Vol 92, No 7 (2018)

A stable CuZnAl slurry catalyst for the synthesis of ethanol from syngas has been developed by adjusting the heat treatment conditions of the complete liquid-phase method. The activity evaluation results showed that the CuZnAl catalyst, when heat-treated under a high pressure and temperature, was a stable catalyst for the synthesis of ethanol. The selectivity of ethanol using the CuZnAl slurry catalyst, which was heat-treated at 553 K under 4.0 MPa, increased continuously with time and was stable at approximately 26.00% after 144 h. The characterization results indicated that the CuZnAl slurry catalyst heat-treated under high pressure conditions could facilitate the formation of a more perfect structure with a larger specific surface area. The prepared catalyst contained a balance of strong and weak acid sites, an appropriate form of Cu₂O and a high Cu/Zn atomic ratio at the catalyst surface, providing its stability in ethanol synthesis from syngas.

Metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide], has been used as a chloroacetanilide herbicide to control annual grass weeds and broadleaf weeds in corn, cotton, peanuts, soybeans and beans. In this paper, aRS-metolachlor has been used as a model to investigate the reaction of OH radicals with atmospheric metolachlor. The reaction mechanism was obtained at the MPWB1K/6-311 + g(3df,2p)//MPWB1K/6-31 + g(d,p) level of theory and the rate constants were deduced over the temperature range of 180–370 K using canonical variational transition state (CVT) theory with the small curvature tunneling (SCT) method. The atmospheric lifetime of aRS-metolachlor determined by OH radicals is about 3.97 h, which indicates that it can be degradaded in the gas phase easily and doesn’t have the potential for long-range transport.

A Fe-promoted Pt-Fe/Al₂O₃ catalyst was prepared by water/oil microemulsion. The physicochemical properties of the Pt/Al₂O₃ and Pt-Fe/Al₂O₃ catalyst were characterized by TEM, SAED, XRD, XPS, BET, ICP, and CO-chemisorption. The introduction of Fe could promote the formation of a catalytic active center Pt, enhance electron enrichment of Pt, and improve the degree of Pt dispersion. The effect of Fe on the catalytic performance of the Pt/Al₂O₃ catalyst was investigated by the liquid-phase hydrogenation of m-chloronitrobenzene to m-chloroaniline. The Fe-promoted Pt-Fe/Al₂O₃ catalyst was extremely active and more selective than the Pt/Al₂O₃ catalyst (conversion from 57.7 to 96.3%, selectivity from 98.5 to 99.2%).

Heterogeneous nucleation in disperse systems with metastable disperse phases plays an important role in the mechanisms of environmental and technological processes. The effect the concentration and activity of particles that initiate the formation of a new phase have on nucleation processes in such systems is considered. An approach is proposed that allows construction of a spectrum of particle activity characterizing the features of nucleation in a sample, based on the fraction of crystallized droplets depending on the level of supercooling and the use of Weibull’s distribution. The proposed method is used to describe experimental data on the heterogeneous nucleation of methane hydrate in an emulsion in a water–decane-methane system.

Enthalpies of dissolution of crystalline diclofenac sodium are measured in water and in aqueous solutions of KOH at 298.15 K via direct calorimetry in a wide range of concentrations. The acid–base properties of diclofenac sodium are studied via spectrophotometry at ionic strengths of I ~ 0 and I = 0.1 (KNO₃) and a temperature of 298.15 K. The concentration and thermodynamic dissociation constants are determined. The standard enthalpies of formation are calculated for diclofenac sodium, and for the products of its dissociation in an aqueous solution.

