Fixed Bed Reactor Validation of a Mayenite Based Combined Calcium–Copper Material for Hydrogen Production through Ca–Cu Looping

Abstract

For the first time, a mayenite based material combining calcium and copper (18.0/37.6/44.4 estimated active wt % CaO/CuO/Ca12Al14O33, CuO/CaO = 2.1 [wt/wt]) has been subjected to three full calcium–copper chemical looping combustion (Ca–Cu Looping) cycles in a fixed bed reactor (70.0 g of combined material and 3.5 g of 18.0 wt % Ni/Al2O3 reforming catalyst), demonstrating the feasibility of a combined materials approach to hydrogen production through Ca–Cu Looping. Combined materials were characterized by helium pycnometry, mercury intrusion, nitrogen adsorption, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, and energy dispersive X-ray diffraction before and after reactor testing. A carbon dioxide capture capacity of 14.6–15.0 g CO2/100 g (640–660 °C, 1.0 MPa, 2.5 kgCH4 kgcat–1 h–1), full oxidation, and expected calcination efficiencies (51–64%) were obtained. Combined material performance is comparable to that of segregated materials previously tested in the same experimental rig. Process intensification of Ca–Cu Looping through combined materials development is promising.