Cationic Oligomerization of the Pyrolysis C<Subscript>5</Subscript> Fraction

The cationic oligomerization of the pyrolysis C₅ fraction in the presence of catalyst systems based on AlCl₃, VOCl₃, BF₃ · O(C₂H₅)₂, and a Gustavson complex has been investigated. It has been shown that the use of the diisopropyl ether-modified Gustavson complex in the reaction makes it possible to synthesize fully soluble oligomers in high yields. The conversions of all the unsaturated components of the pyrolysis fraction to the oligomer at different durations of the oligomerization process have been determined. The synthesized oligomers are characterized by high unsaturation and exhibit the properties of film-forming compounds.     

Selective Hydrogenolysis of Glycerol to 1,2-Propylene Glycol on Ultrafine Copper Particles

Hydrogenolysis of glycerol to 1,2-propylene glycol at 200°C in the presence of Cu/Al₂O₃ catalysts prepared by coprecipitation from copper nitrate and aluminum nitrate using NaOH and NH₄OH has been studied. The kinetics of the reaction is described by the first-order rate law. It has been found that the selectivity for the target product for all catalyst samples is 98% and the activity of the catalysts depends on their synthesis conditions. By using X-ray diffraction analysis, transmission electron microscopy, energy dispersive X-ray analysis, and X-ray photoelectron spectroscopy, it has been revealed that the active phase of Cu/Al₂O₃ samples is made of particles with an average size of 20 to 140 nm, whose surface consisted of CuO and Cu₂O. The catalysts with different particle sizes the active phase but close chemical composition exhibits comparable activity (67.5 ± 5 h^–1mol^—1). This finding indicates that the hydrogenolysis reaction run in the presence of Cu/Al₂O₃ is not structure-responsive. A decrease in concentration of the Cu₂O phase of the catalyst leads to a decrease in the hydrogenolysis rate, thereby this indicating a higher activity of the Cu₂O phase in comparison with the CuO phase.     

Calculation of geometric structure,electronic characteristics,vibration frequencies,and thermodynamic properties of C12H20 alkyladamantanes

The structure of perhydroacenaphthene (I) and its conversion products 1,3-dimethyladamantane (II), trans-1,4-dimethyladamantane (III), cis-1,4-dimethyladamantane (IV), 1,2-dimethyladamantane (V), 1-ethyladamantane (VI), and 2-ethyladamantane (VII) of the general formula C₁₂H₂₀ has been studied using the Becke-Lee-Yang-Parr (B3LYP) hybrid method for the energy functional of the electron density with the 6–31G* basis set. Geometric and electronic characteristics of the compounds and their total energy, trans-formation energies, transformation entropies, and normal vibration frequencies have been calculated. The equilibrium constants determined for the isomerization of perhydroacenaphthene into products II-VII are consistent with experimental data.     

Gas separation characteristics of new membrane materials based on poly(ethylene glycol)-crosslinked polymers and ionic liquids

Gas transport characteristics (permeability and diffusion and solubility coefficients for CO₂, O₂, N₂, H₂) of new crosslinked membrane materials synthesized by copolymerization of poly(ethylene glycol) dimethacrylate and poly(ethylene glycol) methyl ether methacrylate in the presence of various ionic liquids have been studied. Comparison of the characteristics of specimens with and without ionic liquids has revealed that the presence of ionic liquids enhances the permeability of the membranes, especially to CO₂. It has been shown that the enhancement of the CO₂ permeability of films incorporating ionic liquid is due to an increase in CO₂ solubility and the increase in selectivity for pairs of gases containing CO₂ is determined by thermodynamic selectivity of separation.     

Synthesis and characterization of N-alkyl-2-aminopyridinum oligomers as pour point depressants for crude oil

The synthesis of N-decyl- (C10P), N-dodecyl- (C12P) and N-cetyl-2-aminopyridinum (C16P) oligomers was achieved by oxidative polymerization of N-decyl- (C₁₀), N-dodecyl- (C₁₂) and N-cetyl-2-aminopyridinium bromide monomers respectively in aqueous acid medium. Density function theory (DFT) was applied to recognize the reactive center in monomers used. The result of quantum calculations indicated that the oligomerization could proceed via open ring reaction. The obtained oligomers were characterized using FTIR and ¹H NMR spectroscopy. In addition, the XRD and SEM were used to investigate the morphology of the prepared oligomers. The thermal stability of the obtained oligomers was followed by thermogravimetric analysis (TGA). The conversion of these oligomers is ranged from 61 to 68% and the weight average molecular weights are closed to 3000?g?mol^?1. The surface tension of the synthesized oligomers was measured at different concentrations and temperatures. The efficiency of the synthesized oligomers in depressing the pour point of crude oil was investigated. The synthesized oligomers showed high efficiency as pour point dispersants.     

