A new alkylate production process

A new technology for alkylation on solid AlkiRAN-GPN catalyst with process performance characteristics and an attained material balance competitive with existing sulfuric and hydrofluoric acid alkylation technologies is presented. Data on the effect such parameters as temperature, pressure, iso-butane: olefin ratio, and feedstock hourly space velocity (FHSV)) have on the process’s performance characteristics are given, and their optimum values are recommended. It is shown that using a sectioned reactor at a constant inlet iso-butane: olefin ratio ensures a higher internal ratio of these components and an increase in the total concentration of alkylate in the reaction products at a specified internal iso-butane: olefin ratio. This also lengthens the period of catalyst interregeneration with no losses in the process’s productivity and selectivity. The use of a zeolite based on faujasite in the rare-earth element–calcium form (REECaHY) and ultrastable zeolites as catalysts is substantiated. Higher values of olefin conversion and the alkyl gasoline yield are observed when these zeolites are used. To test the new technology, a demonstration plant of iso-butane alkylation with olefins on heterogeneous catalysts with an alkylate production capacity of 1 t/day is constructed. The results from studies are to be used in developing the basic design of an industrial plant. The construction of the first industrial plant of alkylation on a heterogeneous catalyst with an alkyl gasoline production capacity of 100000 t/year is planned at AO Gazprom Neft Moscow Oil Refinery.     

Kinetics of Sedimentation of a Coagulating Suspension

The coagulation–sedimentation kinetics in a spatially heterogeneous disperse system is theoretically analyzed. The expression for the suspension concentration c as a function of time t and depth h is obtained in the form c ～ t ^?ε h ^εν. The concentration of the dispersed phase formed in coagulant hydrolysis depends on the coagulant concentration c ₀ as c ～ c ₀ ^{? γ} . It is determined how the exponents in the expressions derived are related to the characteristics of the coagulation kinetics and the aggregate size distribution. The results obtained are compared with published experimental data.     

Mesostructure controllable ZSM-5 single crystals supported Pd/transition metal oxides: efficient and reusable catalysts for selective oxidation under aerobic conditions

Pd and transition metal oxides functionalized ZSM-5 single crystals with b-axis aligned mesopores (ZSM-5-OM-PdO _x -MO _x ) were prepared. ZSM-5-OM support was obtained from crystallization of aluminosilicate gels in the presence of cationic polymers. Characterizations indicate abundant nanopores and highly crystalline degree of ZSM-5-OM-PdO _x -MO _x , and active species of Pd and transition metals were homogeneously dispersed into ZSM-5-OM, which showed unique interactions and enhanced ability for activating oxygen. Catalytic tests showed that ZSM-5-OM-PdO _x -MO _x were highly active and reusable catalysts for selective oxidation of alcohols under aerobic and solvent free condition, which were much better than those of Pd/transition metal oxides functionalized ZSM-5, mesoporous silica of SBA-15, and activated carbon catalysts.     

Pilot tests of the microspherical aluminochromium KDI-M catalyst for <Emphasis Type="Italic">iso</Emphasis>-butane dehydrogenation

Results from pilot tests of microspherical aluminochromium KDI-M catalyst mixed with IM-2201 in a large-scale unit (Nizhnekamskneftekhim) for iso-butane dehydrogenation are discussed. Compared to KDI catalyst, its modified analogue KDI-M is more active and selective; the optimized grain-size composition and mechanical strength ensures higher yields of iso-butylene and longer nonstop operation (up to 400 days) of the reactor unit.     

Catalytic combustion of volatile aromatic compounds over CuO-CeO<Subscript>2</Subscript> catalyst

Ce_1?x Cu _x O₂ oxide solid solution catalysts with different Ce/Cu mole ratios were synthesized by the one-pot complex method. The prepared Ce_1?x Cu _x O₂ catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and H₂ temperature-programmed reduction (H₂-TPR). Their catalytic properties were also investigated by catalytic combustion of phenyl volatile organic compounds (PVOCs: benzene, toluene, xylene, and ethylbenzene) in air. XRD analysis confirmed that the CuO species can fully dissolve into the CeO₂ lattice to form CeCu oxide solid solutions. XPS and H²-TPR results indicated that the prepared Ce_1?x Cu _x O₂ catalysts contain abundant reactive oxygen species and superior reducibility. Furthermore, the physicochemical properties of the prepared Ce_1?x Cu _x O₂ catalysts are affected by the Ce/Cu mole ratio. The CeCu₃ catalyst with Ce/Cu mole ratio of 3.0 contains abundant reactive oxygen species and exhibits superior catalytic combustion activity of PVOCs. Moreover, the ignitability of PVOCs is also affected by the respective physicochemical properties. The catalytic combustion conversions of ethylbenzene, xylene, toluene, and benzene are 99%, 98.9%, 94.3%, and 62.8% at 205, 220, 225, and 225 °C, respectively.     

