Microcapillary film reactor outperforms single-bore mesocapillary reactors in continuous flow chemical reactions
| Autor: | Kirandeep K. Gill, Patrick Hester, Rachel Gibson, Kam Ho Chester Yiu, Nuno M. Reis |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
Chemistry(all)
Capillary action General Chemical Engineering 02 engineering and technology 010402 general chemistry 01 natural sciences Industrial and Manufacturing Engineering symbols.namesake Environmental Chemistry Microcapillary Film Reactor New dimensionless number Flow chemistry Residence time distribution Molecular diffusion Plug flow Continuous reactor Tubular microreactors Reynolds number General Chemistry Mechanics 021001 nanoscience & nanotechnology Continuous manufacturing 0104 chemical sciences Volumetric flow rate Chemical Engineering(all) symbols 0210 nano-technology |
| Zdroj: | Gill, K K, Gibson, R, Yiu, K H C, Hester, P & Reis, N M 2021, ' Microcapillary film reactor outperforms single-bore mesocapillary reactors in continuous flow chemical reactions ', Chemical Engineering Journal, vol. 408, 127860 . https://doi.org/10.1016/j.cej.2020.127860 |
| ISSN: | 1385-8947 |
| DOI: | 10.1016/j.cej.2020.127860 |
| Popis: | Meso- and micro-flow reactors are routinely used in continuous flow chemistry, however the role of capillary diameter, D, on conversion and reaction rates is often overlooked during scale-up. Volume, pressured drop and diffusion distances/times must be delicately balanced to fully realize the hydrodynamic capabilities of continuous chemical flow reactors. We carried out a comprehensive Computational Fluid Dynamics analysis experimentally validated with detailed fluid tracing, residence time distributions and continuous chemical reactions (neutralization and 4th Bourne reaction) to fully elucidate the role of D and molecular diffusion in reagents dispersion and chemical conversion. To our understanding, we captured and reported both numerically and experimentally for the first time the transition from convective, segregated flow to plug flow and dispersed flow, which we propose is linked to a dimensionless ratio between the time scales of diffusion to convection, tdiff/tconv. We tested three tubular systems: a small-bore (i.d. ~1100 µm) and large-bore (i.d. ~2400 µm) capillary reactor and a novel multiplexed (10-bore) Microcapillary Film Reactor (MFR) with mean i.d. 363 ± 32.2 µm. In the MFR's narrow microcapillaries we observed excellent radial diffusion linked to the small diffusion distance, with low dimensionless axial dispersion coefficient values (Dax/uL) ranging from 0.0015 ± 0.0005 to 0.0033 ± 0.0006 (for flow rates 0.5–5.0 mL/min), exhibiting all the desired features of a high-performance ‘plug’ flow system. Dax/uL remained mostly independent of the Reynolds number, whereas for the single, large bore capillary the Dax/uL values (0.032–0.057) increased linearly with the Reynolds numbers (19.4–48.5), shifting towards very dispersive flow. We propose splitting flow through multiple parallel microcapillaries as in the MFR is a superior strategy for scaling-up continuous flow reactions compared to increasing D, which neglects diffusive effects. |
| Databáze: | OpenAIRE |
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