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Applied Catalysis B, Environmental (v.127, #)

Contents (pp. iii).

Contents (pp. co4).

Editorial Board (pp. co2).

Editorial Board (pp. i).

Mesoporous NiO nanomagnets as catalysts and separators of chemical agents by Mohamed Khairy; Sherif A. El-Safty; Mohamed Ismael; Hiroshi Kawarada (pp. 1-10).

.Display Omitted► Hierarchical mesoporous NiO nano-flower and -sphere magnets were fabricated via simple method. ► The magnetic nanocatalysts show evidence of the activity toward chemical agents. ► The NiO nanomagnets retain their catalytic activity after several reuse cycles. ► The nanoflower magnets show high-gradient separation of organic contaminants from aquatic life.The development of a sustainable catalyst could potentially provide a long-term solution to industrial processes, especial those in the chemical industry, that require the production of a large quantity of raw materials manufactured from renewable resources. Therefore, establishing a proper design for a highly efficient and long-term reusable catalyst is one of the crucial environmental issues facing humanity. In this study, we developed a simple control for hierarchal mesoporous nickel oxide (NiO) nanomagnets (NMs) with flower- and sphere-like morphology and large mesocage cavities. In the fabrication of super-nanostructure NiO, features that were affected by the shape, surface, and size of particles exhibit high catalytic activities of chemical agents, such as o-aminophenol. Our findings shows that the NiO NM with flower-like morphology NFs has higher catalytic activity toward the oxidation of organic contaminates than that of nanospheres NSs or even other magnetic nanoparticles (NPs) such as Fe₃O₄ NPs. Furthermore, the NiO NMs are capable of the high-gradient magnetic separation of organic contaminants from aquatic life with excellent reusability even after several cycles, which may help in wastewater management and supply. To understand the effectiveness of NiO NM functionalities in terms of hierarchical mesocage parameters, as well as in terms of shape- and size-morphologies in such chemical reactions, surface interaction and magnetic separation with chemical agents and theoretical calculations were performed.

Keywords: Mesoporous; Nickel oxide; Nanomagnet; Chemical oxidation; Organic pollutants

Adjustable kinetics in heterogeneous photocatalysis demonstrating the relevance of electrostatic interactions by Jan Ungelenk; Claus Feldmann (pp. 11-17).

Display Omitted► Model for electrostatic interaction of dyes and photocatalysts. ► Reaction order depending on pH and charge of dye. ► Kinetic-order paradox reliably addressed. ► Multi-component view taking electric double layer of photocatalyst into account.The performance of a photocatalyst depends on a complicated correlation of a multitude of parameters including extrinsic ones. Among, the pH value is probably the most important parameter. Gaining a detailed knowledge of the underlying processes still represents a major challenge but is required to optimize known or to develop efficient novel photocatalysts. Here, we present a favorable model system comprising nano-β-SnWO₄ as the photocatalyst and azo-dyes in different charge states. Disentangling parameters, we demonstrate that the reaction order of our exemplary photocatalytic degradation reaction can be fully tuned from first over zero- to mixed-order by simply adjusting the pH. Thereby we elucidate the importance of electrostatic interactions which are of significance to various aspects including: the decomposition of non-charged persistent pollutants, the inactivation of bacteria as well as the influence of electrolyte containing media, the polarity of the solvent or of specific crystal facets. Based on our results, we suggest taking the electric double layer on the photocatalyst into account. This multi-component view reconciles reported contradictions and allows interpreting results that have been intriguing or misunderstood so far.

Keywords: Photocatalysis; Kinetics; Electrostatic interaction; In situ; measurement; Tin tungstate

Electrochemical promotion of methane oxidation on impregnated and sputtered Pd catalyst-electrodes deposited on YSZ by F. Matei; D. Ciuparu; C. Jiménez-Borja; F. Dorado; J.L. Valverde; S. Brosda (pp. 18-27).

Display Omitted► As prepared sputtered Pd films on YSZ electrochemically promote CH₄ combustion. ► Impregnated Pd films on YSZ electropromote CH₄ combustion only after reduction. ► The former exhibit Faradaic efficiencies a factor of 10 higher than the latter. ► Coexistence of PdO and Pd phases needed for catalytic rate and electropromotion.The microstructure and electrochemical promotion of thin Pd catalyst-electrodes deposited on yttria-stabilized zirconia (YSZ) prepared either by sputter-deposition or wet impregnation has been studied for the complete oxidation of methane using XRD, XPS and steady state catalytic measurements in conjunction to electrochemical studies at temperatures 350–460°C under various CH₄ to O₂ ratios. As prepared sputtered catalyst electrodes, which consist mainly of a Pd metal phase are able to electrochemically promote the CH₄ oxidation, while impregnated films, which mainly consist of a PdO phase, can be electropromoted only after in situ reduction. On both types of catalyst-electrodes the reaction exhibits electrophobic behavior under all experimental conditions of this study, i.e. the rate increases moderately with anodic polarization. For sputtered samples, negative current application causes a decrease of the catalytic rate which remains lower than the initial open circuit rate after current interruption. This is a new type of permanent electrochemical promotion and a poisoning index, β, is introduced to quantify the magnitude of this effect.

Keywords: Methane oxidation; Electrochemical promotion; Pd catalyst-electrode; Wet impregnation; Sputtered catalyst-electrodes

A new sight on hydrogenation of F and N-F doped {001} facets dominated anatase TiO₂ for efficient visible light photocatalyst by Wei Wang; Chunhua Lu; Yaru Ni; Mingxing Su; Zhongzi Xu (pp. 28-35).

.Display Omitted► F will substitute the O during the preparation of {001} facets dominated TiO₂. ► N and F located in TiO₂ can be removed completely by hydrogenation. ► Different Ti³⁺ and O_vac will locate by N-F doping and hydrogenation. ► Disorder structure and defect energy state belt enhance the photoactivity.Nonmetal doping such by N and F has been studied widely to enhance the visible light photoactivity of TiO₂. Recently, hydrogenation of pure and N doped TiO₂ is also well studied by theoretical calculations. However, little experimental evidence is known about the nature of the hydrogenation effect played on F and N-F doped anatase TiO₂. In this study, hydrogenation of F and N-F doped {001} facets dominated anatase TiO₂ were prepared by annealing the doped photocatalysts in the 10-bar H₂ atmosphere. Electron paramagnetic resonance (EPR) spectra confirmed the presence of different coordinated Ti³⁺ and oxygen vacancies located in the hydrogenated N and N-F doped TiO₂ as a result of removing the already located N and F species. The visible-light photocatalytic activity of hydrogenated N-F doped TiO₂ was significantly enhanced because of the formation of defect energy state belts and disorder structures. This study gives a new sight on the interaction between H and N, F species in doping TiO₂ and developing efficient visible light photocatalyst by hydrogenation.

Keywords: Ti; ³⁺; Visible light photocatalysis; Doping; Oxygen vacancy; {0; 0; 1} facets

Catalytic activities of Fe₂O₃ and chromium doped Fe₂O₃ for sulfuric acid decomposition reaction in an integrated boiler, preheater, and catalytic decomposer by A.M. Banerjee; A.R. Shirole; M.R. Pai; A.K. Tripathi; S.R. Bharadwaj; D. Das; P.K. Sinha (pp. 36-46).

Display Omitted► Performance of Fe₂O₃/Fe_1.8Cr_0.2O₃ granules for H₂SO₄ decomposition step in SI cycle. ► New design of integrated high temperature quartz catalytic reactor. ► Sustainability of activity over 20g catalyst for 100h at 800°C, flux 0.63mlmin⁻¹. ► Characterization of fresh/spent catalyst to study stability/most probable mechanism. ► Cr substitution induced facile sulfate decomposition and superior redox properties.In our earlier work (Banerjee et al. [29]) we have reported the catalytic properties of powders of Fe2(1− x₎Cr2_xO₃ ( x=0.0, 0.1, 0.2) for sulfuric acid decomposition in a flow through quartz catalytic reactor with 2g catalyst in presence of nitrogen as a carrier gas. With a practical application approach, in this work the two screened oxides, iron oxide and 10% chromium doped iron oxide, that showed good initial promise as catalyst for sulfuric acid decomposition were prepared in granular form and evaluated for sulfuric acid decomposition reaction using an indigenously developed dual tube quartz reactor which served as an integrated acid boiler, pre-heater, and decomposer. The effect of reaction variables, e.g., temperature, time, and acid flow rate on the catalytic activity was evaluated in detail employing 20g of granular catalyst and 98wt% H₂SO₄ (without any carrier/diluents gas). Temperature dependent catalytic activity results revealed that at lower temperatures (<775°C) the Cr-doped sample showed much higher activity while at higher temperatures (∼825°C) the conversions levels were found to be similar on both the samples. No decrease in catalytic activity was observed for either catalysts during a 100h catalytic run at 800°C and at an acid flux of ∼0.63mlmin⁻¹, but the chromium doped sample exhibited slightly higher activity over the entire time period. Both the catalyst exhibited a loss in catalytic activity when subjected to higher flow rates of sulfuric acid in the range 2–10mlmin⁻¹. The catalytic activities were correlated with the structure, morphology, redox, and thermal properties of the oxides by proper characterization of the fresh and the spent catalysts by XRD, FTIR, XPS, TPR, evolved gas analysis, and SEM. From the ex situ analysis of the spent catalyst samples the most probable mechanism of the high temperature sulfuric acid decomposition reaction was also proposed, which involves metal sulfate formation and decomposition steps. The enhanced catalytic activity of Cr-doped Fe₂O₃ was ascribed to lower thermal stability of its sulfate and better redox properties.

Keywords: Hydrogen production; Sulfuric acid decomposition; Iron oxide; Chromium doped iron oxide; Granular catalyst; Redox

Three-dimensionally ordered macroporous Au/CeO₂-Co₃O₄ catalysts with nanoporous walls for enhanced catalytic oxidation of formaldehyde by Baocang Liu; Yang Liu; Changyan Li; Wenting Hu; Peng Jing; Qin Wang; Jun Zhang (pp. 47-58).

