Incorporating Mg into Al-based supports to modulate metal-support interactions for enhanced H2 productivity and selectivity in Ni-catalyzed aqueous-phase reforming

Abstract

Aqueous-phase reforming (APR) of biomass-derived oxygenates provides a sustainable route for hydrogen production. Owing to their multifunctionality, Ni-based catalysts have been widely studied; however, these catalysts are still limited by methanation side reaction that decreases H 2 selectivity and agglomeration that reduces activity. Herein, we demonstrate that these issues can be tackled by regulating the metal-support interaction (MSI) in the supported Ni catalysts. Specifically, Mg is incorporated into Al-based supports to precisely modulate the MSI between Ni and Al-based support to enhance selective hydrogen production from APR of ethylene glycol. A volcano-type dependence of H 2 productivity on Mg content is observed, with an optimal Mg/Al ratio of 1:3 achieving an H 2 productivity of 4.43 mmol/g Ni /min, approximately twofold higher than that of Ni/Al 2 O 3 (2.20 mmol/g Ni /min), while completely suppressing methanation. Complementary characterizations and theoretical calculations reveal that Mg strengthens MSI, promoting the dispersion of Ni species and partially depleting the electron density of Ni, which increases the density of active sites to enhance apparent activity and suppresses hydrogen-consuming side reactions. However, excessive Mg induces overly strong MSI, stabilizing Ni in an electron-deficient and poorly reducible state, thereby inhibiting decarbonylative C–C bond cleavage and drastically reducing activity. This work demonstrates MSI modulation as an effective strategy to balance geometric and electronic effects in Ni catalysts for efficient hydrogen production via APR.