Platinum and palladium catalysts supported on two types of porous aromatic frameworks, PAF-30 and PAF-30NH2 (modified with amino groups), were examined in furfural hydrogenation. The influence of temperature, reaction time and solvent on selectivity and activity of the catalysts was investigated. Using isopropanol as solvent and conducting experiments at 40 degrees C led to sufficient decrease of side products yields. According to TEM Pt-PAF-30 and Pd-PAF-30-NH2 catalysts are characterized with uniform particles distribution on support. Elemental analysis shows a difference in palladium content between Pd-PAF-30 and Pd-PAF-30-NH2: 4.6% and 6.8% respectively. Whereas platinum catalysts have both 5.4% of metal. Catalyst Pt-PAF-30 was highly selective to tetrahydrofurfuryl alcohol (83 % yield), whereas the catalyst Pd-PAF-30-NH2 exhibited unusually high selectivity towards tetrahydrofurfural (77% yield). All studied catalysts were also tested in the hydrogenation of 5-hydroxymethylfurfural and 5-methylfurfural, in these experiments up to 20% yield of 1-hydroxy-4-hexen-2one was observed.

Noble metal catalysts based on porous aromatic frameworks modified with sulfo groups were studied in tandem alkylation-hydrogenation reaction between lignocellulose-derived furanic (furfural, furfuryl alcohol and 5hydroxymethylfurfural) and phenolic compounds (phenol, m-cresol, guaiacol) to produce high-density fuel precursors. Platinum catalysts were synthesized based on PAF-30-SO3H-3 and PAF-30-SO3H-5 supports with 3 and 5 % of sulfur, respectively, and both with 0.8 % of platinum. Hydroalkylation of mixtures of two substrates was performed. The reaction of guaiacol with furfuryl alcohol is characterized by the highest yields of long-chain products. The influence of substrates ratio, H2 pressure, reaction temperature and time on selectivity and activity of the catalysts was studied. The highest yield (77 %) of long-chain oxygenates among all experiments was achieved under the following reaction conditions: 2 MPa H2, 4 h, 130 degrees C and 1:8 mol/mol furfuryl alcoholguaiacol ratio. Catalysts Pd-PAF-30-SO3H-3 (with 1.1 % of palladium) and Ru-PAF-30-SO3H-3 (with 0.3 % of ruthenium) were tested in the tandem process to evaluate the impact of metal on reaction. To our knowledge, tandem alkylation-hydrogenation between biomass-derived furanics and phenolics over bifunctional catalysts based on organic polymers is reported for the first time. Moreover, some products of hydroalkylation (e.g., tricyclic oxygenates) haven't yet been described.

The paper describes an investigation into hydrogenation of furfural over ruthenium catalysts supported on porous aromatic frameworks. The supports were designated as PAF-30-SO3H, PAF-30-NH2, and PAF-30. The synthesized catalysts were tested in furfural hydrogenation carried out in water and in tetrahydrofuran (with a concentration of 10 wt

Heterogeneous catalysts play a crucial role in the petrochemical synthesis and oil refining industries [...]

In this work hydrodeoxygenation of various lignin-derived model compounds and their mixture was studied over platinum catalysts based on porous aromatic frameworks (PAF) doped with Bronsted acid sites. Two catalysts, Pt-PAF-30-SO3H(5.0) and Pt-PAF-30-SO3H(7.5), with almost identical platinum loading of 5.1 and 4.7 wt.

A porous aromatic framework, namely PAF-30, was structurally modified by the introduction of complexing groups based on dipyridylamine, dipicolylamine, and acetylacetone. The materials synthesized in this manner were used as supports of molybdenum catalysts for epoxidation: PAF-30-dpa-Mo, PAF-30-dpcl-Mo, and PAF-30-AA-Mo. All the materials were examined by various analytic methods, such as IR spectroscopy, low-temperature nitrogen adsorption/desorption, X-ray photoelectron spectroscopy, elemental analysis, and transmission electron microscopy. The catalytic activity was tested in epoxidation of cyclohexene, 1-hexene, 1-octene, and styrene. The reusability of the catalysts was assessed using the case of cyclohexene epoxidation.

