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Applied Catalysis B, Environmental (v.66, #3-4)

Contents Continued (pp. vi).

EDITORIAL BOARD (pp. co2).

FULL TITLE (pp. i).

Contents Volume 66 (pp. iii-iv).

Calendar of Forthcoming Events (pp. v).

Liquid phase catalytic hydrodechlorination of aryl chlorides over Pd–Al-MCM-41 catalyst by Tomonori Kawabata; Ikuo Atake; Yoshihiko Ohishi; Tetsuya Shishido; Yan Tian; Ken Takaki; Katsuomi Takehira (pp. 151-160).

Supported Pd catalysts were prepared by direct hydrothermal (DHT) or template-ion exchange (TIE) method on Al-substituted MCM-41 as the support and tested in the hydrodechlorination of aryl chlorides such as 4-chloroanisole in liquid phase, together with impregnated Pd catalysts as references. When Pd was loaded on Al-MCM-41 with the Si/Al ratio of 150 by the TIE method, the catalyst showed the highest activity among the Pd catalysts prepared. PdO originally formed on the catalyst surface was in situ reduced to Pd metal during the reaction as the active form for the dechlorination. The activities of the supported Pd catalysts well correlated with the Pd dispersion on the TIE or impregnated Pd catalysts, whereas the DHT catalysts showed relatively high activities independently on the Pd dispersions. It was confirmed that the dechlorination proceeded by a heterogeneous mechanism catalyzed by Pd metal particles sized less than 10nm on the surface of the catalyst. Al substitution for Si on MCM-41 was effective for the loading of Pd metal with the high dispersion, none the less Pd was located on the surface of the TIE catalyst particles and no significant effect of mesoporous structure on the reaction was observed. Methanol was the most profitable as the solvent among the various solvents tested. Various types of arylchlorides bearing hydroxy, methoxy, methyl, nitro and phenylcarbonyl group at the p-position were efficiently dechlorinated over Pd–Al-MCM-41 catalyst at 40°C. Electrophilic attack of arylchloride was proposed as the rate determining step, where ionic mechanism positively worked and electron-releasing substituents increased the catalytic activity.

Keywords: Catalytic hydrodechlorination; Aryl chlorides; 4-Chloroanisole; Pd catalyst; Al-MCM-41

Tungstated zirconia as promising carrier for DeNO_X catalysts with improved resistance towards alkali poisoning by Johannes Due-Hansen; Arkady L. Kustov; Søren Birk Rasmussen; Rasmus Fehrmann; Claus H. Christensen (pp. 161-167).

Use of biomass as an alternative to fossil fuels has achieved increasing interest since it is considered neutral regarding CO₂ accumulation in the atmosphere. The by far most energy-efficient use of solid bio-resources in energy production is combustion in combined biomass and coal or oil-fired power plants. However, in this operation traditional catalysts exhibit significant deactivation within relatively short time. The main reason for this deactivation is the presence of a high amount of potassium compounds, which act as poisons for the catalyst. Therefore, there is a need for development of new alternative catalysts that are more resistant towards poisoning with potassium.Vanadia-based catalysts supported on traditional and tungstated zirconia has been prepared and tested in selective catalytic reduction of NO with ammonia. All prepared catalysts were characterized using N₂-BET, XRD, and NH₃-TPD methods. The influence of calcination temperature of zirconia modified with tungsten oxide on the textural characteristics, acidity and catalytic performance was studied. The resistance of the catalysts towards model poisoning with potassium was found to depend dramatically on the crystallinity of the zirconia and on the surface acidity. Vanadia supported on tungstated zirconia calcined at 700°C revealed superior catalytic performance and resistance towards alkali poisoning in comparison with a traditional catalyst. The improved poisoning resistance of the samples based on tungstated zirconia can be related to the fact that a significant part of potassium on the surface of the catalyst preferentially interact with strong acidic sites now present on the support, thereby preventing vanadium species from poisoning and leaving them available for the catalytic cycle.

