Separate H₂ and CO production from CH₄‐CO₂ cycling of Fe‐Ni

Abstract

Abstract CH 4 ‐CO 2 chemical looping is proposed for separate H 2 and CO production using nanostructured Fe‐Ni looping materials. The product streams are obtained by first feeding CH 4 , which decomposes to H 2 and carbon. The latter acts as reductant for the subsequent CO 2 feed, which together with Fe re‐oxidation yields CO. After 25 CH 4 ‐CO 2 cycles, 10Fe5Ni@Zr has a higher H 2 space–time yield than 10Fe0Ni@Zr ( vs. ), a 2.6 times higher CO yield () and lower deactivation. This improvement has two reasons: (i) CH 4 activation over Ni leading to cracking, (ii) product hydrogen causing deeper FeO reduction. Deactivation follows from accumulated carbon, non‐reactive for CO 2 . On Ni and Fe sites, carbon can be removed by lattice oxygen or CO 2 , yielding more CO compared to the theoretical value for Fe oxidation. However, carbon that migrates away from the metals requires oxygen for removal, which restores the activity of the Ni‐containing samples.