Characterization and deNO x activity of copper-hydroxyapatite catalysts prepared by wet impregnation

International audienceCopper loaded hydroxyapatite catalysts have been prepared by wet impregnation and have been tested in the selective catalytic reduction of NO by NH3. The catalyst characterization showed the presence of copper oxide nanoparticles entrapped in the mesoporous matrix thus obstructing the Ca-Hap channel apertures. With increasing copper loading, there is a deposition of copper oxide clusters, on the surface of the carrier, containing Cu2+ and Cu+ ions. Compared to the catalyst prepared by the ion exchange method, Cu(1.12)Hapi.e, which exhibited excellent NO conversion over a broad temperature range, the impregnated catalysts are less efficient in the selective catalytic reduction of NO by NH3

Selective Catalytic Reduction of Nitrogen Oxide by Ammonia over Copper-Hydroxyapatite Catalysts Prepared in Organic Medium

International audienceCopper loaded hydroxyapatite catalysts have been prepared in organic medium by reaction/evaporation and impregnation methods and have been tested in the selective catalytic reduction of NO by NH3. The catalyst characterizations showed the presence of CuO and Cu2O particles deposited on the surface of the carrier in different environments and sizes. Compared to the catalysts prepared by ion exchange and impregnation in aqueous medium method, the ones prepared in organic medium are less efficient in the selective catalytic reduction of NO by NH3

Selective catalytic reduction of NO by NH3 over copper-hydroxyapatite catalysts: effect of the increase of the specific surface area of the support

International audienceThe influence of the increase of the specific surface area of the support Ca-HAp on the dispersion of copper species and their activity in the NO-SCR by NH3 has been studied. The copper ion exchange does not alter the Ca-HAp structure whatever the copper concentration. The increase of the specific surface area of the support changed the dispersion and the reducibility of copper species. The high NO conversion in the whole temperature range for the catalyst with the lowest specific surface area (35 m2/g) was related to the highly dispersed CuO particles that are easily reduced. Nevertheless, the increase of the specific surface area of the support (76 m2/g), induces an increase of the size of CuO particles that become less active in NO-SCR by NH3. The addition of 2.5 % of H2O to the reaction gas feed strongly affects the NO conversion in the whole temperature range. This deactivation can be related to the change of the nature of copper species rather than to the destruction of the Ca-HAp structure

NO reduction with NH3 under oxidizing atmosphere on copper loaded hydroxyapatite

International audienceCopper loaded hydroxyapatite catalysts were prepared by ion exchange in aqueous phase. The copper ion exchange capacity of hydroxyapatite host structure is highly dependent on the initial copper concentration of the solution. For the lowest concentration, a pH variation of the exchange solution is observed. This change in pH may allow the deposition of a small amount of copper hydroxide at the expense of cationic substitution of copper. The increase in copper content exchanged has no effect on the profile of conversion of NO by NH3. From this, it is assumed that the copper cations substituted for calcium are not active in the reaction. The profiles of NO conversion obtained, are in agreement with the presence of a small amount of copper oxide clusters deposited on the surfaces of the apatite