Structure regulation of lignin-derived N-doped carbon-supported Ni catalyst for efficient upgrading of ethanol to higher alcohols

The selective conversion of biomass-derived ethanol into higher alcohols is a desirable but challenging process for the efficient production of value-added chemicals from alternative carbon sources. However, the current catalysts used in ethanol coupling exhibit low conversion rates and yields towards the formation of higher alcohols, necessitating significant improvements in their efficiency for practical applications. In this work, a lignin-derived N-doped carbon- supported Ni catalyst for ethanol coupling was designed and synthesized. The Ni@NC catalyst, synthesized using diethylenetriamine as the nitrogen source with a mass ratio of nitrogen source to lignin of 2:1 and a molar ratio of metal to lignin of 20:1, demonstrated excellent performance, with an ethanol conversion rate of 81.1 % and a yield of C4+ alcohols reaching 35.3 %. Experimental results and density functional theory (DFT) calculations suggest that nitrogen-doped lignin, in appropriate quantities, along with the metal active component, forms a Ni-N-C structure that controls charge redistribution between the support and the Ni catalyst. This structure hinders the interaction of reaction intermediates and inhibits the production of by-products in the decomposition reaction, resulting in a higher yield of C4+ alcohols. This study presents a more cost-effective and efficient approach for developing ethanol-coupling catalysts and holds promise for expanding the utility of lignin-derived catalysts.