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Peroxymonosulfate (PMS) as an oxidant has been extensively applied to remove organic pollutants, but the molecular interaction mechanism of PMS and organic pollutants under the electrochemical process remains unclear. This work unraveled the interaction relationship of PMS on ofloxacin (OFN) degradation by PMS-based electrochemical oxidation. The results showed that hydroxyl and sulfate radicals generated from the electrochemical reaction could effectively degrade OFN. Under the electrochemical oxidation process, 100% or 12.1 ± 2.1% of OFN was degraded within 15 min in the presence or absence of PMS, respectively. Quantum chemical calculations and molecular dynamics simulations indicated that the hydrogen bonds and van der Waals force were the primary interaction force between PMS and OFN. Besides, the PMS-OFN binding process was a stable dynamic process, and its stability was dependent on the number of hydrogen bonds generated. The structure-activity relationship suggested that OFN was transformed into short-chain intermediates with lower toxicity within 15 min. Additionally, this electrochemical system for degrading OFN retained excellent reusability and recyclability, affording high oxidation ability during successive cycles. More importantly, this electrochemical process could highly efficiently degrade various organic pollutants (4-chlorophenol, methyl orange, sulfamethoxazole, and perfluorooctanoic acid). This study provided a new possibility for the application of the electrochemical system in large-scale wastewater treatment. © 2024 American Chemical Society.

A wide amount of existing building materials and consumables contains formaldehyde (HCHO) that may be released as a gas even after installation. The produced gas may concentrate in housing and offices, leading to a long-term exposure of the occupants. Living in such an environment, even at low concentrations less than 0.5 ppm, may lead to carcinogenic effects and damages of the human central nervous system. As a consequence, the development of methods that oxidize and neutralize the formaldehyde at ambient temperature is welcome. The catalytic oxidation method at ambient temperature is preferred over other available techniques due to its ease of operation and high efficiency. In this work, different weight percentages, ranging from 1 up to 5%, of silver-doped manganese oxides (Ag/MnOx) were synthesized by a co-precipitation process followed by a calcination at 450 °C for 4 h. The XRD and BET analysis results show that the sample at 4% wt of Ag doped in the MnOx matrix exhibit highest crystallinity, surface area and highest dispersion values, very near to theoretical ones. The removal performance of HCHO was tested in a silicon wool bed continuous flow reactor characterized by an inner diameter of 4 mm and a length of 12.5 cm. At ambient temperature a removal efficiency and an amount of produced CO2 of 94% and 66%, respectively., ChemE/Catalysis Engineering

Bulky tri-isopropyl silyl (TIPS) substituents and deuterium atoms in the ligand design have been shown to enhance the site-selective oxidation of aliphatic C−H bonds and the epoxidation of C=C bonds in non-heme iron oxidation catalysis. In this work, a series of non-heme iron complexes were developed by combining TIPS groups and deuterium atoms in the ligand. These bulky deuterated complexes show a significant increase in catalytic performance compared to their counterparts containing only TIPS groups or deuterium atoms. A broad range of substrates was oxidized with excellent yields, particularly, using [Fe(OTf)2((S,S)-TIPSBPBP-D4)] (1-TIPS-D4) (0.1 mol % to 1 mol %) via a fast or slow oxidant addition protocol, resulting in an overall improvement in catalytic performance. Notably, in the oxidation of the complex substrate trans-androsterone acetate, the use of a slow addition protocol and a lower catalyst loading of 1-TIPS-D4 resulted in significant increases in reaction efficiency. In addition, kinetic and catalytic studies showed that deuteration does not affect the catalytic activity and the secondary C−H site-selectivity but increases the catalysts’ lifetime resulting in higher conversion/yield. Accordingly, the yield of selectively oxidized secondary C−H products also increases with the overall yield by using the bulky deuterated iron complexes as catalysts. These catalytic improvements of the bulky deuterated complexes exemplify the enhanced design of ligands for homogeneous oxidation catalysis.

The application-attractive form of TiO₂, CeO₂ and CuO-based open-cell foam supported catalysts was designed to investigate their catalytic performance in oxidation of two model volatile organic compounds—methanol and dichloromethane. TiO₂-CeO₂, TiO₂-CuO and TiO₂-CeO₂-CuO catalysts as thin films were deposited on VUKOPOR®A ceramic foam using a reverse micelles-controlled sol-gel method, dip-coating and calcination. Three prepared catalytic foams were investigated via light-off tests in methanol and dichloromethane oxidation in the temperature range of 45–400 °C and 100–500 °C, respectively, at GHSV of 11, 600 h⁻¹, which fits to semi-pilot/industrial conditions. TiO₂-CuO@VUKOPOR®A foam showed the best catalytic activity and CO₂ yield in methanol oxidation due to its low weak Lewis acidity, high weak basicity and easily reducible CuO species and proved good catalytic stability within 20 h test. TiO₂-CeO₂-CuO@VUKOPOR®A foam was the best in dichloromethane oxidation. Despite of its lower catalytic activity compared to TiO₂-CeO₂@VUKOPOR®A foam, its highly-reducible -O-Cu-Ce-O- active surface sites led to the highest CO₂2 yield and the highest weak Lewis acidity contributed to the highest HCl yield. This foam also showed the lowest amount of chlorine deposits.

In this paper, a novel application of industrial waste, namely red mud (RM), in the abatement of two malodorous and harmful sulfur compounds, dimethyl disulfide (DMDS) and methyl mercaptan (MM), is presented. The effects of calcination and activations with hydrochloric acid or a mixture of hydrochloric and orthophosphoric acid on the properties and performance of RM are compared using laboratory-scale experiments. The RM-based materials were characterized by XRF, XRD, FE-SEM, N₂-physisorption, TGA/DTA, and FTIR analyses. RM exhibits very promising catalytic properties in the abatement of both DMDS and MM. The hydrochloric acid-activated RM was the most active in both cases, which was explained by its rather high specific surface area (144 m² g⁻¹), higher contents of Fe₂O₃ and TiO₂, as well as lower content of phosphorus. For both DMDS and MM, the main oxidation products were sulfur dioxide, carbon monoxide, and carbon dioxide. DMDS was observed as a reaction intermediate in MM oxidation. While the final conversions of DMDS and MM were high, the oxidation was not complete, indicated by the formation of carbon monoxide. Nevertheless, the modified RM appears as a very interesting alternative to the existing DMDS and MM abatement catalysts.

Structured Co3O4 catalysts with a hollow nanotube morphology were prepared by several synthesis routes based on the Kirkendall effect. The resulting samples were kinetically evaluated in the gas-phase oxidation of vinyl chloride and 1,2-dichloroethane, two model C2-chlorinated volatile organic compounds; and exhaustively characterised by means of BET measurements, X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, thermogravimetry and temperature-programmed techniques (adsorption of ammonia and chlorinated VOC, O2-TPD, H2-TPR and TPO). The performance of the prepared nanotubes was essentially controlled by the presence of active oxygen species at the surface, which in turn depended on the Co2+/Co3+ molar ratio, and the adsorption capacity of the catalyst for the chlorocarbon. Both pollutants were efficiently converted to deep oxidation products at relatively low temperatures. In addition, the optimal catalyst exhibited an appreciable stability when operating during 120 h.

