Katarína Fabičovicová

Hydrogenolysis of cellulose to valuable chemicals over activated carbon supported mono- and bimetallic nickel/tungsten catalysts

The hydrogenolysis of cellulose was systematically investigated at 488 K and under 65 bar H2 in the absence of a catalyst and over six different catalytic systems containing nickel and/or tungsten on activated carbon (AC) in order to understand the role of individual active components (AC, W/AC, Ni/AC, a physical mixture of Ni/AC + W/AC, and two differently prepared Ni/W/AC catalysts) with respect to the product distribution wherein polyols (e.g. ethylene glycol (EG), propylene glycol, and sorbitol) are highly valuable chemicals. Without a catalyst and when using only AC, a hydrochar, due to hydrothermal carbonization of cellulose, was obtained. Although the catalyst W/AC was effective for the degradation of cellulose (high conversion of 90%) and facilitates C–C bond cleavage, selective production of any product was not possible, and the carbon efficiency (CEL) is the lowest (9.1%). Also, with highly dispersed Ni on AC the polyol yield was only 5.3%. The desired behavior showed Ni/W/AC provided its preparation occurs by a two-step incipient wetness (IW) technique. Starting with a remarkably high cellulose/catalyst ratio of 10, a cellulose conversion of 88.4%, CEL of 78.4% and EG yield of 43.7% were achieved (overall polyol yield = 62.1%). Drastically lower yields towards EG by an order of magnitude and decreased CEL were obtained by a co-impregnated Ni/W/AC catalyst and the Ni/AC + W/AC mixture. By the detailed analysis via XRD, TPR and CO chemisorption, it can be concluded that in the Ni/W/AC catalyst, after the first IW step of the activated carbon with ammonium metatungstate hydrate and the following reduction in H2 up to 1128 K, metallic tungsten was formed. This leads, in combination with the hydrogenation properties of nickel introduced in the second IW step, to a virgin bimetallic catalyst, i.e. before the hydrogenolysis starts, in which both components must be metallic. This is a prerequisite for high polyol production. Finally, varying the AC type, high space–time-yields up to 2.5 g polyols (gcatalyst h)−1 were obtained. A slight deactivation after two runs followed by a strong decrease of polyol yield in the next two runs was observed. Leaching and structural changes on the catalyst surface (formation of NiWO4) are mainly responsible for deactivation.

From microcrystalline cellulose to hard- and softwood-based feedstocks: their hydrogenolysis to polyols over a highly efficient ruthenium–tungsten catalyst

The utilization of cellulose and its integration in a biorefinery concept is essential even in the near future due to the growing global shortage of crude oil. Here, we report the catalyzed one-pot hydrogenolysis of cellulosic materials to valuable bio-derived molecules, especially polyols (e.g. ethylene glycol). We demonstrate how a very promising bifunctional catalyst, Ru/W/AC, converted not only 100% of microcrystalline cellulose to polyols in repeated experiments with a maximum yield of 84% and an ethylene glycol productivity of 3.7 g (gcatalyst h)−1, but also pine-, birch-, and eucalyptus-derived materials. Moreover, we systematically investigated the problem of catalyst stability with time by studying the changes in both the catalyst structure and the liquid phase, which have often been overlooked when biomass is converted to fuels and chemicals. Control of the active sites for the conversion of cellulosic feedstocks coupled with reaction engineering and strategies to prevent catalyst deactivation, is a prerequisite to understanding how high yields of platform chemicals can be achieved.

From Barley Straw to Valuable Polyols: A Sustainable Process Using Ethanol/Water Mixtures and Hydrogenolysis over Ruthenium‐Tungsten Catalyst

Organosolv fractionation of barley straw followed by a hydrogenolysis reaction of the resulting organosolv pulp over a heterogeneous catalyst containing ruthenium and tungsten on activated carbon (Ru-W/AC) is a potential pathway to produce valuable chemicals from lignocellulose-based feedstock in a future biorefinery. Polyols, such as ethylene glycol, propylene glycol, or 1,2-butanediol, can be obtained with a very high yield of 70u2009% using organosolv barley pulp pretreated in a 50:50u2005wtu2009% ethanol/water solution at 200u2009°C and a processing time of one hour. Moreover, we investigated the influence of several pretreatment parameters (e.g., solvent/water ratio, reaction temperature, and reaction time) on the pulp composition and product distribution obtained during the hydrogenolysis reaction to reduce the production of undesired side molecules. Finally, the optimal organosolv pretreatment conditions for straw were successfully transferred to other lignocellulose-based feedstock, namely bamboo foliage and hemp shives.

