Tailoring hierarchical GaMFI zeolite anchored Ni catalyst by indium for lignin derivatives hydrodeoxygenation

Abstract

Constructing highly active non-noble metal catalysts for hydrodeoxygenation reaction of lignin-derived compounds remains a challenge. Herein, the hierarchical Ga modified MFI zeolite (GaMFI) anchored bimetallic NiIn catalysts with Ni₄In and Ni₂In intermetallic compounds (IMCs) were built and employed for hydrodeoxygenation reaction of vanillin to 2-methoxy-4-methylphenol (MMP). By integrating various characterization data, it was demonstrated that doped In adjusted the acidity and distribution of Ni and Ni-In intermetallic compound (IMC). The NiIn2/GaMFI catalyst achieved an exceptional vanillin conversion of > 99 % and MMP selectivity of > 99 % under experiment conditions of 130 °C, 1.5 MPa H₂ and 4 h. Notablely, it exhibited the highest turnover frequency (TOF) value of 283.8 h⁻¹ among prepared NiIn catalysts, which was related to dispersed Ni and Ni₂In IMC dual sites that promoted the adsorption of H₂ and vanillin molecules confirmed by Density Functional Theory (DFT) calculation, while the abundance of acidic sites facilitated the activation and cleavage of C-O bond. Additionally, the NiIn2/GaMFI catalyst also demonstrated remarkable stability, maintaining high activity for at least 5 recycles, and showed outstanding universality for various lignin derivatives. These characteristics highlighted its significant potential in industrial application.