Experiments on passivation of 1000–5000 ppm nickel on commercial zeolite-containing cracking catalysts were performed. The optimum passivator/nickel ratios for the catalysts containing up to 5000 ppm nickel were determined. The catalysts after the deactivation with nickel and its passivation were studied by such methods as temperature-programmed reduction with hydrogen, temperature-programmed ammonia desorption, X-ray diffraction analysis, and low-temperature nitrogen adsorption–desorption. The boron-containing passivator binds nickel into a difficultly reducible form, thus considerably reducing its dehydrogenating activity. The effect of deactivation of catalysts with nickel on their activity in the cracking of hydrotreated vacuum gasoil was demonstrated. The passivation of nickel in an amount of up to 5000 ppm with boron-containing compounds partially restores the activity of the commercial zeolite-containing catalyst in the cracking of hydrotreated vacuum gasoil.

Ruthenium catalysts supported on porous aromatic frameworks (PAFs) were synthesized using different protocols for metal impregnation to achieve high catalytic performance in the hydrogenation of levulinic acid. Significant effect of the support modification with functional groups (amino-, sulfo-) was demonstrated. The main factors affecting the process including substrate concentration, temperature, reaction time and hydrogen pressure were investigated. Ruthenium catalyst Ru-PAF-30-SO3H (COD) based on PAF-30 modified with sulfo groups synthesized with the use of 1,5-COD was able to promote levulinic acid dimerization at high temperatures (200-250 degrees C).

Here we report our investigation on auto-tandem reductive hydroformylation of ethylene, which allows to obtain propanol in a single technological step. The effect of pressure, ligand structure, temperature, solvent type, ratio of components, and gas supply on the process was studied. It was found that ethylene could be successfully converted to propanol by reductive hydroformylation on a homogeneous Rh/NR3 catalytic system with productivity per Rh atom up to 1299 h-1 (9.0 MPa, 110 celcius). Under milder conditions, low ethylene concentrations and constant syngas supply should be applied. Noteworthy, by using atmospheric distillation as a separation procedure, the system can be used for multiple consecutive reactions without significant activity loss. Probable pathways for the formation of active species and the transformation of rhodium complexes during the distillation process are discussed.

In this paper, we present a new simple approach to synthesizing catalysts for the oxidation of alkylaromatics based on the immobilization of metal ions by conventional ion exchange. By sulfation of high-stable porous polymers, porous aromatic framework (PAFs), we prepared the PAF-30-SO3H carrier, which was used for immobilization of Cu(II) and Fe(III) ions. The resulting Cu/PAF-30-SO3H and Fe/PAF-30-SO3H catalysts were successfully applied for the oxidation of ethylbenzene, 3-ethyltoluene, n-propylbenzene, Indane, and tetralin to the corresponding alpha-ketones. The catalysts were stable against metal leaching and showed high activity in alkylaromatics oxidation: The conversion of substrates reached 80% in 24 h at 80 degrees C, and did not decrease during for at least 5 cycles. The performance of catalysts was also compared with Cu/PAF-30-MEA and Fe/PAF-30-MEA catalysts, synthesized from PAF-30-MEA carrier, which structure was modified with monoethanolamine-based chelating groups. The structure of the materials and catalysts was established using advanced analytical techniques: low temperature N2 adsorption, elemental analysis, FTIR spectroscopy, solid state NMR, XPS, TEM, and EDX mapping.

Nanosized mixed tungsten-iron carbide (FeWC) was successfully applied in aerobic oxidative desulfurization. The combination of catalytically active centers responsible for the activation of oxygen and the oxidation of sulfur-containing compounds made it possible to obtain a highly efficient catalyst. The catalyst was synthesized by microwave irradiation, allowing to obtain a nanoscale catalyst in just 15 min. The catalyst was characterized in detail by a variety of methods: XRD, HRTEM, EDX, SEM, XPS, and low-temperature nitrogen adsorption/ desorption. The key factors influencing the dibenzothiophene (DBT) oxidation were investigated. Under opti-mized conditions DBT conversion was 100% in 1 h at 130 degrees C, 6 atm. The possible mechanisms including oxygen activation, alkyl peroxide formation, and substrate oxidation by tungsten peroxo-complexes were discussed. The catalyst retains its activity for at least 5 cycles of oxidation-regeneration. Aerobic oxidative desulfurization of straight-run gasoline in the presence of FeWC was performed and sulfur content was reduced from 995 to 6 ppm.

