The Influence of Active Biomolecules in Plant Extracts on the Performance of Au/TS‐1 Catalysts in Propylene Epoxidation

摘要

> An extract of Cinnamomum camphora ( CC ) leaves was adopted to prepare a Au/TS‐1 catalyst for vapor‐phase epoxidation of propylene. To explore the relationship between the active components in the extract and the performance of the resulting catalysts, the extract was roughly separated by silica gel column chromatography, and the separated samples were used to obtain a series of Au/TS‐1 catalysts. Carbohydrates, polyphenols, and flavonoids were found to be the main active components involved in the biosynthesis of Au catalysts. The catalyst prepared with flavonoids showed better performance than that prepared with polyphenols or carbohydrates. XPS spectra showed that the catalyst prepared with flavonoids was only loaded with Au 0 because flavonoids have the strongest reducing power among the three natural components. XRD and TEM results indicated no obvious size variation of Au NPs after calcination resulting from the presence of –COOH. In addition, the high surface hydrophobicity of the catalyst is helpful in improving its activity toward vapor‐phase epoxidation of propylene. The catalyst was not deactivated by the blocking of its active sites with carbonaceous deposits. The catalyst prepared with polyphenol and flavonoid components demonstrated remarkable stability, because the –COOH in these components tended to prevent Au NPs from agglomerating.