Carbon nanotube-supported metal catalysts for NOx reduction using hydrocarbon reductants: Gas switching and adsorption studies

Eduardo Santillan-Jimenez, Mark Crocker, Agustín Bueno-López, Concepción Salinas-Martínez De Lecea

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

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.

Original languageEnglish
Pages (from-to)7191-7200
Number of pages10
JournalIndustrial and Engineering Chemistry Research
Volume50
Issue number12
DOIs
StatePublished - Jun 15 2011

ASJC Scopus subject areas

  • General Chemistry
  • General Chemical Engineering
  • Industrial and Manufacturing Engineering

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