Cloth catalysts in water denitrification - I. Pd on glass fibers

Fiber catalysts are easy to handle and free of mass-transfer resistance. Th is report is the first application of cloth catalysts to water denitrificat ion. In this work, cloths woven from glass fibers (GF) of 7-10 mu m in diam eter, impregnated with Pd, were tested in a semi-batch reactor to evaluate their effectiveness in the catalytic liquid phase hydrogenation of nitrites and nitrates. The catalytic properties of Pd-GF cloths were evaluated as a function of Pd loading as well of chemical composition of the glass, specific surface are a and weaving mode of the fibrous support. Investigated catalysts showed th e same level of specific activity (per g Pd) as conventional powdered catal ysts for liquid-phase hydrogenation of nitrites but their activity for nitr ates was about one order of magnitude lower. The nitrite and nitrate remova l activities were independent of the catalyst structure; the formation of a mmonium ions was highly sensitive to reactant concentration. The stability of Pd-GF cloths is discussed. (C) 2000 Elsevier Science B.V. All rights res erved.