Ordered mesoporous CeO2 has been prepared via a hard-template method using SBA-15 as a structure-directing agent. Leaching with NaOH and thermal treatment at 500 °C enabled the removal of the ...inorganic template, thus resulting in the formation of long-range ordered CeO2. Nevertheless, small amounts of silica were present in the final oxides. The resulting CeO2 samples were used as supports for Au nanoparticles and the prepared catalysts were tested in the selective oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). Fine tuning of the silica template removal process was necessary to prepare active materials, by maximizing the close contact between the metal and the support, and thus confirming the important role of ceria defects in 5-hydroxymethylfurfural oxidation to 2,5-furandicarboxylic acid.
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•CeO2 with high surface area and a controlled morphology has been prepared by nanocasting using SBA-15 as template.•Gold–support interaction is crucial for favoring catalytic activity.•The fine tuning of the silica template removal process leads to the optimization of HMF oxidation to FDCA.
The catalytic conversion of methyl and ethyl levulinates into γ-valerolactone (GVL) by using methanol, ethanol, and 2-propanol as the H-donor/solvent, promoted by the ZrO2 catalyst, is described as ...carried out under both batch and gas-flow conditions. Under batch conditions, 2-propanol was found to be the best H-donor molecule, with ethyl levulinate giving the highest yield in GVL. The reactions occurring under continuous gas-flow conditions were found to be much more efficient, also showing excellent yields in GVL when EtOH was used as the reducing agent. These experiments clearly show that the ability to release hydrogen from the alcoholic H-donor/solvent is the main factor driving CTH processes, while the tendency to attack the esteric group is the key step in the formation of transesterification products.
•Comprehensive kinetic study on V-based catalysts for the ammoxidation of ethanol to acetonitrile.•5 groups of experiments on VOx-based catalysts (T = 250–450 °C).•Kinetic model derived applying the ...Langmuir-Hinshelwood-Hougen-Watson approach (8–10 reactions).•Reaction orders fixed by the mechanistic assumption, kinetic and adsorption parameters adjusted.
A comprehensive kinetic study, based on V-based catalysts (Vanadium Pyro-Phosphate, VPP, VOx/TiO2 and VOx/ZrO2), was modeled to retrieve the surface reaction mechanism and kinetic parameters for the ammoxidation of ethanol to acetonitrile. In all the cases, the catalysts showed a moderate to good acetonitrile selectivity, that in turn resulted correlated primarily to the reaction temperature, while the byproducts distribution was more influenced by the thermodynamic stability of the reacting mixture.
A large and comprehensive collection of data on ammoxidation of C2 substrates for acetonitrile production was analysed and 5 groups of experiments on VOx-based catalysts (operating in the temperature range 250–450 °C) were selected. The base reactant was ethanol and ammonia and oxygen were fed in optimal ratios of 1:3–1:4 mol/mol.
A kinetic model was then derived applying the Langmuir-Hinshelwood-Hougen-Watson (LHHW) approach to accepted catalytic oxidation mechanisms: for every catalytic material, eight to ten reactions with rates described by the Arrhenius formula were employed. Fixing the reaction orders according to the mechanistic assumption and adjusting only the kinetic and adsorption parameters, the calculated molar fractions of ethanol, ammonia, acetonitrile and ethylene resulted in good agreement with the extensive collection of experimental data available.
The usefulness of ketonization reactions for the valorization of a wide plethora of biomass-derived carboxylic acids is widely recognized; however, the full potential of this reaction has yet to be ...suitably exploited for the production of high added-value aromatic and/or aliphatic asymmetric ketones. For this reason, herein we report for the first time in the literature the continuous-flow, gas-phase synthesis of 2-acetyl furan (AF) by means of the catalytic cross-ketonization of bio-based 2-methyl furoate (2-MF) and acetic acid (AA) over a simple and cheap ZrO
2
catalyst. Interestingly, AF is considered a valuable food additive and a pharmaceutical intermediate for the synthesis of antibiotics. The optimization of the molar ratio between reactants at 350 °C allowed us to achieve 87% AF selectivity at 90% 2-MF conversion, with a space-time yield of 0.152 h
−1
, a value that is similar to the ones obtained by following the traditional Friedel-Crafts acylation and Wacker oxidation routes. On the other hand, the
E
-factor of the herein-proposed process is several times lower compared to the aforementioned traditional routes performed in the liquid phase and under batch conditions. Finally, the versatility of the cross-ketonization synthetic approach was successfully demonstrated and applied for the selective synthesis of other valuable acyl furans (
i.e.
