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Thermokinetics of Biochar production.

Herein, we report a Nb/ZnO nanocatalyst for the efficient conversion of levulinic acid, a platform molecule easily obtained from lignocellulosic biomass, to N-heterocycles under mild reaction conditions and the absence of solvent. Nb/ZnO nanocatalysts were synthesized by a mechanochemical-assisted and sacrificial template method, involving orange peel valorization toward nanostructured materials. Two different synthetic approaches, either one-step or two-step, as well as the amount of niobium deposited onto the ZnO support were investigated in order to obtain the nanocatalyst with the optimal catalytic properties. Results revealed the critical role of the niobium for LA conversion. The nanocatalyst containing 10 wt% of niobium and prepared following a two-step approach (10 %Nb/ZnO_2) exhibited the best catalytic performance with a 94.5% of conversion and 97.4% of selectivity towards one specific N-heterocycle compound. This work exemplifies the possibility of sustainable production of value-added compounds, in particular N-heterocycles, from biomass-derived feedstocks by playing with the design of improved catalysts. Importantly, this research area provides sustainable alternatives to the current chemical industry that is heavily dependent on fossil fuels.

The use of a biorefinery co-product, such as humins, in combination with an iron precursor in a solvent-free method yields a catalytic material with potential use in selective oxidative cleavage reactions. In particular, this catalyst was found active in the hydrogen-peroxide assisted oxidation of a naturally extracted molecule, isoeugenol, to high added-value flavouring agent, vanillin. By carrying out the reaction in continuous flow, not only a better understanding of the reaction mechanism and of the catalyst deactivation can be achieved, but also important insights for optimised conditions can be developed. The findings of this paper could pave the way to a more sustainable process for the production of a valuable food and perfume additive, vanillin.

Mesoporous silica materials (Al-SBA-15 and Al-MCM-41) were successfully doped with two different transition metals (Zr and Fe) by following a mechano-chemical approach. Different metal precursors (metal salts versus MOF particles) were studied in order to explore their impact on the ultimate catalytic performance of the doped materials. Importantly, doping levels as low as

Recently, green chemistry for the development of sustainable production systems requires tremendous research efforts on the design of catalysts through resource-efficient ways. The improvement of their catalytic performances is a key goal in modern society. Several approaches using environmentally friendly chemicals and materials for less hazardous synthesis and catalysis were analyzed. In this review, we focus on the synthesis of nanomaterials and catalytic applications to reduce the environmental impact, especially, by reducing waste, solvents, precursors, and derivatives. In addition, we highlight the special efforts toward the use of renewable feedstocks and their applications as well as the synthetic routes to develop nanocatalysts using a greener chemistry.

One of the biggest challenges of current times is to reduce the global dependence on fossil fuels. In this scenario, several approaches have been taken to implement efficient processes of biofuel generation from lignocellulosic materials. Here, some of the most recent relevant results are presented. The waste valorization, design of new/more efficient catalysts, the improvement of characteristics by genetic engineering organisms, and the development of new and/or step integration processes, among other possibilities, are important tools to increase and make more relevant the role of renewable fuels in the global energy matrix.

The present work deals with the extraction of phenolic compounds from biomass through microwave-assisted processes. In this case, green walnut shell residues have being studied for the extraction o...

Various international perspectives from selected regions where substantial work is being done on green and sustainable chemistry education emphasize a systems thinking framework. Common to most of the perspectives is the inclusion of more global paradigms involving economic, environmental, political, and social aspects as fundamental issues in the formerly merely technical and scientific discussions, as well as the development of laboratory experiences, training sessions, written materials, discussion meetings, and conferences. We include bird’s eye views from Europe (the Green Chemistry Centre of Excellence at the University of York, United Kingdom; the University of Cordoba, Spain; and the University of Amsterdam, The Netherlands), Latin America (the Universidad Nacional de Rosario, Argentina, and the Universidad Iberoamericana, Mexico), Africa (the University of Venda, South Africa), and Australia (Monash University).

Environmental harmful effects of spent coffee in stream waters pushed our research group to find new applications for this waste material. A new family of magnetic nanocatalysts was synthesized bas...

