Chemical Looping Reforming of Glycerol for Continuous H2 Production by Moving-Bed Reactors: Simulation and Experiment

Chemical looping reforming of biomass is a promising avenue for hydrogen generation. Both the design of reactor configurations and the screening of oxygen carriers represent major challenges in chemical looping technologies. Here, we synthesize three oxygen carriers (referred to as Ni-Al, NiW-Al, and W-Al) by a continuous coprecipitation method and first test them in a fixed-bed reactor. The NiW-Al showed the highest coke resistance, reducibility, and glycerol conversion. We employ an Ellingham diagram to explain the superior performance of the NiW-Al and screen operational temperatures from the standpoint of thermodynamics. Then, using the NiW-Al oxygen carriers, we investigate the effect of Ni-to-glycerol ratio, fuel reactor temperature, and steam-to-glycerol ratio in moving-bed reactors. Establishing two sets of five-stage equilibrium models in Aspen Plus, we compare the experimental results with simulations, discovering good agreement with each other. An isothermal and coke-free operational window was optimized at a fuel reactor temperature of 650 degrees C, a Ni-to-glycerol ratio of 0.9, and a steam-to-glycerol ratio of 4.5, achieving an average H-2 yield of 1.5 mol-H-2/mol-C. This work highlights the promise of combining moving-bed reactors with oxygen carriers with high oxygen storage capacity to utilize biomass by chemical looping reforming for continuous H-2 generation.