Hydrothermally Stable Ruthenium–Zirconium–Tungsten Catalyst for Cellulose Hydrogenolysis to Polyols

In this work, we describe a catalytic material based on a zirconium–tungsten oxide with ruthenium for the hydrogenolysis of microcrystalline cellulose under hydrothermal conditions. With these catalysts, polyols can be produced with high yields. High and stable polyol yields were also achieved in recycling tests. A catalyst with 4.5u2005wtu2009% ruthenium in total achieved a carbon efficiency of almost 100u2009%. The prepared Zr‐W oxide is mesoporous and largely stable under hydrothermal conditions (493u2005K and 65u2005bar hydrogen). Decomposition into the components ZrO2 and WO3 could be observed at temperatures of 1050u2005K in air.

Conversion of cellulose and lingo-cellulosic based feedstock over heterogeneous catalysts into liquid polyols

C Nanocrystals (NCs) are solution-grown, nanometer-sized, inorganic particles that are stabilized by a Self-Assembled Monolayer (SAM) of surfactants attached to their surface. NCs possess useful properties that are controlled by their composition, size and shape, and the SAM coating ensures that these structures are easy to fabricate and process further into more complex structures. This combination of features makes colloidal NCs attractive and promising building blocks for advanced materials, green chemistry, and specifically in catalysis. Colloidal NCs are potentially able to blend the many advantages of heterogeneous catalysis with the versatility of homogeneous catalysts. This presentation will focus on: (i) Advantages of continuous-flow processing in in-situ preparation of Fe3O4 NCs from a Fe (e.g., FeCl2·4H2O, FeCl3·6H2O, and Fe(OAc)2) precursor using hydrazine hydrate as the reducing agent to catalyze the organic reactions (e.g., reduction of nitroarenes) and (ii) Shape-selective synthesis of TiO2 colloidal NCs and their application in a continuous-flow photocatalytic transformation.P have evolved bioactive metabolites of great complexity and potency, however the compounds found in the wild-type plant representonly a fraction of the genomic capability of the species, If we could only “tell” plants what bioactivity we required from them, this would open a new chapter in plant drug discovery. Naprogenix’ novel technology achieves this by “evolving” plant biosynthesis, via mutation and selection, toward metabolites targeted on specific proteins. This can increase yields of known compounds, or generate active metabolites which are not detectable in the wild-type plant. Proof of concept has used several plant species and several targets, but this example describes the production of inhibitors of the human dopamine transporter (DATa molecular target in Parkinson’s disease) in cell cultures of a native Lobelia species. This plant contains small amounts of lobinaline, a previously uninvestigated inhibitor of the DAT, which would be a conventional lead compound except that it is a complex binitrogenous alkaloid with 5 chiral centers and no known chemical synthesis. However, this complexity makes it an excellent example of the value of target-directed biosynthesis. First, we expressed the human DAT target protein in cells of this species, making them susceptible to a cytotoxin which is accumulated intra cellularly by the DAT. Mutants which are overproducing inhibitors of the DAT now have a survival advantage when exposed to the toxin. About 1/300 gain-of-function mutants survived selection, providing 120 toxin-resistant individual clones. Extracts from 41 of these showed greatly increased levels of DAT inhibition, and 16 of these were overproducing lobinaline. However, the other 25 clones were overproducing other metabolites, 8 of which were not detectable in the wild-type plant. Several of these showed chemical similarity to lobinaline and putatively represent a biosynthetic active compound library. In this way it is possible to tell a plant species to synthesize metabolites with a specific bioactivity and, by selection, the plant cell also does the initial pharmacological screening. Mankind can become the orchestrator of plant biosynthetic evolution rather than its passive beneficiary.T chemical fixation and activation of CO2 by metal complexes may lead to certain devices that can eliminate the CO2 present in the air and hence controlling its concentration and reducing the environmental problems due to the greenhouse effect and global warming. This can be achieved by designing “inexpensive inorganic compounds” that rapidly and effectively catalyze the atmospheric CO2 fixation. In slightly basic solutions, the atmospheric fixation of CO2 by metal complexes, through hydroxo-species, afford the carbonato metal complexes. A number of simple N-donor ligands and multi-dentate Schiff bases containing two or