TY - JOUR
T1 - Carbon nanotube-supported metal catalysts for NOx reduction using hydrocarbon reductants
T2 - Gas switching and adsorption studies
AU - Santillan-Jimenez, Eduardo
AU - Crocker, Mark
AU - Bueno-López, Agustín
AU - Salinas-Martínez De Lecea, Concepción
PY - 2011/6/15
Y1 - 2011/6/15
N2 - The selective catalytic reduction of NOx with hydrocarbons (HC-SCR) on functionalized multiwalled carbon nanotube (fMWCNT)-supported metal catalysts was investigated using a transient technique, together with kinetic and adsorption measurements. Results from the transient studies provide an explanation for the characteristic volcano shape of the NOx conversion curves: below Tmax, the temperature of maximum NO x conversion, the catalyst surface is covered by hydrocarbonaceous species, which results in the suppression of NOx reduction activity. Above Tmax, O2 adsorption becomes prevalent, favoring oxidation of both NO and the hydrocarbon. In an effort to understand the origin of the superior NOx reduction activity shown by 3:1 Pt-Rh/fMWCNTs as compared to Pt/fMWCNTs, Temperature Programmed Desorption (TPD) measurements were undertaken. Results indicate that hydrocarbon and/or hydrocarbon-derived species are more strongly adsorbed on the alloy than on Pt alone, while NO adsorption is weaker on the alloy than on Pt. This is suggested to give rise to a higher concentration of partially oxidized hydrocarbon intermediates on the surface of the Pt-Rh catalyst at the temperature of maximum deNOx activity, leading to higher NOx reduction activity.
AB - The selective catalytic reduction of NOx with hydrocarbons (HC-SCR) on functionalized multiwalled carbon nanotube (fMWCNT)-supported metal catalysts was investigated using a transient technique, together with kinetic and adsorption measurements. Results from the transient studies provide an explanation for the characteristic volcano shape of the NOx conversion curves: below Tmax, the temperature of maximum NO x conversion, the catalyst surface is covered by hydrocarbonaceous species, which results in the suppression of NOx reduction activity. Above Tmax, O2 adsorption becomes prevalent, favoring oxidation of both NO and the hydrocarbon. In an effort to understand the origin of the superior NOx reduction activity shown by 3:1 Pt-Rh/fMWCNTs as compared to Pt/fMWCNTs, Temperature Programmed Desorption (TPD) measurements were undertaken. Results indicate that hydrocarbon and/or hydrocarbon-derived species are more strongly adsorbed on the alloy than on Pt alone, while NO adsorption is weaker on the alloy than on Pt. This is suggested to give rise to a higher concentration of partially oxidized hydrocarbon intermediates on the surface of the Pt-Rh catalyst at the temperature of maximum deNOx activity, leading to higher NOx reduction activity.
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U2 - 10.1021/ie200054u
DO - 10.1021/ie200054u
M3 - Article
AN - SCOPUS:79958826972
SN - 0888-5885
VL - 50
SP - 7191
EP - 7200
JO - Industrial and Engineering Chemistry Research
JF - Industrial and Engineering Chemistry Research
IS - 12
ER -