Exchange forms of binder-free granulated zeolites A and X: Synthesis and properties

Samples of crystalline aluminosilicates, the granules of which are intergrowths of zeolite A and X crystals with various degrees of exchange of Na⁺ cations for K⁺, Li⁺, H⁺, Mg²⁺, Ca²⁺, and La³⁺ in them, have been synthesized. The influence of the chemical nature and concentration of the exchange cation on the phase composition and the characteristics of the pore structure of the zeolite granules has been studied. The equilibrium adsorption capacities for H₂O vapor and CO₂ of binder-free granulated zeolites A and X in the Na, K, Li, H, Ca, Mg, and La-forms have been determined, and their adsorption activities in natural gas drying and removal of H₂S and CO₂ impurities in the dynamic mode at 20–25°C and atmosphere pressure have been examined. The relationships between the amount of the adsorbate and the type and concentration of exchange cations in the binder-free granulated zeolites A and X have been found.     

Base-catalyzed oxidation of poly (ethylene glycol) by alkaline permanganate: Part II. Kinetics and mechanistic of decomposition of coordination intermediate complex

The kinetics of decomposition of coordination polymer poly (ethylene glycol) intermediate complex [PEG-Mn^VIO₄^2-] which was formed during the progression of the relatively fast first stage for the oxidation of poly (ethylene glycol) (PEG) by alkaline permanganate have been investigated by conventional spectrophotometer. Pseudo first -order condition in the presence of [PEG] substrate as a synthetic polymer in large excess over [MnO₄^-] was showed first-order overall reaction kinetics. The influence of the alkali concentration on the decomposition rate constants indicated that the oxidation rates were increased with increasing the alkali concentration, therefore, the decomposition process was considered of base-catalyzed nature. The rate constant of decomposition was found to be 2.3 x10^-4 s⁻¹, whereas the deprotonation constant was 2.88 dm³ mol⁻¹ at 45 °C. The activation parameters have been calculated and found to be ΔH^≠ = 34.93 kJmol⁻¹; ΔS^≠ = −176.2 Jmo^l-K⁻¹ and ΔG^≠ = 90.96 kJmol⁻¹. The chemical structure of such synthesized acid-derivative of PEG was elucidated by elemental analysis and spectral data. The negative results of 2,4-dinitrophenyl hydrazine and hydroxylamine identified investigations along with (FTIR) spectra results indicated that the oxidation product is the acid derivative of poly (ethylene glycol) (ADPEG). The synthesis procedure of the acid-derivative of PEG (ADPEG) as the final oxidation product was described in detail. The product yield was found to be ~ 98%. It is found that the oxidation product (ADPEG) has a high tendency for chelation with most polyvalent metal ions in particularly the divalent metal ions forming their corresponding coordination polymer complexes. Therefore, this distinct property of the product renders it to be used as a chelating agent of high performance, non-toxicity and low cost compared with the chelating agents available in the markets. A suitable reaction mechanism for the decomposition in terms of electron-transfer nature was suggested and discussed.     

Synthesis,Physicochemical Properties,and Thermo-Oxidative Stability of Diesters of 5,7-Dimethyl-1,3-Adamantanediol and 5,7-Dimethyl-1,3-bis(Hydroxymethyl)adamantane

A series of diesters on the basis of 5,7-dimethyl-1,3-adamantanediol and 5,7-dimethyl-1,3- bis(hydroxymethyl)adamantane and C₃–C₁₀ aliphatic acids have been synthesized and their physicochemical and thermo-oxidative properties have been studied. The properties of the esters obtained have been compared to those of trimethylolpropane and neopentyl glycol esters.     

