H2O2 Decomposition Activity Research Articles

A novel method for the preparation of Co Schiff-base functionalized MgAl layered double hydroxides

In order to immobilize neutral or positive metal complexes on layered double hydroxides (LDHs) and increase the amount of immobilized metal complexes, a novel strategy for the preparation of metal complex functionalized LDHs is proposed. This strategy involves exfoliating glycine-intercalated MgAl LDH in formamide under an ultrasound treatment, and then grafting silylated metal complexes on MgAl LDH nanosheets, as exemplified by immobilization of Co Schiff-base on MgAl LDHs. The prepared hybrids were characterized by XRD, AFM, FT-IR, TG, N2 adsorption–desorption and ICP techniques and their catalytic performances were investigated in H2O2 decomposition and styrene epoxidation with O2. The results showed that the hybrid prepared by this strategy had higher Co Schiff-base loading than the sample prepared by directly grafting silylated Co Schiff-base on glycine-intercalated MgAl LDHs due to the more accessible grafting sites on the exfoliated MgAl LDH nanosheets. Additionally, it was found that the grafted complexes could effectively impede the restack of LDH nanosheets after removal of the solvent. Thus, the prepared hybrid exhibited higher surface area and more accessible active centers, which made the prepared hybrid exhibit high catalytic activity in H2O2 decomposition and styrene epoxidation with O2. This work gives us a new way to prepare LDH hybrids functionalized with various metal complexes.

Assembly of transition metal ion on cellulose surface anchored with azo-Schiff base and its catalytic activity for H2O2 decomposition

To form polymer-supported catalysts, to eliminate excess H2O2 during wastewater treatment, the assembly of metal ion on cellulose was investigated. Cellulose was covalently grafted with reactive azo-Schiff base containing azo-conjugated system, 3,5-bis {2-hydroxyphenyl-5-[(2-sulfate-4-sulfatoethylsulphonyl-azobenzol) methylene amino]} benzoic acid. Metal ions, Co2+, Mn2+, and Cu2+, were anchored to the modified cellulose by controlling assembly. The cellulose-supported complexes were characterized and the catalytic activity for H2O2 was investigated. Elemental analyses of the cellulose supported complexes, MC–Co, MC–Mn, were well agreed with the proposed composition. Three cellulose-supported complexes had strong catalytic activities for H2O2. H2O2 decomposition rates in 10 min were 84.54% for MC–Co, 94.87%, for MC–Mn, and 77.21% for MC–Cu, respectively. The manganese complex had the strongest catalytic activity among them. The cellulose-supported complexes have potential application in wastewater treatment and biotechnology.

Magnetically Modulated Pot‐Like MnFe2O4 Micromotors: Nanoparticle Assembly Fabrication and their Capability for Direct Oil Removal

This work demonstrates a simple‐structured, low‐cost magnetically modulated micromotor of MnFe2O4 pot‐like hollow microparticles as well as its facile, versatile, and large‐scale growing‐bubble‐templated nanoparticle (NP) assembly fabrication approach. In this approach, the hydrophobic MnFe2O4@oleic acid NPs in an oil droplet of chloroform and hexane assembled into a dense NP shell layer due to the hydrophobic interactions between the NP surfaces. With the encapsulated oil continuously vaporizing into high‐pressured gas bubbles, the dense MnFe2O4 NP shell layer then bursts, forming an asymmetric pot‐like MnFe2O4 micromotor by creating a single hole in it. For the as‐developed simple pot‐like MnFe2O4 micromotor, the catalytically generated O2 molecules nucleate and grow into bubbles preferentially on the inner concave surface rather than on the outer convex surface, resulting in continuous ejection of O2 bubbles from the open hole to propel it. Dexterously integrating the high catalytic activity for H2O2 decomposition to produce O2 bubbles, excellent magnetic property with the instinctive surface hydrophobicity, the MnFe2O4 pot‐like micromotor not only can autonomously move in water media with both velocity and direction modulated by external magnetic field but also can directly serve for environmental oil removal without any further surface modification. The results here may inspire novel practical micromotors.

Electrochemiluminescence immunosensor based on multifunctional luminol-capped AuNPs@Fe3O4 nanocomposite for the detection of mucin-1.

