Performance and characterization of Ru/Al2O3 and Ru/SiO2 catalysts modified with Mn for Fischer–Tropsch synthesis

Mn effect and characterization on γ-Al₂O₃-, -Al₂O₃- and SiO₂-supported Ru catalysts were investigated for Fischer–Tropsch synthesis under pressurized conditions. In the slurry phase Fischer–Tropsch reaction, γ-Al₂O₃ catalysts showed higher performance on CO conversion and C₅⁺ selectivity than -Al₂O₃ and SiO₂ catalysts. Moreover, Ru/Mn/γ-Al₂O₃ exhibited high resistance to catalyst deactivation and other catalysts were deactivated during the reaction. From characterization results on XRD, TPR, TEM, XPS and pore distribution, Ru particles were clearly observed over the catalysts, and γ-Al₂O₃ catalysts showed a moderate pore and particle size such as 8 nm, where -Al₂O₃ and SiO₂ showed highly dispersed ruthenium particles. The addition of Mn to γ-Al₂O₃ enhanced the removal of chloride from RuCl₃, which can lead to the formation of metallic Ru with moderate particle size, which would be an active site for Fischer–Tropsch reaction. Concomitantly, manganese chloride is formed. These schemes can be assigned to the stable nature of Ru/Mn/γ-Al₂O₃ catalyst.     

Fischer–Tropsch synthesis on monolithic catalysts with oil circulation

Monolithic catalysts made of cordierite and γ-Al₂O₃ have been prepared and tested for the Fischer–Tropsch (FT) synthesis. When operated without oil circulation, washcoated cordierite monoliths have previously been shown to be as active and selective as the corresponding powder catalyst provided that the monoliths have low washcoat loadings. Two-phase operation, i.e. with oil/product circulation during reaction, resulted in improved heat removal and temperature control, in lower apparent activity and faster deactivation, but the C₅₊ selectivity was equal to or even better than without oil circulation. The lower apparent activities obtained with oil circulation seem to be a combination of catalyst deactivation and flow-related problems in the present experimental set-up.     

Fischer–Tropsch synthesis using monolithic catalysts

Square channel cordierite monoliths have been loaded with alumina washcoat layers of various thicknesses (20–110 μm) and loaded with rhenium and cobalt resulting in a 0.1 wt.% Re/17 wt.% Co/Al₂O₃ catalyst. These monolithic catalysts have been tested in the Fischer–Tropsch synthesis in a temperature window (180–225 °C) under synthesis gas compositions ranging from stoichiometrically excess carbon monoxide to excess hydrogen (H₂/CO = 1–3). The results include data on the activity and selectivity of CoRe/Al₂O₃ monolithic catalysts for FTS under these process conditions. Washcoat layers thicker than about 50 μm appear to lead to internal diffusion limitations. Thinner washcoat layers yield, depending on the conditions, to larger amounts of -olefins than alkanes for chain lengths below 10 carbon atoms. ASF and non-ASF chain length distributions are obtained for thin washcoats, whereby the chain growth probability increases from 0.83 to 0.93. Under certain conditions the amounts of alkanes even increase with chain length. These experimental results with different diffusion lengths have been used to analyze the effects of secondary reactions on FTS selectivity.     

Surface properties and reactivity of Cu/γ-Al2O3 catalysts for NO reduction by C3H6: Influences of calcination temperatures and additives

The influences of calcination temperatures and additives for 10 wt.% Cu/γ-Al₂O₃ catalysts on the surface properties and reactivity for NO reduction by C₃H₆ in the presence of excess oxygen were investigated. The results of XRD and XPS show that the 10 wt.% Cu/γ-Al₂O₃ catalysts calcined below 973 K possess highly dispersed surface and bulk CuO phases. The 10 wt.% Cu/γ-Al₂O₃ and 10 wt.% Mn–10 wt.% Cu/γ-Al₂O₃ catalysts calcined at 1073 K possess a CuAl₂O₄ phase with a spinel-type structure. In addition, the 10 wt.% La–10 wt.% Cu/γ-Al₂O₃ catalyst calcined at 1073 K possesses a bulk CuO phase. The result of NO reduction by C₃H₆ shows that the CuAl₂O₄ is a more active phase than the highly dispersed and bulk CuO phase. However, the 10 wt.% Mn–10 wt.% Cu/γ-Al₂O₃ catalyst calcined at 1073 K possesses significantly lower reactivity for NO reduction than the 10 wt.% Cu/γ-Al₂O₃ catalyst calcined at 1073 K, although these catalysts possess the same CuAl₂O₄ phase. The low reactivity for NO reduction for 10 wt.% Mn–10 wt.% Cu/γ-Al₂O₃ catalyst calcined at 1073 K is attributed to the formation of less active CuAl₂O₄ phase with high aggregation and preferential promotion of C₃H₆ combustion to CO_x by MnO₂. The engine dynamometer test for NO reduction shows that the C₃H₆ is a more effective reducing agent for NO reduction than the C₂H₅OH. The maximum reactivity for NO reduction by C₃H₆ is reached when the NO/C₃H₆ ratio is one.     