Glycerol Steam Reforming for Hydrogen Production over Nickel Supported on Alumina,Zirconia and Silica Catalysts

The aim of the work was to investigate the influence of support on the catalytic performance of Ni catalysts for the glycerol steam reforming reaction. Nickel catalysts (8 wt%) supported on Al₂O₃, ZrO₂, SiO₂ were prepared by the wet impregnation technique. The catalysts’ surface and bulk properties, at their calcined, reduced and used forms, were determined by ICP, BET, XRD, NH₃-TPD, CO₂-TPD, TPR, XPS, TEM, TPO, Raman, SEM techniques. The Ni/Si sample, even if it was less active for T?<600?°C, produces more gaseous products and reveals higher H₂ yield for the whole temperature range. Ni/Zr and Ni/Si catalysts facilitate the WGS reaction, producing a gas mixture with a high H₂/CO molar ratio. Ni/Si after stability tests exhibits highest values for total (70%) and gaseous products (45%) glycerol conversion, Y_H2 (2.5), S_H2 (80%), S_CO2 (65%), H₂/CO molar ratio (6.0) and lowest values for S_CO (31%), S_CH4 (3.1%), CO/CO₂ molar ratio (0.48) among all samples. The contribution of the graphitized carbon formed on the catalysts follows the trend Ni/Si (I _D /I _G ?=?1.34)?<?Ni/Zr (I _D /I _G = 1.08)?<?Ni/Al (I _D /I _G = 0.88) and indicates that the fraction of different carbon types depends on the catalyst’s support nature. It is suggested that the type of carbon is rather more important than the amount of carbon deposited in determining stability. It is confirmed that the nature of the support affects mainly the catalytic performance of the active phase and that Ni/SiO₂ can be considered as a promising catalyst for the glycerol steam reforming reaction.     

Impact of Chain Length on the Catalytic Performance in Hydroisomerization of <Emphasis Type="Italic">n</Emphasis>-Alkanes Over Commercial and Alkaline Treated *BEA Zeolites

The present paper highlights the influence of desilication of nanocrystal *BEA zeolites (CP811 and CP814E) by different alkaline treatments in presence of NaOH alone, NaOH?+?TPABr and NaOH?+?TBAOH, on the catalytic performance in the hydroisomerization reactions of n-alkanes (n-C₁₀, n-C₁₂ and n-C₁₄). The well-balanced catalyst was reached after impregnation of 1.5 wt% of Pt, where the activity and isomers selectivity was seen to be the maximum, knowing that the Pt content effect was studied on the CP811 zeolite catalyst. All the other catalysts were after impregnated by approximately 1.5 wt% of Pt. The improvement of the textural properties by means of desilication was not always accounting for the influence of the catalytic performance of the catalysts, but rather it may be the bifunctional characteristics in charge. The impact of chain length was investigated on the catalysts to study if the presence of the inter- and intracrystalline mesopores would account for better diffusion of larger molecules as, n-C₁₂ and n-C₁₄. It was found on the majority of the catalysts that the activity was high whether the chain length was, but the isomers selectivity was decreasing with chain length except on one catalyst that possesses high textural and bifunctional characteristics. Among the three n-alkanes studied, n-C₁₂ have marked the highest TOF values and lowest selectivity to isomers, a phenomenon attributed to the confinement effect that seems to increase the interaction of n-C₁₂ molecules with the acidic sites of the zeolites, apparently causing their strength to be higher. This effect was pronounced more with n-C₁₂ than the other two n-alkanes.

