Dispersed Particles Research Articles

Microstructural Characteristics and Mechanical Properties of Welded Joints and Base Material of Ultra-Supercritical Pipelines Before and After Service

This study investigated the microstructural evolution and mechanical property degradation of ultra-supercritical welded joints and base material (HR3C steel) before and after service. Mechanical property tests, including tensile and impact property tests, were conducted. The results show that the tensile strength, yield strength, elongation, and impact properties of the welded joints and base material after service were lower than those of unserviced specimens. Furthermore, optical microscopy, scanning electron microscopy, and transmission electron microscopy were used to observe the welded joint and base material specimens before and after service. In the initial state, the welded joints and base material had an austenitic microstructure and a diffusely distributed strengthening phase with the composition NbCrN. Moreover, high-temperature exposure led to precipitation processes. After service, Cr-rich M23C6 carbides with a chain-like structure precipitated near the grain boundaries of the welded joints and base material, leading to the aggregation of voids at the grain boundaries. This indicates that the coarsened M23C6 carbides at the grain boundaries negatively affect grain boundary strength, which is the main factor causing the reduction in steel plasticity and toughness. In addition, NbCrN mainly precipitated inside the grains, accompanied by dislocation pinning. The inhibitory effect of the dispersed particles on the dislocations allows the steel to maintain strength properties comparable to the initial state after service. However, the gradual deposition of NbCrN eventually degraded the strength properties.

A mathematical model of the dynamic viscosity dependence of motor oils on temperature, soot concentration, and its morphology

Objectives. A quick cold start of emergency and auxiliary power units based on diesel engines should be possible at any time without problems and in the shortest possible time. The condition of the engine oil is one of the most important factors influencing the smooth start-up of power plants. During diesel engine operation, engine oil accumulates soot in its composition, negatively affecting its rheological properties. The aim of this research is to develop a mathematical model to describe changes in the dynamic viscosity of motor oils as a function of temperature. This model will account for the concentration of soot and its morphology, based on the results of experimental studies.Methods. Standardly used motor oils for diesel engines M-14D2SE and M-5z/14D2SE were used as oil samples in the preparation of model mixtures. The dispersed phase of the suspensions comprised carbon black of the N110, N220, N330, and N220 grades, characterized by a dusty (nongranular) texture. The rheological properties of the samples were determined using a TA Instruments DHR-2 rotational rheometer. The experimental data was subjected to mathematical statistical processing, in order to obtain approximating dependencies.Results. The paper presents an analysis of the various approaches to the description of the rheology of suspensions and the results of experimental studies of the viscosity-temperature characteristics (VTCs) of model samples of oils containing soot. The extant models of the dependence of the dynamic viscosity of suspensions on temperature, volume concentration of the dispersed phase, particle size and shape are demonstrated to be inadequate for the description of the VTCs of motor oils containing soot. A model of the rheological properties of soot-oil suspensions is proposed in the form of a mathematical dependence of their dynamic viscosity on temperature, mass concentration of soot, material density and size of soot particles, characteristics of the shape and structure of primary aggregates and the ratio of the sizes of aggregates and molecules of the dispersion medium.Conclusions. It was demonstrated that a comprehensive description of the VTCs of engine oils containing soot necessitates the consideration of the structural characteristics of the primary aggregates of soot particles. A mathematical model of the VTCs of oils was developed. This model is based on the dependence of the dynamic viscosity of oils on temperature, mass concentration of soot, density of the particle material, degree of non-sphericity of aggregates, the ratio of the particle sizes of the dispersed phase (either aggregates orsingle particles of non-aggregated soot) and oil molecules, and on the structure ofsoot, characterized by adsorption of dibutyl phthalate.

Synthesis and investigation of surface morphology of dispersed polyantimonic acid particles modified with silicon dioxide

Synthesis and investigation of surface morphology of dispersed polyantimonic acid particles modified with silicon dioxide

Silicone Composites with Electrically Oriented Boron Nitride Platelets and Carbon Microfibers for Thermal Management of Electronics.