Keywords: Biomass; NO SCR with ammonia; Potassium poisoning; Deactivation; Tungstated zirconia; Vanadium oxide; NH; ₃; -TPD

In situ combustion synthesis of structured Cu-Ce-O and Cu-Mn-O catalysts for the production and purification of hydrogen by Joan Papavasiliou; George Avgouropoulos; Theophilos Ioannides (pp. 168-174).

The combustion method was employed for the in situ synthesis of nanocrystalline Cu-Ce-O and Cu-Mn-O catalyst layers on Al metal foam, without the need of binder or additional calcination steps. Copper-manganese spinel oxides have been proposed as a catalytic system for hydrogen production via methanol steam reforming, while CuO-CeO₂ catalysts have been successfully examined for CO removal from reformed fuels via selective oxidation. In this work, the performance of these catalysts supported on Al metal foam has been investigated in the reactions of methanol reforming and selective CO oxidation. The Cu-Ce-O foam catalyst exhibited similar catalytic performance to the one of the powder catalyst in the selective oxidation of CO. The performance of the Cu-Mn-O foam catalyst in the steam reforming of methanol was inferior to the one of the powder catalyst at intermediate conversion levels, but almost complete conversion of methanol was obtained at the same temperature with both foam and powder catalysts.

Keywords: Metal foam; Combustion synthesis; Copper; Cerium; Manganese; Hydrogen; Methanol; Reforming; PROX

Catalytic combustion of methane over bimetallic Pd–Pt catalysts: The influence of support materials by K. Persson; A. Ersson; S. Colussi; A. Trovarelli; S.G. Järås (pp. 175-185).

The effect of support material on the catalytic performance for methane combustion has been studied for bimetallic palladium–platinum catalysts and compared with a monometallic palladium catalyst on alumina. The catalytic activities of the various catalysts were measured in a tubular reactor, in which both the activity and stability of methane conversion were monitored. In addition, all catalysts were analysed by temperature-programmed oxidation and in situ XRD operating at high temperatures in order to study the oxidation/reduction properties.The activity of the monometallic palladium catalyst decreases under steady-state conditions, even at a temperature as low as 470°C. In situ XRD results showed that no decomposition of bulk PdO into metallic palladium occurred at temperatures below 800°C. Hence, the reason for the drop in activity is probably not connected to the bulk PdO decomposition.All Pd–Pt catalysts, independently of the support, have considerably more stable methane conversion than the monometallic palladium catalyst. However, dissimilarities in activity and ability to reoxidise PdO were observed for the various support materials. Pd–Pt supported on Al₂O₃ was the most active catalyst in the low-temperature region, Pd–Pt supported on ceria-stabilised ZrO₂ was the most active between 620 and 800°C, whereas Pd–Pt supported on LaMnAl₁₁O₁₉ was superior for temperatures above 800°C. The ability to reoxidise metallic Pd into PdO was observed to vary between the supports. The alumina sample showed a very slow reoxidation, whereas ceria-stabilised ZrO₂ was clearly faster.

Keywords: Palladium; Platinum; Bimetal; Catalytic combustion; Zirconia; Alumina; Hexaaluminate; Ceria; Yttria; Methane

Exhausted fluid catalytic cracking catalysts as raw materials for zeolite synthesis by Elena I. Basaldella; Julio C. Paladino; Mariana Solari; Graciela M. Valle (pp. 186-191).

The utilization of exhausted fluid catalytic cracking (FCC) catalysts as raw materials for the zeolite synthesis was analyzed. Samples of the catalysts directly released from FCC units and the corresponding impact grinding pretreated samples were used. Mechanical treatment was observed to decrease catalyst crystallinity and particle size. The catalyst reactivity was analyzed in terms of conversion in zeolite and product properties. Hydrothermal synthesis experiments in NaOH medium were performed. Catalysts conversion in A and X type zeolites was obtained for treated and not treated samples. In particular, high conversion in NaX type were achieved using the more siliceous catalyst, whereas grinding activation produces a decrease of particle size and Al/Si ratio of the zeolites obtained.

Keywords: Exhausted catalysts; Catalysts disposal; Zeolite synthesis; X zeolite; Grinding treatments

Synthetic kenyaite as catalyst support for hydrocarbon combustion by Yuri Kalvachev; Vladislav Kostov-Kytin; Silvia Todorova; Krasimir Tenchev; Georgi Kadinov (pp. 192-197).

