Reduction and Oxidation Kinetics of a Copper-Based Oxygen Carrier Prepared by Impregnation for Chemical-Looping Combustion

作者：Francisco Garcı́a-Labiano, Luis F. de Diego, Juan Adánez, Alberto Abad, Pilar Gayán · 发表于：Industrial & Engineering Chemistry Research · 年份：2004 · DOI：10.1021/ie0493311 · 被引用次数：248 · 研究领域：Chemical Looping and Thermochemical Processes、Industrial Gas Emission Control、Nuclear Materials and Properties

The kinetics of reduction with CH 4, H 2, and CO and oxidation with O 2 of a Cu-based oxygen carrier prepared by impregnation on alumina to be used in a chemical-looping combustion (CLC) system have been determined in a thermogravimetric analyzer. The oxygen carrier exhibited high reactivity in both reduction and oxidation with times for complete conversion lower than 40 s at 1073 K and 5−70 vol % of the fuel gas and 5−21 vol % of O 2 . The analysis of the sample carried out by scanning electron microscopy using energy-dispersive X-ray and chemisorption showed that the CuO was well dispersed in the porous surface of the alumina matrix and a uniform thin layer on the porous surface was considered. The shrinking-core model for platelike geometry of the reacting surface was used for the kinetic determination, in which the chemical reaction controlled the global reaction rate. No effect of the gas products (H 2 O and CO 2 ) on the reaction rate was detected. The reaction order depended on the fuel gas, and values of 0.4, 0.6, and 0.8 were found for CH 4, H 2, and CO, respectively. The order of the oxidation reaction was 1. The activation energies for the reduction and oxidation reactions varied between 14 and 60 kJ mol -1 . The reactivity data together with the operating variables were used to calculate some design parameters for a CLC system. It was found that the total solid inventory and the recirculation rate are linked. To optimize both parameters, conversion variations of t...