Narrow Fractions Research Articles

Systematic identification and distribution analysis of olefins in FCC slurry oil

In response to the chemical industry's eco-friendly and high-value-added requirements, FCC slurry oil (SO) has been used as a raw material for novel solid carbon materials. As one of the most important chemically active intermediates and products in the FCC process, olefins may have a significant impact on the quality of the carbon materials produced. However, the existence and distribution of olefins have not been discussed. In this paper, olefinic hydrocarbons were first innovatively identified as important compounds that do exist in SO, and their distributions in sub-fractions below 500 °C, classified with the types and carbon numbers, were analyzed. However, there are great limitations for the existing analytical methods in the distribution detection of olefins in the whole fractions of heavy oils. In order to solve this problem, a newly-developed analytical method has been developed. Two different separation techniques were implemented to separate SO into six sub-fractions and eight group compositions, according to boiling point and molecular polarity respectively, before the analysis of olefin distribution for higher accuracy. The proposed method has been further verified by the GC × GC-TOFMS method and proved to have superior reliability. The olefinic carbons in the fraction of 350–400 °C possess the highest content among the detected narrow fractions, up to 1.55%, which decreases gradually with the increase of boiling points, and the first three sub-fractions between 350–470 °C take most of the olefinic carbons in SO, reaching around 74%.

Magnetic Fractions of PM2.5, PM2.5–10, and PM10 from Coal Fly Ash as Environmental Pollutants

Characterization of magnetic particulate matter (PM) in coal fly ashes is critical to assessing the health risks associated with industrial coal combustion and for future applications of fine fractions that will minimize solid waste pollution. In this study, magnetic narrow fractions of fine ferrospheres related to environmentally hazardous PM2.5, PM2.5–10, and PM10 were for the first time separated from fly ash produced during combustion of Ekibastuz coal. It was determined that the average diameter of globules in narrow fractions is 1, 2, 3, and 7 μm. The major components of chemical composition are Fe2O3 (57–60) wt %, SiO2 (25–28 wt %), and Al2O3 (10–12 wt %). The phase composition is represented by crystalline phases, including ferrospinel, α-Fe2O3, ε-Fe2O3, mullite, and quartz, as well as the amorphous glass phase. Mössbauer spectroscopy and magnetic measurements confirmed the formation of nanoscale particles of ε-Fe2O3. Stabilization of the ε-Fe2O3 metastable phase, with quite ideal distribution of iron cations, occurs in the glass matrix due to the rapid cooling of fine globules during their formation from mineral components of coal.

Assessment of Selected Characteristics of Enrichment Products for Regular and Irregular Aggregates Beneficiation in Pulsating Jig

Article concerns problem of jig beneficiation of mineral aggregates and focuses especially on problem of separation of hard-enrichable materials. Investigative programme covered tests in laboratory and semi-plant scale and material with different content of regular and irregular particles, along with various particle size fractions, was under analysis. Two patented solutions were utilized as methodological approach and densities and absorbabilities of individual products were determined and major novelty of approach consist in separate beneficiation of regular and irregular particles. Results of laboratory investigations showed that more favorable separation effectiveness was observed for the narrow particle size fractions of feed material. In terms of absorbability difference between separation products from I and IV layer was 0.4–0.5% higher for regular particles, and up to 0.5% higher for irregular grains. Differences in densities of respective products were 0.1% higher for regular particles. Results of semi-plant tests confirmed the outcomes achieved in laboratory scale. The qualitative characteristics of separation products in terms of micro-Deval and LA comminution resistance indices were one category higher for regular particles, and two categories higher for irregular grains, comparing to the raw material.

Composition analysis of aromatics-rich extraction oil from FCC slurry

The extracted oil of intermediate base FCC slurry is split into eight narrow fractions with a boiling point interval of 20°C by vacuum distillation. The aromatic composition and constitution of these narrow fractions were determined by measuring their density, carbon residue and kinematic viscosity as well as elemental analysis, 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and comprehensive two-dimensional gas chromatography and time-of-flight mass spectrometry (GC×GC TOF MS). The results indicate that the density, carbon residue and kinematic viscosity of each narrow fraction increases with the increase of boiling point, in particular with a boiling point higher than 420°C. The aromatics consist of mainly tricyclic and tetracyclic aryl hydrocarbons in the narrow fractions with a boiling point lower than 440°C; the content of pentacyclic aromatics increases rapidly with the increase of boiling point over 440°C, though the pentacyclic aromatics are also present in the narrow fractions with a boiling point of 400–420°C. The aromatics in the FCC slurry are highly-condensed and contain a small amount of short-alkyl groups. The heteroatomic compounds in the narrow fractions include mainly sulfur- and oxygen-containing compounds, whereas the content of nitrogen- and halogen-containing compounds is very low.

