利用 BET比表面测定和 X-射线衍射技术考察了掺杂 La或 Si的 Ag/ Al2 O3催化剂的热稳定性 ,并研究了富氧条件下 ,丙烯在这些催化剂上选择性还原 NO的活性 .结果表明 ,掺杂 L a或 Si能抑制 Al2 O3相变 ,使 γ- Al2 O3完全转化为 α- Al2 O3的温度升至 1 1 0 0℃以上 .相应地 ,延缓催化剂比表面下降 ,从活性角度来看 ,当焙烧温度为 1 1 0 0℃时 ,与掺杂 La或 Si相比 ,不掺杂 La或 Si的 Ag/ Al2 O3催化剂活性要低得多 ;当焙烧温度低于 1 0 0 0℃时 ,掺杂少量 L a(2 % La2 O3)对 Ag/ Al2 O3催化剂活性影响不大 ,但是 ,掺杂 Si(2 %或 8% Si O2 )或较高含量 La(8% La2 O3)会导致催化剂活性降低 .综合考虑热稳定性和富氧条件下的 NO还原活性 ,认为掺杂较低含量 La(2 % La2 O3)的 Ag/ Al2 O3催化剂性能最佳 . The thermal stability of Ag / Al 2 O 3 doped La or Si catalysts was investigated by BET surface area and X-ray diffraction. The catalytic activity of propylene in the selective reduction of NO was investigated under oxygen-rich conditions. Results It is shown that the doping of L a or Si can inhibit the phase transformation of Al 2 O 3 and the temperature of completely converting γ-Al 2 O 3 to α-Al 2 O 3 increases to above 110 ° C. Correspondingly, the specific surface area of ​​the catalyst is retarded, When the calcination temperature is 110 ° C, the activity of Ag / Al 2 O 3 without or with La or Si is much lower than that with La or Si. When the calcination temperature is lower than 100 ° C (2% or 8% Si O2) or La (8% La 2 O 3) doped with a small amount of La (2% La 2 O 3) did not affect the catalytic activity of Ag / Al 2 O 3. Which leads to the decrease of the activity of the catalyst.The Ag / Al 2 O 3 catalyst doped with La (2% La 2 O 3) with the lowest content is considered as the best in terms of thermal stability and NO reduction activity under oxygen-rich conditions.