title: Activity and leaching features of zinc-aluminum ferrites in catalytic wet oxidation of phenol.
abstract: A series of ZnFe(2-x)Al(x)O(4) spinel type catalysts prepared by sol-gel method have been characterized and tested for catalytic wet oxidation (CWO) of phenol with pure oxygen. The iron species existed in these materials as aggregated iron oxide clusters and Fe3+ species in octahedral sites. With a decrease in iron content the concentration of the first iron species decreased and the latter increased. Complete phenol conversions and high chemical oxygen demand (COD) removals were obtained for all catalysts during phenol degradation at mild reaction conditions (160 degrees C and 1.0 MPa of oxygen pressure). Increasing with the concentration of Fe3+ species in octahedral sites, induction period became significantly shortened. After phenol was completely degraded, the concomitant recycling of the leaching Fe3+ ions back to the catalyst surface was observed, and in this case it is possible to perform successful CWO reactions with some cycles. It is also suggested that during the reaction the Fe3+ cations coordinated in octahedral sites in the ZnFe(2-x)Al(x)O(4) catalysts are resistant to acid leaching, but the reduced Fe2+ cations become much more labile, leading to increased Fe leaching.
authors.affiliation: Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
authors.forename: Aihua
authors.initials: A
authors.lastname: Xu
authors.forename: Min
authors.initials: M
authors.lastname: Yang
authors.forename: Ruiping
authors.initials: R
authors.lastname: Qiao
authors.forename: Hongzhang
authors.initials: H
authors.lastname: Du
authors.forename: Chenglin
authors.initials: C
authors.lastname: Sun
mesh_terms: D000535:Aluminum; D002384:Catalysis; D004785:Environmental Pollutants / Q000737:chemistry*; D052918:Environmental Restoration and Remediation / Q000379:methods*; D005290:Ferric Compounds / Q000737:chemistry*; D007501:Iron; D010084:Oxidation-Reduction; D019800:Phenol / Q000737:chemistry*; D013329:Structure-Activity Relationship; D014867:Water; D015032:Zinc
chemical_list: D004785:Environmental Pollutants; D005290:Ferric Compounds; D014867:Water; C001215:ferrite; D019800:Phenol; D000535:Aluminum; D007501:Iron; D015032:Zinc