Oxygen Uncoupling And Combustion Reactive Properties Of Cu-based Oxygen Carriers

Owing to the irreversible and disastrous global warming for the greenhouse effect, the world is working on the new combustion technique to control and recycle CO2. The chemical-looping with oxygen uncoupling (CLOU) process is an advanced technology that allows the combustion of solid fuels with inherent CO2 separation. The oxygen for combustion is released from the oxygen carrier and combusts with solid fuel in the reactor. This technology has higher combustion efficiency and low energy penalty for the combustion of solid fuel and high CO2 capture proportion. At the same time, it can efficiently control the emission of harmful gases, such as nitrogen compounds.By the using of the Aspen Plus, the chemical-looping with oxygen uncoupling process and traditional coal combustion process are set up. With the same boundary conditions, the outlet gases and system energy analysis and exergy analysis are compared. The results show that the chemical-looping with oxygen uncoupling process can not only reach the aim to produce the high concentration of CO2, but also enhance the system energy and exergy efficiencies with compared to the traditional coal combustion.Under the reference of the existed worldwide research results, the Cu-based oxygen carriers with the inert supports of ZrO2 or Y2O3 are prepared by the sol-gel method and the impregnation with graphite method for the use by CLOU. Both the physical and chemical characterizations are carried out. The crystallite phases of the oxygen carriers are determined by the XRD and SEM analyses. And the reaction rates for oxygen generation and the redox behavior stability are carried out in a TGA system. Through the XRD process, all the oxygen carriers are consisted of the CuO and the corresponding insert supports. The oxygen carriers can reach the demand of the following experiments. The CuO/ZrO2 particles by the sol-gel method perform considerably higher conversion rate than other metal oxides and preparing methods discussed in this work, for the fastest reaction rate in the higher temperature and taking a good help of the oxygen equilibrium partial pressure of CuO. While, the CuO/ZrO2 particles by the impregnation with graphite method have better circulation stability during the redox processes for the high oxygen release after circulations. Through the SEM process, the main reason for the reduction of the oxygen release of the oxygen carriers is the agglomeration behavior.The experiment what the combustion of the oxygen carriers and the coal is conducted on the fixed bed equipment. In order to determine the conversion rate of the released oxygen by carriers, the concentration of outlet gases is detected by the gas chromatograph. The result shows that the CuO/ZrO2 particles by the sol-gel method can release the most H2 and CO2, at the same time it can achieve the highest conversion rate 72.61%. As a result, the preparation method of the sol-gel and the insert supports of ZrO2 could promote the property of the oxygen releasing of the oxygen carriers.