This work investigated the effect of the addition of a second metal (Cu, Ag, Zn, Sn) on the performance of Pd/ZrO₂ catalyst for HDO of phenol at 573 K in the gas phase. The incorporation of dopants resulted in the formation of Pd–X (Cu, Ag, Zn) alloys, which reduced the reaction rate for HDO and increased the selectivity to hydrogenation products (cyclohexanone and cyclohexanol). For PdSn/ZrO₂, alloying was also observed but tin oxide was still present on the surface after reduction at 773 K. For Pd/ZrO₂ and PdSn/ZrO₂, the oxophilic sites represented by Zr and Sn cations promotes the hydrogenation of the carbonyl group of the keto-tautomer intermediate formed, producing benzene as the main product. All catalysts significantly deactivated during the reaction but the deactivation degree depended on the type of the metal. Pd/ZrO₂ and PdZn/ZrO₂ and PdAg/ZrO₂ exhibited approximately the same deactivation degree. However, the loss of activity was less pronounced for PdSn/ZrO₂ catalyst. Pd dispersion significantly decreased during the reaction, indicating that the sintering of Pd particles is one of the causes for catalyst deactivation.

这项工作研究了添加第二种金属（Cu，Ag，Zn，Sn）对Pd / ZrO ₂催化剂在573 K气相中苯酚HDO性能的影响。掺杂剂的掺入导致形成Pd–X（铜，银，锌）合金，从而降低了HDO的反应速率并提高了对氢化产物（环己酮和环己醇）的选择性。对于PdSn / ZrO ₂，也观察到合金化，但在773 K还原后表面仍存在氧化锡。对于Pd / ZrO ₂和PdSn / ZrO ₂，以Zr和Sn阳离子为代表的亲氧性位点促进所形成的酮-互变异构体中间体的羰基氢化，从而产生苯作为主要产物。所有催化剂在反应过程中都会明显失活，但是失活程度取决于金属的类型。Pd / ZrO ₂和PdZn / ZrO ₂和PdAg / ZrO ₂表现出大致相同的失活度。然而，对于PdSn / ZrO ₂催化剂，活性的损失不太明显。反应期间Pd的分散度显着降低，表明Pd颗粒的烧结是催化剂失活的原因之一。