Slow progress in discovering new catalysts to circumvent the problem of ammonium bisulfate (NH₄HSO₄, ABS) poisoning has hindered further development of selective catalytic reduction (SCR) technology of NO_x with ammonia (from numerous industrial processes) in afterburning systems at temperatures below dew point of ABS (typically between 280 °C and 320 °C). Recently, we have explored the use of atomically dispersed Mo species on TiO₂ particles (hereafter denoted as MoO₃/TiO₂) as highly efficient catalyst for NH₃-SCR reaction. In the present study, it will be shown that this type of catalyst is highly resistant to ABS poisoning for NH₃-SCR reaction, overcoming a major issue afflicting the application of commercial V₂O₅-WO₃/TiO₂ catalyst at temperatures below the dew point of ABS. Aberration-corrected scanning transmission electron microscopy (STEM) suggests that most of the Mo species are present in atomically dispersed form in the MoO₃/TiO₂ catalyst. SO₂ oxidation measurements show that the MoO₃/TiO₂ catalyst exhibits a substantially lower SO₂ oxidation rate compared to the commercial V₂O₅-WO₃/TiO₂, mitigating ABS formation. Furthermore, decomposition of ABS on MoO₃/TiO₂ surface is found to be extremely facile. Temperature-programmed surface reaction (TPSR) with NO shows that the decomposition temperature of ABS over MoO₃/TiO₂ is 70 °C lower than that found on the commercial V₂O₅-WO₃/TiO₂ catalyst. Our investigations provide valuable information for the development of NH₃-SCR catalysts with exceptional resistance to ABS poisoning for NO_x emission control.

在发现新催化剂以规避硫酸氢铵 (NH ₄ HSO ₄ , ABS) 中毒问题方面进展缓慢，阻碍了在温度下后燃烧系统中用氨（来自众多工业过程）选择性催化还原 (SCR) 技术的 NO _{x 的}进一步发展低于 ABS 的露点（通常在 280 °C 和 320 °C 之间）。最近，我们探索了在 TiO ₂颗粒上使用原子分散的 Mo 物种（以下表示为 MoO ₃ /TiO ₂）作为 NH ₃ -SCR 反应的高效催化剂。在本研究中，将表明这种类型的催化剂对 NH _{3 的}ABS 中毒具有很强的抵抗力-SCR反应，克服了在低于ABS露点的温度下影响商业V ₂ O ₅ -WO ₃ /TiO ₂催化剂应用的主要问题。像差校正扫描透射电子显微镜 (STEM) 表明，大多数 Mo 物质以原子分散的形式存在于 MoO ₃ /TiO ₂催化剂中。SO ₂氧化测量表明，与商用 V ₂ O ₅ -WO ₃ /TiO ₂相比，MoO ₃ /TiO ₂催化剂表现出明显较低的 SO ₂氧化速率, 减轻 ABS 的形成。此外，发现 ABS 在 MoO ₃ /TiO ₂表面上的分解极其容易。与 NO 的程序升温表面反应 (TPSR) 表明，ABS 在 MoO ₃ /TiO ₂上的分解温度比商业 V ₂ O ₅ -WO ₃ /TiO ₂催化剂上的分解温度低 70°C 。我们的研究为开发 NH ₃ -SCR 催化剂提供了有价值的信息，该催化剂具有卓越的抗 ABS 中毒能力，用于控制NO _x排放。