ОЦЕНКА ВОЗМОЖНОСТИ ПОЛУЧЕНИЯ РАСТВОРИТЕЛЯ С НИЗКИМ СОДЕРЖАНИЕМ АРОМАТИЧЕСКИХ УГЛЕВОДОРОДОВ В АО «АНХК»

. In connection with the emerging demand for gasoline solvent with a low content of
 aromatic hydrocarbons we carrier out the analysis of intermediate products obtained in JSC " ANHK " 
 suitable for the producing of the solvent. The most suitable for the separation of the fraction are gaso line fractions producing from the hydrogenation product of the hydrocracking of light vacuum gas oil 
 and the hydrogenation product of high conversion hydrogenation of the heavy middle distillate frac tions. We performed work on the recovery of a narrow fraction of gasoline solvent and its tests for 
 compliance with the requirements.

Age affects the strain-rate dependence of mechanical properties of kelp tissues.

The resistance of macroalgae to hydrodynamic forces imposed by ambient water motion depends in part on the mechanical properties of their tissues. In wave-swept habitats, tissues are stretched (strained) at different rates as hydrodynamic forces change. Previous studies of mechanical properties of macroalgal tissues have used either a single strain rate or a small range of strain rates. Therefore, our knowledge of the mechanical properties of macroalgae is limited to a narrow fraction of the strain rates that can occur in nature. In addition, although mechanical properties of macroalgal tissues change with age, the effect of age on the strain-rate dependence of their mechanical behavior has not been documented. Using the kelp Egregia menziesii, we measured how high strain rate (simulating wave impingement) and low strain rate (simulating wave surge) affected mechanical properties of frond tissues of various ages. Stiffness of tissues of all ages increased with strain rate, whereas extensibility was unaffected. Strength and toughness increased with strain rate for young tissue but were unaffected by strain rate for old tissue. Young tissue is weaker than old tissue and, therefore, the most susceptible to breakage from hydrodynamic forces. The increased strength of young tissue at high strain rates can help the frond resist breaking when pulled rapidly during wave impingement, when hydrodynamic forces are largest. Because breakage of young tissue can remove a frond's meristem and negatively impact the survival of the whole kelp, strain-rate dependence of the young tissue's strength can enhance kelp's survival.

Composition of phenolic compounds in wastewater from the fixed-bed gasification of Baishihu coal

Crude phenols extracted using organic solvent from the wastewater of a typical fixed-bed gasification process was used as a raw material, and the distillation range was analyzed. The wide and narrow fractions of the raw material derived from distillation range analysis were cut using a real boiling point distillation device. The phenolic compounds in the different fractions were then qualitatively and quantitatively analyzed by gas chromatography after derivatization pretreatment. The yield of the < 290 °C fraction was 68.50% (mass fraction). A total of 33 effective phenolic compounds were identified in this fraction, and the percentage of identified phenols was nearly 80%. The contents of eight phenolic compounds were high, with phenol being the most abundant (26.34%) followed by catechol (13.44%). The contents of the remaining six abundant phenols ranged from 4% to 8%. The sum of the contents of m-cresol and p-cresol exceeded 12%, and the content of 5-indenol was nearly 8%. The yield of the fraction rich in low-grade phenols (< 230 °C) was 35.40%. The content of phenol in this fraction was more than 40%, the total content of cresol was over 23%, and the total content of m-cresol and p-cresol was nearly 20%. At room temperature, the 235–245 °C and 245–260 °C fractions were white crystals in which the catechol content was approximately 50%, and the 5-indenol content was more than 10%. The contents of these two high-value-added phenolic compounds are low in typical coal tar, making them difficult to extract. However, due to their strong polarity and good water solubility, catechol and 5-indenol are enriched in gasification wastewater by water selection, allowing their further extraction.