The mechanochemical incorporation of catalytically active Al species in low loadings was successfully accomplished into the framework of mesoporous silica (SBA-15 and MCM-41) materials using a simple wet milling approach (with aluminum isopropoxide as source of aluminum) and a dry milling approach (using low quantities of Al-containing MOF materials). Characterization data pointed to the successful incorporation of Al species (typically with loadings of ca. 0.2–0.4 wt %) that were mostly tetrahedrically coordinated. Despite such extremely low loadings, the isolated aluminum oxide species exhibited promising activities and stability in selective mild oxidations under various conditions (microwave irradiation and mechanochemistry), including the selective oxidation of benzyl alcohol to benzaldehyde, isoeugenol to vanillin, and diphenyl sulfide to diphenyl sulfoxide, as compared to similarly synthesized impregnated catalysts.

Polypyrrole-modified iron oxide nanomaterials have been synthesized employing a one-step hydrothermal protocol. The influence of the reaction temperature has been investigated by performing the synthesis at four different temperatures (Ppy@Fe2O3-120 °C, Ppy@Fe2O3-140 °C, Ppy@Fe2O3-160 °C, and Ppy@Fe2O3-180 °C). Synthesized materials exhibited an unprecedentedly peculiar morphology (star/coral reef-like architectures), induced by the presence of pyrrole in the reaction media. Full characterization of the samples revealed the critical influence of temperature on the crystallinity, textural properties and specially on (C+N)/Fe surface ratios in the materials. As-synthesized nanohybrids were integrated into electrodes to construct supercapacitor devices. A effective tuning of the electrochemical features was achieved by controlling the (C+N)/Fe ratio on the surface, strongly dependent on reaction temperature. The best electrochemical performance was reached by Ppy@Fe2O3-180 °C nanohybrid, which exhibited a re...

A highly sustainable method for the preparation of supported iron oxide and copper nanoparticles (NPs) on a biomass-derived carbon by solvent-free mechanochemical process is reported. In-situ mechanochemically obtained extracts from orange peel could behave as a green reducing agent, allowing the formation of Cu metal nanoparticles as well as generating a magnetic phase (magnetite) in the systems via partial Fe3+ reduction. At the same time, orange peel residues also served as template and carbon source, adding oxygen functionalities, which were found to benefit the catalytic performance of mechanochemically synthesized nanomaterials. The series of magnetic Cu-Fe@OP were tested in the oxidation of trans-ferulic acid towards vanillin, remarkably revealing a maximum vanillin yield of 82% for the sample treated at 200 °C.

A perspective on the use of heterogeneous catalysis to drive the waste-to-pharma concept is provided in this contribution based on the conversion of furanics to active pharmaceutical ingredients (APIs). The provided overview of the concept in this perspective article has been exemplified for two key molecule examples: Ancarolol and Furosemide.

In this work, we report the incorporation of nickel oxide nanoparticles into a metal–organic framework (MOF) structure by a solvent-free mechanochemical strategy. In particular, the zirconium-based MOF UiO-66 was modified with different Ni loadings and characterized using complementary techniques including X-ray diffraction (XRD), N2 porosimetry and X-ray photoelectron spectroscopy (XPS). The catalytic potential of the as-prepared Ni/UiO-66 materials in the hydrogenation reaction of methyl levulinate using 2-propanol as hydrogen donor solvent has been investigated under flow conditions. Under optimized conditions, the 5%Ni/UiO-66 led to the best catalytic performance (70% yield, 100% selectivity to gamma-valerolactone), which could be attributed to the higher content of the Ni species within the MOF structure. The obtained results are promising and contribute to highlighting the great potential of MOFs in biomass upgrading processes, opening the path to the sustainable development of the chemical industry.

Research on biomass valorization approaches demands endeavors from the scientific community, looking forward to more sustainable and renewable alternatives to the petro-based industry. In this regard, the group FQM-383 (NANOVAL), from University of Cordoba has dedicated many efforts, going from conventional heating approaches to continuous flow strategies, and to the use of unconventional technologies such as microwave and ultrasound irradiations. Moreover, investigations on biomimetic catalysis and photocatalysis have been also directed to the upgrading a biomass residues and derived platform molecules. Importantly, the investigations performed by our research group consider atom, cost and energy efficiency of a process, involving renewable feedstocks and catalytic steps.

