Microreactor technology comes to Nizhny Novgorod | Pravada.ru

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Nizhny Novgorod State University named after Lobachevsky will become the main center of the project to establish the National Center for High Chemical Technologies. On April 18-19, professor of microfluidic chemistry and technological processes at the Eindhoven University of Technology, Volker Hessel, will pay a visit to the region.

Hessel will deliver a report about “the possibilities of application of microstructure reactors in various industries.” The report will be devoted to the European experience and technology transfer to Russia. To date, microreactor technology is used in Europe, USA and Japan. The technology is used in the pharmaceutical industry, oil refining, and other areas.

The use of modern technologies will make production more secure and more efficient.  The microreactor technology allows to cut production costs by reducing production area  (from 100 to 1000 times). It also reduces the environmental risks of chemical production, production time and, most importantly, the time from the development of chemical plant before it is launched into operation.

In Russia, the project starts at multiple sites, with the basic one located in the Nizhny Novgorod State University. The university is a Russian center of chemical science and technology. The level of fundamental and theoretical studies conducted by Nizhny Novgorod chemists, according to Professor Hessel, meets highest modern standards.

Regional centers will be located in Novosibirsk, St. Petersburg and Tver. The centers will deal with solving applied problems on each of key areas in the field of chemical micro-and nanotechnology.

The new project will involve both domestic and foreign experts. It is assumed that the main university of Nizhny Novgorod and will prepare new specialists.  Students and graduate students will be given an opportunity to undergo internship abroad.

According to experts, the establishment of the National Center for High Chemical Technologies in the Nizhny Novgorod region will lead to the modernization of existing enterprises, by introducing latest chemical technologies, creating new industries and, as a consequence, creating new jobs. This will significantly increase tax revenues, develop scientific and educational base and increase the investment appeal of the region.

SOURCE:  http://english.pravda.ru/news/russia/18-04-2013/124333-nizhny_novgorod_microreactor-0/

Microreactor speeds nanotech particle production by 500 times | Oregon State University

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CORVALLIS, Ore. – Engineers at Oregon State University have discovered a new method to speed the production rate of nanoparticles by 500 times, an advance that could play an important role in making nanotechnology products more commercially practical.

The approach uses an arrayed microchannel reactor and a “laminated architecture” in which many sheets, each with thousands of microchannels in them, are stacked in parallel to provide a high volume of production and excellent control of the processes involved.

Applications could be possible in improved sensors, medical imaging, electronics, and even solar energy or biomedical uses when the same strategy is applied to abundant materials such as copper, zinc or tin.

A patent has been applied for, university officials say. The work, just published in the journal Nanotechnology, was done in the research group of Brian Paul, a professor in the OSU School of Mechanical, Industrial and Manufacturing Engineering.

“A number of new and important types of nanoparticles have been developed with microtechnology approaches, which often use very small microfluidic devices,” said Chih-hung Chang, a professor in the OSU School of Chemical, Biological and Environmental Engineering, and principal investigator on the study.

“It had been thought that commercial production might be as simple as just grouping hundreds of these small devices together,” Chang said. “But with all the supporting equipment you need, things like pumps and temperature controls, it really wasn’t that easy. Scaling things up to commercial volumes can be quite challenging.”

The new approach created by a research team of five engineers at OSU used a microreactor with the new architecture that produced “undecagold nanoclusters” hundreds of times faster than conventional “batch synthesis” processes that might have been used.

“In part because it’s faster and more efficient, this process is also more environmentally sensitive, using fewer solvents and less energy,” Chang said. “This could be very significant in helping to commercialize nanotech products, where you need high volumes, high quality and low costs.”

This research, Chang said, created nanoparticles based on gold, but the same concept should be applicable to other materials as well. By lowering the cost of production, even the gold nanoclusters may find applications, he said, because the cost of the gold needed to make them is actually just a tiny fraction of the overall cost of the finished product.

Nanoparticles are extraordinarily tiny groups of atoms and compounds that, because of their extremely small size and large surface areas, can have unusual characteristics that make them valuable for many industrial, electronic, medical or energy applications.

SOURCE:  http://oregonstate.edu/ua/ncs/archives/2010/nov/microreactor-speeds-nanotech-particle-production-500-times

Self-contained chemical synthesis | Chemistry World

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Scientists in the UK have used reactors made on a 3D printer to complete a three stage organic synthesis. The reagents, catalyst and purification step for the synthesis are completely integrated into the chambers of the sealed reactor. When the reactor is rotated, gravity pulls reactants through the different chambers to complete the synthesis.

