Nitrogen oxides (NOx) are known to have a harmful impact on the environment and human health. Selective Catalytic Reduction by ammonia (NH3-SCR) is one among the most performant technologies for NOx abatement1. In view of ever more stringent regulations for the NOx emissions, the development of more active and selective catalysts with ecofriendly properties represents an unavoidable challenge. Stoichiometric calcium hydroxyapatite (Ca10(PO4)6(OH)2, HAP) is an inorganic material, bioavailable, of low cost, easily modulable for the number of acid-base sites, and capable to exchange the calcium atoms with some other metal ions of catalytic interest and allocate them into its lattice (Me/HAP). Herein, we present our recent studies aimed to show the potentiality of metal functionalized HAP samples as novel catalysts for NH3-SCR reaction1-3. We have studied the introduction of Cu(II) o Fe(III) in different amount (metal loading: 1.5 < wt.% < 12) onto a synthetic HAP framework, starting from different precursors (copper acetate or copper nitrate and iron nitrate) and preparative methods (e.g. ion exchange, wet impregnation). The catalytic performances of the functionalized hydroxyapatite materials have been evaluated in NH3-SCR tests carried out in the 120-500°C interval with different NH3/NO ratios and at fixed contact time. XRPD, Uv-vis-DRS, EPR, and Mössbauer analyses provided fundamental details on the catalyst properties, metal (Cu or Fe) sitting and speciation on HAP surface. As a general trend, Cu/HAP samples resulted more active than Fe-based ones, which worked at higher temperature (Figure). The better performances have been observed on catalysts loaded with ca. 6 wt.% of Cu and Fe, independently on the method of metal deposition used. The observed behaviour indicated that SCR activity and selectivity to N2 are very sensitive to the dimension of the formed metal species. Further investigations are in progress to optimize the catalysts for an applicative purpose.
Copper and iron functionalized hydroxyapatite as eco-friendly catalysts for NH3-SCR reaction / M.G. Galloni, S. Campisi, A. Gervasini. ((Intervento presentato al convegno ELITECAT : Summer School in Catalysis tenutosi a Villeurbanne, Lyon nel 2019.
Copper and iron functionalized hydroxyapatite as eco-friendly catalysts for NH3-SCR reaction
M.G. Galloni
;S. Campisi;A. Gervasini
2019
Abstract
Nitrogen oxides (NOx) are known to have a harmful impact on the environment and human health. Selective Catalytic Reduction by ammonia (NH3-SCR) is one among the most performant technologies for NOx abatement1. In view of ever more stringent regulations for the NOx emissions, the development of more active and selective catalysts with ecofriendly properties represents an unavoidable challenge. Stoichiometric calcium hydroxyapatite (Ca10(PO4)6(OH)2, HAP) is an inorganic material, bioavailable, of low cost, easily modulable for the number of acid-base sites, and capable to exchange the calcium atoms with some other metal ions of catalytic interest and allocate them into its lattice (Me/HAP). Herein, we present our recent studies aimed to show the potentiality of metal functionalized HAP samples as novel catalysts for NH3-SCR reaction1-3. We have studied the introduction of Cu(II) o Fe(III) in different amount (metal loading: 1.5 < wt.% < 12) onto a synthetic HAP framework, starting from different precursors (copper acetate or copper nitrate and iron nitrate) and preparative methods (e.g. ion exchange, wet impregnation). The catalytic performances of the functionalized hydroxyapatite materials have been evaluated in NH3-SCR tests carried out in the 120-500°C interval with different NH3/NO ratios and at fixed contact time. XRPD, Uv-vis-DRS, EPR, and Mössbauer analyses provided fundamental details on the catalyst properties, metal (Cu or Fe) sitting and speciation on HAP surface. As a general trend, Cu/HAP samples resulted more active than Fe-based ones, which worked at higher temperature (Figure). The better performances have been observed on catalysts loaded with ca. 6 wt.% of Cu and Fe, independently on the method of metal deposition used. The observed behaviour indicated that SCR activity and selectivity to N2 are very sensitive to the dimension of the formed metal species. Further investigations are in progress to optimize the catalysts for an applicative purpose.File | Dimensione | Formato | |
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