Novel Gallium Polyoxometalate/Nano‐Gold Hybrid Material Supported on Nano‐sized Silica for Mild Cyclohexene Oxidation Using Molecular Oxygen

• Published in: Bulletin of the Korean Chemical Society 2017, 38(6), , pp.614-624
• Main Authors: Jameel, Umsa, Zhu, Mingqiao, Chen, Xinzhi, Chen, Hengquan, Iqbal, Nousheen, Tong, Zhangfa, Timayo, Satmon John
• Format: Article
• Language: English
• Subjects: Cyclohexene oxidation; Gold nanoparticles; Hybrid materials; Nano‐sized silica; Polyoxometalates; 화학
• ISSN: 1229-5949; 0253-2964; 1229-5949
• DOI: 10.1002/bkcs.11135

Selective oxidation of olefins using molecular oxygen is a great challenge. This study reports two types of novel eco‐friendly heterogeneous hybrid catalysts. One comprises of a lacunary Keggin‐type polyoxometalate (POM) GaW11 linked to nano‐sized silica using (3‐aminopropyl) triethoxysilane (APTES) to form GaW11‐APTES@SiO2 . Another catalyst is Au/GaW11‐APTES@SiO2 prepared by wet deposition of nano‐gold on the former one. The catalysts were characterized and used for the solvent‐free oxidation of cyclohexene with molecular oxygen under mild reaction conditions. Both the catalysts showed good conversion and significant selectivity towards oxidized products for cyclohexene. GaW11‐APTES@SiO2 showed a high conversion of up to 62.02% with a selectivity of 59.13% towards epoxide at a mild temperature of 50°C. Au/GaW11‐APTES@SiO2 showed a conversion of 69.32% with 57.34% selectivity to 2‐cyclohexene‐1‐ol at a temperature of 80°C. The heterogeneous catalysts were reused several times with no significant loss in conversion or selectivity towards the oxidized products.