硫酸化对In/SO4^2-／TiO2催化剂上CH4选择性催化还原NOx的促进机理  

Promotional Mechanism of Sulfation on Selective Catalytic Reduction of NO_x by Methane Over In/SO_4^(2-)/TiO_2

作　　者：荆国华[1,2] 李俊华[1] 杨栋[1] 郝吉明[1] 

机构地区：[1]清华大学环境科学与工程系,北京100084 [2]华侨大学环境科学与工程系,福建厦门361021

出　　处：《催化学报》2009年第5期459-464,共6页

基　　金：国家自然科学基金(20437010,20677034);国家高技术研究发展计划(863计划,2006AA060301)

摘　　要：考察了In/SO42-/TiO2(In/STi)催化剂上甲烷选择性催化还原(CH4-SCR)NOx的活性,分析了硫酸化对催化活性的促进作用.结果表明,硫酸化影响了In在催化剂表面的存在形态和CH4的活化产物,从而提高了催化剂活性.吡啶红外光谱分析表明,硫酸化后的STi载体可提供足够强度的B酸位,有利于活性中心InO+物种的形成.原位红外光谱分析表明,In/TiO2催化剂上CH4的活化产物为完全氧化的CO2和H2O,而硫酸化后的In/STi催化剂上CH4的活化产物为HCOO-,该物种被认为是CH4-SCR反应的重要中间体,它的生成为In/STi催化剂上CH4-SCR反应的速控步骤.The catalytic performance and the promotional mechanism of sulfation for selective catalytic reduction of NO by CH4 over sulfated titanium-loaded In （In/STi） were investigated. An enhancement of catalytic activity was obtained over the In/STi catalysts. Sulfation influenced the existent state of surface indium species and determined the activation species of CH4. Py-IR analysis showed that the sulfated In/STi catalyst had strong Brφnsted acid sites, which were beneficial to the formation of active InO^＋ species. DRIFTS studies further revealed the distinguish reaction intermediates of CH4-SCR of NO over the sulfated and unsulfated catalysts. On the In/TiO2 and TiO2 catalysts, the activation species of CH4 was the fully oxidized products of CO2 and H20, while on the STi and In/STi catalysts, HCOO-, the real reductant for CH4-SCR of NO, was detected as the main intermediate species. In addition, the formation of HCOO^- was the rate-determining step in CH4-SCR of NO on the In/STi catalyst.

关 键 词：甲烷 选择性催化还原 氮氧化物 固体超强酸 硫酸化 二氧化钛 

分 类 号：O643.32[理学—物理化学]