MnOx／Al-SBA-15催化剂低温NH3选择性催化还原NO的原位红外研究

用原位红外分别进行了MnOx／Al-SBA-15催化剂上NH3和NO＋O2的吸附态和瞬态实验以及NH3＋NO＋02反应的稳态实验。结果表明，催化剂上存在着L酸位和B酸位，NH3吸附在催化剂上形成配位态的NH3和NH4＋，配位态的NH3能脱氢形成-NH2活性中间态。NO＋O2在催化剂上吸附形成硝酸盐类、硝基类和亚硝酸盐类。将NO＋O2通入预吸附NH3的催化剂中时，表面的配位态的NH3、NH4＋和-NH2都会减少直至消失，SCR反应显著。而将NH3通人预吸附NO＋O2的催化剂中时，只有硝基类和亚硝酸盐类减少，硝酸盐类基本不发生变化，SCR反应微弱。NH3＋NO＋O2稳态反应中，催化剂表面稳定存在着NH4＋和硝酸盐类，SCR反应显著。

DRIFT study of MnOx/Al-SBA-15 catalyst for low-temperature selective catalytic reduction of NO with NH3

Experiments on the adsorption and transient of NH3 and NO ＋ O2 as well as steacly reacuon O2 NH3 ＋ NO ＋ O2 on the MnOx/Al-SBA-15 catalyst were conducted by in situ DRIFTS. It indicated that both Lewis acid sites and Brensted acid sites existed on the catalyst. NH3 was adsorbed on the catalyst and formed coordina- ted NH3 and NH4. Coordinated NH3 could transform into active intermediate --NH2 species due to H-abstrac- tion. NO ＋O2 were adsorbed on the catalyst and formed nitrate, nitro and nitrite species. When NO ＋O2 were introduced into MnOx/Al-SBA-15 catalyst that preadsorbed with NH3, the consumption and disappearance of- NH2, coordinated NH3 and NH4 were observed. SCR reaction proceeded remarkably. After NH3 was introduced into the catalyst that preadsorbed with NO ＋O2, the nitro and nitrite species were consumed and nitrate almost remained stable. SCR reaction was unobvious. In the steady reaction of NH3 ＋ NO ＋ O2, noticeable SCR reaction and steady NH4＋ and nitrate species were detected.