Preparing and characterizing an optimal supported ceria catalyst for the catalytic wet air oxidation of phenol

Autor: Ching-Huei Wang, Jing-Song Chang, Lizone Chang, I-Pin Chen, Shiow-Shyung Lin
Rok vydání: 2004
Předmět:
Zdroj: Applied Catalysis B: Environmental. 50:49-58
ISSN: 0926-3373
DOI: 10.1016/j.apcatb.2003.12.019
Popis: The activity of several supported ceria catalysts for the catalytic wet air oxidation of phenol was investigated using an autoclave reactor. Results indicated that the support and the Ce content are both important factors affecting phenol conversion, whereas BET surface area had no appreciable effect. CeO 2 /γ-Al 2 O 3 was found to be the most active catalyst among the five tested. This superior activity was verified by O 2 -temperature programming desorption (O 2 -TPD), showing that CeO 2 /γ-Al 2 O 3 had the most exchangeable structure O 2 (capping O 2 ), and by H 2 -temperature programming reduction (H 2 -TPR), showing that it had the highest H 2 consumption (the most H 2 -reducible Ce species in the catalyst). For the CeO 2 /γ-Al 2 O 3 catalyst, the optimal Ce content was about 20 wt.%. X-ray diffraction (XRD) analysis and evaluation of full width at half maximum (FWHM, 2 θ =28.5°) of the XRD pattern showed that formation of larger crystals of CeO 2 at Ce content above 20 wt.% caused a decrease in the catalytic activity of CeO 2 /γ-Al 2 O 3 . The superior activity of CeO 2 /γ-Al 2 O 3 at 20 wt.% Ce content was confirmed by O 2 -TPD. The results of O 2 -TPD and H 2 -TPR of CeO 2 /γ-Al 2 O 3 with various Ce contents showed that not all the H 2 -reducible Ce species were associated with capping O 2 . Using the optimal CeO 2 /γ-Al 2 O 3 catalyst (loading 3.0 g/l), about 100% phenol conversion and 80% chemical oxygen demand (COD) removal was achieved after 2 h reaction at 180 °C and 1.5 MPa O 2 partial pressure. Although the efficacy of CeO 2 /γ-Al 2 O 3 is somewhat less than that of pure CeO 2 , the much lower cost of the former renders it a feasible catalyst for the catalytic wet air oxidation (CWAO) of phenol.
Databáze: OpenAIRE
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