scholarly journals Micro-interface temperature field of catalytic particle under self-rotation regulation

2020 ◽  
Vol 194 ◽  
pp. 05002
Author(s):  
Lei Xu ◽  
Hualin Wang ◽  
Yuan Huang
Keyword(s):  
Surface Temperature ◽  
High Efficiency ◽  
Rotation Speed ◽  
Catalytic Reduction ◽  
Particle Surface ◽  
Reduction Reaction ◽  
The Self ◽  
Spherical Particles ◽  
Interface Temperature ◽  
Catalytic Particle

The micro-interface formed inside and on the surface of the catalytic particle is the place where the catalytic reaction proceeds. The micro-interface temperature is one of the important factors determining the reaction efficiency. Numerical simulation was used to investigate the fluid-solid coupled heat transfer law of micro-interface under the regulation of spherical particles’ self-rotation. The results show it takes up to 4.78 s that the average surface temperature of non-rotating particle with a diameter of 3 mm decreases from 300 ℃ to 150 ℃, which is the lowest temperature required for high-efficiency selective catalytic reduction reaction of NOx with NH3, while self-rotation can reduce the cooling rate of particles. When the direction of particle self-rotation is perpendicular to gas velocity, as the self-rotation speed increases, the high-temperature area of the particle surface diffuses more fully to the latitude direction. Significant effect can be made as the self-rotation speed reaches 5 rad/s, the uniformity of the surface temperature can be increased by 27.1 % ~ 37.7 % compared with non-rotating particle, and the uniformity can be increased by a maximum of 49.5 % at a self-rotation speed of 500 rad/s.

Facile Synthesis of Cu2O nanoparticle-loaded Carbon Nanotubes Composite Catalysts for Reduction of 4-Nitrophenol

2020 ◽  
Vol 16 (4) ◽  
pp. 617-624 ◽  
Author(s):  
Yao Feng ◽  
Ran Wang ◽  
Juanjuan Yin ◽  
Fangke Zhan ◽  
Kaiyue Chen ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Mechanical Stability ◽  
Catalytic Reduction ◽  
High Surface ◽  
High Surface Area ◽  
Reduction Reaction ◽  
Cycle Performance ◽  
Simple Method ◽  
Composite Catalysts ◽  
Cu2o Nanoparticles

Background: 4-nitrophenol (4-NP) is one of the pollutants in sewage and harmful to human health and the environment. Cu is a non-noble metal with catalytic reduction effect on nitro compounds, and.has the advantages of simple preparation, abundant reserves, and low price. Carbon nanotubes (CNT) are widely used for substrate due to their excellent mechanical stability and high surface area. In this study, a simple method to prepare CNT-Cu2O by controlling different reaction time was reported. The prepared nanocomposites were used to catalyze 4-NP. Methods: CNTs and CuCl2 solution were put into a beaker, and then ascorbic acid and NaOH were added while continuously stirring. The reaction was carried out for a sufficiently long period of time at 60°C. The prepared samples were dried in a vacuum at 50°C for 48 h after washing with ethyl alcohol and deionized water. Results: Nanostructures of these composites were characterized by scanning electron microscope and transmission electron microscopy techniques, and the results at a magnification of 200 nanometers showed that Cu2O was distributed on the surface of the CNTs. In addition, X-ray diffraction was performed to further confirm the formation of Cu2O nanoparticles. The results of ultraviolet spectrophotometry showed that the catalytic effect of the compound on 4-NP was obvious. Conclusions: CNTs acted as a huge template for loading Cu2O nanoparticles, which could improve the stability and cycle performance of Cu2O. The formation of nanoparticles was greatly affected by temperature and the appropriate concentration, showing great reducibility for the 4-NP reduction reaction.

In-situ stabilization of silver nanoparticles in polymer hydrogels for enhanced catalytic reduction of macro and micro pollutants

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Luqman Ali Shah ◽  
Rida Javed ◽  
Mohammad Siddiq ◽  
Iram BiBi ◽  
Ishrat Jamil ◽  
...  
Keyword(s):  
Catalytic Reduction ◽  
Thermo Gravimetric Analysis ◽  
Activation Parameters ◽  
Reduction Reaction ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
In Situ Stabilization ◽  
Hybrid Hydrogels ◽  
Kinetics Of

AbstractThe in-situ stabilization of Ag nanoparticles is carried out by the use of reducing agent and synthesized three different types of hydrogen (anionic, cationic, and neutral) template. The morphology, constitution and thermal stability of the synthesized pure and Ag-entrapped hybrid hydrogels were efficiently confirmed using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and thermo gravimetric analysis (TGA). The prepared hybrid hydrogels were used in the decolorization of methylene blue (MB) and azo dyes congo red (CR), methyl Orange (MO), and reduction of 4-nitrophenol (4-NP) and nitrobenzene (NB) by an electron donor NaBH4. The kinetics of the reduction reaction was also assessed to determine the activation parameters. The hybrid hydrogen catalysts were recovered by filtration and used continuously up to six times with 98% conversion of pollutants without substantial loss in catalytic activity. It was observed that these types of hydrogel systems can be used for the conversion of pollutants from waste water into useful products.

