Overview of Catalytic Methods for Production of Next Generation Biodiesel from Natural Oils and Fats
Key words: биодизель, «зеленый дизель», дезоксигенирование, жирные кислоты
Production of biodiesel from natural oils and fats can be achieved using various technologies briefly discussed in this review. A particular appealing concept for production of green diesel is selective catalytic deoxygenation of renewables leading to diesel fuel products. This reaction can be performed over Pd on active carbon supports with saturated and unsaturated fatty acids and their derivatives.
Key words: сверхкритические флюиды, химическое и фазовое равновесие, фазовые диаграммы, критическая точка, многокомпонентная смесь, неидеальность, теплофизические свойства, монотерпены, a-пинен, гетероазеотропы, математическое моделирование
The mathematical and calculating models were developed to solute the specific research problems on thermodynamics of multicomponent and multiphase mixtures. The features of chemical and phase equilibria were examined both for the ideal-gas approximation and the non-ideality. The conditions of equilibrium phase stability were studied for multi phase systems. The calculation results of specific phase diagrams, binodal and spinodal are demonstrated for the appropriate reaction mixtures. The new interpretation of mathematical model was suggested for the localization of critical point, especially for fixed multicomponent chemical mixtures. The new variation of classical homotopy method was developed for the soluting of complex nonlinear equations systems, which are the princi ples of concerned mathematical models. The some anomalous phase profiles and the critical curves were analyzed to demonstrate the necessity of taking into account the pointed features at the planning of experiments, the reactor parameters calculations. The examples of specific multicomponent non-ideal mixtures indicate the possibility of thermodynamic and thermophysical behaviors calculations (entropy, enthalpy and heat capacity; thermal reaction effect, adiabatic warming up). It was noted that the cubic state equations are quite suitable for the prediction of property deviations from the ideal-gas state and can be used for the prognosis of behavior anomaly at the critical point surrounding.
Key words: сверхкритические флюиды, фазовое поведение, полые многоканальные волокна
New method to monitor phase behavior of mixtures at high pressures and temperatures was developed on basis of continuous sampling by use of glass capillary. Such technique gives opportunity not to disturb equilibrium in the system and to get information about phase state in continuous flow systems at different stages of process. As a detector the flame-ionization detector (FID) was chosen due to the fact that our solvents are not flammable and will not give signal. Method was validated using two different setups on systems: water.ethanol and CO<sub>2</sub> acetone.
Key words: субкритический диоксид углерода, нанопористые структуры, адсорбция и конденсация в порах, сдвиг критической точки, КАРС-диагностика
Coherent anti-stocks Raman scattering spectra measured in the range of <em>Q</em>-branch of ν<sub>1</sub> vibrational transition are used to reveal the state of carbon dioxide in nanopores of Vicor glass. The measurements were carried out in a high pressure optical cell at room (20.5 °C) and subcritical (30.5 °C) temperatures and CO<sub>2</sub> pressures up to saturation value P<sub>sat</sub> for each temperature. In addition to the main spectral component assigned to gaseous CO<sub>2</sub> molecules, the second, low frequency component appears in the spectra at pressures close to P<sub>sat</sub>. This second component is determined by the contribution of CO<sub>2</sub> molecules inside pores. Spectral deconvolution taking into account the interference of these two bands allows one to estimate spectral features of the
second (low-frequency) component for each temperature. The bandwidth of lowfrequency component decreases with CO<sub>2</sub> pressure at 20.5 °C, which is caused by transition of CO<sub>2</sub> from adsorbed stated to condensed state in the pore. At subcritical temperature 30.5 °C the spectral width of the second component is independent of pressure and corresponds to the value measured in free volume at supercritical conditions, which is likely due to the low-temperature shift of critical point in nanopores.
Key words: сверхкритическая флюидная экстракция, Reynoutria sachalinensis, медленная индукция флуоресценции, термолюминесценция
The effect of supercritical fluid (SF) extracts of giant knotweed Reynoutria sachalinensis on photosynthetic activity of Vicia faba L. bean leaves was studied by slow fluorescence induction (SFI) and thermoluminescence (TL) methods. The treatment of plants with extracts led to the enhancement of their photosynthetic activity. The maximum stimulating effect was observed for extract obtained using carbon dioxide with 2% of ethanol as co-solvent. The observed stimulating effect is assumed to be bound with increasing of carries pool of the photosynthetic electron transport chain of plant leaves by quinonic compounds flux into plant cells.