Comparative calculations based on the use of a homodesmotic reaction (HDR)—an isodesmic process with the additional requirement for group balance—is used to analyze the thermochemical characteristics of cyclic organic compounds exemplified by bicyclo[2.1.0]pentene-2. To avoid confusion in selecting HDRs, an algorithm is developed for determining the HDR basis, i.e., the set of all possible independent homodesmotic reactions. The algorithm for constructing the set of HDRs is based on an analysis and transformations of the bond graph of groups for the investigated chemical compound. The use of graph theory allows us to automate the procedure for deriving the basis of homodesmotic reactions, and to obtain a visual geometric interpretation of the basis, which is important for subsequent physicochemical analysis. The energetics of bicyclo[2.1.0]pentene-2 is investigated using the proposed approach, and the independent basis of HDRs is found to include 19 formal transformations. Standard enthalpies for the test compound and the participants of homodesmotic reactions are calculated using the G3 composite approach. Thermochemical analysis of the obtained data allows us to determine the standard enthalpy of formation of the bicycle (Δ_fH° = 336.4 kJ/mol) and value Δ_fH° of a number of cyclic and acyclic alkenes and alkadienes that are products of theoretical decomposition of the test compound. The proposed method is shown to be extremely effective in analyzing the effects of nonbonded interactions in the structure of organic molecules. The ring strain energy of the bicycle is calculated or the test compound: E_S = 295.2± 2.2 kJ/mol.

The infinite dilution diffusion coefficients (D₁₂) of methanol, ethanol, 1-propanol, 1-butanol and 1-pentanol in supercritical CO₂ (scCO₂) at 313.2 K and 10–16 MPa were simulated by molecular dynamics (MD) simulation. The microscopic structure was also analyzed by calculation of the radial distribution function, coordination number (CN) between the center mass of solute and solvent molecules, and the average number of hydrogen bonding of this system. In infinite dilute solution, the probability of forming hydrogen bond between alkanol molecules is greatly reduced relative to pure alkanol fluid, and the weak hydrogen bonds formed between alkanol and CO₂ molecules. In general, this work provides a reliable simulation method for transfer properties of solutes in scCO₂. The prediction data were provides for the design and development of chemical processing. The results are helpful for one to deeper understand the relationship between microscopic structures of fluid and its transfer properties.

Mass spectra of positive and negative MALDI ions of the series of fullero[C₆₀] tetrahydropyridines with different substituents in a heterocycle are systematically studied for the first time. All mass spectra contain C₆₀ fullerene peaks as a result of the reduction of fullero[C₆₀]tetrahydropyridines. The intensities of the protonated molecular ions’ [M + H]⁺ peaks are highest in the mass spectra of positive ions of the studied compounds, while molecular radical ion [M]⁺ is less intense. The intensities of the peaks of molecular radical ion [M]^– are highest in the mass spectra of the negative ions. The [C₆₀C₂H₅] ions formed during the decay of the molecular ions with the detachment of neutral nitrile molecules is characteristic of all compounds. Using DFT quantum–chemical calculations (PBE/3z), the energies of the highest (HOMO) and lowest unoccupied molecular orbitals (LUMO) are determined for fullero[C₆₀]tetrahydropyridines with substituents in the heterocycle.

The results from studies of the interface boundaries between metals (copper and iron) and gel electrolyte based on methacrylic copolymers are organized systematically. In contrast to processes in liquid electrolytes, a number of key features of the reactions that occur at such interfaces are revealed: a diffusion limiting stage; a lack of reverse reactions; and the formation of coordination compounds of metal ions with the functional groups of polymers, the stabilities of which are several orders of magnitude greater than that of coordination with their low–molecular weight counterparts. It is shown that processes which employ polymeric organogels can be used for the careful cleaning of the metal surfaces, and for the formation of a desired phase composition on the latter.

The growth of liquid phase nuclei on the surface of some crystals was shown to differ from that described in the classic theory of capillarity. The surface of the base face of a silver iodide crystal is completely covered with a monomolecular water film already in unsaturated vapors, and the wetting conditions of the substrate are determined by the hydrophobic properties of the film surface, but not the crystal surface itself. The mechanism by which the monomolecular film is held on the surface of crystalline silver iodide was studied by the Monte Carlo method at the molecular level. It was found that the adhesion of the film to the surface of the base face of the crystal was by hydrogen bonding with the ions of the second crystallographic layer of the substrate, and the film was thermodynamically stable even in unsaturated water vapor. The film hydrophobicity is due to the deficiency of hydrogen bond donors on its surface. The nanostructural elements on the surface of the aerosol particle can neutralize the hydrophobic properties of the film and thus serve as nucleation centers.

