采用等体积浸渍法在不同温度下焙烧制备了一系列MnO_2-CeO_2/Zr_(0.25)Ti_(0.25)Al_(0.5)O_(1.75)整体式催化剂样品,并用低温N_2吸附-脱附、储氧量、X射线衍射、X射线光电予能谱和NH_3程序升温脱附等对催化剂进行了表征,考察了催化剂上NH_3选择性催化还原(SCR)NO的活性.结果表明,随着焙烧温度的升高,催化剂的比表面积和孔体积逐渐减小,平均孔径逐渐增大,储氧能力逐渐降低.在500～700℃焙烧时,催化剂主要以无定形或微晶的形式存在;在500℃焙烧时,催化剂表面Mn与载体之间的相互作用较强,表面酸量最高,有利于提高SCR活性.尽管在600和700℃焙烧的催化剂仍具有较高的SCR活性,且表现出一定的抗H_2O和SO_2性能.但活性有所下降.800℃焙烧后催化剂的活性显著降低.
The MnO_2-CeO_2/Zr_(0.25)Ti_(0.25)Al_(0.5)O_(1.75) monolith catalyst was prepared by the incipient wetness method. The influence of calcination temperature on the textural and structural properties as well as the catalytic activity for selective catalytic reduction (SCR) of NO by NH_3 was investigated by N_2 adsorption-desorption at low temperature. oxygen storage capacity (OSC), X-ray diffraction, X-ray photoelectron spectroscopy, and NH_3 temperature-programmed desorption. The results showed that the specific surface area, pore volume, and OSC of the catalyst decreased, while the average pore diameter increased with the increase of calcination temperature. The catalyst presented as amor-phous or crystallite when calcined in the temperature range of 500-700 oC. The catalyst calcined at 500 ℃ showed the largest surface acid amount and the strong interaction between the surface Mn and the support, which were beneficial to the SCR activity. The activity decreased with the increase of the calcination temperature. The activity was still considerable when the catalyst was calcined at 600 and 700 ℃, but the activity obviously decreased at 800 ℃.
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