Co3O4 catalysts modified with SrCO3 with various Sr:Co molar ratios were synthesized by a co-precipitation method and their catalytic behavior was examined for the gas-phase oxidation of vinyl chloride. The physicalchemical properties of the samples were thoroughly characterized by means of ICP-AES, BET measurements, XRD, H2-TPR, XPS and SEM-EDX. The obtained results revealed that the incorporation of strontium carbonate introduced changes in the textural and structural properties as well as modifications in the surface chemical composition of the catalysts. The performance of the samples was found to be controlled by the concentration of active species on the surface (Co2+/Co3+ and Oads/Olatt ratios) and the reducibility of the samples. As for the stability of the catalysts, clear evidences of deactivation (more severe when increasing the SrCO3 content) were noticed, probably caused by the decomposition of the SrCO3 phase and the formation of SrCl2 accompanied by a loss of textural properties and active surface oxygen species.

Membrane separation and sulfate radicals-based advanced oxidation processes (SR-AOPs) can be combined as an efficient technique for the elimination of organic pollutants. The immobilization of metal oxide catalysts on ceramic membranes can enrich the membrane separation technology with catalytic oxidation avoiding recovering suspended catalysts. Herein, nanostructured Co3O4 ceramic catalytic membranes with different Co loadings were fabricated via a simple ball-milling and calcination process. Uniform distribution of Co3O4 nanoparticles in the membrane provided sufficient active sites for catalytic oxidation of 4-hydroxybenzoic acid (HBA). Mechanistic studies were conducted to determine the reactive radicals and showed that both SO4•− and •OH were present in the catalytic process while SO4•− plays the dominant role. The anti-fouling performance of the composite Co@Al2O3 membranes was also evaluated, showing that a great flux recovery was achieved with the addition of PMS for the fouling caused by humic acid (HA).

Anatase-TiO2-supported Pt (Pt/TiO2(A)) is a well-known supported catalyst for catalyzing the oxidation of formaldehyde (HCHO). However, rutile TiO2 (TiO2(R)) has not been widely utilized for this reaction due to its inferior performance. In this study, we have developed a novel approach involving NaBH4-induced oxygen vacancy manipulation to regulate the valence states of Pt on TiO2(R). By employing a large excess of NaBH4 (nNaBH4/nPt = 2000), we were able to generate an extraordinary concentration of oxygen defects and electron-rich sites on the surface of TiO2(R), resulting in the concentration of Pt0 on Pt/TiO2(R)− 2000 exceeding that on Pt/TiO2(A)− 2000. The newly synthesized Pt/TiO2(R)− 2000 catalyst exhibited a remarkably high turnover frequency (TOF) of 160.2 h−1, which is approximately five times that of Pt/TiO2(R)− 20. The discrepancy in the reaction mechanisms between rutile and anatase was identified as the critical factor underlying the vastly different performances observed.

In this work, the bimetallic iron oxide self-supported electrode was prepared by a simple solvothermal as well as thermal method. CoFeO magnetic nanoparticles were grown in situ on the CFP surface and characterized to reveal the morphology, composition, and electrochemical properties of the electrode. Compared to CFP and CFP@Co-Fe, CFP@CoFeO equipped more efficient mineralization current efficiency and lower energy consumption due to the improved electrocatalytic capacity of CoFeO properly grown on the conductive substrate surface. Further studies showed that the manufactured electrode maintained a high level of stability after continuous operation. According to the free radical trapping experiment, EPR, and liquid mass spectrometry analysis, the rational reaction mechanism of p-nitrophenol was finally proposed, in which ·OH and SO· were considered as the main active oxidants. This work demonstrated the great potential of establishing an electro-Fenton system based on CoFeO immobilized self-supporting cathode for environmental remediation.

Understanding interaction between active sites in heterogeneous catalysis is a grand challenge owing to difficulty in extracting information from different active sites. We report a solution to this problem by showing that electron conduction can facilitate direct interplay of distant active sites. By fabricating two single-atom site catalysts (manganese dioxide-encapsulated metallic silver atomic wires) with one or two ending silver atoms of each wire exposed on surfaces, we find that only the catalyst with both ending silver atoms exposed can trigger low-temperature carbon monoxide oxidation, which provides unequivocal evidence that interaction between active sites is possible upon eligible electron conducting. This result indicates that the interaction between active sites might be universally present in catalysis reactions when there is effective communication between the active sites.

Curved crystals are a simple but powerful approach to bridge the gap between single crystal surfaces and nanoparticle catalysts, by allowing a rational assessment of the role of active step sites in gas-surface reactions. Using a curved Rh(111) crystal, here, we investigate the effect of A-type (square geometry) and B-type (triangular geometry) atomic packing of steps on the catalytic CO oxidation on Rh at millibar pressures. Imaging the crystal during reaction ignition with laser-induced CO2 fluorescence demonstrates a two-step process, where B-steps ignite at lower temperature than A-steps. Such fundamental dissimilarity is explained in ambient pressure X-ray photoemission (AP-XPS) experiments, which reveal partial CO desorption and oxygen buildup only at B-steps. AP-XPS also proves that A-B step asymmetries extend to the active stage: at A-steps, low-active O-Rh-O trilayers buildup immediately after ignition, while highly active chemisorbed O is the dominant species on B-type steps. We conclude that B-steps are more efficient than A-steps for the CO oxidation.

V rámci této disertační práce byla provedena rešerše na téma frustrované Lewisovy páry (FLP) a jejich využití při aktivaci malých molekul. V rešerši je popsána většina publikovaných FLP od roku 2006, kdy byl tento koncept popsán prof. Stephanem. Nejpoužívanější kombinací pro FLP jsou atomy fosforu jako LB a boru jako LK. V posledních letech se však ukazuje, že pro přípravu FLP mohou být použity i jiné nepřechodné prvky 13. a 15. skupiny nebo i prvky 14. a 16. skupiny., In the framework of this thesis, a research was conducted on the topic of Frustrated Lewis pairs (FLP) and their use in the activation of small molecules. This work describes most of the published FLPs since 2006, when this concept was described by prof. Stephan. The most commonly used combinations for FLP are phosphorus atoms such as LB and boron atoms such as LA. In recent years, however, it has been shown that other non-transition elements of groups 13 and 15 or even elements of groups 14 and 16 can be used for the preparation of FLP., Fakulta chemicko-technologická, Dokončená práce s úspěšnou obhajobou

Since the inception of urbanization and industrialization, emissions of volatile organic compounds (VOCs) have become serious concern due to harmful effects on terrestrial biota, serious measures must be taken to minimize the emissions of VOCs. Catalytic oxidation is considered one of the most promising technologies for removing VOCs for its low ignition temperature, high efficiency, and no secondary pollution in the process of treatment.This review summarizes progress made in the catalytic oxidation of VOCs over last ten years. We have dis-cussed the mechanism and current advancement of non-noble metal catalysts to remove VOCs. Besides, the characteristics and the factors affecting catalytic performance of non-noble metal catalysts are comprehensively explained. The critical factors that affect the catalytic performance of catalysts mainly include preparation methods, modification technologies, and carrier materials. Therefore, future research should focus on developing efficient catalysts and performance improvement. We believe that current review will provide a great foundation and reference point for future design and development in this field.

