Study of the sorption property of copper oxygen carrier used for chemical looping air separation

Abstract

Chemical looping air separation used in the oxy-fuel combustion system resolves the oxygen source. Oxygen carrier releases oxygen in flue gas atmosphere and absorbs oxygen in air atmosphere. One of the most important properties is the sorption of the decomposed oxygen carrier. Aiming at investigating the sorption property in detailed, copper oxygen carrier with 40 mass% MgAl2O4 as inert binder was prepared. Thermodynamic calculations and the physical and chemical characterizations of the CuO–MgAl2O4 were carried out. The sorption property was investigated in the TG and fixed-bed reactor. The active phases of copper oxides do not react with MgAl2O4 during the preparation and reaction processes. The adding of MgAl2O4 hinders the grains growth of copper oxides. The decomposed oxygen carrier can react with oxygen when temperature is higher than 400 °C. The thermodynamic results indicate the highest sorption temperature should be lower than 1,027 °C in air atmosphere. Indeed, the sorption is not complete when temperature is 1,010 °C in TG experiment. Pressurized oxidation reactor is conducive to the oxidation of decomposed oxygen carrier at high temperature. The decomposed oxygen carrier has strong oxygen sorption capability. Low temperature is conducive to the sorption process. In all the gas flows and oxygen concentrations tested, the outlet oxygen concentrations all were kept in a low level. The effect of particle size on the sorption rate is little, and big particle size of oxygen carrier can be selected to reduce the pressure drop of the bed.