Constructing Highly Hydrophobic NiSn-SDB Catalyst Via Facile Physical Mixing for Aqueous Ethanol Upgrading to C6 + Alcohols

Abstract

Converting aqueous ethanol into higher alcohols (HAs) serves as a promising and green pathway for synthesizing valuable chemicals and sustainable fuels from renewable resources. Despite its broad potential, direct carbon chain growth of ethanol toward value-add C₆₊ HAs remains a great challenge. In this study, we developed a novel highly hydrophobic NiSn-SDB catalyst utilizing a straightforward physical ball-milling technique. This approach effectively modulates the catalyst's surface hydrophobicity, enhancing the adsorption of alcohol molecules. The optimized NiSn-SDB_1/0.5 catalyst achieved an outstanding catalytic performance with C₆₊ HAs selectivity of 70.7% at 86.4% ethanol conversion rate. Notably, the catalyst demonstrated excellent kinetic efficiency, securing 67.1% ethanol conversion and 68.7% C₆₊ HAs selectivity within only 1-h reaction. The crucial role of hydrophobic SDB modifier was demonstrated, which enhances the adsorption of HAs molecules, thus promoting the cross coupling process to yield C₆₊ HAs. This research presents a highly effective and practical strategy for engineering robust, hydrophobic-modified catalyst for direct aqueous ethanol coupling.

Graphical Abstract

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Efficiently upgrading aqueous bio-ethanol into C₆₊ higher alcohols (sustainable aviation fuel precursors) is highly desirable but severely hindered by mass-transfer resistances and premature intermediate desorption. Herein, we innovatively developed a NiSn-SDB composite catalyst featuring a physical hydrophobic microenvironment. Acting as a microscopic "molecular trap," the SDB polymer grants the catalyst exceptional interfacial tracking capability and robust spatial confinement, successfully overcoming the thermodynamic bottleneck of intermediate desorption. This strategy delivers outstanding performance for C₆₊ alcohol synthesis, offering novel insights into breaking the kinetic limitations of continuous carbon chain propagation via surface microenvironment engineering.