Flow Synthesis System Research Articles

Bayesian optimization of radical polymerization reactions in a flow synthesis system

Bayesian optimization of radical polymerization reactions in a flow synthesis system

Flow synthesis of conjugated polymers: exploring the effects of solvent and catalyst on molecular weight

The high reproducibility of the flow synthesis system enabled accurate investigation of the relationship between reaction conditions and molecular weight in Stille polycondensation of conjugated polymers.

Flow Synthesis of L-α-Glycerylphosphorylcholine: Studies on Synthetic Routes Applicable to a Flow Reactor and Optimization of Reaction Conditions.

L-α-Glycerylphosphorylcholine (L-α-GPC) has mainly been produced by two methods: extraction from plants rich in phosphatidylcholine and chemical synthesis. However, production through extraction involves difficult processes, such as fermentation, extractions and ripening, and conventional chemical synthesis methods with high-cost reactants and a batch reactor. These methods are not ideal for large-quantity production. Thus, it is important to develop a simple production method of L-α-GPC, which is suitable for mass production without the need for expensive reactants. Here, we studied synthetic L-α-GPC methods that are applicable to a flow synthesis system, which can provide selectivity, reproducibility, scalability, and a high yield in short reaction time using inexpensive starting materials. We developed a two-step synthetic route to produce L-α-GPC, including the synthesis of phosphoryl choline using choline chloride and phosphoryl oxychloride (POCl3) as a first step and synthesis of L-α-GPC by reacting phosphoryl choline with (R)-(-)-3-chloro-1,2-propanediol (CPD) as a second step under basic conditions. Both steps were separately performed in a customized flow reactor, and reaction conditions were optimized. Finally, phosphoryl choline and L-α-GPC, the products first and second reactions, were successfully synthesized with high conversion yields of 97% and 79%, respectively.

Femtosecond laser-engineered 3D microfluidic chips: Synthesis system sprouting highly efficient multiphase organic reactions

Recent developments in the utilization of microfluidic chips (MFCs) have shown their potential utility in multiphase organic synthesis by enabling efficient organic reactions in flow chemistry. However, MFCs technology has been wandering in the laboratory of small dose synthetic routes, which is limited to the level of "tiny" fluid flux. To address this issue, we herein report the first case of the chips with high-throughput 3D channels produced by femtosecond laser being used to create a time-saving, cost-effective and risk-free approach suitable for large-scale flow synthesis. Several multiphase reactions have been successfully prepared on demand in our designed flow synthesis system containing 3D MFCs: 1) benzyl alcohol was converted to benzaldehyde in 3 min with a yield of 97.50% by liquid-liquid two-phase transfer catalytic oxidation; 2) organozinc reagents and α-cyano carbonyl carbon compounds were synthesized by solid-liquid two-phase metal insertion reaction in 7 min, and the yield was up to 100%; 3) benzoic acid was synthesized by gas-liquid two-phase carboxylation reaction in 2.8 s with a yield of 96%. Significant gains in production rate result from the effective scaling of flow reactors from microliters per hour in MFCs to intermediate milliliters per minute without affecting mass transport performance. Meanwhile, our 3D MFCs show excellent mass and heat transfer efficiency in large-scale industrial units, breaking through the bottleneck in this field. As a result, it is possible to imagine the creation of a new, streamlined flow synthetic technique via MFCs for green multiphase organic synthesis.

One-step continuous flow synthesis of aminopropyl silica-coated magnetite nanoparticles

One-step continuous flow synthesis was developed and applied for the preparation of amino propyl silica-coated nanoparticles (APSMNPs). This was accomplished in one step through continuous flow synthesis and amino propyl silica coating. Magnetite nanoparticles (MNPs) are generated in situ using a continuous flow synthesis system before being coated with amino propyl silica using tetraethyl orthosilicate (TEOS) condensation process and 3-aminopropyl triethoxysilane (APTES) condensation process in different ratios. The effect of the molar ratio of TEOS to APTES on the structure and physicochemical properties of the corresponding APSMNPs was examined by N2 adsorption–desorption isotherm, transmission electron microscope (TEM), vibrating sample magnetometer (VSM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscope energy dispersive X-ray (SEM-EDX). This continuous flow process has advantages such as easy scalability, convenient production, easy control, an economical method with less time and reagents than traditional synthetic methods. It is a good choice for industrial production of APSMNPs.

A low cost and open access system for rapid synthesis of large volumes of gold and silver nanoparticles

Rapid synthesis of nanomaterials in scalable quantities is critical for accelerating the discovery and commercial translation of nanoscale-based technologies. The synthesis of metal nanogold and silver in volumes larger than 100 mL is not automatized and might require of the use of harsh conditions that in most cases is detrimental for the production of nanoparticles with reproducible size distributions. In this work, we present the development and optimization of an open-access low-cost NanoParticle Flow Synthesis System (NPFloSS) that allows for the rapid preparation of volumes of up to 1 L of gold and silver nanoparticle aqueous solutions.

