Literatura científica selecionada sobre o tema "Continuous powder synthesis reactor"
Crie uma referência precisa em APA, MLA, Chicago, Harvard, e outros estilos
Consulte a lista de atuais artigos, livros, teses, anais de congressos e outras fontes científicas relevantes para o tema "Continuous powder synthesis reactor".
Ao lado de cada fonte na lista de referências, há um botão "Adicionar à bibliografia". Clique e geraremos automaticamente a citação bibliográfica do trabalho escolhido no estilo de citação de que você precisa: APA, MLA, Harvard, Chicago, Vancouver, etc.
Você também pode baixar o texto completo da publicação científica em formato .pdf e ler o resumo do trabalho online se estiver presente nos metadados.
Artigos de revistas sobre o assunto "Continuous powder synthesis reactor"
1
Cho, Young-Sang, Chiyeop Hwang, Seong-Jun Kim e U.-Hyeon Park. "Continuous Synthesis of Monodisperse Spherical Silica Powder Using Tubular Reaction System". Korean Journal of Metals and Materials 60, n.º 6 (5 de junho de 2022): 409–22. http://dx.doi.org/10.3365/kjmm.2022.60.6.409.
Texto completo da fonteResumo:
In the present study, monodisperse silica nanospheres were synthesized using a tubular reaction system in a continuous way. Screw-type blades were inserted inside a T-mixer for static mixing of the reactant streams which consisted of TEOS and NH4OH/H2O diluted with ethanol, for the continuous synthesis of the silica suspension. The diameter of the silica powder was monitored as a function of production time using dynamic light scattering to determine the optimum retention time and tube length, which were found to be 125 minutes and 7.5 m, respectively. The effects of reactant compositions on particle size were investigated by adjusting the amount of ammonia and water in the sol-gel reaction, which were then compared with the results from a batch reactor. Both the particle size and polydispersity index (PDI) of the silica suspension were measured to be comparable to nanospheres synthesized using a batch reactor. This implies that the tubular reaction system is more beneficial for potential industrial production applications in the size range from 115 to 310 nm, due to its continuous powder synthesis. The effect of the reaction medium was also studied, by replacing ethanol with methanol or propanol, indicating that the deviation in particle size with production time was not a serious issue in alcohols with lower molecular weight, such as methanol and ethanol.
2
Kammler, Hendrik K., e Sotiris E. Pratsinis. "Carbon-coated titania nanostructured particles: Continuous, one-step flame-synthesis". Journal of Materials Research 18, n.º 11 (novembro de 2003): 2670–76. http://dx.doi.org/10.1557/jmr.2003.0373.
Texto completo da fonteResumo:
Concurrent synthesis of titania-carbon nanoparticles (up to 52 wt.% in C) was studied in a diffusion flame aerosol reactor by combustion of titanium tetraisopropoxide and acetylene. These graphitically layered carbon-coated titania particles were characterized by high-resolution transmission electron microscopy (HRTEM), with elemental mapping of C and Ti, x-ray diffraction (XRD), and nitrogen adsorption [Brunauer-Emmett-Teller (BET)]. The specific surface area of the powder was controlled by the acetylene flow rate from 29 to 62 m2/g as the rutile content decreased from 68 to 17 wt.%. Light blue titania suboxides formed at low acetylene flow rates. The average XRD crystal size of TiO2 decreased steadily with increasing carbon content of the composite powders, while the average BET primary particle size calculated from nitrogen adsorption decreased first and then approached a constant value. The latter is attributed to the formation of individual carbon particles next to carbon-coated titania particles as observed by HRTEM and electron spectroscopic imaging.
3
Courtecuisse, V. Gourincha, J. F. Bocquet, K. Chhor e C. Pommier. "Modeling of a continuous reactor for TiO2 powder synthesis in a supercritical fluid — experimental validation". Journal of Supercritical Fluids 9, n.º 4 (dezembro de 1996): 222–26. http://dx.doi.org/10.1016/s0896-8446(96)90052-2.
Texto completo da fonte
4
Medesi, Anna Julia, Dorit Nötzel e Thomas Hanemann. "PVB/PEG-Based Feedstocks for Injection Molding of Alumina Microreactor Components". Materials 12, n.º 8 (14 de abril de 2019): 1219. http://dx.doi.org/10.3390/ma12081219.
Texto completo da fonteResumo:
The ceramic injection molding (CIM) process is a cost-effective powder-based near net shape manufacturing process for large-scale production of complex-shaped ceramic functional components. This paper presents the rheological analysis of environmentally friendly CIM feedstock formulations based on the binder components polyvinyl butyral (PVB) and polyethylene gycol (PEG). The prepared PVB/PEG-based alumina molding compounds were investigated with respect to their PVB:PEG ratios as well as to their powder filling degrees in the range between 50 and 64 vol.%. Corresponding viscosities and shear stresses were determined for increasing shear rates to show the effects of increased PEG content and solid loadings on them. Two single reactor components were injection molded and subsequently joined in their green state for fabrication of an alumina microreactor. The intended purpose of the alumina microreactors is their potential application as wear-resistant and hydrothermal stable multifunctional devices (µ-mixer, µ-reactor, µ-analyzer) for continuous hydrothermal synthesis (CHTS) of metal oxide nanoparticles in supercritical water (sc-H2O) as the reaction medium.
5
Zeng, Ling Ke, Yan Chun Liu, Wen Cheng Zhu, Ping An Liu, Hui Wang, Xiao Su Cheng e Qian Ying Liang. "Investigation on the Continuous Microwave Synthesis of Nano Titanium Carbide Powder". Advanced Materials Research 1064 (dezembro de 2014): 66–70. http://dx.doi.org/10.4028/www.scientific.net/amr.1064.66.
Texto completo da fonteResumo:
In this paper, the reaction mechanism of inorganic carbon and titanium dioxide synthesis of titanium carbide thermodynamic were explored, and a thermodynamic basis date for the microwave heating was provided. Through analyzing the experimental results for the thermal stability of titanium carbide, we could obtain the theoretical parameters for the actual synthesis process.
6
Azami, Mahmoud, Sasan Jalilifiroozinezhad e Masoud Mozafari. "Calcium Fluoride/Hydroxyfluorapatite Nanocrystals as Novel Biphasic Solid Solution for Tooth Tissue Engineering and Regenerative Dentistry". Key Engineering Materials 493-494 (outubro de 2011): 626–31. http://dx.doi.org/10.4028/www.scientific.net/kem.493-494.626.