Initially, Leroy Cronin, who lead the work at the University of Glasgow, had envisaged a ‘Rubik’s cube for synthesis’, where different manipulations of the reactor would produce different products. ‘The code, like opening a safe, would be in the rotation,’ he explains. ‘I thought it was genius. My group told me I was stupid.’ The team convinced Cronin to start with an easier L-shaped three step reactor, but he still plans to create the Rubik’s cube in the future.

A three-step organic reaction sequence was performed in the L-shaped reactor. The sequence began with a Diels–Alder cyclisation followed by formation of an imine and then hydrogenation of the imine to the corresponding secondary amine.

The team’s next challenge is to use 3D printing to trap reactive intermediates within the device. Research into this is already underway. The scientists suggest that sensors could also be included to monitor the reactions. ‘Closed loop synthesis–sensor–synthesis would be a revolution,’ says Cronin.

Filipe Vilela from Max Planck Institute of Colloids and Interfaces, Potsdam, Germany, an organic synthsis expert, says that apart from having an incorporated catalyst and purification step, which leads to a stand-alone reactor for a multi-step synthesis and purification, this technology stands out for its inexpensive nature and will soon rival other multi-step reactors like micro and millifluidic devices.

‘The 3D platform allows for the reproduction of a reactive system in any laboratory that has a 3D printer,’ says Vilela. ‘Given the open-source nature of this technology, a scientist can download the 3D printing files made available by the authors and load the 3D printer with the materials originally used to reproduce the system.’ He envisages that in the future, with this technology, experimental protocols will have the simple sentence “3D printing verified” to validate a particular reaction and/or system.

SOURCE:  http://www.rsc.org/chemistryworld/2013/06/organic-synthesis-reactor-3d-printer

Industrial nitroglycerin made fast and safe | Chemistry World

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A microreactor (Credit: Micronit)Since the invention of nitroglycerin in the mid nineteenth century, people have been trying to find safer ways to manufacture the highly unstable liquid explosive. Now, researchers at the Fraunhofer Institute for Chemical Technology (ICT) in Pfintzal, Germany, have come up with what might be the safest approach yet – using microreactors to produce nitroglycerin continuously rather than in batches. This is not only safer but also quicker, facilitating a tenfold increase in production rate.

Nitrogylcerin is made by adding glycerol, a simple hydrocarbon with three hydroxyl groups, to a mixture of sulfuric acid and nitric acid. The reaction is extremely exothermic, but if the temperature gets too high – somewhere above 30°C for example – ‘runaway’ can occur, increasing dramatically the risk of explosion.

Therefore manufacturers continually cool the reaction mixture and – in the traditional batch process – add the glycerol drop-by-drop to the acid to give time for the heat to dissipate and maintain an excess of acid, essential to ensure complete nitration of the all the hydroxyl groups.

‘This is quite old fashioned chemistry,’ says Stefan Löbbecke, deputy director for explosive materials at the Fraunhofer ICT. Switching to a continuous process in a microreactor means working with much smaller quantities – safer for several reasons. It makes it is easier to control the overall temperature and the degree of mixing, which is important to avoid localised temperature variations and dangerous ‘hotspots’. It also makes it easier to control the decomposition products. And in the event of something going very wrong, the resulting explosion would be much smaller.

The microreactor is a hand-sized clear polymer tile with an internal channel that meanders across the plane. The internal channel has two entrances but only one exit – the reactants are brought together at the start and then mixed as they move through the microreactor by turbulence caused by a complex pattern of grooves and ridges on the sides of the channel.
To scale up production, you simply add more microreactors in parallel. A single microreactor might be used to make 10-50kg  of nitroglycerine per day, says Löbbecke. But his group has experimented with production at 2-3 tonnes per week by ‘numbering up’ the microreactors.

That said, this is not an approach for bulk production of nitroglycerin. Low grade product, primarily for the mining and construction industries, can be made cheaply in bulk already. Where this approach is a real advantage, says Löbbecke, is in the manufacture of smaller quantities of nitroglycerin, and other nitric esters, at very high grades for use in the pharmaceutical industry. Nitroglycerin is not only a powerful explosive but also a potent drug (sometimes called glyceryl trinitrate), widely used for treating angina and other heart problems.

The improved safety of the approach reduces costs for the manufacturer, as does the higher rate of production. The microreactor approach is already in use industrially, although Löbbecke declined to say where owing to commercial sensitivities.

SOURCE:  http://www.rsc.org/chemistryworld/2012/06/industrial-nitroglycerin-made-fast-and-safe

Microreactors tame osmium tetroxide | Chemistry World

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Researchers in South Korea and India have made microfluidic reactors that safely harness the synthetically powerful but noxious catalyst osmium tetroxide.