Hydroalkoxycarbonylation of isobutylene with polyhydric alcohols in the presence of catalytic systems based on palladium compounds and tertiary phosphines

The reaction of isobutylene hydroalkoxycarbonylation at low carbon monoxide pressures (??2.0 MPa) with ethylene glycol and glycerol in the presence of catalytic systems based on Pd and mono- and bidentate organic phosphines has been studied. The effect of different conditions of the reaction in the presence of the Pd(Acac)₂-PPh₃-TsOH catalyst system on the ratio of the products, mono- and diglycolides (mono-, di-and triglycerides) of isovaleric acid has been investigated. The relative catalytic activity of a number of binary and ternary systems based on synthesized Pd(Acac)₂, Pd(PPh₃)₄, and PdCl₂(PPH₃)₂ complexes has been determined.     

Phenol and dihydroxybenzene hydrogenation catalysts based on polyamide dendrimers and rhodium species

Heterogeneous catalysts based on rhodium nanoparticles and first- and second-generation poly(amidoamine) (PAMAM) dendrimers crosslinked with hexamethylene diisocyanate have been synthesized. It has been found that catalyst samples with a particle size of 0.88 to 1.96 nm, depending on the PAMAM dendrimer generation, are effective in the hydrogenation of phenol, hydroquinone, resorcinol, and pyrocatechol (85°C, 30 atm O₂, 2 h). In phenol hydrogenation, the selectivity for cyclohexanone is 100%. Cyclohexanone has not undergone further transformation under the reaction conditions. The main products of dihydroxybenzene hydrogenation have been trans-cyclohexanediols, with their proportion decreasing in the order: resorcinol > hydroquinone > pyrocatechol. The selectivity has been found to be 100% for 1,3-cyclohexanediol, 97–99% for 1,4-cyclohexanediol, and 33–91% for 1,2-cyclohexanediol. The catalysts based on the second-generation dendrimer have shown a high activity in dihydroxybenzene hydrogenation (TOF of 6600 to 35000 h^?1).     

Polarization and Polarizability of the Binary Mixtures of Tetraethylene Glycol With Benzene and Toluene at 20°C and 30°C

Abstract

The refractive index of the binary mixtures of tetraethylene glycol (TETEG) with benzene and toluene at 20°C and 30°C and atmospheric pressure have been measured at the whole composition range of mixtures. The polarizabiltiy (α), atomic polarization (P_a), solvated radii (r), and excess refractive indices (n^DE) were calculated and represented in figures versus concentration.     

Influence of resins and asphaltenes on the structural and rheological properties of petroleum disperse systems

The structural and rheological properties of resin-free model petroleum mixtures (MPM) with an asphaltene content of 0 to 6 wt % and the same mixtures with added 3.85 wt % petroleum resins have been investigated. The composition of the mixtures simulates the amount of the main hydrocarbon-group components and distillate fractions in light paraffin-base oils (ρ₄ ²⁰ = 747.7–789.1 kg/m³). Temperature–dynamic viscosity relationships for cooling the MPM have been obtained, most of which displayed abnormalities in the temperature range of ~40–60°C. Calculations of the viscous-flow activation energy (E _μ) have shown that there are abrupt changes in E _μ in this abnormality region, which are an indication of structuring processes. By means of Fourier-transform laser diffractomery of MPM solutions in kerosene, it has been found that the particle size of the petroleum mixtures is qualitatively related to the revealed abrupt changes in E _μ. It has been shown that these abnormalities correspond to the formation of paraffin–asphaltene associates and their existence is determined by the critical concentration of resins and asphaltenes in the mixtures.     

Base-catalyzed oxidation of poly (ethylene glycol) by alkaline permanganate: Part I. Kinetics and mechanism of formation of coordination intermediate complex

A spectrophotometric investigation has been applied to study the kinetics of oxidation of poly (ethylene glycol) (PEG) as a synthetic polymer by alkaline permanganate at a constant ionic strength of 1.0 mol.dm^?3. The reaction was found to proceed through two distinct measurable stages. The first stage was relatively fast and corresponding to the formation of coordination polymer intermediate complexes involving blue hypomanganate (V) and/or green manganate (VI) transient species. The influence of variable factors on the oxidation rates such as the concentration of permanganate ion and PEG substrate concentrations as well as the pH and ionic strength have been examined. Under the pseudo-first-order reaction conditions of [PEG] ? [MnO₄^?], the experimental results showed a first-order dependence in [MnO₄^?] and fractional first-order kinetics in each of [PEG] and alkali concentration. The oxidation process was of base-catalyzed nature where the oxidation rates were increased with increasing the alkali concentration. The observed first-order rate constant was found to be 1.1 ×10^?3 s^?1 with deprotonation constant of 0.72 dm³ mol^?1 at 45 °C. Blue hypomanganate (V) was detected for the first time by using a conventional spectrophotometer. The oxidation process has proceeded without the intervention of a free-radical mechanism. Colloidal manganese (IV) and the acid derivatives of PEG were identified as final oxidation products. The activation parameters of the second-order reaction have been calculated and found to be ΔH^≠ = 40.66 kJmol^?1; ΔS^≠ = ? 145.41 Jmo^l?K^?1 and ΔG^≠ = 83.99 kJmol^?1. A plausible reaction mechanism for oxidation based on the evaluated activation parameters and in good consistent with the observed kinetic data was suggested and discussed.     