Texto completo da fonteResumo:
In this research, a novel biphasic solid solution consisted of Calcium fluoride (CF) and fluorinated-hydroxyapatite (FHAp) was successfully synthesized through a modified precipitation method using buffer solution. The obtained results confirmed the formation of biphasic nanocrystalline powder composed of about 46% CF and 54% (w/w%) FHAp. This product can be considered as an osteoconductive dental filler or implant with the ability of dental carries prevention due to release of fluorine ions. Herein, the usage of buffer solution for this purpose not only can produces biphasic powder but also provides the possibility of establishment of a continuous synthesis method without manual interfere for adjusting pH of the reactor.
7
Petrov, Stanislav, Serhii Bondarenko e Koichi Sato. "Consideration of the possibility of large-scale plasma-chemical production of nanosilicon for lithium-ion batteries". Technology audit and production reserves 3, n.º 3(65) (27 de junho de 2022): 6–14. http://dx.doi.org/10.15587/2706-5448.2022.259066.
Texto completo da fonteResumo:
The object of research is the process of obtaining silicon nanomaterials for lithium-ion batteries of energy storage devices, and the subject of research is the technology of gas-phase plasma-chemical synthesis for the production of Si-nanoparticles. In the course of the study, numerical simulation methods were used, which made it possible to determine the parameters of temperature fields, velocities and concentrations. To study the processes of synthesis of nanopowders, a plasma reactor with an electric arc plasma torch of a linear scheme and using an argon-hydrogen mixture as a plasma-forming gas was developed. To analyze the influence of an external magnetic field on the control of the plasma jet parameters, a series of experiments was carried out using an electric arc plasma torch on plasma laboratory facilities with a power of 30 and 150 kW. The influence of a magnetic field on the process of formation and evaporation of a gas-powder flow in a plasma jet was studied by determining the configuration, geometric dimensions, and structure of the initial section of the jet. In this case, the dispersed material – silicon powder was fed to the plasma torch nozzle section according to the radial scheme. Experimental confirmation of the phenomenon of elongation of the high-temperature initial section of the plasma jet in a longitudinal magnetic field has been obtained. The experimental results indicate that the creation of a peripheral gas curtain significantly changes the characteristics of heat and mass transfer in the reactor. It should be expected that for optimization it is possible to exclude the deposition of nanosilicon particles on the walls of the reactor and provide conditions for continuous operation. The effect of two-phase flow, heat transfer, and mass flow of nanoparticles, including the surface of a plasma reactor with limited jet flow, in the processes of obtaining silicon nanopowders has been studied. This made it possible to correct a number of technological characteristics of the process of constructive design of the actions of plasma synthesis of nanopowders. The patterns obtained can be used for constructive and technological design in the creation and development of a pilot plant for high-performance production of nanosilicon powders.
8
Li, Mi, Xiao Wu, Dongxue Han, Renyu Peng, Yong Yang, Li Wu e Wencong Zhang. "A High-Efficiency Single-Mode Traveling Wave Reactor for Continuous Flow Processing". Processes 10, n.º 7 (24 de junho de 2022): 1261. http://dx.doi.org/10.3390/pr10071261.
Texto completo da fonteResumo:
This paper proposes a high-efficiency single-mode traveling wave reactor based on a rectangular waveguide and its design method for continuous flow processing. The reactor has a large-capacity reaction chamber (1000 mm × 742.8 mm × 120 mm) that can provide high-energy-efficiency and approximately uniform microwave heating. The microwave heating uniformity is improved by maintaining single-mode microwave transmission and eliminating higher-order modes in such a multi-mode reaction chamber. The high energy efficiency of microwave heating is achieved by adopting impedance matching techniques. The incident microwave in the reactor can remain in a traveling wave state, and the power reflection can be minimized. Several numerical simulations based on multi-physics modeling are conducted to investigate the heating uniformity, the energy efficiency and the flexibility under different operation conditions. The results show the microwave energy efficiency can be higher than 99%, and meanwhile, the coefficient of temperature variation can be lower than 0.4. Furthermore, when the reactor is operated under different flow velocities and with different heating materials, both the energy efficiency and the heating uniformity can also meet the above requirements. The proposed reactor can be used in the applications such as oil processing, wastewater tackling, chemical synthesis, beverage sterilization and other microwave-assisted continuous flow processes that require high heating uniformity, high energy efficiency and good adaptability.
9
Lübke, Mechthild, Juhun Shin, Peter Marchand, Dan Brett, Paul Shearing, Zhaolin Liu e Jawwad A. Darr. "Highly pseudocapacitive Nb-doped TiO2 high power anodes for lithium-ion batteries". Journal of Materials Chemistry A 3, n.º 45 (2015): 22908–14. http://dx.doi.org/10.1039/c5ta07554h.
Texto completo da fonte
10
Yan, Xiaojie, William Trevillyan, Ioannina Castano, Yugang Sun, Ralph Muehleisen e Jie Li. "Continuous-Flow Synthesis of Thermochromic M-Phase VO2 Particles via Rapid One-Step Hydrothermal Reaction: Effect of Mixers". Journal of Nanomaterials 2019 (10 de junho de 2019): 1–10. http://dx.doi.org/10.1155/2019/2570698.
Texto completo da fonteResumo:
VO2 particles are promising materials for thermochromic smart windows that reduce building energy loss. Continuous-flow hydrothermal processes showcase advantages for synthesizing VO2 particles compared with traditional batch reaction systems. Mixers play a crucial role in particle fabrication in continuous-flow systems. In this study, a Center T-Mixer and a Collision Cross-Mixer are developed and implemented in a hot water fluidized suspension reaction (HWFSR) system. The influence of the resident time on the particle phase and size was evaluated, and properties of particles derived from systems equipped with differing mixers were compared. The resulting particles were characterized using techniques of X-ray powder diffraction (XRD) analysis, scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). When compared with the Center T-Mixer, results indicate that the Collision Cross-Mixer has better control regarding the morphology and size distribution of resulting particles while improving the transition temperatures of the as-synthesized materials. HWFSR systems containing novel mixer designs are capable of producing pure M-phase VO2 particles in a single step contrary to the current reactor design that use a second postheat treatment step, and they are capable of synthesizing many other nanoparticle species, especially those requiring high temperature and pressure reaction conditions.
Teses / dissertações sobre o assunto "Continuous powder synthesis reactor"
1
Delaunay, Florian. "Élaboration de céramiques transparentes d’oxydes de terres rares pour l’optique : Étude de nouveaux additifs de frittage à base de fluor et synthèse de nanopoudres par réacteur continu". Electronic Thesis or Diss., Limoges, 2024. http://www.theses.fr/2024LIMO0102.
