Research Of A Cu-based Oxygen Carrier Prepared By Self-assembly Template Combustion Method For The Chemical-looping Processes

Due to the worldwide use of fossil fuels, the green house effect has become increasingly serious for the large-scale emission of CO2. In China, 70% of the energy consumption is provided by coal. Therefore, it leads to the increasing pressure of CO2 emission reduction. CO2 capture and storage?CCS? is regarded as the important means of CO2 emission reduction. Chemical Looping Combustion?CLC? is a novel combustion technology that can be used in CCS. The process uses a metal oxide as oxygen carrier?OC?, in the fuel reactor the OC can be reduced to pure metal or metal suboxide; In the air reactor the OC can be oxidized by oxygen in air. The directly contact of fuel and air is avoided by the cycling of OC between the the two reactors, so we can capture very pure CO2 with low cost and achieve the clean and effective utilization of coal.In CLC technology the OC plays a very important role, in our recent work, periodical density functional theory?DFT? is used to research the oxygen decomposition mechanisms of Cu-based OC in CLOU process, including the diffusion and migration of lattice oxygen in the OC. On the micro level, we researched the effect of adding several typical inert materials, and then provide guidance to rational design and optimize the preparation of OC. On this basis, we use self-assembly template combustion synthesis method prepared a core-shell Cu O@TiO2-Al₂O₃ hierarchical structure as an oxygen carrier for the chemical-looping processes, this kind of OC has the property of high oxygen capacity and high reactivity.Firstly, we research the reaction process of Cu O@TiO2-Al₂O₃ with H2 on a TGA, and compared with a high performance OC material Cu O/Cu Al2O4, in 50 cycles the new OC showed great reactivity and stability. In the oxidation process, we found the oxidation pathway was Cu?Cu2O?Cu O, at first the Cu was oxidized to Cu2 O, and then the Cu2 O was oxidized to Cu O, in this process the oxygen uptake of Cu2 O was controlled by oxygen partial pressure and the inert carrier.Secondly, in a batch fluidized-bed reactor, we investigated the CLC process of CuO@TiO₂-Al₂O₃ with gas fuel and the CLOU performance with three typical coals of different ranks. In the CLC process, it was found that with the increase of temperature, the reaction rate was promoted, and Cu O@TiO2-Al₂O₃ sample showed a higher reactivity, in 10 cycles the reduction conversion rate remained stable. In the CLOU experiments, it was also found that an increase in the temperature and a decrease in the coal rank both had an acceleration effect on the reaction rate of coal. The coal combustion process could be divided into two stages, the combustion of volatiles and the combustion of coal char. The rate-limiting step in CLOU process was the reaction between gaseous oxygen and coal char and the OC particles was easily to occur agglomeration and sintering with lignite at high temperatures. In the 20 cycles of CuO@TiO₂-Al₂O₃ with Gaoping coal, the OC showed great reactivity and stability.At last we researched the effect of temperature and gas flow in Chemical looping air separation process of Cu O@TiO2-Al₂O₃ on the batch fluidized-bed reactor and optimized the experiment parameters, according to the optimization scheme, a 10 h oxygen production experiment was conducted in a parallel fluidized bed reactor system, the O2 concentration of reactor outlet remained above 20%, and the average flow rate of O2 reached to 45ml·min-1, realized the continuous production of high concentration oxygen, showing the potential to be used in industry applications.