Analysis of remote detection travel time curves measured from microfluidic channels

Telkki, Ville‐Veikko; Живонитко, Владимир В.

doi:10.1016/j.jmr.2011.03.011

Cited by 14 publications

(6 citation statements)

References 40 publications

(54 reference statements)

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“…[25,26] It is an on-invasive method to obtain versatile spatial, spectral, and dynamic information from am icrofluidic device without the need for optical transparency or additional tracer molecules. [36][37][38][39][40][41][42] In this work, the yield of the hydrogenation reaction in the microfluidic chips was determined from 1 HNMR spectra measured by an ultrasensitive microsolenoidw ound around an outlet capillaryw hile the gas mixture was flowing out from the reactor.F urthermore, remote detection (RD) NMR [43,44] was utilized for visualization of the gas flow in the reactors. The sensitivity problem is especially difficult when low density gaseous fluids are investigated.…”

Section: Introductionmentioning

confidence: 99%

Efficient Catalytic Microreactors with Atomic‐Layer‐Deposited Platinum Nanoparticles on Oxide Support

Rontu

Selent

Живонитко

et al. 2017

Chemistry A European J

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Microreactors attract a significant interest for chemical synthesis due to the benefits of small scales such as high surface to volume ratio, rapid thermal ramping, and well-understood laminar flows. The suitability of atomic layer deposition for application of both the nanoparticle catalyst and the support material on the surfaces of channels of microfabricated silicon microreactors is demonstrated in this research. Continuous-flow hydrogenation of propene into propane at low temperatures with TiO -supported catalytic Pt nanoparticles was used as a model reaction. Reaction yield and mass transport were monitored by high-sensitivity microcoil NMR spectroscopy as well as time-of-flight remote detection NMR imaging. The microreactors were shown to be very efficient in propene conversion into propane. The yield of 100 % was achieved at 50 °C with a reactor decorated with Pt nanoparticles of average size of roughly 1 nm and surface coverage of 3.2 % in 20 mm long reaction channels with a residence time of 1100 ms. The activity of the Pt catalyst surfaces was on the order of several to tens of mmol s m .

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Section: Introductionmentioning

confidence: 99%

Efficient Catalytic Microreactors with Atomic‐Layer‐Deposited Platinum Nanoparticles on Oxide Support

Rontu

Selent

Живонитко

et al. 2017

Chemistry A European J

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“…Overall, the combined sensitivity gain provided by the RD scheme and PHIP was 48 000‐fold, and the experiments turned out to be one to two orders of magnitude more sensitive than the corresponding RD experiments with HP Xe. Comparison of the TOF images of a gas and a liquid (Figures b,c) nicely depicts different flow behavior of these phases; laminar flow of a liquid translates the encoded liquid molecules over a large distance (Figure c), whereas for a gas the three orders of magnitude faster diffusion causes efficient mixing of the flow lamellas, leading to a significantly less dispersed, plug‐like flow behavior (Figure b) ,…”

Section: Remote‐detection Mri Of Hyperpolarized Gasesmentioning

confidence: 93%

NMR Hyperpolarization Techniques of Gases

Barskiy

Coffey

Nikolaou

et al. 2016

Chemistry A European J

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Nuclear spin polarization can be significantly increased through the process of hyperpolarization, leading to an increase in the sensitivity of nuclear magnetic resonance (NMR) experiments by 4–8 orders of magnitude. Hyperpolarized gases, unlike liquids and solids, can be more readily separated and purified from the compounds used to mediate the hyperpolarization processes. These pure hyperpolarized gases enabled many novel MRI applications including the visualization of void spaces, imaging of lung function, and remote detection. Additionally, hyperpolarized gases can be dissolved in liquids and can be used as sensitive molecular probes and reporters. This mini-review covers the fundamentals of the preparation of hyperpolarized gases and focuses on selected applications of interest to biomedicine and materials science.

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“…RD NMR has been used for profiling flow and mixing of fluids in microfluidic devices. 25,26,[28][29][30][31][32][33][34][35] Recently, we demonstrated that the combination of RD NMR and the parahydrogen-induced polarization (PHIP) technique is a versatile tool for characterization of microfluidic packed-bed reactors. 36 In this work, we utilize, for the first time, RD NMR for imaging a chemical reaction in microfluidic chips.…”

Section: Introductionmentioning

confidence: 99%

Remote detection NMR imaging of gas phase hydrogenation in microfluidic chips

et al. 2013

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The heterogeneous hydrogenation reaction of propene into propane in microreactors is studied by remote detection (RD) nuclear magnetic resonance (NMR). The reactors consist of 36 parallel microchannels (50 × 50 μm(2) cross sections) coated with a platinum catalyst. We show that RD NMR is capable of monitoring reactions with sub-millimeter spatial resolution over a field-of-view of 30 × 8 mm(2) with a steady-state time-of-flight time resolution in the tens of milliseconds range. The method enables the visualization of active zones in the reactors, and time-of-flight is used to image the flow velocity variations inside the reactor. The overall reaction yields determined by NMR varied from 10% to 50%, depending on the flow rate, temperature and length of the reaction channels. The reaction yield was highest for the channels with the lowest flow velocity. Propane T1 relaxation time in the channels, estimated by means of RD NMR images, was 270 ± 18 ms. No parahydrogen-induced polarization (PHIP) was observed in experiments carried out using parahydrogen-enriched H2, indicating fast spreading of the hydrogen atoms on the sputtered Pt surface. In spite of the low concentration of gases, RD NMR made imaging of gas phase hydrogenation of propene in microreactors feasible, and it is a highly versatile method for characterizing on-chip chemical reactions.

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Analysis of remote detection travel time curves measured from microfluidic channels

Cited by 14 publications

References 40 publications

Efficient Catalytic Microreactors with Atomic‐Layer‐Deposited Platinum Nanoparticles on Oxide Support

Efficient Catalytic Microreactors with Atomic‐Layer‐Deposited Platinum Nanoparticles on Oxide Support

NMR Hyperpolarization Techniques of Gases

Remote detection NMR imaging of gas phase hydrogenation in microfluidic chips

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