Texto completo da fonteResumo:
Ces travaux de thèse portent sur l’élaboration de céramiques transparentes pour des applications lasers comme milieu amplificateur, absorbant saturable ou scintillateur. Les composés étudiés sont les grenats et sesquioxydes de terres rares qui présentent d’excellentes propriétés thermomécaniques. Dans un premier chapitre, l’impact du fluor et de ses dérivés sur les mécanismes de frittage naturel de sesquioxydes de terres rares (Y2O3, Lu2O3) a été étudié. Au final, des céramiques transparentes de Y2O3 et Lu2O3 dopées à l’holmium ont été élaborées par frittage sous charge et leurs propriétés spectroscopiques étudiées. Dans un second chapitre, des nanopoudres de YAG ont été élaborées par la voie chimique de coprécipitation. Une étude des paramètres de synthèse a été menée afin de déterminer les meilleures conditions dans le but de synthétiser des poudres de YAG pures, fines et homogènes à l’aide d’un réacteur batch. Par la suite, ce procédé de synthèse a été transposé à l’utilisation d’un réacteur continu de type piston. L’influence du type de réacteur sur la pureté et la morphologie des nanopoudres de YAG synthétisées a été étudiée. Enfin, l’étude du comportement au frittage des nanopoudres ainsi obtenues a permis l’obtention de céramiques transparentes de YAGThis thesis focuses on the development of transparent ceramics for laser applications as laser amplifiers, saturable absorbers or scintillators. The compounds studied are rare earth garnets and sesquioxides, which have excellent thermomechanical properties. In a first chapter, the impact of fluorine and its derivatives on the natural sintering mechanisms of rare earth sesquioxides (Y2O3, Lu2O3) was studied. Ultimately, transparent ceramics of Y2O3 and Lu2O3 doped with holmium were produced by pressure sintering and their spectroscopic properties studied. In a second chapter, YAG nanopowders were produced by the chemical coprecipitation route. A study of the synthesis parameters was carried out in order to determine the best conditions in order to synthesize pure, fine and homogeneous YAG powders using a batch reactor. Subsequently, this synthesis process was transposed to the use of a continuous piston-type reactor. The influence of the reactor type on the purity and morphology of the synthesized YAG nanopowders was studied. Finally, the study of the sintering behavior of the nanopowders thus obtained made it possible to obtain transparent YAG ceramics
2
Azeez, Qaisar A. "Synthesis of ultrafine aluminum nitride powders in a flow reactor". Ohio : Ohio University, 1988. http://www.ohiolink.edu/etd/view.cgi?ohiou1182779122.
Texto completo da fonte
3
Hook, Benjamin D. A. "The development of a continuous-flow photochemical reactor and its application to the synthesis of stemoamide". Thesis, University of Bristol, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.441339.
Texto completo da fonte
4
Strandberg, Martin. "From torrefaction to gasification : Pilot scale studies for upgrading of biomass". Doctoral thesis, Umeå universitet, Institutionen för tillämpad fysik och elektronik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-103046.
Texto completo da fonteResumo:
Increasing the share of biomass, preferably by replacing fossil fuels, is one way to mitigate the present climate change. Fossil coal can be directly replaced by co-combustion of coal and biomass and fossil engine fuels (gasoline and diesel) could potentially partly be replaced by synthetic renewable fuels produced via entrained flow gasification of biomass. The use of biomass in these processes is so far limited, partly because of the fibrous and hygroscopic nature of biomass which leads to problem in storing, transportation, handling and feeding. This thesis demonstrates how the challenging characteristics of raw biomass are mitigated by the pretreatment method torrefaction. Torrefaction is a process where biomass is heated in an oxygen deficient atmosphere to typically between 240 and 350°C for a time period of 2 minutes to 1 hour. Most of the torrefaction R&D in the literature have so far been performed with bench-scale batch reactors. For the purpose of carefully studying continuous torrefaction, a 20 kg/h torrefaction pilot plant was therefore designed, constructed and evaluated. The overall conclusion from this thesis is that the many benefits of torrefied biomass are valid also when produced with a continuous pilot plant and for typically Swedish forest biomasses. Some of the documented improved biomass properties are increased heating value, increased energy density, higher friability (lower milling energy) and less hydrophilic biomass (less moisture uptake). Most of the improvements can be attributed to the decomposition of hemicellulose and cellulose during torrefaction. The most common variables for describing the torrefaction degree are mass yield or anhydrous weight loss but both are challenging to determine for continuous processes. We therefore evaluated three different methods (one existing and two new suggestions) to determine degree of torrefaction that not require measurement of mass loss. The degree of torrefaction based on analyzed higher heating value of the raw and torrefied biomass (DTFHHV) predicted mass yield most accurate and had lowest combined uncertainty. Pelletizing biomass enhance transportation and handling but results from pelletization of torrefied biomass is still very limited in the literature and mainly reported from single pellet presses. A pelletization study of torrefied spruce with a ring die in pilot scale was therefore performed. The bulk energy density was found to be 14.6 GJ/m3 for pelletized torrefied spruce (mass yield 75%), a 40% increase compared to regular white pellets and therefore are torrefied pellets more favorable for long distance transports. More optimization of the torrefied biomass and the pelletization process is though needed for acquiring industrial quality pellets with lower amount of fines and higher pellet durability than attained in the present study. Powders from milled raw biomass are generally problematic for feeding and handling and torrefied biomass has been proposed to mitigate these issues. The influence of torrefaction and pelletization on powder and particle properties after milling was therefore studied. The results show that powder from torrefied biomass were enhanced with higher bulk densities, lower angle of repose as well as smaller less elongated particles with less surface roughness. Even higher powder qualities were achieved by pelletizing the torrefied biomass before milling, i.e. another reason for commercial torrefied biomass to be pelletized. Entrained flow gasification (EFG) is a promising option for conversion of biomass to other more convenient renewable energy carriers such as electricity, liquid biofuels and green petrochemicals. Also for EFGs are torrefied fuels very limited studied. Raw and torrefied logging residues were successfully gasified in a pilot scale pressurized entrained flow biomass gasifier at 2 bar(a) with a fuel feed corresponding to 270 kWth. Significantly lower methane content (50% decrease) in the syngas was also demonstrated for the torrefied fuel with mass yield 49%. The low milling energy consumption for the torrefied fuels compared to the raw fuel was beneficial for the gasification plant efficiency.
5
Sauks, Jennifer. "A Continuous Flow Microwave Reactor for Organic Synthesis". Thesis, 2012. http://hdl.handle.net/1807/42898.
