One-step hydrothermal synthesis of N-doped biomass-derived carbon-supported Ni catalysts for ethanol dehydrogenative coupling

Coupling of bioethanol to obtain higher–chain alcohols as biofuels is a promising strategy to address the current energy crisis and achieving carbon neutrality. However, controlling the catalyst’s spatial structure to attain high yields and selectivity of higher-chain alcohols remains a significant challenge. In this study, alkali lignin and melamine were used as the carbon and nitrogen sources, respectively, to synthesize nitrogen‑doped, lignin‑derived carbon‑coated nickel catalysts (Ni@NC) with high nitrogen content and a large specific surface area through hydrothermal modification and in situ pyrolysis. The effects of hydrothermal duration, the molar ratio of metal to lignin, the mass ratio of nitrogen source to lignin, and reaction temperature on catalytic performance was systematic investigated. Under optimal conditions (8 h hydrothermal treatment, Ni/AL 20:1), the Ni@NC catalyst exhibited 58.8 % ethanol conversion, 51.2 % higher‑alcohol yield, and 93.6 % selectivity. Hydrothermal nitrogen doping introduced abundant nitrogen-containing functional groups, which enhanced nickel anchoring sites and reinforced the catalyst–support interaction. During pyrolysis, melamine decomposition and lignin condensation facilitated the formation of high-surface-area, porous, wrinkled carbon spheres, promoting active site exposure and improving mass transfer. This work provides a promising pathway for converting bioethanol into higher alcohols, with significant potential for industrial-scale production.