High purity H_2 by sorption-enhanced chemical looping reforming of waste cooking oil in a packed bed reactor

摘要

High purity hydrogen (>95%) was produced at 600°C and 1atm 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 CO_2 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 H_2 produced continuously under fuel-steam feeds. Catalyst and CO_2-sorbent regeneration was observed, and long periods of autothermal operation within each cycle were demonstrated.