Texto completo da fonteResumo:
Microwave reactors are important tools in chemical synthesis, as they can lead to unprecedented reductions in reaction times and improved reaction yields. In order to scale-up the technology for greater throughput and industrial application, reactor types are moving from batch to continuous flow reactors. This research designed, built, verified and modeled a continuous flow microwave reactor. The reactor could operate under high temperature/high pressure conditions, and was connected to in-line gas chromatography/mass spectrometry, for real time sample analysis.
Specifically, a pressure device was developed to enable the reactor to run under high pressure conditions (< 1100 psi) without the use of a conventional back-pressure device. The reactor design was verified using two chemical reactions, and an in-line analytic apparatus was developed to assess the potential for reactor operation with in-line GC/MS. Additionally, a computational fluid dynamic model was developed to better understand the heat and mass transfer inside the reactor.
6
Wang, Yao-Hsuan, e 王耀萱. "Scale up of a Spinning Disk Reactor for Preparing Fine Powder in a Continuous Mode". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/71780929482598386760.
Texto completo da fonteResumo:
博士國立臺灣大學
化學工程學研究所
99
Nano/micro particles, which have excellent physical and chemical properties, can widely applied to various industries, such as biological, electrical, and chemical, due to their small size and imperfect surface structure, which are different from that of bulk materials. The common methods for preparing particles include milling and precipitation. For the traditional milling method, the products are usually contaminated or the crystal lattice of products is disrupted. The precipitation method is most popular in industry for its simplicity, low cost, and ease of manipulation. But the reactive precipitation method using a batch stirred vessel is hard to improve the product quality and production capacity. The particle size and shape are difficult to control because of the poor mixing efficiency. To overcome these problems, an efficient method of rotation packed bed, which is one of the high-gravity equipment, has been applied by Chen et al. (2000) to synthesize CaCO3 nanoparticles in a recycle mode. The reaction time in a rotating packed bed is around 5- 15 min for 1 L reactant aqueous solution. At the same operating conditions, the reaction time in a conventional stirred reactor is eight times as large as that in a rotating packed bed. It is apparent that recycle operation in a high-gravity reactor has shortened the reaction time. If the recycle operation is replaced by the continuous operation, the production rate will be enhanced. There are two types of high-gravity equipment, i.e. rotation packed bed and spinning disk. The latter is better for preparing particles due to less chance of particle collision to form agglomerates. In our laboratory, several compounds have been successfully synthesized using the SDR in a continuous mode, such as CaCO3, Mg(OH)2, Ag , AgI, and SMZ (drug). In the silver particle preparation, AgNO3 and PVP (protecting agent) were dissolved in an aqueous solution, and then the solution was mixed with an aqueous solution of glucose and NaOH to produce Ag particles through a reducing reaction. In the drug precipitation reaction, the drug and protecting agent were first dissolved in an alkaline solution, and an acidic solution was added and mixed to change the solubility of solution, and then drug particles were recrystallized. However, the scale up of the SDR for preparing organic and inorganic particles in a continuous mode has not been discussed and compared. In this study, the disk diameter was scaled up to 50cm to increase the retention time and to improve the yield of silver product. In the drug particle preparation, drugs were recrystallized with the larger SDR fitted with circular tube liquid distributors to obtain smaller particles. Drugs of p-aminosalicylic acid (PAS) and glilbenclamide (GBM) were chosen in this study of continuous operation. The main theme of this research was to discuss various operation conditions on particle size and yield, and to compare the performance of organic and inorganic systems. The equipment consists of a spinning disk of diameter being 12.0cm, 19.5cm, and 50.0cm, fitted with liquid distributors of straight or circular tubes. In the process for preparing silver nanoparticles under the appropriate operating conditions, the effects of the disk size and liquid distributors were not observed on the silver particle size with the size, which was around 10nm. In addition, when the reactant flow rate varied from 0.3 to 5.0 L/min, the particle size remained quite constant. In the process for preparing drug particles, when increasing spinning disk diameter and using circular liquid distributors, the drug particles size could be reduced to micro or submicron level. On the other hand, the particle size of drug increased with increasing reactant flow rate due to the poor mixing efficiency. Therefore, the suitable reactant flow rate was between 0.25 L/min and 0.50 L/min. The size and crystalline intensity of the recrystallized drug were lower compared to that of the commercial drug, and thus the dissolution rate was enhanced. The silver particles synthetized by the chemical reaction method were smaller than 10nm and the production rate was 31kg with the yield of 40.1%. The PAS drug particles prepared by the neutralization method were reduced to submicron level and the production rate was 23kg with the yield of 54.0%. The GBM drug particles prepared by the neutralization method were around 1μm and the production rate was 1.8kg with the yield of 92.6%.
7
El-Ballouli, Ala’a O. "Continuous-Flow Synthesis and Materials Interface Engineering of Lead Sulfide Quantum Dots for Photovoltaic Applications". Diss., 2016. http://hdl.handle.net/10754/611210.
Texto completo da fonteResumo:
Harnessing the Sun’s energy via the conversion of solar photons to electricity has emerged as a sustainable energy source to fulfill our future demands. In this regard, solution-processable, size-tunable PbS quantum dots (QDs) have been identified as a promising active materials for photovoltaics (PVs). Yet, there are still serious challenges that hinder the full exploitation of QD materials in PVs. This dissertation addresses two main challenges to aid these QDs in fulfilling their tremendous potential in PV applications.
First, it is essential to establish a large-scale synthetic technique which maintains control over the reaction parameters to yield QDs with well-defined shape, size, and composition. Rigorous protocols for cost-effective production on a scale are still missing from literature. Particularly, previous reports of record-performance QD-PVs have been based on small-scale, manual, batch syntheses. One way to achieve a controlled large-scale synthesis is by reducing the reaction volume to ensure uniformity. Accordingly, we design a droplet-based continuous-flow synthesis of PbS QDs. Only upon separating the nucleation and growth phases, via a dual-temperature-stage reactor, it was possible to achieve high-quality QDs with high photoluminescence quantum yield (50%) in large-scale. The performance of these QDs in a PV device was comparable to batch-synthesized QDs, thus providing a promise in utilizing automated synthesis of QDs for PV applications.
Second, it is crucial to study and control the charge transfer (CT) dynamics at QD interfaces in order to optimize their PV performance. Yet, the CT investigations based on PbS QDs are limited in literature. Here, we investigate the CT and charge separation (CS) at size-tunable PbS QDs and organic acceptor interfaces using a combination of femtosecond broadband transient spectroscopic techniques and steady-state measurements. The results reveal that the energy band alignment, tuned by the quantum confinement, is a key element for efficient CT and CS processes. Additionally, the presence of interfacial electrostatic interaction between the QDs and the acceptors facilitates CT from large PbS QD (bandgap < 1 eV); thus enabling light-harvesting from the broad near-infrared solar spectrum range.
