Wet oxidation of phenol on Ce{sub 1{minus}x}Cu{sub x}O{sub 2{minus}{delta}} catalyst

Journal Article · Sat May 15 04:00:00 EDT 1999 · Journal of Catalysis

DOI:https://doi.org/10.1006/jcat.1999.2422· OSTI ID:354380

Hocevar, S; Batista, J ^[1]; Levec, J ^[1]

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1. National Inst. of Chemistry, Ljubljana (Slovenia). Lab. of Catalysis and Chemical Reaction Engineering

Ce{sub 1{minus}x}Cu{sub x}O{sub 2{minus}{delta}} catalysts with 0.05 < x < 0.20 for catalytic wet oxidation of phenol in aqueous solutions have been synthesized using the coprecipitation method. The three most important synthesis parameters, the concentration of the mixed metal salt solution, the rate of coprecipitant addition and the stirrer speed during coprecipitation, were optimized with central composite design using the catalytic activity as a response function. The catalytic activity strongly depends on stirrer speed during coprecipitation. A high mutual dispersion of copper oxide and ceria, having the average crystallite size of about 9 nm, enhances solid solution formation. The unit cell parameter of ceria decreases when the overall concentration of copper in the catalyst increases, most probably obeying Vegard`s law. The catalysts proved to be very stable in hydrothermal reaction conditions at low pH values. After 5 h of reaction in the semibatch CST reactor less than 100 ppm of Cu was leached out of catalyst samples that were calcined in a flow of air for 2 h above 1033 K, and only a very low quantity of carbonaceous deposits were formed on the surface of the catalysts (0.6 wt%). The kinetics of phenol degradation could be interpreted by an equation valid for homogeneous autocatalytic reactions, in which the rate constant depends linearly on the heterogeneous catalyst (Cu) concentrations. This demonstrates that the reaction proceeds through a heterogeneous-homogeneous radical-branched chain mechanism.

• OSTI ID: 354380
• Journal Information: Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 1 Vol. 184; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
CATALYSTS
CATALYTIC EFFECTS
CERIUM OXIDES
CHEMICAL PREPARATION
CHEMICAL REACTION KINETICS
COPPER OXIDES
PHENOL
WASTE WATER
WATER TREATMENT
WET OXIDATION PROCESSES