Dong-Pyo Kim at POSTECH in Pohang, South Korea, and colleagues trapped OsO4 in poly(4-vinylpyridine) (P4VP) ‘nanobrushes’ on the inner walls of silicone microreactors. Their reactors catalysed dihydroxylation and oxidative cleavage – steps important in natural product, pharmaceutical and fine chemical synthesis – of 10mmol of various olefins with yields of more than 90%. Only 50µg of OsO4 was needed, making the microreactor catalyst 50 times more efficient than bulk supported systems.

OsO4 powers reactions like the chemistry Nobel prize winning Sharpless asymmetric dihydroxylation, but is toxic and unusually volatile, and therefore produces deadly fumes. ‘Many researchers have tried to stabilise or immobilise it on a polymer or inorganic substrate,’ Kim tells Chemistry World. ‘But leaching and exposure to the environment is inevitable in a bulk reaction system.’

So Kim’s team sought to trap OsO4 in microreactors by moulding two pieces of silicone holding mirror image nano-sized channels using soft lithography. As silicone normally swells in organic solvents they spin-coated the channels with protective polyvinylsilazane (PVSZ) layers, which they then bonded PV4P nanobrushes to. After putting the two halves of silicone together, the researchers infused the microreactor with aqueous OsO4.

Initially, catalytic activity disappeared after just a day. To boost the reactor’s stability, the team reduced OsO4 to a dark blue oxoosmium(VI) complex by feeding tetrahydrofuran through it after catalyst loading. In testing on biomass-based olefins, dihydroxylation reactions exceeded 98% conversion in 10 minutes, and oxidative cleavage reached similar levels in seven minutes. But the reactor’s volume limits it to around 1mmol of product per hour.

Reactor performance did not change significantly after 10 hours’ continuous use, or three months’ storage. Reaction mixtures contained just 30–50ppb osmium, around 100 times lower than other reported systems, Kim says. ‘We are now working on scale-up of our reactor system for possible industrial application and further developing microchemical systems for hazardous heterogeneous catalysts,’ he adds.

Paul Watts, who researches microfluidic continuous flow chemistry at Nelson Mandela Metropolitan University in Port Elizabeth, South Africa, notes the increasing interest in such reactors’ safety potential. He says Kim’s team’s reactor ‘provides a very elegant way to use OsO4 within research’. ‘I envisage the methodology being of significant use to other organic chemists,’ he adds.

SOURCE:  http://www.rsc.org/chemistryworld/2013/04/microreactors-tame-poisonois-osmium-tetroxide

MicroReactors Eyed For Industrial Use | Chemical and Engineering News

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Chemistry in microreactors has been touted as faster, safer, and cheaper, so it’s not surprising that interest in such systems continues to intensify. Microreactors typically consist of plates containing microstructures that define a very small reaction volume, as well as pumping accessories for continuous operation. Now that microreactors are available off the shelf at modest cost, more and more companies engaged in fine chemicals production are testing the technology.

Recently, Sigma-Aldrich took the plunge. Last February, it installed a standard Cytos Lab System microreactor at its R&D facilities in Buchs, Switzerland. Developed by CPC (Cellular Process Chemistry Systems GmbH, Frankfurt), the system has a list price of about $187,000. Sigma-Aldrich is in good company: Sixteen other pharmaceutical and fine chemicals producers are interested in CPC’s technology, according to Sigma-Aldrich’s Fabian Wahl, manager of R&D for Europe. Wahl’s group is spearheading the firm’s technology evaluation.

The key feature of microchemical systems is the high ratio of surface area to volume. That ratio is 200 for a microreactor with a reaction volume of 1.5 mL, such as that of CPC’s, and only 0.6 for a 1- m3 reactor. Mass transfer, heat transfer, and mixing are vastly more efficient in a microreactor, allowing far more precise reaction control and far better product quality control than can be achieved with conventional reactors, Wahl says.

In addition, an optimized process can be run at any scale without further R&D by simply running in parallel as many reactors as are required. Such a mode of operation is easily executed because microreactor systems typically are modular.

The technology would reduce the cost of scale-up and resources deployed to develop safe and stable processes, Wahl concludes. It is useful and practical for Sigma-Aldrich’s businesses, particularly for developing and making catalog products.

Many of Sigma-Aldrich’s catalog products are produced under usual lab conditions in flasks of up to 20 L. Of the more than 2,000 compounds in this portfolio, about 800 could be produced in microreactors with little or no process modification, Wahl says. For such cases, microreactors would reduce reaction time and cost.

For example, the condensation of 2-trimethylsilylethanol and p-nitrophenyl chloroformate to produce 2-(trimethylsilyl)ethyl 4-nitrophenyl carbonate requires 14 hours to complete in a conventional setup but only 18.4 minutes in a microreactor. Because contact between reagents and products is so brief, the possibility that the desired product will degrade or that by-products will be formed is vastly reduced, Wahl says.

