Abstract:

The high activity and durability of three-way catalysts are key factors allowing vehicle exhaust emission to meet the increasingly stringent standards. However, SO₂ in exhaust gas is easily adsorbed by the three-way catalysts, leading to their deactivation. Cu/CeZrO₂/γ-Al₂O₃ and Cu/CeZrSnO₂/γ-Al₂O₃ catalysts were prepared by an impregnation method and tested for three-way catalytic performance and SO₂ resistance. The results showed that the Sn-doped catalysts exhibited high three-way catalytic performance and SO₂ resistance. A combination of XRD, H₂-TPR, O₂-TPD, XPS, SO₂-TPD and TG characterization confirmed that Sn doping induced the generation of abundant Ce³⁺ and more oxygen vacancies, and accelerated the lattice oxygen migration, which led to the participation of a large amount of surface adsorbed oxygen in the catalytic reaction. In addition, Sn doping contributed to the generation of unsaturated sites that could accept electrons from Cu⁺, thus promoting the formation of Cu²⁺. Moreover, Cu²⁺ as the active site of the three-way catalytic reaction, had a high adsorption energy when it was in contact with SO₂, which effectively attenuates the adsorption of SO₂ on Cu/CeZrSnO₂/γ-Al₂O₃, and further protects the active component of three-way catalyst from sulfurization while improving the catalytic efficiency.

Key words: catalyst, reactivity, adsorption, Sn doping, SO₂ resistance

摘要：

三效催化剂的高活性和耐用性是满足日益严格的汽车尾气排放标准的关键因素。然而，尾气中的二氧化硫容易被三效催化剂吸附，导致催化剂失活。本文采用浸渍法制备了Cu/CeZrO₂/γ-Al₂O₃和Cu/CeZrSnO₂/γ-Al₂O₃催化剂，并对其进行了三效催化性能和SO₂抗性测试。结果表明，掺杂Sn的催化剂展现出更高的三效催化性能和二氧化硫抗性。结合XRD、H₂-TPR、O₂-TPD、XPS、SO₂-TPD和TG表征证实，Sn掺杂诱导产生了丰富的Ce³⁺和更多的氧空位，并加速了晶格氧迁移，使得大量表面吸附氧参与了催化反应。此外，Sn的掺杂有助于产生不饱和位点，可以接受来自Cu⁺的电子转移，从而促进了Cu²⁺的形成。并且Cu²⁺作为三效催化反应的活性位点，它和SO₂接触进行吸附时具有较高的吸附能，有效减弱了SO₂在Cu/CeZrSnO₂/γ-Al₂O₃上的吸附，在提高三效催化剂催化效率的同时，进一步保护了活性组分免受硫化作用，使其抗性提高。

关键词: 催化剂, 活性, 吸附, Sn掺杂, SO₂抗性