Study of a Cu-Based Oxygen Carrier Based on a Chemical Looping Combustion Process

摘要

On the basis of a chemical looping combustion (CLC) process with adding a step of CH4 steam reforming, the influences of the preparation method, inert support of SiO2 or Al2O3, Ni component, particle size, and gas hourly space velocity (GHSV) on the redox performance of a Cu-based oxygen carrier (OC) were investigated. Results showed that the OC prepared with impregnation was able to react completely with H-2 in reduction or O-2 in oxidation but had a relatively low oxygen content ratio (R-o) because of the limitation from saturation loading of an active component. In contrast, the OC prepared with mechanical mixing had a high R-o as well as high reactivity. The inert support was able to inhibit the sintering of the OC through dispersing the active component. Methanation and reverse CO-water shift reactions occurred in the reduction step, where metallic Cu played the role of a catalyst. The utilization ratios of the OC for both reduction and oxidation increased as the size of the active component particle decreased and mildly decreased with decreasing the size of the OC particle. However, as the size of the OC particle approached the size of the inert support particle, the performance of the OC dropped.