Abstract

Cu-SSZ-13 catalyst, as the most popular selective catalytic reduction on filter (SCRF) catalyst in diesel exhaust purification, may suffer from severe alkali deposition derived from engine oil, urea solution and biodiesel fuel. These accumulated deposits inevitably affect both of the NO_x reduction and soot oxidation reactions. Unlike deactivation effect of alkali impurities on Cu-SSZ-13 catalyst for NH₃-SCR process, which has been extensively studied and well documented, the impact of alkali deposition on soot oxidation over SCRF catalyst is still poorly understood. Herein, we reported the influence of potassium salts deposition on soot oxidation of Cu-SSZ-13 catalyst. Compared with the fresh Cu-SSZ-13, these K-impregnated catalysts show promoted activities toward soot oxidation with the promotion effect of K₂SO₄ > K₂CO₃ > K₃PO₄. The generated copper compounds instead of potassium salts are found to be responsible for the enhanced catalytic activity. The NO oxidation over the K₂CO₃-impregnated catalyst is accelerated by CuO_x clusters, resulting in a low ignition temperature toward soot oxidation in the presence of NO_x. Contrarily, K₂SO₄- and K₃PO₄-impregnated catalysts show higher ignition temperature values because the generated copper sulfates and phosphates present weakened NO oxidation activities especially in the low-temperature region. This work provides new insight into understanding the affecting mechanism of alkali impurities on SCRF catalysts.

Graphic Abstract

The generated Cu species induced by the deposition of different potassium salts, rather than alkali species themselves, are responsible for the promoted soot oxidation activity of the K-impregnated Cu-SSZ-13 as a SCRF catalyst.

中文翻译：

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沉积钾盐对SCRF催化剂Cu-SSZ-13烟So氧化活性的影响

摘要

Cu-SSZ-13催化剂是柴油机尾气净化中最流行的选择性过滤还原（SCRF）催化剂，可能会因发动机油，尿素溶液和生物柴油燃料而产生严重的碱沉积。这些累积的沉积物不可避免地影响NO _x还原和烟灰氧化反应。不同于碱性杂质对Cu-SSZ-13 NH ₃催化剂的失活作用-SCR过程，已被广泛研究和充分记录，碱沉积对SCRF催化剂上烟尘氧化的影响仍然知之甚少。在这里，我们报道了钾盐沉积对Cu-SSZ-13催化剂烟so氧化的影响。与新鲜的Cu-SSZ-13相比，这些含K的催化剂显示出对烟灰氧化的促进活性，并具有K ₂ SO ₄  > K ₂ CO ₃  > K ₃ PO ₄的促进作用。发现产生的铜化合物而不是钾盐负责增强的催化活性。CuO促进K ₂ CO ₃浸渍催化剂上的NO氧化_x团簇，导致在存在NO _x的情况下朝着烟灰氧化的低着火温度。相反，K ₂ SO ₄和K ₃ PO ₄浸渍的催化剂显示出较高的着火温度值，因为生成的硫酸铜和磷酸盐具有减弱的NO氧化活性，特别是在低温区域。这项工作为了解SCRF催化剂上碱杂质的影响机理提供了新的见解。

图形摘要

由不同钾盐的沉积而不是碱金属本身引起的生成的铜物质，是作为SCRF催化剂的K浸渍Cu-SSZ-13烟灰氧化活性提高的原因。