Environmentally benign cerium-based catalysts are promising alternatives to toxic vanadium-based catalysts for controlling NO_x emissions via selective catalytic reduction (SCR), but conventional cerium-based catalysts unavoidably suffer from SO₂ poisoning in low-temperature SCR. We develop a strongly sulfur-resistant Ce₁₊₁/TiO₂ catalyst by spatially confining Ce atom pairs to different anchoring sites of anatase TiO₂(001) surfaces. Experimental results combined with theoretical calculations demonstrate that strong electronic interactions between the paired Ce atoms upshift the lowest unoccupied states to an energy level higher than the highest occupied molecular orbital (HOMO) of SO₂ so as to be catalytically inert in SO₂ oxidation but slightly lower than HOMO of NH₃ so that Ce₁₊₁/TiO₂ has desired ability toward NH₃ activation required for SCR. Hence, Ce₁₊₁/TiO₂ shows higher SCR activity and excellent stability in the presence of SO₂ at low temperatures with respect to supported single Ce atoms. This work provides a general strategy to develop sulfur-resistant catalysts by tuning the electronic states of active sites for low-temperature SCR, which has implications for practical applications with energy-saving requirements.

中文翻译：

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原子配对通过提高铈的最低未占据态来增强低温 SCR 的抗硫性


环境友好的铈基催化剂是有毒钒基催化剂的有前途的替代品，可通过选择性催化还原（SCR）控制 NO _x 排放，但传统的铈基催化剂不可避免地会受到 SO ₂ 低温SCR中毒。我们通过将 Ce 原子对空间限制在锐钛矿 TiO ₂ (001) 表面的不同锚定位点，开发了一种强抗硫性的 Ce ₁₊₁ /TiO ₂ 催化剂。实验结果与理论计算相结合表明，成对的Ce原子之间的强电子相互作用将最低未占据态提升到高于SO ₂ 的最高占据分子轨道（HOMO）的能级，从而具有催化惰性SO ₂ 氧化，但略低于 NH ₃ 的 HOMO，因此 Ce ₁₊₁ /TiO ₂ 对 NH ₃ SCR 需要激活。因此，Ce ₁₊₁ /TiO ₂ 在 SO ₂ 存在下在低温下相对于负载的单个 Ce 原子表现出更高的 SCR 活性和优异的稳定性。这项工作提供了通过调节低温SCR活性位点的电子态来开发抗硫催化剂的总体策略，这对具有节能要求的实际应用具有重要意义。