Co from partial reduction of La(Co,Fe)O3 perovskites for Fischer–Tropsch synthesis

Small Co clusters (d<10 nm) supported over mixed La–Co–Fe perovskites were successfully synthesized. These catalysts were active for Fischer–Tropsch (FT). Depending on the Co to Fe ratios the mixed perovskite exhibited two different forms: the rhombohedral phase of LaCoO₃ is maintained for the mixed perovskite when x>0.5, the orthorhombic phase of LaFeO₃ is found for x<0.5. Interestingly only one of these structures is active for the FT reaction: the orthorhombic structure. This is most likely due to the capacity of this material to maintain its structure even with a high number of cation vacancies. These cations (mostly Co) were on purpose extracted and reduced. Magnetic measurements clearly showed their metallic nature. Rhombohedral Co–Fe mixed perovskites (x≥0.5) cannot be used as precursors for Fischer–Tropsch catalysts: their partial reduction only consists in a complete reduction of Co³⁺ into Co²⁺.

The partial reduction of orthorhombic perovskites (x<0.5) leads to active Fischer–Tropsch (FT) catalysts by formation of a metal phase well dispersed on a cation-deficient perovskite. The FT activity is related to the stability of the precursor perovskite. When initially calcined at 600 °C, a maximum of 8.6 wt.% of Co⁰ can be extracted from LaCo_0.40Fe_0.60O₃ (compared to only 2 wt.% after calcination at 750 °C). The catalyst is then composed of Co⁰ particles of 10 nm on a stable deficient perovskite LaCo_0.05³⁺Fe_0.60³⁺O_2.40. Catalytic tests showed that up to 70% in the molar selectivity for hydrocarbons was obtained at 250 °C, 40% of which was composed of the C₂–C₄ fraction.     

Effect of phosphorus addition on the hydrotreating activity of NiMo/Al2O3 carbide catalyst

A series of phosphorus promoted γ-Al₂O₃ supported NiMo carbide catalysts with 0–4.5 wt.% P, 13 wt.% Mo and 2.5 wt.% Ni were synthesized and characterized by elemental analysis, pulsed CO chemisorption, BET surface area measurement, X-ray diffraction, near-edge X-ray absorption fine structure, DRIFT spectroscopy of CO adsorption and H₂ temperature programmed reduction. X-ray diffraction patterns and CO uptake showed the P addition to NiMo/γ-Al₂O₃ carbide, increased the dispersion of β-Mo₂C particles. DRIFT spectra of adsorbed CO revealed that P addition to NiMo/γ-Al₂O₃ carbide catalyst not only increases the dispersion of Ni-Mo carbide phase, but also changes the nature of surface active sites. The hydrodenitrogenation (HDN) and hydrodesulfurization (HDS) activities of these P promoted NiMo/γ-Al₂O₃ carbide catalysts were performed in trickle bed reactor using light gas oil (LGO) derived from Athabasca bitumen and model feed containing quinoline and dibenzothiophene at industrial conditions. The P added NiMo/γ-Al₂O₃ carbide catalysts showed enhanced HDN activity compared to the NiMo/γ-Al₂O₃ catalysts with both the feed stocks. The P had almost no influence on the HDS activity of NiMo/γ-Al₂O₃ carbide with LGO and dibenzothiophene. P addition to NiMo/γ-Al₂O₃ carbide accelerated CN bond breaking and thus increased the HDN activity.     

Novel utilization of MCM-22 molecular sieves as supports of cobalt catalysts in the Fischer–Tropsch synthesis

Cobalt catalysts (2–10 wt% Co) supported on silica-rich MCM-22 zeolites have been prepared by impregnation with aqueous Co(NO₃)₂ solutions. The catalysts are characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), nitrogen adsorption, solid state nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The catalytic properties for the Fischer–Tropsch synthesis (FTS) at 280 °C, 12.5 bar and H₂/CO = 2 are evaluated. The catalysts supported on MCM-22 exhibit the highest selectivity to long-chain (C₅₊) hydrocarbons when MCM-22 supports are synthesized with the appropriate Si/Al ratio.     