This study investigated silicone composites with distributed boron nitride platelets and carbon microfibers that are oriented electrically. The process involved homogenizing and dispersing nano/microparticles in the liquid polymer, aligning the particles with DC and AC electric fields, and curing the composite with IR radiation to trap particles within chains. This innovative concept utilized two fields to align particles, improving the even distribution of carbon microfibers among BN in the chains. Based on SEM images, the chains are uniformly distributed on the surface of the sample, fully formed and mature, but their architecture critically depends on composition. The physical and electrical characteristics of composites were extensively studied with regard to the composition and orientation of particles. The higher the concentration of BN platelets, the greater the enhancement of dielectric permittivity, but the effect decreases gradually after reaching a concentration of 15%. The impact of incorporating carbon microfibers into the dielectric permittivity of composites is clearly beneficial, especially when the BN content surpasses 12%. Thermal conductivity showed a significant improvement in all samples with aligned particles, regardless of their composition. For homogeneous materials, the thermal conductivity is significantly enhanced by the inclusion of carbon microfibers, particularly when the boron nitride content exceeds 12%. The biggest increase happened when carbon microfibers were added at a rate of 2%, while the BN content surpassed 15.5%. The thermal conductivity of composites is greatly improved by adding carbon microfibers when oriented particles are present, even at BN content over 12%. When the BN content surpasses 15.5%, the effect diminishes as the fibers within chains are only partly vertically oriented, with BN platelets prioritizing vertical alignment. The outcomes of this study showed improved results for composites with BN platelets and carbon microfibers compared to prior findings in the literature, all while utilizing a more straightforward approach for processing the polymer matrix and aligning particles. In contrast to current technologies, utilizing homologous materials with uniformly dispersed particles, the presented technology reduces ingredient consumption by 5-10 times due to the arrangement in chains, which enhances heat transfer efficiency in the desired direction. The present technology can be used in a variety of industrial settings, accommodating different ingredients and film thicknesses, and can be customized for various applications in electronics thermal management.

Investigation on the Thermal Decomposition Behavior of Molybdenum Trioxide Precursor.

The ultrafine MoO3 powders were prepared by the combination of centrifugal spray drying and calcination in this work. The thermal decomposition behavior of the spherical precursor was studied. The phase constituents, morphologies, particle size, and specific surface areas of MoO3 powders were characterized at different temperatures. It is found that the decomposition of the precursor is subjected to five stages, and forms different intermediate products, including (NH4)8Mo10O34, (NH4)2Mo3O10, (NH4)2Mo4O13, h-MoO3, and the final product α-MoO3. Moreover, the decomposition rate equation is established based on the thermal decomposition kinetic parameters of the precursor. With an increase in decomposition temperature, the morphology changes from unclear boundary particles to dispersed flake particles, and the flaky particles exhibit larger sizes, higher crystallinity, and better dispersion, which can be attributed to the mass transfer of gaseous MoO3 products. Additionally, the MoO3 particle size decreases progressively, and the specific surface area increases and then decreases. At 500 °C, it can achieve ultrafine flaky MoO3 powder with the size of thick sheets, with a thickness of about 300 nm and a length of about 1-3 μm. This research can offer an innovative strategy for preparing ultrafine MoO3 powder.

The effects of leaching and pyrolysis on particle synthesis and their impact on thermal conductivity and cooling rates of waste PCB-dispersed quenchants

Abstract This study investigates the effects of pre-treatment processes—leaching and pyrolysis—on synthesizing particle-dispersed quenchants derived from waste printed circuit boards (PCBs) for enhanced heat treatment applications. The process begins with milling PCB powder with and without pre-treatment, followed by thermal conductivity and cooling rate analysis of synthesized quenchants. Findings reveal that full pre-treated particles, which undergo leaching and pyrolysis, achieve significantly smaller sizes, up to 80.4%, compared with the half-pre-treated particles. The better improvement was due to the breakdown of epoxy resin used in the PCB. The particle size reduction enhances the quenchant's thermal conductivity up to 17.47% for the quenchant with 0.5% dispersed particle. Similarly, the maximum cooling rate was improved by 16.93% for the same quenchant. Quenching tests on S45C medium carbon steel demonstrate that particle-dispersed quenchants increase the hardness of the quenched steel, maximized at 57.8 HRC, because of the higher density of the Martensite phase developed by the higher cooling rate. This research highlights the value of pre-treatment in optimizing quenchant performance, with potential implications for improved efficiency in industrial heat treatments.