In this work, we present the green Ni-MOF modification by the mechanochemical process in the solvent-free route that has been prepared as hydrogenation catalyst. The zirconium-based metal-organic framework UiO-66 (MOF) at different loading of Ni, were characterized using different techniques including X-ray diffraction (XRD), N2 porosimetry, X-ray photoelectron spectroscopy (XPS), have been employed for the characterization of the structural, textural, and composition properties of the synthesized materials, respectively. The catalysts have been evaluated in the hydrogenation reaction of methyl levulinate using 2-propanol as a hydrogen donor solvent. The reaction conditions were investigated and established at 30 bar system pressure with a reaction temperature of 200 ◦C using around 0.1 g of catalyst and a flow rate of 0.2 mL/min flow rate of a 0.3 M methyl levulinate solution in 2-propanol. All catalysts employed in this work exhibited good catalytic activities under the investigated conditions, with conversion values in the 30-70% range the selectivity to Υ-valerolactone was 100% for all samples (after one hour time on stream). The highest methyl levulinate conversion and selectivity was achieved by MOF-Ni5% which can be explained by the higher dispersion content of Ni species and the highest accessibility of the Zr sites of the MOF structures even when the superficial area has been reduced.

In the present work, the extraction and characterization of polysaccharides derived from bay tree pruning waste and their upgrading into methyl levulinate (MLA) are reported. The extraction was car...

The effective design of an active and stable catalytic system was performed by a simple modification of a commercial titania with a low platinum loading. The prepared material was fully characterized by XRD, XPS, N2 adsorption–desorption measurements, ICP-MS, TEM and SEM analyses. Such techniques corroborated the successful incorporation of Pt onto the titania surface, without affecting its original structure, morphology and chemical nature. The obtained TiO2–Pt catalyst was effectively applied in several continuous flow reactions between nitriles and carbonyl containing compounds for amine preparation. Remarkably, conversion of levulinic acid, a biomass derived molecule, was achieved with outstanding conversion (87%) and selectivity (80%) to 1-ethyl-5-methylpyrrolidin-2-one. The catalytic system demonstrated a high stability through 120 min of reaction. Moreover, the effect of the nitrile was investigated by performing the reaction with benzonitrile and ethylcyanoacetate. The TiO2–Pt catalyst was also tested in the conversion of benzaldehyde, displaying remarkable results. The influence of substitution in the aromatic ring was investigated using p-nitro-benzaldehyde and p-chloro-benzaldehyde.

A carbonaceous material with desirable properties for lithium-ion batteries (LIBs) was successfully obtained using a low cost and eco-environmental approach based on the mechanochemical dry milling of spent coffee grounds (SCG) followed by further carbonization at 800 °C. The spent coffee grounds derived carbon material (C-SCG) was employed as anodic material delivering a specific capacity of 360 mAh g−1 in the second cycle at current density of 0.1 A g−1. Additionally, the C-SCG material exhibited a competitive anode performance with a reversible capacity of 285 mAh g−1 and a remarkable coulombic efficiency nearly to 100% from the 2nd cycle. The resulting LIBs showed remarkable capacities retention over 100 cycles with a decay rate per cycle of 0.23%. This work contributes to the development of eco-environmental batteries using low-cost materials as a promising solution for increasing energy storage demands.

A new eco-friendly approach for the preparation of sustainable heterogeneous palladium catalysts from rice husk-derived biogenic silica (RHP-Si and RHU-Si). The designed heterogeneously supported palladium species (RHP-Si-NH2-Pd and RHU-Si-NH2-Pd) were fully characterized and successfully employed as catalysts for various chemical transformations (C–C bond-forming reactions, aerobic oxidations and carbocyclizations). Suzuki-Miyaura transformations were highly efficient in a green solvent system (H2O:EtOH (1:1) with excellent recyclability, providing the cross-coupling products with a wide range of functionalities in high isolated yields (up to 99%). Palladium species (Pd(0)-nanoparticles or Pd(II)) were also efficient catalysts in the green aerobic oxidation of an allylic alcohol and a co-catalytic stereoselective cascade carbocyclization transformation. In the latter case, a quaternary stereocenter was formed with excellent stereoselectivity (up to 27:1 dr).