The advances in this work – from automated synthesis to charge transfer studies – pave new pathways towards energy harvesting from solution-processed nanomaterials.
8
Peng, Guan-Yi, e 彭冠益. "Synthesis of o-Hydroxybenzoic Acid Butyl Ester in Continuous Flow Reactor via Ultrasound Assisted Tri-Liquid Phase-Transfer Catalysis". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/71619642902832679634.
Texto completo da fonteResumo:
碩士國立中興大學
化學工程學系所
96
The present study is to investigate the kinetics of synthesizing o-hydroxybenzoic acid n-butyl ester in a continuous flow reactor via ultrasound-assisted tri-liquid phase-transfer catalysis. The operating parameters including agitation speeds, types of catalyst, amount of catalyst, types of solvent, reaction temperature, types of inorganic salt, amount of reactant, space time, ultrasonic frequency and power, were all performed to find the optimal reaction conditions. Sonochemistry is a technique to increase chemical reaction rate by ultrasounic irradiation. Ultrasound assisted effect can energize to promote the chemical reaction. The reactor was designed by keeping the third-liquid phase in middle part of the reactor, and both of the aqueous phase and organic phase flowing through the third-liquid phase for reaction. The yield of o-hydroxybenzoic acid n-butyl ester increases with the space time, so the flow rates of aqueous phase and organic phase were both controlled at 0.3 ml/min. Increasing the organic reactant concentration butylbromide can increae the reaction activity. The lower ultrasonic frequency makes the yield of product higher. Mass transfer resistance can be neglected by agitation speed more than 150 rpm. The mechanism and kinetics in a continuous-flow reaction were proposed, and we can calculate the kapp by the model. For high product yield and cost effective, the system condition of agitation speed at 150 rpm, catalyst tetrabutylphosphonium bromide (TBPB) at 0.0125 mol, ultrasonic frequency at 28 kHz and power 300 W, the reaction temperature at 70 ℃, the product in the organic phase was 78.8 %. The apparent activation energy can be obtained as 14.5 kcal/mol in the range of 50~80 ℃. Combining agitation and ultrasound irradiation makes the reaction activity advance a lot. The yield of product was 49.7 % without any agitation and ultrasound assisted. Under the agitation, the yield of product was 65.1% without any ultrasound assisted. The yield of product raised to 58.2 % with ultrasound promoting the reaction. Using agitation and ultrasound at the same time, the product yield was obtained 78.2 %, raising the product yield by 57.3% higher than that without any assistance of agitation and ultrasound.
Livros sobre o assunto "Continuous powder synthesis reactor"
1
Floudas, Christodoulos A. Nonlinear and Mixed-Integer Optimization. Oxford University Press, 1995. http://dx.doi.org/10.1093/oso/9780195100563.001.0001.
Texto completo da fonteResumo:
Filling a void in chemical engineering and optimization literature, this book presents the theory and methods for nonlinear and mixed-integer optimization, and their applications in the important area of process synthesis. Other topics include modeling issues in process synthesis, and optimization-based approaches in the synthesis of heat recovery systems, distillation-based systems, and reactor-based systems. The basics of convex analysis and nonlinear optimization are also covered and the elementary concepts of mixed-integer linear optimization are introduced. All chapters have several illustrations and geometrical interpretations of the material as well as suggested problems. Nonlinear and Mixed-Integer Optimization will prove to be an invaluable source--either as a textbook or a reference--for researchers and graduate students interested in continuous and discrete nonlinear optimization issues in engineering design, process synthesis, process operations, applied mathematics, operations research, industrial management, and systems engineering.
Capítulos de livros sobre o assunto "Continuous powder synthesis reactor"
1
Fontes, F. A. O., K. K. P. Gomes, Francisca de Fatima P. Medeiros, C. P. Souza, J. F. Sousa e Uilame Umbelino Gomes. "Synthesis of Niobium Carbide from Ammonium Niobium (V) Oxalate Precursor at Low Temperature in Rotating Cylinder Reactor". In Advanced Powder Technology IV, 747–0. Stafa: Trans Tech Publications Ltd., 2005. http://dx.doi.org/10.4028/0-87849-984-9.747.
Texto completo da fonte
2
Chorney, Maureen P., Jerome P. Downey e K. V. Sudhakar. "Development of an Experimentally Derived Model for Molybdenum Carbide (Mo2C) Synthesis in a Fluidized-Bed Reactor". In Advances in Powder and Ceramic Materials Science 2023, 17–25. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-22622-9_3.
Texto completo da fonte
3
Isono, Yasuyuki, Hiroshi Nabetani e Mitsutoshi Nakajima. "Continuous Synthesis of Aspartame Precursor with Membrane Enzyme Reactor — Membrane Extractor System". In Developments in Food Engineering, 686–88. Boston, MA: Springer US, 1994. http://dx.doi.org/10.1007/978-1-4615-2674-2_222.
Texto completo da fonte
4
Choe, Jachoon, Youngwoon Kwon, Jong-Ku Lee e Kwang Ho Song. "Continuous cyclopentenone synthesis with static mixer reactor". In New Developments and Application in Chemical Reaction Engineering, 809–12. Elsevier, 2006. http://dx.doi.org/10.1016/s0167-2991(06)81720-9.
Texto completo da fonte
5
Doraiswamy, L. K. "Reactor Design for Complex Reactions". In Organic Synthesis Engineering. Oxford University Press, 2001. http://dx.doi.org/10.1093/oso/9780195096897.003.0018.
Texto completo da fonteResumo:
Procedures were formulated in Chapter 5 for treating complex reactions. We now turn to the design of reactors for such reactions. Continuing with the ethylation reaction, we consider the following reactor types for which design procedures were formulated earlier in Chapter 4 for simple reactions: batch reactors, continuous stirred reactors (or mixed-flow reactors), and plug-flow reactors. However, we use the following less formal nomenclature: A = aniline, B = ethanol, C = monoethyaniline, D = water, E = diethylaniline, F = diethyl ether, and G = ethylene. The four independent reactions then become Using this set of equations as the basis, we now formulate design equations for various reactor types. Detailed expositions of the theory are presented in a number of books, in particular Aris (1965, 1969) and Nauman (1987). Consider a reaction network consisting of N components and M reactions. A set of N ordinary differential equations, one for each component, would be necessary to mathematically describe this system. They may be concisely expressed in the form of Equation 5.5 (Chapter 5), or . . . d(cV)/dt = vrV (11.1) . . . The use of this equation in developing batch reactor equations for a typical complex reaction is illustrated in Example 11.1.