Even more attractive is the opportunity microreactors offer to run problematic chemistries, such as those that are highly exothermic, produce unstable products, or form difficult-to-separate side products. Wahl’s team has explored use of microreactors for two such reactions.

The first is ester hydrolysis to produce an alcohol that readily degrades. Wahl declines to identify the ester or the alcohol. He says only that Sigma-Aldrich could not keep up with the demand for the alcohol because yield deteriorates as the reaction is scaled up: 70% at 5 L, 35% at 20 L, and 10% at 100 L.

Because Sigma-Aldrich’s original process requires an insoluble component, it could not be carried out in a microreactor. “We had to change the chemistry, but we did not know in which way,” Wahl says. With microreactors, they found out quickly.

It took less than a day to run a model reaction under 12 different conditions. A substrate that yields a stable alcohol was used so as not to complicate process development with degradation of the alcohol product of the actual substrate. After the best conditions were identified for the model system, it took only two hours to optimize the reaction of the actual substrate.

The second problematic chemistry tested by Wahl’s team is preparation of methylenecyclopentane from a substrate that Wahl does not wish to disclose. The reaction is highly exothermic, and process control is not good under conventional conditions. Furthermore, up to 30% of the yield consists of the more thermodynamically stable product, 1-methylcyclopentene, which is difficult to separate. For these reasons, production of methylenecyclopentane had been discontinued.

Using the CPC microreactor, Wahl’s team devised a reaction that gives 70% conversion, no by-product, and a throughput of 300 g per hour, Wahl says. A 70% conversion with no by-product is better than a higher conversion with some by-product because separating the product from the precursor is easier than separating it from the by-product, he explains.

Wahl expects microreactor technology also to have a positive impact on Sigma-Aldrich’s custom synthesis business, in which rapid process development is a competitive advantage. His expectation that microreactors would reduce development time by 40% has been met so far. Thus, Sigma-Aldrich is inclined to adopt microreactor technology more widely, he says.

The major drawback is the inability to work with gases and insoluble reagents. A minor one is the fact that the CPC microreactors are fabricated from steel, which is chemically sensitive. CPC is now testing microreactors made with Hastelloy, the chemically resistant material widely used in conventional reactors.

The CPC microreactors are easy to work with, Wahl says. The most common problem is blockage, which often is solved with one call to CPC’s hotline. Changeover from one process to another requires only a five-minute rinse with solvent.

Last month, Wahl visited Massachusetts Institute of Technology for a close look at the microchemical system being developed by Klavs Jensen, a professor of chemical engineering. The MIT system is different from CPC’s in three major ways. First, the reaction volume is in the microliter range, making it possible to carry out a lot of experiments with minuscule amounts of materials. Second, the reactor is made of silicon, which can be oxidized to form glass surfaces familiar to chemists. Because silicon and silicon oxide (glass) surfaces are easy to modify, it is possible to fabricate reactors that are preloaded with catalysts, Wahl says. And third, the structured surfaces of the MIT system are covered with glass, making it possible to observe reactions as they take place.

The MIT system is not yet available commercially. But when it becomes available, Sigma-Aldrich will be considering it for possible adoption into its business operations, Wahl says. Meanwhile, Sigma-Aldrich will be closely following the further development of MIT’s technology, hoping for a chance to test a prototype.

SOURCE:  http://pubs.acs.org/cen/news/8226/8226earlysci2.html

All Glass Micro-Reactor Created as Lab-On-A-Chip | Kurzweil AI

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riken_glass_lab_on_a_chip

Yo Tanaka from the RIKEN Quantitative Biology Center has developed a reliable and durable system for incorporating glass microfluidics into lab-on-a-chip devices.

Lab-on-a-chip devices are microfluidic cells that incorporate pipes, reaction vessels, valves and a host of other implements typically found in laboratories. These components are typically carved into an inexpensive flat plastic plate, made of polydimethylsiloxane (PDMS), to enable efficient processing of microliter-volume samples.

Plastics, however, have several disadvantages, including degradation when exposed to reactive chemicals and a tendency to adsorb sample molecules before they can be analyzed. They can also interfere with analysis techniques that rely on shining a light through the device due to their imperfect transparency, and are difficult to fabricate due to their fragility.

Glass is an attractive alternative because it is chemically resistant, transparent to light and also capable of withstanding higher fluid pressures than PDMS. Producing flexible and durable glass valves, however, has proved difficult.

