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研究报告

叶栋,曲瑞陽,翁卫国,张涌新,吴卫红,宋浩,郑成航,高翔.Fe₂O₃添加对钛基SCR催化剂表面硫酸氢铵分解行为的影响规律[J].环境科学学报,2018,38(5):1774-1782

Investigation of the effect of Fe₂O₃ addition on the decomposition behavior of NH₄HSO₄ on the TiO₂-based SCR catalyst surfaces

基金项目：国家重点研发计划项目（No.2016YFC0203701）；国家NSFC-浙江两化融合基金（No.U1609212）；环保公益性行业科研专项（No.201509012）

摘要：采用共沉淀法合成了TiO₂及TiO₂-Fe₂O₃载体，并对硫酸氢铵与上述载体之间的相互作用及硫酸氢铵的具体分解行为进行了研究.结果表明，催化剂载体表面含硫官能团主要以双齿硫酸盐的形式存在，含氮官能团以铵根离子的形式存在.当硫酸氢铵沉积于催化剂载体表面时，由于硫酸根离子具有较强的电负性，Ti原子及Fe原子处于电子缺失状态.对于TiO₂载体，硫酸根离子主要与Ti原子相连；而对于TiO₂-Fe₂O₃载体，Ti原子及Fe原子均为硫酸根离子主要的附着位点.采用热分析方法及原位红外对硫酸氢铵在TiO₂及TiO₂-Fe₂O₃载体表面的分解行为进行了研究，发现铁氧化物的添加显著促进了硫酸氢铵在低温区间内的分解行为；与铵根离子相比，硫酸根离子具有更高的热稳定性.催化剂稳定性测试结果表明，铁氧化物的添加显著提高了低温抗硫抗水性能，为实现低温SCR技术的工业应用提供了理论基础.

Abstract：In this study, TiO₂ and TiO₂-Fe₂O₃ supports used for the selective catalytic reduction of NO with NH₃ were synthesized using the co-precipitation method. The interactions between NH₄HSO₄ and these supports, together with the detailed decomposition behavior of NH₄HSO₄ on the series catalyst supports, were investigated. On the catalyst support surfaces, sulfate species existed as bidentate SO₄^2- and N-containing functional groups were presented in the form of NH₄⁺. Given that NH₄HSO₄ was deposited on the catalyst surfaces, Ti and Fe atoms were present in an electron-deficit state because of the stronger electronegativity of SO₄^2-. In the case of TiO₂ support, Ti atoms functioned as a reservoir for the accommodation of sulfate anions. While for TiO₂-Fe₂O₃ mixed support, both Ti and Fe atoms sometimes interacted with sulfate species. Compared with NH₄HSO₄ deposited on the Ti support surface, the decomposition behavior of NH₄HSO₄ was promoted through adding Fe₂O₃. In situ DRIFTS results demonstrated that SO₄^2- possessed a higher thermal stability than NH₄⁺. Finally, the deactivation of catalysts by SO₂ and H₂O could be impeded in a certain extent by introducing Fe₂O₃, suggesting that Fe₂O₃-modified catalysts would be typically used in the low-temperature SCR systems in the future.