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Several supported liquid-phase (SLP) catalysts with immobilized Rh-biphephos complexes on monolithic supports were prepared and applied for continuous gas-phase hydroformylation (HyFo) of 1-butene. The support comprised macroporous monolithic silicon carbide (SiC) with deposited silica nanoparticles (NPs) in order to provide mesopores with enhanced capillary forces to retain the liquid-phase. Variable parameters were examined for the monolithic SiC supports, including size and loading of deposited silica NPs and intermediate calcination between silica deposition steps to obtain the most efficient support configuration for the SLP system. The SLP catalysts with larger deposited silica NPs gave higher catalytic activity (i.e. 1-butene conversion and turnover frequency) compared to the supports with smaller sized silica NPs. However, the selectivity towards the preferred linear aldehyde was higher in the SLP catalysts with supports containing less silica with small silica NPs. Importantly, the prepared SLP catalyst systems showed long-term stability in HyFo with negligible formation of high boiling aldol condensation products.

Microwave-assisted synthesis has attracted wide attention as an efficient and energy-saving synthesis strategy due to its unique heating mechanism. Environmental catalysts prepared via microwave heating process typically exhibit uniform crystal size with desired morphology, porous structure and interfacial properties, which are important for the catalytic remediation of air pollution. This review first summarizes the principles of microwave heating, followed by the characteristics of the obtained catalysts. The research progress of representative materials (e.g., supported metal catalysts, metal oxides, and porous carbon materials) in the treatment of gaseous pollutants are then categorized in detail. Meanwhile, this review compiles the recent research outputs of air pollutants remediation by environmental catalysts from the perspective of features and reaction pathways facilitated by microwave-assisted synthesis. It demonstrates that microwave-assisted heating can not only improve the synthesis efficiency and the catalytic activity but also modify the selectivity by tuning the catalyst properties. Finally, the use of microwave irradiation to activate environmental catalytic reactions is reviewed, as the application of microwaves can lead to significant improvements due to the possibility of delivering energy directly to the catalytic materials. Nevertheless, challenges remain in the development of highly active and efficient catalyst to realize its practical application. These, together with prospects on the development of environmental catalysts using microwave techniques are provided for enlightening the future of this field of research. © 2023 The Author(s)

El interés por los microplásticos (MPs) y sus efectos en la salud ha abierto un campo nuevo de estudio con un crecimiento exponencial. Los MPs se han detectado en numerosos alimentos y bebidas de consumo humano, así como en las heces humanas, mientras que desde la investigación se están proponiendo nuevos materiales y nuevas propiedades de bioplásticos para su uso industrial. El ácido poliláctico (PLA) es el bioplástico más utilizado en envases de alimentos y otros productos desechables, dispositivos biomédicos y procedimientos quirúrgicos. Sin embargo, a pesar de su demostrada biodegradabilidad y biocompatibilidad y de su estatus GRAS (Generally Recognised As Safe), estudios recientes en animales acuáticos e insectos han demostrado que las partículas de PLA pueden alterar las poblaciones microbianas intestinales. Comprender el potencial impacto de los MPs en la microbiota humana y su posible biotransformación en el tracto gastrointestinal es fundamental para evaluar sus riesgos potenciales a nivel digestivo y sistémico.En este trabajo se ha evaluado el efecto de la ingestión de una cantidad realista de MPs de PLA de dos tamaños distintos tras el paso por el tracto gastrointestinal humano. Para ello, se simuló el tránsito digestivo mediante la combinación del modelo in vitro estandarizado Infogest y la fermentación colónica en estático utilizando el simulador gastrointestinal simgi®. La fermentación se llevó a cabo en triplicado utilizando muestras fecales de donantes sanos (n=3). Los posibles cambios en la morfología de las partículas se monitorizaron mediante microscopía electrónica de barrido de emisión de campo (FESEM) y espectroscopía Raman. La composición y funcionalidad microbiana se analizó mediante secuenciación del gen ARNr 16S y predicción funcional bioinformática, y la actividad metabólica microbiana mediante el análisis de ácidos grasos de cadena corta y de ácido láctico. El análisis por FESEM mostró pequeñas perforaciones en la superficie de los MPs de

