Surface catalysed PCDD/F formation from precursors - high PCDF yield does not indicate de novo mechanism!. (2017)

• Record Type: Journal Article
• Authors: Nganai, Shadrack; Lomnicki, Slawo
• Is Part Of: International journal of environment and pollution. Volume 61:Number 3/4(2017)
• Page Start: 208
• Page End: 222
• Publication Date: 2017
• Subjects: PCDD&amp -- #47 -- Fs -- iron (III) oxide -- precursor pathway -- de novo -- dioxin formation; Environmental policy -- Periodicals; Environmental engineering -- Periodicals; Environmental sciences -- Periodicals; Pollution -- Periodicals; 363.73
• Languages: English
• ISSNs: 0957-4352

Abstract

We report results on PCDD/F formation over iron (III) oxides catalysts for a mixture of 2-monochlorophenol (2-MCP) and 1, 2-dichlorobenzene (1, 2-DCBz) for both oxidation and pyrolysis. Competitive adsorption between chlorinated benzenes and chlorinated phenols affects the transformation of these precursors and plays a crucial role in the PCDD/F formation in mixed MCP/1, 2-DCBz-feed streams. Comparing the integrated PCDD and PCDF yields, it becomes apparent that with decreasing 2-MCP content in the feed stream the PCDF yield first rises and then levels off, at ~0.4% for pyrolytic and at ~0.6% for oxidative conditions. Present results further confirm that the PCDD/PCDF-ratio cannot be used to validate the de novo pathway nor can it be used as an indicator of de novo synthesis in incinerators. In fact, the PCDD/PCDF-ratio is strongly dependent on the relative concentration of these two precursors in the reacting stream, i.e., chlorinated benzenes vs. chlorinated phenols.