To allow glass to be used in these devices, Tanaka developed a Teflon frame to hold an ultrathin sheet of glass so that it could be handled without breaking and incorporated the frame into an all-glass lab-on-a-chip.

Next, Tanaka used hydrogen fluoride to etch channels and chambers into a pair of glass slides, and covered these chambers with ultrathin glass sheets in a way that allowed fluid to be prevented from passing through the chamber by simply pressing down on the glass cover. He then fused the glass sheets together by heating them at 750 °C.

After trying various thicknesses of ultrathin glass sheets, Tanaka found that a 10 micrometer-thick glass film was ideal: strong enough to withstand more than 100 depressions yet able to deform by up to 126 microns — enough to completely close the valve. Tests using water containing small fluorescent polystyrene beads demonstrated that closing the valve using this method blocked fluid flow within 0.12 seconds.

Tanaka now plans to develop his all-glass device for applications such as highly sensitive biochemical analyses and cell studies.

SOURCE:  http://www.kurzweilai.net/an-all-glass-lab-on-a-chip?utm_source=KurzweilAI+Daily+Newsletter&utm_campaign=85e21b4b48-UA-946742-1&utm_medium=email&utm_term=0_6de721fb33-85e21b4b48-282030338

Continuous flow microreactors in nanoparticle synthesis | Syrris

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Although the pharmaceuticals industry has been the main driving force behind the rise of flow chemistry since early 2000, other chemicals-related industries have now taken an interest in this new laboratory technique. For years, organic synthesis has been the main focus of all research work conducted on flow chemistry equipment and the advantages offered by flow chemistry are now well established and documented.1-3 Other fields– such as biofuels, petrochemistry and nanoparticles – can also benefit from these same advantages.

Syrris has seen growing demand for Asia, its latest flow system (pictured below), from companies and universities specialising in nanoparticle synthesis. In addition, there has been an increasing number of publications on the subject of continuous formation of nanoparticles, quantum dots and colloidal metals.

Automated Asia Flow Chemistry System

Nowadays, nanoparticles are used in a wide range of fields because of their physical and chemical properties, resulting in a growing demand that challenges chemists to provide a reliable supply of large amounts of good quality nanoparticles.

Various chemical methods have been applied to produce nanoparticles in batch, but these all present problems: non-homogeneity in mixing, the importance of ageing, the difficulty of accurate temperature control and questionable reproducibility from batch to batch. Often a batch process relies as much on the skill of the chemist as on the chemistry itself.

All of these issues become even more difficult to address when scaling up the manufacturing. Flow chemistry offers a number of advantages that help to overcome these challenges, notably fast and reproducible mixing, excellent temperature control, the ability to carry out pressurised reactions, modularity and easy scale-up.

Accurate reaction control

One of the key characteristics of a flow chemistry system is the very small diameter of its internal wetted channels, which are typically in the range of 0.3-1 mm. This has a huge impact on both the quality of mixing and temperature control in microreactors.

The flow conditions in a system are defined by the Reynolds number (Re), i.e. the mean viscosity of fluid multiplied by characteristic dimension and divided by kinematic viscosity. For a low Reynolds number (below 4,000), flow conditions are laminar; for a high Reynolds number, they are turbulent. In a flow system, the channel dimension results in the Reynolds number always being small (usually <100), therefore flow conditions are always laminar.

Microreactor size (µl) Total flow rate (µl/min) Estimated mixing volume (µl) Estimated mixing time (secs) Residence time (mins)
1 62.5 60 3.3 3.30 1.04
2 62.5 240 6.6 1.65 0.26
3 250 240 12.6 3.15 1.04
4 250 1000 5.6 0.34 0.25
5 250 5000 5.6 0.07 0.05
6 1000 240 19.8 4.95 4.17
7 1000 1000 19.8 1.19 1.00
8 1000 5000 19.8 0.24 0.20

Table. 1 – Phenolphthalein & sodium hydroxide mixing tests

Under laminar flow conditions, mixing is diffusion-limited and extremely fast. Typically, in a Syrris microreactor the mixing is in the order of 1-5 seconds (Table 1). It is also very reproducible, as the shape of the microreactor does not change and no physical stirrer is involved.

Syrris Micromixer

Syrris Micromixer

The mixing time can be reduced even further to below one second, by using specially designed microreactors called micromixer chips (pictured right). This makes the micromixer chip a reactor of choice for nanoparticle synthesis protocols, where mixing is a critical parameter.

The small diameter of the microreactor channels also means that its surface-to-volume ratio is extremely high. This results in excellent heat transfer and fast, efficient temperature control and response. Not only is there no temperature gradient – as seen in a batch reactor – but any exotherm or endotherm is very quickly absorbed, maintaining a homogeneous temperature throughout the microreactor.