The accumulation of microplastics (MPs) in the environment as well as their presence in foods and humans highlight the urgent need for studies on the effects of these particles on humans. Polylactic acid (PLA) is the most widely used bioplastic in the food industry and medical field. Despite its biodegradability, biocompatibility, and “Generally Recognized As Safe” (GRAS) status, recent animal model studies have shown that PLA MPs can alter the intestinal microbiota; however, to date, no studies have been reported on the possible gut and health consequences of its intake by humans. This work simulates the ingestion of a realistic daily amount of PLA MPs and their pass through the gastrointestinal tract by combining the INFOGEST method and the gastrointestinal simgi® model to evaluate possible effects on the human colonic microbiota composition (16S rRNA gene sequencing analysis) and metabolic functionality (lactic acid and short-chain fatty acids (SCFA) production). Although PLA MPs did not clearly alter the microbial community homeostasis, increased Bifidobacterium levels tended to increase in presence of millimetric PLA particles. Furthermore, shifts detected at the functional level suggest an alteration of microbial metabolism, and a possible biotransformation of PLA by the human microbial colonic community. Raman spectroscopy and field emission scanning electron microscopy (FESEM) characterization revealed morphological changes on the PLA MPs after the gastric phase of the digestion, and the adhesion of organic matter as well as a microbial biofilm, with surface biodegradation, after the intestinal and colonic phases. With this evidence and the emerging use of bioplastics, understanding their impact on humans and potential biodegradation through gastrointestinal digestion and the human microbiota merits critical investigation.

Several supported liquid-phase (SLP) catalysts with immobilized Rh-biphephos complexes on monolithic supports were prepared and applied for continuous gas-phase hydroformylation (HyFo) of 1-butene. The support comprised macroporous monolithic silicon carbide (SiC) with deposited silica nanoparticles (NPs) in order to provide mesopores with enhanced capillary forces to retain the liquid-phase. Variable parameters were examined for the monolithic SiC supports, including size and loading of deposited silica NPs and intermediate calcination between silica deposition steps to obtain the most efficient support configuration for the SLP system. The SLP catalysts with larger deposited silica NPs gave higher catalytic activity (i.e. 1-butene conversion and turnover frequency) compared to the supports with smaller sized silica NPs. However, the selectivity towards the preferred linear aldehyde was higher in the SLP catalysts with supports containing less silica with small silica NPs. Importantly, the prepared SLP catalyst systems showed long-term stability in HyFo with negligible formation of high boiling aldol condensation products. © 2023, The Author(s).

Recently, the NMBP-35 Horizon 2020 projects - NanoMECommons, CHARISMA, and Easi-stress - organised a collaborative workshop to increase awareness of their contributions to the industry “commons” in terms of characterisation and digital transformation. They have established interoperability standards for knowledge management in characterisation and introduced new solutions for materials testing, aided by the standardisation of faster and more accurate assessment methods. The lessons learned from these projects and the discussions during the joint workshop emphasised the impact of recent developments and emerging needs in the field of characterisation. Specifically, the focus was on enhancing data quality through harmonisation and standardisation, as well as making advanced technologies and instruments accessible to a broader community with the goal of fostering increased trust in new products and a more skilled society. Experts also highlighted how characterisation and the corresponding experimental data can drive future innovation agendas towards technological breakthroughs. The focus of the discussion revolved around the characterisation and standardisation processes, along with the collection of modelling and characterisation tools, as well as protocols for data exchange. The broader context of materials characterisation and modelling within the materials community was explored, drawing insights from the Materials 2030 Roadmap and the experiences gained from NMBP-35 projects. This whitepaper has the objective of addressing common challenges encountered by the materials community, illuminating emerging trends and evolving techniques, and presenting the industry's perspective on emerging requirements and past success stories. It accomplishes this by providing specific examples and highlighting how these experiences can create fresh opportunities and strategies for newcomers entering the market. These advancements are anticipated to facilitate a more efficient transi

The accumulation of alkali metals generated during biomass combustion onto the catalysts employed for off-gas treatment can have a detrimental effect on their performance. This work investigates the effect of potassium as a model alkali on an efficient copper-based catalyst supported on SmCeO2 @TiO2. The addition of potassium modifies the redox properties of the Cu species or, more specifically, the metal-ceria interface, providing better catalytic activity for NO reduction in oxidizing conditions. SmCeO2 @TiO2 stabilizes highly dispersed copper species, and the presence of potassium introduces surface distortions that modify the lability of oxygen atoms. The results demonstrate the key role of surface defects and labile oxygen species associated with the CeO2 support. It was found that both Cu/SmCeO2 @TiO2 and K/Cu/SmCeO2 @TiO2 catalysts fully oxidized CO below 350 °C and actively reduced NO with CO in the presence of excess oxygen, reaching a maximum NO conversion of 65% at 316 °C and 83% at 330 °C, respectively, while undesired NO2 release was minimized in the alkaline-loaded sample. © 2023 Elsevier B.V.

