Acid-Base Regulated Carbon-Encapsulated Nickel Nanocatalysts for Aqueous-Phase Upgrading of Ethanol to Higher Alcohols

The development of biomass-derived fuels presents a promising solution for mitigating the severe carbon emissions associated with fossil fuels. A key strategy involves the direct refining of aqueous-phase bioethanol into higher alcohols, which serves as key precursors for diesel blendstocks and biojet fuel. Herein, to enable the direct upgrading of aqueous ethanol, we developed carbon-encapsulated Ni nanocatalysts (Ni@C) with water resistance by pyrolyzing organic precursors under acid–base regulation. The catalytic coupling yields 46.5 C-mol % of higher alcohols, of which C4–C7 and C8–C16 alcohols constitutes 56.9% and 35.2% in product selectivity, respectively. Excellent miscibility with diesel is exhibited by C4–C7 alcohols across a wide range of blending ratios. Furthermore, hydrodeoxygenation of C8–C16 alcohols provides a direct route to biojet fuel. Results from experiment and characterization demonstrate that acid–base regulation effectively tunes the local electronic structure and carbon defects on the Ni@C nanocatalyst surface. The proposed approach allows for precise modulation of the dehydrogenation, aldol condensation, and hydrogenation steps in the Guerbet reaction pathway, which suppress carbon chain scission and enhance the yield of higher alcohols. Overall, this research offers a novel and feasible strategy to the sustainable synthesis of higher alcohols from bioethanol, producing products directly applicable as blending components and biojet fuel precursors.