Burn time and combustion regime of laser-ignited single iron particle

An improved particle generator based on electrodynamic powder fluidization is proposed and constructed for investigating single metal particle’s combustion. The designed setup is able to generate a single metal particle moving upward with a well controlled velocity and trajectory and ignite it at near-uniform conditions by an infrared laser beam with flattened elliptical beam profile. Mechanically sieved narrow fractions of spherical iron particles with mean sizes in the range of around 26–54 μm were used in experiments. Particles burned in O2/N2 mixtures with oxygen content varying from 21% to 36%. Particle’s trajectories, velocities, and arbitrary radiant intensities were measured by taking images with a high-speed camera and processing them with an in-house developed data processing program. Two characteristic times associated with particle combustion were measured: 1) total duration of high-temperature phase (ttot) and 2) time to the maximum brightness (tmax). The results show that ttot and tmax can be described by a dn-law with 1.57≲n≲1.72 and 1.46≲n≲1.60, respectively. The effect of oxygen concentration on ttot,tmax, and tdec=ttot−tmax was analyzed for selected particle sizes of 30, 40, and 50 μm. It was found that tmax∝(1/XO2)n with 1.04≲n≲1.18 is almost linearly proportional to 1/XO2, while tdec shows a very weak dependency on the oxygen concentration at 26%–36%. This can be explained by the idea that the overall combustion process of iron is controlled by first external and then internal diffusion of oxygen owing to the saturation of oxygen on the particle surface.

Investigation of Glass Transition Process in Narrow Oil Fractions in a Wide Temperature Range

The results of a study of the phase behavior of six narrow oil fractions in the 150-350 K temperature range at atmospheric pressure using scanning calorimetry are presented. It is shown that there is a correlation between glass transition of the studied oil fractions and their mean boiloff temperature, molecular mass, and initial oil viscosity.

Математическое моделирование процесса гидроочистки дизельного топлива на основе кинетических характеристик его фракций

The principles of mathematical modeling of the diesel fuel hydrotreatment process as a multicomponent reaction system are considered. Feedstock containing a large number of organosulphuric components from the standpoint of increasing the level of model adequacy and calculation accuracy can be characterized by the total sulfur content in the raw material as a whole (1), the total sulfur content in pseudocomponents in the feedstock or its narrow fractions (2), the concentration of individual organosulphuric substances (3). It is shown that in cases 1 and 2, the concept of the reaction rate constant as a constant that characterizes the physico-chemical process is degenerate, and in calculations it should be considered as a kinetic characteristic that takes into account the inhomogeneity of the chemical process over time. As the hydrogenated feedstock comes into contact with the hydrogen-containing gas, the most active organosulfuric components with a high reaction rate constant are first hydrogenated on the catalyst, and at the final stage of the process, the less active components with a low reaction rate constant are hydrogenated. Examples of calculating the dependence of the kinetic characteristic and the total sulfur content in the hydrogenate in two broad fractions of diesel fuel on the time of contact of the reaction medium with the catalyst and the subsequent compounding of the fractions into diesel fuel.

Impact of dynamic sub-populations within grafted chains on the protein binding and colloidal stability of PEGylated nanoparticles.

Polyethylene glycol grafting has played a central role in preparing the surfaces of nano-probes for biological interaction, to extend blood circulation times and to modulate protein recognition and cellular uptake. However, the role of PEG graft dynamics and conformation in determining surface recognition processes is poorly understood primarily due to the absence of a microscopic picture of the surface presentation of the polymer. Here a detailed NMR analysis reveals three types of dynamic ethylene glycol units on PEG-grafted SiO2 nanoparticles (NPs) of the type commonly evaluated as long-circulating theranostic nano-probes; a narrow fraction with fast dynamics associated with the chain ends; a broadened fraction spectrally overlapped with the former arising from those parts of the chain experiencing some dynamic restriction; and a fraction too broad to be observed in the spectrum arising from units closer to the surface/graft which undergo slow motion on the NMR timescale. We demonstrate that ethylene glycol units transition between fractions as a function of temperature, core size, PEG chain length and surface coverage and demonstrate how this distribution affects colloidal stability and protein uptake. The implications of the findings for biological application of grafted nanoparticles are discussed in the context of accepted models for surface ligand conformation.

Специфика математического моделирования сложных многокомпонентных химических процессов

A critical analysis of the problem of identifying raw materials for hydrotreating diesel fuel by organosulphuric components and quantifying the value of the rate constant of the hydrodesulphurization reaction is presented. It is proposed to describe the raw material as a set of narrow fractions, in each of which the content of various organosulphuric components is considered as a single pseudo-component. The prospects of separate hydrotreatment of diesel fuel pre - fractionated into wide easily and hardly hydrogenated fractions are confirmed, which allows reducing the loading of the catalyst into the reaction unit of the plant by 1.4-1.7 times compared to the traditional process scheme.. It is proposed to use the concept of kinetic coefficient for mathematical modeling of the hydrotreating process instead of the incorrect reaction rate constant in this case. The dependence of the gross conversion rate constant of the raw material on the time of fixing the depth of its hydrodesulfurization is proved by the example of modeling the hydrotreatment of diesel fuel for a number of raw material variants.