Microwave-assisted synthesis has attracted wide attention as an efficient and energy-saving synthesis strategy due to its unique heating mechanism. Environmental catalysts prepared via microwave heating process typically exhibit uniform crystal size with desired morphology, porous structure and interfacial properties, which are important for the catalytic remediation of air pollution. This review first summarizes the principles of microwave heating, followed by the characteristics of the obtained catalysts. The research progress of representative materials (e.g., supported metal catalysts, metal oxides, and porous carbon materials) in the treatment of gaseous pollutants are then categorized in detail. Meanwhile, this review compiles the recent research outputs of air pollutants remediation by environmental catalysts from the perspective of features and reaction pathways facilitated by microwave-assisted synthesis. It demonstrates that microwave-assisted heating can not only improve the synthesis efficiency and the catalytic activity but also modify the selectivity by tuning the catalyst properties. Finally, the use of microwave irradiation to activate environmental catalytic reactions is reviewed, as the application of microwaves can lead to significant improvements due to the possibility of delivering energy directly to the catalytic materials. Nevertheless, challenges remain in the development of highly active and efficient catalyst to realize its practical application. These, together with prospects on the development of environmental catalysts using microwave techniques are provided for enlightening the future of this field of research. © 2023 The Author(s)

The identification or design of biocatalysts to mitigate the accumulation of plastics, including sub-micro- and nano-sized polyethylene terephthalate (nPET), is becoming a global challenge. Here we computationally incorporated two hydrolytic active sites with geometries similar to that of Idionella sakaiensis PET hydrolase, to fragaceatoxin C (FraC), a membrane pore-forming protein. FraCm1/m2 could be assembled into octameric nanopores (7.0 nm high × 1.6–6.0 nm entry), which deconstructed (40 °C, pH 7.0) nPET from GoodFellow, commodities and plastic bottles. FraCm1 and FraCm2 degrade nPET by endo- and exo-type chain scission. While FraCm1 produces bis(2-hydroxyethyl) terephthalate as the main product, FraCm2 yields a high diversity of oligomers and terephthalic acid. Mechanistic and biochemical differences with benchmark PET hydrolases, along with pore and nPET dynamics, suggest that these pore-forming protein catalytic nanoreactors do not deconstruct macro-PET but are promising in nanotechnology for filtering, capturing and breaking down nPET, for example, in wastewater treatment plants. [Figure not available: see fulltext.]. © 2023, The Author(s).

[EN] Over the past decades Raman spectroscopy has been extensively used both on an industrial and academic level. This has resulted in the development of numerous specialized Raman techniques and Raman active products, which in turn has led to the adoption and development of standards and norms pertaining to Raman unit’s calibration, performance validation, and interoperability. Purpose of the present review is to list, classify, and engage in a comprehensive analysis of the different standards, guides, and practices relating to Raman spectroscopy. Primary aim of the review is to consider the commonalities and conflicts between these standards and norms and to identify any missing aspects. Standardization in the field of Raman spectroscopy is dominated by the work of American institutions, namely, the American Society of Testing Materials (ASTM or ASTM International), with several active standards in place pertaining to terminology, calibration, multivariate analysis, and specific applications, and the National Institute of Standards and Technology (NIST), providing numerous certified reference materials, referred to as standard reference materials. The industrial application of Raman spectroscopy is dominated by the pharmaceutical industry. As such, pharmacopoeias provide not only important information in relation to pharmaceutical-related applications of Raman spectroscopy, but also invaluable insight, into the basic principles of Raman spectroscopy and important aspects that include calibration, validation, measurement, and chemometric analysis processes, usually by referring to ASTM and NIST standards. Given the fact that Raman spectroscopy is a modern and innovative field, the standardization processes are complex and constantly evolving. Despite the seemingly high number of existing standards, the standardization landscape is incomplete and has not been modernized according to the developments in Raman spectroscopy techniques in recent years. This is evident b

Microplastics (MPs) are a widely recognized global problem due to their prevalence in natural environments and the food chain. However, the impact of microplastics on human microbiota and their possible biotransformation in the gastrointestinal tract have not been well reported. To evaluate the potential risks of microplastics at the digestive level, completely passing a single dose of polyethylene terephthalate (PET) through the gastrointestinal tract was simulated by combining a harmonized static model and the dynamic gastrointestinal simgi model, which recreates the different regions of the digestive tract in physiological conditions. PET MPs started several biotransformations in the gastrointestinal tract and, at the colon, appeared to be structurally different from the original particles. We report that the feeding with microplastics alters human microbial colonic community composition and hypothesize that some members of the colonic microbiota could adhere to MPs surface promoting the formation of biofilms. The work presented here indicates that microplastics are indeed capable of digestive-level health effects. Considering this evidence and the increasing exposure to microplastics in consumer foods and beverages, the impact of plastics on the functionality of the gut microbiome and their potential biodegradation through digestion and intestinal bacteria merits critical investigation.