three N-atoms, phenolic and alkoxy groups are to used synthesize a series of 3d(M(II) = Ni, Cu, Zn) and 4f(Ln(III) = lanthanides) complexes. The incorporation of lanthanide (III) ion into the skeleton of3d complexes to produce 3d-4f heteronuclear metal complexes should increase the affinity of the compounds for CO2 fixation into the Ln (III) pocket (Ln3+ ion is a hard Lewis acid which strongly bound to hard Lewis bases; O-donor species such as CO32ion). The carbonato complexes are not only interesting from the structural and geometrical points of view, but alsomay result in the discovery of interesting Single Molecular Magnets (SMM’s) which can be used to increase the memory of the computers. The resulting carbonato-bridged compounds can also be used to prepare some useful organic compounds. Recent developments concerning synthesis and structure characterization of different coordination carbonato-bridged compounds, magnetic properties and their potential applications will be addressed.T global drive towards the reduction of energy consumption, emissions and minimisation of waste are increasingly important and becoming major technological, political and societal issues. A promising approach to address the current challenges is to adopt green chemistry and sustainability during process design, innovation, integration and optimisation. The use of green chemistry and process intensificationin the processing of polymeric, inorganic and composite materials will be described. The emerging of eco-friendly and sustainable non vacuum chemical processing technologies will be presented for the production of nanostructured materials and high value added superthin/thin films and thick coatings. These processes that are not only low cost, less polluting, conserve energy, reduce waste but also increase efficiency and enhance product performance. Case studies leading to sustainable products and increasing profits for a variety of applications, including fine chemicals, clean energy, engineering, and biomedical sectors will be presented.S succinate, a pharmaceutical used in industry is an organic contaminant that has the potential to create environmental toxicity and pollution problems and cause health risks for humans as well as biota. Natural organic matters, such as humic acid, HA in aquatic environments can increase the stability of nanoparticles. In this work, solifenacin succinate in wastewater was removed by a biosorption method using HA-coated TiO2 nanoparticles. The FTIR, EDX and FESEM studies were used to characterize the fabricated nanosorbents. Mathematical adsorption and kinetics models representing the biosorption processes were formulated, supporting the Langmuir isotherm and pseudo-second order rate equation for the adsorption of aqueous solifenacin succinate using batch mode experiments. All parameters influencing the removal efficiency such as: Adsorbent dose, medium pH, initial adsorbate concentration and temperature were considered for optimizing the experimental conditions. Thermodynamic study was carried out to describe the feasibility, thermic and entropic behaviors of the investigated biosorption process. The results showed that the method developed here is very effective for the removal of solifenacin succinate from an aqueous environment.C is one of the most powerful tools of green chemistry, enabling reactions with lower energy consumption and providing new pathways for bond formation. Catalytic C-H functionalizations, in particular, are powerful methodologies for installing functional groups in previously non-functionalized positions of a molecule and the use of catalyst directing groups has enabled a wide variety of exciting bond formations with remarkable selectivities and broad applicability. One of the greatest current challenges in this research area is how to catalyze analogous C-H functionalization reactivity without the presence of catalyst directing groups. Such transformations often suffer from the lack of a strong catalyst pre-coordination, which can lead to lower reactivities. The research described in this presentation will showcase basic principles of catalyst and methodology design to achieve non-directed C-H functionalizations and provide insights into reactivity and selectivity-determining factors for the C-H aminations of arenes and the alpha-C H oxidation of tertiary amines.P synthesis has received significant recent research interest in the context of ideal synthesis and green sustainable chemistry. In general, organolithium species react with electrophilic functional groups very rapidly, and therefore such functional groups should be protected before an organolithium reaction, if they are not involved in the desired transformation. If organolithium chemistry could be free from such a limitation, its power would