钛白粉载体对选择性催化还原脱硝催化剂性能的影响

Effect of Titanium Dioxide Support on the Properties for Selective Catalytic Reduction De-NO_x Catalyst

钛白粉(TiO2)是钒钛类选择性催化还原(SCR)脱硝催化剂的载体,TiO2的晶型、比表面积、粒度、孔结构以及SO42-和P2O5含量直接影响所制备的SCR催化剂的性能。一般而言,TiO2的比表面积越大,以其制备的SCR催化剂的比表面积也越大,活性也较高;但对于纳米级TiO2,由于颗粒粒径太小,容易发生烧结,而且形成钒钛化合物,导致催化剂比表面积较载体明显下降,因而活性降低。锐钛型TiO2由于比表面积大和不易被硫化,较金红石型TiO2适合做载体。多孔结构的TiO2使得钒物种在载体表面处于高度分散状态,从而提高催化剂的活性。TiO2中本身含有的少量SO42-和P2O5有助于提高催化剂的性能。

Titanium dioxide （TiO2） is the support of selective catalytic reduction （SCR） De-NOx catalyst based on vanadium as active component. The crystal form, surface area, particle size, pore structure of TiO2 and the content of SO42- and P205 in TiO2 influence the performance of SCR De-NOx catalyst directly. Compared with titanium dioxide（TiO2）-rutile, titanium dioxide（TiO2） -anatase is the appropriate support due to its high specific surface area and resistance to sulfide. In general, higher surface area of TiO2 is beneficial to prepare catalyst. However, the surface area of catalyst is also related to the particle size of TiO2. Although high surface area of nanorneter TiO2 is used as support, the surface area of catalyst is still small because of sintering and the tormation of vanadium carbide. SCR De-NOx catalyst based on porous TiO2 is more effective owing to the good dispersion of vanadium oxide on TiO2. Small amount of SO42 and P205 introduced in TiO2 during the preparation of TiO2 can improve the De-NOx properties of catalyst.