Deposition behavior of the gas-atomized 7075Al and TiB2/7075Al composite powders during cold spraying

To fabricate high-quality coatings or components of high-strength 7075Al alloy by cold spraying, it is essential to understand the impact behavior and bonding mechanisms of the feedstock powder particles. For providing a general comparison, 7075Al powder and TiB2/7075Al composite powder (7075Al alloy matrix reinforced with in-situ formed and uniformly dispersed nano-TiB2 particles) produced by gas-atomization were used as feedstocks in the present study. Single particle impact tests combined with finite element analysis (FEA) were performed on the pure Al and 7075Al-T6 substrates under different process parameter sets. To provide a more realistic description, the real powder strength and plastic parameters obtained by single-particle compression tests were used as input data in the FEA model. The results show that the presence of nano-TiB2 particles has significant strengthening effects on the composite powder, thus resulting in different plastic deformation behavior upon impact compared to 7075Al powder. When the composite particles impacted the soft material (pure Al), the substrate experienced a high degree of deformation, which led to high deposition efficiency due to the embedding effect. Comparatively, the hard substrate (7075Al-T6) was less deformed, whereas the composite particle was highly deformed. Compared to the composite particle, the 7075Al particle presented a slightly higher plastic deformation and pronounced metal jets, which led to a lower critical impact velocity for successful bonding. Interestingly, a fracture was observed at the grain boundaries of both 7075Al and TiB2/7075Al composite particles in the case of a high gas temperature regime, which probably revealed that the high shock energy associated with high-velocity impact led to such intergranular fracture.

Optimization of Black Garlic Protein Extraction Process and Exploration of Its Properties and Functions with Enzymatic Hydrolysis Products.

This study optimized the process of extracting protein from black garlic using an alkaline dissolution and acid precipitation method through response surface methodology. The optimal extraction conditions were determined as a solid-to-liquid ratio of 1:50, an extraction time of 100 min, an extraction temperature of 30 °C, and an alkaline extraction pH of 9.0. Under these optimized conditions, the actual black garlic protein (BGP) extraction yield was 12.10% ± 0.21%, and the isoelectric point of the obtained BGP was 3.1. Subsequently, this study extracted black garlic protein under optimal conditions and subjected it to enzymatic hydrolysis using different enzymes (trypsin, pepsin, and their mixed enzymes). The functional characteristics, antioxidant activity, and hypoglycemic activity of black garlic protein before and after enzymatic hydrolysis were compared. Among the hydrolysates, the pepsin hydrolysate (BGPH-P) had the smallest particle size (188.57 ± 1.93 nm) and the highest Zeta potential (-29.93 ± 0.42 mV). Scanning electron microscopy showed that BGPH-P had the smallest and most dispersed particles. Fourier-transform infrared (FTIR) spectroscopy revealed that the dual enzymatic hydrolysis hydrolysate (BGPH-PT) exhibited the most stable structure. Compared to BGP, the hydrolysates demonstrated significantly improved solubility, water-holding capacity, and foaming ability (p < 0.05), while their emulsifying activity, emulsion stability, DPPH radical scavenging capacity, and hypoglycemic activity decreased. In summary, the BGP extracted using the optimized process demonstrated good antioxidant and hypoglycemic activities, while its enzymatic hydrolysate BGPH-P exhibited excellent solubility, water-holding capacity, and emulsifying properties, providing valuable insights for the further development of black garlic protein and its hydrolysates.

Influence of Low Metal Loading on the Catalytic Activity and Stability of Supported Metal Catalysts for Methane Dry Reforming