Prof. Seeberger and co-workers at the Max Planck Institute of Colloids & Interfaces noted the key role played by precise control over experimental conditions in a paper describing a process for continuous quantum dot synthesis in a glass microreactor.4 The quantum dots synthesised in flow by Seeberger’s group have a much narrower particle distribution than those obtained using a similar batch protocol. This trend has also been shown by Fitzner and co-workers for the preparation of colloidal gold in a flow microreactor.5

More recently, a continuous synthesis protocol for the synthesis of iron nanoparticles has been developed in Syrris’s laboratory. Here, the size of the particle is critical, as it determines its paramagnetic characteristics. Performing the synthesis in microreactors allowed ultra-fast mixing and, subsequently, the formation of fine magnetic iron nanoparticles with better quality and reproducibility than in batch synthesis.6

Process flexibility

Other advantages of using a flow system for making nanoparticles include easy scalability, the modularity of the system and the ability to carry out high pressure reactions and multi-step processes.

A flow chemistry system consisting of a pump, a microreactor and a pressure controller is a good starting point for nanoparticle synthesis. This system will allow the user to run a series of experiments to determine the best reaction conditions. Once the optimised reaction conditions have been established, the same set-up is used to synthesise multi-gram quantities of nanoparticles continuously in suspension.

By adding an autosampler and automating the system via software, the system’s capabilities are expanded and it becomes ideal for process optimisation and the study of reaction parameters. A series of experiments can quickly be set up, run automatically and all the samples collected separately for analysis. Fitzner and co-workers used this kind of set-up to study the effect of reaction temperature on the particle size distribution of colloidal gold.5

Flow chemistry systems are also very easily and safely pressurised using a back pressure regulator. This allows solvents to be heated above their boiling point, which is commonly called ‘superheating’, thus increasing the reaction kinetics and creating ultra-fast reaction conditions. On top of this, pressurising the system minimises any degassing effect that might occur when a reaction produces gas as a by-product.

Finally, microreactors and flow chemistry are ideal for multi-step processes, commonly called ‘telescoping synthesis’. By simply connecting the output of the first reactor to the input of a second, a two-step reaction can be set up. Seeberger’s group used this flow chemistry benefit in their quantum dot process. First, cadmium-selenium nanoparticles were formed in a microreactor, then the nanoparticles were covered with zinc sulphide in a second microreactor connected in series. This two-step reaction was run as one continuous process, therefore saving time and manual effort.4

Conclusion

Flow chemistry is as an effective technology for the optimisation of nanoparticle reactions and their large-scale synthesis. Among the key advantages of flow chemistry which can assist the nanoparticle industry are excellent reaction control, flexibility and easy scale-up. These benefits are of such importance that, in the near future, continuous-flow is likely to become the method of choice for nanoparticle synthesis.

References:

  1. M. Drobot, Speciality Chemicals Magazine 2011, 31(6)
  2. C. Wiles & P. Watts, Green Chemistry 2012, 14, 38-54
  3. L. Malet-Sanz & F. Susanne, J. Med. Chem., forthcoming
  4. P. Laurino, R. Kikkeri & P.H. Seeberger, Nature 2011, 6, 1209-1220
  5. M. Wojnicki, K. Paclawski, M. Lutyblocho, K. Fitzner, P. Oakley & A. Stretton, Rudy I Metale Niezelane 2009, 12
  6. http://www.youtube.com/watch?v=wSMO_Deh9eQ – a video of the experiment

SOURCE:  http://syrris.com/news/news/516-continuous-flow-microreactors-in-nanoparticle-synthesis

Micro-reactors Produce Nanoparticles for Next-Generation Solar | Kurzweil

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solar_cell_nanoparticesEngineers at Oregon State University have determined that ethylene glycol, commonly used in antifreeze products, may be the key to making solar cells that cost less and avoid toxic compounds.

Ethylene glycol functions well in a “continuous flow” reactor — an approach to making thin-film solar cells that is easily scaled up for mass production at industrial levels, they note.

The research, published in Material Letters, a professional journal, also concluded this approach will work with CZTS, or copper zinc tin sulfide, a compound of significant interest for solar cells due to its excellent optical properties and the fact these materials are cheap and environmentally benign.

“The global use of solar energy may be held back if the materials we use to produce solar cells are too expensive or require the use of toxic chemicals in production,” said Greg Herman, an associate professor in the OSU School of Chemical, Biological and Environmental Engineering. “We need technologies that use abundant, inexpensive materials, preferably ones that can be mined in the U.S. This process offers that.”

