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Biotemplating technique allows the synthesis of catalysts, recreating the sophisticated structure of nature templates. In this work, some biotemplated TiO2 semiconductors were synthesized using Olea europaea leaves as templates. Then, g-C3N4 was coupled to materials to later incorporate Pt on the surface or as dopant in the structure to evaluate the efficiency of the solids in two photocatalytic applications to valorize biomass: hydrogen production through glycerol photoreforming, and photoacetalization of cinnamaldehyde with 1,2-propanediol. In glycerol photoreforming, the presence of Pt (superficial or dopant) enhanced hydrogen production, being Pt@AOLCN (a heterojunction containing biotemplated TiO2, g-C3N4, and Pt) the system that exhibited the highest efficiency (3053.4 µmol·gcat−1·h−1). For photoacetalization, while Pt reduced cinnamaldehyde conversion, it improved selectivity when incorporated on TiO2. Notably, carbon nitride (CN) exhibited the highest yield after 16 h of testing. The study emphasizes the importance of tailoring catalyst selection to specific reactions, as efficiency is closely tied to the structural and chemical properties of the materials. These findings contribute to the development of efficient photocatalysts for sustainable biomass valorization processes. [ABSTRACT FROM AUTHOR]

Pt-TiO2 systems are the most widely used photocatalysts in the production of green hydrogen from glycerol photoreforming. To incorporate metals on the surface of materials, photodeposition is the most used method because it employs mild conditions. However, despite its use, there are some parameters that have not been deeply studied, such as the appropriate metal loading and the method itself, to obtain a better dispersion of Pt. In this work, six Pt-TiO2 catalysts were synthesized by a classical photodeposition method employing UV radiation. The studied Pt wt.% range was 0.15–0.60 wt.%, being incorporated in one step or in subsequent ones. HRTEM analyses showed that both methods allowed a homogeneous distribution of Pt, and in both, the particle size was around 2.3–3.6 nm, increasing with metal loading. The photocatalytic activity of materials was tested in glycerol photoreforming under UV radiation, and the 0.45 wt.% Pt-containing solid that had been synthesized in one step was the one that allowed the highest hydrogen production. This might suggest that around 0.40% is the appropriate metal loading for hydrogen production under these conditions and that incorporating the desired metal percentage in one step is the most efficient method in terms of energy and time savings. [ABSTRACT FROM AUTHOR]

Several biochars were synthesized from olive stones and used as supports for TiO2, as an active semiconductor, and Pt as a co-catalyst (Pt/TiO2-PyCF and Pt/TiO2-AC). A third carbon-supported photocatalyst was prepared from commercial mesoporous carbon (Pt/TiO2-MCF). Moreover, a Pt/TiO2 solid based on Evonik P25 was used as a reference. The biochars used as supports transferred, to a large extent, their physical and chemical properties to the final photocatalysts. The synthesized catalysts were tested for hydrogen production from aqueous glycerol photoreforming. The results indicated that a mesoporous nature and small particle size of the photocatalyst lead to better H2 production. The analysis of the operational reaction conditions revealed that the H2 evolution rate was not proportional to the mass of the photocatalyst used, since, at high photocatalyst loading, the hydrogen production decreased because of the light scattering and reflection phenomena that caused a reduction in the light penetration depth. When expressed per gram of TiO2, the activity of Pt/TiO2-PyCF is almost 4-times higher than that of Pt/TiO2 (1079 and 273 mmol H2/gTiO2, respectively), which points to the positive effect of an adequate dispersion of a TiO2 phase on a carbonaceous support, forming a highly dispersed and homogeneously distributed titanium dioxide phase. Throughout a 12 h reaction period, the H2 production rate progressively decreases, while the CO2 production rate increases continuously. This behavior is compatible with an initial period when glycerol dehydrogenation to glyceraldehyde and/or dihydroxyacetone and hydrogen predominates, followed by a period in which comparatively slower C-C cleavage reactions begin to occur, thus generating both H2 and CO2. [ABSTRACT FROM AUTHOR]

Hydrogen production is mainly based on the use of fossil fuels, but currently, many alternative routes are being developed, among which the photo-reforming of oxygenated organic compounds stands out. Recently, several studies have been carried out in order to develop new techniques to create bio-inspired TiO2 structures. One of these is 'biotemplating', a process that replicates a biological system in an inorganic TiO2-based structure. In this study, olive by-products—olive leaves—are valorized as a biotemplate for the synthesis of new Fe-TiO2- and Cu-TiO2-based photocatalysts with the aim of improving the replication of the leaf structure and enhancing hydrogen photoproduction. In conclusion, the incorporation of iron and copper decreases the band gap and increases the energetic disorder at the band edges. Moreover, it is verified by SEM and TEM that the metals are not found forming particles but are introduced into the formed TiO2 structure. The accuracy of the internal and external structure replication is improved with the incorporation of Fe in the synthesis, while the incorporation of Cu substantially improves the production of hydrogen, which is multiplied 14 times under UV light and 6 times under sunlight, as compared to a pure TiO2 structure. [ABSTRACT FROM AUTHOR]