Display Omitted► 3DOM Au/CeO₂-Co₃O₄ catalysts having adjustable pore sizes and nanoporous wall skeleton were created. ► The 3DOM Au/CeO₂-Co₃O₄ catalysts exhibited superior catalytic activity for HCHO oxidation. ► A synergistic effect catalytic mechanism was proposed to account for the enhanced HCHO catalytic oxidation.Three-dimensionally ordered macroporous (3DOM) Au/CeO₂-Co₃O₄ catalysts were created via a precursor thermal decomposition-assisted colloidal crystal templating method. The 3DOM Au/CeO₂-Co₃O₄ catalysts possessed well-defined 3DOM structures with adjustable pore sizes, and their compositions, phase structures, and surface elemental valence states can be well controlled by solely adjusting the Ce/Co molar ratio. Moreover, the nanoporous walls with pore sizes around ∼3–4nm were created in 3DOM Au/CeO₂-Co₃O₄ catalysts through the thermal decomposition of Co and Ce oxalate precursors during the preparation. The 3DOM Au/CeO₂-Co₃O₄ catalysts exhibited superior catalytic activity for formaldehyde (HCHO) catalytic oxidation into CO₂ and H₂O with a 100% conversion rate at temperatures as low as ∼39°C. A catalytic mechanism of the synergistic effect between CeO₂ and Co₃O₄ supports, which greatly accelerates the surface active oxygen migration and activates the Au species, was proposed for explaining the enhanced HCHO catalytic oxidation over 3DOM Au/CeO₂-Co₃O₄ catalysts. The well-controlled method for creation of 3DOM Au/CeO₂-Co₃O₄ catalysts with nanoporous walls could be adopted for generation of other catalytic materials with mixed macroporous and mesoporous structures. The superior catalytic activity of 3DOM Au/CeO₂-Co₃O₄ catalysts makes them potentially applicable to indoor HCHO decontamination and industrial catalysis.

Keywords: Three-dimensionally ordered macroporous; Au/CeO; ₂; -Co; ₃; O; ₄; catalysts; HCHO catalytic oxidation; Synergistic effect; Catalytic mechanism

Cobalt hydrotalcites as catalysts for bioethanol steam reforming. The promoting effect of potassium on catalyst activity and long-term stability by Raúl Espinal; Elena Taboada; Elies Molins; Ricardo J. Chimentao; Francesc Medina; Jordi Llorca (pp. 59-67).

Display Omitted► K is a promoter of Co/Mg/Al hydrotalcite-derived catalysts for ethanol reforming. ► Little carbon is generated under practical conditions using commercial bioethanol. ► Co spinel particles transforms into CoO strongly interacting with MgO. ► No metallic cobalt is detected after reaction.Cobalt hydrotalcite-derived catalysts, doped with potassium, are active materials for the ethanol steam reforming reaction. Potassium addition reduces the acid sites number and strength. It acts as a promoter of the ethanol steam reforming (ESR); ethanol conversion is higher at lower temperature, as the amount of potassium at the surface of the catalyst increases. The catalysts are stable for long-term experiments (300h) under high loads of ethanol and bioethanol (0.036g_EtOHmin⁻¹, H₂O:CH₃CH₂OH=4:1 molar). Moreover, they generate a low amount of carbon (0.0067g_Cg_catalyst⁻¹h⁻¹). The catalysts after reaction contain almost exclusively high spin Co²⁺ in cobalt oxide (or in (Co,Mg)O); only traces of metallic cobalt are identified by magnetometry, <0.1wt.% Co⁰, suggesting that oxidized cobalt is an active species in ESR.

Keywords: Hydrogen; Ethanol reforming; Bioethanol; Cobalt catalyst; Hydrotalcite-derived catalyst; Honeycomb

Characterization of thermally treated Co²⁺-exchanged zeolite X by Hoon Young Jeong; Dong-Chan Koh; Kwang-Sik Lee; Hyun Hwi Lee (pp. 68-76).

Display Omitted► At ≤600°C, Co²⁺-exchanged zeolite X (CoX) maintains the zeolite framework. ► At ≤600°C, cobalt is present as 6-fold coordinated Co²⁺ in exchange sites. ► At ≥800°C, CoX transforms to glassy material and secondary crystalline phases. ► At ≥800°C, cobalt is incorporated into a CoAl₂O₄(s)-like phase.This study investigated thermal stabilization of Co²⁺-exchanged zeolite X (CoX) using scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), and leaching tests. From SEM-EDX analysis, cobalt was dispersed randomly at ≤600°C, suggesting its presence as an extraframework cation in exchange sites. At ≥800°C, cobalt was locally concentrated with Al on the vitreous surface. Consistent with such observations, XRD data indicated that CoX maintained the zeolite framework at ≤600°C, and that it became vitrified and transformed to nepheline (NaAlSiO₄(s)) and cobalt aluminate (CoAl₂O₄(s)) at ≥800°C. Cobalt-K edge XAS was subjected to both X-ray absorption near-edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) analyses. In XANES spectra, the pre-edge peaks and edge-shoulders, characteristic of 4-fold coordinated cobalt (e.g., CoAl₂O₄(s)), were not evident at ≤600°C, but such features were strong at ≥800°C. The EXAFS spectra of CoX at ≤600°C lacked in the coordination shells beyond the first CoO shell. In contrast, CoX at ≥800°C showed the EXAFS spectra similar to CoAl₂O₄(s). Taken together, cobalt was likely present as 6-fold coordinated Co²⁺ in exchange sites at ≤600°C and mainly incorporated into a non-exchangeable CoAl₂O₄-like phase in both vitreous and crystalline forms at ≥800°C. In agreement with this proposition, leaching tests with concentrated CaCl₂ solutions supported the greater stability of cobalt at ≥800°C.

Keywords: Radioactive isotope; Cobalt; Zeolite; EXAFS; SEM

Oxygen defects: The key parameter controlling the activity and selectivity of mesoporous copper-doped ceria for the total oxidation of naphthalene by Asunción Aranda; Said Agouram; Jose M. López; Ana M. Mastral; David R. Sellick; Benjamín Solsona; Stuart H. Taylor; Tomás García (pp. 77-88).

Display Omitted► Copper-doped mesoporous ceria is an effective catalyst for naphthalene total oxidation. ► The addition of copper increases the concentration of surface defects. ► The concentration of surface defects correlates with catalytic activity.Mesoporous CeO₂ modified by the addition of copper has shown high efficiency for the total oxidation of naphthalene. High activity and 100% selectivity to carbon dioxide throughout the whole range of temperatures studied were achieved for copper loadings of 3.6% and lower. The catalytic behaviour has been related to the concentration of surface oxygen defects. A clear correlation between the concentration of surface oxygen defects (determined by XPS and DRIFTS) and the catalytic performance has been identified. Catalytic activity increased as copper was incorporated into the ceria up to 3.6%. In this range of copper content the copper was incorporated into the cubic fluorite lattice of CeO₂ and this was confirmed using XRD and electron diffraction studies. For copper ceria catalysts with higher copper contents the concentration of oxygen defects decreased and an additional dispersed monoclinic CuO phase with a low intrinsic activity was formed, thus leading to a decrease of both the activity and the selectivity to CO₂.

Keywords: Catalytic oxidation; Mesoporous copper doped CeO; ₂; Naphthalene; VOC; PAH

Effect of calcium dopant on catalysis of Ir/La₂O₃ for hydrogen production by oxidative steam reforming of glycerol by Guangxing Yang; Hao Yu; Xiaoya Huang; Feng Peng; Hongjuan Wang (pp. 89-98).

Display Omitted► Ir/La₂O₃ efficiently catalyzes oxidative steam reforming of glycerol. ► Ca as promoter improves stability of Ir/La₂O₃. ► Ca doping in La₂O₂CO₃ eliminates coking. ► Ca improves the dispersion of catalyst via strong metal–support interaction.The superfluous glycerol derived from biodiesel production can be a low-cost feedstock for hydrogen production via reforming technology. In this work, a La₂O₃ supported iridium catalyst was employed to catalyze the oxidative steam reforming of glycerol (OSRG) for hydrogen production, in the range of S/C ratio of 1–3, C/O ratio of 0.75–1 and 550–750°C. The catalyst was modified with Na, Mg and Ca to optimize the catalytic performance in OSRG reaction. It was found that Ca is promising in promoting Ir/La₂O₃ catalyst for OSRG, offering excellent activity, hydrogen selectivity and stability. By combining multiple techniques, i.e. XRD, FTIR, Raman, XPS, H₂-TPR, CO₂-TPD and HRTEM, the Ca modified Ir/La₂O₃ catalyst was characterized to understand the role of Ca promoter. Multi-functions of Ca were demonstrated, including inducing structural defects of La₂O₂CO₃, endowing the catalyst strong basicity and tuning the metal–support interaction, which make the catalyst highly resistant to coking and sintering, therefore performing excellent long-term stability for 100h.

Keywords: Iridium; La; ₂; O; ₂; CO; ₃; Reforming; Glycerol; Calcium

Comparison of precious metal oxide/titanium monolith catalysts in wet oxidation of wastewaters by Arezoo M. Hosseini; Antal Tungler; Zoltán Schay; Sándor Szabó; János Kristóf; Éva Széles; László Szentmiklósi (pp. 99-104).