[EN] Mixed metal oxides, of the type (KNaM)xP0.11WV0.2NbOx and (NH4)x/(Na)xP0.11WV0.2NbOx, were prepared by hydrothermal synthesis from lacunary heteropolytungstates, [M4(H2O)2(PW9O34)2]10- (MPW9, with M(II) = Co, Cu or Mn) and their precursor Na8H(PW9O34) (NaPW9), chemically modified by Nb(V) and V(IV). For comparison mixed metal oxides were also synthesized by using a Keggin heteropolytungstates [PW12O40]3- as tungsten precursor. The pristine samples were finally heat-treated at 500 degrees C in flowing N2 for 2 h. The resulting mixed metal oxides were characterized by several physico-chemical techniques and tested in both the liquid phase catalytic oxidation of diphenyl sulfide (DPS), in friendly environmental conditions (using tert-butyl hydroperoxide as oxidant), and in the gas phase partial oxidation of hydrogen sulfide to sulfur (using air at oxidant). Although the catalytic behavior of these catalysts strongly depends on the composition of catalysts, high activity and selectivity have been achieved over mixed metal oxides in both reactions. The good catalytic performance of species containing Cu(II) was evidenced in both reactions studied and the reactivity of this element could be explained by its structural and vibrational spectroscopic properties.

[EN] Mixed metal oxides, of the type (KNaM)xP0.11WV0.2NbOx and (NH4)x/(Na)xP0.11WV0.2NbOx, were prepared by hydrothermal synthesis from lacunary heteropolytungstates, [M4(H2O)2(PW9O34)2]10- (MPW9, with M(II) = Co, Cu or Mn) and their precursor Na8H(PW9O34) (NaPW9), chemically modified by Nb(V) and V(IV). For comparison mixed metal oxides were also synthesized by using a Keggin heteropolytungstates [PW12O40]3- as tungsten precursor. The pristine samples were finally heat-treated at 500 degrees C in flowing N2 for 2 h. The resulting mixed metal oxides were characterized by several physico-chemical techniques and tested in both the liquid phase catalytic oxidation of diphenyl sulfide (DPS), in friendly environmental conditions (using tert-butyl hydroperoxide as oxidant), and in the gas phase partial oxidation of hydrogen sulfide to sulfur (using air at oxidant). Although the catalytic behavior of these catalysts strongly depends on the composition of catalysts, high activity and selectivity have been achieved over mixed metal oxides in both reactions. The good catalytic performance of species containing Cu(II) was evidenced in both reactions studied and the reactivity of this element could be explained by its structural and vibrational spectroscopic properties.

Interactions between effects generated by non-thermal plasma (NTP) and catalysts are increasingly investigated, ranging from energy conversion and material synthesis to pollutant degradation (e.g. volatile organic compounds, VOCs) and water purification. To make the water ecosystem more environmentally and economically sustainable, green and efficient wastewater treatment technologies are urgently required. In this study, a plasmacatalytic bubble column reactor was designed to generate underwater plasma bubbles (PBs) for efficient delivery of plasma-produced gaseous reactive oxidative species to the liquid phase for subsequent applications. This system shows great potential for degrading a stubborn water contaminant azophloxine (AP), which was further enhanced with an addition of CeO2 catalysts, resulting in the catalytic oxidation of the azo dyes. Moreover, the performances and durability of CeO2 were further improved via plasma pre-activation. The plasma-treated CeO2 (CeO2-P) displayed a combination of favourable properties, such as a higher concentration of oxygen vacancies and Ce3+ (observed by XPS), a narrowed energy bandgap, and an increased specific surface area (by 41.39%). Compared with the sole PBs and PBs/CeO2 systems, the highest removal efficiency and kinetic constant up to 99.5% and 0.907 min−1, respectively, were achieved in the PBs/CeO2-P system. Reactive species trapping corroborated that ·OH and ·O2– played an integral part in AP degradation. Finally, intermediates in the process of AP degradation were identified and a degradation pathway was proposed. This research would offer a promising remediation methodology for water purification via the integration of underwater plasma bubbles and CeO2 catalysts.

Recently, germanium selenide (GeSe) has emerged as a promising van der Waals semiconductor for photovoltaics, solar light harvesting, and water photoelectrolysis cells. Contrary to previous reports claiming perfect ambient stability based on experiments with techniques without surface sensitivity, here, by means of surface-science investigations and density functional theory, it is demonstrated that actually both: i) the surface of bulk crystals; and ii) atomically thin flakes of GeSe are prone to oxidation, with the formation of self-assembled germanium-oxide skin with sub-nanometric thickness. Surface oxidation leads to the decrease of the bandgap of stoichiometric GeSe and GeSe1−x, while bandgap energy increases upon surface oxidation of Ge1−xSe. Remarkably, the formation of a surface oxide skin on GeSe crystals plays a key role in the physicochemical mechanisms ruling photoelectrocatalysis: the underlying van der Waals semiconductor provides electron–hole pairs, while the germanium-oxide skin formed upon oxidation affords the active sites for catalytic reactions. The self-assembled germanium-oxide/germanium-selenide heterostructure with different bandgaps enables the activation of photocatalytic processes by absorption of light of different wavelengths, with inherently superior activity. Finally, it is discovered that, depending on the specific solvent-GeSe interaction, the liquid phase exfoliation of bulk crystals can induce the formation of Se nanowires. © 2021 The Authors. Advanced Functional Materials published by Wiley-VCH GmbH

Electrocatalytic water oxidation requires efficient catalysts to reduce the overpotential and accelerate the sluggish kinetics of oxygen formation. Here, a promising NiFeBa material was prepared by the co-electrodeposition of Ba2+, Ni2+, and Fe3+ as an efficient catalyst for electrocatalytic water oxidation. NiFeBa showed enhanced water oxidation performance compared with NiFe layered double hydroxide and NiFe oxide, delivering a current density of 10 mA cm−2 at an overpotential of 180 mV. Doped Ba ions played a key role in stabilizing the electrogenerated Ni3+ species, producing more octahedral Ni−O structures for lattice oxygen-based water oxidation, adjusting the catalytic mechanism, and finally leading to an enhancement of catalytic efficiency., QC 20220314

Titanium complexes of silanol functionalized polyoxometalates (THA)(3)[SbW9O33(RSiO)(3)Ti((OPr)-Pr-i)] (Ti-SiloxPOMs) catalyze alkene oxidation with tert-butyl hydrogen peroxide (TBHP). However catalytic activity and product distribution in the oxidation of allylic alcohols are shown to depend on the steric surrounding generated by the SiloxPOM (R=Bu-t, Pr-i, Pr-n). Combined experimental and computational studies clarify how steric repulsions between the oxidant (Bu-t group) and the surrounding SiloxPOM govern the reaction pathways leading either to oxidation of the alcohol function (R=Bu-t) or to alkene epoxidation (R=Pr-n). Moreover, another consequence of this steric repulsive interactions is that outer-sphere mechanisms become competitive with the inner-sphere ones (coordination of allylic alcohol), whether for the oxidative dehydrogenation reaction or for the epoxidation reaction. In the case of unfunctionalized olefins (linear and cyclic), we show that reducing the bulkiness surrounding the active site leads to higher conversion to epoxide, emphasizing that these Ti-SiloxPOMs may behave as structural and functional models for metal single-site in Ti-Silicates.