In this work, a novel and multifunctional nanocomposite of luminol capped gold modified Fe3O4 (Lu-AuNPs@Fe3O4) was utilized as the carrier of secondary antibody (Ab2) to fabricate a sandwiched electrochemiluminescence (ECL) immunosensor for ultrasensitive detection of mucin-1 (MUC1). Herein, the luminol capped gold nanoparticles (Lu-AuNPs) were synthesized with HAuCl4 and luminol by the help of NaBH4 at room temperature, and then Lu-AuNPs were adsorbed on the Fe3O4 magnetic nanoparticles (MNPs) to form the nanocomposite of Lu-AuNPs@Fe3O4 via electrostatic interaction. Fe3O4 MNPs in Lu-AuNPs@Fe3O4 exhibited excellent conductivity and admirable catalytic activity in H2O2 decomposition, which could enhance the ECL efficiency of luminol-H2O2 system. In addition, the substrates of gold coated ZnO nanoparticles (AuNPs@ZnO), providing large specific surface areas for primary antibody (Ab1) capturing, were modified on the electrode. As a result, a wide linear range of 7 orders of magnitude from 10 fg/mL to 10 ng/mL was obtained with an ultralow detection limit of 4.5 fg/mL for MUC1.

Synthesis of novel Schiff base metal complexes with reactive groups and their catalytic property for hydrogen peroxide decomposition

A novel water soluble azo Schiff base ligand containing crosslinking reactive groups (A), 3,5-bis [(2-hydroxy-4′-sodiumsulphatoethylsulphonyl) azobenzene- methyneimino]-benzoic acid (BHSABA), and its complexes with Mn2+, Cu2+, Co2+, were synthesized and characterized by elemental analysis, Fourier transform infrared (FT-IR) and proton nuclear magnetic resonance (1HNMR) spectroscopy. The Schiff base ligand and its complexes had excellent water solubility. Two reactive groups, p-[(2′-sulphatoethyl) sulphonyl groups, were able to form covalent bonds with biomass, such as cellulose, chitosan and so on, to obtain functional material. Ultraviolet–visible (UV-vis) electronic absorbance and fluorescence spectra of the ligand having azo conjugated system and of the metal complexes were measured. The catalytic activity of the ligand and the complexes for H2O2 decomposition were also investigated. The results show that the fluorescence spectra of the complexes, Co2A and Mn2A, had increased fluorescence phenomena. They had strong catalytic activity for H2O2 decomposition. When the concentration of manganese complex, Mn2A, was 5 mg/l, H2O2 decomposition nearly finished in 40 min at 40℃. The order of catalytic activity of three complexes for H2O2 decomposition was Mn2A > Co2A > Cu2A. The ligand itself had no noticeable catalytic activity for H2O2 decomposition. These novel water soluble Schiff base metal complexes with reactive groups have potential application in the H2O2 decomposition of water treatment fields.

Surface chemical and photocatalytic consequences of Ca-doping of BiFeO3 as probed by XPS and H2O2 decomposition studies

Pure and Ca-doped Bi1−xCaxFeO3 samples were prepared with x=0.0–0.2, adopting a sol–gel method. Previously reported studies performed on similarly composed and prepared samples revealed that Ca-doping, above solubility limit (namely at ≥10%-Ca), results in phase separation and formation of BiFeO3/α(γ)-Fe2O3 nanocomposite particles. Hetero p/n nanojunctions thus established were considered to help separating photo-generated electron–hole pairs and, therefore, explain consequent promotion of photo-Fenton catalytic activity of BiFeO3 towards methylene blue degradation in presence of H2O2 additive. However, the encompassed decomposition of H2O2 was not addressed. To bridge this gap of knowledge, the present investigation was designed to assess Ca-doping-effected surface chemical modifications and gauge its impact on the heterogeneous photo-/thermo-catalytic activity of BiFeO3 towards H2O2 decomposition, by means of X-ray photoelectron spectroscopy (XPS) and H2O2 decomposition gravimetry. XPS results revealed generation of high binding energy Bi 4f and Fe 2p states, as well as enhancement of the surface basicity, upon doping to 10%-Ca. These surface chemical consequences are rendered hardly detectable upon further increase of the dopant magnitude to 20%-Ca. In parallel, the H2O2 decomposition activity of the ferrite, under natural visible light, is enhanced to optimize upon Ca-doping at 10%, and, then, decreased on further doping to 20%. H2O2 decomposition experiments carried out in absence of light indicate that the doping promoting impact is reflected essentially in the photocatalytic activity. Accordingly, the observed surface chemical consequences of Ca-doping are considered to consolidate the p/n nanojunctions consequently established in the material bulk, by retarding recombination of visible light generated electron–hole pairs, thus enhancing the heterogeneous photocatalytic activity of BiFeO3.