By contrast, many solar cells today are made with CIGS, or copper indium gallium diselenide. Indium is comparatively rare and costly, and mostly produced in China. Last year, the prices of indium and gallium used in CIGS solar cells were about 275 times higher than the zinc used in CZTS cells.

The technology being developed at OSU uses ethylene glycol in meso-fluidic reactors that can offer precise control of temperature, reaction time, and mass transport to yield better crystalline quality and high uniformity of the nanoparticles that comprise the solar cell — all factors which improve quality control and performance.

This approach is also faster — many companies still use “batch mode” synthesis to produce CIGS nanoparticles, a process that can ultimately take up to a full day, compared to about half an hour with a continuous flow reactor. The additional speed of such reactors will further reduce final costs.

SOURCE:  http://www.kurzweilai.net/antifreeze-cheap-materials-may-lead-to-low-cost-solar-energy/comment-page-1#comment-171287

Microreactors gain popularity among producers | ICIS

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Despite their modest size, microreactors can outperform traditional reactors that are hundreds or thousands of times larger

PRESSED BY margin shrinkage and environmental considerations to streamline costs and reduce environmental damage, many of the biggest names in fine chemicals, specialty chemicals, pharmaceuticals and consumer products are developing applications for microreactors. Some companies are already using them for commercial production.

Microreactors are even being developed for the production of bulk chemicals such as ethylene, methanol, styrene, vinyl acetate monomer (VAM), formaldehyde and ethylene oxide (EO).

It might seem counterintuitive that something called a microreactor could produce 10,000 tonnes/year of a specialty chemical, much less contribute meaningfully to a commodity market, but microreactors are not a batch technology. Because they employ flow chemistry – a continuous process – the principles governing their operation and economics are fundamentally different.

GROWING INTEREST

Like petrochemical plants – the chemical industry’s most intensive users of flow processing – microreactors do chemistry in tubes. But while a typical hydrocracking reactor might have a diameter of 4m, the tubes in microreactors can range between 10 microns and 5mm.

Because reactions in these narrow spaces tend to be extremely fast, the channels, as they are called, are also quite short. Issues related to mixing – heat transfer, mass transfer and hydrodynamics – which slow transformations and allow side reactions in large reactors, are effectively eliminated in microreactors, where mixing is essentially instantaneous, hence the speed. Reaction kinetics become the only factor limiting progress, and rates can increase dramatically.

A growing number of chemical manufacturers are trying to exploit the resulting advantages. They include Switzerland-based Clariant, Sigma Aldrich subsidiary SAFC, Germany’s BASF and Evonik Industries, Netherlands-based DSM, US-based DuPont, and pharmaceutical companies Schering-Plough, Sanofi Aventis, Roche, GlaxoSmithKline, Novartis and Astra Zeneca. Even consumer products giant Procter & Gamble has worked with them.

Dutch fine chemical producer DSM, which has used a microreactor developed by US-based Corning to produce more than 25 tonnes of a nitration product under cGMP conditions in four weeks, will receive a Corning reactor capable of over 100 tonnes of the product annually later this year.

Siegfried, Schering-Plough, PCAS, Isochem and Lonza have also tested technology from Corning, which is developing reactors for “several other major customers,” as well, according to Gary Calabrese, vice president, science and technology at Corning.

Other developers of microreactor technology include Micronit Microfluidics, Future Chemistry, Ehrfeld Mikrotechnik BTS, Uniqsis, Syrris, the Institut fur Mikrotechnik Mainz and Velocys.

The devices supplied by these companies differ in various respects. For example, Corning’s microreactors feature relatively large channels in the millimeter range, which can increase throughput and reduce clogging. They could actually be called millireactors, and indeed the company prefers the term “Advanced Flow” reactor technology.

However, certain advantages are common to all microreactors: improved selectivity and reliability; safety; cost savings; and greater speed to market.

More selective and reliable chemistry results from greater process control. Flow rate, channel length and extremely efficient heat transfer can all be adjusted in micro-reactors to optimize reaction time and temperature. One benefit is less waste, which in turn lowers costs.

“Testing has shown over and over again that energy, processing chemicals and waste are all reduced when using these reactors,” says Calabrese. “In some cases, companies can even eliminate costly purification steps because the products coming out of the Corning reactor are of much higher purity.”

Costs also benefit from greater safety, the result not only of greater process control, but also of small reactor volume, which minimizes the impact of mishaps.

When expensive cryogenic reactors or explosion-proof facilities can be replaced with microreactors, costs are reduced, notes Andreas Weiler, global business director at US-based SAFC, which uses microreactors to produce about 50 commercial products of up to multi-kilogram quantities.

Costs may be further reduced by the smaller footprint, he adds. “Although a sizeable collection vessel will still be required and further work-up and purification procedures are often needed, the space and equipment requirements for the reactors themselves are lower.”