Graphical Abstract

Open image in new window

     

Effect of nitrogen to niobium atomic ratio on superconducting transition temperature of δ-NbN<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> powders

Powders of cubic niobium nitride δ-NbN _x with a particle size of below 20 μm were prepared by reactive diffusion at T = 1455?1475°C under nitrogen pressures of P ₁(N₂) = 0.1?3 MPa and P ₂(N₂) = 25 MPa. For these powders, the values of the stoichiometric coefficient x, lattice parameter a, and the superconducting transition temperature Tc were measured and the a(x), T _c(x) and T _c(a) functions were analyzed. The T _c values were found to linearly grow with increasing a (decreasing structure imperfection). A maximum value of T _c (15.8 K) corresponded to a maximum value of a (4.3934 Å). Maximain the a(x) and T _c(x) curves were found to correspond to a slightly substoichiometric nitride with x = 0.98. Having synthesized cubic niobium nitrides with 0.892 < x < 1.062, we managed to measure the dependences of a and T _c on x all over the almost entire homogeneity range for δ-NbN _x . Our a(x) and T _c(a) functions were found to reasonably agree with those previously reported for SHS-produced δ-NbN _x powders.     

Fe-doped LaCoO<Subscript>3</Subscript> perovskite catalyst for NO oxidation in the post-treatment of marine diesel engine’s exhaust emissions

New post-treatment process for marine diesel engine exhaust emissions was proposed by combining NO oxidation and wet scrubbing technology for the simultaneous removal of SO_X, NO_X and PM. NO, insoluble in aqueous scrubbing absorbent, is preferentially oxidized to NO₂, which then turns fully soluble in it. Fe substituted LaCo_1-xFe_xO₃ perovskite catalysts were developed for NO oxidation to NO₂. The catalysts were prepared by co-precipitation method and analyzed with XRD, XRF, BET, FT-IR, NO-TPD and XPS techniques. Crystal structure change from rhombohedral to orthorhombic was observed with the increased amount of Fe substituted in the B site of the perovskite by XRD analysis. From FT-IR and NO-TPD analysis, nitrate on perovskite species was found to be the active species for NO oxidation. Quantitative analysis was performed within the prepared catalysts. Catalytic activity was measured using a packed bed reactor operated at 150–400 °C, atmospheric pressure and with gas hourly space velocity (GHSV) of 20,000 h^-1 using a simulated exhaust gas composed of NO 400 ppm, O₂ 10% balanced with N2. Formation of Fe⁴⁺ cation enhanced the redox property as well as the mobility of the lattice oxygen present in the perovskite catalysts, confirmed by XPS analysis. Reaction mechanism of NO oxidation on Fe substituted LaCo_1-xFe_xO₃ was discussed based on Mars-van Krevelen mechanism.     

CO and CO<Subscript>2</Subscript> methanation over Ni catalysts supported on alumina with different crystalline phases

The effect of alumina crystalline phases on CO and CO₂ methanation was investigated using alumina-supported Ni catalysts. Various crystalline phases, such as α-Al₂O₃, θ-Al₂O₃, δ-Al₂O₃, η-Al₂O₃, γ-Al₂O₃, and κ-Al₂O₃, were utilized to prepare alumina-supported Ni catalysts via wet impregnation. N₂ physisorption, H₂ chemisorption, temperature-programmed reduction with H₂, CO₂ chemisorption, temperature-programmed desorption of CO₂, and X-ray diffraction were employed to characterize the catalysts. The Ni/θ-Al₂O₃ catalyst showed the highest activity during both CO and CO₂ methanation at low temperatures. CO methanation catalytic activity appeared to be related to the number of Ni surface-active sites, as determined by H₂-chemisorption. During CO₂ methanation, Ni dispersion and the CO₂ adsorption site were found to influence catalytic activity. Selective CO methanation in the presence of excess CO₂ was performed over Ni/γ-Al₂O₃ and Ni/δ-Al₂O₃; these substrates proved more active for CO methanation than for CO₂ methanation.     

Investigation of the fast relaxation in glass-forming selenium by low-frequency Raman spectroscopy

The low-frequency Raman spectra of liquid and vitreous selenium are investigated. It is demonstrated that the temperature dependence of the intensity of the fast relaxation at the glass transition temperature (T _g = 308 K) exhibits a specific feature. This feature manifests itself in a sharper increase in the intensity at temperatures T > T _g as compared to that observed at lower temperatures. The intensities of the fast relaxation at the critical temperature T _c are evaluated by the extrapolation of the linear dependence to the temperature range T > T _g in the framework of the mode-coupling theory. The new results obtained for selenium are compared with the available data for other glass-forming materials (boron oxide, toluene, arsenic sulfide). It is shown that, for all the glasses under investigation, the parameter describing the contribution of the fast relaxation to the Raman spectrum takes on the same value at the critical temperature T _c and is approximately equal to 0.3.     