Highly stable iron catalysts from sewage sludge for CWPO

Abstract Sewage sludge was used as precursor to prepare catalysts for catalytic wet peroxide oxidation (CWPO) by both simple drying and pyrolysis. Iron-on-activated biosolids (Fe/ABS) catalysts were obtained from the dried biosolids, upon contact with aqueous solution of FeCl3 at different concentrations followed by thermal treatment at 750 °C for 30 min. The materials obtained showed a low developed porosity, corresponding essentially to narrow microporosity, with total iron contents up to 9.3% (w:w). The preparation procedure allowed a homogeneous distribution of the active phase, mainly on the external surface of the resulting materials, favoring the catalytic activity in aqueous phase. The catalysts showed a relatively high activity for H2O2 decomposition, as well as high oxidation efficiency with three target pollutants (phenol, bromophenol blue and dimethoate), allowing a high mineralization (65% TOC reduction in the cases of phenol and dimethoate). A fairly good stability was observed in long-term continuous experiments where the Fe leaching remained below 11% of the initial loading after 170 h on stream at a 2.0 kgcat h/molphenol space time.

Vermiculite-based catalyts for oxidation of organic pollutants in water and wastewater

In presented work natural expanded vermiculite was used as a starting material for synthesis of Fe-doped catalysts. Material was modified with increasing amount of Fe by ion-exchange and precipitation of iron oxide. Composite materials were characterized with respect to their structure (X-ray diffraction, Infrared spectra using Diffuse Reflectance), agglomeration state of Fe (Ultraviolet-Visible spectra using Diffuse Reflectance) and chemical composition. Activity in H2O2 decomposition as well as in phenol oxidation was studied in liquid phase at atmospheric pressure and temperature up to 70 °C. It was shown that doping with Fe increases catalytic activity. However, excess of iron resulted in formation of undesired side-products.

New highly ordered hydrophobic siloxane-based coordination polymers

Two H-bond polymers from carboxypropyl disubstituted disiloxane and bipyridyl compounds, as well as the starting components in different ratios were reacted with zinc acetate. Two new siloxane-containing coordination polymers were thus obtained and characterized. They exhibited highly ordered structures, which were investigated by single crystal XRD. One of the H-bond polymers, as well as a third coordination polymer, without the siloxane component (obtained as secondary product) were also structurally characterized. The siloxane coordination polymer obtained with 4,4′-bipyridyl has a 2D MOF structure. The homologous polymer derived from 1,2-(4-bipyridyl)ethylene forms undulated 2D-layers which are packed in the crystal leading to partial interpenetration with formation of two types of channels along crystallographic axis c. The new siloxane-containing coordination polymers were investigated by FT-IR, DSC–TG–TGA, DVS and static contact angle measurements. They are hydrophobic (by contact angle) and even superhydrophobic effect was observed on bulk powder for one of them. The solvent sorption capacity was measured by tensiometry. They were tested for catalytic activity in H2O2 decomposition and preliminary experiments for oxidation of glucose and viscose were done.

Vapour phase H2O2 decomposition on Mn based monolithic catalysts synthesized by innovative procedures

Manganese oxide catalysts supported on monolithic yttria stabilized zirconia honeycombs were studied for H2O2 decomposition in view of space propulsion applications. The materials were prepared by impregnation (IM), precipitation (PR) and sol–gel (SG) methods and characterized by N2 adsorption, SEM and H2 temperature programmed reduction (TPR). The catalytic activity for H2O2 decomposition was studied under vapour phase conditions. The tests were carried out in a flow apparatus at T=200°C, gas hourly space velocity (GHSV)=2.00 and 2.67s−1, H2O2 concentrations of 11.3mol%. The redox properties of the catalysts were markedly influenced by the preparation method. In the SG catalyst, a large fraction of Mn was not reducible in the TPR tests differently from the PR and IM materials. Despite this effect, the SG catalyst showed an activity comparable or higher than that of PR and IM, due to a more effective dispersion of Mn species. A too strong effect of space velocity on H2O2 conversion was attributed to an autocatalytic effect. A radical mechanism was hypothesized: it was assumed that a reaction between O2 and Mn species produced radicals that promoted the overall reaction.