A novel one-step method to prepare the nanocomposites of reduced graphene oxide (RGO)/nanoporous gold (NPG) is realized by chemically dealloying an Al2Au precursor. The RGO nanosheets anchored on the surface of NPG have a cicada wing like shape and act as both conductive agent and buffer layer to improve the catalytic ability of NPG for methanol electro-oxidation reaction (MOR). This improvement can also be ascribed to the microstructure change of NPG in dealloying with RGO. This work inspires a facile and economic method to prepare the NPG based catalyst for MOR.

Low-temperature oxidative degradation of formaldehyde (HCHO) using non-noble metal catalysts is challenging. Herein, novel manganese dioxide (MnO2)/N-doped carbon nanotubes (NCNT) composites were prepared with varying MnO2 content. The surface properties and morphologies were analyzed using X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and transmission electron microscope (TEM). Comparing with MnO2/carbon nanotubes (CNTs) catalyst, the 40% MnO2/NCNT exhibited much better activity and selectivity for HCHO oxidation, mineralizing 95% of HCHO (at 100 ppm) into CO2 at 30 °C at a gas hourly space velocity (GHSV) of 30,000 mL h-1 g-1. Density functional theory (DFT) calculation was used to analyze the difference in the catalytic activity of MnO2 with CNTs and NCNT carrier. It was confirmed that the oxygen on NCNT was more active than CNTs, which facilitated the regeneration of MnO2. This resulted in remarkably boosted activity for HCHO oxidation. The present work thus exploited an inexpensive approach to enhance the catalytic activity of transition metal oxides via depositing them on a suitable support.

The role of bio- and chemo-catalytic aerobic oxidations in the production of commodity chemicals in a bio-refinery is reviewed. The situation is fundamentally different to that in a petrochemicals refinery where the feedstocks are gaseous or liquid hydrocarbons that are oxidized at elevated temperatures in the vapor or liquid phase under solvent-free conditions. In contrast, the feedstocks in a biorefinery are carbohydrates that are water soluble solids and their conversion will largely involve aerobic oxidations of hydroxyl functional groups in water as the solvent under relatively mild conditions of temperature and pressure. This will require the development and use of cost-effective and environmentally attractive processes using both chemo- and biocatalytic methods for alcohols and polyols., BT/Biocatalysis

The growth of ultrathin layers of VOx (< 12 monolayers) on Pt(111) and the activity of these layers in catalytic methanol oxidation at 10−4 mbar have been studied with low-energy electron diffraction, Auger electron spectroscopy, rate measurements, and with photoemission electron microscopy. Reactive deposition of V in O2 at 670 K obeys a Stranski–Krastanov growth mode with a (√3 × √3)R30° structure representing the limiting case for epitaxial growth of 3D-VOx. The activity of VOx/Pt(111) in catalytic methanol oxidation is very low and no redistribution dynamics is observed lifting the initial spatial homogeneity of the VOx layer. Under reaction conditions, part of the surface vanadium diffuses into the Pt subsurface region. Exposure to O2 causes part of the V to diffuse back to the surface, but only up to one monolayer of VOx can be stabilized in this way at 10−4 mbar.

While Co3O4 represents one of the most promising catalysts for soot oxidation, conventional Co3O4 nanoparticles (NPs) tend to aggregate, losing their activities. Herein, an alternative approach is proposed for preparing three-dimensional nanostructured Co3O4 (NSCo) using the hierarchically-structured Co-based Metal Organic Frameworks as a precursor. Specifically, ZIF-67 is chosen as the precursor as ZIF-67 can be conveniently synthesized with high yields and it can be easily converted to NSCo via calcination. The resulting NSCo exhibits a unique morphology which enables NSCo to possess more porosities and surface areas than the typical Co3O4 NPs. Consequently, NSCo shows a much higher catalytic activity than the typical Co3O4 NPs for soot oxidation because of superior textural properties of NSCo. Besides, when the soot oxidation by the typical Co3O4 NPs produced a significant amount of unwanted CO, soot can be completely combusted into CO2 using NSCo. In comparison with other reported Co-related catalysts, NSCo also achieves a higher soot oxidation efficiency (100% conversion) at lower temperatures with Tig of 331 °C. NSCo can be reused over many continuous cycles and still retains its catalytic activities. These features validate that NSCo is an easy-to-prepare 3D nanostructured Co3O4 catalyst, which possesses advantageous capabilities for soot oxidation at lower temperatures.

A novel one-step method to prepare the nanocomposites of reduced graphene oxide (RGO)/nanoporous gold (NPG) is realized by chemically dealloying an Al2Au precursor. The RGO nanosheets anchored on the surface of NPG have a cicada wing like shape and act as both conductive agent and buffer layer to improve the catalytic ability of NPG for methanol electro-oxidation reaction (MOR). This improvement can also be ascribed to the microstructure change of NPG in dealloying with RGO. This work inspires a facile and economic method to prepare the NPG based catalyst for MOR.

The role of bio- and chemo-catalytic aerobic oxidations in the production of commodity chemicals in a bio-refinery is reviewed. The situation is fundamentally different to that in a petrochemicals refinery where the feedstocks are gaseous or liquid hydrocarbons that are oxidized at elevated temperatures in the vapor or liquid phase under solvent-free conditions. In contrast, the feedstocks in a biorefinery are carbohydrates that are water soluble solids and their conversion will largely involve aerobic oxidations of hydroxyl functional groups in water as the solvent under relatively mild conditions of temperature and pressure. This will require the development and use of cost-effective and environmentally attractive processes using both chemo- and biocatalytic methods for alcohols and polyols., BT/Biocatalysis

El presente trabajo tiene como objetivo principal, evaluar la degradación de azul de metileno (AM) remanente en la muestra de agua residual de un tratamiento previo de oxidación catalítica de aguas residuales, provenientes del laboratorio de microbiología de la Pontificia Universidad Javeriana (PUJ) mediante la técnica de oxidación de aire húmedo con peróxido de hidrógeno (CWPO) empleando óxidos mixtos de Mn, Cu y/o Fe como catalizadores. Estos fueron sintetizados empleando el método de autocombustión, y se llevó a cabo la reacción a condiciones ambiente con las siguientes variables de operación: temperatura 30ºC, presión ambiente, flujo de aire de 2mL/min, 0,5g de Fe 2,5mMol/g de sólido, y 10mL de H2O2 30%w/w.