Synthetic kenyaite is prepared in the system K₂O–SiO₂–H₂O. It is modified with cobalt and platinum in order to obtain catalysts for complete oxidation of n-hexane and benzene. The prepared samples are characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry (TG), differential thermal analysis (DTA), temperature programmed reduction (TPR) and Fourier transformed infrared (FTIR) spectroscopy. Co is loaded on kenyaite using ammonia method and classical impregnation. Bimetallic Co–Pt possess higher catalytic activity than monometallic cobalt for the oxidation of benzene, while, for hexane oxidation, the monometallic cobalt catalysts exhibit higher or close activity to that of Co–Pt samples. The catalysts prepared by ammonia method have better performance due to finer dispersion of the metal particles on the surface of the support.

Keywords: Kenyaite; Cobalt; Platinum; Hydrocarbon oxidation

Mineralization of phenol by a heterogeneous ultrasound/Fe-SBA-15/H₂O₂ process: Multivariate study by factorial design of experiments by Raúl Molina; Fernando Martínez; Juan Antonio Melero; David H. Bremner; Anand G. Chakinala (pp. 198-207).

A novel heterogeneous catalyst has been used for the oxidation of aqueous solutions of phenol by catalytic wet peroxide oxidation assisted by ultrasound irradiation. This composite catalyst material that contains crystalline hematite particles embedded into a mesostructured SBA-15 matrix was used successfully in the oxidation of phenol by heterogeneous Fenton and photo-Fenton processes. Ultrasound is found to enhance the activity of the catalyst in the process, without prejudice to the stability of the iron supported species. The influence of different variables, such as hydrogen peroxide concentration or catalyst loadings in the reaction was studied by factorial design of experiments. Catalyst loadings of 0.6gL⁻¹ and a concentration of hydrogen peroxide close to twice the stoichiometric amount yield a remarkable organic mineralization, accompanied by excellent catalyst stability. The coupled US/Fe-SBA-15/H₂O₂ process at room temperature is revealed as a promising technique for wastewater treatment.

Keywords: Fenton; Ultrasound; CWPO; Heterogeneous catalyst; SBA-15 and phenol

Investigation of the selective catalytic reduction of NO by NH₃ on Fe-ZSM5 monolith catalysts by Oliver Kröcher; Mukundan Devadas; Martin Elsener; Alexander Wokaun; Nicola Söger; Marcus Pfeifer; Yvonne Demel; Lothar Mussmann (pp. 208-216).

Fe-ZSM5 coated on cordierite monolith was investigated in the selective catalytic reduction (SCR) of NO with ammonia over a broad temperature range, applying simulated diesel exhaust gas conditions. The catalyst exhibited over 80% NO_x reduction (DeNOx) from 400 to 650°C at very good selectivity. The dosage of variable amounts of ammonia in the catalytic tests revealed that the SCR reaction is inhibited by ammonia. At very high temperatures DeNOx is reduced due to the selective catalytic oxidation (SCO) of ammonia to nitrogen and the oxidation to NO. Water-free experiments resulted in generally higher DeNOx values, which are explained by the inhibiting effect of water on the NO oxidation capability of Fe-ZSM5. The catalyst was stable upon thermal ageing and only 5–15% loss in DeNOx activity was observed after hydrothermal treatment. This loss in DeNOx is in parallel with a loss of ammonia storage capacity of the aged catalyst. Characterization by NH₃ TPD and MAS²⁷Al NMR spectroscopy revealed dealumination of the zeolite by hydrothermal ageing, which reduces the Brønsted acidity of the catalyst.

Keywords: Fe-ZSM5; NO; _x; conversion; Monolith; Stability; Urea SCR; Ammonia storage

Co₃O₄/CeO₂ composite oxides for methane emissions abatement: Relationship between Co₃O₄–CeO₂ interaction and catalytic activity by L.F. Liotta; G. Di Carlo; G. Pantaleo; A.M. Venezia; G. Deganello (pp. 217-227).