[EN] Low-energy wet milling was employed to activate commercial CoAl2O4 spinel and disperse mono- and multimetallic nanoparticles on its surface. This method yielded efficient Pt,Ni catalysts for soot oxidation in simulated diesel exhaust conditions. The characterization and activity results indicated that although Ni/CoAl2O4 was highly active, the presence of Pt was required to obtain a stable Ni(0.25 wt. %),Pt(0.75 wt. %)/CoAl2O4 catalyst under the operating conditions of diesel particulate filters, and that hot spots formation must be controlled to avoid the deactivation of the cobalt aluminate. Our work provides important insight for new design strategies to develop high-efficiency low-cost catalysts. Platinum-containing multimetallic nanostructures could efficiently reduce the amount of the costly, but to date non-replaceable, Pt noble metal for a large number of industrially important catalytic processes

[EN] The esterification of rac-ibuprofen and rac-ketoprofen with glycerol catalyzed with the commercial biocatalyst Novozym® 435 was investigated at 45 °C with various profen: glycerol molar ratios using 2-propanol as co-solvent in a batch type reaction. The conversion of rac-ibuprofen reached 46%, with an enantiomeric excess towards the S-enantiomer of 42%. When 1:4 ibuprofen:glycerol molar ratio was assayed, 75% of the R-ibuprofen reacted with glycerol towards the monoglyceride with 99% selectivity, which is highly relevant in the field of prodrugs synthesis. The conversion of rac-ketoprofen was lower, 17 % vs. 46 % of rac-ibuprofen, and the esterification afforded both the monoglyceride (70%) and diglyceride (30%) regardless of the ketoprofen:glycerol molar ratio. Investigations of the esterification at molecular level through concentration-modulated infrared spectroscopy, static ATR-FTIR and in situ Raman spectroscopy showed the continuous decay of the species belonging to rac-ibuprofen and glycerol providing further evidences of the reaction. Moreover, the interaction of CALB with ibuprofen modifies the contribution of the ordered structures of the lipase, which might be related with the improved catalytic performance in the esterification of that profen.

A unique 1D nanostructure of Pt@CeO2-BDC was prepared from Pt@CeBDC MOF. The Pt@CeO2-BDC was rich in oxygen vacancies (i.e., XPS O-beta/(O-alpha + O-beta) = 39.4%), and on the catalyst, the 2 nm Pt clusters were uniformly deposited on the 1D mesoporous polycrystalline CeO2. Toluene oxidation was conducted in a spectroscopic operando Raman-online FTIR reactor to elucidate the reaction mechanism and establish the structure-activity relationship. The reaction proceeds as follows: (I) adsorption of toluene as benzoate intermediates on Pt@CeO2-BDC at low temperature by reaction with surface peroxide species; (II) reaction activation and ring-opening involving lattice oxygen with a concomitant change in defect densities indicative of surface rearrangement; (III) complete oxidation to CO2 and H2O by lattice oxygen and reoxidation of the reduced ceria with consumption of adsorbed oxygen species. The Pt clusters, which mainly exist as Pt2+ with minor amounts of Pt-0 and Pt4+ on the surface, facilitated the adsorption and reaction activation. The Pt-CeO2 interface generates reduced ceria sites forming nearby adsorbed peroxide at low temperature that oxidize toluene into benzoate species by a Langmuir-Hinshelwood mechanism. As the reaction temperature increases, the role of lattice oxygen becomes important, producing CO2 and H2O mainly by the Mars-van Krevelen mechanism.

La invención se refiere a un catalizador para la combustión de hollín que comprende un óxido de fórmula CoAl2O4 en forma de partículas de superficie rugosa, que tiene fase de espinela y defectos extendidos a lo largo de las siguientes facetas de cristal (111), (220), (400) y (311), en donde las partículas tienen una distribución de tamaños de entre 20 nm y 220 nm. Además, la invención se refiere a su proceso de obtención mediante molienda de bolas y su uso para la combustión de hollín