Synthesis and gas separation properties of metathesis poly(5-ethylidene-2-norbornene)

High molecular weight metathesis poly(5-ethylidene-2-norbornene) (PENB) has been synthesized in the presence of the 1st generation Grubbs catalyst at a high monomer/catalyst ratio (3000/1 and higher). The yields of the corresponding polymer have been more than 90% at all monomer/catalyst ratios and molecular weights (M _w ) of PENB have been higher than 3 × 10⁵. The gas permeability of different gases (He, H₂, O₂, N₂, CO₂, and CH₄) through PENB films has been studied, and diffusivity and selectivity coefficients have been determined. It has been found that PENB is more permeable than unsubstituted metathesis polynorbornene and cycloalkyl-substituted polynorbornene dicarboximides, but it is less permeable than some Si-containing polynorbornenes. Despite the fact that PENB is more permeable than metathesis polynorbornene and cycloalkyl-substituted polynorbornene dicarboximides, it is close to these polymers in ideal selectivities for some gas pairs.     

Simultaneous determination of ethyl carbamate,chloropropanols and acrylamide in fermented products,flavoring and related foods by gas chromatography–triple quadrupole mass spectrometry

A simultaneous determination method was established by gas chromatography–triple quadrupole mass spectrometry (GC–MS/MS) for ethyl carbamate, acrylamide and chloropropanols (1,3-dichloropropane-2-ol (1,3-DCP), 2,3-dichloropropane-1-ol (2,3-DCP), 3-monochloropropane-1,2-diol (3-MCPD) and 2-monochloropropane-1,3-diol (2-MCPD)) in fermented products, flavoring and related foods. Ethyl carbamate-d₅, 1,3-DCP-d₅, 3-MCPD-d₅ and acrylamide-d₃ were used as isotope internal standards for ethyl carbamate, DCPs, MCPDs and acrylamide, respectively. The sample was extracted and cleaned in one single step by a combined clean-up column packed with Extrelut™ NT and primary secondary amine (PSA). The concentrated extract was directly injected without derivatization, separated by an Innowax (cross-bonded polyethylene glycol) capillary column and measured by GC–MS/MS. The calculated limits of detection (LODs) in the sample matrix were 1.8, 1.0, 2.1, 5.3, 5.1 and 5.0 μg kg⁻¹ for ethyl carbamate, 1,3-DCP, 2,3-DCP, acrylamide, 3-MCPD and 2-MCPD, respectively. The average recoveries in different matrices at three spiked concentration levels (20, 100 and 400 μg kg⁻¹) were 88.6–112, 92.6–103, 92.1–106, 86.2–107, 90.4–109 and 91.0–105% with relative standard deviations (RSDs) (Average RSDs in bracket) of 4.4–10.2 (6.4%), 3.7–7.3 (5.4%), 3.9–7.7 (5.2%), 4.4–9.3 (6.4%), 4.1–10.7 (6.3%) and 3.7–7.9% (5.6%), respectively. Two to six contaminants were simultaneously found in some of the soy sauce samples. Ethyl carbamate, acrylamide, 3-MCPD and 2-MCPD were found in the instant noodle flavoring. Trace levels (<12 μg kg⁻¹) of ethyl carbamate, acrylamide or 3-MCPD were detected in tomato sauce and salad dressing. Both ethyl carbamate and acrylamide were found in some of the curry products and Chinese yellow rice wine. Only ethyl carbamate was found in beer and grape wine.     