El presente trabajo tiene como objetivo principal, evaluar la degradación de azul de metileno (AM) remanente en la muestra de agua residual de un tratamiento previo de oxidación catalítica de aguas residuales, provenientes del laboratorio de microbiología de la Pontificia Universidad Javeriana (PUJ) mediante la técnica de oxidación de aire húmedo con peróxido de hidrógeno (CWPO) empleando óxidos mixtos de Mn, Cu y/o Fe como catalizadores. Estos fueron sintetizados empleando el método de autocombustión, y se llevó a cabo la reacción a condiciones ambiente con las siguientes variables de operación: temperatura 30ºC, presión ambiente, flujo de aire de 2mL/min, 0,5g de Fe 2,5mMol/g de sólido, y 10mL de H2O2 30%w/w.

Lignin depolymerisation receives great attention due to the pressing need to find sustainable alternatives to fossil sources for production of fuels and chemicals. In this study, alumina-supported Cu-Mn and Ni-Mo catalysts were tested for oxidative depolymerisation of a technical lignin stream – sodium lignosulphonates – to produce valuable low-molecular-weight aromatics that may be considered for applications in the fuels and chemicals sector. The reactions were performed at elevated temperature and oxygen pressure, and the product mixtures were analysed by size exclusion chromatography (SEC), two-dimensional nuclear magnetic resonance (NMR) spectroscopy and supercritical fluid chromatography mass spectrometry (SFC-MS). The best performance was obtained with Cu-Mn/δ-Al2O3, which wasthoroughly characterised before and after use by nitrogen physisorption, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), powder X-ray diffraction (XRD), thermal gravimetric analysis (TGA), inductively coupled plasma optical emission spectrometry (ICP-OES) and X-ray photoelectron spectroscopy (XPS). Major products identified were p-vanillin, p-hydroxybenzaldehyde, vanillic acid and p-hydroxybenzoic acid as well as smaller aliphatic aldehydes, acids and lactones.

BACKGROUND Acetone is a volatile organic compound (VOC) that is often associated with poor air quality. Acetone has chronic toxicity towards humans and has significant impact to the overall atmospheric air quality. In this study, several layer double oxides (with M2+ = Mg, Ni, Co or Mn and M3+= Al or Ce)were tested as catalyst in acetone oxidation. RESULTS MnAl-LDO was found to be the most efficient catalyst. 50% acetone conversion was achieved at 170 °C (T50%) and 90% conversion at 200 °C (T90%).The incorporation of Ce on MnCeAl-LDO did not improve its catalytic properties over MnAl-LDO (the T50% for MnCeAl-LDO was 12 °C higher than for MnAl-LDO). The good performance on MnAl-LDO was due to the presence of Mn3+. MnAl-LDO was not affect when water was introduced into the catalytic reaction setup. Less than 5 % fluctuation in the acetone conversion rate at 170 and 200 °C was detected in the presence of 5.5% water. The incorporation of Ce on CoCeAl-LDO improved its catalytic performance over CoAl-LDO (T50% of CoCeAl-LDO was 15 °C lower than CoAl-LDO).Our results showed that the good catalytic performance of CoCeAl-LDO was ascribed to the increased Co2+/Co3+ ratio and the abundance of lattice oxygen (Olatt). CONCLUSION MnAl-LDO has good catalytic properties for acetone oxidation, even under humid conditions. The LDO catalysts tested here can be developed into efficient catalysts for acetone oxidation and serve as functional materials for the reduction in acetone or VOC emission. This article is protected by copyright. All rights reserved.

BACKGROUND Acetone is a volatile organic compound (VOC) that is often associated with poor air quality. Acetone has chronic toxicity towards humans and has significant impact to the overall atmospheric air quality. In this study, several layer double oxides (with M2+ = Mg, Ni, Co or Mn and M3+= Al or Ce)were tested as catalyst in acetone oxidation. RESULTS MnAl-LDO was found to be the most efficient catalyst. 50% acetone conversion was achieved at 170 °C (T50%) and 90% conversion at 200 °C (T90%).The incorporation of Ce on MnCeAl-LDO did not improve its catalytic properties over MnAl-LDO (the T50% for MnCeAl-LDO was 12 °C higher than for MnAl-LDO). The good performance on MnAl-LDO was due to the presence of Mn3+. MnAl-LDO was not affect when water was introduced into the catalytic reaction setup. Less than 5 % fluctuation in the acetone conversion rate at 170 and 200 °C was detected in the presence of 5.5% water. The incorporation of Ce on CoCeAl-LDO improved its catalytic performance over CoAl-LDO (T50% of CoCeAl-LDO was 15 °C lower than CoAl-LDO).Our results showed that the good catalytic performance of CoCeAl-LDO was ascribed to the increased Co2+/Co3+ ratio and the abundance of lattice oxygen (Olatt). CONCLUSION MnAl-LDO has good catalytic properties for acetone oxidation, even under humid conditions. The LDO catalysts tested here can be developed into efficient catalysts for acetone oxidation and serve as functional materials for the reduction in acetone or VOC emission. This article is protected by copyright. All rights reserved.

BACKGROUND Acetone is a volatile organic compound (VOC) that is often associated with poor air quality. Acetone has chronic toxicity towards humans and has significant impact to the overall atmospheric air quality. In this study, several layer double oxides (with M2+ = Mg, Ni, Co or Mn and M3+= Al or Ce)were tested as catalyst in acetone oxidation. RESULTS MnAl-LDO was found to be the most efficient catalyst. 50% acetone conversion was achieved at 170 °C (T50%) and 90% conversion at 200 °C (T90%).The incorporation of Ce on MnCeAl-LDO did not improve its catalytic properties over MnAl-LDO (the T50% for MnCeAl-LDO was 12 °C higher than for MnAl-LDO). The good performance on MnAl-LDO was due to the presence of Mn3+. MnAl-LDO was not affect when water was introduced into the catalytic reaction setup. Less than 5 % fluctuation in the acetone conversion rate at 170 and 200 °C was detected in the presence of 5.5% water. The incorporation of Ce on CoCeAl-LDO improved its catalytic performance over CoAl-LDO (T50% of CoCeAl-LDO was 15 °C lower than CoAl-LDO).Our results showed that the good catalytic performance of CoCeAl-LDO was ascribed to the increased Co2+/Co3+ ratio and the abundance of lattice oxygen (Olatt). CONCLUSION MnAl-LDO has good catalytic properties for acetone oxidation, even under humid conditions. The LDO catalysts tested here can be developed into efficient catalysts for acetone oxidation and serve as functional materials for the reduction in acetone or VOC emission. This article is protected by copyright. All rights reserved.

[EN] Mayenite (Ca12Al14O33) was synthesized by a novel route based on the use of polymethyl methacrylate (PMMA) as a soft templating agent. The material was tested for the total oxidation of trichloroethylene in the gas phase and the catalytic performance was analysed when using different initial amounts of PMMA in the catalyst synthesis. The results were compared with those obtained with a mayenite synthetized by a classical hydrothermal method. The highest activity in terms of TCE conversion was achieved in the presence of mayenite prepared using 10% w/w of PMMA; its activity was also higher than that of the hydrothermal mayenite. The surface area and the number of superoxide anions (O-2(-)) seem to be the main properties determining the catalytic activity of the material.