Display Omitted► Ru/Ir oxide/Ti monolith catalysts showed remarkable catalytic activity in WO. ► Good catalytic activity is tied to the uniform distribution of the two oxides. ► Beneficial was the fragmented structure of Ru and Ir oxides. ► Commercial mesh was most stable among the condition of wastewater wet oxidation. ► Loss of precious metal content was observed during longer usage.CWO (catalytic wet oxidation) of a process wastewater and phenolate solution was carried out at 230°C, 200°C and total pressure of 50bar, with oxygen, in a stainless steel autoclave. Monolith Ti mesh supported precious metal oxide catalysts were characterized with XPS, ICP-MS, SEM and their activity compared in oxidation of model and real wastewaters.The Ru/Ir oxide coated Ti monolith catalysts showed remarkable catalytic activity in wet oxidation both in the overall oxidation expressed by COD (chemical oxygen demand) decrease and in the carbon mineralization expressed by TOC (total organic carbon) decrease. This was valid for the real pharmaceutical wastewater as well as for a phenolate solution too. Meshes containing Ru, Pd and Ir oxide alone were less active than Ru/Ir together on Ti. This observation is in accordance with the electrochemical properties of the same mesh used in hypochlorite production.The commercial mesh was most stable under the conditions of wet oxidation, however the loss of its precious metal content was observed during longer usage. The Ru/Ir monolith catalysts prepared in our laboratories had similar initial activity but they were less stable, the leaching and/or abrasion of the surface precious metal oxide layer was faster, independently of that their had fragmented or continuous structure, resulting from the preparation methods.The loss of activity during longer usage can be the result of deposition of iron and silicon oxides too, as showed by SEM (scanning electron microscopy) analysis.An important feature of the good catalytic activity of the Ru/Ir oxide coated Ti mesh can be the uniform distribution of the two oxides showed by LA–ICPMS (laser ablation–inductive coupled plasma mass spectrometry). According to XPS (X-ray photoelectron spectroscopy) results, the upper surface layer of the catalysts is covered by a mixture of Ru–Ir–Ti oxide of approximately 0.1:0.02:1 atomic ratio for commercial catalyst, and an 0.5:0.7:1.0 atomic ratio for catalysts prepared in our laboratories. We suppose that such mixture of oxides with uniform distribution are the carrier of the good catalytic activity.

Keywords: Wastewater; Wet oxidation; Ti mesh; Ru; Ir; Ti mixture of oxides; Monolith catalyst

Room-temperature catalytic oxidation of benzo(a)pyrene by Ce-SBA-15 supported active CeSiO₄ phase by Xuebin Zhang; Shaomin Liu; Hongwu Tong; Guoping Yong (pp. 105-111).

Display Omitted► CeSiO₄ phase was in situ formed during synthesis of Ce-SBA-15 mesoporous materials. ► Ce-SBA-15 possess of higher adsorption capacity for BaP than SBA-15. ► BaP can be transferred to corresponding quinone by CeSiO₄ at room temperature. ► BaP transfer to corresponding quinone was ascribed to radical oxidation mechanism.A series of cerium-incorporated SBA-15 mesoporous materials were prepared through direct hydrothermal synthesis method, which was characterized by PXRD, N₂ physisorption and TEM measurements. The low-angle PXRD and N₂ physisorption results show the cerium successfully incorporated into the framework of SBA-15. The large angle PXRD results indicate that Ce-SBA-15 mesoporous materials supported CeSiO₄ phase was in situ synthesized by adjusting pH to 6 with anhydrous triethylamine, and then calcined in air at 550°C. The room-temperature adsorption behaviors of SBA-15 and Ce-SBA-15 materials for benzo(a)pyrene in cyclohexane solutions were investigated. Interestingly, Ce-SBA-15 materials reveal good catalytic performance for room-temperature oxidation benzo(a)pyrene to corresponding quinone through a radical oxidation mechanism, attributable to in situ forming active CeSiO₄ phase which was supported in Ce-SBA-15 material. The benzo(a)pyrene transfer to quinone by CeSiO₄ phase leads to higher adsorption capacity owing to higher affinity of quinone with mesoporous channels, as a result, some Ce-SBA-15 materials exhibit higher adsorption capacity for benzo(a)pyrene than SBA-15 material. The radical oxidation mechanism was demonstrated by EPR and the interception effect of a radical scavenger, TEMPO. The quinone-type molecule was identified by photoluminescence, ESI-MS, IR and NMR.

Keywords: Ce-SBA-15; CeSiO; ₄; Benzo(a)pyrene; Room-temperature oxidation

Effect of deposition of silver on structural characteristics and photoactivity of TiO₂-based photocatalysts by E. Pulido Melián; O. González Díaz; J.M. Doña Rodríguez; G. Colón; J.A. Navío; M. Macías; J. Pérez Peña (pp. 112-120).

Display Omitted► A highly photoactive homemade photocatalyst was modified by silver deposits. ► The liquid impregnation method resulted in photocatalysts with higher activity. ► Photoactivity of 0.3Ag-iTiO₂ was higher than that of P25 for several pollutants. ► Its efficiency decreases only slightly after the first use. ► 0.3Ag-iTiO₂ sediments quickly and so, its reutilization would be possible.The homemade bare TiO₂ photocatalyst obtained in a previous work was modified with nanosized silver particles by liquid impregnation and photodeposition methods to obtain different noble metal loadings (0.3–1at.%). Characterization of the synthesized photocatalysts was carried out by the BET method, XPS, TEM, SEM-EDX, XRD and diffuse reflectance measurements. Photocatalytic activity of these silver-deposited TiO₂ nanoparticles was tested by photocatalytic degradation of phenol as a reference model representing phenolic pollutants. The noble metal content on the TiO₂ surface affected the efficiency of the photocatalytic process, and the photocatalytic activity of noble metal-modified TiO₂ was considerably better than that of bare TiO₂. Phenol decomposition rate was higher with TiO₂ modified by the liquid impregnation method than with TiO₂ modified by the photodeposition method.

Keywords: TiO; ₂; Silver; Impregnation; Photodeposition; Photocatalysis; Phenol

HAN and ADN as liquid ionic monopropellants: Thermal and catalytic decomposition processes by Rachid Amrousse; Keiichi Hori; Wafa Fetimi; Kamal Farhat (pp. 121-128).

Display Omitted► Best results are obtained for the most concentrated HAN and ADN solutions. ► Good catalytic activity is demonstrated by low decomposition temperature. ► Fast reaction rate and large amount of products allow to choice the best catalyst. ► Best catalyst/monopropellant combinations: Ir-based/HAN_95% and CuO-based/ADN_75%.Binary HAN and ADN aqueous solutions have been synthesized, then thermally and catalytically decomposed. Binary HAN mixtures were prepared with different concentrations: 95, 80 and 60wt.%. Whereas ADN solution contains are: 75, 60 and 50wt.%. The candidate catalysts were prepared by impregnation of alumina doped by lanthanum oxide with active phase precursors: iridium for HAN and copper oxide for ADN and characterized by transmission electron microscopy, X-ray diffraction and chemisorption. The decomposition processes were followed by thermal analysis and a constant batch reactor. This work shows the essential effect of monopropellant concentrations to determine the best green propellants for industrial applications as reaction control systems. Moreover, HAN and ADN solutions are more efficient for catalytic decomposition due to the absence of stabilizer to inhibit catalysts. The (10%)Ir/Al₂O₃–La₂O₃+HAN_95% and the (10%)CuO/Al₂O₃–La₂O₃+ADN_75% associations show lower decomposition temperatures, larger reaction rates and leads to higher amount of gas phase products, giving the most efficient systems.

Keywords: Monopropellant; HAN; ADN; Catalytic decomposition process

Active size-controlled Ru catalysts for selective CO oxidation in H₂ by Yun Ha Kim; Jung Eun Park; Hyun Chul Lee; Sun Hee Choi; Eun Duck Park (pp. 129-136).

Display Omitted► The Ru dispersion can be controlled through thermal treatment in the presence of H₂ and O₂. ► There exists an optimum Ru particle size in Ru/Al₂O₃ for the selective CO oxidation in H₂. ► The reduced Ru catalyst is superior to the oxidized one for CO oxidation.We propose an activation method to control Ru particle size in supported Ru catalysts, viz. commercial Ru/Al₂O₃ and home-made Ru/SiO₂, in order to increase the catalytic activity for the preferential CO oxidation (PROX). Ru particle size is controlled by adjusting pre-treatment conditions and it affects the catalytic activity for the PROX over supported Ru catalysts. Several measurements: inductively coupled plasma-atomic emission spectroscopy (ICP-AES), bright-field transmission electron microscopy (TEM), X-ray absorption fine structure (XAFS), CO chemisorption, and O₂ chemisorption were conducted to characterize the catalysts. The co-presence of H₂ and O₂ is essential for controlling the Ru particle size accurately. The PROX activity especially at low temperatures increases with increasing particle size of Ru, which seems to be closely related to the adsorption behavior of O₂ on Ru surface.

Keywords: Selective CO oxidation; Ru catalysts; Pretreatment; CO oxidation; Size effect

The influence of silicon on the catalytic properties of Cu/SAPO-34 for NO_x reduction by ammonia-SCR by Jun Wang; Tie Yu; Xinquan Wang; Gongshin Qi; Junjie Xue; Meiqing Shen; Wei Li (pp. 137-147).

Display Omitted► Cu/SAPO-34 performs excellent SCR activity and good hydrothermal stability. ► The contents of Si can directly affect the structure of Cu/SAPO-34 catalysts. ► The Cu loading depends on both the Si contents and the Al contents of HSAPO-34. ► The density of the acidity of Cu/SAPO-34 is affected by the Si contents. ► The Si and Al contents affect the environment of Cu²⁺ species in Cu/SAPO-34.The effect of Si content in SAPO-34 on NO selective catalytic reduction over Cu/SAPO-34 catalyst was investigated. Three fresh catalysts with different Si contents, prepared by the same procedure, showed different NO conversions from 120°C to 600°C. These catalysts were characterized in detail by various techniques (ICP, XRD, SEM, NMR, NH₃-TPD, H₂-TPR and EPR). The NH₃-TPD results indicate that the number of acid sites in Cu/SAPO-34 catalyst increases with increasing Si contents and the SCR activities of the samples correlate well with the number of acidic sites at low temperatures (200°C). The EPR and H₂-TPR results show that both the Si and the Al contents affect the number of isolated Cu²⁺ ions in Cu/SAPO-34 catalysts. The catalysts aged at 750°C for 12h showed higher SCR activities than those of the untreated samples, consistent with the higher numbers of the isolated Cu²⁺ ions.

Keywords: Cu/SAPO-34; Si content; NH; ₃; -SCR; EPR; NMR

Nitrate reduction by maghemite supported Cu-Pd bimetallic catalyst by Junyoung Jung; Sungjun Bae; Woojin Lee (pp. 148-158).

