Nanoporous montmorillonite clay stabilized copper nanoparticles: Efficient and reusable catalyst for oxidation of alcohols

Stable and spherical copper nanoparticles of size less than 10 nm were generated into nanopores of activated montmorillonite clay and evaluated their catalytic activity for liquid phase alcohol oxidation to corresponding carbonyl compounds. Synthesis of copper nanoparticles was accomplished by incipient wetness impregnation of Cu(CH3COO)(2) into the nanopores of the acid activated montmorillonite followed by reduction with NaBH4. The activation of montmorillonite was carried out by treating with mineral acid such as H2SO4 under controlled conditions at 80 degrees C to generate nanopores and high surface area. Powder-XRD, SEM-EDX, HRTEM, N-2 adsorption, XPS etc. analysis were carried out to characterize the stabilized copper nanoparticles as well as the support. The synthesized copper nanoparticles may serve as a new alternative to ligand and additive free green catalyst for broad range of oxidation of alcohols with molecular O-2 to corresponding carbonyl compounds with excellent yields (up to 97%) and selectivity (100%) under mild reaction conditions. The metal nanocatalysts exhibit good reusability, simple workup procedure and straightforward approach to carbonyl compound formation. (C) 2017 Elsevier B.V. All rights reserved.