Assessing the technological value of coal in coking

Coking coal of the same rank from different countries and fields may be distinguished in terms of use value by rating on the basis of seven technological and petrographic characteristics that determine the coke yield and properties: the ash content A^d; the total sulfur content S_t^d; the yield of volatiles V^daf; the plastic-layer thickness y; the vitrinite reflection coefficient R_o; the content of vitrinite-group macerals Vt; and the basicity index B_b. A range of values and a rating (on a scale from 1 to 10) are established for each of these parameters. Each rating corresponds to a particular score (from 0.1 to 1.0). Ranges of A^d, S_t^d, Vt, and B_b are established for the whole metamorphic series, while ranges of V^daf, y, and R_o are established for individual ranks and groups of ranks. Altogether, 105 coking coals from Ukraine, Russia, the United States, Australia, and Canada that are used at Ukrainian coke plants are investigated. The range of rating scores and their mean values are determined for individual coal ranks and groups. As an example, three bituminous coals from Ukraine, the United States, and Australia are compared by the proposed method. This method permits objective assessment of the technological value of coal within a single rank and the selection of the best purchase option.     

Solid-phase synthesis and characterization of rare-earth chromates

Simple chromates(V) MCrO₄ (M = Sc, Y, Gd, Er, or Yb) and chromate(V) vanadates Gd(CrO₄) _x (VO₄)_{1 ? x} have been synthesized by a solid-phase method. All compounds crystallize in the xenotime-type structure, space group I4₁/amd, Z = 4. The unit cell parameters have been calculated as follows: for GdCrO₄, a = 7.209(5) Å, c = 6.318(4) Å; for ErCrO₄, a = 7.088(2) Å, c = 6.231(1) Å; for YbCrO₄, a = 7.034(1) Å, c = 6.205(2) Å; for YCrO₄, a = 7.108(3) Å, c = 6.254(3) Å; and for ScCrO₄, a = 7.012(2) Å, c = 6.188(2) Å. Symmetry D _2d , established for the CrO₄ tetrahedron during the Rietveld structure refinement, is verified by IR spectroscopy. The MCrO₄ simple chromates are paramagnets; their magnetic moments range from 1.7 to 8.1 μ _B .     

Lipids of the Tail Gland,Body and Muzzle Fur of the Red Fox, <Emphasis Type="Italic">Vulpes vulpes</Emphasis>

The tail gland of the red fox (Vulpes vulpes) secretes lipids containing volatile terpenes used in social communication. We have analysed lipids extracted from fur of the tail gland, body (flanks) and muzzle of foxes. GC–MS showed a novel group of iso-valerate and tiglate monoesters of alkane-1,2-diols (C18:0–22:0). There was also a larger group of Type II diesters in which a second, longer chain, fatty acid (FA) was attached to the free alcohol group. LC–MS showed the full range of diol diesters, mostly C36:0–50:0, with smaller amounts of the corresponding mono-unsaturated tiglate esters. An additional group of diesters with higher MW (C49:0–62:0) containing two long-chain FA was present in the lipids of body and muzzle fur. After saponification and GC–MS, 98 fatty acids were characterized as their methyl esters. Apart from the C5 FA, most were saturated n-, iso-, anteiso- or other methyl-branched FA (C12:0–28:0) whose structures were determined by a combination of their mass spectra and Kovats retention indices. Several FA have not previously been found in nature or in vertebrates. Thirty-four alkane-1,2-diols were found as their TMS derivatives, mostly n-, iso- or anteiso-isomers of C16:0–25:0. The tail gland had the greatest amount of wax esters, from a greater variety of FA and diols, but lacked the esters with two long-chain FA. These findings show that fox skin lipids comprise mono- and di-esters of alkane-1,2-diols, and exhibit enormous complexity due to the diversity of their constituent FA, diols and the many possible isomers of their esters.     

Predicting the classification characteristics of coal. Part 3. Gross calorific value of dry,ash-free coal

For 63 samples of Ukrainian, Russian, and imported coal, equations for predicting the gross calorific value Q_s^daf on the basis of the following coal characteristics are developed: W^a, O_d^daf, Q_s^af, and C_ar. The error is within the standard tolerances (σ ≤ 0.3 MJ/kg). With sufficient accuracy, Q_s^daf may be predicted from equations based on petrographic characteristics such as the vitrinite reflectance, the content of liptinitegroup minerals, and the sum of lean macerals (I + 2Sv/3). In these equations, the coefficients correspond to the heat of combustion of the vitrinite components at different metamorphic stages, the liptinite, and the lean macerals.     