Reproducible and rapid synthesis of a conjugated polymer by Stille polycondensation in flow: Effects of reaction parameters on molecular weight

The batch-to-batch variations in molecular weight and molecular weight dispersity (Đ) values are large for conjugated polymers synthesized by step-growth polymerization, which can lead to irreproducible device performance. We developed a rapid flow synthesis system that can perform step-growth polymerizations of conjugated polymers in a reproducible manner by utilizing nitrogen gas as a carrier. The use of gas carrier, instead of organic solvents or fluorinated oils, eliminates the common diffusion problems at the beginning and the end of the reaction stream to the carrier fluid. Without the diffusion problem, our system provides high reproducibility and uniform reaction conditions in all regions of reaction stream. To highlight the performance of our flow system, we conducted Stille polycondensations to synthesize a representative conjugated polymer, PTB7. We found that PTB7 with a number average molecular weight (Mn) over 30 kDa was synthesized in only 3 min, with very low deviations of 2.6% and 3.1% for Mn and Đ values, respectively, compared to deviations of 66% for Mn and 43% for Đ in control reactions using pure solvent as a carrier. The effect of catalyst loading and reaction temperature was also studied, which enabled tuning the Mn of PTB7 within the range of 30.6–57.9 kDa. The quality of PTB7 synthesized in our system was also confirmed by fabricating photovoltaic devices which gave maximum power conversion efficiency of 7.02% with PC71BM as an acceptor.

High Throughput Synthesis and Screening of Oxygen Reduction Catalysts in the MTiO3 (M = Ca, Sr, Ba) Perovskite Phase Diagram.

A library of 66 perovskite BaxSryCazTiO3 (x + y + z = 1) samples (ca. three grams per sample) was made in ca. 14 h using a high-throughput continuous hydrothermal flow synthesis system. The as-synthesized samples were collected from the outlet of the process and then cleaned and freeze-dried before being evaluated individually as oxygen reduction catalysts using a rotating disk electrode testing technique. To establish any correlations between physical and electrochemical characterization data, the as-synthesized samples were investigated using analytical methods including BET surface area, powder X-ray diffraction (PXRD) and in selected cases, transmission electron microscopy (TEM). The aforementioned approach was validated as being able to quickly identify oxygen reduction catalysts from new libraries of electrocatalysts.

Size-controlled flow synthesis of metal-organic frameworks crystals monitored by in-situ ultraviolet–visible absorption spectroscopy

Size-controlled flow synthesis of nanoporous particles are of considerable interest for future industrial applications, however, is facing challenges due to lack of in-situ method for size-characterization in fluidic environment. We present that ultraviolet-visible (UV–vis) absorption spectroscopy can be integrated into a flow-synthesis system which was produced by femtosecond laser micromachining. The shift of the absorption peak position of the ex-situ and in-situ UV–vis spectra correlates to variation of size of porous metal-organic frameworks crystals. ZIF-67 crystals with a size in the range from 200 nm to 1025 nm are fabricated with the assistance of tri-ethylamine under monitoring of in-situ UV–vis spectra. The ZIF-67 crystals are converted into nanoporous carbons particles with controlled sizes. These materials show size-dependent performance in Na-ion battery and size-independent performance in metal/H2O seawater battery.

Optimized ultrafast flow synthesis of CON-type zeolite and improvement of its catalytic properties

The fast synthesis of CON-type zeolite could be an option for mass production using a continuous flow synthesis system.

A numerical study on heat transfer enhancement and design of a heat exchanger with porous media in continuous hydrothermal flow synthesis system

Abstract The aim of this study is to use a new configuration of porous media in a heat exchanger in continuous hydrothermal flow synthesis (CHFS) system to enhance the heat transfer and minimize the required length of the heat exchanger. For this purpose, numerous numerical simulations are performed to investigate performance of the system with porous media. First, the numerical simulation for the heat exchanger in CHFS system is validated by experimental data. Then, porous media is added to the system and six different thicknesses for the porous media are examined to obtain the optimum thickness, based on the minimum required length of the heat exchanger. Finally, by changing the flow rate and inlet temperature of the product as well as the cooling water flow rate, the minimum required length of the heat exchanger with porous media for various inlet conditions is assessed. The investigations indicate that using porous media with the proper thickness in the heat exchanger increases the cooling rate of the product by almost 40% and reduces the required length of the heat exchanger by approximately 35%. The results also illustrate that the most proper thickness of the porous media is approximately equal to 90% of the product tube's thickness. Results of this study lead to design a porous heat exchanger in CHFS system for various inlet conditions.

Highly effective synthesis of a cobalt(ii) metal-organic coordination polymer by using continuous flow chemistry.

