Exhaustive schemes for refining C<Subscript>3</Subscript>-C<Subscript>4</Subscript> hydrocarbon fractions

Exhaustive schemes for efficient refining of the C₃-C₄ hydrocarbon fraction using zeolite type Y catalysts to obtain a high-octane additive are proposed. Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 5, pp. 6–7, September–October, 2008.     

Cycloaddition of cage and polycyclic diazo compounds to C<Subscript>60</Subscript> fullerene catalyzed by Pd(acac)<Subscript>2</Subscript>-2PPh<Subscript>3</Subscript>-4Et<Subscript>3</Subscript>Al

Spirohomofullerenes were synthesized by cycloaddition of cage and polycyclic diazoalkanes generated in situ by oxidation of hydrazones of camphor, 2-adamantanone, and cholestane-3-one to C₆₀ fullerene in the presence of the Pd(acac)₂-2PPh₃-4Et₃Al three-component catalyst. It was found that the spiro-homofullerenes obtained from hydrazones of 2-adamantanone and cholestane-3-one and C₆₀ fullerene do not undergo thermal isomerization to the corresponding spiro-methanofullerenes.     

Selective dimerization of styrene to 1,3-diphenylbutene-1 in the presence of [(acac)Pd(PAr<Subscript>3</Subscript>)<Subscript>2</Subscript>]BF<Subscript>4</Subscript>/BF<Subscript>3</Subscript>OEt<Subscript>2</Subscript> catalytic systems

Selective dimerization of styrene to 1,3-diphenylbutene-1 in the presence of [(acac)Pd(PAr₃)₂]BF₄ + BF₃OEt₂ catalytic systems, where R = C₆H₅, o-CH₃C₆H₄, p-CH₃C₆H₄, or o-CH₃OC₆H₄, has been studied. Under the optimal conditions (B/Pd = 8, T = 75°C, R = C₆H₅), the conversion of styrene to the products exceeds the conversion for the known analogs and reaches 1.5 tons of styrene/g-atom of palladium with amounts of dimers and trimers of 91 and 9%, respectively. The dimers consist of up to 100% 1,3-diphenylbutene-1 with a trans/cis isomer ratio of 95/5.     

Effect of CO<Subscript>2</Subscript> on the oxidation of cyclohexene by H<Subscript>2</Subscript>O<Subscript>2</Subscript> using Co<Subscript>1.5</Subscript>PW<Subscript>12</Subscript>O<Subscript>40</Subscript> catalyst

Oxidation of cyclohexene by cheap and environmentally friendly oxidants, namely H₂O₂ and CO₂ has been catalyzed by Co_1.5PW₁₂O₄₀. It has been found that the main products of the oxidation are 2-cyclohexen-l-one (enone), 2-cyclohexen-l-ol (enol) and 1, 2-cyclohexanediol (diol) with the enone as the major product. Oxidation by CO₂ along with H₂O₂ remarkably increased the conversion compared to that by CO₂ and H₂O₂ separately. This might be due to the fact that CO₂ increases the percarbonate species (HCO₄ ^?) responsible of the oxidation by oxygen transfer, which indicated that the CO₂/H₂O₂ mixture is a useful reagent system. The decrease of both the selectivity of the enone and epoxide in favor of that of diol at higher conversions indicated that the diol was formed from the epoxide by consecutive reaction and/or directly from cyclohexene.     

Isomerization of <Emphasis Type="Italic">n</Emphasis>-hexane over bifunctional Pt/SO<Subscript>4</Subscript>/ZrO<Subscript>2</Subscript> catalysts

The catalytic properties of model Pt/SiO₂ and Pt/Al₂O₃ catalysts and their physical mixtures with SO₄/ZrO2 in the reaction of n-hexane isomerization have been studied. Significant effects of the influence of the platinum state on the characteristics of isomerization on the catalysts and their physical mixtures with SO₄/ZrO₂ have been revealed. The observed changes in catalytic performance of the mixed catalysts have been explained from the position of a bifunctional mechanism with the participation of ionic platinum promoting the formation of hydride ions, which play an important role in the activation of transformations of intermediates in isomerization reactions.     

