Photocatalytic degradation of sulphur-containing aromatic compounds in the presence of zeolite-bound 2,4,6-triphenylpyrylium and 2,4,6-triphenylthiapyrylium

A series of solid photocatalysts in which 2,4,6-triphenylpyrylium (TP+) or 2,4,6-triphenylthiapyrylium (TPTP+) are encapsulated within zeolites Y and Beta has been prepared and used for the photocatallytic degradation of thianthrene, diphenyl sulphide, diphenyl disulphide, benzothiophene and the cyclic propylene dithioacetal of acetophenone. TPTP+ was found more active than TP+ and the initial reaction rate is about one order of magnitude higher than that of P-25 TiO2 standard. The TPTP+ photocatalysts can be reused with moderate decay in their activity, but without noticeable self-degradation of the dye. The efficiency of the photocatalytic degradation depends considerably on the nature of the organosulphur compound, diphenyl disulphide and the cyclic dithioacetal being considerably easier degraded that dibenzothiophene that was the most difficult compound to decompose of the series. (C) 2004 Elsevier B.V. All rights reserved.