In English

The paper presents the results of a study of the physical and chemical properties of narrow fractions of diamond nanopowders with a low content of non-diamond carbon grade ASUD-99. Six fractions with different average diameters of diamond particle aggregates from 28.785 to 3.891 μm were obtained by separating a 0.2 % aqueous suspension of the initial powders by the sedimentation method. It has been found that the smallest aggregates consist of larger particles with a smaller specific surface area and a lower interaction energy between them. This conclusion is confirmed by a decrease in the porosity of the obtained aggregates. So, if the pore volume in the largest aggregates of diamond particles is 0.859 ml/g, then in the smallest 0.550 ml/g, while the pore radius of diamond aggregates in different fractions changes insignificantly. Separation in a magnetic field at different currents of diamond nanopowders with a specific magnetic susceptibility of 0.52×10-8 m3 kg, treated with a solution of 5 % iron chloride, made it possible to obtain five fractions that differ from each other in specific magnetic susceptibility (c) – from magnetic fractions with c = 4.30×10-8 m3/kg to diamagnetic – with c = –0.11×10-8 m3/kg. It is shown that the modification of diamond nanopowders with iron ions increases the separation selectivity and makes it possible to isolate diamagnetic powders.

Continuous-Flow Flat Jet Setup for Uniform Pulsed Laser Postprocessing of Colloids.

Pulsed laser postprocessing (PLPP) of colloidal nanoparticles and related laser fragmentation in liquid (LFL) using a liquid jet setup have become an acknowledged tool to reduce the nanoparticle diameter down to a few nanometers, alter the crystal phase, or increase the defect density under high-purity and continuous-flow conditions. In recent studies on LFL that were conducted with a cylindrical liquid jet, intensity gradients and related incomplete illumination of the volume element passing through the laser beam path were reported to cause a broadening of the product particle size distribution, melting, and phase segregation. In this paper, we present a new flat jet design, which reduces the deviation of the laser intensity up to 10 times compared to the conventional cylindrical liquid jet. The experimental threshold intensity for gold nanoparticle fragmentation found with the cylindrical setup strongly deviates from the theoretical prediction, while they are in very good agreement for the flat jet setup. Additionally, a narrow product size fraction of 3 ± 2 nm was found for the flat jet, while the main product fraction gained from the cylindrical jet was 10 ± 8 nm in size under the same conditions. Consequently, the flat jet setup allows us not only to study laser fragmentation mechanisms with higher precision but also to gain product particles with narrow particle size distribution at single pulse per particle conditions even at elevated mass concentrations (>50 mg L-1). In future studies, these promising results also render the flat jet setup relevant for the other disciplines of PLPP such as laser melting and defect engineering.

DEVELOPMENT OF HEAT STORAGE MATERIALS BASED ON COMMODITY PARAFFINS

Heat storage materials on the basis of liquid paraffins and their narrow fractions with the set temperature of phase transition and the increased heat capacity for enclosing the structures of buildings are received. A method of formulating compositions heat-storage materials with melting temperatures below 250C and increased heat capacity from a mixture of narrow fractions of commodity paraffins is proposed. The technique of obtaining heat-storage materials on the basis of commodity paraffin by mixing components, in obtaining HSM with specified thermal characteristics, the research of component composition, physico-chemical and thermophysical properties, in the research of their operational properties. The technical conditions for the obtained heat- storage materials on the basis of commodity paraffins are developed and the possibility of their application in the enclosing structures of buildings is substantiated. The developed heat-storage material with the set operational properties provides energy saving due to increase of heat capacity and intensity of heat exchange of enclosing designs of buildings.

Review of Experimental Methods for Measuring the Ignition and Combustion Characteristics of Metal Nanoparticles.

Investigations in recent decades have shown that the combustion mechanism of metal particles changes dramatically with diminishing size. Consequently, theoretical description of the ignition and combustion of metal nanoparticles requires additional research. At the same time, to substantiate theoretical models, it is necessary to obtain objective experimental information about characteristics of ignition and combustion processes, which is associated with solving serious technical problems. The presented review analyzes specific features of existing experimental methods implied for studying ignition and combustion of metal nanoparticles. This particularly concerns the methods for correct determination of nanoparticles size, correct description of their heat-exchange parameters, and determining the ignition delay and combustion times. It is stressed that the problem exists of adequate comparison of the data obtained with the use of different techniques of particles’ injection into a hot gas zone and the use of different methods of reaction time measurement. Additionally, available in the literature, data are obtained for particles of different material purity and different state of oxide layer. Obviously, it is necessary to characterize in detail all relevant parameters of a particle’s material and measurement techniques. It is also necessary to continue developing advanced approaches for obtaining narrow fractions of nanoparticles and for detailed recording of dynamic particles’ behavior in a hot gas environment.

