• propene epoxidation with oxygen over gold clusters: role of basic salts and hydroxides of alkalis

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    • تاریخ ارائه: 1392/07/24
    • تاریخ انتشار در تی پی بین: 1392/07/24
    • تعداد بازدید: 958
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     titanosilicalite-1 (ts-1) was first treated with aqueous koh solution to introduce surface defects. then koh-treated ts-1 (ts-1k) was further treated with aqueous hno3 solution to remove residual potassium. then, au was deposited by solid grinding on this support free of k (ts-1kh) as 1.6 nm clusters, which could be stabilized by surface detects. finally, au/ts-1kh was modified by impregnating potassium salts, alkali hydroxides or alkaline earth metal acetates. xrd and uv–vis spectra indicated that the crystalline mfi structure and 4-fold coordinated ti4+ sites of ts-1 were maintained even after different treatments. haadf-stem showed that after the modification of au/ts-1-kh the mean diameter of au clusters increased only slightly from 1.6 nm to 1.8 nm. in propene epoxidation with molecular o2 and h2o, au/ts-1kh promoted by basic potassium salts (ch3coo, co32− and po43−) or hydroxides of na, k, rb and cs could produce po with the selectivity of 12–45%, while au/ts-1kh combined with neutral potassium salts (kcl, kno3 and k2so4), lioh or alkaline earth metal acetates could not produce po.

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