Formed Zirconia Carriers

Te, Mure; Dahar, Steve; Koradia, Pramod; Ono, Yaichiro

doi:10.1016/b978-0-444-53202-2.50022-1

Cited by 1 publication

(2 citation statements)

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“…The relationship between the zirconia structure and acidity is controversial in the literature. Many authors have found a higher amount of acid sites for monoclinic ZrO 2 compared to the tetragonal ZrO 2 . ,, However, the opposite was observed for Te et al evaluating Saint-Gobain Norpro zirconia carriers . In this case, the values of adsorbed NH 3 were 1.2 μmol·m –2 (m-ZrO 2 ) and 2.2 μmol·m –2 (t-ZrO 2 ), which were quite similar to the ones obtained in our work.…”

Section: Results and Discussionsupporting

confidence: 87%

“…19,41,42 However, the opposite was observed for Te et al evaluating Saint-Gobain Norpro zirconia carriers. 43 In this case, the values of adsorbed NH 3 were 1.2 μmol•m −2 (m-ZrO 2 ) and 2.2 μmol•m −2 (t-ZrO 2 ), which were quite similar to the ones obtained in our work. Nonetheless, no significant difference on acidity was observed for ZrO 2 with different fractions of monoclinic and tetragonal phase.…”

Section: Methodssupporting

confidence: 89%

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

et al. 2015

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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.

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