Trivalent cation (Al, Ga, In) modulation of LDH-derived Cu-Co catalysts for higher alcohol synthesis from syngas

M 3+ controls phase evolution: Al/Ga form Cu-Co alloy; In 3+ leads to CuIn, CoIn 2 , In 2 O 3 separation. • Surface hydroxyls and bridged CO provide dual CHₓ sources for C 2+ OH formation. • Medium-strength basic sites and Cu + fraction, not total basicity, govern C 2+ OH selectivity. • Smaller M 3+ radius (Al 3+ ) strengthens metal-support interaction, enhancing dispersion and performance. The modulation of trivalent cations in layered double hydroxide (LDH)-derived catalysts provides an effective strategy for tuning the multifunctional active sites for higher alcohol synthesis. In this study, a series of layered CuCoM catalysts (M = Al, Ga, In) was synthesized via alkaline co-precipitation and evaluated for higher alcohols synthesis via CO hydrogenation. The results demonstrate that the introduction of M 3 + is essential for constructing the LDH precursor structure and significantly influences the phase evolution, morphology, textural properties, reducibility, surface basicity, and chemical states of the catalysts. Among the catalysts tested, CuCoAl exhibited the best overall performance, achieving a CO conversion of 35.60%, an ethanol selectivity of 39.97%, and a C 2 + alcohols selectivity of 73.47%. Structural characterization revealed that CuCoAl had the highest specific surface area and the most uniform dispersion of Cu and Co species, which favored the exposure of accessible active sites. CO 2 -TPD, XPS, and in situ DRIFTS results further indicated that CuCoAl contained abundant surface hydroxyl groups and a higher fraction of Cu + , which promoted the formation of formate species, facilitated non-dissociative CO insertion, and enhanced CH x generation through both formate hydrogenation and bridged CO dissociation on Co sites. The superior catalytic performance of CuCoAl is thus attributed to the synergistic effect of highly dispersed Cu-Co active sites, abundant surface hydroxyl groups, and optimized Cu + /Co interfacial functionalities. This study provides mechanistic insights into trivalent-cation regulation in LDH-derived CuCo catalysts and offers a rational strategy for the design of efficient catalysts for higher alcohol synthesis from syngas. Download: Download high-res image (174KB) Download: Download full-size image