Preparation and Characteristics of Titanium Silicate Filler for Functional Materials

During the interaction of titanite with hydrochloric acid, a composite titanosilicate precipitate (TSP) of the composition TiO2 ⋅ (1.1–1.15) SiO2 ⋅ (0.8–0.85) H2O consisting of two phases is isolated—crystalline titanium dioxide of rutile modification and silica. It has been found that, during high-temperature treatment (850°C), particles of the hydrated precipitate condense with an increase in crystallinity and a decrease in Ssp almost twofold compared to freshly precipitated TSP, without sintering of particles and formation of new phases. Particles of the resulting composition are agglomerates of fragments of a fairly regular shape, which is characteristic of crystalline particles of titanium dioxide, the surface of which is coated with an amorphous silica shell. The study of the samples using an electron microscope and a laser analyzer showed that 90% of the particles are represented by a fairly narrow fraction 0.4–1 μm in size. The morphological properties of the particles of the composition, as well as its technical characteristics, including the ability to give a matte surface to transparent organic dispersions, allow one to conclude the prospects of its use as an effective filler in the manufacture of adhesives and sealants with dielectric properties and increased heat resistance. In addition, such a filler may find application in the manufacture of other functional materials.

The Influence of Selected Properties of Particles in the Jigging Process of Aggregates on an Example of Chalcedonite

The influence of the physical, geometric and chemical properties of particles on the results of aggregate separation by means of a laboratory ring jig is presented in this paper. The experiment was based on separation of chalcedonite particles in a narrow particle size fraction composed separately of regular and irregular particles, which was prepared in accordance with patent inventions. On its basis, the geometric properties—projection diameter and (volumetric and dynamic) shape coefficients—as well as physical properties—particle density—were determined in products of the regular and irregular particles. The terminal settling velocities of the regular and irregular particles were calculated for a randomly selected sample of particles in each obtained separation product. The statistical analysis of the geometric properties of the particles allowed to evaluate the influence of these parameters on aggregate processing with respect to selection of particles homogenous in terms of their shapes. The comparison of the particle shapes’ influence on the chalcedonite feed separation effects was made by the means of the values of the shape coefficients: the dynamic and volumetric ones. Additionally, tests were carried out using Raman spectroscopy in order to determine the mechanisms of density change in the aggregate. The research goal was realised through detecting and analysing the polymorphic forms of the silica and allogenic minerals precipitated on the surface and inside the chalcedonite particles.

Crush and Acid Resistance of Microsphere Narrow Fractions from Fly Ash as the Basis of Composite Materials

The crush test and acid resistance of microsphere narrow fractions with average diameter dav of 5, 8 and 25 μm of the SiO2–Al2O3–FeO system and with dav of 4 and 10 μm the CaO–SiO2–Al2O3– FeO system separated from fly ash from pulverized combustion of Ekibastuz and Irsha-Borodinsky coals were studied. It has been established that all investigated ash fractions of both raw materials are characterized by high strength: microspheres of a larger narrow fraction with dav = 25 μ m a re not destroyed by compressive loading at pressures up to 51.7 MPa, dispersed narrow fractions of microspheres with dav ≤ 10 μm – up to 68.9 MPa. Microsphere narrow fractions with aluminosilicate composition have satisfactory acid resistance; the weight loss after treatment with 15 % hydrochloric acid at 65 °C for 30 minutes was 10–15 wt. %

Successive organic solvent fractionation and structural characterization of lignin extracted from hybrid poplar by deep eutectic solvent for improving the homogeneity and isolating narrow fractions

Deep eutectic solvent (DES) treatment emerged as an efficient way to separate lignin at a moderate condition via acidolysis and hydrophobic interaction. In the attempt to realize lignin’s upgrading, this work employs successive organic solvent fractionation in DES-extracted lignin to obtain fragments with a narrow molecular weight distribution and relatively homogeneous structure. The polydispersity was decreased from 2.26 to 1.35. Purity and thermal stability were enhanced. Ethyl acetate-extracted lignin possessed the highest content of phenolic hydroxyls (3.23 mmol/g) but the lowest content of aliphatic hydroxyls of 1.10 mmol/g β-O-4 linkages were partly cleaved during DES separation and fragments containing more C–C bonds tended to be dissolved in ethyl acetate through hydrophobic interaction. The successive fractionation performed effectively in obtaining lignin fragments with diversity in main linkages and functional groups. This approach provided lignin fractions with versatility in preparation and application in thermos-plastics, lignin-derived carbon materials, antioxidants and aromatic fuels and chemicals.