Mono- and Bimetallic Mo(W)S<Subscript>2</Subscript>/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> and Mo(W)S<Subscript>2</Subscript>/SBA-15 Hydrotreating Catalysts Based on SiMo<Subscript>12</Subscript> and SiW<Subscript>12</Subscript> Heteropoly Acids

Mono- and bimetallic Mo(W)S₂ catalysts supported on γ-Al₂O₃ and SBA-15 have been prepared using the Keggin heteropoly acids (HPAs) H₄SiMo₁₂O₄₀ and H₄SiW₁₂O₄₀. The catalyst samples have been analyzed by temperature-programmed reduction with hydrogen, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. Catalytic properties have been examined in the joint hydrotreating of dibenzothiophene and naphthalene on a flow-through unit. It has been shown that the use of mesoporous silica SBA-15 as a support can reduce the average length of Mo(W)S₂ particles from 4.9 to 3.7 nm and increase the average number of layers and the particle size of the active phase, changes that lead to an increase in catalytic activity by a factor of ~3 relative to the alumina-supported counterparts. The use of a mixture of SiMo₁₂HPA and SiW₁₂HPA for preparing MoW catalysts leads to a significant enhancement of catalytic activity, which is apparently due to the formation of mixed active sites.     

Liquid––liquid phase equilibrium in saturated hydrocarbon – arenes C<Subscript>6</Subscript>-C<Subscript>8</Subscript> – mixed extractant systems

Experimental data are reported on liquid–liquid equilibrium in saturated hydrocarbon – C₆-C₈ arene – mixed extractant (triethylene glycol–sulfolane–water) pseudoternary systems of varying composition at 50°C. It was shown that increasing the sulfolane:TEG ratio from 21.7:78.3 to 60:40 changes the character of the bimodal curve in the phase diagram from the open to the closed type. As a result, for the same ratio of extractant and feedstock, all of the extraction indices – the degree of extraction, distribution coefficients, and arene content in the extractant – improved and the hydrocarbon fractionation factors increased.     

Conversions of mixtures of propane and benzene on Pt,Re/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> + H-zeolite systems

The conversion of C₆H₆: C₃H₈C mixtures on mixed catalysts composed of the metal catalysts Pt,ReOx/Al₂O₃ and zeolites Y, M, and ZSM-5 in the H form was studied. The products of benzene dehydroalkylation by propane and propane dehydrogenation products are formed at 180–350°C. It has been shown that propane is activated on the metal catalysts and C₆H₆ interacts with the zeolites yielding the C₆H₇ ⁺ intermediate, which acts as an agent of proton transfer from a zeolite to a metal catalyst, and another intermediate C₉H₁₃⁺ (I). Cumene, alkylbenzenes, and propene are formed as a result of the conversion of I. A comparison of the results of the conversion of these mixtures on the composite catalysts with different zeolites shows that the formation of cumene and propene is thermally controlled and the formation of the other products is kinetically controlled. It has been concluded that the coupling of the redox properties of the metal catalysts with the acid-base properties of the zeolite catalysts facilitates the low-temperature transformations of the mixtures.     

Photochemical oxidation of thiophene by O<Subscript>2</Subscript> in an organic two-phase liquid-liquid extraction system

Photochemical oxidation products and the kinetics of thiophene in an n-octane/acetonitrile extraction system using O₂ as an oxidant was studied. The results could be used as a reference for the oxidative desulfurization of gasoline because thiophene is one of the main components containing sulfur in a fluid catalytic cracking (FCC) gasoline. Thiophene dissolved in n-octane was photodecomposed and removed into the water phase at an ambient temperature and atmospheric pressure. A 500-W high-pressure mercury lamp (main wavelength 365 nm, 0.22 kW m⁻²) was used as the light source for irradiation and air was introduced by a gas pump to supply O₂. Thiophene could be photooxidized to SO₄ ²⁻ and CO₂. The desulfurization yield of thiophene in n-octane is 65.2% for a 5-h photoirradiation under the conditions of air flow at 150 m min⁻¹ and V(n-octane): V(acetonitrile) = 1:1. It can be improved to 96.5% by adding 1.5 g L⁻¹ artificial zeolite, which is an absorbent for O₂. Under such conditions, the photooxidation kinetics of thiophene with O₂ is of the first order with an apparent rate constant of 0.6297 h⁻¹ and a half time of 1.10 h. The sulfur content can be depressed from 800 to 28 ppm. The text was submitted by the authors in English.     

Differentiation of jurassic and cretaceous Kalmykia crudes based on C<Subscript>14</Subscript>-C<Subscript>16</Subscript> diamantanes

The distribution of hydrocarbons of diamond-like structure – C₁₀-C₁₃ adamantanes and C₁₄-C₁₆ diamantanes – in Kalmykia condensate lying in Cretaceous and Jurassic deposits was investigated by chromatography–mass spectrometry. It was shown that Jurassic and Cretaceous crudes can differ with respect to the relative distribution of C₁₅-C₁₆ methyl- and dimethyldiamantanes.     