This study aims to utilize highly active nickel catalysts supported by zirconia for the dry reforming of methane (DRM). The catalysts were prepared with a low nickel loading of 5 wt%. This study seeks to investigate how the limited nickel content (5 wt%) and various preparation methods impact the properties of the catalysts as well as their performance during the DRM reaction. To assess the physicochemical properties of the catalysts, several techniques were employed, including X-ray diffraction (XRD), N2 physisorption, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The evaluation of the activity and stability of the synthesized catalysts demonstrated that a specific configuration of the Ni/ZrO2 catalyst exhibited the best performance. The study further revealed a clear distinction between the two preparation methods. Catalysts prepared via co-precipitation displayed high activity of methane conversion (53%) and carbon dioxide conversion (55%) across all tested temperatures and maintained stability throughout the reaction. In contrast, catalysts synthesized through impregnation exhibited lower activity at all temperatures and were deactivated during the testing period. The observed catalytic activity can be attributed to a combination of factors, including highly dispersed NiO particles and a high number of oxygen vacancies within the catalyst structure. These findings underscore the critical role of catalyst preparation methods and the resulting physicochemical properties, such as phase composition and particle size, in determining catalytic performance. This highlights the potential for further enhancing the performance of these catalyst systems through optimization of preparation methods and exploration of novel support materials for the development of more efficient and sustainable DRM technologies.

Physicochemical mechanics of disperse porous materials as a new approach to assessing mechanical stability of clay soils

Data are presented on the discrepancy between theoretical calculations and experimental results on assessing the strength of fine dispersed bodies including clay soils. Physicochemical processes operating on the surface of dispersed particles are considered upon interaction of latter with water and the formation of adsorbed water films producing disjoining pressure. The presence of films exerting the disjoining effect controls the development of various types of contacts between soil particles in the course of lithogenesis, i. e., coagulational, transitional, and phase contacts. These contacts are the most important factors influencing the behavior of clay soils. The study dwells on the effect of contact types on the state, deformability and stability of clay soils under external impact. It is concluded that the assessment of clay behavior should be based on physicochemical mechanics, patterns of contact interactions in fine-grained soils, and statistical analysis of experimentally obtained parameters of the mechanical properties of clays.

Identifying the effect of sodium dodecylbenzene sulfonate surfactant and dispersed pcb-based particles as a novel heat treatment quenchant on the hardness of S45C medium carbon steel

In this study, the effect of Sodium Dodecylbenzene Sulfonate (SDBS) addition as a surfactant on the performance of the Printed Circuit Board (PCB) particle-dispersed quenchant in terms of thermal conductivity, particle stability, the microstructure and hardness of S45C medium carbon steel has been investigated. Conventional quenchants have fixed, uncontrollable cooling rates. Adding solid particles creates a thermal bridge, enabling adjustable cooling rates to address this limitation. The solid particles in the quenchant were synthesized from PCB. The surfactant helps to improve particle dispersion and avoid agglomeration by modifying the surface tension between the particles and the fluid. PCB particle-dispersed media have been prepared and used as quenchants to study the effect of PCB dispersion, and its concentrations on the heat transfer rate during quenching. Based on this research results, particle stability measurement by zeta potential shows the stability improvement up to –21.53 mV after 7wt % of surfactant addition, compared to distilled water. Due to the better particle dispersion, the thermal conductivity of the quenchant is also improved by 39 %, maximized at 0.82 W/mK when compared with the quenchant without surfactant at only 0.61 W/mK. Furthermore, the quenched steel hardness also increases by 29 %, maximized at 58 HRC at 7wt % surfactant and 0.3wt % PCB particles composition. The Dispersed PCB particles in the quenchant allow the heat flow from high to lower temperature efficiently. The experimental results show that a water-based quench medium with PCB particle dispersion is an alternative quench medium to obtain a more controlled cooling rate in steel heat treatment and is one solution for utilizing PCB electronic waste

SOLUBLE POLYMER-CURCUMIN ENCAPSULATION TO PROTECT AGAINST GAMMA IRRADIATION AND INCREASE THE WATER SOLUBILITY

Curcumin is a polyphenol derived from turmeric, a herbaceous plant native from Asia, which has been studying for medicinal properties. Over the years, different civilizations have used those plants to treat or prevent bacterial diseases. Technological advances have made it possible for scientists to study the activity mechanisms, as well as properties derived from these mechanisms, known as medicinal plants. These studies have confirmed that turmeric's medicinal properties are derived from its polyphenols, which in turn can be identified, isolated and used more efficiently. Despite curcumin's antimicrobial benefits, its highly hydrophobic molecule affects its use in biological systems, as well as its bioavailability in humans and animals. The process of modifying a molecule allows changes to be made to its characteristics, benefiting its use; in this context, encapsulation with polymers with amphiphilic characteristics, such as PVP K30, presents itself as a viable alternative for greater affinity with biosystems. The encapsulate curcumin, called C-PVP K30, proved to be possible and effective, keeping the molecule stable and in nanometric dimensions, based on results from DLS and ZETA analyses. Microscopy analysis (SEM-FEG) showed morphologically spherical and dispersed particles with small points of agglomeration. The successful encapsulation of this active substance allowed the solution to be studied under gamma radiation. The results obtained by FTIR and UV-Vis show that this process was unable to protect the curcumin molecule against ionizing radiation.