Supported Co3O4 nanoparticles on SBA-15 aluminosilicates (Al-SBA-15) with different cobalt loadings (0.5, 1, 5, 10 wt %) were synthesized by ball-milling. The synthesized materials were characterized by different techniques including, N2 adsorption measurements, XRD, TEM, EDX, ICP-MS, DRIFTs of pyridine among others. The catalysts were studied in the microwave assisted benzyl alcohol oxidation as well as in the akylation of toluene with benzyl chloride. Co3O4 catalysts exhibited moderate conversions in the selective oxidation of benzyl alcohol, with a high selectivity towards benzaldehyde. Lewis acidity increases upon the incorporation of cobalt nanoparticles onto the surface of the support which was found to significantly influence the materials in the alkylation of toluene with benzyl chloride. The high active sites accessibility of ball-milling prepared materials leads to high conversions to alkylated derivatives in short periods of time (>99 mol %, 30 min). A direct correlation acidity/activity could not be obtained in the systems, for which nanoparticle sizes and distribution could influence the observed activities.

In this work, two different strategies have been employed to explore the potential valorization of biomass waste. A TiO2-based sample was prepared by a dry-milling strategy, involving orange peel valorization toward nanostructured materials. Subsequently, ruthenium deposition was accomplished by a chemical reduction method to obtain different ruthenium loadings on the titania support. The prepared catalysts were characterized using a multitechnique approach in terms of chemical, structural, and morphological properties. Levulinic acid, a typical model molecule associated with lignocellulosic biomass, was subsequently converted into N-heterocycles in a continuous flow reactor. The prepared Ru-TiO2 systems exhibited outstanding catalytic performance in terms of conversion and selectivity in comparison with Ru/P25 and Ru/C catalytic references. Maximum activity (79% conversion, 85% selectivity to 1-ethyl-2-(ethylideneamino)-5-methylpyrrolidin-2-ol) was achieved for the sample containing 3 wt % Ru, homogeneou...

The conversion of the biomass-derived lipid, lignocellulosic and carbohydrate resources into renewable platform intermediates, chemicals and biofuels has been lately increasing in interest. The mechanistic reaction pathways, like hydro-deoxygenation, decarboxylation and hydrocracking, of the selected palmitic acid, as a model fatty acid, over Ni/ZSM-5 zeolite catalysts were studied. The ZSM-5 material with different Al/Si molar ratios was synthesized via a green template-free hydrothermal synthesis procedure, treated and subsequent functionalised with various Ni metal loadings. However, Ni/Al molar ratio was kept stoichiometric (Ni/Al = 0.5). The characteristic physicochemical properties of composite catalysts were studied by numerous characterization techniques, such as X-ray powder diffraction (XRD), scanning-, as well as high-resolution transmission electron microscopy (SEM/HRTEM), and X-ray photoelectron spectroscopy (XPS). NiO with an average particle size of 10–20 nm was found on ZSM-5 support. The relative Ni/Al atom fraction in Ni/ZSM-5 systems influenced their Lewis/Bronsted acidic sites, as well as the external exposed area of prepared heterogeneous structures. Furthermore, the mentioned morphological parameters affected predominant catalytic routes. Species’ production mechanism, as a consequence of Lewis/Bronsted centre weak/strong acidity, as well as their integral concentration, was proposed, mirroring the observed process kinetics, selectivity and turnover. It was demonstrated that the main obtained products were esters, aldehydes, alcohols, hydrocarbons and gases (CO2, CO…), produced by deoxygenation (e.g. decarbonylation), hydrogenation and cracking, less, though, through isomerisation.

A template-free, simple, effective, and reproducible integrated mechanochemical/microwave promoted methodology has been designed to derive porous silica materials from rice husk waste. Microwave-as...