The review analyzes recent publications dealing with the search for new efficient desulfurization technologies, in particular, oxidative desulfurization using ionic liquids. This technology attracts attention due to its relatively mild conditions compared to hydrodesulfurization and its efficiency in removing heavy sulfur derivatives. Of special interest are solid hybrid compositions consisting of a support coated with an ionic liquid layer containing catalytically active centers. Examples of the use of such polyfunctional systems, simultaneously functioning as an adsorbent, extractant, and catalyst, for the oxidative desulfurization of model fuel and real oil feedstock are considered.

A ruthenium catalyst based on hexagonal mesoporous silica modified with aluminum (Al-HMS structural type) of a Si/Al ratio equal to 10 was studied in the hydrodeoxygenation reaction of bio-oil components containing a guaiacol fragment. The catalyst was tested in the hydrodeoxygenation of guaiacol, methoxyguaiacol, formylguaiacol, and propylguaiacol in the presence of water at a hydrogen pressure of 6.0 MPa and a temperature of 250°C. The effect of the substrate structure on the conversion and selectivity of hydrotransformation towards fully hydrogenated and deoxygenated products is shown. The effect of temperature in the range of 210–290°C on the conversion and distribution of guaiacol hydrodeoxygenation products at various hydrogen pressures (2.5 and 6.0 MPa) is demonstrated. Experiments were carried out on the hydrodeoxygenation of guaiacol in a mixture with water, n -dodecane, and methanol at a hydrogen pressure of 6.0 MPa and a temperature of 250°C. The effect of the model mixture composition on the conversion and distribution of guaiacol hydrodeoxygenation products is shown.

A new phosphorous-free rhodium supported on a nitrogen-doped silica was successfully used as a catalyst for the hydroformylation of alkenes. The obtained material and the catalyst were characterized by XRD, XPS, FTIR, SEM, TEM, ICP AES, and low-temperature nitrogen adsorption–desorption measurements. The catalytic performance was studied by the example of the hydroformylation of octene-1 at temperatures of 80–140 °C and a pressure of 5.0 MPa. The catalyst provided a 99% conversion of 1-octene with a 98% yield of aldehydes and showed a good conversion of styrene and cyclohexene. The catalyst can be repeatedly used in ten consecutive cycles, with its activity remaining constant.

The study investigated hydrogenation of aromatics as liquid organic hydrogen carriers over unsupported NiMoS catalysts synthesized in situ by dispersion followed by high-temperature decomposition/sulfidation of oil-soluble precursors of the active component in a hydrocarbon medium. The separation of hydrogen from gas mixtures via its chemical storage was demonstrated. The hydrogenation of naphthalene, its monomethylated derivatives, and anthracene was investigated with various component ratios in the gas mixtures. Specifically, the effects of temperature, pressure, reaction time, and the presence of water under water gas shift reaction (WGSR) conditions on the substrate conversion and product selectivity were evaluated. When carrying out the process in syngas atmosphere (CO : H2 = 1 : 1) at 340°C and 5 MPa, the aromatics conversion and the hydrogen saturation were found to decrease in the following order: anthracene > 2-methylnaphthalene ≈ naphthalene >> 1-methylnaphthalene. In addition to steric hindrances in the sorption of substrate molecules (due to the presence of substituents in the benzene ring), the structure of conformational isomers of intermediate molecules has a major effect on the hydrogenation reaction rate. Dispersed NiMoS catalysts were found to be active in the hydrogenation of 2-methylnaphthalene, achieving at least 90

