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Research of the catalysts activity in the reactions of model compounds and their mutual influence was carried out. Quinoline is able to promote the hydrodesulfurization reaction of dibenzothiophene (DBT), being a source of hydrogen in the system at 260 °C. The possibility of intermolecular hydrogen transfer reactions in the reactions of tetrahydroquinoline and DBT is shown. [ABSTRACT FROM AUTHOR]

Pt/Sup catalysts with SiO2, MCM-48, and Al2O3 supports (Sup) were prepared. The catalysts were studied by methods of low-temperature nitrogen adsorption, temperature-programmed reduction, and high-resolution transmission electron microscopy. The kinetic characteristics of hydrogenation of biphenyl and diphenylmethane taken separately and of their eutectic mixture were studied on a flow-through catalytic installation at temperatures of 150–170°С, pressure of 4 MPa, liquid hourly space velocity (LHSV) of 5–15 h–1, and hydrogen/feed ratio of 500 m3n.c./m3. A biphenyl–diphenylmethane eutectic mixture (weight ratio 35 : 65) was used as a model mixture. According to the data obtained, the catalyst activity decreases in the order Pt/MCM-48 > Pt/Al2O3 > Pt/SiO2. The use of mesostructured silicate MCM-48 as a support allows the dispersity of the active phase to be increased compared to the traditional SiO2 and Al2O3, which enhances the catalyst activity in hydrogenation of biphenyl and diphenylmethane. [ABSTRACT FROM AUTHOR]

Vapor pressures for the main component of the biodiesel – methyl oleate were measured by using the static method. For this purpose, a new setup for vapor pressure measurements in the range (0.1 to 1000) Pa and the elevated temperatures up to 450 K has been designed and tested using the reference materials benzoic acid and naphthalene. Absolute vapor pressures and sublimation (vaporization) enthalpies for the tested compounds were in a good agreement with the most reliable literature data. [ABSTRACT FROM AUTHOR]

The absolute vapor pressures over the solid and liquid 2-biphenylmethanol and 4-biphenylmethanol were measured using the transpiration method. The standard molar enthalpies of vaporization/sublimation were derived from the temperature dependence of vapor pressures. The standard molar enthalpy of fusion of 2-biphenylmethanol was measured using DSC. The available data on solid-gas, liquid-gas and solid-liquid phase transitions available in the literature have been collected, combined with own experimental results and evaluated using the structure-property relationships and quantum-chemical calculations. The high-level G3MP2 and G4 quantum-chemical methods were used to establish consistency of the experimental and theoretical results. Conformational analysis of 2-biphenylmethanol showed the possible presence of a hydrogen bond between the hydroxyl group and the aromatic ring. The strength of the intramolecular hydrogen bonding in 2-biphenylmethanol and 4-biphenylmethanol was assessed from thermochemistry and quantum-chemical calculations. [ABSTRACT FROM AUTHOR]

Extraction of undesirable components from light catalytic cracking gasoil with N-methylpyrrolidone was studied. Extraction conditions were chosen, and the influence of the solvent to feed ratio on the process results was determined. Low solvent to feed ratios are favorable for obtaining highly concentrated extracts for the subsequent production of a liquid organic hydrogen carrier from them. The solvent to feed ratio of 0.75 : 1.00 can be recommended for obtaining a high-density jet fuel component. [ABSTRACT FROM AUTHOR]

New experimental vapor pressures in the range 375–412 K and vaporization enthalpy of the ionic liquid (IL) 1-ethyl-3-methylimidazolium diethyl phosphate have been measured by the Quartz Crystal Microbalance. Results are useful for chemical engineering calculations of processes involving ILs. [ABSTRACT FROM AUTHOR]

