Experimental Investigation On Characteristic Of Compound Cu-Based Oxygen Carrier In Chemical-Looping With Oxygen Uncoupling

Coal resource is rich in China, which determines its energy consumption structure is dominated by coal. In 2014, the Chinese government promises the CO2 emission will reach its peak around 2030 even earlier. Thus, it owns important research significance to exploit emission reduction and capture technology for CO2, produced by coal fossil fuel combustion. Chemical-looping combustion(CLC) is a new combustion technology, which can separate and capture CO2 simply with low energy consumption, and there is no NOx in the combustion process. Oxygen carrier is a key to CLC, and Cu-based oxygen carrier was studied because of its good activity and high oxygen-carrying capacity.First, three kinds of Cu-based oxygen carriers Cu6Si4?Cu6Ti4 and Cu6Al4 were prepared through mechanical blending method, by using Al2O3,SiO2 and TiO2 as inert carriers. Their cycling performances were researched, SEM and XRD were applied to characterize the change of microstructure and phase composition. With better performance, Cu6Si4 and Cu6Ti4 were selected to conduct CLC with coal in fixed bed reactor. Then, two series of CuO/MgO and CuO/NiO compound oxygen carriers were prepared through impregnation method. They were conducted CLC with coal, 20-times releasing and absorbing oxygen cycles to research their cycling performance, oxygen-carrying capacity, rates of redox reactions. SEM and XRD were applied to characterize the change of microstructure and phase composition. In addition, the two series of compound oxygen carriers were conducted CLC with coal in fixed bed reactor. Finally, compound Cu-based oxygen carrier particles were prepared through squeezing+pelletizing method. They were conductd cold test and thermal cycling in a fluidized bed to study their abrasion resistance,cycling performance and reactivity.SEM was applied to study the anti-sintering performance of these oxygen carrier particles.The research results show that: CuO sinters worse and its reactivity decreases with the increase of cycles, and higher temperature make Cu-based oxygen carriers sinter worse. The addition of inert support can improve the anti-sintering performance and cycling performances, Ti O2 is more suitable than Si O2 as the inert support for CuO.The experimental results of compound Cu-based oxygen carriers show that: the overall performance of Cu6Mg1Ti3 is the best among the serie of CuO/MgO compound oxygen carriers, which means TiO2 is more suitable than SiO2 and ZrO2 as the inert support for CuO/MgO; the overall performance of Cu6Ni1Zr3 is the best among the serie of CuO/NiO compound oxygen carriers, which means ZrO2 is more suitable than SiO2 and TiO2 as the inert support for CuO/NiO.The experimental results of compound Cu-based oxygen carrier particles show that: the abrasion resistance of Cu6Ni1Zr3-K(30%ZrO2) is better than Cu6Ni3Zr1-K(10% ZrO2). In the early cycle, the mass decay rate of Cu6Mg3Ti1-K is the fast, the content of TiO2 in Cu6Mg1Ti3-K is higher than that in Cu6Ni3Zr1-K, and TiO2 can improve the abrasion resistance of compound Cu-based oxygen carriers. The abrasion resistance of these oxygen carrier particles ranks as: Cu6Ni1Zr3-K>Cu6Mg1Ti3-K>Cu6Mg3Ti1-K> Cu6Ni3Zr1-K. According to overall trends, the four kinds of oxygen carrier particles sintered in the five cycles, which lead to the decline of oxygen-carrying capacity. The reactivity of these oxygen carrier particles ranks as: Cu6Mg3Ti1-K>Cu6Ni3Zr1-K> Cu6Ni1Zr3-K> Cu6Mg1Ti3-K.