Managing Solids in Microreactors for the Upstream Continuous Processing of Fine Chemicals

Hartman, Ryan L.

doi:10.1021/op200348t

Cited by 237 publications

(190 citation statements)

References 191 publications

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“…Hydrodynamic failure is one of the main obstacles for the continuous flow synthesis involving solid reactants and/or products. Continuous production having a high solid content is susceptible to hydrodynamic failure caused by constriction, bridging, and random detachment of solid particles (23). In our case, the solid content in the synthesis mixture was significantly high even in the presence of pressurized hot water.…”

Section: Significancementioning

confidence: 63%

Continuous flow synthesis of ZSM-5 zeolite on the order of seconds

Liu

Okabe

Anand

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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The hydrothermal synthesis of zeolites carried out in batch reactors takes a time so long (typically, on the order of days) that the crystallization of zeolites has long been believed to be very slow in nature. We herein present a synthetic process for ZSM-5, an industrially important zeolite, on the order of seconds in a continuous flow reactor using pressurized hot water as a heating medium. Direct mixing of a well-tuned precursor (90°C) with the pressurized water preheated to extremely high temperature (370°C) in the millimeter-sized continuous flow reactor resulted in immediate heating to high temperatures (240-300°C); consequently, the crystallization of ZSM-5 in a seed-free system proceeded to completion within tens of or even several seconds. These results indicate that the crystallization of zeolites can complete in a period on the order of seconds. The subtle design combining a continuous flow reactor with pressurized hot water can greatly facilitate the mass production of zeolites in the future. Z eolites have typically been synthesized via hydrothermal treatment, a process designed to artificially mimic the geological formation conditions of natural zeolites (1, 2). Depending on the targeted framework and composition, several hours to days (or even several weeks) are required to complete the synthesis of a crystalline product (3). As a great improvement over the hundreds or thousands of years required for the formation of natural zeolites, artificial synthesis on the order of days allows us more opportunities to obtain zeolites with tunable properties (4, 5). Nevertheless, the hydrothermal synthesis of zeolites has remained a time-consuming process. Long periods of hydrothermal treatment, for one thing, cause a burden on both energy efficiency and operational costs. Furthermore, pressure-tight vessels used for the hydrothermal treatment as well as harsh conditions therein make mechanistic studies using in situ techniques difficult to perform (6, 7). The complexity of crystallization, in turn, hinders the attempts at shortening the synthesis period. This dilemma explains to some extent the reason behind the long-held belief that crystallization of zeolites is extremely slow in nature.The other major hurdle for the widespread application of zeolites is the difficulty in mass production. Batchwise synthesis using autoclaves is convenient for basic laboratory investigations but poses several challenges--in terms of economic efficiency, quality control, and operation flexibility--when large-scale manufacturing is considered (8). In contrast, continuous flow process has proved to be beneficial in the production of various chemicals (9, 10). Due to the time-consuming hydrothermal treatment used for the synthesis of zeolites, however, making a direct switch from batchwise synthesis to continuous flow manufacturing is not easy. To realize continuous flow production, shortening the synthesis period is therefore an issue of the highest priority. Recently, we have developed an ultrafast route to synthesize indust...

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Section: Significancementioning

confidence: 63%

Continuous flow synthesis of ZSM-5 zeolite on the order of seconds

Liu

Okabe

Anand

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…In recent years, a lot of progress has been made to overcome the hurdles of microreactor clogging. 16 …”

Section: Logistics/qualitymentioning

confidence: 99%

“…16,155,156 Solid materials can aggregate or deposit on the reactor walls, which leads to channel blockage and prevents fluid from flowing. The presence of solids in a reaction stream can have several origins, including solid starting materials and generation of precipitation during the reactions by forming insoluble products or by-products.…”

Section: Solids Handling In Flowmentioning

confidence: 99%

Beyond Organometallic Flow Chemistry: The Principles Behind the Use of Continuous-Flow Reactors for Synthesis

Noël

Hessel

2015

Topics in Organometallic Chemistry

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Flow chemistry is typically used to enable challenging reactions which are difficult to carry out in conventional batch equipment. Consequently, the use of continuous-flow reactors for applications in organometallic and organic chemistry has witnessed a spectacular increase in interest from the chemistry community in the last decade. However, flow chemistry is more than just pumping reagents through a capillary and the engineering behind the observed phenomena can help to exploit the technology's full potential. Here, we give an overview of the most important engineering aspects associated with flow chemistry. This includes a discussion of mass-, heat-, and photon-transport phenomena which are relevant to carry out chemical reactions in a microreactor. Next, determination of intrinsic kinetics, automation of chemical processes, solids handling and multistep reaction sequences in flow are discussed. Safety is one of the main drivers to implement continuous-flow microreactor technology in an existing process and a brief overview is given here as well. Finally, the scale-up potential of microreactor technology is reviewed.

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“…The synthetic methodologies applied in the preparation of pharmaceuticals and fine chemicals commonly involve solids in the form of reagents, catalysts, inorganic by-products, and organic products [62,63]. The coupling of aromatic molecules to prepare useful intermediates and final products presents virtually unlimited pathways and methodologies that involve the use of solids.…”

Section: Particles Encountered In Microreactorsmentioning

confidence: 99%

Particle Handling Techniques in Microchemical Processes

Flowers

Hartman

2012

Challenges

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Abstract:The manipulation of particulates in microfluidics is a challenge that continues to impact applications ranging from fine chemicals manufacturing to the materials and the life sciences. Heterogeneous operations carried out in microreactors involve high surface-to-volume characteristics that minimize the heat and mass transport resistances, offering precise control of the reaction conditions. Considerable advances have been made towards the engineering of techniques that control particles in microscale laminar flow, yet there remain tremendous opportunities for improvements in the area of chemical processing. Strategies that have been developed to successfully advance systems involving heterogeneous materials are reviewed and an outlook provided in the context of the challenges of continuous flow fine chemical processes.

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Managing Solids in Microreactors for the Upstream Continuous Processing of Fine Chemicals

Cited by 237 publications

References 191 publications

Continuous flow synthesis of ZSM-5 zeolite on the order of seconds

Continuous flow synthesis of ZSM-5 zeolite on the order of seconds

Beyond Organometallic Flow Chemistry: The Principles Behind the Use of Continuous-Flow Reactors for Synthesis

Particle Handling Techniques in Microchemical Processes

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