Enhanced Hydrogenation of Levulinic Acid over Ordered Mesoporous Alumina‐Supported Catalysts: Elucidating the Effect of Fabrication Strategy

Abstract

In this work, three types of alumina‐supported bimetallic Ni−Cu catalysts [Ni−Cu/commercial non‐ordered mesoporous alumina (CMA), Ni−Cu/ordered MA (OMA), and Ni−Cu−OMA] were prepared via different fabrication strategies and investigated in the conversion of levulinic acid (LA) into γ‐valerolactone and 2‐methyltetrahydrofuran (2‐MTHF). This study employed characterization techniques and reactions to reveal the effects of the fabrication strategy on the activities of the catalysts. It was observed that the catalysts constructed on OM supports (Ni−Cu/OMA and Ni−Cu−OMA) displayed superior catalytic performance compared to those constructed on CM supports (Ni−Cu/CMA). Specifically, Ni−Cu−OMA, which was fabricated via the one‐pot evaporation‐induced self‐assembly strategy, exhibited the best catalytic performance, achieving a complete conversion of LA and a high selectivity of 73.0 % toward 2‐MTHF in a solvent‐free reaction environment. The promising activity of Ni−Cu−OMA was ascribed to the well‐dispersed active sites within the framework of the support, the enhanced metal‐support interaction, and the highly efficient exploitation of the synergistic effect between Ni and Cu. Detailed post‐characterization techniques were also employed to highlight the outstanding stability of Ni−Cu−OMA.

Interplay Between Metallicity and Acidity in the Hydrogenation of Levulinic Acid

“…43 The corrosive properties of LA and the liquid-phase reaction environment pose challenges in controlling metal leaching. 13,29 Particularly, the leaching of Cu and Ni−Co alloy formation surpasses the leaching of Ni and Co which is also observed in previous works. 33 With an increase in Co loading, it is anticipated that Co would form alloys with Ni, potentially hindering sintering and reducing metal leaching in the catalyst.…”

“…The samples exhibited different morphologies such as plates (P), spheres (S), spindles (SP), fibers (F), hollow flower spheres (HFS), and urchins (U). Figure S3 shows the 13 Across various alumina supports, the peak intensity weakens in the order HFS > p > U > SP, as depicted in Figure 2a.…”

“…Ni−Cu and Ni−Co combinations showed promising LA conversion and GVL selectivity of 99% and 83%, respectively. 12,13 Ni 2 Co 1 P achieved 100% LA conversion and 100% GVL yield, while ordered mesoporous alumina exhibited a 50.4% selectivity toward 2-MTHF. 14 Ni x Co y Mn z Al w -doped mesoporous silica catalysts were synthesized using a facile onepot procedure yielding 100% LA conversion and 96.3% PA yield.…”

Highly efficient Ni–Mn/SiO2catalyst for the selective hydrogenation of biomass-derived levulinic acid to γ-valerolactone under mild conditions

“…To obtain a high yield of the target product GVL, a high Ni loading, high H 2 pressure, high temperature and a long reaction time are needed. 18 In comparison, Ni-based bimetallic catalyst systems generally show higher activity than monometallic Ni catalysts. For instance, supported Ni-Re catalysts have shown high activity for the selective hydrogenation of carboxylic acids attributed to the promotion of oxophilic metal Re.…”

“…To obtain a high yield of the target product GVL, a high Ni loading, high H 2 pressure, high temperature and a long reaction time are needed. 18…”