Carbon Powder and Fiber-Supported Polyoxometalate Catalytic Materials. Preparation, Characterization, and Catalytic Oxidation of Dialkyl Sulfides as Mustard (HD) Analogues

摘要

We report here a prototype material for the sustained catalytic decontamination of mustard analogues with the ultimate goal being the fabrication of self-decontaminating clothing. H_5PV_2Mo_(10)O_(40) (1) can be supported on carbon cloths as well as powders, with 1/Ambersorb 572 being the best material (high catalytic activity and low desorption of 1). Evaluation of the desorption of 1 from six carbon supports indicates that the PPAN (pyrolyzed polyacry-lonitrile) and Ambersorb 572 materials are highly effective at retaining the immobilized 1 even under catalytic conditions (oxidation of tetrahydrothiophene, THT, by tert-butyl hydroperoxide, TBHP). The products of THT oxidation, tetrahydrothiophene oxide (THTO) and tert-butyl alcohol (TBA), inhibit the reaction at high conversions; however, the catalytic activity can be restored by heating in a vacuum oven to 80℃. The reactivity for oxidation of four different thioethers by TBHP catalyzed by 1 supported on hydrophobic (Ambersorb 563) and hydrophilic (Ambersorb 572) carbon powders indicates that while the steric and electronic characteristics of the thioether substrates are a factor in reactivity, the hydrophobicity of the carbon support is not.