Ni-Fe-Al mixed oxide for combined dry reforming and decomposition of methane with CO2 utilization

Abstract

The chemical looping dry reforming of methane can be used to convert greenhouse gases into products with much desirable specification. However, developing an oxygen carrier with coke-tolerance and high oxygen exchange rate usually requires the use of rare-earth metals or lanthanides. In this study, by utilizing deposited surface carbon as a reaction intermediate rather than suppressing it, complete methane conversion was possible even with the earth-abundant metal oxide particles. To establish an optimized H2/CO ratio for the hydrocarbon synthesis, the CH4 feedstock was partially replaced with CO2. By itself, Ni-Al oxide exhibited deactivation due to the agglomeration arising from methane decomposition over the redox cycle. Fe-Al oxide had stable performance over cycles, but a sudden performance decline was observed when the amount of CO2 co-feeding exceeded a certain point. Incorporating Ni into the Fe-Al oxide was found to overcome these problems. The formation of a spinel phase with Fe alleviated the agglomeration, and enhanced CH4 activation under high CO2 partial pressure. The introduction of Ni also improved carbon gasification kinetics with CO2.