6
Doraiswamy, L. K. "Reactions and Reactors Basic Concepts". In Organic Synthesis Engineering. Oxford University Press, 2001. http://dx.doi.org/10.1093/oso/9780195096897.003.0009.
Texto completo da fonteResumo:
Organic synthesis is replete with countless classes of reactions, including several that are named after their discoverers (the name reactions), but fortunately they can all be conducted in less than a half-dozen broad types of reactors. Choosing a reactor for a given reaction is based on several considerations and combines reaction analysis with reactor analysis. Thus in this chapter we consider the following aspects of reactions and reactors, much of which should serve as an introduction to chemists and a refresher to chemical engineers: reaction rates, stoichiometry, and rate equations; the basic reactor types, as a prelude to a more rigorous treatment of these in Parts III and IV; transport of mass (represented by reactant and product molecules) and heat across phase boundaries for heterogeneous reactions; and types of laboratory reactors used by chemists and chemical engineers for their specific objectives. The first step in any consideration of reaction rates is the definition of reaction time. This depends on the mode of reactor operation, batch or continuous. For the batch reactor, the reaction time is the elapsed time; whereas for the continuous reactor, it is given by the time the reactant spends in the reactor, called the residence time, that is measured by the ratio of reactor volume to flow rate (volume/volume per unit time with units of time). An equally important consideration is the concept of reaction space (which can have units of volume, surface, or weight), leading to different definitions of the reaction rate. We begin this section by considering different ways of defining the reaction rate based on different definitions of reaction time and space. The basis of all reactor design is an equation for the reaction rate.
7
Lee, Sang-Beom, Sung-Hwan Cho, Young-Whan Park e Huyn-Ku Rhee. "Kinetics of norbornene synthesis and continuous reactor modeling study". In New Developments and Application in Chemical Reaction Engineering, 709–12. Elsevier, 2006. http://dx.doi.org/10.1016/s0167-2991(06)81695-2.
Texto completo da fonte
8
Mark, James E., Dale W. Schaefer e Gui Lin. "Composites". In The Polysiloxanes. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780195181739.003.0011.
Texto completo da fonteResumo:
A relatively new area that involves silicon-containing materials is the synthesis of “ultrastructure” materials (i.e., materials in which structure can be controlled at the level of 100 Å). An example is the “sol-gel” hydrolysis of alkoxysilanes (organosilicates) to give silica, SiO2. The reaction is complicated, involving polymerization and branching, but the overall reaction may be written . . . Si(OR4 + 2H2O → SiO2 + 4ROH (9.1) . . . where the Si(OR)4 organometallic species is typically tetraethoxysilane such as tetraethylorthosilicate (TEOS, with R being C2H5). In this application, the precursor compound is hydrolyzed and then condensed to yield branched polymers. Eventually a continuous swollen gel is formed. The gel is dried at moderately low temperatures to remove volatile species, and then it is fired into a porous ceramic object that can then be densified and machined into a final ceramic part. The production of ceramics by this novel route triggered interest in the ceramics community because of advantages over the conventional powder-processing approach to ceramics. Advantages include (i) the higher purity of the starting materials, (ii) the relatively low temperatures required, (iii) the possibility of controlling the ultrastructure to reduce the microscopic flaws that lead to failure, (iv) the ease with which ceramic coatings can be formed, and (v) the ease with which ceramic alloys can be prepared (e.g., by hydrolyzing solutions of both silicates and titanates). The sol-gel approach has been used to form ceramic-like phases in a variety of polymers. Poly(dimethylsiloxane) (PDMS) is the most popular. PDMS is relatively weak and stands to benefit most from reinforcement. PDMS is easily absorbs the precursor materials generally used in the solgel process. Nearly monodisperse silica microparticles can be obtained using siloxane elastomer mixtures. In some cases, the PDMS has been part of a copolymer, with ureas, imides, amideimides, and dianilines. In other approaches, the particle surface is modified, for example, with a polysiloxane. Siloxane/silica nanocomposites have also been used as “culture-stone-protective materials.” Sol-gel hydrolysis and condensation can be carried out within a polymeric matrix to generate particles of the ceramic material, typically with an average diameter of a few hundred angstroms.
9
Doraiswamy, L. K. "Mixing, Multiple Solutions, and Forced Unsteady-State Operation". In Organic Synthesis Engineering. Oxford University Press, 2001. http://dx.doi.org/10.1093/oso/9780195096897.003.0020.
Texto completo da fonteResumo:
Three important (complicating) possibilities were not considered in the treatment of reactors presented in earlier chapters: (1) the residence time of the reactant molecules need not always be fully defined in terms of plug flow or fully mixed flow; (2) the equations describing certain situations can have more than one solution, leading to multiple steady states; and (3) there could be periods of unsteady-state operation with detrimental effects on performance, that is, transients could develop in a reactor. Actually, reactors can operate under conditions where there is an arbitrary distribution of residence times, leading to different degrees of mixing with consequent effects on reactor performance. Also, multiple solutions do exist for equations describing certain situations, and they can have an important bearing on the choice of operating conditions. And, finally, unsteady-state operation is a known feature of the start-up and shutdown periods of continuous reactor operation; it can also be introduced by intentional cycling of reactants. We briefly review these three important aspects of reactors in this chapter. However, because the subjects are highly mathematical, the treatment will be restricted to simple formulations and qualitative discussions that can act as guidelines in predicting reactor performance. All aspects of mixing in chemical reactors are based on the theory of residence time distribution first enunciated by Danckwerts (1953). Therefore, we begin our discussion of mixing with a brief description of this theory. When a steady stream of fluid flows through a vessel, different elements of the fluid spend different amounts of time within it. This distribution of residence times is denoted by a curve which represents, at any given time, the amount of fluid with ages between t and t + dt flowing out in the exit stream.
10
Mal, Joyabrata. "Continuous Removal and Recovery of Tellurium in an Upflow Anaerobic Granular Sludge Bed (Uasb) Reactor". In Microbial Synthesis of Chalcogenide Nanoparticles, 153–76. CRC Press, 2018. http://dx.doi.org/10.1201/9780429470943-7.