IR Spectroscopy in Rank and Group Assignment of Coal

The possibility of express determination of the characteristics V _IR ^daf , R_{o, IR}, y_IR, ΣLC_IR, and A _IR ^d used in the ranking of coal on the basis of IR spectroscopy is assessed for a specific example: Kuznetsk coals of different maceral composition and metamorphic development. The IR characteristics are compared with values obtained by standard methods (V^daf, R_{o, r, y}, ΣLC, and A^d).     

Probing the Structural,Electronic, and Magnetic Properties of Ag<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript>V (<Emphasis Type="Italic">n</Emphasis> = 1–12) Clusters

The structural, electronic, and magnetic properties of Ag _n V (n?=?1–12) clusters have been studied using density functional theory and CALYPSO structure searching method. Geometry optimizations manifest that a vanadium atom in low-energy Ag_nV clusters favors the most highly coordinated location. The substitution of one V atom for an Ag atom in Ag _n?+?1 (n ≥ 5) cluster modifies the lowest energy structure of the host cluster. The infrared spectra, Raman spectra, and photoelectron spectra of Ag _n V (n?=?1–12) clusters are simulated and can be used to determine the most stable structure in the future. The relative stability, dissociation channel, and chemical activity of the ground states are analyzed through atomic averaged binding energy, dissociation energy, and energy gap. It is found that V atom can improve the stability of the host cluster, Ag₂ excepted. The most possible dissociation channels are Ag _n V?=?Ag?+?Ag _n???1V for n?=?1 and 4–12 and Ag _n V?=?Ag₂?+?Ag _n???2V for n?=?2 and 3. The energy gap of Ag _n V cluster with odd n is much smaller than that of Ag _n?+?1 cluster. Analyses of magnetic property indicate that the total magnetic moment of Ag _n V cluster mostly comes from V atom and varies from 1 to 5 μ _B. The charge transfer between V and Ag atoms should be responsible for the change of magnetic moment.     

Stability of polymer structures based on fullerene C<Subscript>60</Subscript> under their oxidation with oxygen

A comparative study of the oxidative destruction of the monomer face-centered cubic (FCC) lattice and various polymer [dimeric (D), orthorhombic (O), tetragonal (T), and rhombohedral (R)] phases of C₆₀ in an atmosphere of oxygen has been performed in the temperature range of 100–500°C with the use of a flow microunit connected to a gas chromatograph. From direct measurements of the content of CO₂ in the gaseous products of destruction, the temperature dependences of oxidation rates are measured for the materials under study. It has been established that, with respect to stability against oxidative destruction, different forms of C₆₀ may be arranged as follows: the monomer FCC phase of C₆₀ > D > O > T > R. The reasons behind this tendency are discussed.     

Time dependence of the aggregation of star-shaped poly(2-isopropyl-2-oxazolines) in aqueous solutions

The paper concerns the analysis of time t _eq required to equilibrium state achievement in aqueous solutions of star-shaped poly(2-isopropyl-2-oxazolines) (PiPrOx) after changing temperature. The discussed data were obtained for PiPrOx differing in arm number and length. For all samples, high t _eq values, half an hour at least, were obtained because of rather high intramolecular density. The dependence t _eq on temperature displayed maximum near the phase separation beginning due to the aggregate growth and redistribution of scattering particles. The maximum times t _eq increased symbatically with arm number and length. The higher energy of the hydrogen bond formed by deuterium isotope leads to the growth of the t _eq values as compared to solutions in H₂O.     

Relations between the reflection coefficients of the basic groups of macerals: A review

Quantitative relations are found between the structural and chemical characteristics of macerals of the basic coal groups (vitrinite Vt, inertinite I, liptinite L), on the one hand, and their reflection coefficients R _r and the corresponding dispersions σ _R , on the other. For coal of a particular metamorphic stage, the reflection coefficient declines in the series I > Vt > L, on account of the reduction in aromatic chemical structure and in the degree of condensation of the aromatic blocks. In the metamorphic series, the reflection coefficients of the macerals rise; the values for Vt and L at intermediate stages converge. The dispersion of the reflection coefficients (and hence the reflectograms) is due to the spread in characteristics of the chemical structure of the coal’s organic content, as confirmed by calculations for the vitrinite of D, G, Zh, and K coal.