Highly reducible CuO species were created by the calcination of a Cu-Al layered double hydroxide (CuAl LDH) at 1073 K under air. After this heat treatment, the original layered double hydroxide structure was completely transformed into CuO and CuAl2O4 phases. The synthesized calcined CuAl LDH (calc-CuAl LDH) promoted the catalytic hydrogenation of furfural (FALD) into furfuryl alcohol (FOL) with formic acid (FA) as a hydrogen donor. In the initial stage of the above catalytic reaction, the CuO species in the calc-CuAl LDH matrix transformed into active Cu0 species via the formation of a Cu(HCOO)2-1,4-dioxane complex in the liquid phase. The spent catalyst was also reusable without loss of its high catalytic performance.

A CuO-CuAl2O4 nanocomposite (CuAl NC) synthesized by high temperature calcination of Cu-Al layered double hydroxides (CuAl LDHs) acted as an effective heterogeneous catalyst for acceptorless dehydrogenation of various alcohols. The catalytically active Cu0 species was formed by in situ reduction with alcohol. The catalytic activity strongly depended on the Cu/Al ratio in preparation and calcination temperature. The synthesized catalyst was reusable without loss of its high activity and selectivity.

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A silica-supported copper (Cu/SiO2) catalyst containing highly dispersed Cu nanoparticles was prepared via a crown-ether-assisted impregnation method. A 12-crown-4-ether-assisted Cu/SiO2 catalyst outperformed several Cu/SiO2 catalysts prepared with various organic additives in the dehydrogenation of 2,3- and 1,4-butanediol. It was found that the catalytic activity, i.e., the formation rate of acetoin from 2,3-butanediol and that of γ-butyrolactone from 1,4-butanediol, was proportional to the copper surface area.

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