, propionyl furan and butyryl furan).
Continuous-flow, gas-phase cross-ketonization of alkyl 2-furoates with bio-based acids toward an alternative, selective production of valuable acyl furan intermediates.
Copper-manganese spinel ferrites have been evaluated as solid oxygen carriers for the production of hydrogen from water by ethanol-steam redox cycles. The materials were characterized by X-ray ...diffraction, Mössbauer spectroscopy, temperature-programmed reduction, oxygen isotope exchange and textural analysis. Surface reactions were followed by DRIFT spectroscopy. The amount and purity of hydrogen, produced in redox cycles at constant temperature of 450 °C, were highly affected by the nature of the oxygen carrier phases in the reduction step of the cycle. Cu-rich ferrites were reduced by ethanol to metallic copper and iron carbides, whereas Mn-rich ferrites were less deeply reduced to manganowustite. Ethanol was mainly oxidized by Cu-ferrites to CO and CO2, while mainly oxydehydrogenation products were formed on Mn-ferrites. In the reoxidation of the oxygen carrier by steam, the production of CO and CO2 by oxidation of carbides negatively affected the purity of the hydrogen formed.
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•Transition-metal ferrites as oxygen carriers for hydrogen production from oxygenates.•The mechanism of reduction of ferrites is controlled by divalent components.•The production of low-carbon ethanol depends on the pathway of ethanol reforming.
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•Cu-Ni mixed oxides effective catalyst of transfer hydrogenolysis of lignin model.•Catalysts from hydrotalcites allow hydrogen transfer from subcritical methanol.•In-situ reduction of ...oxides in reaction medium forms active hydrogen transfer sites.•Preservation of aromatic rings provides valuable lignin depolymerisation products.
Copper and nickel mixed catalysts obtained by calcination of iron and aluminium hydrotalcites (layered double hydroxides, LDH) have been tested in the conversion of a lignin model dimer in subcritical methanol. Phase distribution and textural properties of the catalysts were characterized by X-ray diffraction Rietveld analysis and N2 physisorption. The presence of copper was critical for effective hydrogenation, both by direct hydrogen transfer from methanol to aldehyde groups and by reactivity of products from methanol reforming. TPR experiments showed that the hydrogenation activity was promoted by an enhanced reducibility of the Cu-catalysts, related to the presence of other oxide components.
Characterisation of the catalysts after reaction indicated that metallic copper was formed by the reduction of CuO by methanol and that modifications of the oxide catalysts in the reaction medium played a major role in the formation of active sites.
The aim of this study is to apply the LCA methodology to the industrial chemical sector, in order to compare the traditional process for acrylonitrile production from propylene with alternative ...routes starting from propane, while assessing which one is the cleaner production in terms of sustainability, from a life cycle perspective. The model created refers to the production of 1 kg of acrylonitrile. System boundaries of each scenario include all mass flows into and out of the reactor, all mass and energy flows into and out of the heat exchanger of the fluid bed, the amount of raw material for the production of each catalyst, the avoided impacts resulting from energy and mass recovery, and all transportations. Also, average infrastructure processes that refer to land use, building, and disposal of the chemical plant were not included. The life cycle evaluation was performed using the ReCiPe 2008 method v1.07, showing results in terms of midpoint categories such as Climate Change, Fossil Fuel Depletion, and Metal Depletion. The results from the inventory show that alternative synthetic routes starting from propane have higher impacts than the traditional processes in terms of fossil fuel depletion and climate change categories due to higher consumption of reactants, caused by the lower efficiency of catalytic systems. Conversely, impacts associated with the metal depletion category have an irregular trend, due mainly to the extraction of different percentages of resources for the catalyst production. The results were validated by a sensitivity analysis using the Monte Carlo method. This study suggests that the LCA methodology may be used as a scientific approach to identify the environmental issues associated with the chemical production of a product. In particular, it is useful in comparing alternative ways of synthesis and evaluating which process is more sustainable, and which production stage should be improved in order to ensure greater environmental sustainability.
