Performance of Mn-Ce co-doped siderite catalysts in the selective catalytic reduction of NOx by NH3
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摘要: 富含过渡元素的菱铁矿是用于制备选择性催化还原(SCR)脱硝催化剂的理想材料。在本研究中,对菱铁矿掺杂了Mn和Ce,并研究了Mn-Ce共掺杂改性菱铁矿在NH3-SCR反应中去除NOx的活性。结果表明,经过450℃煅烧后菱铁矿的主要成分FeCO3能够转化为Fe2O3。菱铁矿掺杂Mn和Ce后能够提高比表面积和表面酸度,降低硫酸铵盐在催化剂表面上的热稳定性。因此,Mn-Ce共掺杂改性菱铁矿催化剂表现出较高的SCR脱硝活性和抗硫性。3% Mn1% Ce-菱铁矿催化剂在脱硝效率高于90%的温度窗口能够拓宽至180-300℃,同时在引入SO2 7.5 h后该催化剂的脱硝效率仍高于75%。Abstract: Siderite, rich in the transition elements, is an idea material to prepare the catalysts for the selective catalytic reduction (SCR) of NOx by NH3. In this work, siderite was doped with Mn and Ce and the performance of Mn-Ce co-doped siderite catalysts in the removal of NOx (de-NOx) by SCR with NH3 was then investigated. The results illustrate that FeCO3 as the main component of siderite can be converted into Fe2O3 by calcination at 450℃. The doping of siderite with Mn and Ce can enhance the surface area and acidity of siderite and reduce the thermal stability of ammonium sulfate formed on the catalyst surface. As a result, the Mn-Ce co-doped siderite catalysts exhibit high efficiency in the de-NOx by SCR and high resistance against sulfur. Over the 3%Mn1%Ce-siderite catalyst, high NOx conversion (>90%) is achieved in the temperature window of 180-300℃; moreover, the NOx conversion remains above 75% even after introducing SO2 for 7.5 h.
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Key words:
- Mn-Ce co-doping /
- siderite /
- selective catalytic reduction /
- de-NOx /
- sulfur resistance
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Table 1 Textural properties of the siderite catalysts calcined at different temperatures
Calc. temperature t/℃ Surface area A/(m2·g-1) Pore volume v /(cm3·g-1) Pore size d/nm Uncalcined 21.5 0.025 4.7 400 42.8 0.055 4.8 450 64.8 0.138 9.7 500 58.4 0.133 9.1 Table 2 XRF analysis results of various Mn-modified siderite catalysts
Sample Composition w/% Fe Mn Si Al Mg Siderite 44.25 2.941 1.053 0.2834 0.4112 1%Mn-siderite 43.69 3.953 0.9820 0.2152 0.7329 2%Mn-siderite 42.94 5.074 0.9240 0.1978 0.6765 3%Mn-siderite 42.19 5.981 0.9060 0.1939 0.4534 Table 3 Textural properties of various Mn-modified siderite catalysts
Sample Surface area A/(m2·g-1) Pore volume v /(cm3·g-1) Pore size d /nm Siderite 64.8 0.138 9.7 1%Mn-siderite 68.4 0.133 8.7 2%Mn-siderite 71.0 0.146 8.2 3%Mn-siderite 73.2 0.137 7.5 Table 4 Experimental group setting for the investigation of the effect of Mn and Ce co-doping on the performance of modified siderite catalyst
Test number Mn doping amount /% Ce doping amount /% 1 0 0 2 3.0 0.5 3 3.0 1.0 4 3.0 1.5 5 1.0 1.0 6 2.0 1.0 -
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