La‐hexaaluminate for synthesis gas generation by Chemical Looping Partial Oxidation of Methane Using CO 2 as Sole Oxidant

Chemical looping partial oxidation of methane using a sole CO 2 oxidant (CL‐POM‐CO 2 ) is an emerging technology for synthesis gas generation and CO 2 utilization, which is highly dependent on an oxygen carrier (OC). In this work, Fe‐substituted La‐hexaaluminate as the OC was found to exhibit good reactivity and stability during 50 periodic CH 4 /CO 2 redox cycles due to the formation of magnetoplumbite La‐hexaaluminate structure with the introduction of La. Deeper reduction for synthesis gas generation did not destroy the La‐hexaaluminate structure via a charge compensation mechanism, which increased CH 4 reactivity and further improved CO 2 utilization under subsequent re‐oxidation. In the La‐hexaaluminate structure, O 6 ‐Fe 3+ (Oh) was highly active for the total oxidation of methane, while O 5 ‐Fe 3+ (Tr) and O 4 ‐Fe 3+ (Th) selectively oxidized CH 4 to synthesis gas. The sole CO 2 oxidant only selectively recovered O 5 ‐Fe 3+ (Tr) and O 4 ‐Fe 3+ (Th), and thus is more favorable for improving synthesis gas selectivity than O 2 /air, which offers an attractive opportunity for CO 2 utilization. © 2017 American Institute of Chemical Engineers AIChE J , 64: 550–563, 2018