.Display Omitted► Maghemite/Cu/Pd showed excellent catalytic nitrate reduction (99.5%). ► Cu loading at 0.5wt.% showed the highest N₂ gas selectivity (43%). ► Pd loading at 0.25wt.% showed the highest N₂ gas selectivity (47%). ► Lower H₂ flow rates enhanced N₂ gas selectivity. ► Maghemite/Cu/Pd showed stable nitrate removal during three reaction cycles.We have investigated the catalytic nitrate reduction by maghemite supported Cu-Pd bimetallic catalyst (maghemite/Cu/Pd). BET, XRD, XPS, TPR, SEM/EDX, TEM analysis were carried out to characterize maghemite/Cu/Pd. Remarkable nitrate removal (99.5%) by maghemite/Cu/Pd was observed in 90min, while Cu-Pd catalyst supported with alumina (43%) and hematite (63%) showed less efficient nitrate removal. Nitrate removal was excellent (>95%) in all Cu loading variation (0.25–1wt.%) on maghemite/Cu/Pd, while selectivity of nitrogen gas formed during the reaction was the highest (43%) at a specific Cu/Pd ratio (0.5/0.5wt.%). We also observed excellent nitrate removals (>95 and >94%, respectively) by maghemite/Cu/Pd in the ranges of Pd loading (0.25–1wt.%) and hydrogen flow rate (100–500cc/min). The highest nitrogen selectivities (47 and 45%) were obtained by low Pd loading (0.25wt.%) and hydrogen flow rate (200cc/min). Maghemite/Cu/Pd showed slow decrease of nitrate removal (99.5–83%) and low metal leaching (1.5% of Cu leaching) during three reaction cycles. XPS analysis revealed that Cu(0) was oxidized to Cu₂O and CuO during the catalytic nitrate reduction, while Pd(0) was not changed.

Keywords: Maghemite; Bimetallic catalyst; Catalytic nitrate reduction; Nitrogen gas selectivity

Catalytic oxidation of dichloromethane over Pt/CeO₂–Al₂O₃ catalysts by Qiu-Yan Chen; Na Li; Meng-Fei Luo; Ji-Qing Lu (pp. 159-166).

Display Omitted► CeO₂–Al₂O₃ catalysts are effective for catalytic oxidation of dichloromethane. ► The enhanced activity is due to synergy of surface acidity and redox property of the catalyst. ► Pt addition further promotes the reducibility of the catalyst and thus the activity.A series of CeO₂–Al₂O₃ catalysts with different CeO₂ contents were prepared by a co-precipitation method, and supported Pt/CeO₂–Al₂O₃ catalysts were also prepared by an impregnation method. These catalysts were tested for catalytic oxidation of dichloromethane (CH₂Cl₂). It was found that these catalysts were active for the reaction, with a 100% conversion of CH₂Cl₂ obtained at 410°C over a catalyst with 15% of CeO₂. Various characterization results such as ammonia temperature programmed desorption, hydrogen temperature programmed reduction suggested that the catalytic behaviors were synergistically influenced by surface acidity and redox property of the catalysts. An optimal combination of surface acidity and redox property in the catalyst resulted in a high activity. Moreover, the addition of Pt could further enhance the activity, due to the promotion of surface acidity by the introduction of chlorine species in the catalyst during the preparation using H₂PtCl₆ as the precursor and reducibility of the catalyst probably via the formation of Ce–Pt–O solid solution.

Keywords: CeO; ₂; –Al; ₂; O; ₃; Pt catalysts; Catalytic oxidation; Dichloromethane; Surface acidity; Redox property

Transformation and reduction of androgenic activity of 17α-methyltestosterone in Fe₃O₄/MWCNTs–H₂O₂ system by Xiao-bin Hu; Yue-hua Deng; Zhan-qi Gao; Ben-zhi Liu; Cheng Sun (pp. 167-174).

Display Omitted► Competitive oxidation was discussed to explain the adsorption–degradation kinetic mechanism. ► The degradation mechanism was proposed based on the intermediates and the Gaussian calculation. ► The change of androgenic activity of the water was investigated during the catalytic reactions.A heterogeneous Fenton catalyst, multiwalled carbon nanotubes (MWCNTs)–supported Fe₃O₄ nanoparticles, Fe₃O₄/MWCNTs was evaluated through the adsorption and degradation of a trace steroidal endocrine disrupting compound (EDC) 17α-methyltestosterone (MT) in water and in the presence of H₂O₂, respectively. The androgenic activity of the treated water was investigated during the catalytic reactions by human androgen ELISA test. The degradation mechanism of MT by Fe₃O₄/MWCNTs catalysis was discussed on the basis of GC–MS analysis of the intermediates and the theoretical calculation of frontier electron densities and bond dissociation enthalpies of CH and OH of MT molecule. Competitive oxidation could help to understand that the adsorption of trace MT onto the catalyst was favorable to MT degradation byOH, which was confirmed by electron spin resonance spin-trapping technique. The results showed that Fe₃O₄/MWCNTs–H₂O₂ system could not only degrade MT but also remove its androgenic activity. The novel catalyst would be of potential application in water treatment for removing natural and synthetic hydrophobic trace pollutants.

Keywords: Fe; ₃; O; ₄; /MWCNTs nanocomposites; Heterogeneous Fenton; 17α-Methyltestosterone; Degradation mechanism; Androgenic activity

Mesoporous Fe-doped TiO₂ sub-microspheres with enhanced photocatalytic activity under visible light illumination by Chin Jung Lin; Ya Hsuan Liou; Yichi Zhang; Chi Liang Chen; Chung-Li Dong; Szu-Ying Chen; Galen D. Stucky (pp. 175-181).

Display Omitted► A rapid and scalable route to obtain an efficient visible-light-sensitive mesoporous Fe-doped TiO₂ sub-microspheres. ► The substitution of Ti⁴⁺ by Fe³⁺ ions uniformly occurs within such mesoporous sub-microspheres. ► The maximum rate of pharmaceutical photodegradation is increased by 4 times.Mesoporous Fe-doped TiO₂ sub-microspheres (m-Fe-TMS) with high surface area, accessibility, and crystallinity were prepared using a rapid and continuous aerosol-assisted self-assembly (AASA) process for visible-light photocatalytic degradation of persistent pharmaceuticals. The results of X-ray absorption near-edge structure (XANEX) spectroscopy indicate that iron exists as octahedrally coordinated Fe³⁺ ions substituting Ti⁴⁺ in the TiO₂ lattice. The similarity of the Fe/Ti ratios in the bulk and on the surface, as determined by energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS), reveals that the substitution of Ti⁴⁺ by Fe³⁺ ions uniformly occurs within m-Fe-TMS. UV–vis diffuse reflectance spectroscopy shows that m-Fe-TMS exhibits a shift in the absorption threshold toward the visible spectrum. Under visible light irradiation, m-Fe-TMS exhibits a maximum rate of pharmaceutical photodegradation four times that of m-TMS. The photocatalytic degradation rates are reproducible with m-Fe-TMS, even after 10 repeated runs. The formation of chemical FeOTi bonds, and not of isolated Fe₂O₃ particles, leads to the inhibition of photocorrosion and leaching in the photocatalytic reactions. The ease and scalable production of m-Fe-TMS using the AASA process will facilitate the development of visible light-driven photocatalysts for decomposition of environmental contaminants.

Keywords: Mesoporous; Titania; Photoactivity; Visible light

Heterogeneous oxidation of naproxen in the presence of α-MnO₂ nanostructures with different morphologies by Yiping Zhang; Yulong Yang; Yan Zhang; Tuqiao Zhang; Miaomiao Ye (pp. 182-189).

Display Omitted► α-MnO₂ with different morphologies were synthesized via a hydrothermal method. ► The oxidation kinetics of naproxen were modeled by Langmuir–Hinshelwood equations. ► α-MnO₂ nanorods can be recycled without decreasing its oxidation. ► A tentative pathway for the degradation of naproxen was proposed.α-MnO₂ nanostructures with different morphologies including nanoparticles, flower-like nanostructures and nanorods have been successfully prepared and used in the heterogeneous oxidation of naproxen in water. It has been found out that the heterogeneous oxidation process is highly pH dependent, with higher efficiency at lower pH values. The oxidation kinetics of naproxen were modeled by Langmuir–Hinshelwood equations. Based on the kinetic constants ( k), the oxidation efficiency follows the order of commercial particles−, CO₃²⁻, SO₄²⁻, PO₄³⁻) and cations (Mn²⁺) could remarkably decrease the removal rate by competitively adsorbing and reacting with MnO₂, respectively. In addition, a total of 7 byproducts were identified by LC–MS from which a tentative pathway was proposed.

Keywords: Manganese oxide; Pharmaceutical and personal care products; Naproxen; Heterogeneous oxidation; Nanostructures

A detailed microkinetic model for diesel engine emissions oxidation on platinum based diesel oxidation catalysts (DOC) by Hom Sharma; Ashish Mhadeshwar (pp. 190-204).

Display Omitted► A microkinetic model is developed for diesel engine emissions oxidation on Pt. ► Kinetic parameters are estimated from temperature programmed experiments in literature. ► The mechanism is validated and analyzed against experimental data at practically more relevant conditions.In this work, a comprehensive 124-step (62 reversible) microkinetic model is developed for the oxidation of five major diesel engine emission components (carbon monoxide, nitric oxide, formaldehyde, ammonia, and hydrogen cyanide) on Pt. Kinetic parameters for the detailed microkinetic model are extracted from ultra-high vacuum (UHV) temperature programmed desorption/reaction (TPD/TPR) experiments in literature. Starting with these kinetic parameters as initial estimates, the surface reaction mechanism is extensively tested against practically more relevant operating conditions, such as atmospheric pressure, dilute emissions concentrations, and short residence times, typically experienced by the Diesel Oxidation Catalysts (DOCs). In each of the five oxidation cases, mechanistic analysis is presented to uncover the most important reaction chemistry. The microkinetic model shows very good agreement with multiple experimental data sets on monolith and fixed bed reactor scale, for the oxidation of all five components. For practical implementation, the mechanism is further reduced to 94 steps (47 reversible) using preliminary model reduction.