be greatly enhanced. A flow microreactor enables such protecting-group-free organolithium reactions by choosing the appropriate residence time and the reaction temperature. Organolithium species bearing alkoxycarbonyl, nitro, and ketone carbonyl groups can be generated and reacted with various electrophiles using a flow-microreactor system. In addition, asymmetric carbolithiation of conjugate enzymes can be also achieved without the epimerization of a configurationally unstable chiral organolithium intermediate based on precise control of the residence time using a flow microreactor. In this presentation, we report that a flow microreactor system enables the generation of various unstable organolithium compounds.D green catalysts is the key for the development of next-generation technologies to convert biomass molecules into liquid fuels or other value-added chemicals. Recently, a few hydrogenation catalysts have been developed to effectively drive biomass conversions. However, designing hydrogenation catalysts that can work under mild conditions such as low pressure, low temperature, and green solvent remains a challenge. To provide the insights for designing greener hydrogenation catalysts, we explored the thermodynamics conditions (e.g., temperature, pressure, and solvents) for various hydrogenation or hydrogenolysis reaction based on biomass model compounds, by combining the Ab initio quantum chemistry calculations and experimental explorations. Our results show that thermodynamically it is indeed possible to design greener catalysts (e.g., robust and economic catalysts that work under mild conditions) for converting biomass molecules into value-added chemicals. In addition, we showed that optimal hydrogenation catalysts could be sought under the guidance of inverse design methods.We report densities, ijk ρ and speeds of sound, ijk u of 1-ethyl-3-methylimidazolium tetrafluoroborate (i) + water (j) + formamide or N,N- dimethylformamide (k) ternary mixtures over entire composition range at 293.15, 298.15, 303.15, 308.15 K. The heat capacities, Cpof 1-ethyl-3-methylimidazolium tetrafluoroborate, water, formamideand N,N- dimethylformamide have also been measured at 293.15, 298.15, 303.15, 308.15 K using micro differential scanning calorimeter (Model -µDSC 7 Evo). The measured ijk ρ and ijk u data have been utilized to determine their excess molar volumes, E ijk V andThe presence of bark in wood can constitute a serious limitation for the bioconversion of forest residues into bioethanol, especially due to the presence of high content of extractives, which may inhibit ethanol fermentation. However, a perfectly debarked wood chip may not represent an economical source of carbohydrates for industrial applications. An option is to utilise bark as a source of renewable energy and chemicals, within a biorefinery platform. In this study, enzymatic hydrolysis and bioethanol fermentation of Douglas-fir bark were studied before and after organosolv and diluted acid pre-treatments performed at 150°C and 180°C. The recovery of valuable platforms molecules was also determined after pre-treatment. Results showed that an organosolv-free acid pre-treatment performed at 150°C gave the best results in terms of platforms molecules recovery (40% w/w) and bioethanol yield (2 g.100g-1 total solids). However, the low glucose and ethanol yields obtained (6% and 16% of the theoretical values, respectively) confirmed that enzymatic hydrolysis remains the limiting step of bioethanol fermentation from bark. Interestingly, ethanol was produced without inhibition of fermentation from the untreated and pretreated substrates.W have studied in the last 15 years the efficiency of oxime-derived palladacycles as pre-catalysts in carbon-carbon forming reactions such as, Heck, Suzuki, Stille, Hiyama, Ullmann, Sonogashira and Glaser reactions by in situ generation of palladium nanoparticles. Interestingly, they exhibit increasing catalytic activity when water is used as solvent due to the formation of threeand four-palladium atom clusters as has been recently found out by Corma and col. In this talk recent challenge applications of these palladacycles working in aqueous media will be presented. Matsuda-Heck reactions have been performed efficiently in water at rt. In the case of the Suzuki-Miyaura reaction, deactivated aryl chlorides and imidazolylsulfonates can be cross-coupled with boronic acids or potassium trifluoroborates using water as solvent. The copper-free Sonogashira reaction has been also performed with deactivated aryl chlorides and with aryl imidazolylsulfonates under copper-free conditions using water as solvent. The head to head dimerization of terminal alkynes in water allows the steroselective preparation of (E)-1, 4-enynes in the presence of an imidazolinium salt.