Key words: сверхкритический диоксид углерода, ультрадисперсный политетрафторэтилен, растворимость, модель Чрастиля,модель Мендеза-Сантьяго, модель Бартла
The solubility and separation of low molecular mass fractions of ultrafine
polytetrafluoroethylene (UPTFE) in supercritical carbon dioxide (SC-CO<sub>2</sub>) are<br>
measured using static method in the temperature and pressure ranges of 318÷383 K
and 10÷70 MPa, respectively. The solubility isotherms follow the behavior typical for
«solid.supercritical fluid» systems, i.e. the solubility increases with pressure, due to
increasing of SC-CO<sub>2</sub> pressure, and temperature. The experimental data are discussed
in terms of three different density-based models proposed by Chrastil, Bartle and
Mendez-Santjago. It was concluded that two last models well predict the shape of
experimentally observed dependences.
Key words: асфальтен, сорбция газов, разбавленный раствор
A thermodynamic description of methane and ethane sorption by asphaltenes from petroleum gas condensate is proposed. Experimental data demonstrate that the major part of gases is dissolved in asphaltenes. The accounting of this effect suggests the
averaged equation of state for sorbed gas identical by shape to the Vant-Hoff equation for diluted solutions. The developed approach that utilizes the analogy to gas dissolution in liquids leads to an efficient thermodynamic method for calculation of natural gas components sorption by asphaltenes at supercritical temperatures and pressures corresponding to the conditions of real exploitation of gas deposits.<br>
Key words: инактивация, микроорганизмы, Escherichia coli, Deinococcus radiodurance, Candida albicans, сверхкритический диоксид углерода
The kinetics of inactivation of E. coli and D. radiodurance bacteria and imperfect fungi
Candida albicans was studied in compressed and supercritical carbon dioxide. The
possibility of decreasing concentration of the survived cells by 5—7 orders of magnitude
was demonstrated.
Key words: сверхкритический диоксид углерода, хлорид палладия, комплексы с органическими лигандами, растворимость, катализатор, пропитка, регенерация
Solubility of palladium chloride complexes with organic ligands in supercritical carbon
dioxide (SC-CO<sub>2</sub>) is studied. The possibility of utilization of SC-CO<sub>2</sub> for synthesis
and regeneration of supported palladium catalysts is examined. The solutions of palladium
chloride complexes with organic ligands in SC-CO<sub>2</sub> were used for deposition of the
catalyst active component. The catalyst sample deactivated in the reaction (acethylene
hydrogenation in ethane-ethylene mixture) was also regenerated in SC-CO<sub>2</sub> in a wide
range of parameters. The comparison of specific surface area values and activities of<br>
fresh, used (deactivated) and regenerated samples demonstrates high competitive
power of the suggested methods utilizing SC-CO<sub>2</sub> in comparison with traditional
ones used for catalyst regeneration.
Key words: сверхкритическая флюидная импрегнация, пористые стекла, синтетический опал, наночастицы серебра, плазмонный резонанс
Silver-containing nanocomposites are fabricated by impregnation of Vycor glass (4 nm
pore diameter) and synthetic opals (40 nm interstice size) with Ag(hfac)COD
(cyclooctadiene complex of silver hexafluoroacetylacetonate) silver precursor dissolved
in supercritical carbon dioxide, and studied with optical absorption spectroscopy, atomic
force microscopy and electron spin resonance (ESR) technique. Plasmon resonances
of Ag nanoparticles at 420-430 nm were revealed for Ag(hfac)COD impregnated
Vycor glass and opal matrixes after thermal treatment on air at temperatures above<br>
50 °C. Shapes of plasmon resonances for both types of samples are conditioned by the
morphology of their porous space in which silver nanoparticles are formed in the
course of thermal treatment after the SCF impregnation. Paramagnetic species Cu(hfac)<sub>2</sub>
(copper hexafluoroacetylacetonate) are used as spectroscopic probes for ESR
measurements of precursor distribution in Vycor glass and opal after their SCF
impregnation.<br>
Key words: субкритическая вода, вератрол, параформ, циклотривератрилен, циклотетравератрилен, масс-спектрометрия ESI, ЯМР
Interaction of veratrol and paraform in subcritical water is studied and two macrocyclic
compounds — cyclotriveratrilene and cyclotetraveratrilene (in 94 : 6 ratio) - are
obtained. Their formation is proved using a series of analytical procedures, including
mass-spectrometry with electrospray ionization (ESI-MS) and nuclear magnetic
resonance spectroscopy. Also, the formation of trimercation-tetramer type adduct of
the above macrocycles was detected by ESI-MS method.