The coordination polymer [Co2L4(H2O)2]·CH3CN·H2O (HL = (E)-2-[2-(4-chlorophenyl)vinyl]-8-hydroxyquinoline) has been achieved with 95% yield by using an Asia flow synthesis system (chip reactor). Compared with the conventional batch-type methods such as diffusion, reflux and solvothermal reactions, higher yielding reactions carried out in a flow reactor have demonstrated that this technique is a powerful strategy to obtain coordination compounds.

Rapid hydrothermal flow synthesis and characterisation of carbonate- and silicate-substituted calcium phosphates

A range of crystalline and nano-sized carbonate- and silicate-substituted hydroxyapatite has been successfully produced by using continuous hydrothermal flow synthesis technology. Ion-substituted calcium phosphates are better candidates for bone replacement applications (due to improved bioactivity) as compared to phase-pure hydroxyapatite. Urea was used as a carbonate source for synthesising phase pure carbonated hydroxyapatite (CO3-HA) with ≈5 wt% substituted carbonate content (sample 7.5CO3-HA) and it was found that a further increase in urea concentration in solution resulted in biphasic mixtures of carbonate-substituted hydroxyapatite and calcium carbonate. Transmission electron microscopy images revealed that the particle size of hydroxyapatite decreased with increasing urea concentration. Energy-dispersive X-ray spectroscopy result revealed a calcium deficient apatite with Ca:P molar ratio of 1.45 (±0.04) in sample 7.5CO3-HA. For silicate-substituted hydroxyapatite (SiO4-HA) silicon acetate was used as a silicate ion source. It was observed that a substitution threshold of ∼1.1 wt% exists for synthesis of SiO4-HA in the continuous hydrothermal flow synthesis system, which could be due to the decreasing yields with progressive increase in silicon acetate concentration. All the as-precipitated powders (without any additional heat treatments) were analysed using techniques including Transmission electron microscopy, X-ray powder diffraction, Differential scanning calorimetry, Thermogravimetric analysis, Raman spectroscopy and Fourier transform infrared spectroscopy.

Numerical modelling of hydrothermal fluid flow and heat transfer in a tubular heat exchanger under near critical conditions

Continuous hydrothermal flow synthesis processes are of interest for the manufacture of nanoparticle metal oxides. In such processes, nanoparticle nuclei (in a slurry) which are initially formed, may continue to grow and agglomerate to generate larger particles as they pass through the synthesis apparatus. These processes can widen the size distribution and also affect the ultimate particle shape in the recovered product. Therefore, fast cooling or quenching the initial nanoparticle slurry using a highly efficient heat exchanger may minimise or stop further crystallisation/agglomeration processes. This may be achieved by optimising the design of the heat exchanger based on detailed examination of flow patterns and heat transfer profiles using a computational fluid dynamics (CFD) modelling approach. The predicted flow and heat transfer patterns in the heat exchanger can also provide detailed information for the identification of any heat transfer deterioration or hot spots where further reactions may occur. This paper employs a CFD modelling approach to simulate the heat transfer processes in a tubular heat exchanger of a continuous hydrothermal flow synthesis system and also to examine the effect of various operating conditions, including inlet temperature and flowrate of hot slurry and inlet flowrate of cooling water, on the fluid and thermal features in the heat exchanger. The simulated results show that the predicted temperature and heat transfer coefficient are in good agreement with experimental measurements.

Direct syntheses of La n+1Ni nO 3n+1 phases ( n=1, 2, 3 and ∞) from nanosized co-crystallites

A new direct route for the “bottom up” syntheses of phases in the La n +1Ni n O 3 n +1 series ( n=1, 2, 3 and ∞) has been achieved via single-step heat treatments of nanosized co-crystallized precursors. The co-crystallized precursors were prepared using a continuous hydrothermal flow synthesis system that uses a superheated water flow at ca. 400 °C and 24.1 MPa to produce nanoparticulate slurries. Overall, a significant reduction in time and number of steps for the syntheses of La 3Ni 2O 7 and La 4Ni 3O 10 was achieved compared with more conventional synthesis methods, which typically require multiple homogenization and reheating steps over several days.

Direct Syntheses of Mixed Ion and Electronic Conductors La4Ni3O10 and La3Ni2O7 from Nanosized Coprecipitates

Nanoparticle coprecipitates of lanthanum hydroxide and nickel hydroxide were synthesized in a continuous hydrothermal flow synthesis system. Two such coprecipitates with the appropriate La:Ni molar ratios were subsequently directly converted to phase-pure La4Ni3O10 and La3Ni2O7, respectively, via a single heat-treatment step in each case.

Direct Synthesis of Nanosized NiCo2O4Spinel and Related Compounds via Continuous Hydrothermal Synthesis Methods

A series of crystalline homometallic and heterometallic cobalt and nickel hydroxides and oxides were prepared using a continuous hydrothermal flow synthesis system. In all syntheses, the relevant m...