Co₃O₄/CeO₂ composite oxides with different cobalt loading (5, 15, 30, 50, 70wt.% as Co₃O₄) were prepared by co-precipitation method and investigated for the oxidation of methane under stoichiometric conditions. Pure oxides, Co₃O₄ and CeO₂ were used as reference. Characterization studies by X-ray diffraction (XRD), BET, temperature programmed reduction/oxidation (TPR/TPO) and X-ray photoelectron spectroscopy (XPS) were carried out.An improvement of the catalytic activity and thermal stability of the composite oxides was observed with respect to pure Co₃O₄ in correspondence of Co₃O₄–CeO₂ containing 30% by weight of Co₃O₄. The combined effect of cobalt oxide and ceria, at this composition, strongly influences the morphological and redox properties of the composite oxides, by dispersing the Co₃O₄ phase and promoting the efficiency of the Co³⁺–Co²⁺ redox couple. The presence in the sample Co₃O₄(30wt.%)–CeO₂ of a high relative amount of Ce³⁺/(Ce⁴⁺+Ce³⁺) as detected by XPS confirms the enhanced oxygen mobility.The catalysts stability under reaction conditions was investigated by XRD and XPS analysis of the used samples, paying particular attention to the Co₃O₄ phase decomposition. Methane oxidation tests were performed over fresh (as prepared) and thermal aged samples (after ageing at 750°C for 7h, in furnace). The resistance to water vapour poisoning was evaluated for pure Co₃O₄ and Co₃O₄(30wt.%)–CeO₂, performing the tests in the presence of 5vol.% H₂O. A methane oxidation test upon hydrothermal ageing (flowing at 600°C for 16h a mixture 5vol.% H₂O+5vol.%O₂ in He) of the Co₃O₄(30wt.%)–CeO₂ sample was also performed. All the results confirm the superiority of this composite oxide.

Keywords: Methane oxidation; Cobalt oxide-ceria; Redox properties; Thermal-hydrothermal ageing

Mineralization of paracetamol by ozonation catalyzed with Fe²⁺, Cu²⁺ and UVA light by Marcel Skoumal; Pere-Lluís Cabot; Francesc Centellas; Conchita Arias; Rosa María Rodríguez; José Antonio Garrido; Enric Brillas (pp. 228-240).

Acid solutions containing up to 1gl⁻¹ of the drug paracetamol have been treated with ozone alone and ozonation catalyzed with Fe²⁺, Cu²⁺ and/or UVA light at 25.0°C. Direct ozonation yields poor degradation due to the high stability of final carboxylic acids formed, whereas more than 83% of mineralization is attained with the catalyzed methods. Under UVA irradiation, organics can be efficiently destroyed by the combined action of generated H₂O₂ and UVA light. In the presence of Fe²⁺ and UVA light, the process is accelerated due to the production of oxidant hydroxyl radical (OH) and the photodecomposition of Fe³⁺ complexes. The highest oxidizing power is achieved by combining Fe²⁺, Cu²⁺ and UVA light, because complexes of final acids with Cu²⁺ are more quickly degraded than those competitively formed with Fe³⁺. For all catalyzed methods, the initial mineralization rate is enhanced and the percent of degradation generally drops with increasing drug concentration. The paracetamol decay always follows a pseudo-first-order reaction with slightly higher rate constant for catalyzed systems than direct ozonation. Aromatic products such as hydroquinone, p-benzoquinone and 2-hydroxy-4-( N-acetyl)aminophenol are identified by gas chromatography–mass spectrometry (GC–MS) and reversed-phase chromatography. Acetamide is generated when hydroquinone is produced. These products are degraded to oxalic and oxamic acids as ultimate carboxylic acids, as detected by GC–MS and ion-exclusion chromatography. Oxalic acid is generated via glycolic, glyoxylic, tartronic, ketomalonic and maleic acids. While Fe³⁺-oxalato complexes are photolyzed by UVA light, Cu²⁺-oxalato, Fe³⁺-oxamato and Cu²⁺-oxamato complexes are oxidized withOH. NH₄⁺ and NO₃⁻ ions are produced during mineralization.

