Thermodynamically balanced conversions of CH4 and CO2 by dual-phase NiFe on Al2O3 catalysts for highly efficient dry reforming

Dry reforming of methane (DRM) has received significant attention as a sustainable strategy to utilize representative greenhouse gases (GHGs), CO 2 and CH 4 , to produce valuable syngas, H 2 and CO. Cost-effective NiFe-based catalysts are attractive due to the superior CH 4 dissociation capability of Ni and the exceptional CO 2 activation ability of Fe. However, Fe, which activates CH 4 dissociation at high temperatures above 700 °C, causes carbon deposition due to its poor carbon removal characteristics and Fe oxidation resulting from unbalanced reaction pathways from CO 2 and CH 4 reactants. Herein, this study demonstrates a rational dual-phase structure catalyst design strategy comprising Ni with excellent CO 2 conversion and Ni 1 Fe 1 alloy with superior CH 4 conversion, which improves thermal stability because of the prompt reaction between oxygen adatoms and carbonaceous intermediates using neutral-Al 2 O 3 . Ni 3 Fe 5 /Al 2 O 3 achieves stable operation at 800 °C for 570 h with high average conversions of 92% for both CO 2 and CH 4 with a minimal difference of 3%. This thermodynamically balanced conversion inhibits carbon deposition and prevents Fe oxidation under high-temperature conditions. These findings demonstrate that stable operation is achieved through the partial dehydrogenation of CH 4 by abundant dual-phase active sites, which react vigorously with oxygen species via neutral support.