Ceria-supported Pd nanoparticles are known to be efficient catalysts for vehicle exhaust purification, especially diesel oxidation. The exhaust often undergoes harsh conditions, suffering from high temperature up to ∼750 °C. These conditions cause Pd nanoparticles to sinter, losing the catalytic active sites. In addition, carbonate and sulfate species might be formed on the catalyst surface, blocking the active sites with degraded activity. Hydrothermal treatment on Pd/CeO₂ affects the catalyst structure, resulting in enhanced catalytic activity and durability for CO oxidation. CO conversion approached 100% at temperatures lower than 150 °C even in the presence of propylene or SO₂. The high activity for CO conversion changed little for longer reaction times and even for temperature fluctuations up to 850 °C. A promoting effect was obtained due to Pd redispersion and surface hydroxyl groups formed after the hydrothermal treatment. The redispersion was confirmed by TEM, EXAFS, XRD, in situ DRIFT, and CO chemisorption, and the suppression of surface-poisoning species was investigated using in situ DRIFT and TPD techniques.

中文翻译：

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水热处理对CO氧化Pd / CeO ₂催化剂活性和耐久性的促进作用

已知二氧化铈负载的Pd纳米颗粒是用于车辆排气净化（尤其是柴油氧化）的有效催化剂。排气经常经受恶劣的条件，遭受高达750°C的高温。这些条件导致Pd纳米颗粒烧结，失去催化活性位。此外，碳酸盐和硫酸盐类物质可能会在催化剂表面形成，从而阻止活性降低的活性中心。在Pd / CeO ₂上进行水热处理会影响催化剂的结构，从而提高催化活性和CO氧化的耐久性。即使在存在丙烯或SO ₂的情况下，在低于150°C的温度下，CO转化率也接近100％。对于较长的反应时间，甚至在高达850°C的温度波动下，CO转化的高活性几乎不变。通过Pd的再分散和水热处理后形成的表面羟基，获得了促进作用。通过TEM，EXAFS，XRD，原位DRIFT和CO化学吸附来确认重分散，并使用原位DRIFT和TPD技术研究了表面中毒物质的抑制作用。