A series of Cu/Co/Mn/Al catalysts derived from hydrotalcite precursors with different Cu/Co molar ratios (0, 0.1, 0.5, 1.0, and 2.0) were prepared and used for the synthesis of higher alcohols from syngas. N2 physical adsorption desorption, inductively coupled plasma atomic
emission spectrometry (ICP-AES), X-ray diffraction (XRD), scanning electron microscopy (SEM), hydrogen temperature-programmed reduction (H2-TPR), thermogravimetry (TG), and high-resolution transmission electron microscopy (HRTEM) techniques were employed to investigate the physical
and chemical properties of the Cu/Co/Mn/Al catalysts. The results show that the optimum Cu content can increase specific surface area, improve reducibility, and form regular layered structure to provide more uniform distribution of active sites, thereby enhancing catalytic activity and alcohol
selectivity. When the Cu/Co molar ratio was 0.5, the yield of alcohol and the alcohol selectivity reached the maximum values of 0.071 g·g-1·h-1 and 35.9%, respectively.
Using a citrate-assisted liquid phase co-precipitation method, a CuCoAl-LDH composite nanomaterial was successfully synthesized in situ on rGO and applied to alcohol synthesis for the first time. Structural characterization and morphological observations indicate that the hybrid material consists of hexagonal LDH nanosheets that are vertically aligned, crossed and densely distributed on the rGO surface. The graphene support significantly promoted the dispersion of LDH and prevented strong interlayer stacking during LDH crystal growth. After optimization of the Co/Cu ratio, the Cu 2 Co 1 /Al 2 O 3 /rGO catalyst exhibited a total alcohol selectivity of 60 %, of which 82 % were C 2+ alcohols, and no deactivation was observed after 100 h of reaction. The addition of the graphene support significantly reduced the particle size of the Cu-Co alloy on the catalyst surface, and the particles were highly dispersed on both the Al 2 O 3 matrix and the rGO surface. This dispersion facilitated strong interactions between the Cu-Co alloy particles, while the high thermal conductivity of graphene effectively suppressed the formation of hotspots. In addition, the well-ordered three-dimensional nanosheet structure of the LDH precursor provides a large specific surface area and highly uniformly dispersed active centers. This structure not only promotes the formation of bridge adsorption sites with high CO dissociation ability, which balances multiple bonding and bridge CO adsorption, but also significantly increases the probability of CO insertion, thereby enhancing the performance of HAS. This study provides an effective method for the preparation of LDH/rGO composites, demonstrating their broad potential application prospects.
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