The efficient electronic wiring of silica-encapsulated laccases has been applied for the first time to the bioelectrocatalytic reduction of oxygen. The synthesized silica/laccase composites were evaluated electrochemically and characterized by UV–vis, Fourier transform infrared (FT-IR), dynamic light scattering, and X-ray photoelectron spectroscopy. FT-IR measurements showed that laccase preserved its native-like structure after the biosilicification process. The one-pot biosilicification synthesis facilitated the accommodation of the enzymes in highly effective orientations for the direct electron transfer of the T1 redox centers. Consequently, the biosilicified laccase deposited on Ni electrodes exhibited an efficient bioelectrocatalytic oxygen reduction, with current densities of up to 0.94 mA/cm2.

En este trabajo se han diseñado experiencias prácticas de Química para ser mostradas en el aula. Asimismo se han seleccionado animaciones sobre de conceptos químicos que hacen muy comprensible el estudio de esta ciencia. Estos recursos se muestran en español y en inglés ya que se pretende que sean de utilidad no solo a los alumnos de Química también para los de Traducción e Interpretación. El trabajo esta estructurado de forma que se aprovecha el potencial de los docentes expertos en materia de Química y de Traducción de Inglés. De esta forma se establece un sinergismo entre asignaturas de ciencias y de traducción especializada, potenciando su efecto en la formación de los estudiantes. El trabajo se ha complementado con el uso de la web 2.0 como soporte de los recursos diseñados y con la creación de una base de datos utilizando moodle para su desarrollo.

The zirconium-based metal organic framework, UiO-66 (Zr), was successfully synthesized via solvothermal method, followed by various characterization including XRD, thermal analysis, N2 physisorption, and TEM. As-synthesized UiO-66 (Zr) was employed in the transformation of methyl levulinate (ML) to γ-valerolactone (GVL) via catalytic transfer hydrogenation (CTH) under continuous flow and various reaction conditions, which gave superior catalytic performance and efficiency as compared to reported catalysts. The obtained results show great potential of applying UiO-66 (Zr) in upgrading biomass derivatives to useful biofuel/chemical products, paving the way for green energy production from renewable resources.

The current needs of finding more efficient materials with tunable properties have served as a motivation for the scientific community to move toward nature-inspired hierarchical materials adhering to the green analytical chemistry principles also because of the high complexity and efficiency of systems in nature. Such type of materials has exhibited highly dynamic interfacial interactions, which are outstandingly valuable for sensing and energy storage applications. Nature-based systems have displayed remarkable features, in terms of energy density, coulombic efficiency behavior, cycling stability energy, durability, and sensitivity. More interestingly, the aforementioned properties could be tuned by modifying the interfacial interactions within the material components. Along this contribution, recent developments on the design of green analytical nature-inspired hierarchical materials will be addressed, especially paying attention to the relationship between interfacial interactions and material features.

Bioconjugates based on a redox protein and iron oxide magnetic nanoparticles were employed in the catalytic polymerization of ortho-, meta- and para-substituted phenylenediamines at room temperature for the synthesis of carbon-based fluorescent polymers. UV-Vis absorption measurements of the three obtained products showed a red shift compared to the starting materials. These results together with the FT-IR and XPS analyses confirm the successful formation of the polymers. In particular, the component quantification in the C 1s XPS spectra revealed the high proportion of C–N bonds, associated with the oxidative polymerization of the precursors. MALDI-TOF MS analysis was performed in order to determine the molecular weights of the products. The synthesized poly-oPDA, poly-mPDA and poly-pPDA resulted to have a highly green, blue and red fluorescence, respectively. The reusability of the biocatalyst and the effect of the pH were investigated in the reaction for the ortho isomer. The biocatalytic system showed optimum results when the pH was below the enzyme isoelectric point (pI).

A biocatalytic system based on laccase functionalized waste-derived iron oxide nanoparticles (LAC-DA-Fe2O3) was designed by a mechanochemical approach and employed in the electrocatalytic reduction of oxygen. Full characterization of the obtained bioconjugates revealed that the protein adopted a partially unfolded state. The mentioned configuration, together with the geometry coordination changes along the T1 center can be further related to a high bioelectrocatalytic response. A current density up to 2.9 mA cm-2 has been achieved, which is among the highest values reported in literature for laccase functionalized nanomaterials.