scholarly journals Quasi-graphitic carbon shell-induced Cu confinement promotes electrocatalytic CO2 reduction toward C2+ products

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ji-Yong Kim ◽  
Deokgi Hong ◽  
Jae-Chan Lee ◽  
Hyoung Gyun Kim ◽  
Sungwoo Lee ◽  
...  
Keyword(s):  
High Efficiency ◽  
Co2 Reduction ◽  
Value Added ◽  
Material Design ◽  
Catalyst System ◽  
Critical Issue ◽  
Reduction Reaction ◽  
Catalyst Design ◽  
Design Strategies ◽  
Faradaic Efficiency

AbstractFor steady electroconversion to value-added chemical products with high efficiency, electrocatalyst reconstruction during electrochemical reactions is a critical issue in catalyst design strategies. Here, we report a reconstruction-immunized catalyst system in which Cu nanoparticles are protected by a quasi-graphitic C shell. This C shell epitaxially grew on Cu with quasi-graphitic bonding via a gas–solid reaction governed by the CO (g) - CO2 (g) - C (s) equilibrium. The quasi-graphitic C shell-coated Cu was stable during the CO2 reduction reaction and provided a platform for rational material design. C2+ product selectivity could be additionally improved by doping p-block elements. These elements modulated the electronic structure of the Cu surface and its binding properties, which can affect the intermediate binding and CO dimerization barrier. B-modified Cu attained a 68.1% Faradaic efficiency for C2H4 at −0.55 V (vs RHE) and a C2H4 cathodic power conversion efficiency of 44.0%. In the case of N-modified Cu, an improved C2+ selectivity of 82.3% at a partial current density of 329.2 mA/cm2 was acquired. Quasi-graphitic C shells, which enable surface stabilization and inner element doping, can realize stable CO2-to-C2H4 conversion over 180 h and allow practical application of electrocatalysts for renewable energy conversion.

Enhancement on Stability of Nanosized Titanium Dioxide in Silicone Suspension Using Diblock Copolymer: Influence of Dispersant Structure

2013 ◽  
Vol 747 ◽  
pp. 599-602
Author(s):  
Surachet Toommee ◽  
Nisanart Traiphol
Keyword(s):  
Titanium Dioxide ◽  
Surface Area ◽  
Diblock Copolymer ◽  
High Efficiency ◽  
Particle Surface ◽  
Ethyl Acrylate ◽  
Polymer Structure ◽  
Particle Agglomeration ◽  
Nanosized Titanium Dioxide ◽  
Enhanced Adsorption

This research investigates using of poly (dimethylsiloxane-b-hydroxy ethyl acrylate) (PDMS-b-PHEA) diblock copolymer to stabilized TiO2nanoparticles in silicone fluid. The polar PHEA segment is expected to anchor on TiO2surface while the non-polar PDMS segment extends into silicone medium. To study effects of polymer structure on its stabilizing efficiency, PDMS-b-PHEA of structures 5-b-0.3, 5-b-1.1 and 8-b-1.0 are used. Results show that suspensions of particle with surface area ~40 and ~200 m2/g can be stabilized for longer than 1 and 7 hrs, respectively. The copolymer with relatively long PHEA and PDMS segments is highly effective as a dispersant. This is due to enhanced adsorption on particle surface and steric stabilization. However, in the system of 40 m2/g-TiO2, excess amounts could lead to polymer entanglement and particle agglomeration. The copolymer dispersant exhibits high efficiency for the 200 m2/g-TiO2suspension as well. In the latter system, higher concentration is required to effectively cover particle surface.

Single-step preparation of recyclable silver nanoparticle immobilized porous glass filters for the catalytic reduction of nitroarenes

RSC Advances ◽  
2015 ◽  
Vol 5 (25) ◽  
pp. 19248-19254 ◽  
Author(s):  
Hong-Ling Lin ◽  
Nga-Lai Sou ◽  
Genin Gary Huang
Keyword(s):  
Silver Nanoparticle ◽  
Porous Glass ◽  
High Efficiency ◽  
Catalytic Reduction ◽  
Single Step

A single step preparation of recyclable silver nanocatalysts for catalytic reduction of nitroarenes with high efficiency.

scholarly journals ESTABLISHING THE ROTATION SPEED VARIATION RANGE LIMITS FOR AUTO-EXCITATION OF SELF-OSCILLATING GRINDING IN A TUMBLING MILL

2020 ◽  
Vol 4 ◽  
pp. 32-35
Author(s):  
Kateryna Deineka ◽  
Yurii Naumenko
Keyword(s):  
Visual Analysis ◽  
Rotation Speed ◽  
Relative Size ◽  
Fine Fraction ◽  
Coarse Fraction ◽  
The Self ◽  
Cement Clinker ◽  
Crushed Material ◽  
Degree Of Filling ◽  
Tumbling Mill

