A Heterogeneous Phosphomolybdate Nanocatalyst Utilizes Vitamin B1 to Promote Solvent-Free H2O2 Sulfoxidation Selectivity

چکیده مقاله

Catalyst design and fabrication with safe and affordable components and methods is a high-value-added business. In this work, a vitamin-based hybrid nanomaterial (PMoB1) is prepared by simple stirring of thiamine hydrochloride (vitamin B1, VB1) as an inexpensive commercially available biologically active compound with phosphomolybdic acid (PMo12) in acidic aqueous solution to catalyze selective oxidation of sulfides using aqueous H2O2. A small amount of this heterogeneous catalyst drives rapidly the sulfoxidation reaction under mild and solvent-free conditions facilitating the product separation and reducing significantly the environmental impacts. The main factors of the catalytic reaction were optimized by the central composite design (CCD) method. The solid catalyst tolerates a wide range of pH and retained its structural integrity even at alkaline solution (pH=11). PMoB1 composed of two VB1 and one PMo12 was found to be partially reduced based on 13P NMR and UV–Vis spectra. An amorphous structure with aggregated nanoparticles with sizes ranging between 50 and 70nm and a specific surface area of 35m2/g are important reasons for enhanced catalytic activity and selectivity. Nevertheless, non-covalent interactions such as hydrogen bonding and the π–π stacking can also significantly affect the catalyst performance. Given the scavenging tests and spectral evidences, a non-radical mechanism involving peroxo species is postulated. The catalysis is shown to be truly heterogeneous while the solid catalyst largely maintains its structural integrity during the recycling test.