The pattern of changes in the salting-out ability of the salts of nontransition metals and ammonium is established with respect to aqueous solutions of ethoxylated nonylphenols. The anions in the salt play a key role in the process, while cations have almost no effect on the salting-out ability of the salts of singly charged anions. The salting-out effect of anions diminishes in the order \({\text{PO}}_{4}^{{3 - }}\), \({\text{SO}}_{4}^{{2 - }}\), Cl⁻, \({\text{NO}}_{3}^{ - }\), Br⁻, and I⁻. Na⁺, K⁺, \({\text{NH}}_{4}^{ + }\), and Ba²⁺ cations have no pronounced salting-in effect. The salting-in effect diminishes along with the charge of the cation in the order Al³⁺, Mg²⁺, and Li⁺. It is shown that the salting-out ability of salts diminishes as the degree of surfactant ethoxylation grows.

The effect hydrotropic additives (salts of aromatic acids and choline chloride) have on the micelle-forming properties (the critical concentrations of micelle formation and the Krafft temperature) of cationic surfactants, and on the solubilization capability of mono- and dicationic surfactants toward such hydrophobic compounds as a Sudan I spectral probe and curcumin natural dye, is considered. The factors that govern solubilization capacity, e.g., the structure of the head group of surfactants, the nature of the solubilizate and hydrotropic additives, and the pH of the medium are determined.

Dielectric constant measurements of glycol-formamide binary solutions with various concentrations have been carried out at different temperatures. The dielectric measurement has been achieved at 100 MHz frequency using a sensor which is based on frequency domain reflectomery technique. The excess dielectric constant, Kirkwood correlation factor and Bruggeman factor has also been reported for the binary mixtures. The results show that the dielectric constant of the mixtures increases with increase in the volume fraction of formamide and decreases with increase in temperature. The study also confirms the presence of intermolecular interaction, hydrogen bonding and orientation of the dipoles in the binary mixtures.

The adsorption of bovine serum albumin and bovine hemoglobin on silicalite-1 and monolayers of lecithin and cholesterol on a silicalite surface is investigated. Adsorption isotherms are obtained, and limit values of adsorption are determined that are 90, 75, and 60 mg/g for BSA and 35, 27, and 25 mg/g for hemoglobin on samples of silicalite, cholesterol/silicalite, and lecithin/silicalite, respectively. In the lecithin/silicalite system, proteins are adsorbed on both the lipid and silicalite. In the cholesterol/silicalite system, proteins are adsorbed only on the lipid monolayer. According to IR spectroscopy data, adsorption increases the part of disordered fragments in the secondary structure of protein.

The heat capacities and volumes of dimethylsulfoxide (DMSO) solutions of barium and cadmium iodides at 298.15 K were measured by calorimetry and densimetry. The standard partial molar heat capacities \(\bar {C}_{{p,2}}^{^\circ }\) and volumes \(\bar {V}_{2}^{^\circ }\) of BaI₂ and CdI₂ in DMSO were calculated. The standard heat capacities \(\bar {C}_{{p,i}}^{^\circ }\) and volumes \(\bar {V}_{i}^{^\circ }\) of barium and cadmium ions in DMSO at 298.15 K were determined.

It is found during the curing of a cyanate ester oligomer that there are such features as a step and a maximum in the frequency dependences (in a range of 10⁻²−10⁵ Hz) of the real parts of the complex electric conductivity and loss tangent, respectively. In the frequency range where these features are observed, the diagrams of complex electric modulus are semicircles with centers near the abscissas. Subsequent analysis shows these features are due to the formation of the microphase of the intermediate product, carbamate.