Competitive no, co and hydrocarbon oxidation reactions over a diesel oxidation catalyst

Abstract

The oxidation of NO, CO and hydrocarbons (HC) individually, in mixtures, and with NO2 were investigated over a monolith‐supported Pt/Al2O3 catalyst under oxidising conditions. Although competitive adsorption and inhibition by other species on oxidation reactions is a relatively well‐known phenomenon, this study represents a more comprehensive examination of such effects between key components in vehicle exhaust gases. NO2 was completely reduced by CO and C3H6, under NO2 limited conditions, at temperatures as low as 110°C and at temperatures above 140°C with dodecane and m‐xylene. NO2 was then again observed once the extent of oxidation of the other species by oxygen was significant. Under the conditions tested, NO, CO and HC oxidation was inhibited by NO2 in the feed gas mixture. HC were also found to inhibit the oxidation of NO and other HC species due to site adsorption competition. For CO, HC did not change the onset of oxidation, but did inhibit the extent after their light off began. At low temperatures, CO was initially found to inhibit NO oxidation, but at higher temperatures, once CO oxidation was significant, CO promoted NO conversion to NO2. The observed inhibition effects of the different gases on HC oxidation were not additive, indicating one species would cause inhibition, but once its inhibition ended, another species could still then cause inhibition. The combined effect of C3H6, NO and NO2 on CO conversion was found to be additive. This is because CO oxidation started prior C3H6. © 2011 Canadian Society for Chemical Engineering

Investigating carbon monoxide and propene oxidation on a platinum diesel oxidation catalyst

“…It might be possible to use this procedure with many more experiments for each species, but that would negate some of the value in this approach. Furthermore, recent work has shown the presence of complex intermediates on the surface, formed by the interactions of the two species, whose effects cannot be captured in single component experiments. The converse, using the parameters found from the experiments with combined feed to fit the experiments with feed containing only a single component, was also unsuccessful.…”

Low‐Temperature CO Oxidation over a Ternary Oxide Catalyst with High Resistance to Hydrocarbon Inhibition

“…The vast majority of commercial catalysts employed in automotive exhaust streams make use of supported platinum group metal (PGM) nanoparticles. There are a number of examples of PGM‐based catalysts showing exceptional activity for CO oxidation6–8 but upon introduction of hydrocarbons these catalysts experience severe inhibition due to competition for PGM active sites9 which limits their use for low temperature catalysis in practical applications. PGM catalysts are also susceptible to sintering at high temperature, which can also reduce crucial pollutant conversion at low temperature.…”

In Situ Investigations on the Facile Synthesis and Catalytic Performance of CeO2-Pt/Al2O3 Catalyst

“…Platinum-based catalysts have been widely used in the chemical industry for the catalytic dehydrogenation of light alkanes, such as ethane and propane [1,2], as well as the automotive industry to catalytically oxidize harmful pollutants, including CO, NO, and hydrocarbons [3][4][5][6]. Ceria has been used in automotive catalysts, due to its oxygen storage capacity and the ability to stabilize active metals [7][8][9].…”