Keywords: Paracetamol; Ozonation; Catalysis; Water treatment; Oxidation products

Effective Au-Au⁺-Cl_x/Fe(OH)_y catalysts containing Cl⁻ for selective CO oxidations at lower temperatures by Botao Qiao; Youquan Deng (pp. 241-248).

Supported Au catalysts Au-Au⁺-Cl_x/Fe(OH)_y ( x<4, y≤3) and Au-Cl_x/Fe₂O₃ prepared with co-precipitation without any washing to remove Cl⁻ and without calcining or calcined at 400°C were studied. It was found that the presence of Cl⁻ had little impact on the activity over the unwashed and uncalcined catalysts; however, the activity for CO oxidation would be greatly reduced only after Au-Au⁺-Cl_x/Fe(OH)_y was further calcined at elevated temperatures, such as 400°C. XPS investigation showed that Au in catalyst without calcining was composed of Au and Au⁺, while after calcined at 400°C it reduced to Au⁰ completely. It also showed that catalysts precipitated at 70°C could form more Au⁺ species than that precipitated at room temperatures. Results of XRD and TEM characterizations indicated that without calcining not only the Au nano-particles but also the supports were highly dispersed, while calcined at 400°C, the Au nano-particles aggregated and the supports changed to lump sinter. Results of UV–vis observation showed that the Fe(NO₃)₃ and HAuCl₄ hydrolyzed partially to form Fe(OH)₃ and [AuCl_x(OH)4−_x]⁻ ( x=1–3), respectively, at 70°C, and such pre-partially hydrolyzed iron and gold species and the possible interaction between them during the hydrolysis may be favorable for the formation of more active precursor and to avoid the formation of Au–Cl bonds. Results of computer simulation showed that the reaction molecular of CO or O₂ were more easily adsorbed on Au⁺ and Au⁰, but was very difficultly absorbed on Au⁻. It also indicated that when Cl⁻ was adsorbed on Au⁰, the Au atom would mostly take a negative electric charge, which would restrain the adsorption of the reaction molecular severely and restrain the subsequent reactions while when Cl⁻ was adsorbed on Au⁺ there only a little of the Au atom take negative electric charge, which resulting a little impact on the activity.

Keywords: Gold catalyst; CO oxidation; Green chemistry; Preparation; Uncalcined; Unwashed

Oxidation of CO over Ru containing perovskite type oxides by S. Petrović; V. Rakić; D.M. Jovanović; A.T. Bari�?ević (pp. 249-257).

Perovskite type catalysts La_0.7Sr_0.3Cr1−_xRu_xO₃ (0.025≤ x≤0.100) were synthesized by annealing a mixture of metal oxides and carbonates gradually up to 1000°C in air, and characterized by XRPD, XPS, TPD, SEM-EDS and the van der Pauw method. The CO oxidation activity was investigated in a differential recycle reactor. According to the XRPD results, all samples achieved a perovskite structure, with a small presence of SrCrO₄ phase. The XPS results revealed that the surface composition of all samples differed considerably from the stoichiometric value with an important segregation of strontium and mainly ruthenium with regard to chromium at the surface of the catalysts. The sharp decrease of resistivity with increasing surface concentration of ruthenium and the independence of the resistivity on temperature for the sample with x=0.100 imply the possible presence of SrRuO₃, La–Ru–O and highly dispersed RuO₂ (invisible by XRPD), known as good electric conductors, at the surface. The CO oxidation activity increases with increasing the degree of substitution ( x). The surface concentrations of ruthenium are almost the same in the samples with x=0.075 and 0.100. Those samples showed the similar values of resistivity in whole investigated temperature range and very close CO oxidation activity, which indicates that the concentration of Ru⁴⁺ in the surface region and its stability are determining factors for the CO oxidation activity. The main results of this study are that ruthenium perovskites have a high thermal stability and CO oxidation activity.

Keywords: Ruthenium; Perovskite; Electric resistivity; CO oxidation activity

Decolorization of synthetic dyes by hydrogen peroxide with heterogeneous catalysis by mixed iron oxides by Petr Baldrian; Věra Merhautová; Jiří Gabriel; František Nerud; Pavel Stopka; Martin Hrubý; Milan J. Beneš (pp. 258-264).