Keywords: Emissions; Oxidation; Platinum; Microkinetic; Diesel; DOC; Aftertreatment

Nanocrystalline CaSb₂O₅(OH)₂ and Ca₂Sb₂O₇: Controlled syntheses, electronic structures and photocatalytic activity by Renkun Huang; Ximing Xu; Jia Zhu; Wenjun Liu; Rusheng Yuan; Xianzhi Fu; Yongfan Zhang; Zhaohui Li (pp. 205-211).

Display Omitted► pH-dependent controlled syntheses of CaSb₂O₅(OH)₂ and cubic Ca₂Sb₂O₇ with large surface area. ► CaSb₂O₅(OH)₂ and Ca₂Sb₂O₇ show photocatalytic activity for the degradation of MO and benzene. ► CaSb₂O₅(OH)₂ is more photocatalytic active than Ca₂Sb₂O₇ due to its lower crystal packing factor (PF).A facile one-pot pH-dependent hydrothermal method has been developed in the controlled syntheses of CaSb₂O₅(OH)₂ and cubic Ca₂Sb₂O₇ with large specific surface area. The as-obtained samples were characterized by X-ray diffraction (XRD), N₂-sorption BET surface area, UV–vis diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray analysis (EDX) and Fourier transformation infrared spectroscopy (FT-IR). The electronic structures of CaSb₂O₅(OH)₂ and cubic Ca₂Sb₂O₇ were determined by density functional theory (DFT) calculations. The photocatalytic performance of the as-prepared CaSb₂O₅(OH)₂ and cubic Ca₂Sb₂O₇ was evaluated by the degradation of methyl orange (MO) and gaseous benzene. It was found that CaSb₂O₅(OH)₂ is more photocatalytic active than Ca₂Sb₂O₇. A low crystal packing factor (PF) of CaSb₂O₅(OH)₂ is probably responsible for its superior photocatalytic performance as compared to that of cubic Ca₂Sb₂O₇.

Keywords: Hydrothermal; Photocatalysis; Electronic structure; Crystal structure

Selective oxidation of glycerol with oxygen in base-free solution over MWCNTs supported PtSb alloy nanoparticles by Renfeng Nie; Dan Liang; Lian Shen; Jing Gao; Ping Chen; Zhaoyin Hou (pp. 212-220).

Display Omitted► PtSb alloy nanoparticles were prepared on the surface of MWCNTs. ► PtSb alloy nanoparticles are highly active for selective oxidation of glycerol. ► TOF of Pt in PtSb/MWCNTs is 2.6 times of that of Pt/MWCNTs at low glycerol conversion. ► CC cleavage over PtSb alloy is lower than Pt and Pt-Bi/MWCNTs.Multiwall carbon nanotubes (MWCNTs) supported PtSb alloy nanoparticles were prepared and used in the selective oxidation of glycerol to dihydroxyacetone (DIHA) in a base-free aqueous solution. The structure and morphology of the prepared PtSb/MWCNTs catalyst were characterized and compared with that of Pt-Bi/MWCNTs. It was found that Sb homogenously entered into the lattice of Pt and PtSb alloy nanoparticles formed in PtSb/MWCNTs, but Pt particles in Pt-Bi/MWCNTs were wrapped by a layer of Bi₂O₂CO₃. PtSb/MWCNTs is extremely active for the selective oxidation of glycerol to DIHA. The turnover frequency of surface Pt atoms in PtSb/MWCNTs increased from 341.5 (of Pt/MWCNTs) to 878.1h⁻¹. At the same time, DIHA is relatively ‘stable’ over the homogenous PtSb alloy nanoparticles, which also depressed the cleavage of CC.

Keywords: Glycerol oxidation; PtSb alloy, MWCNTs; Base-free; Dihydroxyacetone

Electrochemical decomposition of urea with Ni-based catalysts by Wei Yan; Dan Wang; Gerardine G. Botte (pp. 221-226).

Display Omitted► Ni, Ni-Zn and Ni-Zn-Co catalysts were synthesized by electrodeposition/leaching. ► Ni-Zn and Ni-Zn-Co catalysts enhanced urea electrochemical decomposition. ► Ni-Zn-Co catalysts provide efficiencies above 80% for urea electrolysis.Nickel based catalysts (Ni, Ni-Zn, and Ni-Zn-Co) synthesized through electrodeposition and alkaline leaching processes were used as electrocatalysts for the electrochemical decomposition of urea to benign nitrogen and fuel cell grade hydrogen. The performances of the Ni-based catalysts for the urea decomposition were investigated through cyclic voltammetry (CV) and polarization techniques. The results of the CVs show that the Ni-Zn catalysts and the Ni-Zn-Co catalysts decreased the onset potential of urea oxidation by 40mV and 80mV, respectively when compared to Ni catalysts. The highest efficiency for the oxidation of urea was observed with the Ni-Zn-Co catalysts. The Ni-Zn and Ni-Zn-Co catalysts are promising materials for large-scale urea removal/decomposition from urea-rich wastewater, as well as for hydrogen production.

Keywords: Urea-rich wastewater; Environmental pollutants; Urea removal/decomposition; Ni-Zn and Ni-Zn-Co catalysts; Hydrogen production

Photocatalytic activity of titania layer prepared by oxidizing titanium compounds on titanium plate surface by Hiromasa Nishikiori; Masato Takei; Kyoichi Oki; Syouta Takano; Nobuaki Tanaka; Tsuneo Fujii (pp. 227-233).

Display Omitted► Anatase titania was prepared by oxidizing the crystalline TiN and C-doped TiN phases. ► The crystalline phase was identified by XRD analysis and Raman spectroscopy. ► Anatase phase exhibited a high photocatalytic activity for acetaldehyde degradation. ► The activity was also determined by the crystallite size. ► The activity is due to the thin surface anatase layer accessible to the reactants.Anatase-type nanocrystalline titania layers were prepared by oxidizing the crystalline titanium nitride and carbon-doped titanium nitride phases prepared on a titanium plate surface. Identification of the crystalline phase was confirmed by the XRD patterns and Raman spectra of these plates. The photocatalytic activity of the plates was evaluated by observing the photocalytic degradation process of acetaldehyde gas during UV irradiation by gas chromatography. A relatively larger amount of the anatase phase was formed on the very thin surface layer by heating the carbon-doped titanium nitride phase at 500°C, and it exhibited a higher photocatalytic activity for the acetaldehyde degradation. The activity was determined not only by the amount of the anatase phase, but also by the crystallite size depending on the surface area and charge transfer efficiency. The photocatalytic activity is suggested to be due to the anatase phase existing on the thin surface layer accessible to the reactants.

Keywords: Titania; Photocatalysis; Oxidation; Titanium nitride; Carbon-doped titanium nitride

Influence of cerium modification methods on catalytic performance of Au/mordenite catalysts in CO oxidation by Lei Qi; Changjin Tang; Lei Zhang; Xiaojiang Yao; Yuan Cao; Lichen Liu; Fei Gao; Lin Dong; Yi Chen (pp. 234-245).

Display Omitted► The morphology of cerium species varies with different Ce modification methods. ► Surface acidic property of supports influences the distribution of Au particles. ► The synergetic effect on AuCeO₂ interface is enhanced by facile Ce⁴⁺/Ce³⁺ redox. ► AuCeO₂ interface is better than AuCe n⁺ interface to promote CO oxidation activity.This work investigated influence of cerium modification methods (impregnation and ion-exchange) on the gold dispersion, surface chemical states, synergistic effect between gold and cerium and CO oxidation activity of Au catalysts supported on Ce modified mordenites. The supports and catalysts were characterized by XRF, ICP, XRD, N₂ adsorption–desorption, UV–vis spectroscopy, HRTEM, in situ FT-IR and XPS. In general, Ce-containing Au catalysts were found to be more active in CO oxidation than the Ce-free counterpart, with the impregnation method of cerium modification being more effective than the ion exchange method. The different catalytic performance of Ce-containing catalysts was related to multiple factors: (1) the impregnation method of cerium modification was more favorable to form Au particles with smaller mean size than the ion-exchange method, due to the higher ratio of surface Lewis acid sites; (2) the interface between Au and CeO₂ particles produced by impregnation method was more beneficial for the redox equilibrium of Au⁰+Ce⁴⁺↔Au³⁺+Ce³⁺ to shift to right to form more active Au³⁺ species than the interface between Au particles and Ce cations produced by ion-exchange method, which enhanced the synergistic effect between gold and cerium and the catalytic performance of CO oxidation.

Keywords: Mordenite; Au; Ce modification; Synergistic effect; CO oxidation

Catalytic combustion of chlorobenzene on the Ln modified Co/HMS by Wei Zhao; Jie Cheng; Lina Wang; Jinlong Chu; Jinkui Qu; Yahui Liu; Shaohua Li; Hui Zhang; Jianchong Wang; Zhengping Hao; Tao Qi (pp. 246-254).

Display Omitted► Ln modified Co/HMS was studied by catalytic combustion of chlorobenzene. ► Extra-framework CeO₂ can improved the redox ability of Co/HMS effectively. ► A tentative radical mechanism was proposed.Lanthanide (Ln, including La, Ce and Nd) modified Co/HMS was prepared via two pathways: extra-framework modified post-loading and framework modified direct synthesis. The influence of modified methods, rare earths kind and rare earths loading on the catalytic performance of Co/HMS was studied by the catalytic combustion of chlorobenzene (CB). It was found that the extra-framework Ce modified catalysts show the better catalytic performance than the framework Ln modified ones due to that the forming of CeO₂ is advantaged to obtain the fine Co₃O₄ crystal clusters and the reduction of Ce⁴⁺ ions to Ce³⁺ species probably will promote neighboring reduction of Co species. The suitable extra-framework Ce loading (6%, mass fraction) can effectively ameliorate the redox ability of Co species in the channel of HMS. Since the channel of HMS itself and Co(NO₃)₃·6H₂O aqueous solution both are hydrophilic, the polarity adjusting function of framework Ln to the internal reaction between Co species and support is not great in this case. However, the slightly improved redox ability and weak acidity originated from framework Ln still can do some contribution to the catalytic performance. The electronic structure of Co and Ce is advantageous to the delocalization of π-electrons and the forming of radical species.

