铁铈复合氧化物催化剂SCR脱硝反应动力学研究

Kinetic study on the selective catalytic reduction of NO with NH_3 over iron-cerium mixed oxide

利用共沉淀法制备了铁铈复合氧化物催化剂,在积分实验系统上考察了NO初始浓度、NH3/NO比及O2浓度对其SCR脱硝活性的影响;并借助微分系统探讨了其SCR脱硝的催化反应动力学,构建了铁铈复合氧化物催化剂的催化脱硝反应动力学模型。实验结果表明,NO初始浓度越高,每克催化剂的NO转化率越高;随着NH3/NO比的增加,NO转化率先迅速增加后趋势减缓,最终趋于稳定;O2在NH3-SCR反应中起着重要的作用;在175～225℃下,Fe0.95Ce0.05Oz催化剂的NO和NH3反应级数分别为1级和0级,O2的反应级数接近0.5级,该反应的表观活化能为42.6 kJ/mol。

Iron-cerium mixed metal oxide （Fe0.95 Ce0.05 O2 ） was prepared through co-precipitation method and used as the catalyst in the selective catalytic reduction of NO with NH3 （ NH3-SCR） ; the effects of initial concentration of NO, molar ratio of NHJNO and 02 concentration on its NH3-SCR activity were investigated in an integral reactor at steady-state and the kinetics were considered in a differential reactor. The results indicated that the amount of NO converted over per unit catalyst increases with the initial concentration of NO; with the increase of NH3/NO mol ratio, NO conversion is firstly increased sharply and then gradually reaches a stable value; 02 in the flue gas also plays an important role in the NH3-SCR reaction. The NH3-SCR reaction over Fe0.95Ce0.0502 exhibits first-order with respect to NO, zero-order to NH3, and nearly 0.5-order to 02 at 175 - 275℃ ; the apparent activation energy is 42.6 kJ/mol.