氧化锆形态对Pd / ZrO <sub>2</sub>上苯酚加氢脱氧的影响<sub></sub>,ACS Catalysis

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氧化锆形态对Pd / ZrO ₂上苯酚加氢脱氧的影响
ACS Catalysis ( IF 11.3 ) Pub Date : 2015-11-17 00:00:00 , DOI: 10.1021/acscatal.5b01501
Priscilla M. de Souza _{1,

2} , Raimundo C. Rabelo-Neto ₁ , Luiz E. P. Borges ₂ , Gary Jacobs ₃ , Burtron H. Davis ₃ , Uschi M. Graham ₃ , Daniel E. Resasco ₄ , Fabio B. Noronha _{1,

2}

Affiliation

这项工作研究了氧化锆结构对Pd / ZrO ₂催化剂在300°C和1 atm下使用固定床反应器进行苯酚加氢脱氧性能的影响。苯是Pd / t-ZrO ₂上方的主要产物，而在Pd / m-ZrO ₂上方则明显形成了环己酮。另一方面，Pd / m，t-ZrO ₂表现出中间行为。吸附的吡啶，NH ₃ -TPD的DRIFTS和环己醇反应的脱水表明，Pd / t-ZrO ₂催化剂比Pd / m-ZrO ₂和Pd / m，t-ZrO ₂表现出更高的亲氧位点密度。。这促进了脱氧产物的形成。但是，可能不排除涉及将环己醇脱水成环己烯，然后再脱氢成苯的机理。钯/锆₂催化剂随着生产时间的延长而显着失活。环己烷的脱氢和环己醇的脱水的结果表明，在苯酚反应的加氢脱氧过程中，Pd的粒径增加，亲氧性位点的密度降低。另外，在反应条件下的DRIFTS光谱表明，在反应过程中苯氧基和中间物种对亲氧位点的覆盖增加。Pd颗粒的增长可能是金属-载体界面损失的原因，该损失逐渐抑制了被吸附物质在金属-载体边界的周转能力。

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Effect of Zirconia Morphology on Hydrodeoxygenation of Phenol over Pd/ZrO2

This work studies the effect of zirconia structure on the performance of Pd/ZrO₂ catalysts for hydrodeoxygenation of phenol at 300 °C and 1 atm using a fixed bed reactor. Benzene was the major product over Pd/t-ZrO₂, while significant formation of cyclohexanone was observed over Pd/m-ZrO₂. On the other hand, Pd/m,t-ZrO₂ exhibited intermediary behavior. DRIFTS of adsorbed pyridine, NH₃-TPD, and the dehydration of the cyclohexanol reaction revealed that the Pd/t-ZrO₂ catalyst exhibits a higher density of oxophilic sites than Pd/m-ZrO₂ and Pd/m,t-ZrO₂. This promoted the formation of deoxygenated products. However, a mechanism involving dehydration of cyclohexanol to cyclohexene, followed by dehydrogenation to benzene, may not be ruled out. Pd/ZrO₂ catalysts significantly deactivated as a function of time on stream. Results of dehydrogenation of cyclohexane and dehydration of cyclohexanol indicate that the Pd particle size increased and the density of oxophilic sites decreased during the hydrodeoxygenation of the phenol reaction. In addition, the DRIFTS spectra under reaction conditions demonstrated that the coverage of oxophilic sites by phenoxy and intermediate species increased during the reaction. The growth of Pd particles is likely responsible for the losses in the metal–support interface that gradually inhibits the ability of the adsorbed species to turnover at the metal–support boundary.

更新日期：2015-11-17

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