Heterogeneous catalysts based on magnetic mixed iron oxides (MO·Fe₂O₃; M: Fe, Co, Cu, Mn) were used for the decolorization of several synthetic dyes (Bromophenol Blue, Chicago Sky Blue, Cu Phthalocyanine, Eosin Yellowish, Evans Blue, Naphthol Blue Black, Phenol Red, Poly B-411, and Reactive Orange 16). All the catalysts decomposed H₂O₂ yielding highly reactive hydroxyl radicals, and were able to decolorize the synthetic dyes. The most effective catalyst FeO·Fe₂O₃ (25mgmL⁻¹ with 100mmolL⁻¹ H₂O₂) produced more than 90% decolorization of 50mgL⁻¹ Bromophenol Blue, Chicago Sky Blue, Evans Blue and Naphthol Blue Black within 24h. The fastest decomposition proceeded during the first hour of the reaction. In addition to dye decolorization, all the catalysts also caused a significant decrease of chemical oxygen demand (COD). Individual catalysts were active in the pH range 2–10 depending on their structure and were able to perform sequential catalytic cycles with low metal leaching.

Keywords: Degradation; Synthetic dyes; Hydrogen peroxide; Heterogeneous catalysis; Iron oxides

Preparation and characterization of LaFe1−_xMg_xO₃/Al₂O₃/FeCrAl: Catalytic properties in methane combustion by Fengxiang Yin; Shengfu Ji; Biaohua Chen; Liping Zhao; Hui Liu; Chengyue Li (pp. 265-273).

A series of the LaFe1−_xMg_xO₃/Al₂O₃/FeCrAl catalysts ( x=0–1) were prepared. The structure of the catalysts was characterized using X-ray powder diffraction (XRD), scanning electron microscope (SEM) and temperature-programmed reduction (TPR). The catalytic activity of the catalysts for the methane combustion was evaluated. The catalytic stability of the catalysts for 100h was tested with a fixed bed reactor. The results indicated that in the LaFe1−_xMg_xO₃/Al₂O₃/FeCrAl catalysts the phase structure were the LaFe1−_xMg_xO₃ perovskite-type oxides, α-Al₂O₃ and γ-Al₂O₃. The surface particle shape and size were more different with the variety of the molar ratio of Fe to Mg in the LaFe1−_xMg_xO₃. The Fe component of the LaFe1−_xMg_xO₃/Al₂O₃/FeCrAl catalysts played an important role to the catalytic activity for the methane combustion and the order of the catalytic activity in terms of x was 0.5>0.3>0.7>0.9>0>0.1>1. In the LaFe1−_xMg_xO₃/Al₂O₃/FeCrAl catalysts ( x=0.1–0.9) the Fe and Mg components can promote the thermal stability. There were the stronger interaction among the LaFe1−_xMg_xO₃ perovskite-type oxides and the Al₂O₃ washcoats and the FeCrAl support.

Keywords: Monolithic catalysts; Washcoat; LaFe; 1−; _x; Mg; _x; O; ₃; Methane catalytic combustion; XRD; SEM; TPR

Oxidation catalysts prepared from biosorbents supported on zeolites by H. Figueiredo; I.C. Neves; C. Quintelas; T. Tavares; M. Taralunga; J. Mijoin; P. Magnoux (pp. 274-280).

The catalytic oxidation of 1,2-dichlorobenzene was investigated over NaY and NaX zeolites, loaded with chromium through the action of a robust biosorption system consisting of a bacterial biofilm supported on the zeolites. The results of biosorption showed that the maximum metal removal efficiency was 20%, in both systems based on NaY or NaX, starting from solutions with chromium(VI) concentrations ranging from 50 to 250mg_Cr/L. The bacterial biofilm, Arthrobacter viscosus, supported on the zeolite reduces Cr(VI) to Cr(III). The Cr(III) is retained in the zeolite by ion exchange. The new catalysts were characterized by spectroscopic methods (FTIR ), chemical analyses (ICP-AES), surface analysis (XRD) and thermal analysis (TGA). The various techniques of characterization show that this biosorption process does not modify the morphology and structure of the FAU-zeolites. These catalysts, Cr/FAU, prepared through this new procedure present good activity and selectivity for dichlorobenzene oxidation in wet air at 350°C. The Cr₅₀-Y was selected as the most active, selective and stable catalyst for oxidation of 1,2-dichlorobenzene in wet air.