[EN] Mayenite was recently successfully employed as an active catalyst for trichloroethylene (TCE) oxidation. It was effective in promoting the conversion of TCE in less harmful products (CO2 and HCl) with high activity and selectivity. However, there is a potential limitation to the use of mayenite in the industrial degradation of chlorinated compounds-its limited operating lifespan owing to chlorine poisoning of the catalyst. To overcome this problem, in this work, mayenite-based catalysts loaded with iron (Fe/mayenite) were prepared and tested for TCE oxidation in a gaseous phase. The catalysts were characterized using different physico-chemical techniques, including XRD, ICP, N-2-sorption (BET), H-2-TPR analysis, SEM-EDX, XPS FESEM-EDS, and Raman. Fe/mayenite was found to be more active and stable than the pure material for TCE oxidation, maintaining the same selectivity. This result was interpreted as the synergistic effect of the metal and the oxo-anionic species present in the mayenite framework, thus promoting TCE oxidation, while avoiding catalyst deactivation.

[EN] Mayenite was recently successfully employed as an active catalyst for trichloroethylene (TCE) oxidation. It was effective in promoting the conversion of TCE in less harmful products (CO2 and HCl) with high activity and selectivity. However, there is a potential limitation to the use of mayenite in the industrial degradation of chlorinated compounds-its limited operating lifespan owing to chlorine poisoning of the catalyst. To overcome this problem, in this work, mayenite-based catalysts loaded with iron (Fe/mayenite) were prepared and tested for TCE oxidation in a gaseous phase. The catalysts were characterized using different physico-chemical techniques, including XRD, ICP, N-2-sorption (BET), H-2-TPR analysis, SEM-EDX, XPS FESEM-EDS, and Raman. Fe/mayenite was found to be more active and stable than the pure material for TCE oxidation, maintaining the same selectivity. This result was interpreted as the synergistic effect of the metal and the oxo-anionic species present in the mayenite framework, thus promoting TCE oxidation, while avoiding catalyst deactivation.

The emission of volatile organic compounds (VOCs) from industrial and commercial processes is detrimental to human health and the environment. Though numerous catalysts have been reported to eliminate the pollution of VOCs, their deactivation and regeneration are still largely unknown. In this study, the prepared palygorskite-supported Cu-Mn oxides displays slight decrease of catalytic activity in the initial stage of formaldehyde oxidation. After the thermal treatment of spent catalyst at 400 °C, the catalytic activity is partially recovered. A deactivation and regeneration mechanism is proposed, based on the stability test and the comprehensive characterizations of fresh and spent catalysts. The accumulation of formate species and the depletion of oxygen on the surface of Cu-Mn oxides are responsible for the decline of activity. Thermal treatment of deactivated catalyst at 400 °C recovers the catalytic activity because it gasifies the carbonaceous intermediates and replenishes surface oxygen. The obtained results will be of great significance for the application of transition metal oxide-based catalysts in the abatement of VOCs.

El presente trabajo tiene como objetivo principal, evaluar la degradación de azul de metileno (AM) remanente en la muestra de agua residual de un tratamiento previo de oxidación catalítica de aguas residuales, provenientes del laboratorio de microbiología de la Pontificia Universidad Javeriana (PUJ) mediante la técnica de oxidación de aire húmedo con peróxido de hidrógeno (CWPO) empleando óxidos mixtos de Mn, Cu y/o Fe como catalizadores. Estos fueron sintetizados empleando el método de autocombustión, y se llevó a cabo la reacción a condiciones ambiente con las siguientes variables de operación: temperatura 30ºC, presión ambiente, flujo de aire de 2mL/min, 0,5g de Fe 2,5mMol/g de sólido, y 10mL de H2O2 30%w/w.

Hydrotalcite like compounds containing Co, Al and Ce were synthesized by co-precipitation. The mixed oxides obtained after calcination were characterized by several techniques: XRD, BET, H2-TPR and XPS. Activities of mixed oxides were evaluated in toluene total oxidation in presence or in absence of carbon monoxide. The benzene, benzyl alcohol and benzaldehyde are principal by-products observed during toluene oxidation in presence of CoAl(Ce) mixed oxides. Moreover, presence of carbon monoxide improves toluene total oxidation over CoAlCe mixed oxides. Stability of the two best catalytic materials has been tested in the two conditions and show no deactivation.

BACKGROUND Acetone is a volatile organic compound (VOC) that is often associated with poor air quality. Acetone has chronic toxicity towards humans and has significant impact to the overall atmospheric air quality. In this study, several layer double oxides (with M2+ = Mg, Ni, Co or Mn and M3+= Al or Ce)were tested as catalyst in acetone oxidation. RESULTS MnAl-LDO was found to be the most efficient catalyst. 50% acetone conversion was achieved at 170 °C (T50%) and 90% conversion at 200 °C (T90%).The incorporation of Ce on MnCeAl-LDO did not improve its catalytic properties over MnAl-LDO (the T50% for MnCeAl-LDO was 12 °C higher than for MnAl-LDO). The good performance on MnAl-LDO was due to the presence of Mn3+. MnAl-LDO was not affect when water was introduced into the catalytic reaction setup. Less than 5 % fluctuation in the acetone conversion rate at 170 and 200 °C was detected in the presence of 5.5% water. The incorporation of Ce on CoCeAl-LDO improved its catalytic performance over CoAl-LDO (T50% of CoCeAl-LDO was 15 °C lower than CoAl-LDO).Our results showed that the good catalytic performance of CoCeAl-LDO was ascribed to the increased Co2+/Co3+ ratio and the abundance of lattice oxygen (Olatt). CONCLUSION MnAl-LDO has good catalytic properties for acetone oxidation, even under humid conditions. The LDO catalysts tested here can be developed into efficient catalysts for acetone oxidation and serve as functional materials for the reduction in acetone or VOC emission. This article is protected by copyright. All rights reserved.

El presente trabajo tiene como objetivo principal, evaluar la degradación de azul de metileno (AM) remanente en la muestra de agua residual de un tratamiento previo de oxidación catalítica de aguas residuales, provenientes del laboratorio de microbiología de la Pontificia Universidad Javeriana (PUJ) mediante la técnica de oxidación de aire húmedo con peróxido de hidrógeno (CWPO) empleando óxidos mixtos de Mn, Cu y/o Fe como catalizadores. Estos fueron sintetizados empleando el método de autocombustión, y se llevó a cabo la reacción a condiciones ambiente con las siguientes variables de operación: temperatura 30ºC, presión ambiente, flujo de aire de 2mL/min, 0,5g de Fe 2,5mMol/g de sólido, y 10mL de H2O2 30%w/w.