Microreactors also simplify scale up, shortening time to market. Whereas batch processes must often be altered considerably in the transfer to large-scale production, microreactor processes can proceed largely unmodified. Instead, they can be run using multiple microreactors in parallel, a practise called “numbering up.”

“Usually in scale up, modeling is not too predictive,” explains Volker Hessel, head of the department of chemical process technology at the Institut fur Mikrotechnik Mainz (IMM), in Germany. “Here you have very regular flows. You can predict some of the behavior, and you use the same units throughout the development chain – ideally. In practise, this is somewhat different, but it is still a major improvement. You don’t have to reinvent the wheel, as is done now.”

Microreactors often provide a better way to achieve established transformations, but the greater process control and safety also facilitate more difficult or novel chemistries.

“At SAFC, we are finding that continuous microreactors allow us to carry out a number of useful reactions that simply would not be possible in a batch reactor,” says Weiler. “Depending on the process and batch size, they can also be more cost-effective for reactions that already run well in a batch reactor.”

Corning’s Calabrese agrees. “The unique integration of heat control with the reaction layers enables new chemical paths not approachable with traditional batch technology, and the continuous process provides for effective management of unstable intermediates,” he observes.

The IMM’s Hessel, a widely acknowledged authority on microreactor technology, is methodically exploring the expanded range of chemistries possible in microreactors. He employs harsh conditions such as high temperature and pressure to access “novel process windows” in which reaction rates are much higher, even by orders of magnitude.

“We go to the limits to release the true chemical potential,” Hessel explains.

BULKING UP

Most applications being developed for microreactors involve specialty chemicals, fine chemicals and pharmaceuticals, but Velocys, a US-based company recently acquired by UK-based Oxford Catalysts, is focused on bulk chemicals. Among its partners are US-based Dow Chemical Company and Japan-based Toyo Engineering.

“Most microreactor companies offer small-scale microreactors without catalysts that process liquid phase flow,” explains Laura J Silva, director, IP and licensing, at Velocys and Oxford Catalysts. “In contrast, Velocys microchannel reactors can incorporate heterogeneous catalysts or sorbents, and can process large amounts of material at a wide range of temperatures, including high temperatures, and a wide range of pressures, including high pressures.”

Applications of Velocys’ technology include ethylene via the oxidative dehydrogenation of ethane; dimethylether (DME) directly from syngas; the Fischer-Tropsch (FT) process; steam methane reforming; hydrocracking; higher alcohols from syngas; and the production of methanol, styrene, vinyl acetate monomer, formaldehyde and ethylene oxide.

Although microreactors will not replace the large petrochemical complexes that are the chemical industry’s most intensive users of flow chemistry, there are circumstances where the size and portability of microreactors are more beneficial than economies of scale. For example, it is not cost-effective to transport biomass long distances for conversion to fuel, hence Velocys’ biomass-to-liquids (BTL) project.

Last year, Velocys demonstrated a two-gallon-per-day BTL microreactor using a new, highly active FT catalyst developed by Oxford Catalysts. The device operated for more than 3,000 hours and achieved productivities of over 1,500 kg/m3/h. Standard fixed bed FT reactors typically operate at productivities of around 100 kg/m3/h, Silva notes, and slurry bed FT reactors at around 200 kg/m3/h. A larger-scale demonstration of the BTL process will take place later this year at the Wright-Patterson Air Force base in Dayton, Ohio, US.

The same principle lies behind the company’s offshore gas-to-liquids project, which targets stranded gas. In the case of materials such as ethylene oxide, on the other hand, the problem is the transportation of the product, and the solution is in situ generation at small scale.

Challenges do remain on the path to widespread adoption of microreactor technology, says Harmen Lelivelt, sales engineer at Netherlands-based Micronit Microfluidics. They include the integration of online control, the integration of separation steps, solids handling and the cost of large microreactors. Whereas a complete lab unit might cost from €10,000-70,000 ($13,000-90,000), a dedicated production plant runs from €100,000-500,000, he says.

However, microreactor technology clearly has momentum. IMM’s Hessel says it may be another 10 years before microreactors are considered a regular tool, but he expects a fifth of processors to employ them. Corning’s Calabrese believes that as much as 30% of the fine chemicals and drugs currently in production could be made more efficiently using microreactors.

Lelivelt anticipates growing interest among R&D groups and gradual acceptance and implementation by industry. “It will be an important [tool],” he says, “one that will certainly claim its place in chemical technology.”

SOURCE:  http://www.icis.com/Articles/2009/05/04/9211877/microreactors+gain+popularity+among+producers.html

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