Keywords: Zeolites; Arthrobacter viscosus; Biosorbents; Cr/FAU; VOCs; Oxidation

NH₃-SCR of NO at low temperatures over sulphated vanadia on carbon-coated monoliths: Effect of H₂O and SO₂ traces in the gas feed by E. García-Bordejé; J.L. Pinilla; M.J. Lázaro; R. Moliner (pp. 281-287).

The objective of this research is to asses the impact of the addition of H₂O, SO₂, and both in the SCR of NO at low temperatures over sulphated vanadia on carbon-coated monoliths. The sulphated catalyst keeps a 100% conversion and total selectivity to N₂ in the low temperature range, i.e. 473–500K, when either H₂O or SO₂ is added to the gas feed. However, a decline of steady state conversion and selectivity occurs when both H₂O and SO₂ are added simultaneously because H₂O speeds up the deposition of ammonium sulphate salts. This decrease of catalyst performance is reversed when the reaction is carried out under dry conditions at temperatures higher than 473K but not at lower temperature (453K). Thus, the catalyst has demonstrated to be a good candidate for the SCR of NO at low temperatures even in stack gases containing traces of undesired components.

Keywords: Carbon-coated monoliths; SCR of NO; Vanadia catalyst

Catalytic decomposition of ozone and para-Chlorobenzoic acid ( pCBA) in the presence of nanosized ZnO by Haeryong Jung; Heechul Choi (pp. 288-294).

This research forwards the evaluating of the efficiency of nanosized ZnO in the application of the catalytic ozonation, determines the reaction kinetics of ozone with the nanosized ZnO, and delineates the characteristics of the decomposition of para-Chlorobenzoic acid ( pCBA) and ozone in catalytic ozonation using the nanosized ZnO particles. It was found that the nanosized ZnO enhanced the degradation of ozone and the catalytic ozonation on the surface of the nanosized ZnO significantly enhanced the degradation of pCBA. In catalytic reactions the degradation of pCBA followed two-stage kinetics, initial rapid removal phase (Phase I) and a slower decomposition phase (Phase II). The total degradation rate of pCBA was well matched with the initial removal of pCBA in Phase I. The R_ct values representing the ratio of hydroxyl radicals [OH] and ozone [O₃] were found to increase with an increased concentration of the nanosized ZnO indicating the enhanced transformation of ozone intoOH.

Keywords: ZnO; Nanoparticle; Ozonation; Catalytic reaction; p; CBA

Preparation of TiO₂ coatings on PET monoliths for the photocatalytic elimination of trichloroethylene in the gas phase by Benigno Sánchez; Juan M. Coronado; Roberto Candal; Raquel Portela; Isabel Tejedor; Marc A. Anderson; Dean Tompkins; Timothy Lee (pp. 295-301).

This paper presents the first data on the performance of polyethylene terephthalate (PET) monoliths as photocatalytic support. For this purpose, first a protective layer of SiO₂ was applied to the polymer to prevent oxidation of the substrate, and subsequently the photoactive layer of TiO₂ was deposited on PET monoliths using the dip-coating technique. In order to increase the adherence of inorganic coatings, two different synthesis procedures were evaluated. One approach was based on reducing the surface tension of the SiO₂ sol using a fluorinated surfactant to increment the PET wettability. The second approach consisted in modifying the PET surface with a layer of the polymer poly(diallyldimethylammonium) chloride (PDDA), which provides a positively charged surface for the fixation of the alkaline SiO₂ sol. Both TiO₂/SiO₂ coated PET monoliths were assayed in a single-pass annular reactor for the destruction of trichloroethylene (TCE). The two coating procedures were compared in terms of homogeneity, durability and photocatalytic activity.

Keywords: Photocatalysis; TiO; ₂; Coating; Polymers; PET; Monoliths; TCE; SEM

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Applied Catalysis B, Environmental (v.66, #3-4)