Fischer–Tropsch synthesis over Re-promoted Co supported on Al2O3, SiO2 and TiO2: Effect of water

The activity and selectivity of rhenium promoted cobalt Fischer–Tropsch catalysts supported on Al₂O₃, TiO₂ and SiO₂ have been studied in a fixed-bed reactor at 483 K and 20 bar. Exposure of the catalysts to water added to the feed deactivates the Al₂O₃ supported catalyst, while the activity of the TiO₂ and SiO₂ supported catalysts increased. However, at high concentrations of water both the SiO₂ and TiO₂ supported catalyst deactivated. Common for all catalysts was an increase in C₅₊ selectivity and a decrease in the CH₄ selectivity by increasing the water partial pressure. The catalysts have been characterized by scanning transmission electron microscope (STEM), BET, H₂ chemisorption and X-ray diffraction (XRD).     

Palladium–vanadium interaction in binary supported catalysts

We have studied the activity and selectivity of Pd/γ-Al₂O₃, VO_x/γ-Al₂O₃ and Pd–VO_x/γ-Al₂O₃ catalysts for the decomposition of NO and the reduction of NO with CO. Pd–VO_x/γ-Al₂O₃ catalysts were prepared by anchoring Pd(AcAc)₂ on VO_x/γ-Al₂O₃. Characterization of the binary samples by hydrogen chemisorption and TPR measurements indicated that the reduction of VO_x is enhanced by a close contact with palladium and that partially reduced vanadia decorate noble metal particles. This palladium–vanadium interaction alters the catalytic properties of palladium: the activity for NO decomposition is higher for the binary sample and, for the NO–CO reaction, both the activity and the selectivity to N₂ increase when vanadium is in contact with palladium.     

Supercritical phase process for direct synthesis of middle iso-paraffins from modified Fischer–Tropsch reaction

A new concept on the direct synthesis of middle iso-paraffins through the modified supercritical Fischer–Tropsch (FT) reaction was proposed and experimentally demonstrated with the combination of Co/SiO₂ and palladium-supported β zeolite (Pd/β) catalysts both in one-stage and two-stage fixed-bed reaction systems. Depending on the reaction conditions, the selectivity of C₄⁺ iso-paraffins mostly in gasoline range was 60–80% due to hydrocracking and hydro-isomerization function of Pd/β. Irrespective of reaction conditions, the hydrocarbons produced from FT reaction were preferentially hydro-converted over Pd/β catalyst while the supercritical solvent of n-hexane could only be slightly hydro-converted under severe conditions. The production of iso-paraffin in two-stage process was tested for 100 h without observable deactivation by feeding additional hydrogen in lower reactor, which is ascribed to the inhibition of coke deposition over Pd/β as revealed from TG analysis of the used catalysts.     

Dehydroisomerisation of n-butane over (Pt,Cu)/H-TON catalysts

Direct formation of isobutene from n-butane was investigated over zeolite TON and γ-Al₂O₃ supported platinum and platinum–copper catalysts. Addition of Cu decreases Pt dispersion, irrespective of preparation methods and nature of catalyst supports. The presence of potassium was found to reduce acidity and Pt dispersion. The experiments were performed in a fixed-bed microreactor system operating at 673 K and atmospheric pressure. Changing the support from γ-Al₂O₃ to TON, shows that n-butane conversion is almost independent of acidity. However, significant changes in products selectivities are observed. The selectivities to isobutene, C₁–C₃ fractions, and aromatics increases drastically from 3.5 to 32.6%, 20.3 to 27.2%, and 3.0 to 20.6%, respectively, for the TON-supported catalyst whereas dehydrogenation is largely predominant when γ-Al₂O₃ is used as support. Addition of Cu, as expected, has an adverse effect on n-butane conversion as less active sites are available due to the reduction in Pt dispersion. Though Cu addition has marginal effect on isobutene selectivity, it certainly suppresses hydrogenolysis which evidences a reduction in size of the Pt ensembles at the surface of the Pt particles.     

