High purity H2 by sorption-enhanced chemical looping reforming of waste cooking oil in a packed bed reactor

High purity hydrogen (>95%) was produced at 600 °C and 1 atm by steam reforming of waste cooking oil at a molar steam to carbon ratio of 4 using chemical looping, a process that features redox cycles of a Ni catalyst with the in-situ carbonation/calcination of a CO2 sorbent (dolomite) in a packed bed reactor under alternated feedstreams of fuel–steam and air. The fuel and steam conversion were higher with the sorbent present than without it. Initially, the dolomite carbonation was very efficient (100%), and 98% purity hydrogen was produced, but the carbonation decreased to around 56% with a purity of 95% respectively in the following cycles. Reduction of the nickel catalyst occurred alongside steam reforming, water gas shift and carbonation, with H2 produced continuously under fuel–steam feeds. Catalyst and CO2-sorbent regeneration was observed, and long periods of autothermal operation within each cycle were demonstrated.