A unique 1D nanostructure of Pt@CeO2-BDC was prepared from Pt@CeBDC MOF. The Pt@CeO2-BDC was rich in oxygen vacancies (i.e., XPS O-beta/(O-alpha + O-beta) = 39.4%), and on the catalyst, the 2 nm Pt clusters were uniformly deposited on the 1D mesoporous polycrystalline CeO2. Toluene oxidation was conducted in a spectroscopic operando Raman-online FTIR reactor to elucidate the reaction mechanism and establish the structure-activity relationship. The reaction proceeds as follows: (I) adsorption of toluene as benzoate intermediates on Pt@CeO2-BDC at low temperature by reaction with surface peroxide species; (II) reaction activation and ring-opening involving lattice oxygen with a concomitant change in defect densities indicative of surface rearrangement; (III) complete oxidation to CO2 and H2O by lattice oxygen and reoxidation of the reduced ceria with consumption of adsorbed oxygen species. The Pt clusters, which mainly exist as Pt2+ with minor amounts of Pt-0 and Pt4+ on the surface, facilitated the adsorption and reaction activation. The Pt-CeO2 interface generates reduced ceria sites forming nearby adsorbed peroxide at low temperature that oxidize toluene into benzoate species by a Langmuir-Hinshelwood mechanism. As the reaction temperature increases, the role of lattice oxygen becomes important, producing CO2 and H2O mainly by the Mars-van Krevelen mechanism.

A unique 1D nanostructure of Pt@CeO2-BDC was prepared from Pt@CeBDC MOF. The Pt@CeO2-BDC was rich in oxygen vacancies (i.e., XPS O-beta/(O-alpha + O-beta) = 39.4%), and on the catalyst, the 2 nm Pt clusters were uniformly deposited on the 1D mesoporous polycrystalline CeO2. Toluene oxidation was conducted in a spectroscopic operando Raman-online FTIR reactor to elucidate the reaction mechanism and establish the structure-activity relationship. The reaction proceeds as follows: (I) adsorption of toluene as benzoate intermediates on Pt@CeO2-BDC at low temperature by reaction with surface peroxide species; (II) reaction activation and ring-opening involving lattice oxygen with a concomitant change in defect densities indicative of surface rearrangement; (III) complete oxidation to CO2 and H2O by lattice oxygen and reoxidation of the reduced ceria with consumption of adsorbed oxygen species. The Pt clusters, which mainly exist as Pt2+ with minor amounts of Pt-0 and Pt4+ on the surface, facilitated the adsorption and reaction activation. The Pt-CeO2 interface generates reduced ceria sites forming nearby adsorbed peroxide at low temperature that oxidize toluene into benzoate species by a Langmuir-Hinshelwood mechanism. As the reaction temperature increases, the role of lattice oxygen becomes important, producing CO2 and H2O mainly by the Mars-van Krevelen mechanism.

[EN] Cobalt aluminate spinel compounds prepared by different methods were characterized in terms of crystallinestructure, morphology, textural properties and acidity, and evaluated as catalysts for diesel soot combustion inNOx/O2mixtures. The activation of commercial CoAl2O4microparticles by ball milling reduced the onsettemperature of this material considerably and yielded an efficient catalyst for soot combustion that exhibited atemperature of half conversion, 411 °C, similar to that obtained with the reference Pt/Al2O3catalyst. Moreover,like Pt, the milled CoAl2O4suppressed the CO formation observed in non-catalytic soot combustion. The sig-nificant modification of the particle size, the emergence of new exposed crystal facets and the creation of defectsare responsible for the appearance of new active sites and high acidity that improved catalyst-to-soot contact andreactivity. Thefindings open a new gate toward the use of efficient Pt-free catalyst for soot combustion.

[EN] Catalytic bodies for selective reduction of NO with NH based on MnO, TiO and sepiolite as active phase, support, and binder, respectively, were prepared. The same amount of MnO (5 w%) was added by impregnation of the precursor over a 70/30 titania/sepiolite. One catalyst was obtained by wet equilibrium impregnation of the pre-shaped support, while the other was prepared by incipient wetness impregnation of the TiO and then mixed with the binder and the PGA, and finally extruded. In order to study the role of the binder in the catalytic system, four models were also synthesized. According to characterization data and to catalytic activity results, sepiolite not only confers the rheological properties needed for extrusion, but it also modifies the physicochemical properties of the catalysts: it modulates the acidity and the NO adsorption capacity and lability, and, depending on the synthesis procedure, it enhances catalytic activity.

The term operando was coined at the beginning of this century to gather the growing efforts devoted to establish structure-activity relationships by simultaneously characterizing a catalyst performance and the relevant surface chemistry during genuine catalytic operation. This approach is now widespread and consolidated; it has become an increasingly complex but efficient junction where spectroscopy, materials science, catalysis and engineering meet. While for some characterization techniques kinetically relevant reactor cells with good resolution are recently developing, the knowledge gained with magnetic resonance and X-ray and vibrational spectroscopy studies is already huge and the scope of operando methodology with these techniques is recently expanding from studies with small amounts of powdered solids to more industrially relevant catalytic systems. Engineering catalysis implies larger physical domains, and thus all sort of gradients. Space- and time-resolved multi-technique characterization of both the solid and fluid phases involved in heterogeneous catalytic reactions (including temperature data) is key to map processes from different perspectives, which allows taking into account existing heterogeneities at different scales and facing up- and down-scaling for applications ranging from microstructured reactors to industrial-like macroreactors (operating with shaped catalytic bodies and/or in integral regime). This work reviews how operando methodology is evolving toward engineered reaction systems.