Bifunctional catalysts are a major type of heterogeneous catalytic systems that have been widely investigated for biomass upgrading. In this work, Ru-catalysts based on sulfonated porous aromatic frameworks (PAFs) were used in the hydrodeoxygenation (HDO) of lignin-derived compounds: guaiacol, veratrole, and catechol. The relationship between the activity of metal nanoparticles and the content of acid sites in synthesized catalysts was studied. Herein, their synergy was demonstrated in the Ru-PAF-30-SO3H/5-COD catalyst. The results revealed that this catalytic system promoted partial hydrogenation of lignin-based compounds to ketones without any further transformations. The design of the Ru-PAF-30-SO3H/5-COD catalytic system opens a promising route to the selective conversion of lignin model compounds to cyclohexanone.

Three rhodium-containing catalytic systems active in tandem hydroformylation/hydrogenation of unsaturated substrates were developed based on polyethyleneimine (PEI): a homogeneous system with distillation of the product; a biphasic system with segregation of the product and catalyst into a non-polar phase and a polar phase, respectively; and a solid catalyst prepared from PEI and (3-chloropropyl)triethoxysilane with its centrifugation from the product mixture. All the systems were shown to be reusable over multiple cycles in hydroformylation/hydrogenation, with the catalytic activity being partially sustained in both steps of the tandem process. Methylation of PEI (or its NH and NH 2 moieties in the case of solid material) was found to be critical for the catalytic activity in hydroformylation.

The paper describes synthesis of ruthenium and nickel catalysts supported on aluminum-modified SBA-15 (Santa Barbara Amorphous-15) mesoporous silicate, designated as Al-SBA-15, with a Si/Al ratio of 20. The catalysts were investigated in aqueous-phase hydrogenation of furfural, a valuable product obtained from lignocellulosic biomass. Elevating the reaction temperature from 200 to 250°C and the hydrogen pressure from 3 to 5 MPa enhanced the selectivity towards methyltetrahydrofuran (MTHF). The ruthenium catalyst outperformed its nickel counterpart in terms of activity in aqueous-phase furfural hydrogenation (250°C, 5 MPa H 2 ).

Heterogeneous catalysts with Bronsted acid sites based on the porous aromatic framework (PAF) were applied for the oxidative denitrogenation process. Sulfonic groups immobilized on the PAF-20 support can form active peracid in the presence of hydrogen peroxide and on the other hand can efficiently coordinate both nitrogen- and sulfur-containing compounds, which are Lewis bases. This approach allows us to obtain efficient catalysts for oxidation of various types of nitrogen-containing compounds as well as sulfur-containing compounds and their mixtures. The main factors affecting the process consisting of the sulfonic group content, catalyst dosage, temperature, hydrogen peroxide amount, as well as concentration were investigated in detail. In the presence of the most active catalyst PAF-SO3H 500 under optimal reaction conditions, relatively inert carbazole was removed by 95% in just 10 min. Sulfonic groups are strong bonded to support which allows us to prevent their leaching and retain catalyst activity up to five cycles of oxidation regeneration.

The present review compiles the advances in the dendritic catalysis within the last two decades, in particular concerning heterogeneous dendrimer-based catalysts and their and application in various processes, such as hydrogenation, oxidation, cross-coupling reactions, etc. There are considered three main approaches to the synthesis of immobilized heterogeneous dendrimer-based catalysts: (1) impregnation/adsorption on silica or carbon carriers; (2) dendrimer covalent grafting to various supports (silica, polystyrene, carbon nanotubes, porous aromatic frameworks, etc.), which may be performed in a divergent (as a gradual dendron growth on the support) or convergent way (as a grafting of whole dendrimer to the support); and (3) dendrimer cross-linking, using transition metal ions (resulting in coordination polymer networks) or bifunctional organic linkers, whose size, polarity, and rigidity define the properties of the resulted material. Additionally, magnetically separable dendritic catalysts, which can be synthesized using the three above-mentioned approaches, are also considered. Dendritic catalysts, synthesized in such ways, can be stored as powders and be easily separated from the reaction medium by filtration/centrifugation as traditional heterogeneous catalysts, maintaining efficiency as for homogeneous dendritic catalysts.