Synergetic catalysis of bimetallic copper–cobalt nanosheets for direct synthesis of ethanol and higher alcohols from syngas

Abstract

A series of bimetallic CuCo catalysts were synthesized through different preparation strategies and evaluated for ethanol and higher alcohol synthesis from syngas. The optimal CuCo catalyst, which has a Cu/Co ratio of 2/1, was derived from introducing Cu and Co elements at the same time into the layered double hydroxide (LDH) precursor. The uniformly dispersed CuCo catalyst with a small particle size exhibited markedly improved catalytic activity and ethanol selectivity (34.3%) with a narrow alcohol distribution of C₁–C₃ mixed alcohols (90.6%). As revealed by HAADF-STEM and in situ FTIR spectroscopy, the superior mixing of Cu and Co species exhibited a higher probability of CO bound in bridging geometries to neighboring metallic Co atoms, which was beneficial to enhance the amount of CH_x intermediates. Moreover, the optimal CuCo catalyst exhibited a large specific surface area and an enrichment of copper. Meanwhile, temperature programmed surface reaction (TPSR) confirmed the weak hydrogenation probability of CH_x to produce CH₄ over the homogeneous dispersion of the CuCo catalyst, indicating that more CH_x intermediates were utilized to produce ethanol.