碱金属化合物对V_2O_5/AC催化剂低温脱硝的影响

Influence of alkali metal compound on low-temperature NH_3-SCR of NO over V_2O_5/AC catalyst

研究了碱金属化合物(K2SO4)对活性炭(AC)担载五氧化二钒(V2O5)组成的V2O5/AC催化剂的低温脱硝活性的影响。发现在V2O5/AC催化剂表面负载碱金属化合物(K2SO4)后其脱硝活性大大降低。用等体积浸渍法制备了V2O5/AC催化剂和Kx-V2/AC(x=0.5,1,2)催化剂。采用5种模型对动力学实验数据进行关联。结果显示,无论V2O5/AC催化剂是否负载K2SO4,Eley-Rideal模型均比其他模型可更好地描述SCR脱硝反应,碱金属化合物(K2SO4)的存在提高了反应活化能,但并不改变反应机理。

The influence of alkali metal compound（K2SO4）on kinetics of low-temperature SCR of NO by NH3 over V2O5（vanadium pentoxide）/AC（activated carbon）catalyst was investigated.The reaction activity decreased obviously when doping the V2O5/AC catalyst with alkali metal compound.The V2O5/AC and Kx-V2/AC（x=0.5,1,2）catalysts were prepared by the pore volume impregnation method.First,the influence of internal and external diffusions on the intrinsic kinetics experiment was eliminated.Then NH3 SCR experiments with different NO-to-NH3 ratios at various temperatures were carried out to test the model.Both the mechanical（i.e.Eley-Rideal model,Langmuir-Hinshelwood model,and Mars-van Krevelen model）and empirical（i.e.first-order model and power-rate law model）models were used to correlate the experimental data.The results showed that the Eley-Rideal model could well describe the SCR of NO by NH3 over V2O5/AC catalyst than other models whether alkali metal compound was doped in the V2O5/AC catalyst or not.The presence of alkali metal compound increased the reaction activation energy,but not the reaction mechanism.