Fatty acids are the major compounds in olive oils, and the determination of their profile is very useful in order for the authentication of the high quality of extra virgin olive oil (EVOO) and the evaluation of its purity and traceability. This work considers the estimations of saturated (SAFA), monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids obtained by gas chromatography (GC), 13C (carbonyl, C‐16, and aliphatic carbons regions), and 1H NMR spectra. The aim of this paper is to analyze the correlation structure being between the abovementioned fatty acids estimations and some long‐run agroclimatic measurements (temperature, humidity, wind speed and direction, radiation, precipitation, and evapotranspiration), which were downloaded from the official website of the Andalusian Automatic Weather Stations (AWSs). The versatile graphical possibilities of the free software R‐project allow the design of computational programs providing interesting conclusions about the described correlations as a function of month, variety of olive, and protected designation of origin (PDO). The statistically significant correlations could determine relevant agroclimatic information to be included, in a further research, among the explanatory variables in regression models in order to improve the estimation of fatty acid profile of EVOOs, considered as a quality parameter in their authentication. Fatty acids are the major compounds in olive oils and very useful in order to the authentication of the high quality of extra virgin olive oil (EVOO). This paper analyzes the effect of agroclimatic big fata, instead of a meteorological factor, on EVOO fatty acid profile determined by GC and NMR spectra. The power of the free software R‐project and its versatile graphical possibilities allows the design of computational programs providing interesting conclusions about the described correlations as a function of month, variety of olive, and protected designation of origin (PDO). [ABSTRACT FROM AUTHOR]

Extra virgin olive oil (EVOO) is very appreciated by its taste, flavor, and benefits for health, and so, it has a high price of commercialization. This fact makes it necessary to provide reliable and cost‐effective analytical procedures, such as near‐infrared (NIR) spectroscopy, to analyze its traceability and purity, in combination with chemometrics. Fatty acids profile of EVOO, considered as a quality parameter, is estimated, firstly, from NIR data and, secondly, by adding agro‐climatic information. NIR and agro‐climatic data sets are summarized by using principal component analysis (PCA) and treated by both scalar and functional approaches. The corresponding PCA and FPCA are progressively introduced in regression models, whose goodness of fit is evaluated by the dimensionless root‐mean‐square error. In general, SFAs, MUFAs, and PUFAs (and disaggregated fatty acids) estimations are improved by adding agro‐climatic besides NIR information (mainly, temperature or evapotranspiration) and considering a functional point of view for both NIR and agro‐climatic data. [ABSTRACT FROM AUTHOR]

BACKGROUND Fatty acids are the major components in extra virgin olive oil, and they are considered as a quality parameter to its authentication. As fraudulent practices are the most important problem in this sector, fast, reliable and cost‐effective techniques, such as Raman spectroscopy, have been successfully applied, in combination with chemometrics, to determine the fatty acid profile of oils. RESULTS: The huge amount of information provided by Raman spectra is reduced in a few orthogonal components of principal component analysis (PCA). The goodness‐of‐fit of the statistical models including only these PCA factors is considerably increased by introducing dummy variables, associated with the harvest, and some agro‐climatic variables (temperature, humidity, wind speed, radiation, precipitation and evapotranspiration). Many of these additional variables are statistically relevant in models using either the global sample or subsamples of Andalusian provinces or olive varieties. CONCLUSIONS: The regression models using only Raman spectral information are clearly improved by the consideration of harvesting time and agro‐climatic data, a useful result as trade standard applying to olive oils limits values for disaggregated fatty acids to authenticate olive oils. Nevertheless, the effect (or the statistical relevance) of these variables depends on the specific type of fatty acid, geographical region (province) or olive variety. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Two series of catalysts were prepared by sol-gel and microemulsion synthetic procedure (SG and ME, respectively). Each series includes both pure Mg and Zr solids as well as Mg-Zr mixed solids with 25%, 50% and 75% nominal Zr content. The whole set of catalysts was characterized from thermal, structural and surface chemical points of view and subsequently applied to the liquid-phase xylose dehydration to furfural. Reactions were carried out in either a high-pressure autoclave or in an atmospheric pressure multi-reactor under a biphasic (organic/water) reaction mixture. Butan-2-ol and toluene were essayed as organic solvents. Catalysts prepared by microemulsion retained part of the surfactant used in the synthetic procedure, mainly associated with the Zr part of the solid. The MgZr-SG solid presented the highest surface acidity while the Mg3Zr-SG one exhibited the highest surface basicity among mixed systems. Xylose dehydration in the high-pressure system and with toluene/water solvent mixture led to the highest furfural yield. Moreover, the yield of furfural increases with the Zr content of the catalyst. Therefore, the catalysts constituted of pure ZrO2 (especially Zr-SG) are the most suitable to carry out the process under study although MgZr mixed solids could be also suitable for overall processes with additional reaction steps. [ABSTRACT FROM AUTHOR]

The thermochemical processing of biomass is an alternative route for the manufacture of fuel-grade ethanol, in which the catalytic conversion of syngas to ethanol is a key step. The search for novel catalyst formulations, active sites and types of support is of current interest. In this work, the catalytic performance of an Rh/MCM-41 catalyst has been evaluated and compared with a typical Rh/SiO2 catalyst. They have been compared at identical reaction conditions (280 °C and 20 bar), at low syngas conversion (2.8%) and at same metal dispersion (H/Rh = 22%). Under these conditions, the catalysts showed different product selectivities. The differences have been attributed to the concentration of water vapor in the pores of Rh/MCM-41. The concentration of water vapor could promote the water-gas-shift-reaction generating some extra carbon dioxide and hydrogen, which in turn can induce side reactions and change the product selectivity. The extra hydrogen generated could facilitate the hydrogenation of a C2-oxygenated intermediate to ethanol, thus resulting in a higher ethanol selectivity over the Rh/MCM-41 catalyst as compared to the typical Rh/SiO2 catalyst; 24% and 8%, respectively. The catalysts have been characterized, before and after reaction, by N2-physisorption, X-ray photoelectron spectroscopy, X-ray diffraction, H2-chemisorption, transmission electron microscopy and temperature programmed reduction. [ABSTRACT FROM AUTHOR]