Facile synthesis of CuSO4/TiO2 catalysts with superior activity and SO2 tolerance for NH3-SCR: physicochemical properties and reaction mechanism
Facile synthesis of CuSO4/TiO2 catalysts with superior activity and SO2 tolerance for NH3-SCR: physicochemical properties and reaction mechanism
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DOI：
10.1039/c6cy02626e
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发表时间：
2017-04
影响因子：
5
通讯作者：
Yanke Yu;Jifa Miao;Jinxiu Wang;Chi He;Jinsheng Chen
中科院分区：
文献类型：
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作者：
Yanke Yu;Jifa Miao;Jinxiu Wang;Chi He;Jinsheng Chen
采用固相浸渍法制备了一系列不同CuSO_4负载量（0- 20wt%）的CuSO_4/TiO_2二元氧化物催化剂。通过N2吸附/脱附、XRD、拉曼、NH3-TPD、NO-TPD、H2-TPR、XPS和原位DRIFTS等手段对催化剂的物化性质和NO反应路线进行了表征。CuSO 4含量对催化剂活性有显著影响。较高的CuSO 4负载量有利于CuSO 4与TiO 2的固相反应，促进亚硫酸盐中心和弱酸中心的形成，并明显提高了催化剂在340 °C以下的活性。然而，在高于340 °C的温度下，NH3氧化随着CuSO 4负载量的增加而增加，并且当CuSO 4负载量高于10wt%时导致NOx转化率下降。因此，具有10wt%CuSO4负载量的样品呈现最宽的温度窗口，并且还显示出优异的耐SO2和H2O性。在催化剂上形成了Bronsted酸中心和刘易斯酸中心。硫酸根和亚硫酸根的S-OH是形成Bronsted酸中心的主要原因。CuSO 4/TiO 2上的NH3-SCR反应遵循Eley-Rideal机理：NH3首先以NH 4+和NH3的形式吸附在Bronsted和刘易斯酸中心上，然后与气态NO和O2反应生成N2和H2O。
A series of CuSO4/TiO2 binary oxide catalysts with different CuSO4 loadings (0–20 wt%) were prepared by a facile solid state impregnation protocol. The physicochemical properties of the catalysts and the NO reaction route were extensively characterized via N2 adsorption/desorption, XRD, Raman, NH3-TPD, NO-TPD, H2-TPR, XPS, and in situ DRIFTS. The CuSO4 content had significant influence on catalytic activity. High CuSO4 loading favored the solid reaction between CuSO4 and TiO2, promoted the formation of sulfite and weak acid sites, and obviously increased the activity at temperatures below 340 °C. However, at a temperature higher than 340 °C, NH3 oxidation increased with CuSO4 loading and caused NOx conversion to decrease when the CuSO4 loading was higher than 10 wt%. Thus, the sample with 10 wt% CuSO4 loading presented the broadest temperature window and it also showed an excellent resistant to SO2 and H2O. Both Bronsted and Lewis acid sites were formed on the catalyst. S–OH of sulfate and sulfite were the main reason for formation of Bronsted acid sites. NH3-SCR reaction on CuSO4/TiO2 followed the Eley–Rideal mechanism: NH3 first adsorbed on Bronsted and Lewis acid sites as NH4+ and NH3, then reacted with gaseous NO and O2 to form N2 and H2O.