El presente trabajo tiene como objetivo principal, evaluar la degradación de azul de metileno (AM) remanente en la muestra de agua residual de un tratamiento previo de oxidación catalítica de aguas residuales, provenientes del laboratorio de microbiología de la Pontificia Universidad Javeriana (PUJ) mediante la técnica de oxidación de aire húmedo con peróxido de hidrógeno (CWPO) empleando óxidos mixtos de Mn, Cu y/o Fe como catalizadores. Estos fueron sintetizados empleando el método de autocombustión, y se llevó a cabo la reacción a condiciones ambiente con las siguientes variables de operación: temperatura 30ºC, presión ambiente, flujo de aire de 2mL/min, 0,5g de Fe 2,5mMol/g de sólido, y 10mL de H2O2 30%w/w.

BACKGROUND Acetone is a volatile organic compound (VOC) that is often associated with poor air quality. Acetone has chronic toxicity towards humans and has significant impact to the overall atmospheric air quality. In this study, several layer double oxides (with M2+ = Mg, Ni, Co or Mn and M3+= Al or Ce)were tested as catalyst in acetone oxidation. RESULTS MnAl-LDO was found to be the most efficient catalyst. 50% acetone conversion was achieved at 170 °C (T50%) and 90% conversion at 200 °C (T90%).The incorporation of Ce on MnCeAl-LDO did not improve its catalytic properties over MnAl-LDO (the T50% for MnCeAl-LDO was 12 °C higher than for MnAl-LDO). The good performance on MnAl-LDO was due to the presence of Mn3+. MnAl-LDO was not affect when water was introduced into the catalytic reaction setup. Less than 5 % fluctuation in the acetone conversion rate at 170 and 200 °C was detected in the presence of 5.5% water. The incorporation of Ce on CoCeAl-LDO improved its catalytic performance over CoAl-LDO (T50% of CoCeAl-LDO was 15 °C lower than CoAl-LDO).Our results showed that the good catalytic performance of CoCeAl-LDO was ascribed to the increased Co2+/Co3+ ratio and the abundance of lattice oxygen (Olatt). CONCLUSION MnAl-LDO has good catalytic properties for acetone oxidation, even under humid conditions. The LDO catalysts tested here can be developed into efficient catalysts for acetone oxidation and serve as functional materials for the reduction in acetone or VOC emission. This article is protected by copyright. All rights reserved.

El presente trabajo tiene como objetivo principal, evaluar la degradación de azul de metileno (AM) remanente en la muestra de agua residual de un tratamiento previo de oxidación catalítica de aguas residuales, provenientes del laboratorio de microbiología de la Pontificia Universidad Javeriana (PUJ) mediante la técnica de oxidación de aire húmedo con peróxido de hidrógeno (CWPO) empleando óxidos mixtos de Mn, Cu y/o Fe como catalizadores. Estos fueron sintetizados empleando el método de autocombustión, y se llevó a cabo la reacción a condiciones ambiente con las siguientes variables de operación: temperatura 30ºC, presión ambiente, flujo de aire de 2mL/min, 0,5g de Fe 2,5mMol/g de sólido, y 10mL de H2O2 30%w/w.

La industrialización ha generado el desarrollo de nuevas tecnologías de producción en conjunto con políticas de control respecto a los vertimientos de residuos y subproductos emanados en cada una de las etapas teniendo en cuenta la protección del medio ambiente; es así como se busca la remoción de sustancias altamente tóxicas como lo son los colorantes sintéticos generados en los efluentes de diferentes industrias a partir de técnicas novedosas, eficientes y rentables a escala industrial. Los catalizadores de óxidos mixtos Mn y/o Cu en diferentes relaciones molares fueron preparados a partir del método de auto combustión y caracterizados por las técnicas DRX, TPR-H2, isotermas de adsorción-desorción de N2 y absorbancia atómica. Los sólidos son evaluados en la degradación del cristal violeta (CV) mediante la oxidación catalítica en fase húmeda con H2O2 en condiciones moderadas de reacción: temperatura a 25°C, presión ambiente, flujo de aire de 2 mL/min y 0,1M 2ml/h de H2O2, mostrando una alta actividad y selectividad. Los resultados experimentales evidenciaron degradaciones del 100% del CV, conversión del carbono orgánico total (TOC) del 74%, eliminación del DQO del 71%, en tiempos aproximados de 90 minutos de reacción. Adicionalmente, se hace un seguimiento de la selectividad por CG-MS encontrando que hay una mineralización casi completa en poco tiempo de reacción, generando productos intermediarios de ácidos carboxílicos, alcoholes y aminas que no causan riesgo severo al medio ambiente. El catalizador MnCu con relaciones molares de 1:2 resulto ser el catalizador más promisor evidenciando un efecto cooperativo entre los dos metales y la importancia de las propiedades redox para la eliminación del colorante CV en aguas residuales.

La industrialización ha generado el desarrollo de nuevas tecnologías de producción en conjunto con políticas de control respecto a los vertimientos de residuos y subproductos emanados en cada una de las etapas teniendo en cuenta la protección del medio ambiente; es así como se busca la remoción de sustancias altamente tóxicas como lo son los colorantes sintéticos generados en los efluentes de diferentes industrias a partir de técnicas novedosas, eficientes y rentables a escala industrial. Los catalizadores de óxidos mixtos Mn y/o Cu en diferentes relaciones molares fueron preparados a partir del método de auto combustión y caracterizados por las técnicas DRX, TPR-H2, isotermas de adsorción-desorción de N2 y absorbancia atómica. Los sólidos son evaluados en la degradación del cristal violeta (CV) mediante la oxidación catalítica en fase húmeda con H2O2 en condiciones moderadas de reacción: temperatura a 25°C, presión ambiente, flujo de aire de 2 mL/min y 0,1M 2ml/h de H2O2, mostrando una alta actividad y selectividad. Los resultados experimentales evidenciaron degradaciones del 100% del CV, conversión del carbono orgánico total (TOC) del 74%, eliminación del DQO del 71%, en tiempos aproximados de 90 minutos de reacción. Adicionalmente, se hace un seguimiento de la selectividad por CG-MS encontrando que hay una mineralización casi completa en poco tiempo de reacción, generando productos intermediarios de ácidos carboxílicos, alcoholes y aminas que no causan riesgo severo al medio ambiente. El catalizador MnCu con relaciones molares de 1:2 resulto ser el catalizador más promisor evidenciando un efecto cooperativo entre los dos metales y la importancia de las propiedades redox para la eliminación del colorante CV en aguas residuales.