Key words: онвекция Рэлея-Бенара, критическая термодинамическая точка, уравнения Навье-Стокса, численный и физический эксперимент
Two problems, the thermal gravity convection in a horizontal layer caused by heating from bellow and the unsteady-state heat transfer in a closed domain heated from boundaries, are considered for demonstrating characteristic features of heat transfer<br>
in a supercritical fluid. The isoentropic equilibrium of a compressible fluid is considered with the use of the van der Waals equation of state. The results of calculations are generalized, and the characteristic features of the convective heat transfer are discussed for the case of a supercritical fluid beyond the threshold of hydrostatic stability. The results of numerical and experimental studies of the relaxation of density and temperature perturbations caused by changing the wall temperature are presented. A set of Navier-Stokes equations supplemented with the equation of state for a perfect or a van der Waals gas was used for the calculations.
Key words: сверхкритические флюиды, измерение плотности, высокотемпературные среды высокого давления, фазовое поведение
High temperature vibrating density gauge (VDG) for chemically active media is developed. The VDG operational principle is based on registration and analysis of natural frequencies of high pressure U-tube capillary filled with the media under
study. The location of the capillary inside the thermostat possessing ±0.1 °C temperature accuracy, that enables density measurements and phase behavior study of aggressive media at pressure and temperature ranges 0.1÷50 MPa and 20÷500 °C, correspondently. Carbon dioxide density measurements performed with the VDG below, near and above its critical point (31 °C), as well as water density measurements at temperatures up to 375 °C demonstrated good agreement to the data derived from interactive database of NIST (National Institute of Standards and Technology). Density data for water-methanol binary mixture at temperatures up to 300 °C are obtained.
Key words: субкритическая вода, глауцин, дес-глауцин, ЯМР, ESI MS
The isomerization of non-racemic mixture of glaucine isomers into des-glaucine was
held in subcritical water media under 200-300°С with the yeld 53 %. The structure of the
product was proved with nuclear magnetic resonance spectroscopy (NMR) and
electrospray ionization (ESI-MS).
Key words: сверхкритический флюид, коэффициент извлечения нефти, термобарические условия
An experimental setup for studying the displacement of oil in a wide range of pressures
(up to 20 MPa) and temperatures (up to 373 K), that reflects thermobaric, geological,
and physico-chemical conditions in real oil-beds and parameters of displacing agents
is constructed. The results of experimental displacement of kerosene by supercritical
carbon dioxide at 313 ÷ 353 K and 7 ÷ 12 MPa demonstrate a high efficiency of this
technology for the output of low-viscosity oils.<br>
Key words: сверхкритические и водно-спиртовые экстракты, асцидии, <em>Halocynthia aurantium</em>, биотестирование, морские ежи, эмбрионы, экзогаструляция, инфузории
<em>Strongylocentrotus intermedius</em> is studied. It is showen that water-alcohol extract has no
remarkable effect onto gametes, process fertilization, development of embryo and
larvae of sea urchin. If the SC extract is added during the gamete fusion, the fertilization
and cell-division of blastomers are not affected, but the gastrulation becomes abnormal —
the exogastrulas are formed. Moreover, during the cultivation of embryo in a cultural
medium with SC extracts, the growth of Infusoria is depressed. It is likely that the
origin of differences in the biological effects of SC and water-alcohol extracts ought to
look for in peptide or secondary metabolite fractions, since no distinct differences in
li pid fractions are detected.
Key words: сверхкритический флюид, антирастворитель, фазовая диаграмма, быстрое расширение, RESS, наночастицы, полиизобутилен, полистирол, модификация
On the experimental test bench Thar RESS-100-2 Base the dispersion process of
polyisobutylene in the range of temperatures 45 ÷ 120 °C and pressures 100 ÷ 350 bar
was investigated; the particle size was 30 ÷ 1000 nm. The possibility of managing the
particle size by varying of the process parameters was revealed. The new method of
polymer particles modification during the rapid solution expansion was suggested. In
the modification process the effect of agglomeration is suppressed and the particles are
covered by modifier (NaCl). The availability of application of superctitical fluid antisolvent
to the dispersion of polymers to nanoparticles is based. The experimental test
bench for this method is described. Catching method for polymer nanoparticles formed
in antisolvent was suggested. While dispersing polystyrene in the system “tolyene -
polystyrene - supercritical carbon dioxide” under pressure 40 ÷ 150 bar and temperature