The assessment of an integral catalytic reactor facilitating operando spectroscopic measurements on a monolith has been carried out using NH3-SCR on a vanadia-based catalyst as a probe reaction. The NH3-SCR mechanism is revisited by studying the adsorbed ammonia and ionically bound ammonium ions and their relations to Lewis and Brønsted acid sites during reaction. The simultaneous presence of molecular water and ammonia adsorbed on the surface is intrinsic to low temperature NH3-SCR, and their IR absorption bands overlap in the bending region around 1600 cm−1. This has to be tackled in order to genuinely reproduce real reaction conditions and simultaneously extract relevant spectroscopic data of a working industrial monolithic catalyst. This operando study on a V2O5-WO3/TiO2–sepiolite monolith is performed without added water in the gas phase, but water formed upstream is adsorbed further down, and thus detected by FTIR spectroscopy. We observed that Multivariate Curve Resolution Alternating Least Squares (MCR-ALS) analysis of the 1620 cm−1 envelope of peaks can successfully resolve the bands of adsorbed H2O and NH3 in the monolith during transients between NH3 and NO + O2 flow. Their evolution along with that of surface ammonium ions indicates that generated water hydrolyzes molecularly dispersed vanadia species of the catalyst creating new Brønsted acid sites, and that adsorbed ammonia is either used for the SCR reaction, or converted into the ammonium ion, which then participates in the SCR reaction.

Structured hybrid materials based on the combination adsorbent-photocatalyst with optimal mechanical resistance and reduced cost, are prepared by extrusion using four different natural silicates with similar mesoporous distribution: sepiolite (S), bentonite (B), mordenite (M) and kaolinite (K). The effect of the textural, morphological and structural properties of plate shaped composites calcined at different temperatures on the adsorption and photocatalytic degradation of formaldehyde in gas phase is analyzed. Silicates allows TiO2 extrusion into flat plates with a content of 50 wt% of titania. All shaped materials present adequate mechanical resistance to be scaled-up for use in continuous-flow gas-phase catalytic reactors. Thermal treatment at 500 °C ensures an optimum combination of mechanical, textural and HCHO adsorption properties. The silicates cover part of the TiO2 particles thus reducing the fraction of TiO2 actually exposed on the surface of the composites, essential to carried out the photocatalytic process, but they also allow controlling TiO2 dispersion and the amount of HCHO adsorbed. The HCHO degradation rate is enhanced with all the silicate-TiO2 composites with respect to that of the benchmark TiO2. The incorporation of titania into the silicate matrix favors the gas phase removal of HCHO in the following sequence: MTi > KTi > STi > BTi > TiO2. The exposed fraction of titania particles and the size of the TiO2-anatase crystalline domains determine the efficiency of the hybrid material, which is optimized in high-aluminum kaolinite and mordenite based hybrids.

Catalysis cannot be understood without spectroscopy, which has to be made during catalytic operation so that we may connect both structure and performance, determining the states and interplay of catalyst sites and reacting molecules. An operando study on powder and shaped vanadium oxide based catalysts is reported to understand selective catalytic reduction of NOx with ammonia (SCR). The SCR process has been employed industrially for decades; it is generally accepted that the reaction follows and Eley‐Rideal type mechanism at 200°C; however the role of NH3 interaction with molecularly dispersed vanadia, and the interplay with water and NOx species is not clearly assessed yet. Raman and infrared spectroscopies provide fundamental molecular information on the states of the catalyst and surface species, while EPR provides additional insight on the states of vanadium species. The combined use of characterization of the catalysts at work provides further insight, but their coupling is complicated by the inherent constraints of each technique, this work will present our progress in understanding powder and honeycomb shaped catalysts, as well as the combination of operando methodologies.

