Abstract

A Pd/Al₂O₃ catalyst (Pd = 0.1 wt %) for ethanol conversion to butanol deactivates within 10 h of service, despite its high initial activity at 275°C. Probable deactivation mechanisms were explored, including poisoning of Pd/Al₂O₃ due to adsorption of by-products on Pd, sintering of Pd phases, leaching of Pd from the catalyst, changes in the Pd electronic state, changes in the catalyst’s porous structure, and blockage of Al₂O₃ active sites. The Pd/Al₂O₃ deactivation was found to be mainly caused by CO molecules that evolved during side reactions. These molecules can either block Pd active sites due to the formation of strong Pd–CO complexes, or enter a CO disproportionation reaction to form carbon deposits on Pd phases. The knowledge gained from this study can be used for the targeted modification of Pd/Al₂O₃ and the creation of selective systems operating stably in the presence of by-products.

中文翻译：

---

钯催化乙醇转化为丁醇的失活机理

摘要

尽管在275°C时具有很高的初始活性，但用于乙醇转化为丁醇的Pd / Al ₂ O ₃催化剂（Pd = 0.1 wt％）会在使用10小时内失活。探索了可能的失活机理，包括副产物在Pd上的吸附导致Pd / Al ₂ O _3的中毒，Pd相的烧结，Pd从催化剂中的浸出，Pd电子态的变化，催化剂多孔结构的变化，以及Al ₂ O ₃活性位点的阻塞。Pd / Al ₂ O ₃发现失活主要是由副反应过程中产生的CO分子引起的。这些分子可以由于形成强的Pd-CO络合物而阻止Pd的活性位点，或者进入CO歧化反应以在Pd相上形成碳沉积物。从这项研究中获得的知识可用于Pd / Al ₂ O ₃的目标修饰以及在副产物存在下稳定运行的选择性系统的创建。