Keywords: Chlorobenzene; Catalytic combustion; HMS; Rare earths

Low-temperature selective catalytic reduction of NO with NH₃ over V/ZrO₂ prepared by flame-assisted spray pyrolysis: Structural and catalytic properties by Thirupathi Boningari; Rajesh Koirala; Panagiotis G. Smirniotis (pp. 255-264).

.Display Omitted► Dominant isolated polymeric V oxide species in V/ZrO₂ samples with V/Zr≥0.25. ► Formation of ZrV₂O₇ solid solution due to zirconia migration into V₂O₅ crystallites. ► WO_x established promotional effect, whereas MoO_x showed an inhibition effect. ► In-situ FT-IR results are evident for surface NO₂ species with no apparent N₂O. ► Direct correlation between concentration of the Brönsted acid sites and SCR activity.A series of V/ZrO₂ (V/Zr atomic ratio=0.05, 0.11, 0.17, 0.25, 0.33, 0.42), V-WO_x(0.66)/ZrO₂, and V-MoO_x(0.66)/ZrO₂ were synthesized by adopting a one-step flame spray pyrolysis technique and investigated for the low-temperature selective catalytic reduction (SCR) of NO with ammonia in the presence of excess oxygen. Our XRD results suggest that the vanadia species are in amorphous state as dominant surface monomeric VO_x species on zirconia support in V/ZrO₂ samples with V/Zr≤0.17. Further increase in vanadia content led to the formation of ZrV₂O₇ solid solution as a result of zirconia migration into the V₂O₅ crystallites. H₂-TPR data results are highly consistent with the XRD results that the low temperature shifts in the reduction peaks of 15% V/ZrO₂ catalyst attributed to the presence of more easily reducible dominant surface monomeric VO_x species. The evolution of a new reduction peak at high temperature indicates the formation of dominantly isolated polymeric V oxides species in V/ZrO₂ samples with V/Zr≥0.25. Our H₂-TPR profiles for tungsten-promoted V/ZrO₂ catalyst revealed the shift of ( T₁) peak position to lower temperatures, suggesting that the reduction potential of vanadium oxide species is increased compared to V/ZrO₂ catalyst. This occurrence signifying that the addition of tungsten to V/ZrO₂ promoted the catalyst for the formation of monomeric surface vanadia species, whereas the addition of Mo promoted the formation of polymeric VO_x species and thus inhibit the SCR activity. An intense sharp band characteristic of coordinatively held NO₂ species is evident at 1630cm⁻¹, no gaseous N₂O species were detected at 2224cm⁻¹, 1286cm⁻¹ in the in-situ FT-IR spectra of NO adsorbed over the V/ZrO₂. Our in-situ FT-IR studies of NO+NH₃ co-adsorption demonstrate that the strong signals at 1435 and 1714cm⁻¹ (bending vibration of NH⁴⁺) have seen to decrease with respect to temperature. This observation reveals that the NH⁴⁺ species bound to Brönsted acid sites are responsible for the enhancement in the SCR reaction over the vanadia-zirconia surfaces. The low temperature NO catalytic reduction activity would indicate that an optimal dispersion of monomeric VO_x species on zirconia is attained with the 15% of V in the V/ZrO₂ catalyst. The introduction of Zr (seven fold coordination) into V₂O₅ may lead to the reduction of elemental number in crystal grain and deviation of adjacent oxygen atoms. The change in lattice parameter, crystal anisotropy and negative thermal expansion can block the release of labile oxygen, this seems to be the reason for the decrease in catalytic activity in V/ZrO₂ catalysts with V/Zr≥0.25. The addition of tungsten has a strong influence on the NO conversion, since tungsten loading with the WO_x/VO_x atomic ratio=0.66 exhibits a maximum conversion of ∼98% in the temperature range 180–240°C, whereas the molybdenum loading showed an inhibition effect on the SCR activity of V/ZrO₂ catalyst.

Keywords: Low-temperature NH; ₃; -SCR; Vanadia (VO; _x; ); Zirconia (ZrO; _x; ); NO; Flame spray pyrolysis; In-situ FT-IR

Tungsten carbide on directly grown multiwalled carbon nanotube as a co-catalyst for methanol oxidation by Mansour Rahsepar; Mahmoud Pakshir; Pavel Nikolaev; Afsaneh Safavi; Kowsalya Palanisamy; Hasuck Kim (pp. 265-272).

Display Omitted► Tungsten carbide was synthesized on directly grown MWCNTs as co-catalyst. ► Electrocatalytic performance of the catalysts was studied for methanol oxidation. ► Unique spatial configuration of directly grown MWCNTs was substantially effective. ► Modification of MWCNTs with tungsten carbide enhances the catalyst performance.Multiwalled carbon nanotubes (MWCNT) were grown directly on the surface of graphite rod by using CVD process and then modified with tungsten carbide by carbothermal hydrogen carbonization technique. Then, platinum nanoparticles were deposited on the MWCNTs by means of electrodeposition technique. Catalyst materials were characterized by electron microscopy, X-ray photoelectron spectroscopy and three electrode electrochemical measurements. Catalysts supported on the directly grown MWCNTs exhibit notably better electrocatalytic performance towards methanol oxidation compared to the commercial Pt/C catalyst. Modification of MWCNTs with tungsten carbide was shown to further increase the catalyst performance. It is believed that the superior performance of catalysts prepared on the MWCNTs as catalyst support results mostly from the superior electrical contact and unique spatial configuration of the directly grown MWCNTs, while the positive effect of the tungsten carbide co-catalyst is mostly attributed to its improved resistance towards poisoning with the reaction intermediates produced during the methanol oxidation.

Keywords: Tungsten carbide; Carbon nanotubes; Fuel cell electrocatalysts, Methanol oxidation

Rational direct synthesis methodology of very active and hydrothermally stable Cu-SAPO-34 molecular sieves for the SCR of NO_x by Raquel Martínez-Franco; Manuel Moliner; Cristina Franch; Arkady Kustov; Avelino Corma (pp. 273-280).

Display Omitted► Rational direct synthesis of Cu-SAPO-34 by using the co-directing templates.► Easy control of Cu-loading in Cu-SAPO-34 materials, and very high solid yields.► High activity and stability for SCR of NO_x.A one-pot direct synthesis of Cu-SAPO-34 has been achieved that allows more than 90% yield in the material synthesis. By this method it is easy to control the Cu-loading in the Cu-SAPO-34. It is presented that a maximum in hydrothermal stability with very high activity for NO_x SCR with NH₃ is obtained for an optimum Cu loading.

Keywords: One-pot synthesis; Silicoaluminophosphate; SAPO-34; Selective catalytic reduction (SCR); Nitrogen oxides (NO; _x; )

Catalytic upgrading of biomass pyrolysis vapors using transition metal-modified ZSM-5 zeolite by E.F. Iliopoulou; S.D. Stefanidis; K.G. Kalogiannis; A. Delimitis; A.A. Lappas; K.S. Triantafyllidis (pp. 281-290).

Display Omitted► Ni or Co/ZSM-5 catalysts for the in situ upgrading of biomass pyrolysis vapors. ► Produced bio-oil is enriched in aromatics and phenols and is less oxygenated. ► Reduced metallic Ni and Co species are formed during the pyrolysis reaction. ► Reduced metal phases can favor hydrogen transfer reactions during pyrolysis. ► Enhanced (de)hydrogenation reactions favor production of light alkanes & aromatics.The main objective of the present work was the study of different ZSM-5 catalytic formulations for the in situ upgrading of biomass pyrolysis vapors. An equilibrium, commercial diluted ZSM-5 catalyst was used as the base case, in comparison with a series of nickel (Ni) and cobalt (Co) modified variants at varying metal loading (1–10wt.%). The product yields and the composition of the produced bio-oil were significantly affected by the use of all ZSM-5 catalytic materials, compared to the non-catalytic flash pyrolysis, producing less bio-oil but of better quality. Incorporation of transition metals (Ni or Co) in the commercial equilibrium/diluted ZSM-5 catalyst had an additional effect on the performance of the parent ZSM-5 catalyst, with respect to product yields and bio-oil composition, with the NiO modified catalysts being more reactive towards decreasing the organic phase and increasing the gaseous products, compared to the Co₃O₄ supported catalysts. However, all the metal-modified catalysts exhibited limited reactivity towards water production, while simultaneously enhancing the production of aromatics and phenols. An interesting observation was the in situ reduction of the supported metal oxides during the pyrolysis reaction that eventually led to the formation of metallic Ni and Co species on the catalysts after reaction, which was verified by detailed XRD and HRTEM analysis of the used catalysts. The Co₃O₄ supported ZSM-5 catalysts exhibited also a promising performance in lowering the oxygen content of the organic phase of bio-oil.

Keywords: Lignocellulosic wood biomass; Catalytic biomass flash pyrolysis; Bio-oil; Zeolites; Transition metals; Nickel; Cobalt

Carbon nanofibres as substrates for the preparation of TiO₂ nanostructured photocatalysts by M. Ouzzine; M.A. Lillo-Ródenas; A. Linares-Solano (pp. 291-299).

Display Omitted► TiO₂/CNF hybrids and TiO₂ nanofibres can be obtained using CNFs as substrates. ► CNFs with low-moderate crystallinity permit to get uniform TiO₂ deposition on them. ► Removal of CNFs by burning leads to TiO₂ nanofibres with a central hollow. ► TiO₂/CNF hybrids possess larger photocatalytic activity than TiO₂ nanofibres. ► Oxidation of the CNFs previous to TiO₂ deposition increases photoactivity.Carbon nanofibres from different origins have been used as substrates for the preparation of TiO₂/CNF hybrid materials and TiO₂ nanofibres. The influence of the CNFs on the final properties of the prepared materials is analysed. The results show that the crystallinity of the CNFs used is the parameter that most influences the quality of the TiO₂ deposition. CNFs with low-to-moderate crystallinities are suitable for preparing TiO₂/CNF materials with a uniform TiO₂ coating and with interesting properties: high surface areas, close to 400m²/g, and anatase phase. Additionally, TiO₂ nanofibres maintaining such anatase phase and an important surface area can be prepared from these uniform TiO₂/CNF hybrids by burning the CNFs. These TiO₂/CNF hybrid materials and TiO₂ nanofibres, having larger surface areas than similar materials prepared in a previous work using carbon nanotubes, are analysed as photocatalysts for the oxidation of propene at low concentration (100ppmv) under UV light irradiation. The results show interesting photocatalytic activities (better for the hybrid materials than for the TiO₂ nanofibres), that can be further enhanced increasing the surface area and/or reaching a suitable anatase/rutile proportion.

