Polyoxometalate-Modified Fabrics: New Catalytic Materials for Low-Temperature Aerobic Oxidation

The polyoxometalate H5PV2Mo10O40 (1) is deposited on cotton cloth, polyacrylic fiber, nylon fiber, carbon powder (Ambersorb 572), and the Japanese “self-deodorizing” fabric Smoklin by immersion of these materials in aqueous solutions of 1 followed by evaporation of the water. DRIFT spectra and chemical reactivity indicate that 1 is not damaged during deposition on the materials. More significantly, they catalyze O2-based oxidations of two representative and common toxics in air, acetaldehyde and 1-propanethiol, in addition to a representative thioether, tetrahydrothiophene. These aerobic oxidations proceed heterogeneously with the substrates in the liquid phase and under unusually mild conditions (mostly ambient temperature and pressure). One representative reaction, CH3CHO+O2→CH3COOH, catalyzed by several 1–fabric materials is examined in some detail. Kinetics, radical scavenging, and other experiments are consistent with the 1–fabric functioning primarily as a radical chain initiator. Surface area measurements and scanning electron microscopy of two representative materials, 1–polyacrylic and 1–Smoklin, before and after deposition of 1 and after catalysis indicate that the fibers are not demonstrably altered by deposition of 1, and that the 1–fabric catalysts are not significantly deactivated by use. In all cases, the surface areas are <0.5 m2/g by BET N2 adsorption, and the deposition morphology is clumps of 1 microcrystals covering <5% of the fiber/cloth surface. Smoklin, designed and specified to be effective at removing the toxic and/or odorous molecules at ambient temperature, does not exhibit significant activity for catalytic O2 oxidations in our evaluations. In contrast, 1–Smoklin is quite acti ve for all these processes.