The Mechanism of Modification Influence on Non-Metallic Inclusions in the Weld Metal of High-Strength Low-Alloy Steels

An analysis of the effect of modification by dispersed particles of various compounds on the distribution, composition, and morphology of non-metallic inclusions and phase precipitates in the weld metal of low-alloy high-strength steel has been conducted. It has been established that modification with dispersed TiN or Al&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;O&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt; particles leads to the enlargement of non-metallic inclusions in the weld metal. It has been shown that some modifier particles of SiC or TiC dissolve in the liquid metal pool and precipitate as separate new phase inclusions on or near the surface of non-metallic inclusions, which overall results in changes in the composition and morphology of non-metallic inclusions in the weld metal. In the case of using ZrO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; or TiO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; modifiers, small 20-60 nm dispersed non-metallic inclusions are formed, enhancing the modification effect. During the analysis, no primary particles of modifiers were detected, but separate phase separations were detected, which may indicate the complete dissolution of particles in a liquid metal bath of some types of SiC, TiC separations and their subsequent separation from a supersaturated solid solution upon cooling welded joint. In cases where zirconium oxides ZrO2 or TiO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; were used as modifying compounds, the size reduction of refractory oxides inoculated into the welding bath to nanosize (30...70 nm, the size of which can be compared to the size of the tip of the dendrite growing from the liquid metal of the weld pool during the crystallization process, increases the efficiency of the modification.

Peculiarities of the formation of catalysts, based on γ-Al2O3 modified with Ca2+ and Ni2+ ions, highly active and resistant to carbonization in dry reforming of methane into syngas reaction: relationship between physical-chemical and catalytic properties

NixCa1-xAl2O4 samples, where x = 0.1-0.5, were obtained by co-precipitation followed by drying on air at room temperature. After calcination in air at 700 °C, an oxide compound with a defective structure g-Al2O3, in which Ni2+ and Ca2+ ions are stabilized, as well as highly dispersed fragments of NiAl2O4 and NiO was formed. After pretreatment stage (reducing in H2-containing mixture) and work in the reaction medium, nickel is partially reduced to the metallic state and leaves the structure of the compound, forming on the surface highly dispersed Ni0 particles with a size of 3–15 nm. Calcium is stabilized in the structure of g-Al2O3 and on its surface. The introduction by Ca2+ leads to a significant increase in the concentration of not very stable surface and bulk carbonates and bicarbonates, which promotes the oxidation of C-containing intermediate compounds formed on Ni0 centers. In addition, the modification of Ca2+ leads to decrease the concentration of strong acid sites on the surface, the formation of a weaker CO2 bond under reaction conditions, and the fool disappearance of signals from CO complexes with strong LAC, which significantly reduces the amount of carbon, which is formed at the stage of deposition on the surface. The resulting catalysts are characterized by high activity and stable work for a long time in the dry reforming methane reaction.

Radial evolution of interplanetary coronal mass ejection-associated particle acceleration observed by Solar Orbiter and ACE