Effect of calcination temperature on the H2O2 decomposition activity of nano-crystalline Co3O4 prepared by combustion method

Cobalt oxide nano-particles were prepared by combustion method using urea as a combustion fuel. The effects of calcination temperature, 350–1000°C, on the physicochemical, surface and catalytic properties of the prepared Co3O4 nano-particles were studied. The products were characterized by thermal analyses (TGA & DTA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. Textural features of the obtained catalysts were investigated using nitrogen adsorption at −196°C. X-ray diffraction confirmed that the resulting oxide was pure single-crystalline Co3O4 nano-particles. Transmission electron microscopy indicating that, the crystallite size of Co3O4 nano-crystals was in the range of 8–34nm. The catalytic activities of prepared nano-crystalline Co3O4 catalysts were tested for H2O2 decomposition at 35–50°C temperature range. Experimental results revealed that, the catalytic decomposition of H2O2 decreases with increasing the calcination temperature. This was correlated with the observed particle size increase accompanying the calcination temperature rise.

Near-infrared light controlled photocatalytic activity of carbon quantum dots for highly selective oxidation reaction

Selective oxidation of alcohols is a fundamental and significant transformation for the large-scale production of fine chemicals, UV and visible light driven photocatalytic systems for alcohol oxidation have been developed, however, the long wavelength near infrared (NIR) and infrared (IR) light have not yet fully utilized by the present photocatalytic systems. Herein, we reported carbon quantum dots (CQDs) can function as an effective near infrared (NIR) light driven photocatalyst for the selective oxidation of benzyl alcohol to benzaldehyde. Based on the NIR light driven photo-induced electron transfer property and its photocatalytic activity for H2O2 decomposition, this metal-free catalyst could realize the transformation from benzyl alcohol to benzaldehyde with high selectivity (100%) and conversion (92%) under NIR light irradiation. HO˙ is the main active oxygen specie in benzyl alcohol selective oxidative reaction confirmed by terephthalic acid photoluminescence probing assay (TA-PL), selecting toluene as the substrate. Such metal-free photocatalytic system also selectively converts other alcohol substrates to their corresponding aldehydes with high conversion, demonstrating a potential application of accessing traditional alcohol oxidation chemistry.

High-yield synthesis of ultrathin silica-based nanosheets and their superior catalytic activity in H2O2 decomposition

Ultrathin silica-based nanosheets with a thickness of ∼1 nm are fabricated in a low-cost and high-yield system excluding alkali metal ions. Unlike the Na-zeolites with a long capillary and microporous structure, the ultrathin nanosheets exhibit highly effective surface and active sites. As a result, the 0.4 wt% Pt-loaded nanosheets exhibit superior catalytic activity in H(2)O(2) decomposition with an O(2) evolution rate of 342.5 mL g(-1) min(-1) in a clean aqueous system.

Investigation of the solid state reaction of LaMnO3 with Feº and its effect on the catalytic reactions with H2O2

In this work, the reaction of the perovskite LaMnO3.15 with Feº has been promoted by thermal treatment of the mixture Feº/LaMnO3.15 at 200, 400 and 600 ºC. Mössbauer spectroscopy, X-ray diffraction (XRD), temperature programmed reduction (TPR) and temperature programmed desorption (O2-TPD) analyses suggested that at 400 and 600 ºC oxygen from perovskite is transferred to Feº to produce an oxygen deficient perovskite, LaMnO3-d, and highly dispersed iron oxides, mainly Fe3O4 and FeO. XRD lattice parameters and crystallite size showed that LaMnO3 suffers a strong lattice distortion after reaction but no collapse of the perovskite structure. Reactivity studies pointed to a special interface effect of Feº/LaMO3 towards two reactions with H2O2, the decomposition to O2 and the oxidation of the model molecule, the methylene blue dye. As the treatment temperature of the Feº/LaMnO3.15 increased, the activity for H2O2 decomposition decreased, whereas the activity for the dye oxidation increased. These results are discussed in terms of a decrease in the concentration of Mn4+surf and Mn3+surf species, active for the H2O2 decomposition, with the formation of Mn2+surf and Fe2+surf species, active for the Fenton reaction.

