INVESTIGATION OF THE EFFECT OF WATER, ACIDS, AND BASES IN THE GAS-STREAM IN THE CATALYTIC FORMATION OF PCDD AND PCDF OVER MSW FLY-ASH

Municipal solid waste (MSW) incinerator fly ash has previously been implicated in the formation of PCDD and PCDF during MSW incineration. This paper describes a series of experiments conducted to further investigate the role of the fly ash using carrier gas components that may inhibit or enhance PCDD/F formation. Model compounds were used to probe the formation of dioxins and furans. The role of water in the gas stream was investigated and it was found that at the typical moisture levels found in incinerators (approximately 15%) water in the gas stream can enhance the catalytic activity of fly ash. Ammonium hydroxide permanently inhibits the formation of PCDD from pentachlorophenol over MSW fly ash but does not inhibit the formation of PCDF from pentachlorodiphenylether. It was also found that some acidic components could not only enhance the catalytic activity of fly ash but also regenerate catalytic sites in fly ash which had lost its activity. © 1990.