Ibuprofen is a well-established non-steroidal anti-inflammatory drug, inhibiting the prostaglandin-endoperoxide synthase. One of the key features defining the ibuprofen structure is the doubly intermolecular O–H⋯O＝C hydrogen bond in cyclic dimers as know from carboxylic acids and confirmed by X-ray analysis. Until now, there was neither information about the vaporization enthalpy of ibuprofen nor about how this thermal property is determined by the subtle balance between different types of intermolecular interaction. In this study we derive the vaporization enthalpy of ibuprofen from thermochemical experiments to be. We dissected the hydrogen bond energy, EHB = 45.0 kJ mol−1, exclusively from measured vaporization enthalpies of related aliphatic carboxylic acids, their homomorph methyl esters and alkyl acetates, respectively. This contribution from hydrogen bonding could be confirmed almost quantitatively from quantum chemical calculations of ibuprofen clusters, which also suggest dispersion interaction of similar order (Edisp = 47 kJ mol−1). Following the full analysis of the gas–vapor transition enthalpy, we studied the changing structural components from the solid to the liquid phase of ibuprofen by means of Attenuated Total Reflection Infrared (ATR-IR) spectroscopy. The cyclic dimers as observed in the X-ray patterns are essentially preserved in the liquid state just above the melting point. However, with increasing temperature the doubly hydrogen-bonded cyclic dimers are replaced by singly hydrogen-bonded linear dimers in the liquid ibuprofen. The transfer enthalpy from the temperature-dependent equilibria of both dimers as obtained from the IR intensity ratios of the vibrational bands quantifies for the first time the energy of the released, single hydrogen bond to be EHB = 21.0 kJ mol−1. Overall, we show that a combination of thermodynamics, infrared spectroscopy and quantum chemistry provides quantification and detailed understanding of structure and molecular interaction in ibuprofen and related compounds. [ABSTRACT FROM AUTHOR]

Pt catalysts supported on the commonly used supports Al2O3, SiO2 and on mesostructured silicates SBA-15 and MCM-48 were examined in the dehydrogenation of decalin, that is the promising liquid organic hydrogen carrier (LOHC). Synthesized catalysts were studied by low-temperature nitrogen adsorption, temperature programmed reduction, high-resolution transmission electron microscopy. The catalysts are characterized by various dispersion of platinum. The activity of catalysts in decalin dehydrogenation decreases in the following order Pt/MCM-48 > Pt/SBA-15 > Pt/SiO2 > Pt/Al2O3. Pt/MCM-48 catalyst allows to release hydrogen in the decalin amount of 5.7 wt% and can be considered the promising LOHC hydrogen storage technology. [ABSTRACT FROM AUTHOR]

NiMoW/P-Al2O3 catalysts were synthesized with a different ratio of Mo:W (W-free sample, Mo:W = 2:1, Mo:W = 1:1, Mo:W = 1:2 and Mo-free sample) and various P2O5 contents in the carrier (up to 5 wt%). The surface of the sulfide phase of the samples was investigated by means of high-resolution transmission electron microscopy (HR TEM) and X-ray photoelectron spectroscopy (XPS). The catalytic activity of patterns was estimated in the reactions of hydrodesulfurization of dibenzothiophene (DBT) and hydrogenation of naphthalene. The results are presented in the form of three-dimensional diagrams "P2O5 content—ratio Mo/W—catalytic activity" or "P2O5 content—ratio Mo/W—property". The influence of the phosphorus content on the maximum peak position of the binding energy S2p/1 of the S2− atomic group for the investigated systems is shown. Comparison of the shape of the curve of changes in the binding energy with the previously presented results on the catalytic activity of the samples in the HDS of a vacuum gas oil allows us to conclude that phosphorus is able to change the electronic state of the active phase of the catalysts, which leads to a change in their catalytic activity in the reactions of HDS. [ABSTRACT FROM AUTHOR]

The five fundamental units of the genetic code: uracil (U), thymine (T), cytosine (C), adenine (A) and guanine (G) are known for extremely low vapor pressure and low thermal stability at elevated temperatures. Therefore, application of conventional techniques for the determination of sublimation enthalpies and vapor pressures fails to provide accurate results. Recently, a Fast Scanning Calorimetry method (FSC) for vapor pressure determination was developed for investigation of extremely low volatile, as well as for thermally unstable molecular and ionic molecules. This success has encouraged application of the FSC method for determination of vapor pressures and sublimation enthalpies of the five nucleobases, where available literature data are in disarray. The thermodynamic data of the nucleobases available in the literature were collected, evaluated, and combined with our experimental results to reconcile available experimental data. The set of evaluated thermochemical data on the five nucleobases was recommended as the benchmark properties for these thermally labile compounds. [ABSTRACT FROM AUTHOR]