A sinusoidal chain constructed from decorated Keggin clusters and {Cu(enMe)2}2+ bridging groups in [Cu(enMe)2(H2O)] [{Cu(enMe)2}{Cu(enMe)2(H2O)W12O40(H2)}] · nH2O

A novel organic–inorganic hybrid material, [Cu(enMe)2(H2O)][{Cu(enMe)2}{Cu(enMe)2(H2O)W12O40(H2)}]·nH2O (n=0.33, enMe=1,2-diaminopropane), has been prepared under mild hydrothermal conditions and characterized by single-crystal X-ray diffraction, IR and magnetic susceptibility measurements. It is revealed that the one-dimensional [{Cu(enMe)2}{Cu(enMe)2(H2O)W12O40(H2)}]2− chain in the structure shows a unique sinusoidal ruffling, which is constructed from decorated Keggin clusters and {Cu(enMe)2}2+ bridging groups through sharing one terminal and one doubly-bridging oxygen atoms of a cluster. The magnetic measurements show that the compound possesses well-separated Cu2+ centers. It was indicated that the hybrid exhibits a good catalytic activity in H2O2 decomposition.

ZrIV-Monosubstituted Keggin-Type Dimeric Polyoxometalates: Synthesis, Characterization, Catalysis of H2O2-Based Oxidations, and Theoretical Study

The previously unknown Zr(IV)-monosubstituted Keggin-type polyoxometalates (Zr-POMs), (n-Bu4N)7H[{PW11O39Zr(mu-OH)}2] (1), (n-Bu4N)8[{PW11O39Zr(mu-OH)}2] (2), and (n-Bu4N)9[{PW11O39Zr}2(mu-OH)(mu-O)] (3) differing in their protonation state, have been prepared starting from heteropolyacid H5PW11ZrO40.14H2O. The compounds were characterized by elemental analysis, potentiometric titration, X-ray single-crystal structure, and IR, Raman, and 31P and 183W NMR spectroscopy. The single-crystal X-ray analysis of 2 reveals that two Keggin structural units [PW11O39Zr]3- are linked through two hydroxo bridges Zr-(OH)-Zr with Zr(IV) in 7-fold coordination. The IR spectra of 1 and 2 show a characteristic band at 772 cm(-1), which moves to 767 cm(-1) for 3, reflecting deprotonation of the Zr-(OH)-Zr bond. Potentiometric titration with methanolic Bu4NOH indicates that 1-3 contain 2, 1, and 0 acid protons, respectively. (83W NMR reveals Cs symmetry of 2 and 3 in dry MeCN, while for 1, it discovers nonequivalence of its two subunits and their distortion resulting from localization of the acidic proton on one of the Zr-O-W bridging O atoms. The (31)P NMR spectra of 2 and 3 differ insignificantly in dry MeCN, showing only signals at delta -12.46 and -12.44 ppm, respectively, while the spectrum of 1 displays two resonances at delta -12.3 (narrow) and -13.2 (broad) ppm, indicating slow proton exchange on the (31)P NMR time scale. The theoretical calculations carried out at the density functional theory level on the dimeric species 1-3 propose that protonation at the Zr-O-Zr bridging site is more favorable than protonation at Zr-O-W sites. Calculations also revealed that the doubly bridged hydroxo structure is thermodynamically more stable than the singly bridged oxo structure, in marked contrast with analogous Ti- and Nb-monosubstituted polyoxometalates. The interaction of 1-3 with H(2)O and H(2)O(2) in MeCN has been studied by both (31)P and (183)W NMR. The stability of the [PW(11)O(39)ZrOH](4-) structural unit toward at least 100-fold excess of H2O2 in MeCN was confirmed by both NMR and Raman spectroscopy. The interaction of 1 and 2 with H2O in MeCN produces most likely monomeric species (n-Bu4N)3+n[PW11O39Zr(OH)(n(H2O)(3-n)] (n = 0 and 1) showing a broad 31P NMR signal at delta -13.2 ppm, while interaction with H2O2 leads to the formation of an unstable peroxo species (delta -12.3 ppm), which reacts rapidly with cyclohexene, producing 2-cyclohexen-1-one and trans-cyclohexane-1,2-diol. Both 1 and 2 show a pronounced catalytic activity in H2O2 decomposition and H2O2-based oxidation of organic substrates, including cyclohexene, alpha-pinene, and 2,3,6-trimethylphenol. The oxidation products are consistent with those of a homolytic oxidation mechanism. On the contrary, 3 containing no acid protons reacts with neither H2O nor H2O2 and shows negligible catalytic activity. The Zr-monosubstituted polyoxometalates can be used as tractable homogeneous probes of Zr single-site heterogeneous catalysts in studying mechanisms of H2O2-based oxidations.

