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Ag-Cu based catalysts for the selective ammonia oxidation into nitrogen and water vapour
Applied Catalysis B: Environment and Energy ( IF 22.1 ) Pub Date : 2018-03-11
Magdalena Jabłońska, Andrew M. Beale, Marek Nocuń, Regina Palkovits

XRD, BET, H2-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-Al2O3. Correlation between physicochemical properties, catalytic activity and selectivity in NH3-SCO were thoroughly investigated. Silver species mainly in the form of Ag2O on the Ag/Al2O3 catalysts led to enhanced activity together with drop in N2 selectivity with increasing silver loading up to 5%. A mixture of CuO and CuAl2O4 formed on the Cu/Al2O3 catalysts. Easily reducible highly dispersed CuOx promoted the activity of the catalysts, while bulk CuOx and CuAl2O4 decreased N2 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/Al2O3 and low N2 selectivity over Ag/Al2O3 was bridged by applying the Ag-Cu/Al2O3 catalysts, with the optimum loading of 1.5 and 10 wt.% for silver and copper, respectively. NH3-TPD, NH3-TPSR and in situ FTIR were used to determine the in situ selective catalytic reduction (i-SCR) mechanism over 1.5% Ag/Al2O3, 10% Cu/Al2O3 and 1.5% Ag-10% Cu/Al2O3 respectively. The i-SCR mechanism involved the partial oxidation of NH3 into NOx species, along with adsorbed NOx species interacting with adsorbed ammonia (NHx species) and being reduced to reaction products.



中文翻译:

Ag-Cu基催化剂,用于将氨选择性氧化为氮气和水蒸气

XRD,BET,H 2 -TPR,UV-vis-DRS,XPS和XAFS用于表征一系列的Ag和/或Cu – Ag(1-5%),Cu(10-15%)或Ag-Cu (1-1,1-10,1.5-10,5-5金属的%) -负载在γ-Al系2 ö 3。深入研究了在NH 3 -SCO中的理化性质,催化活性和选择性之间的关系。在Ag / Al 2 O 3催化剂上主要以Ag 2 O形式存在的银物种导致活性增强,同时N 2选择性下降,从而使银载量增加至5%。在Cu / Al 2 O 3上形成的CuO和CuAl 2 O 4的混合物催化剂。易还原的高分散CuO x促进了催化剂的活性,而块状CuO x和CuAl 2 O 4降低了N 2的选择性,直至500°C。所有含铜材料的活性均低于含银材料。因此,高转化温度之间在铜/铝的间隙2 ö 3和低氮2选择性的Ag / Al的2 ö 3通过应用Ag-Cu系/ Al的桥接2种ö 3种催化剂,具有1.5的最佳装载和银和铜分别为10重量%。NH 3 -TPD,NH 3-TPSR和原位FTIR被用来确定在原位选择性催化还原(I-SCR)超过1.5%的Ag / Al的机构2 ö 3,10%铜/铝2 ö 3和1.5%的Ag-10%铜/铝2 O 3分别。i-SCR机理包括将NH 3部分氧化为NO x物种,以及与吸附的氨(NH x物种)相互作用的被吸附的NO x物种,并被还原为反应产物。

更新日期:2018-03-12
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