Texto completo da fonteTrabalhos de conferências sobre o assunto "Continuous powder synthesis reactor"
1
Roth, Christian, Gina Oberbossel e Philip Rudolf Von Rohr. "Nanoparticle Synthesis in a Plasma Downstream Reactor – From Plasma Parameters to Nanoparticle Properties". In 13th International Conference on Plasma Surface Engineering September 10 - 14, 2012, in Garmisch-Partenkirchen, Germany. Linköping University Electronic Press, 2013. http://dx.doi.org/10.3384/wcc2.112-115.
Texto completo da fonteResumo:
In the presented study a tubular plasma reactor is investigated, which is normally used for the continuous plasma surface modification of fine-grained powders. The plasma reactor basically consists of a 1.5 m long glass tube with a gas and precursor feed unit at its top and a particle-gas separation unit at the lower end. The power is coupled inductively into the plasma via a coil which is wrapped around the reactor tube. Substrate powders normally pass the discharge tube with high velocity and are functionalized on their way through the plasma in approximately 0.1 s. Possible plasma surface functionalization processes for powders are illustrated in Figure 1.1. The wettability of powders is increased by the formation of polar groups on the surface. Films are deposited on particle surfaces to protect the substrate from harsh environments or for catalytic applications. In recent years, also a new plasma process, which increases the flowability of fine-grained powders, gained increasing attention. Nanostructured SiOx is formed in the plasma and directly deposited on the substrate particle surface. These nanoparticle structures increase the surface roughness of the substrate particles. Thus, the interparticle van der Waals forces are reduced, which leads to a major improvement of the powder flowability. This process shows promise for companies dealing with cohesive granular materials. The feasibility of this process was shown in the past, but at the same time the need for fundamental research in this field was recognized. Which ion density is required to yield in an effective surface modification? What is the thermal load of a substrate particle during the treatment? Which precursor should be used for a maximum improvement of the flowability? In order to answer such questions, we measured axial profiles of plasma parameters in this continuous reactor and studied the nanoparticle synthesis in detail. No substrate powder was fed during these investigations to facilitate probe measurements and to focus on the produced nanoparticles.Silica-like nanoparticles were produced from the four organosilicon monomers hexamethyldisiloxane (HMDSO), tetramethyldisiloxane (TMDSO), tetraethyl orthosilicate (TEOS), and tetramethyl orthosilicate (TMOS) in argon-oxygen gas mixtures. The chemical composition and morphology of the emerging particles and its production rate were studied as a function of process pressure (100 – 400 Pa), plasma power (200 – 350 W), gas velocity (5 – 16 m/s) and gas composition. Langmuir double probe and calorimetric probe measurements allowed determining the axial profiles of electron temperature, positive ion density, and energy influx along the vertical axis of this tubular reactor.
2
Jia, L., e F. Gitzhofer. "Collection of Nano-Powders Generated by Radio Frequency (RF) Plasma Spray Synthesis (PSS) Processing, using a Sampling Probe". In ITSC2005, editado por E. Lugscheider. Verlag für Schweißen und verwandte Verfahren DVS-Verlag GmbH, 2005. http://dx.doi.org/10.31399/asm.cp.itsc2005p1444.
Texto completo da fonteResumo:
Abstract A particle-sampling probe has been designed and constructed for the continuous collection of nano-powders produced by the plasma spray synthesis (PSS) process. The probe comprises a powder sampling line (inner tube), a quench gas line (outer tube) and a water-cooling jacket surrounding the outer tube. A sample holder is disposed at the exit of the inner tube to hold a standard 3.08 mm diameter TEM copper grid which is used to collect the powders by means of the pumping pressure differential. Quenching gas is introduced to the probe, via the outer tube to quench and entrain the as-synthesized clusters. After each sample collection event, the inner tube can be cleaned in-situ by means of a water injection, and then dried using a compressed gas flow. The results obtained to date indicate that the sampling probe location in the plasma reactor and the quenching gas flow rate employed are the most important parameters involved in the satisfactory operation of the sampling probe.
3
Morgan, Eric R., e Tom Acker. "Methanol From Electricity, Water and Carbon Dioxide: Operational Results". In ASME 2015 9th International Conference on Energy Sustainability collocated with the ASME 2015 Power Conference, the ASME 2015 13th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2015 Nuclear Forum. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/es2015-49793.
Texto completo da fonteResumo:
A chemical reactor has been developed that takes only carbon dioxide, water and electricity as inputs and produces a mixture of methanol and water. The system includes an electrolyzer that splits water into oxygen and hydrogen; and data logging capabilities for four temperatures probes, two pressure probes and three flow rates. The methanol synthesis unit was run under a number of flow conditions to help characterize its operation. One day of continuous temperature, pressure and flow rate data from the reactor will be presented to illustrate the system robustness. Finally, synchronized flow, temperature, and pressure data will be presented for the system as it undergoes step changes in the synloop flow rate. The results show that the flow rate through the reactor strongly influences the reactor temperature, which, in turn, influences the rate of methanol production.
4
Kurt, Safa Kutup, Mohd Akhtar, Krishna Deo Prasad Nigam e Norbert Kockmann. "Modular Concept of a Smart Scale Helically Coiled Tubular Reactor for Continuous Operation of Multiphase Reaction Systems". In ASME 2016 14th International Conference on Nanochannels, Microchannels, and Minichannels collocated with the ASME 2016 Heat Transfer Summer Conference and the ASME 2016 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/icnmm2016-8004.
Texto completo da fonteResumo:
Process intensification (PI) via microstructured devices has often been applied by research and development (R&D) and industry for a decade, as they offer a large specific surface area that enhances the mass and the heat transfer. Helically coiled tubular reactors (HCTR) in micro-scale can further increase the performance in terms of transport phenomena, as the secondary flow (Dean vortices) enhances the radial mixing along the tube. Therefore, a narrow residence time distribution (RTD) that is required for the operation of complex chemical reaction systems can be achieved for the long residence times (RTs) at laminar flow regimes In this study, the continuous precipitation of calcium carbonate (CaCO3) was investigated by using a smart scale HCTR, i.e. modular coiled flow inverter (CFI) made of polyvinyl chloride (PVC) tubes (di = 3.2 mm). Modular CFI consists of 90° bends connecting the helical coils in order to enhance the radial mixing further. For precipitation process calcium hydroxide (Ca(OH)2) solution and gaseous CO2/synthetic air mixture were contacted prior to the reactor inlet via a Y-mixer. Slug flow profile was maintained and CaCO3 was precipitated along the reactor tube. To avoid further reaction of CaCO3 with water that is saturated with CO2 (pH ≲ 8.6), which promotes the consecutive parallel reaction forming soluble calcium bicarbonate (Ca(HCO3)2), the RT of the reactor was easily varied by changing the tube length of the modular CFI. Precipitated CaCO3 particles with a conversion of ca. 90% were separated from the suspension by vacuum filtration. Influence of volumetric flow ratio of the gases (R = V̇CO2/V̇air) and the RT were investigated on the precipitation process at constant flow rates. A comparison is presented between a batch reactor and a modular CFI. Results showed that narrower particle size distribution (PSD) with median particle diameters (d50,2) around 28 μm and more uniform morphology can be achieved by using a CFI for the continuous production of the powders.
