larger molar entropy. For the oxidation of each metal, the dominant contribution to the entropy change (ΔS) is the removal of 1 ⁄ 2 mol O 2, so that ΔS is negative and roughly equal for all metals.
Ostwald ripening is a phenomenon observed in solid solutions and liquid sols that involves the change of an inhomogeneous structure over time, in that small crystals or sol particles first dissolve and then redeposit onto larger crystals or sol particles.
The oxide particles instead are stable in the matrix, which helps prevent creep. Particle stability implies little dimensional change, embrittlement, effects on properties, stable particle spacing, and general resistance to change at high temperatures. [5] Since the oxide particles are incoherent, dislocations can only overcome the particles by ...