Effect of Re loading on the structure, activity and selectivity of Re/C catalysts in hydrodenitrogenation and hydrodesulphurisation of gas oil

A series of Re-containing catalysts supported on activated carbon, with Re loading between 0.74 and 11.44 wt.% Re₂O₇, was prepared by wet impregnation and tested in the simultaneous hydrodesulphurisation (HDS) and hydrodenitrogenation (HDN) of a commercial gas oil. Textural analysis, XRD, X-ray photoelectron spectroscopy (XPS) and surface acidity techniques were used for physicochemical characterisation of the catalysts. Increase in the Re concentration resulted in a rise in the HDS and HDN activity due to the formation of a monolayer structure of Re and the higher surface acidity. At Re concentrations >2.47 wt.% Re₂O₇ (0.076 Re atoms nm⁻²) the reduction in the catalytic activity was related to the loss in specific surface area (BET) due to reduction in the microporosity of the carbon support. The magnitude of the catalytic effect was different for HDS and HDN, and depended strongly on the Re content and reaction temperature. The apparent activation energies were about 116–156 kJ mol⁻¹ for HDS and 24–30 kJ mol⁻¹ for HDN. This led to a marked increase in the HDN/HDS selectivity with decreasing temperature (values >3 at 325 °C), due to the large differences in the apparent activation energies of HDS and HDN found for all catalysts. A gradual increase in the HDN/HDS selectivity with increased Re loading was also found and related to the observed increase of catalyst acidity. The results are compared with those obtained for a series of Re/γ-Al₂O₃ catalysts.     

Catalytic reduction of SO2 over supported transition-metal oxide catalysts with C2H4 as a reducing agent

This work investigates performances of supported transition-metal oxide catalysts for the catalytic reduction of SO₂ with C₂H₄ as a reducing agent. Experimental results indicate that the active species, the support, the feed ratio of C₂H₄/SO₂, and pretreatment are all important factors affecting catalyst activity. Fe₂O₃/γ-Al₂O₃ was found to be the most active catalyst among six γ-Al₂O₃-supported metal oxide catalysts tested. With Fe₂O₃ as the active species, of the supports tested, CeO₂ is the most suitable one. Using this Fe₂O₃/CeO₂ catalyst, we found that the optimal Fe content is 10 wt.%, the optimal feed ratio of C₂H₄/SO₂ is 1:1, and the catalyst presulfidized by H₂+H₂S exhibits a higher performance than those pretreated with H₂ or He. Although the feed concentrations of C₂H₄:SO₂ being 3000:3000 ppm provide a higher conversion of SO₂, the sulfur yield decreases drastically at temperatures above 300 °C. With higher feed concentrations, maximum yield appears at higher temperatures. The C₂H₄ temperature-programmed desorption (C₂H₄-TPD) and SO₂-TPD desorption patterns illustrate that Fe₂O₃/CeO₂ can adsorb and desorb C₂H₄ and SO₂ more easily than can Fe₂O₃/γ-Al₂O₃. Moreover, the SO₂-TPD patterns further show that Fe₂O₃/γ-Al₂O₃ is more seriously inhibited by SO₂. These findings may properly explain why Fe₂O₃/CeO₂ has a higher activity for the reduction of SO₂.     

High temperature calcined K–MoO3/γ-Al2O3 catalysts for mixed alcohols synthesis from syngas: Effects of Mo loadings

One series of oxidized K–MoO₃/γ-Al₂O₃ samples with different Mo loadings (MoO₃/Al₂O₃ (wt ratio)=0.05–0.45) was prepared by impregnating K and Mo compounds and successive calcination in air at 800°C. The oxidized samples were sulfided and then utilized for mixed alcohols synthesis from syngas. The structural information from laser Raman spectroscopy (LRS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ammonia saturation, temperature programmed desorption (TPD) and ethanol decomposition were studied to elucidate the reaction properties.

The results indicated that with Mo loading increased from MoO₃/Al₂O₃=0.05 to 0.25, the total yields of mixed alcohols and hydrocarbons decreased, but the selectivity to mixed alcohols was enhanced sharply from 3% to 50%. With Mo loading increased from MoO₃/Al₂O₃=0.25 to 0.45, the CO conversion was enhanced, but the selectivity to mixed alcohols leveled off. On these catalysts, Fischer–Tropsch (FT) synthesis to linear alcohols and the condensation reaction of low alcohols to form branched i-C₄OH occurred at the same time. With increased Mo loading, activity of the alcohols condensation became high.