On 2022 March 10 a coronal mass ejection erupted from the Sun, resulting in Solar Orbiter observations at 0.45 au of both dispersive solar energetic particles arriving prior to the interplanetary coronal mass ejection (ICME) and locally accelerated particles near the ICME-associated shock structure as it passed the spacecraft on 2022 March 11. This interplanetary shock was later detected on 2022 March 14 by the Advanced Composition Explorer (ACE), which was radially aligned with Solar Orbiter, at 1 au. Ion composition data from both spacecraft — via the Solar Orbiter Energetic Particle Detector/ Suprathermal Ion Spectrograph (EPD/SIS) and the Ultra Low Energy Isotope Spectrometer (ULEIS) on ACE — allowed for an in-depth analysis of the radial evolution of species-dependent ICME-driven shock-associated acceleration processes for this event. We present a study of the ion spectra observed at 0.45 and 1 au during both the gradual solar energetic particle and energetic storm particle phases of the event. The shapes of the spectra seen at each spacecraft differ significantly, likely due to the varying shock geometry: Solar Orbiter spectra tend to lack spectral breaks, and the higher-energy portions of the ACE spectra have a comparable average flux to the Solar Orbiter spectra. Through an analysis of rigidity effects on the spectral breaks observed by ACE, we conclude that the 1 au observations were largely influenced by a suprathermal pool of $ He $ ions that were enhanced due to propagation along a stream interaction region that was interacting with the ICME at the times of observation.

Effect of Dispersed ZrO2 Particles on Microstructure Evolution and Superconducting Properties of Nb-Ti Alloy.

The influence of dispersed ZrO2 particles on the microstructure evolution and the superconducting properties of a Nb-Ti alloy was investigated. The studied materials were prepared by different methods including mechanical alloying (MA) and arc-melting. The obtained samples were studied by X-ray diffraction (XRD) and vibrating-sample magnetometer (VSM). It was found that ZrO2 particles can be successively introduced into an Fe-Nb matrix by MA. However, among all prepared samples with a nominal composition of Nb-47wt%Ti-5 wt% ZrO2, only the powders, which were prepared by MA of Nb-47wt%Ti and ZrO2 powders, exhibit superconductivity with critical parameters comparable to those observed in pristine Nb-47wt%Ti alloy. In particular, the determined upper critical field at 0 K μ0Hc2(0) is close to 15.6(1) T. This value is slightly higher than 15.3(3) T obtained for Nb-47wt%Ti and it can be ascribed to the presence of introduced ZrO2 particles in the Nb-Ti matrix.

The Effect of H2O2 Pretreatment on TiO2-Supported Ruthenium Catalysts for the Gas Phase Catalytic Combustion of Dichloromethane (CH2Cl2)

In the study presented herein, a series of TiO2-supported Ru catalysts were prepared through over-impregnation with different amounts of H2O2 and applied to the catalytic combustion of dichloromethane (DCM). The experimental results show that the optimal (1 H2O2)-Ru@TiO2 catalyst sample yields 90% DCM conversion at 301 °C, which is 40 °C lower than the temperature required by the (0 H2O2)-Ru@TiO2 catalyst. This good activity is related to its high number of acid sites (especially Brønsted acid sites), an appropriate amount of uniformly dispersed RuO2 particles, and strong interaction between RuO2 and the TiO2 support. In addition, excessive H2O2 leads to the growth and phase segregation of RuO2, which weakens the interaction between RuO2 and the TiO2 support and decreases catalytic activity. Moreover, H2O2 addition also contributes to the stability of catalysts, which possibly results from the re-dispersion of RuO2 on the TiO2 support during the reaction.

Mesoporous silica-modified metal organic frameworks derived bimetallic electrocatalysts for oxygen reduction reaction in microbial fuel cells

The design of cost-effective oxygen reduction reaction (ORR) catalysts in microbial fuel cells (MFCs) remains a challenge. Herein, a mesoporous silica (mSiO2) assisted protection strategy is developed to synthesize highly dispersed CuCo nanoalloys embedded in nitrogen doped carbon Cu/Co-NC@mS catalyst using zeolitic imidazolate framework (ZIF) as carbon and nitrogen sources. The results revealed that the mSiO2 protection holds the potential to inhabit CuCo nanoalloys from aggregation and thus promotes the formation of highly dispersed small CuCo nanoparticles. The obtained catalyst with pyrolysis temperature (T) of 800 °C (Cu/Co-NC@mS-800) achieves the best ORR performance among Cu/Co-NC@mS-T catalysts, yielding a maximum power density of 1000 mW m−2 when employed as air cathode MFCs. The significantly enhanced ORR performance of Cu/Co-NC@mS-800 could be attributed to following aspects: a) highly dispersed small CuCo nanoalloy particles, improved mesoporous surface area and volume owing to mSiO2 protection; (b) the formation of concave regular dodecahedron mesoporous structure with thin graphtic carbon layer as support; (c) the synergetic effect between CuCo nanoalloys. This work provides a facile strategy for the preparation of highly dispersed bimetal nanoalloys with enhanced electrocatalytic performance for energy-related applications.