Honeycomb monoliths made up of 70 wt.% sepiolite and 30 wt.% SiC were prepared and macropores were generated in the honeycomb structure by introducing a temporary additive with the aim of obtaining an adequate porosity to use the structures prepared as diesel soot filters (DPF). CLARIMEX activated carbon was the most suitable among the additives studied. In order to generate wall-flow type filters, it was also necessary to investigate suitable materials to alternatively plug the channels of the honeycomb monolith, finding that refractory mortar finely milled and mixed with water formed a paste easy to apply, which adhered firmly to the walls of the monolith being thermally and mechanically resistant. The incorporation of Co and Ce as active phases was performed by successive impregnation followed by calcination at 600 °C. This system presented satisfactory results with respect to the maximum temperature of soot combustion rate, which is in the range of the diesel exhaust gases temperature (300–450 °C). The wall-flow catalytic monoliths developed have similar characteristics to commercial diesel particulate filters in spite of having 70 wt.% of natural clay in its composition. The pore size remains to be further modulated in order to achieve a better permeation flow, similar to that of commercial filters, which could be tried out using larger particle size activated carbons.

Commercially available transparent polymers are evaluated as support for photoactive TiO2 and tested for their application in gas phase photocatalytic oxidation processes. The polymers were selected on the basis of their optical properties and the TiO2 film adhesion. Two low-temperature surfactant-mediated sol–gel synthesis methods of TiO2–SiO2 nanocomposites are investigated to provide acid TiO2–basic SiO2 interactions for the formation of photocatalytic films of higher quality. These procedures are expected to improve photocatalytic properties compared to those obtained by direct coating of TiO2 on the polymers. One method consists in modifying the polymer surface with a layer of poly(diallyldimethylammonium) chloride, which provides a positively charged surface for the fixation of the alkaline SiO2 sol. The other method is based on reducing the surface tension of the SiO2 sol using perfluorobutane sulfonates. Both methods are compared to direct deposition in terms of homogeneity of the layers and photocatalytic activity for trichloroethylene oxidation. Among the commercial polymers employed poly(methyl methacrylate) processed by sheet moulding showed the best optical properties, TiO2 adhesion, and photocatalytic activity, which was promoted by the deposition of the silica interlayer by both preparation methods.

The catalytic oxidation activity of structured macro/mesoporous Pt catalysts obtained by the one-step impregnated carbon procedure (ICP) with different binder/support combinations (sepiolite or mixtures with TiO2 or Al2O3) is compared to that of catalysts with the same composition obtained by conventional impregnation of the previously shaped support, with and without activated carbon as pore-generating agent. The superior results of the former are explained in terms of porosity and metal dispersion, estimated by calculation of the platinum apparent molar surface coverage from electrophoretic migration measurements. The big macropores generated reduce the internal diffusion limitations, facilitating the accessibility of the gaseous compounds to the active phase. However, the main improvement for these sepiolite-based monoliths must be mainly attributed to the good Pt dispersion obtained by this method, with metal particles smaller than 10 nm, confirming the role of the activated carbon template not only as a macroporosity generating agent, but also as a dispersant and stabilizer of the metal particles – preventing agglomeration – and as source of CO for in situ reduction of the precursor. In addition, the ICP method minimizes the calcination steps needed for the preparation of the catalyst.

Hybrid materials composed by natural clays and titanium dioxide (TiO2/clay=50/50) were prepared and tested for NOx photocatalytic degradation. 29% NOx conversion was achieved with the hybrid containing Spanish sepiolite. Among Brazilian clays, a montmorillonite presented the highest conversion of NOx (18%).

ZnO presents favorable thermodynamics, equilibrium constant and stability for H2S chemisorption and sepiolite has excellent sorptive and rheological properties to be employed as a support. Four conformed ZnO/sepiolite composites are prepared, two by impregnation in zinc nitrate solution – one using activated carbon as a dispersing and pore generating agent – and two by dry mixing of the clay with dispersed or hierarchically assembled ZnO nanoparticles. The extrudates obtained with a mixture of sepiolite and nanodispersed ZnO particles are the most active for H2S chemisorption in temperature-programmed tests performed in an inert atmosphere, which can be correlated with the higher and homogeneous ZnO dispersion. ZnO sulfidation is reversible in the presence of O2. Thus, the activity can be regenerated, and these materials act as catalysts for H2S to SO2 oxidation in air.

Wall-flow monolithic filters are commonly made of silicon carbide or cordierite and present high porosity, but low surface area. Alternatively, wall-flow monoliths with high surface area can be employed as support for active phases that catalyze the elimination of the particles deposited in the pores. In this study, mesoporous monoliths with tailored macroporosity are obtained by extrusion using sepiolite clay and different pore generating agents. Cobalt, barium and potassium were incorporated as active phases during the kneading of the dough or by impregnation of the structured material to give the monoliths the capacity for catalytically burning soot under the conditions of diesel engine exhausts. The incorporated and impregnated catalytic monoliths were morphologically, mechanically and physical-chemically characterized at different preparation stages to study the influence of support porosity and the method of addition of active phases in the catalytic activity for diesel soot combustion. The most active catalyst was obtained impregnating the active components to a previously extruded monolith calcined at 850 °C, and then calcining the assembly at 600 °C, for which the temperature of maximum soot combustion rate was 385 °C.