Structural studies demonstrated that on oxidized samples with increased Mo loading the same K–Mo–O species was formed, but the dispersion of these K–Mo species decreased. The catalyst's acidity decreased remarkably with Mo loading up to MoO₃/Al₂O₃=0.25, and stayed unchanged as Mo loading was further increased to MoO₃/Al₂O₃=0.45. With increased Mo loading, the activity for ethanol dehydration changed parallel to the acidity. Results of the activity experiments for mixed alcohols' synthesis and the structural measurements indicated that the dispersion state of Mo species and the content of unreduced Mo species influenced the total CO conversion, and that the acidity of the catalyst controlled the selectivity to mixed alcohols.     

Preparation of new solid superacid catalyst, zirconium sulfate supported on γ-alumina and activity for acid catalysis

Zirconium sulfate supported on γ-Al₂O₃ catalysts were prepared by impregnation of powdered γ-Al₂O₃ with zirconium sulfate aqueous solution followed by calcining in air at high temperature. For Zr(SO₄)₂/γ-Al₂O₃ samples, no diffraction line of zirconium sulfate was observed up to 50 wt.%, indicating good dispersion of Zr(SO₄)₂ on the surface of γ-Al₂O₃. The acidity of catalysts increased in proportion to the zirconium sulfate content up to 40 wt.% of Zr(SO₄)₂. 40-Zr(SO₄)₂/γ-Al₂O₃ calcined at 400 °C exhibited maximum catalytic activities for 2-propanol dehydration and cumene dealkylation. The catalytic activities for both reactions, 2-propanol dehydration and cumene dealkylation were correlated with the acidity of catalysts measured by ammonia chemisorption method.     

Solid catalysts for wet oxidation of nitrogen-containing organic compounds

Several solid catalysts (Co₃O₄/γ-Al₂O₃, Fe₂O₃/γ-Al₂O₃, Mn₂O₃/γ-Al₂O₃, Zn–Fe–Mn–Al–O, Pt/γ-Al₂O₃, Ru/CeO₂, Ru/C) have been prepared and used to remove N-containing organic contaminants while processing toxic and hazardous industrial waste waters using wet oxidation by air (WAO). The autoclave tests of catalysts were done to reveal the main advantages of catalysts in water presence at high pressures and temperatures. Catalyst activity was determined with regard to oxygen interaction with model mixtures (water–organic contaminant: acetonitrile, carbamide, dimethyl formamide, or multi-component mixture of aliphatic alcohols). Activity tests were done in a static reactor under ideal mixing regime. Reagents and products were monitored using gas chromatograph Cvet-560, Millichrom-1 HPLC, and routine chemical analysis. Optimum process conditions for the best catalyst (Ru/graphite-like carbon) are as follows: partial oxygen pressure – 1.0 MPa, temperature – 473–513 K. At 0.5–5.0 MPa total pressure and 433–523 K catalysts show high water-resistance and high activity level (residual content of toxic compounds is less than 1%, and no NO_x and NH₃ are detected). There are no legal restrictions on catalysts operation, since they are harmless to environment.     

Fischer–Tropsch synthesis over Co–SiO2 catalysts prepared by the sol–gel method

Fischer–Tropsch synthesis was carried out in slurry phase over uniformly dispersed Co–SiO₂ catalysts prepared by the sol–gel method. When 0.01–1 wt.% of noble metals were added to the Co–SiO₂ catalysts, a high and stable catalytic activity was obtained over 60 h of the reaction at 503 K and 1 MPa. The addition of noble metals increased the reducibility of surface Co on the catalysts, without changing the particle size of Co metal significantly. High dispersion of metallic Co species stabilized on SiO₂ was responsible for stable activity. The uniform pore size of the catalysts was enlarged by varying the preparation conditions and by adding organic compounds such as N,N-dimethylformamide and formamide. Increased pore size resulted in decrease in CO conversion and selectivity for CO₂, a byproduct, and an increase in the olefin/paraffin ratio of the products. By modifying the surface of wide pore silica with Co–SiO₂ prepared by the sol–gel method, a bimodal pore structured catalyst was prepared. The bimodal catalyst showed high catalytic performance with reducing the amount of the expensive sol–gel Co–SiO₂.     