COMPLEX TECHNOLOGY OF THE CLEANING OF AGGLOMERATION GASES FROM DUST AND HARMFUL GASES WITH OBTAINING A GOOD PRODUCT

The purpose of the work is to improve the design of the dust-catching device of the sintering machine, to increase the efficiency of catching charged dust particles in laminar layers near the precipitating elements, the configuration and location of the elements of the precipitating elements, to establish the dependence of the effective (calculated) drift speed of charged dispersed particles on the speed of the medium being cleaned, with classical the process of electrogas purification and the combined flow of gases in electrofilters. It was established that the combined movement of gases in a modular unit ensures the charging of the entire population of dust particles to the limit values ​​by organizing a highly turbulent flow and keeping dust particles in the zones with the greatest tension in the corona charge covers, as well as effective trapping of charged dust particles in laminar layers near the precipitating elements . Mathematical modeling of the deposition block was carried out in order to optimize the configuration. The main dependences of the number and mutual location of precipitating elements to ensure maximum dust deposition were established. Studies of gas medium velocity spectra in models of new electrostatic precipitators have been carried out. The optimal live cross-sections of the aerodynamic partitions are determined to ensure favorable conditions for charging suspended particles and uniform distribution of the cleaned flow through the catching holes. The MV-2 modular type electric gas purification device with a capacity of 30 thousand nm3/h has been developed, based on innovative developments in the field of KEIT (combined electro-ion gas purification technology) in the field of conversion and control of cascade energy and aerodynamics of turbulent and laminar flows during inertial deposition dispersed suspension of flue gases. An apparatus for cleaning gases from a sinter machine with a capacity of up to 400,000 nm3/h is proposed. with an efficiency of 99 %, for replacing existing equipment (multicyclones). "MV-2JS" electric device was developed. This is a plasma-catalytic reactor, which allows you to produce the necessary amount of ozone in a low-cost way to oxidize the harmful components (SO2, NOx, CO) of the outgoing gases. The use of this device allows, in addition to the cleaning of flue gases from harmful gas impurities, to obtain commercial products (fertilizers, gypsum, sulfuric acid, etc.) at the output and to completely get rid of solid and liquid waste during gas desulfurization.

Cu–Zn Catalysts Derived From ZIF‐8 Applied in Ethynylation of Formaldehyde for 1,4‐Butynediol Synthesis: The Positive Effect of Carbon Layers

ABSTRACTCu‐based catalysts applied in ethynylation reaction of formaldehyde for 1,4‐butynediol synthesis has been widely concerned. The activity and stability of Cu‐based catalyst is still a challenging task in this field. Here, Cu–Zn catalysts derived from ZIF‐8 are prepared by a coprecipitation method and applied in ethynylation reaction of formaldehyde. All catalysts were characterized through thermogravimetric, x‐ray diffraction, N2 physical adsorption–desorption, transmission electron microscopy, H2‐temperture‐programmed reduction, x‐ray photoelectron spectroscopy, and Raman and Fourier transform infrared analysis. The effect of calcination temperature of ZIF‐8 on the catalyst structures and ethynylation performances are all investigated. The results show that CuO5h‐ZnO400 catalyst has the best catalytic activity, with a formaldehyde conversion of 98% and 1,4‐butynediol selectivity of 100%. It is mainly due to the presence of highly dispersed and small particle CuO. Moreover, CuO3h‐ZnO400 catalyst prepared by optimized conditions can further improve the stability in ethynylation reaction due to more carbon species on the surface of ZnO. The more carbon contents in Cu–Zn catalyst contribute to the ethynylation activity and stability due to the interaction between Cu and C species favoring Cu2C2 formed. In addition, the ethynylation reaction mechanism catalyzed by Cu–Zn catalyst is illustrated carefully. The Cu–Zn catalysts derived from ZIF‐8 can provide some ideas for the application in ethynylation reaction of formaldehyde for 1,4‐butynediol synthesis.