Formation of Environmentally Persistent Free Radicals on α-Al2O3

Document Type

Article

Publication Date

10-18-2016

Abstract

Metal oxides exhibit catalytic activity for the formation of environmentally persistent free radicals (EPFRs). Here, we investigate, via first-principles calculations, the activity of alumina α-Al2O3(0001) surface toward formation of phenolic EPFRs, under conditions relevant to cooling down zones of combustion systems. We show that, molecular adsorption of phenol on α-Al2O3(0001) entails binding energies in the range of -202 kJ/mol to -127 kJ/mol. The dehydroxylated alumina catalyzes the conversion of phenol into its phenolate moiety with a modest activation energy of 48 kJ/mol. Kinetic rate parameters, established over the temperature range of 300 to 1000 K, confirm the formation of the phenolate as the preferred pathways for the adsorption of phenol on alumina surfaces, corroborating the role of particulate matter in the cooling down zone of combustion systems in the generation of EFPRs.

Publication Source (Journal or Book title)

Environmental Science and Technology

First Page

11094

Last Page

11102

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