QUANTITATIVE SEPARATION AND EVALUATION OF FISCHER-TROPSCH REACTION PRODUCTS HAVING LOW 14C-ISOTOPIC ACTIVITY

ABSTRACT

A method has been developed to effect the separation of Fischer-Tropsch products, predominately hydrocarbons, into, first, alkane and alkene fractions, and, secondly, each of these fractions into their normal and branched components. Conditions for methods using a “dry” silica column for the first separation and molecular sieves for the second separation have identified that permit collection of sufficiently large samples for subsequent separations. The first separation has been effected so the normal to branched chain ratio has not been altered. Liquid chromatographic conditions have been found whereby the n-alkane fraction can then be separated to provide a pure sample of each alkane in the C₈ - C₂₄ carbon number range. The alkane fractions have been collected so that the ¹⁴C activity can be determined for each alkane.     

Joint aromatization of butane and hexane on alumina-platinum catalysts

It has been found that the joint aromatization of C₄ and C₆ alkanes proceeds during the conversion of a butane and hexane mixture on alumina-platinum catalysts. It has been shown that a necessary condition for realization of the joint aromatization is the presence of highly dispersed platinum as ionic species (Pt^σ) and “hard” Lewis acid sites (L_z) of a catalyst. It has been determined that an optimum L_z/Pt^σ ratio for joint conversion reaction of light alkanes is from 1 to 2.     

Synthesize and characterization of new polymeric surfactants based on nonionic maleate surfmer by catalytic bulk copolymerization with methyl methacrylate

Non-ionic maleate surfmer (M1) was prepared via ring opening reaction of maleic anhydride with hexanol followed by esterfaction with polyethylene glycol. The prepared surfmer was homo-polymerized and copolymerized with methyl methacrylate (M2) at different conditions using TiO₂ and V₂O₅ as catalysts in presence of O₂ or N₂. The chemical structure of the prepared surfmer, homo-polymer and copolymer were confirmed by FT-IR, ¹³C and ¹H NMR. The molecular weights of the prepared polymers were measured using Gel Permeation Chromatography (GPC) and their thermal gravimetric analysis (TGA) was determined. TGA indicated a higher thermal stability for the copolymers M1M2TN and M1M2VO relative to the pure polymethylmethacrylate (PMMA). The interfacial tension for the prepared surfmer and the copolymer was measured. The optimum conditions which resulted in 64.2% and 63.8% conversion were 20% w/w TiO₂ in N₂ and 10% w/w V₂O₅ in O₂ at 80?°C for 4?h with M1/M2 molar ratio of 1:1.     

Synthesis and evaluation of some derivatives of polysiloxanes

Silicone surfactants have been widely used in our daily life and many industrial fields on the basis of their unusual properties. Only in the past decades has the use of silicone as a hydrophobic building block for the preparation of surfactants become common. The recent trend to combine silicone, polyoxyalkylene and carbohydrate moieties in the same molecule has resulted in a plethora of new compounds with new properties.In this article, we report the preparation of a series of “glycopolysiloxanes” surfactants with different molecular weights. They were structurally characterized by IR, ¹H NMR and MS.Specifically, the critical micelle concentration (cmc), effectiveness of surface tension reduction (π_cmc), maximum surface excess (Γ_max), minimum surface area (A_min) and standard free energies of micellization (ΔG°_mic) and adsorption (ΔG°_ads) have been determined from aqueous surface tension measurements using Du-Nouy Tensiometer (KRUSS K6 type 4851) with a platinum ring. All the surfactants have good surface properties and have low cmc.The bacteriostatic power of these polymers was tested and compared under the same conditions in aqueous solution against common strains of Gram positive bacteria and strains of Gram negative bacteria.     

Synthesis and characterization of Ni-Mo catalyst using Jatropha curcas leaves as carbon support and its catalytic activity for hydrotreating of gas oil,Jatropha oil,and their blends

A novel carbon-based Ni-Mo catalyst has been synthesized successfully from Jatropha curcas leaves using boric acid as a surface modifying agent. The Ni-Mo catalyst prepared on Jatropha curcas leaves had shown BET surface area of 316 m²/g whereas the Ni-Mo catalyst prepared without boric acid activation had shown BET surface area of only 14 m²/g. XRD and SEM data have shown that the active catalyst particles such as Ni and Mo have been found to be uniformly distributed. The inventive catalyst was studied for hydrotreating of gas oil, Jatropha curcas oil and 20% Jatropha oil in gas oil at 370°C, 90 bar H₂ pressure, liquid hour space velocity of 1 h^?1, and gas-to-oil ratio of 500 Nm³/m³ and the results obtained were found to be comparable with that of the commercial Ni-Mo catalyst supported on alumina.