The harmful emissions of chlorinated volatile organic compounds (CVOCs) originate only from man-made sources. CVOCs are used in a variety of applications from pharmaceuticals production to decaffeination of coffee. Currently, CVOC emissions are limited by strict legislation. For these reasons, efficient CVOC abatement technologies are required. Catalytic oxidation is very promising option for this purpose, since catalysts can be tailored to each case to maximize the efficiency and minimize the formation of unwanted products, such as dioxins or Cl2. The goal of this thesis was to study the role of the physico-chemical properties of catalysts in dichloromethane (DCM) oxidation. To reach the aim, several catalytic materials were prepared and characterized, and their performance was tested in total oxidation of DCM. The catalytic materials used were powders of four single metal oxides (γ-Al2O3, TiO2, CeO2, MgO), three mixed oxides (Al2O3-xSiO2) washcoated on a cordierite monolith and four active phases (Pt, Cu, V, Mn). At first, support properties were studied. It was found that the DCM conversion and HCl production are dependent on support acidity when the studied single oxides are considered. The best DCM conversions and HCl yields were observed with the support having the highest total acidity (γ-Al2O3). Further, the quality of the by-products formed was dependent on the type of the acid sites present on the support surface. Secondly, the impregnation of the active compound was observed to improve the selectivity of the material. From the tested active phases, Pt presented the best performance, but also V2O5 and CuO showed almost equal performances. Especially CuO supported on γ-Al2O3, that had less formation of by-products and is less toxic than V-containing oxides, seems to be a promising alternative to Pt. Concerning stability, no deactivation was observed after 55h of testing of Pt/Al2O3. Furthermore, in the used reaction conditions, the f, Tiivistelmä Haitallisten kloorattujen orgaanisten yhdisteiden (CVOC) päästöt ovat ihmisten aiheuttamia. CVOC-yhdisteitä käytetään mm. liuottimina lääkeaineiden valmistuksessa ja kofeiinin poistossa. Nykyisin CVOC-päästöjä rajoitetaan tiukalla lainsäädännöllä. Näistä syistä tehokas CVOC-yhdisteiden käsittelymenetelmä on tarpeen. Katalyyttinen hapetus on hyvä vaihtoehto tähän tarkoitukseen, koska katalyytit voidaan räätälöidä niin, että puhdistuksen tehokkuus saadaan maksimoitua samalla kun ei-haluttujen tuotteiden, kuten dioksiinit ja kloorikaasu, muodostuminen voidaan minimoida. Tämän väitöskirjatyön tavoitteena oli selvittää katalyyttien fysikaalis-kemiallisten ominaisuuksien yhteyksiä dikloorimetaanin (DCM) hapetukseen. Tavoitteen saavuttamiseksi valmistettiin useita katalyyttejä, jotka karakterisoitiin ja testattiin DCM:n kokonaishapetuksessa. Työssä tutkittiin neljää jauhemaista metallioksidia (γ-Al2O3, TiO2, CeO2 ja MgO), kolmea metallioksidiseosta (Al2O3-xSiO2), jotka pinnoitettiin kordieriittimonoliitille, sekä neljää aktiivista ainetta: Pt, Cu, V and Mn. Aluksi työssä keskityttiin tukiaineiden ominaisuuksiin. Työn tulokset osoittivat, että DCM:n konversio ja HCl:n tuotanto ovat riippuvaisia tukiaineen happamuudesta. Paras tulos saavutettiin alumiinioksidilla, jolla oli korkein kokonaishappamuus. Lisäksi havaittiin, että sivutuotteiden laatu riippuu tukiaineen pinnalla olevien happopaikkojen tyypistä. Aktiivisen aineen impregnointi tukiaineeseen paransi materiaalin selektiivisyyttä. Tutkituista aineista Pt osoittautui parhaimmaksi, mutta myös V2O5 ja CuO olivat lähes yhtä hyviä. Erityisesti CuO-katalyytti, joka tuotti vähemmän sivutuotteita ja joka on materiaalina vähemmän haitallinen kuin V2O5, osoittautui lupaavaksi jalometallikatalyyttien korvaajaksi. Materiaalien stabiilisuuteen liittyen Pt/Al2O3-katalyytin toiminnassa ei havaittu muutoksia 55 tunnin testauksen jälkeen. Lisäksi CuCl2:n muodostuminen ei mallinnuksen mukaan ole termodynaamisesti todenn

This work describes the development of a modified glassy carbon electrode (GCE) for the selective determination of 2,4-diaminotoluene (TDA), a primary aromatic amines (PAAs) that can be formed in food packaging materials including aromatic polyurethane (PU) adhesives. The electrode's surface was modified with multi-walled carbon nanotubes (MWCNTs), MWCNTs in chitosan (CS), and gold nanoparticles (AuNPs). The highest current response was achieved with AuNPs/MWCNTs-CS/GC electrodes, which exhibited an oxidation peak of 9.87 μA by cyclic voltammetry (CV), compared with 1.39 μA of the bare GCE. A detection limit of 35 nM was estimated by amperometry experiments. The oxidation of TDA was strongly dependent on the pH of the medium, having maximum sensitivity at pH ∼ 7. From a mechanistic point of view, the diffusion coefficient of TDA (D = 6.47 × 10−4 cm2 s−1) and the number of electrons (n ≈ 2) involved in the catalytic oxidation of TDA at the surface of the AuNPs/MWCNTs-CS/GCE were determined. The practical utility of this nanocomposite modified electrode was demonstrated by migration studies from conventional food packaging materials., QC 20181127

Commercial catalysts for the catalytic oxidation of chloroaromatics are mainly based on either noble metals or transition metal oxides supported on a suitable carrier. This paper reviews studies relative to these two generic groups of catalysts and their performances for chloroaromatic decomposition, i.e. conversion efficiency, stability and selectivity towards harmless products (e.g., CO2), and in particular, avoiding the formation of polychlorinated by-products. The various approaches towards improved catalysts, including tuning the support, adding dopants or promoters, improving the preparation methods, or auxiliary means such as the introduction of ozone (O3) or hydrogen peroxide (H2O2) in the gas to be treated, and combination with non-thermal plasma treatment are systematically reviewed. This review also appraises various modes of deactivation (i.e., originating from fouling, coking, poisoning, sintering of the catalyst, and from volatilization of its active phases) as well as possible methods for regeneration.

The effect of the presence of residual sodium (0.4 %wt) over a Co3O4 bulk catalyst for methane combustion was studied. Two samples, with and without residual sodium, were synthesized by precipitation and thoroughly characterised by X-ray diffraction (XRD), N-2 physisorption, Wavelength Dispersive X-ray Fluorescence (WDXRF), temperature-programmed reduction with hydrogen followed by temperature-programmed reduction with oxygen (H-2-TPR/O-2-TPO), temperature-programmed reaction with methane (CH4 -TPRe), ultraviolet-visible-near-infrared diffuse reflectance spectroscopy (UV-vis-NIR DRS), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). It was found that during calcination, a fraction of the sodium atoms initially deposited on the surface diffused and migrated into the spinel lattice, inducing a distortion that improved its textural and structural properties. However, surface sodium had an overall negative impact on the catalytic activity. It led to a reduction of surface Co3+ ions in favour of Co2+, thus ultimately decreasing the Co3+/Co2+ molar ratio (from 1.96 to 1.20) and decreasing the amount and mobility of active lattice oxygen species. As a result, the catalyst with residual sodium (T-90 = 545 degrees C) was notably less active than its clean counterpart (T-90 = 500 degrees C). All of this outlined the significance of a proper washing when synthesizing Co3O4 catalyst using a sodium salt as the precipitating agent.