Nd-Modulated Ni Catalysts with Bifunctional C/TiO2 Interfaces for Selective Upgrading of Aqueous Ethanol to Higher Alcohols

Abstract

The Guerbet coupling of aqueous bioethanol to long-chain higher alcohols offers a sustainable pathway to advanced biofuels and fine chemicals, yet conventional Ni catalysts suffer from C–C bond scission, which generates C1 gaseous byproducts and lowers carbon utilization efficiency. Herein, we rationally fabricate a NiNd@C–TiO2 composite catalyst integrating electronic modulation and interfacial engineering to suppress C–C cleavage and drive selective carbon chain elongation. Nd doping reconstructs the electronic configuration of Ni sites, weakening excessive adsorption of atomic hydrogen and acetaldehyde intermediates, as verified by H2-TPD and CH3CHO-TPD. Such electronic regulation effectively restrains aldehyde decomposition and methanation. Meanwhile, the hybrid C/TiO2 support establishes a hydrophilic–lipophilic bifunctional interface, facilitating mass transfer at the oil–water interface. Under optimized conditions (210 °C, 6 h), the NiNd@C–TiO2 catalyst delivers an ethanol conversion of 63.3% and a C4+ alcohols yield of 40.8% with suppressed gaseous byproduct selectivity. Moreover, the catalyst retains remarkable catalytic activity after ten consecutive recycling cycles, demonstrating excellent hydrothermal stability. This work demonstrates that synergistic electronic and interfacial modulation effectively redirects the reaction network from C–C cleavage toward dehydrogenation-condensation-hydrogenation, providing a promising non-noble metal catalyst for bioethanol upgrading.