MnFeTiO x /attapulgite catalysts with excellent potassium resistance for SCR of NO x with NH 3 at low temperatures
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MnFeTiOx/attapulgite catalysts with excellent potassium resistance for SCR of NOx with NH3 at low temperatures Yiran Tang1,c), Yiyang Tao2,c), Jiayi Wu1, Linjing Xu1, Xiaoyan Huang1, Xingmeng Zhou1, Aijuan Xie1,a), Shiping Luo1,b), Chao Yao1, Xiazhang Li1 1
School of Petrochemical Engineering, Changzhou University, Changzhou 213164, People’s Republic of China School of Fine Arts, Nanjing Normal University, Nanjing 210046, People’s Republic of China a) Address all correspondence to these authors. e-mail: [email protected] b) e-mail: [email protected] c) These authors contributed equally to this work. 2
Received: 17 November 2018; accepted: 16 January 2019
A series of metal oxides (MnFeOx, MnCrOx, MnTiOx, and MnFeTiOx) supported on attapulgite (ATP) were synthesized by coprecipitation for the low-temperature selective catalytic reduction (SCR) of NOx with NH3. Then, they were subjected to appropriate characterizations for their properties (XRD, TEM, BET, XPS, etc.). The catalytic activity of MnFeTiOx/ATP catalyst was over 95% NOx conversion within a wide temperature window between of 175 and 300 °C, and 88% N2 selectivity. Moreover, MnFeTiOx/ATP presented excellent potassium resistance relative to the traditional V–W–Ti catalyst, and its denitration performance was significantly improved. The NOx conversion rate could be restored to nearly 90% at 210 °C after removing potassium via washing of K–MnFeTiOx/ATP. In addition, the MnFeTiOx/ATP showed better SO2 resistance and stability than the traditional V–W–Ti catalyst. Therefore, the MnFeTiOx/ATP catalyst has been proved to have broad prospects in NH3-SCR.
Introduction Nitrogen oxides (NOx) are common and extremely harmful atmospheric pollutants, including NO, NO2, N2O, N2O3, and N2O4, in which the contribution of NO and NO2 accounts for more than 90% of the total amount of NOx [1, 2, 3, 4]. As an air pollutant, NOx cause serious harm not only to human health and safety, but also to the ecosystem. NO2 in the air easily combines with water vapor to form liquid nitric acid and then falls to the ground in the form of rainwater, thus causing a series of problems such as acidification of water, death of vegetation, corrosion of buildings, and aging of rubber products [5, 6, 7]. In recent years, the selective catalytic reduction (SCR) of NOx by NH3 (NH3-SCR) has been considered the most efficient technique to remove NOx from coal-fired flue gas [8]. The main principle of NH3-SCR of NOx is to use NH3 or CO(NH2)2 as a reductant to react selectively with NO under the action of catalyst. The conversion of NOx to N2 at low temperatures is achieved via redox reaction on the surface of the catalyst. Because the process has many advantages such as
ª Materials Research Society 2019
high denitration efficiency, low activation temperature and low cost, it has become the main strategy for denitration in the world. At present, the catalysts applied in the SCR denitration process mainly use V2O5–WO3 as the main active component, and TiO2 is used as the carrier. These catalysts present
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