Supported CoMoS and NiWS catalysts were synthesized on the basis of an Al2O3—SAPO-11 composite support. The acid and texture characteristics of the thus synthesized materials were examined. The morphologies of the active sulfide phase of the catalysts were compared. The kinetic properties of the supported sulfide catalysts in the reaction of hydroisomerization of n-hexadecane and in the hydroprocessing of the diesel fraction were examined. It was shown that it is possible to obtain hydrogenates with improved low-temperature properties in the presence of supported sulfide catalysts containing no noble metals. [ABSTRACT FROM AUTHOR]

Walden's Rule is an empirical observation of an invariant fusion entropy during fusion of non-associated organic compounds. For the five nucleobases, adenine, thymine, cytosine, guanine, and uracil, surprisingly high fusion temperatures and enthalpies have been measured using a specially developed fast scanning calorimetry method that prevents decomposition. Even when nucleobases admittedly possess very high fusion temperatures, e.g. the value of 862 K measured for guanine really exceeds all expectations of the feasible dimension of the fusion temperature for such a relatively small and simple organic molecule. Hirshfeld surface analysis has been applied in order to find out an explanation for such extremely unusual thermal behavior of nucleobases. We rationalized the observed trends in terms of fusion entropy (Walden's constant = 56.5 J K−1 mol−1) as the entropic penalty of fusion not only for “non-associated”, as proposed by Walden in 1908, but also for “ideal associated” systems like nucleobases. [ABSTRACT FROM AUTHOR]

MoS2/Al2O3 and NiMoS2/Al2O3 catalysts were prepared by incipient wetness impregnation of alumina using aqueous solutions of 12-molybdophosphoric heteropolyacid and nickel citrate. Unsupported catalysts were prepared by etching a support made from MoS2/Al2O3 using hydrofluoric acid (Et-MoS2) and thermal decomposition of aluminum tetrathiomolybdate (Ref-MoS2). The activity of the catalysts in hydrodeoxygenation decreases in the series NiMoS2/Al2O3 = Et-MoS2 > MoS2/Al2O3 > Ref-NiS2. On the other hand, the selectivity relative hydrogenation of oleic acid has a different order: Et-MoS2 > MoS2/Al2O3 > Ref-MoS2 > NiMoS2/Al2O3. The unsupported Et-MoS2 catalyst has similar activity to NiMoS2/Al2O3 in hydrodeoxygenation and the highest selectivity, which indicates virtually completion of the hydrodeoxygenation reaction through a hydrogenation pathway without the formation of CO or CO2. These gases display strong inhibiting properties and have a detrimental eject on the environment. [ABSTRACT FROM AUTHOR]

Ni/Sup catalysts were prepared, where SBA-15, γ-Al2O3, SiO2 were used as supports (Sup). The synthesized catalysts were investigated by the methods of low-temperature nitrogen adsorption, temperatureprogrammed reduction (TPR), and high-resolution transmission electron microscopy. The catalytic properties of the prepared catalysts were tested in liquid phase hydrogenation of biphenyl under conditions of a flow installation at temperatures of 60-100°C, pressure of 4 MPa, volumetric feed rate of 4-10 h-1 and H2: feed ratio of 1500 nM.. A 1 wt % solution of biphenyl in heptane, as a model mixture, was used. It has been established that the activity of nickel hydrogenation catalysts depends on the nickel content and the type of support. The activity of supported nickel catalysts decreases in the series Ni-12/SBA-15 > Ni-12/SiO2 >> Ni-12/Al2O3. The kinetic characteristics of the biphenyl hydrogenation reaction were determined: the rate constants and activation energy for the hydrogenation of the first and second aromatic rings of the substrate molecule. [ABSTRACT FROM AUTHOR]