Ethylene oligomerization in the presence of ZrO(OCOR)<Subscript>2</Subscript>-Al(C<Subscript>2</Subscript>H<Subscript>5</Subscript>)<Subscript>2</Subscript>Cl-Modifier catalytic system

The kinetics of ethylene oligomerization and molecular-mass distribution of resulted oligomers on ZrO(OCOR)₂-Al(C₂H₅)₂Cl and ZrO(OCOR)₂-Al(C₂H₅)₂Cl-modifier catalyst systems, where the modifier was CCl₄, vinyl acetate, or zinc stearate, were studied depending on the modifier: ZrO(OCOR)₂ and Al(C₂H₅)₂Cl: ZrO(OCOR)₂ molar ratios, ethylene pressure, temperature, and modifier nature.     

Study of a mass transfer-reaction model for SO<Subscript>2</Subscript> absorption process using LAS/H<Subscript>2</Subscript>SO<Subscript>4</Subscript> solution

A regenerative absorption process for removal of SO_x from FCC off-gas using LAS/H₂SO₄ solution as absorbant was studied and pilot-plant experiments were carried out. A mass transferreaction model for the SO₂ absorption process was established based on pilot-plant experiments, and the concentration distribution of components in the liquid film, and the partial pressure and mass transfer rate of SO₂ along the height of the absorption tower, was calculated from this model. The numerical simulation results were compared with the experimental results and proved that the model can be used for describing the SO₂ absorption process.     

Expanding Feedstock Resources for Manufacture of Vaseline

An alternative to petrolatum in feedstock for manufacture of medicinal Vaseline from Azerbaidzhan crudes was sought. The feedstock, adsorbent, and processing conditions selected increase the yield of Vaseline from 35–40 to 70–75% while reducing formation of difficult to use wastes.__________Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 3, pp. 18 – 19, May – June, 2005.     

Kinetics of cyclohexene hydrocarbalkoxylation with cyclohexanol catalyzed by the Pd(PPh<Subscript>3</Subscript>)<Subscript>2</Subscript>Cl<Subscript>2</Subscript>-PPh<Subscript>3</Subscript>-<Emphasis Type="Italic">p</Emphasis>-toluenesulfonic acid system

The reaction kinetics of cyclohexene hydrocarbalkoxylation with cyclohexanol catalyzed by the Pd(PPh₃)₂Cl₂-PPh₃-p-toluenesulfonic acid system was studied over the temperature range 363–393 K. The reaction rate was found to be a nonlinear function of the Pd(PPh₃)₂Cl₂ concentration or a nonmonotonic function of the PPh₃ and cyclohexanol concentrations or p _CO. The experimental data were interpreted in terms of a mechanism that involves ion pairs containing alkyl and acyl palladium complexes of the cationic type as intermediates. Based on the quasi-steady-state approximation, a rate equation was obtained to adequately describe the experimental data. The rate equation parameters were estimated using the least squares technique. The apparent activation energies of these parameters were determined. The heats of formation of Pd(PPh₃)₂(C₆H₁₁OH)₂, Pd(PPh₃)₂(CO)₂, and Pd(PPh₃)₄ complexes from Pd(PPh₃)₂(C₆H₅CH₃)₂ were estimated. A symbatic change in these values with the donor-acceptor properties of ligands was demonstrated.     

Sensitivity analysis of CO<Subscript>2</Subscript> sequestration in saline aquifers

Carbon capture and storage (CCS) technology has been considered as an important method for reducing greenhouse gas emissions and for mitigating global climate change. Three primary options are being considered for large-scale storage of CO₂ in subsurface formations: oil and gas reservoirs, deep saline aquifers, and coal beds. There are very many large saline aquifers around the world, which could make a big contribution to mitigating global warming. However, we have much less understanding of saline aquifers than oil and gas reservoirs. Several mechanisms are involved in the storage of CO₂ in deep saline aquifers, but the ultimate goal of injection of CO₂ into the aquifers containing salt water is to dissolve the CO₂ in the water. So it is important to study the solubility trapping and sensitivity factors of CO₂ in saline aquifers. This paper presents results of modeling CO₂ storage in a saline aquifer using the commercial reservoir simulator ECLIPSE. The objective of this study was to better understand the CO₂/brine phase behavior (PVT properties) and quantitatively estimate the most important CO₂ storage mechanism in brine-solubility trapping. This would provide a tool by performing theoretical and numerical studies that help to understand the feasibility of CO₂ geological storage. A 3-dimensional, 2-phase (water/gas) conceptional reservoir model used finite, homogenous and isothermal formations into which CO₂ is injected at a constant rate. The effects of main parameters were studied, including the vertical to horizontal permeability ratio k _v/k _h, salinity, and residual phase saturations. The results show that the vertical to horizontal permeability ratio has a significant effect on CO₂ storage. Moreover, more CO₂ dissolves in the brine at lower k _v/k _h values.     