Ethylene epoxidation on Ag catalysts supported on non-porous, microporous and mesoporous silicates

The ethylene epoxidation activity of Ag catalysts supported on non-porous SiO₂, microporous silicalite zeolite and mesoporous MCM-41 and HMS silicates was investigated in the present study in comparison to conventional low surface area -Al₂O₃ based catalysts. The MCM-41 and HMS based catalysts exhibited similar ethylene conversion activity and ethylene oxide (EO) selectivity with the SiO₂ and -Al₂O₃ based catalysts at relatively lower temperatures (up to 230 °C), whereas their activity and selectivity decreased significantly at higher temperatures (≥300 °C). The silicalite based catalyst was highly active for a wide temperature range, similar to the SiO₂ and -Al₂O₃ based catalysts, but it was the less selective amongst all catalysts tested. High loadings of Ag particles (up to ca. 40 wt.%) with medium crystallites size (20–55 nm) could be achieved on the mesoporous materials resulting in very active epoxidation catalysts. The HMS-type silicate with the 3D network of wormhole-like framework mesopores (with average diameter of 3.5 nm), in combination with a high-textural (interparticle) porosity, appeared to be the most promising mesoporous support.     

Mechanistic differences in the selective reduction of NO by propene over cobalt- and silver-promoted alumina catalysts: kinetic and in situ DRIFTS study

The distribution of gaseous products and the nature of the surface species generated during the selective catalytic reduction of NO with C₃H₆ in the presence of excess O₂ (i.e. C₃H₆-SCR) were studied over both a 0.4% Co/γ-Al₂O₃ catalyst and a sulphated 1.2% Ag/γ-Al₂O₃ catalyst. The results were compared with those previously reported for the C₃H₆-SCR over 1.2% Ag/γ-Al₂O₃ and γ-Al₂O₃. High concentrations of NO₂ were observed in the product stream of the SCR reaction over the 0.4% Co/γ-Al₂O₃ and sulphated 1.2% Ag/γ-Al₂O₃ materials. The results show that (as in the case of the γ-Al₂O₃ and also probably that of the 1.2% Ag/γ-Al₂O₃) the NO₂ was formed via an alternative route to the direct oxidation of NO with O₂. The yields of NO₂ were higher over the Co/γ-Al₂O₃ than over the other materials and in contrast to the other materials, no NH₃ was produced over the Co/γ-Al₂O₃ catalyst. Based on these results and those of in situ DRIFTS experiments, a global reaction scheme incorporating organo-nitrogen species as key intermediates is proposed. In this scheme, NO, propene and oxygen react to form organo-nitro and/or organo-nitrito adsorbed species, the reaction products of which combine to yield N₂. The results reported here suggest that Co preferentially promotes the formation of nitrito-compounds which can readily decompose to NO₂, whereas Ag preferentially promotes the formation of nitro-compounds (from reaction of strongly bound ad-NO_x species) which can decompose to isocyanates and ammonia. The sulphation of the 1.2% Ag/γ-Al₂O₃ reduced the surface concentration of strongly bound ad-NO_x species which were thought to react with the reductant or derived species to yield the organo-nitrogen species.     

Preparation and structural characterization of Co/Al2O3 catalysts for the ozonation of pyruvic acid

A series of Co/Al₂O₃ catalysts were prepared by the incipient wetness impregnation method using γ-Al₂O₃ support and (CH₃COO)₂Co·4H₂O solutions, followed by calcination at 500–800 °C. Characterization of catalysts was accomplished by several techniques such as thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), physisorption of nitrogen, mercury and helium-based pycnometries, Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and pH of zero charge (PZC). Impregnation of support produced a moderate decrease of its surface area and pore volume and also led to minor changes of its PZC. Depending on preparation conditions (i.e., calcination atmosphere and temperature and metal loading), one or more of the following Co-containing compounds were identified: CoO, Co₃O₄ and CoAl₂O₄. The support and prepared Co/Al₂O₃ catalysts were tested to catalyze the ozonation of aqueous pyruvic acid at pH 2.5. Pyruvic acid was shown refractory towards single ozonation but the use of γ-Al₂O₃ and Co/Al₂O₃ catalysts resulted in 56–96% pyruvic acid conversion and 41–78% decrease in DOC after 2 h of ozonation of phosphate-buffered solutions. In the absence of the buffer, conversion rate was enhanced likely as a result of pH increase during the course of the process thus giving rise to the indirect way of ozonation through hydroxyl radicals. Acetic acid was found as the main by-product of pyruvic acid ozonation. Depending on the catalyst used, yield of acetic acid varied from 32 to 49%, values noticeably lower that that obtained from the control non-catalytic ozonation experiment (73%). Differences in catalytic activity amongst the various Co/Al₂O₃ catalysts investigated were attributed to the different Co active phases deposited on the γ-Al₂O₃ surface. The following sequence of increasing activity can be inferred from experimental results: CoO, CoAl₂O₄ and Co₃O₄. All the Co/Al₂O₃ catalysts prepared showed good stability as the percentage of cobalt leached out was rather low.