Cyril Thomas

Evidence for an H2 promoting effect in the selective catalytic reduction of NO(x) by propene on Au/Al2O3.

This work provides the first experimental evidence of an H2 effect in C3H6-SCR over an Au/Al2O3 catalyst. This effect could only be observed when the number of Au catalytic sites was decreased. The N2 turnover rate estimated for the first time for the Au catalytic sites for H2-C3H6-SCR was found to be similar to that estimated for Ag ones supported on Al2O3.

Promoting Ag/Al2O3 Performance in Low-Temperature H2-C3H6-SCR by Thermal Pretreatment of γ-Alumina in Water

AbstractThe present work highlights for the first time that a thermal treatment of γ-Al2O3 in water at 80u2009°C for 24xa0h prior to Ag deposition (Ag/Al2O3-OH) leads to a drastic enhancement of H2-C3H6-SCR performance at low temperature. This enhancement is attributed to the higher NOx coverage on Ag/Al2O3-OH compared with that of Ag/Al2O3. The higher NOx adsorption capacity of the sample prepared from the γ-Al2O3 thermally-treated in water is proposed to result from the preferential interaction of Ag with newly-created Al2O3 anchoring sites (Al(OH)3 bayerite domains), which were not available on the untreated pristine support.Graphical Abstractn

Selective Catalytic Reduction of NO x over Au/Al 2 O 3 : Influence of the Gold Loading on the Promoting Effect of H 2 in H 2 -Assisted C 3 H 6 -SCR of NO x

This article reports on the promotional effect of adding H2 to the reaction feed for the selective catalytic reduction of NOx with propene (H2–C3H6-SCR) over Au/Al2O3 catalysts. For this purpose, the influence of the Au loading in H2–C3H6-SCR was investigated. The H2 promoting effect in C3H6-SCR, well-established for Ag/Al2O3, was also demonstrated for Au/Al2O3. Although less pronounced than for Ag-based systems, the H2 effect allowed for a substantial increase in NOx conversion at temperatures higher than 250xa0°C on Au/Al2O3 samples. The highest NOx to N2 conversion in H2–C3H6-SCR was obtained for lowly-loaded gold samples (~u20091xa0wt% Au) with the smallest gold particle sizes. An increase in H2 concentration in the reaction feed also led to an increase in NOx conversion. The experiments performed in the present study as a function of the reaction temperature underlined the fact that concomitant activation of H2 and C3H6 is critical to achieve a high H2 promoting effect in H2–C3H6-SCR. Whereas this requirement is fulfilled for Ag/Al2O3, a temperature gap between the oxidation profiles of H2 and C3H6 remains for Au/Al2O3 due to the early oxidation of H2 on gold nanoparticles, which therefore limits the NOx conversion at low temperature.Graphical Abstract