Development of a chemical-looping combustion reactor having porous honeycomb chamber and experimental validation by using NiO/NiAl2O4

Chemical-looping combustion (CLC) is already suggested as a promising approach for CO2 capture with a lower energy penalty. The appropriate reactor plays a paramount role in the application of CLC. Here, a fixed-bed honeycomb CLC reactor is proposed and its design methodology and procedure are given. The honeycomb chamber is a cylindrical monolithic block with a series of axial micro-channels. In this way, a sufficiently contact area and disturbance among reactants are provided for enhancing the reaction kinetics. The oxygen carrier not only consists of the supporting material of the honeycomb CLC reactor but also acts as reactants. A 10 kW prototype is manufactured by using NiO/NiAl2O4 as the oxygen carrier. The reactivity and redox stability of the honeycomb CLC reactor are experimentally examined by using the natural gas as the fuel gas. In the experiment, a CH4 conversion higher than 99% is obtained. By shortening the reduction time of the NiO/NiAl2O4, almost all the CH4 is converted into CO2 and CO emission is avoided. Additionally, the redox stability in the honeycomb CLC reactor is carried out for 150 h continuous operation. The test results show that the prototype reactor obtains a better reactivity and redox stability in contrast to the fixed-bed reactor without honeycomb chamber. Our results here would be expected to offer a new pathway for facilitating the progress of the CLC reactor.