The influence of the structure of a two-fraction polygranular feed of the chamber on the value of the drum rotation speed at auto-excitation of self-excited oscillations with a maximum swing is considered. Such a pulsating mode of movement of the charge is used in the self-oscillating process of grinding in a tumbling mill. The coarse fraction simulated the grinding bodies was steel bullets with a relative size ψdb=0.026. The fine fraction, simulated the particles of the crushed material, was a cement clinker with a relative particle size ψdm=0.00013. Variable factors of experimental studies were: the degree of filling the chamber in the state of rest κbr=0.25; 0.29; 0.33 and the degree of filling the gaps between the particles of the coarse fraction with particles of the fine fraction κmbgr=0.0625; 0.375; 0.6875; 1. The method of visual analysis of transient processes of self-oscillating modes of feed behavior in the cross section of the rotating drum chamber is applied. Measurements of the speed limits of the drum rotation were carried out with auto-excitation of self-oscillations of the filling. The magnitude of the self-oscillation swing was estimated by the increase in the difference between the maximum and minimum values of the filling dilatancy for one period of pulsations. An increase in the upper limit of the speed range ψω2 with a decrease in κbr and κmbgr was established. The growth rate of ψω2 increases at low values of κbr and κmbgr. Some increase in the lower limit of the ψω1 range with a decrease in κbr and κmbgr was revealed. An increase in the range of speeds of rotation was recorded at the maximum range of self-oscillations ψω1–ψω2 with a decrease in the connected interaction of the intra-mill filling. This coherent interaction is due to an increase in κbr and κmbgr. The value of the ψω1–ψω2 range varies from 1.01–1.03 at κbr=0.33 and κmbg=1 to 1.22–1.66 at κbr=0.25 and κmbgr=0.0625. The range gets its maximum value with fine and superfine grinding

scholarly journals A low-temperature hydrothermal synthesis of submicron spherical BaF2

RSC Advances ◽  
2021 ◽  
Vol 11 (63) ◽  
pp. 40051-40058
Author(s):  
Xiao Li ◽  
Yuxiang Zhao ◽  
Bo Li ◽  
Shuxuan Wang ◽  
Xingwu Zou
Keyword(s):  
Hydrothermal Synthesis ◽  
Low Temperature ◽  
Hydrothermal Method ◽  
Self Assembly ◽  
The Self ◽  
Spherical Particles

BaF2 submicron spherical particles, formed by the self-assembly of nanocubes, were prepared by a low-temperature hydrothermal method with the aid of EDTA-2Na.

scholarly journals Morphology and Release Kinetics of Protein-Loaded Porous Poly(L-Lactic Acid) Spheres Prepared by Freeze-Drying Technique

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Takashi Sasaki ◽  
Kazuki Tanaka ◽  
Daisuke Morino ◽  
Kensuke Sakurai
Keyword(s):  
Lactic Acid ◽  
Freeze Drying ◽  
Release Kinetics ◽  
Particle Surface ◽  
Spherical Particles ◽  
Freeze Dried ◽  
Model Drug ◽  
Drug Compound ◽  
Kinetics Of ◽  
Step Mechanism

Freeze-drying a biodegradable polymer, poly(L-lactic acid) (PLLA), from 1,4-dioxane solutions provided very porous spherical particles of ca. 3 mm in radius with specific surface area of 8–13 m2 g−1. The surface of the particle was found to be less porous compared with its interior. To apply the freeze-dried PLLA (FDPLLA) to drug delivery system, its morphology and drug releasing kinetics were investigated, bovine serum albumin (BSA) being used as a model drug compound. Immersion of FDPLLA into a BSA aqueous solution gave BSA-loaded FDPLLA, where mass fraction of the adsorbed BSA reached up to 79%. Time-dependent release profile of BSA in water suggested a two-step mechanism: (1) very rapid release of BSA deposited on and near the particle surface, which results in an initial burst, and (2) leaching of BSA from the interior of the particle by the diffusion process. It was suggested that the latter process is largely governed by the surface porosity. The porosity of both the interior and surface was found to decrease remarkably as the concentration of the original PLLA/1,4-dioxane solution increases, C0. Thus, C0 is a key parameter that controls the loading and releasing of BSA.

Promoting interfacial charge transfer by B/N co-doping enable efficient ORR catalysis of carbon encapsulated Fe2N

2022 ◽  
Author(s):  
Zhi Xie ◽  
Qiaoling Li ◽  
Xingkai Peng ◽  
Xuewei Wang ◽  
Lingli Guo ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Porous Carbon ◽  
High Efficiency ◽  
Reduction Reaction ◽  
Carbon Shell ◽  
Co Doping ◽  
Interfacial Charge ◽  
Electrochemical Catalysts

High efficiency and durability are two key targets for developing electrochemical catalysts for oxygen reduction reaction (ORR). Here, B/N co-doping porous carbon shell encapsulated Fe2N nanoparticles (NPs) was synthesized as...

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