5
Perala, Sivaramakrishna, Madan Avulapati, Ravikrishna R.V. e Sanjeev Kumar. "Continuous Synthesis of Calcium Carbonate Nanoparticles using a Mist Flow Reactor". In 5th Asian Particle Technology Symposium. Singapore: Research Publishing Services, 2012. http://dx.doi.org/10.3850/978-981-07-2518-1_164.
Texto completo da fonte
6
Srinivasan, Suresh, Joe Gillham e Jessica Marshall M. "High Density Radiation Shielding Of Cwc-RSB Composite For Fusion Reactor: A Critical Review". In Euro Powder Metallurgy 2024 Congress & Exhibition. EPMA, 2024. http://dx.doi.org/10.59499/ep246283660.
Texto completo da fonteResumo:
Development of high-density radiation shielding is one of the key aspects in deploying new nuclear reactors (Gen IV fission and fusion) to decarbonize global energy production. The current candidate materials based on refractory metals and tungsten (W)-based alloys do not yet meet the engineering requirements of a practical power generating compact spherical tokamak (cST) reactor. Radiation shielding materials must fulfil not only the materials challenges and radiological safety requirements, but also the regulatory requirements in the case of accidents. Cemented tungsten carbide (cWC)-reactive sintered boride (RSB) composites are promising candidate for compact radiation-dense nuclear armour. This review presents the synthesis and characterization of cWC-RSB materials under various processing conditions for nuclear radiation shielding. This includes simulation of compositions and synthesis parameters of cWC-RSB composites using the CALPHAD method. The radiation attenuation capabilities, radiation damage and mechanical properties of cWC-RSP composites under various scenario, simulations and conditions are discussed.
7
Siddiqui, Mohammad Atif, Mohammad Nishat Anwar, Ahmad Faiz Minai, Akhlaque Ahmad Khan, Mohammad Naseem e Abdul Jabbar. "A Direct Synthesis based Sliding Mode Control of a Nonlinear Continuous Stirred Tank Reactor". In IECON 2022 – 48th Annual Conference of the IEEE Industrial Electronics Society. IEEE, 2022. http://dx.doi.org/10.1109/iecon49645.2022.9969082.
Texto completo da fonte
8
Palanisamy, Barath, e Brian Paul. "Ultrasound Induced Synthesis of CdS Nanocrystals Under Continuous Flow". In ASME 2013 International Manufacturing Science and Engineering Conference collocated with the 41st North American Manufacturing Research Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/msec2013-1225.
Texto completo da fonteResumo:
Cadmium sulfide nanoparticles generally exhibit quantum confinement effects when the particle size is less than 10 nm and approaches the Bohr exciton radius. It is a widely used buffer material in solar cells owing to its wide band transmission of solar light and hence used as a window layer in photovoltaic devices. Sonochemical synthesis permits the rapid heating of reactant baths by acoustic cavitation leading to high local temperatures. In this research, results from batch trials for heating and synthesis are reported. These results were used to design experiments for the continuous synthesis of CdS nanoparticles using a sonochemical reactor consisting of a flow cell and a high intensity horn. By utilizing the continuous synthesis approach a more than hundred fold reduction in processing time over batch synthesis for similar product was reported.
9
Schael, Frank, Krishna Nigam e Patrick Rojahn. "Green engineering approach with microstructured coiled flow inverter for CMF and HMF continuous flow synthesis". In 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/ikvz3189.
Texto completo da fonteResumo:
Since the first publication of the 12 green engineering principles by Anastas and coworkers in 2003 a considerable body of literature developed the idea and its systematic application further. Nowadays several chemical process assessment tools include green engineering principles. This talk gives an overview on the status of green engineering in process assessment and presents a process development example following green engineering principles such as employment of renewable rather than depleting feedstocks and maximization of mass, energy, space and time efficiency among others.
In particular, investigations of the technical synthesis of 5-(hydroxymethyl)furfural HMF and 5-(chloromethyl) furfural CMF from sugars and sugar containing waste streams is presented. HMF and CMF attracted a lot of attention in recent literature as potential candidates for new platform chemicals. However, mainly studies of batch processes are so far available.
In continuation of earlier investigations process development for a continuous flow synthesis of HMF and CMF is performed by means of a reactive extraction which allows to beneficially combine separation and reaction unit operations in a single processing step. A coiled flow inverter reactor concept with reactor diameters on the scale of millimeter and submillimeter is used. The hydrodynamic properties of the reactor concept in conjunction with small reactor diameters assure efficient heat and mass transfer, narrow residence time distribution and improved safety when compared to regular batch processes. The continuous flow approach allows more easy adaption to changing processing demands and better process control.
In systematic investigations environmentally benign extraction solvents, reaction temperature, initial sugar concentrations, and reactor geometry is varied. Kinetic details as well as the influence of flow regimes of the two-phase mixture and hydrodynamic aspects of the reactor operation are elucidated. This information is of relevance for optimization for a later scale-up of the process in line with green engineering principles.
10
Aktekin, B., e T. Öztürk. "Thermal Plasma Synthesis of Mg-Ni Nanoparticles". In ITSC 2016, editado por A. Agarwal, G. Bolelli, A. Concustell, Y. C. Lau, A. McDonald, F. L. Toma, E. Turunen e C. A. Widener. DVS Media GmbH, 2016. http://dx.doi.org/10.31399/asm.cp.itsc2016p0412.
Texto completo da fonteResumo:
Abstract In this study, a 30 kW RF plasma reactor is used to synthesize metallic (Ni) and intermetallic (Mg2Ni) nanoparticles along with carbon-encapsulated Ni. The system was configured with injection probes at the top and bottom of the torch to facilitate the synthesis of compounds as well as core-shell particle structures. Materials used as precursors include methane, Ni, Mg, and pre-alloyed Mg2Ni powder. By feeding Ni together with methane, nickel nanoparticles encapsulated with 6-10 layers of graphite were produced. The core-shell particles and other samples collected were analyzed using X-ray diffraction and electron imaging techniques and were found to be spherical in shape and less than 100 nm in diameter.