Drastic increase of selectivity for H2O2 formation in direct oxidation of H2 to H2O2 over supported Pd catalysts due to their bromination.

Incorporation of bromide anions (1.0 wt%) in supported Pd catalysts (viz. Pd supported on Al2O3, ZrO2, SiO2, H-beta or Ga2O3) leads to a drastic increase in their selectivity for H2O2 formation in the direct oxidation of H2 to H2O2 by O2(at room temperature) in an aqueous acidic (0.03 M H3PO4) reaction medium; the selectivity increase is accompanied by a large decrease in the H2O2 decomposition activity of the catalysts.

The Effect of Calcium Doping on the Surface and Catalytic Properties of Cobaltic Oxide Catalysts

The effects of calcium oxide doping (0.75, 1.5 and 3 mol% CaO) and calcination temperature (400, 500, 600 and 700°C) on different surface properties of Co3O4 were investigated. The structural properties of pure and doped oxide samples were determined by XRD methods, the textural properties were investigated via the adsorption of nitrogen at −196°C while the hydrogen peroxide decomposition activity of the investigated solids was determined by oxygen gasometric measurement of the reaction kinetics at 20–40°C. The dissolution of calcium ions in the Co3O4 lattice at temperatures in the range 400–600°C was accompanied by a marked decrease in the mean hydraulic radii (rh) and an increase in the surface area (SBET) and total pore volume (Vp) of the prepared oxide samples. In contrast, doping at 700°C brought about a decrease in the SBET and Vp values of the investigated solids. The catalytic activity for H2O2 decomposition on cobaltic oxide calcined at 400–700°C was found to decrease considerably on doping with CaO. The activation energy for sintering (ΔEs) of the pure and doped solids was determined from the variation in their SBET values as a function of the calcination temperature of these solids. Calcium oxide treatment resulted in a 50% increase in the activation energy of sintering of cobaltic oxide solid calcined at 400–600°C. This increase reflects the role of CaO doping in hindering the sintering of cobaltic oxide.

Effect of gamma-irradiation on surface and catalytic properties of Co3O4 doped with NiO

NiO-doped Co3O4 samples precalcined at 500 °C were subjected to various doses of γ-rays within the range 0.2-1.6 MGy. The particle size and BET-surface areas of different samples were determined using XRD and nitrogen adsorption at -196 °C. The catalytic reactions studied were conversion of ethanol and isopropanol at 250-400 °C using a micropulse technique and H2O2 decomposition in aqueous solution at 30-50 °C. The results revealed that the γ-irradiation brought a significant decrease in the particle size of Co3O4 phase with subsequent increase in the SBET surface areas. The treatment brought also a progressive decrease in the total conversion of both alcohol (dehydration and dehydrogenation) falling to a minimum value (about 20% of its initial activity) at a dose of 0.8 MGy. The catalysts retain their initial activity upon exposure to a dose of 1.6 MGy. On the other hand, the catalytic activity in H2O2 decomposition of the investigated system decreased progressively by increasing the dose of γ-rays and the catalysts lost more than 90% of their initial activity upon exposure to a dose of 1.6 MGy.

Effects of ZrO2-doping of a CuO/MgO system on its surface and catalytic properties

The effects of doping of CuO/MgO system with ZrO2 (3/10 wt.%) on its surface and catalytic properties were investigated. Pure and differently doped solids were subjected to heat treatment at 400 and 700 8C. The formula of the undoped calcined solids was 0.2 CuO/MgO. The results revealed that ZrO2-doping increased the degree of dispersion for CuO phase. The specific surface area of the system investigated decreased to an extent proportional to the amount of zirconia added. The catalytic activity in H2O2 decomposition of the investigated solids increased by increasing the amount of ZrO2 added. The maximum increase in the catalytic activity expressed as the reaction rate constant per unit surface area k was calculated for the reaction conducted at 20 8C (k 20 C ) /due to doping with 10 wt.% ZrO2 followed by calcination at 400 and 700 8C are 703 and 617%, respectively. The doping process did not modify the activation energy of the catalyzed reaction but rather increased the concentration of the active sites without changing their energetic nature. # 2002 Elsevier Science B.V. All rights reserved.