Catalytic wet hydrogen peroxide oxidation of isoeugenol to vanillin using microwave-assisted synthesized metal loaded catalysts

Abstract

• Supported metal nanoparticles (Cu, W, Mo) on a silica matrix using a one-pot microwave-assisted protocol. • Catalytic activity evaluated in the oxidation of isoeugenol into vanillin. • Moderate conversions, up to 50–60 % (for Cu-MINT). • Acceptable selectivities towards vanillin production (22–45 %). • High catalyst stability (imperceptible decrease of activity after the fourth use). Supported metal nanoparticles (Cu, W, Mo among others) have been stabilized on a silica matrix following an efficient and sustainable one-pot microwave-assisted protocol. The materials synthesized were characterized, mainly, by nitrogen adsorption desorption measurements, X-ray diffraction (XRD), scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDS). The materials exhibited large surface area and pore size in the mesopore range. The incorporation of metal particles in the silica matrix was also confirmed with particle size in a wide range between 2 and 52 nm. The catalytic activity of the resulting materials was evaluated in the catalytic wet oxidation of isoeugenol into vanillin using hydrogen peroxide as oxidant. The catalysts shown moderate conversions, up to 50–60 % for Cu-MINT with acceptable selectivity towards vanillin production (22–45 %), obtaining dimers as main side products. The stability of the catalysts was investigated as well, obtaining an imperceptible decrease after the fourth use.