A Composite Additive for “Heavy” Gas-Condensate Diesel Fuel

A composite additive that decreases the cloud and solid points of GShZ gas-condensate diesel fuel, stable condensate “heavy” bottoms, to the values required by GOST 305–82 for grade “3– 45” petroleum diesel fuel, was developed from domestic feedstock. This significantly improves the performance properties of gas-condensate diesel fuel.__________Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 4, pp. 26 – 28, July – August, 2005.     

Dissociation behavior of （CH4 ＋ C2H4） hydrate in the presence of sodium dodecyl sulfate

Separation of a mixture of CH4+C2H4 gas by forming hydrate in ethylene production has become of interest,and the dissociation behavior of(CH4+C2H4) hydrate is of great importance for this process. The hydrate formation rate could be increased by adding a small amount of sodium dodecyl sulfate(SDS) into water. In this work,the kinetic data of CH4(18.5 mol%) +C2H4(81.5 mol%) hydrate decomposition in the presence of 1000 mg·L-1 SDS at different temperatures and pressures were measured with the depressurizing m...     

Conversion of dimethyl ether into C<Subscript>2</Subscript>-C<Subscript>4</Subscript> olefins on zeolite catalysts

The effect of the nature of the metal introduced into HZSM-5 on the properties of the catalysts for the synthesis of olefins from dimethyl ether was studied. By means of the ammonia temperature-programmed desorption technique, it was shown that a decrease in the total amount of acid sites increases the selectivity for lower olefins. As the ratio of the medium to strong acid sites increases, the yield of olefins increases. The effect of the nature of gaseous additives in the feedstock on the selectivity for lower olefins was studied at T = 340°C, p = 0.1 MPa, and ν ₀ = 2000 h^?1.     

Precise model for estimating CO<Subscript>2</Subscript>—oil minimum miscibility pressure

The CO₂—oil minimum miscibility pressure (MMP) is an important parameter for screening and selecting reservoirs for CO₂ injection projects. For the highest recovery, a candidate reservoir must be capable of withstanding an average reservoir pressure greater than the CO₂—oil MMP. Knowledge of the CO₂—oil MMP is also important when selecting a model to predict or simulate reservoir performance as a result of CO₂ injection. This paper, presents a new alternating conditional expectation “ACE”-based model for estimating CO₂—oil MMP. The ACE algorithm estimates the optimal transformation that maximizes the correlation between the transformed dependent variable “CO₂—oil MMP” and the sum of the transformed independent variables that represent reservoir temperature and different components of oil composition. Predicted values of the CO₂—oil MMP from the developed ACE-based model were compared with the experimental and calculated values from the most common correlations reported in the literature for CO₂—oil MMP prediction. The results showed that the ACE-based model is superior to other commonly used correlations. Regarding other correlations, the ACE-based model yielded the highest correlation coefficient (0.9878), the lowest average relative error (0.7428%), and the lowest standard deviation of error (1.2265). The text was submitted by the author in English.     

Study of Separation Behavior of Activated and Non-Activated MOF-5 as Filler on MOF-based Mixed-Matrix Membranes in H<Subscript>2</Subscript>/CO<Subscript>2</Subscript> Separation

In this study, cubic and tetragonal structures of MOF-5 (C-MOF-5 and T-MOF-5) were successfully synthesized, characterized and incorporated into cellulose acetate (CA) polymer matrix in the range of 6, 9 and 12 wt % to fabricate mixed matrix membranes (MMMs). The effects of smaller pore size of T-MOF-5 and more ZnO molecules in T-MOF-5, on the H₂ and CO₂ permeation properties of C-MOF-5/CA and T-MOF-5/CA MMMs were investigated. The all novel MMMs were prepared using the solution casting method and characterized by FTIR, TGA and SEM. SEM images as well as results of FTIR and TGA analyses confirmed good adhesion between both MOF-5s and CA matrix. Addition of both C-MOF-5 and T-MOF-5 into the CA improved the gas transport properties of the CA, especially in H2 separation. The H₂/CO₂ selectivity continued the increasing trend at 9 wt % and did not significantly reduce even at 12 wt % due to good adhesion between both MOF-5s and CA. The highest H₂/CO₂ selectivity was obtained at 12 and 9 wt % loading of C-MOF-5 and T-MOF-5, respectively. By changing the filler from C-MOF-5 to T-MOF-5, the increasing and reducing of adsorption site of H₂ and CO₂ (respectively), and also reducing in pore size, caused the appearance of H₂ permeability to not change much but the CO2 permeability to reduce. Accordingly, the H₂/CO₂ selectivity in all T-MOF-5/CA MMMs is higher than that in all C-MOF-5/CA MMMs. According to obtained results, the activated MOFs (i.e., C-MOF-5 in this study) are not always the best choices for separation process.