Keywords: Titanium dioxide; Carbon nanofibres; Photocatalytic activity; Propene

Templated non-PGM cathode catalysts derived from iron and poly(ethyleneimine) precursors by Alexey Serov; Michael H. Robson; Kateryna Artyushkova; Plamen Atanassov (pp. 300-306).

Display Omitted► First report on templating a high-molecular weight precursor for non-PGM catalysts. ► Most critical parameters are the metal/nitrogen ratio and pyrolysis temperature. ► The role of the transition metal in oxygen reduction mechanism is discussed.A series of oxygen reduction catalysts derived from pyrolyzed iron-containing compounds and a nitrogen-containing polymeric precursor, poly(ethyleneimine), (Fe–PEI) were prepared using a sacrificial support method (SSM). The synthesis includes high-temperature pyrolysis in inert atmosphere of the precursor that has been deposited onto a highly dispersed silica support, followed by etching (dissolving) the oxide support, thus resulting in a templated, self-supported, highly porous material – the non-PGM electrocatalyst. The influence of experimental parameters on the catalytic activity of the oxygen reduction reaction (ORR) in acid media was studied, such as molecular weight of PEI, temperature of the heat treatment, duration of the heat treatment, and the ratio of metal to nitrogen precursor. This series of materials was analyzed and characterized by scanning electron microscopy (SEM), BET method (BET) and XPS in order to establish structural morphology and chemical moieties, which was then correlated to activity. Rotating ring disk electrode (RRDE) experiments were performed to evaluate catalytic activity, and the ring current data was used to conduct a mechanistic study of the material for the ORR. This work has determined that the most influential parameters on activity are the metal to nitrogen precursor ratio, and temperature of the heat treatment. Accelerated durability RDE tests (cycling between 0.2 and 1.1V) revealed high stability of synthesized materials in acid media.

Keywords: Non-PGM catalysts; Fuel cell; ORR; Cathode

Effect of precursor on the performance of alumina for the dehydration of methanol to dimethyl ether by Ahmed I. Osman; Jehad K. Abu-Dahrieh; David W. Rooney; Samih A. Halawy; Mohamed A. Mohamed; Adel Abdelkader (pp. 307-315).

Display Omitted► Effect of precursors on the catalytic performance of alumina. ► AN samples are higher activity than AC, while AN550 is the optimum one. ► The AN550 showed methanol conversion and DME selectivity of 72% and 100% at 250°C, respectively. ► Acid site density affected catalytic performance among the catalysts with alumina phase. ► Synthesis of alumina catalyst with high activity compared to commercial γ-Al₂O₃.Dimethyl ether (DME) is amongst one of the most promising alternative, renewable and clean fuels being considered as a future energy carrier. In this study, the comparative catalytic performance of γ-Al₂O₃ prepared from two common precursors (aluminum nitrate (AN) and aluminum chloride (AC)) is presented. The impact of calcination temperature was evaluated in order to optimize both the precursor and pre-treatment conditions for the production of DME from methanol in a fixed bed reactor. The catalysts were characterized by TGA, XRD, BET and TPD-pyridine. Under reaction conditions where the temperature ranged from 180°C to 300°C with a WHSV=12.1h⁻¹ it was found that all the catalysts prepared from AN(η-Al₂O₃) showed higher activity, at all calcination temperatures, than those prepared from AC(γ-Al₂O₃). In this study the optimum catalyst was produced from AN and calcined at 550°C. This catalyst showed a high degree of stability and had double the activity of the commercial γ-Al₂O₃ or 87% of the activity of commercial ZSM-5(80) at 250°C.

Keywords: DME; Methanol dehydration; Acid catalyst; η-Al; ₂; O; ₃; γ-Al; ₂; O; ₃

A comparative study of photocatalytic degradation of 3-chloropyridine under UV and solar light by homogeneous (photo-Fenton) and heterogeneous (TiO₂) photocatalysis by M.C. Ortega-Liébana; E. Sánchez-López; J. Hidalgo-Carrillo; A. Marinas; J.M. Marinas; F.J. Urbano (pp. 316-322).

Display Omitted► Photo-Fenton process is ca. 5 times faster than TiO₂ photocatalysis. ► Complete mineralization using sun light and results at lab-scale well extrapolated to larger scale. ► Some intermediates more toxic than 3-chloropyridine formed as the reaction proceeds. ► Photo-Fenton process quite sensitive to the presence of phosphate.Photocatalytic degradation of 3-chloropyridine in the homogeneous (photo-Fenton) and heterogeneous (TiO₂) phase was studied using both UV and sun light. Complete mineralization was achieved in both cases though times required in photo-Fenton process were ca. 5 times shorter under our experimental conditions. Results found at lab scale (solar simulator) were successfully extrapolated to a larger scale (30L) thus evidencing the validity of the method for treatment of waters polluted with this kind of chemical. Toxicity tests ( Vibrio fischeri) showed that some intermediates more toxic than 3-chloropyridine were formed as reaction proceeded.

Keywords: Photocatalysis; Photo-Fenton; TiO; ₂; Chloropyridines

Ethanol-selective catalytic reduction of NO by Ag/Al₂O₃ catalysts: Activity and deactivation by alkali salts by Leonhard Schill; Siva Sankar Reddy Putluru; Casper Funk Jacobsen; Christian Houmann Hansen; Rasmus Fehrmann; Anker Degn Jensen (pp. 323-329).

Display Omitted► Ag/Al₂O₃ catalysts are highly active in hydrocarbon SCR and CO₂ selective. ► Ag catalysts exhibited higher resistance to alkali salts than commercial V-based catalysts. ► 500ppm of H₂ promotes slightly and 25ppm of SO₂ severely deactivates the SCR activity.Ag/Al₂O₃ catalysts with and without potassium doping were prepared by incipient wetness impregnation and characterized by N₂ physisorption, XRPD, NH₃-TPD and SEM. The influence of the Ag content from 1 to 5wt.% was investigated for the selective catalytic reduction (SCR) of NO with ethanol. The 3wt.% Ag/Al₂O₃ catalyst was found to be the most active and CO₂ selective over a wide temperature window (300–500°C). Addition of 500ppm of H₂ has a mild promotional effect on the activity while SO₂ has a strong negative influence on the SCR activity. Furthermore, the Ag/Al₂O₃ ethanol-SCR catalyst deactivated significantly by the addition of potassium although it was more resistant than the conventional V₂O₅ based NH₃-SCR catalyst, which deactivated more at lower potassium loading. The higher potassium resistivity of the Ag/Al₂O₃ catalysts seems to be due to differences in reaction mechanism of Ag/Al₂O₃ ethanol-SCR catalyst compared to the conventional NH₃-SCR catalyst. The still low potassium resistance, in combination with the high sensitivity to SO₂, seems not to make these catalysts a real option for biomass fired boilers.

Keywords: SCR of NO with ethanol; Ag/Al; ₂; O; ₃; Potassium poisoning

Excellent performance of mesoporous Co₃O₄/MnO₂ nanoparticles in heterogeneous activation of peroxymonosulfate for phenol degradation in aqueous solutions by Hanwen Liang; Hongqi Sun; Archana Patel; Pradeep Shukla; Z.H. Zhu; Shaobin Wang (pp. 330-335).

Display Omitted► Mesoporous MnO₂ exhibited activity in peroxymonosulfate (PMS) activation. ► Co/MnO₂ nanoparticles presented better performance than Co²⁺/PMS in phenol degradation. ► Phenol degradation on Co/MnO₂ followed first order kinetics.Mesoporous α-MnO₂ and its supported Co₃O₄ nanoparticles were synthesized, characterized and tested in heterogeneous activation of peroxymonosulfate (PMS) for phenol degradation in aqueous solution. α-MnO₂ supported Co₃O₄ presented as nanorod particles and showed H₂ redox reduction at low temperature. Bulk α-MnO₂ and Co₃O₄ could activate peroxymonosulfate to generate sulfate radicals for phenol degradation but at low activity. Co₃O₄/MnO₂ nanoparticles exhibited much high activity in peroxymonosulfate activation for phenol degradation with 100% conversion in 20min and 3wt% is the optimum Co loading. Phenol degradation followed a first order kinetics. Stability tests also showed that Co₃O₄/MnO₂ presented stable performance in phenol degradation in several runs.

Keywords: Mesoporous MnO; ₂; Supported Co oxide; Advanced oxidation; Water treatment; Nanorod particles

Ce-doped strontium cobalt ferrite perovskites as cathode catalysts for solid oxide fuel cells: Effect of dopant concentration by Hyunkyu Choi; Anshuman Fuller; Jonathan Davis; Christopher Wielgus; Umit S. Ozkan (pp. 336-341).

Display Omitted► The ORR activity of cerium-doped SrCo(Fe)O₃ perovskites was investigated. ► CeO₂ was seen to segregate when the amount of cerium doped exceeded 15% in the A-site. ► Desorption and intra-facial transport of oxygen were studied by O₂-TPD and CO₂-TPO. ► SrCo(Fe)O₃ perovskites doped with Intermediate levels of cerium show potential as SOFC cathodes.The bulk structure, oxygen mobility, and button cell performance of perovskite-type oxides with the formula Sr1−_xCe_xCo_0.2Fe_0.8O3−_δ for x=0.10, 0.15, and 0.20 have been investigated using in situ X-ray diffraction (XRD), oxygen temperature-programmed desorption (O₂-TPD), CO₂-temperature-programmed oxidation (TPO) and button cell/impedance measurements. XRD results indicate that cerium-doped perovskites have a cubic structure and do not undergo structural changes with increasing temperature. An additional CeO₂ phase was observed when the concentration of Ce exceeded 15%. Addition of cerium lowers the thermal expansion coefficient (TEC), bringing the TEC closer to that of gadolinia-doped ceria (GDC) electrolyte. The oxygen vacancy generation was inversely proportional to the doping concentration of Ce. However, the best unit cell performance and the lowest impedance were achieved with intermediate levels of Ce doping, suggesting that the ceria phase which segregates at higher doping levels has a detrimental effect on the cell performance. CO₂-TPO experiments which were used to examine the rate of intra-facial transport of oxygen were found to be a good probe for button cell performance.