A new monolithic reactor for operando Raman spectroscopy studies of honeycomb-shaped catalysts has been developed to obtain complete information on these systems, considering the effect of conformation on structure–activity relationships; this is illustrated by Raman-GC monitoring of alumina-supported vanadium phosphorous oxide phases during propane ammoxidation with monolithic and powdered beds.

This work is aimed to select the best synthetic polymers available in the market with high transmittance in the TiO2 activation range that can be coated with the semiconductor and withstand the photocatalytic oxidation conditions. Among eleven commercial organic polymers with different additives and processing techniques, only polypropylene, polystyrene, sheet moulding processed poly (methyl methacrylate) and rigid polyvinyl chloride presented transmittances higher than 80% at 360 nm , which allows irradiation there through. The selected polymers were coated without a calcination step with anatase-TiO2 obtained by sol-gel. Their weathering was studied during 150 days of exposure to solar radiation, with and without the TiO2 layer. It was observed that only poly (methyl methacrylate) retains the titania and the good optical and mechanical properties after the natural weathering, and thus is the best candidate for immobilization of TiO2 for air photocatalytic treatment applications., Ministerio de Ciencia e Innovación(España), Depto. de Nutrición y Ciencia de los Alimentos, Fac. de Farmacia, TRUE, pub

Malodor is an important class of air pollution that poses a serious threat to personal health and quality of life. Ammonia gas is a major cause of malodor complaints and is produced by microbial decompositions of organic wastes. A catalyst capable of attaining better than 99 % conversion of 50 ppm NH3 in air at room temperature was successfully prepared. The EA of the reaction is dramatically decreased by using the catalysts when the ratio of VOx/TiOx increases. The NH3 was oxidized to nitrogen and water during the reaction without producing NOx. The catalyst was characterized by BET, micro-Raman and X-ray photoelectron spectroscopy to identify the active sites to be monomeric VOx on TiOx. © Copyright American Institute of Chemical Engineers. All rights reserved.

Malodor is an important class of air pollution that poses a serious threat to personal health and quality of life. Ammonia gas is a major cause of malodor complaints and is produced by microbial decompositions of organic wastes. A catalyst capable of attaining better than 99 % conversion of 50 ppm NH3 in air at room temperature was successfully prepared. The EA of the reaction is dramatically decreased by using the catalysts when the ratio of VOx/TiOx increases. The NH3 was oxidized to nitrogen and water during the reaction without producing NOx. The catalyst was characterized by BET, micro-Raman and X-ray photoelectron spectroscopy to identify the active sites to be monomeric VOx on TiOx. © Copyright American Institute of Chemical Engineers. All rights reserved.

Malodor is an important class of air pollution that poses a serious threat to personal health and quality of life. Ammonia gas is a major cause of malodor complaints and is produced by microbial decompositions of organic wastes. A catalyst capable of attaining better than 99 % conversion of 50 ppm NH3 in air at room temperature was successfully prepared. The EA of the reaction is dramatically decreased by using the catalysts when the ratio of VOx/TiOx increases. The NH3 was oxidized to nitrogen and water during the reaction without producing NOx. The catalyst was characterized by BET, micro-Raman and X-ray photoelectron spectroscopy to identify the active sites to be monomeric VOx on TiOx.

Malodor is an important class of air pollution that poses a serious threat to personal health and quality of life. Ammonia gas is a major cause of malodor complaints and is produced by microbial decompositions of organic wastes. A catalyst capable of attaining better than 99 % conversion of 50 ppm NH3 in air at room temperature was successfully prepared. The EA of the reaction is dramatically decreased by using the catalysts when the ratio of VOx/TiOx increases. The NH3 was oxidized to nitrogen and water during the reaction without producing NOx. The catalyst was characterized by BET, micro-Raman and X-ray photoelectron spectroscopy to identify the active sites to be monomeric VOx on TiOx. © Copyright American Institute of Chemical Engineers. All rights reserved.

Malodor is an important class of air pollution that poses a serious threat to personal health and quality of life. Ammonia gas is a major cause of malodor complaints and is produced by microbial decompositions of organic wastes. A catalyst capable of attaining better than 99 % conversion of 50 ppm NH3 in air at room temperature was successfully prepared. The EA of the reaction is dramatically decreased by using the catalysts when the ratio of VOx/TiOx increases. The NH3 was oxidized to nitrogen and water during the reaction without producing NOx. The catalyst was characterized by BET, micro-Raman and X-ray photoelectron spectroscopy to identify the active sites to be monomeric VOx on TiOx.