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Ag-Cu based catalysts for the selective ammonia oxidation into nitrogen and water vapour.

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Title: Ag-Cu based catalysts for the selective ammonia oxidation into nitrogen and water vapour.
Authors: Jabłońska, Magdalena1,2 Jablonska@itmc.rwth-aachen.de, Beale, Andrew M.3,4, Nocuń, Marek5, Palkovits, Regina1,2 Palkovits@itmc.rwth-aachen.de
Source: Applied Catalysis B: Environment & Energy. Sep2018, Vol. 232, p275-287. 13p.
Subjects: Silver catalysts, Ammonia, Nitrogen, Water vapor, Catalytic activity
Abstract: XRD, BET, H 2 -TPR, UV–vis-DRS, XPS and XAFS were used to characterize a series of Ag and/or Cu – Ag (1–5%), Cu (10–15%) or Ag-Cu (1–1, 1–10, 1.5–10, 5–5% of metal) – supported on γ-Al 2 O 3 . Correlation between physicochemical properties, catalytic activity and selectivity in NH 3 -SCO were thoroughly investigated. Silver species mainly in the form of Ag 2 O on the Ag/Al 2 O 3 catalysts led to enhanced activity together with drop in N 2 selectivity with increasing silver loading up to 5%. A mixture of CuO and CuAl 2 O 4 formed on the Cu/Al 2 O 3 catalysts. Easily reducible highly dispersed CuO x promoted the activity of the catalysts, while bulk CuO x and CuAl 2 O 4 decreased N 2 selectivity up to 500 °C. The activity of all Cu-containing materials was inferior to Ag-containing ones. Thus, the gap between the high conversion temperature over Cu/Al 2 O 3 and low N 2 selectivity over Ag/Al 2 O 3 was bridged by applying the Ag-Cu/Al 2 O 3 catalysts, with the optimum loading of 1.5 and 10 wt.% for silver and copper, respectively. NH 3 -TPD, NH 3 -TPSR and in situ FTIR were used to determine the in situ selective catalytic reduction (i-SCR) mechanism over 1.5% Ag/Al 2 O 3 , 10% Cu/Al 2 O 3 and 1.5% Ag-10% Cu/Al 2 O 3 respectively. The i-SCR mechanism involved the partial oxidation of NH 3 into NO x species, along with adsorbed NO x species interacting with adsorbed ammonia (NH x species) and being reduced to reaction products. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:XRD, BET, H 2 -TPR, UV–vis-DRS, XPS and XAFS were used to characterize a series of Ag and/or Cu – Ag (1–5%), Cu (10–15%) or Ag-Cu (1–1, 1–10, 1.5–10, 5–5% of metal) – supported on γ-Al 2 O 3 . Correlation between physicochemical properties, catalytic activity and selectivity in NH 3 -SCO were thoroughly investigated. Silver species mainly in the form of Ag 2 O on the Ag/Al 2 O 3 catalysts led to enhanced activity together with drop in N 2 selectivity with increasing silver loading up to 5%. A mixture of CuO and CuAl 2 O 4 formed on the Cu/Al 2 O 3 catalysts. Easily reducible highly dispersed CuO x promoted the activity of the catalysts, while bulk CuO x and CuAl 2 O 4 decreased N 2 selectivity up to 500 °C. The activity of all Cu-containing materials was inferior to Ag-containing ones. Thus, the gap between the high conversion temperature over Cu/Al 2 O 3 and low N 2 selectivity over Ag/Al 2 O 3 was bridged by applying the Ag-Cu/Al 2 O 3 catalysts, with the optimum loading of 1.5 and 10 wt.% for silver and copper, respectively. NH 3 -TPD, NH 3 -TPSR and in situ FTIR were used to determine the in situ selective catalytic reduction (i-SCR) mechanism over 1.5% Ag/Al 2 O 3 , 10% Cu/Al 2 O 3 and 1.5% Ag-10% Cu/Al 2 O 3 respectively. The i-SCR mechanism involved the partial oxidation of NH 3 into NO x species, along with adsorbed NO x species interacting with adsorbed ammonia (NH x species) and being reduced to reaction products. [ABSTRACT FROM AUTHOR]
ISSN:09263373
DOI:10.1016/j.apcatb.2018.03.029