Keywords: SOFC; Perovskite; O; ₂; -TPD; CO; ₂; -TPO; Impedance; Cathode; Oxygen reduction

Silica-encapsulated platinum catalysts for the low-temperature water-gas shift reaction by Yuan Wang; Yanping Zhai; Danny Pierre; Maria Flytzani-Stephanopoulos (pp. 342-350).

.Display Omitted► Encapsulated platinum in the form of core–shell Pt@SiO₂ was prepared by reverse microemulsion method. ► With alkali ion addition, Pt-Na@SiO₂ or Na(IMP)-Pt@SiO₂ are active catalysts for the low-temperature water-gas shift (WGS) reaction. ► The active Pt–O_x(OH)–Na species in the silica shell stabilize both the Pt and Na ions; dissociate water and regenerate surface hydroxyl groups. ► The apparent activation energy for the WGS reaction over Pt-based catalysts is independent of the support structure and type.Encapsulated platinum in the form of core–shell Pt@SiO₂ prepared by reverse microemulsion, can be rendered catalytically active for the low-temperature water-gas shift (WGS) reaction by the addition of alkali ions during the synthesis steps or by impregnation of the dried (uncalcined) core–shell materials. We report that positively charged platinum species, embedded throughout the silica shell and stabilized by the alkali ions are the active sites for the WGS reaction. Water dissociation and hydroxyl regeneration take place on the Na-promoted Pt–O_x sites. It is shown by cyclic CO-TPR experiments with intermittent ambient rehydration that the activity remains constant, and the onset temperature of the reaction is the same, ∼150°C, with cycling. The apparent activation energies for the WGS reaction in realistic fuel gas mixtures over the various encapsulated Pt-based catalysts evaluated here and those on other supports are all in the same range, 70±5kJ/mol. Hence any difference in the reaction rates between the open- and encapsulated-Pt catalysts is attributed to their different number of active sites accessible to the reactants. The Pt-Na@SiO₂ catalyst structures show remarkable stability with time-on-stream at 350°C.

Keywords: Pt catalysts; Encapsulation; Reverse microemulsion; Water-gas shift reaction; Alkali promotion

Pt–Ag/activated carbon catalysts for water denitration in a continuous reactor: Incidence of the metal loading, Pt/Ag atomic ratio and Pt metal precursor by A. Aristizábal; S. Contreras; N.J. Divins; J. Llorca; F. Medina (pp. 351-362).

Display Omitted► Pt–Ag/AC are active and stable catalysts for water denitration in a continuous PBR. ► Pt precursor and metal loading are the most relevant variables in this process. ► Activity and selectivity are affected by changes in the active sites architecture. ► Higher nitrate conversion and nitrogen selectivity are obtained using H₂PtCl₆. ► To maximize conversion a ratio 1.1 and 3%Pt content are recommended.Several Pt–Ag catalysts supported on activated carbon powder were tested in the catalytic reduction of nitrates in a continuous flow reactor. The influence of the noble metal precursor (Pt(NH₃)₄(NO₃)₂ or H₂PtCl₆), the Pt/Ag atomic ratio (0.3, 1.1 and 1.8) and the metal loading (3% or 1% Pt) were studied. The samples were characterized by XRD, TPR, HRTEM, XPS, H₂-chemisorption and nitrogen physisorption. The results showed that the most important variables affecting the catalytic activity are the noble metal precursor and the metal loading, whereas the Pt/Ag atomic ratio does not affect significantly the catalytic behavior. The use of H₂PtCl₆ instead of Pt(NH₃)₄(NO₃)₂ as noble metal precursor leads to more active catalysts. The nitrate conversion is enhanced by the high metal loading (3%).

Keywords: Pt–Ag; Catalytic nitrates reduction; Metal content; Packed bed reactor; Surface metal chemistry

Highly efficient photocatalytic oxidation of sulfur-containing organic compounds and dyes on TiO₂ with dual cocatalysts Pt and RuO₂ by Feng Lin; Yongna Zhang; Lu Wang; Yuliang Zhang; Donge Wang; Min Yang; Jinhui Yang; Boyu Zhang; Zongxuan Jiang; Can Li (pp. 363-370).

Display Omitted► Highly efficient photocatalytic oxidation of pollutants was achieved on TiO₂ co-loaded with Pt and RuO₂. ► The co-loaded reduction cocatalyst and oxidation cocatalyst shows considerably synergistic effect. ► The active oxygen species are involved in the photocatalytic oxidation of the pollutants.Photocatalytic oxidation has been demonstrated to be an effective way for removing organic pollutants via a complete mineralization. The removal of sulfur-containing organic compounds in fuel oils and pollutants such as rhodamine B (RhB) and methyl orange (MO) present in the industrial wastewater is highly desired. Here we studied the photocatalytic oxidation of the pollutants on Pt–RuO₂/TiO₂ photocatalyst. We found that TiO₂ co-loaded with noble metal Pt and metal oxide RuO₂ shows the considerably synergistic effect between the two cocatalysts on photocatalytic oxidation activity. This effect has been demonstrated for photocatalytic oxidation of thiophene and successfully extended to photocatalytic oxidation of organic dyes. The high activity is achieved by co-loading less than 0.05wt% Pt and 0.05wt% RuO₂ as cocatalysts on TiO₂. ESR measurements give the evidence for that the active oxygen species (OH and O₂⁻) generated by photocatalytic processes are involved in photocatalytic oxidation reactions. The reduction cocatalyst Pt and oxidation cocatalyst RuO₂ play significant roles in the photocatalytic oxidation reaction and the co-existing of the dual function cocatalysts is crucial for developing highly active photocatalysts for environmental protection.

Keywords: Dual cocatalysts; Sulfur-containing organic compounds; Dyes; Photocatalytic oxidation; Pt–RuO; ₂; /TiO; ₂

Low and non-platinum electrocatalysts for PEMFCs: Current status, challenges and prospects by A. Brouzgou; S.Q. Song; P. Tsiakaras (pp. 371-388).

Display Omitted► The highest reported mass specific power density value for H₂-PEMFCs has far exceeded the 2015 target(5mWμgPttotal−1). ► A several number of investigations reported values1–5mWμgPttotal−1 for a H₂-PEMFCs. ► The highest mass specific power density for DMFCs was ca.0.15mWμgPttotal−1. ► The highest mass specific power density for DEFCs was ca.0.05mWμgPttotal−1. ► Design and testing of novel non-Pt anodes and cathodes in fuel cells is increasing.Platinum-based nanomaterials are the most commonly adopted electrocatalysts for both anode and cathode reactions in polymer electrolyte membrane fuel cells (PEMFCs) fed with hydrogen or low molecular alcohols. However, the scarce world reserves of Pt and its high price increases the total cost of the system and thus limits the feasibility of PEMFCs. Based on this problem, for PEMFCs to have wide practical applications and become commercially viable, the challenging issue of the high catalyst cost resulting from the exclusive adoption of Pt or Pt-based catalysts should be addressed. One of the targets of the scientific community is to reduce the Pt loading in membrane electrode assemblies (MEAs) to ca.150μgcmMEA−2, simultaneously maintaining high PEMFCs performances. The present paper aims at providing the state-of-the-art of low Pt and non-Pt electrocatalysts for: (a) H₂ -O₂ PEMFCs, (b) Direct Methanol Fuel Cells ( DMFCs) and (c) Direct Ethanol Fuel Cells ( DEFCs). The detailed analysis of a big number of recent investigations has shown that the highest mass specific power density (MSPD) value obtained for H₂ -O₂ PEMFCs has far exceeded the 2015 target (5mWμgPttotal-1) set by the USA department of energy, while a several number of investigations reported values between 1 and 5mWμg_Pt⁻¹. However, the highest values measured under DMFCs and DEFCs working conditions are still relatively low and close to 0.15 and 0.05mWμg_Pt⁻¹ respectively. Moreover, the last years, promising results have been reported concerning the design, fabrication, characterization, and testing of novel non-Pt (Pt-free) anodes and cathodes for PEMFCs applications.

Keywords: Low Pt loading electrocatalysts; Non-Pt electrocatalysts; H; ₂; -PEMFCs; DMFCs; DEFCs

CO_x free hydrogen production over cobalt incorporated silicate structured mesoporous catalysts by Dilek Varisli; Nalan G. Kaykac (pp. 389-398).

.Display Omitted► Synthesis solution pH had significant effects on the structure of the final product. ► KOH greatly enhanced the incorporation of cobalt into the mesoporous lattice of amorphous silica. ► Catalysts prepared with KOH promoter gave the highest activity with 70% conversion at 600°C. ► Ammonia conversion was increased by increasing the space velocity over the same catalyst. ► The texture and porosity of SiO₂ is associated to the availability of Co species that affect activity.On board hydrogen production for fuel-cell derived motor vehicles requires resources for CO_x free hydrogen production. Ammonia is one of the most attractive hydrogen storage compounds which may yield clean hydrogen through catalytic decomposition. In the present study, new cobalt incorporated mesoporous silicate catalysts were prepared for ammonia decomposition, by applying a one-pot hydrothermal synthesis procedure. Ammonia decomposition experiments were performed in a fixed bed flow reactor in a temperature range of 400–750°C. While all of the synthesized catalysts showed good activity in hydrogen production from ammonia at temperatures higher than 500°C and at a space velocity of 150,000h⁻¹, catalysts prepared with KOH promoter gave the highest activity with 70% conversion at 600°C and close to total conversion at 700°C. Reduction temperature and period of the synthesized catalysts were also shown to be highly effective on the catalytic performance of the synthesized materials.

Keywords: Hydrogen; Ammonia decomposition; Cobalt; Catalyst; Mesoporous silicate; Hydrothermal synthesis

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Applied Catalysis B, Environmental (v.127, #)