•Acrylonitrile industrial production was studied through LCA methodology.•The propylene ammoxidation, and the alternatives starting from propane were compared.•Low yield for propane based processes implies higher consumption of reactants.•Higher impacts in terms of climate change and fossil depletion for propane scenario.•Results was confirmed using Monte Carlo statistical method.
The growing interest for new routes to obtain acetonitrile led to the development of catalysts active toward the ammoxidation of various substrates. Among these, a C2 molecule such as ethanol ...represents a good choice in terms of atom economy and, being renewable, sets the basis for a long-term sustainable process. This paper describes a fully integrated, newly designed process for the production of acetonitrile from bioethanol, currently not present in the literature. The target is the production and purification of 10 kg/h of acetonitrile, unit of production used for calculations, obtained from ethanol, ammonia, and air as raw materials. All the byproducts, mainly ammonium bicarbonate and sodium cyanide, are considered marketable chemicals and represent an added value, instead of a disposal issue. Their optimized recovery is included in this flowsheet as a basis for the future economic assessment of the system. The process consumes CO2 without its direct emission. In principle, all the carbon atoms and 90% of the nitrogen atoms are turned into reaction products, and the main loss is gaseous N2. The process design has been performed by means of the Aspen PLUS process simulator, on the basis of literature data and other experimental results. In addition, for an evaluation of the potential benefits of the innovative biobased route, a life cycle analysis was carried out including all the stages involved in the bioacetonitrile production (from raw materials extraction up to the gate plant). The results were then compared with those achieved for the traditional fossil route (SOHIO process), showing a sensible decrease of the environmental burdens in terms of nonrenewable resources and damage to ecosystems (e.g., toxicity, climate change, etc.). Finally, a simplified sensitivity analysis was carried out by substituting the starting raw material for the production of bioethanol (corn) with other materials conventionally used worldwide, such as sugar cane and wood. The latter option seems to make the system more competitive in terms of carbon neutrality, thanks to the usage of the residual lignocellulosic fraction available on the market.
The bio-based substrate and target product 2,5-bishydroxymethylfuran (BHMF) demonstrated to influence the reaction kinetics in the homogeneous reduction of 5-hydroxymethylfurfural (HMF) catalyzed by ...the Ru-based Shvo's catalyst. A combined experimental and computational study supports an important role of the -CH2OH moiety which may be involved in the catalytic cycle toward the formation of different intermediates from HMF and BHMF. The reaction is selective and leads to quantitative formation of BHMF working under mild conditions. Furthermore, an optimized recycling procedure which avoids the use of water, allows recover and reuse of the catalyst without loss of activity. The mechanistic insights from this work may be extended to provide a general description of the chemistry of the Shvo's catalyst feeding further bio-based molecules.
The synthesis of terephthalic acid from biomass remains an unsolved challenge. In this study, we conducted the selective oxidation of p‐cymene (synthesized from biodegradable terpenes, limonene, or ...eucalyptol) into terephthalic acid over a Mn–Fe mixed‐oxide heterogeneous catalyst. The impact of various process parameters (oxidant, temperature, reaction time, catalyst amount, oxygen pressure) on the selectivity to terephthalic acid was evaluated, and some mechanistic aspects were elucidated. An unprecedented synthesis of biobased terephthalic acid (51 % yield) in the presence of O2 is reported.
Terrific terephthalic acid: A Mn–Fe mixed‐oxide heterogeneous catalyst is used for the selective oxidation of p‐cymene (synthesized from biodegradable terpenes, limonene, or eucalyptol) into terephthalic acid in a high yield of 51 % with O2 as the oxidant. The impacts of various process parameters on the selectivity to terephthalic acid are evaluated, and some mechanistic aspects are elucidated.
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