A series of catalysts have been synthesized Ni-Mo-W/P-Al2O3 with different Mo: W ratios (a sample without W, Mo: W = 2: 1, Mo: W = 1: 1, Mo: W = 1: 2, and a sample without Мо) and a concentration of P2O5 in a support of 0.5 wt %. Heteropoly acids H3PMo12O40 · nH2O and H3PW12O40 · nH2O and nickel citrate were precursors of the active phase. High-resolution transmission electron microscopy and X-ray photoelectron spectroscopy were used to study the surface of the sulfide phase of the samples. Their catalytic activity was estimated in the reactions of dibenzothiophene hydrodesulfurization and naphthalene hydrogenation. A catalyst with the ratio Mo: W = 1: 1 showed the highest activity, and was characterized by the maximum concentration of atomic groups Ni-Mo-W-S, Mo-S, and W-S. [ABSTRACT FROM AUTHOR]

A series of NiMoW/P-Al2O3 catalysts with different Mo/W ratios (sample containing Mo only, Mo/W = 2: 1, Mo/W = 1: 1, Mo/W = 1: 2, and sample containing W only; P2O5 content of the support 2.0 wt %) were synthesized. The precursors of the active phase were the heteropoly acids H3PMo12O40∙nH2O and H3PW12O40∙nH2O, and also nickel citrate. The sulfide phase in the samples was studied by high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy; the catalytic activity of the samples in dibenzothiophene hydrodesulfurization and naphthalene hydrogenation was determined. For the dibenzothiophene hydrogenolysis in the presence of quinoline and naphthalene (content in the model mixture, wt %: dibenzothiophene 0.3, naphthalene 1.5, and quinoline 0.5), kHDS for different samples is in the range 17.6-42.5 h-1 at 275°C and 24.6-45.9 h-1 at 300°C. For the naphthalene hydrogenation, kHYD varies from 0.79 to 1.89 h-1 at 275°C and from 0.91 to 3.78 h-1 at 300°C. The sample based on molybdenum showed the highest activity in hydrogenation and hydrodesulfurization. [ABSTRACT FROM AUTHOR]

This work presents an approach that expresses the Michaelis constant KaM and the equilibrium constant Kth of an enzymatic peptide hydrolysis based on thermodynamic activities instead of concentrations. This provides KaM and Kth values that are independent of any co-solvent. To this end, the hydrolysis reaction of N-succinyl-l-phenylalanine-p-nitroanilide catalysed by the enzyme α-chymotrypsin was studied in pure buffer and in the presence of the co-solvents dimethyl sulfoxide, trimethylamine-N-oxide, urea, and two salts. A strong influence of the co-solvents on the measured Michaelis constant (KM) and equilibrium constant (Kx) was observed, which was found to be caused by molecular interactions expressed as activity coefficients. Substrate and product activity coefficients were used to calculate the activity-based values KaM and Kth for the co-solvent free reaction. Based on these constants, the co-solvent effect on KM and Kx was predicted in almost quantitative agreement with the experimental data. The approach presented here does not only reveal the importance of understanding the thermodynamic non-ideality of reactions taking place in biological solutions and in many technological applications, it also provides a framework for interpreting and quantifying the multifaceted co-solvent effects on enzyme-catalysed reactions that are known and have been observed experimentally for a long time. [ABSTRACT FROM AUTHOR]

A new group-contribution approach involving systematic corrections for 1,4-non-bonded carbon-carbon and carbon-oxygen interactions has been proposed. Limits of the applicability of the method, associated with the highly branched structures, were established. Experimental data for enthalpies of formation in the liquid phase, enthalpies of vaporization, and enthalpies of formation in the gas phase for alkanes, alkenes, alkynes, alkylbenzenes, alkanols, ethers, ketones and aldehydes, carboxylic acids, esters, and carbonates were collected and critically evaluated through dynamic data evaluation as implemented in the NIST ThermoData Engine. An automatic procedure for molecular structure 'decomposition' was developed, and algorithms for the assessment of expanded uncertainties for the predicted property values were implemented. The combination of these software tools allows for ongoing improvements of the group-contribution parameter set as new experimental data become available. Fifty-two group-contribution parameters and their variances were evaluated for the proposed schema. Based on comparison of critically evaluated and predicted data for all classes of compounds studied, the performance of the new group formulation and associated parameters is superior to that originally suggested by Benson and the update by Cohen without an increase in the number of required parameters. [ABSTRACT FROM AUTHOR]