Formation of Environmentally Persistent Free Radicals on α-Al2O3.
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.
School of Engineering and Information Technology, Murdoch University , 90 South Street, Murdoch, Western Australia 6150, Australia.
Niveen W
NW
Assaf
School of Engineering and Information Technology, Murdoch University , 90 South Street, Murdoch, Western Australia 6150, Australia.
Mohammednoor
M
Altarawneh
School of Engineering and Information Technology, Murdoch University , 90 South Street, Murdoch, Western Australia 6150, Australia.
Ibukun
I
Oluwoye
School of Mathematical and Physical Sciences, The University of Newcastle , Callaghan, NSW 2308, Australia.
Marian
M
Radny
Department of Environmental Sciences, Louisiana State University , Baton Rouge, Louisiana 70803, United States.
Slawomir M
SM
Lomnicki
School of Engineering and Information Technology, Murdoch University , 90 South Street, Murdoch, Western Australia 6150, Australia.
Bogdan Z
BZ
Dlugogorski