Analysis of oxygen releasing rate of Cu-based oxygen carrier in N2–O2 atmosphere

Abstract

Technologies of chemical looping with oxygen uncoupling (CLOU) and chemical looping air separation (CLAS) all depend on oxygen releasing property of oxygen carriers used. The oxygen releasing rate of oxygen carrier is controlled by heat and mass transfers as well as chemical reaction rate. In this work, Cu/Zr oxygen carrier was prepared. X-ray diffraction, scanning electron microscopy, and surface area analyzer (BET) were used to characterize the oxygen carrier before and after cyclic experiment. The effects of particle size, gas flow, reaction temperature, oxygen concentration, and cyclic number on oxygen releasing rate were investigated on the thermogravimetric analyzer. The results show that the oxygen releasing rate increases significantly with increasing of temperature. The starting temperatures of reduction reactions shift to high level as oxygen concentrations increase. The effects of particle size and gas flow are little. The oxygen releasing rates during cyclic experiment are almost the same. The main phases in fresh and reoxidized particles are CuO and ZrO2, and in reduced particles are Cu2O and ZrO2. The surfaces of reacted particles have no obvious agglomeration. The oxygen releasing rate is controlled by chemical reaction of the particle. The results obtained are essential to the design of CLOU and CLAS systems.