*3.1. Materials*

The industrial catalyst TS-1 (SiO2/TiO2 = 56, specific surface area of 394.7 m<sup>2</sup>/g) was provided by Luxi Chemical Group Co., Ltd. Analytical grade ammonia (25%, AR, Laiyang, Shandong, China), hydrogen peroxide (30%, AR, Laiyang, Shandong, China), t-butanol (≥99%, AR, Shanghai, China), MEK (≥99%, AR, local vendor), nickel nitrate hexahydrate (98%, AR, Shanghai, China), Cobalt nitrate hexahydrate (98%, AR, Shanghai, China), Ferric nitrate nine-hydrate (≥99%, AR, Tianjin, China), Copper nitrate trihydrate (≥99%, AR, Tianjin, China), Cerium nitrate hexahydrate (98%, AR, Shanghai, China), and Anhydrous sodium carbonate (≥99.8%, AR, Xuzhou NO.2 Reagent Factory) were all obtained commercially.
