SO₂和O₃对锰-钴催化剂氧化NO的影响研究

丝梦 沈伯雄

摘要 采用浸渍法制备了15%Mn-Co（2∶1）/TiO2催化剂，研究其催化氧化NO的性能，重点研究了SO2和O3对NO催化氧化性能的影响。性能测试和傅里叶变换原位红外光谱分析结果表明，SO2在催化剂表面以物理和化学吸附作用为主，生成的硫酸盐物种占据了催化剂活性位点，抑制了催化剂对NO的吸附和催化氧化。O3能够促使硫酸盐物种向覆盖力较弱的吸附态转变，有利于释放催化剂表面活性位点。此外，O3能够明显促进单配位硝酸盐的生成，特别是在低温条件下，有利于硝酸盐物种释放出气态NO2。因此，O3能够提高催化剂抗SO2的性能，从而提高其对NO的催化氧化能力。

关 键 词 NO氧化;臭氧;抗硫性能;锰-钴催化剂;原位红外光谱;机理分析

中图分类号 X701.3;O643.36     文獻标志码 A

文章编号：1007-2373（2021）06-0069-08

Abstract 15%Mn-Co（2∶1）/TiO2 catalyst was prepared by impregnation method to study the catalytic oxidation of NO， with emphasis on the influences of SO2 and O3 on the performance of NO catalytic oxidation by the catalyst.The results of activity experiments and in situ FTIR showed that， the physical and chemical adsorption of SO2 on the catalyst surface was dominant， and the generated sulfate species occupied the active sites， which inhibited the adsorption and catalytic oxidation of NO by the catalyst. However， the presence of O3 can promote the transformation of sulfate species to a weak adsorption state， which was conducive to the release of active sites on the catalyst surface. In addition， O3 can significantly promote the formation of monodentate nitrates， especially at low temperature， which was conducive to the release of gaseous NO2 by nitrate species. Therefore， O3 can improve the tolerance of 15%Mn-Co（2∶1）/TiO2 catalyst to SO2，thus improving its catalytic oxidation performance of NO.

Key words NO oxidation; ozone; sulfur resistance; manganese-cobalt catalyst; in situ FTIR; mechanism analysis

0 引言

随着工业技术的发展，化石燃料燃烧造成的空气污染已经成为不可回避的话题。电力、钢铁、冶金、焦炭等行业以及我国北方冬季供暖的煤炭、天然气燃烧均会产生大量氮氧化物（NOx）、SO2、粉尘颗粒以及挥发性有机物等空气污染物。对我国京津冀地区在2017—2018年供暖季PM2.5主要组分占比进行统计，硝酸盐已取代硫酸盐成为细颗粒污染物中最主要的二次无机组分[1]。这意味着相较以往强调SO2的排放控制，NOx的排放控制越发具有紧迫性和重要性。在过去的二十年里，人们对控制NOx排放技术的研究以选择性催化还原（SCR）和选择性非催化还原（SNCR）技术为主[2-4]。但反应温度要求较高、还原剂NH3的逃逸等问题依然存在。并且烟气中的SO2会与还原剂NH3反应生成（NH4）2SO4和（NH4）HSO4，造成设备腐蚀、烟气管道堵塞及催化剂减活等[5]。……