12 research outputs found

    Gas–liquid dynamics at low Reynolds numbers in pillared rectangular micro channels

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    Most heterogeneously catalyzed gas–liquid reactions in micro channels are chemically/kinetically limited because of the high gas–liquid and liquid–solid mass transfer rates that can be achieved. This motivates the design of systems with a larger surface area, which can be expected to offer higher reaction rates per unit volume of reactor. This increase in surface area can be realized by using structured micro channels. In this work, rectangular micro channels containing round pillars of 3 μm in diameter and 50 μm in height are studied. The flow regimes, gas hold-up, and pressure drop are determined for pillar pitches of 7, 12, 17, and 27 μm. Flow maps are presented and compared with flow maps of rectangular and round micro channels without pillars. The Armand correlation predicts the gas hold-up in the pillared micro channel within 3% error. Three models are derived which give the single-phase and the two-phase pressure drop as a function of the gas and liquid superficial velocities and the pillar pitches. For a pillar pitch of 27 μm, the Darcy-Brinkman equation predicts the single-phase pressure drop within 2% error. For pillar pitches of 7, 12, and 17 μm, the Blake-Kozeny equation predicts the single-phase pressure drop within 20%. The two-phase pressure drop model predicts the experimental data within 30% error for channels containing pillars with a pitch of 17 μm, whereas the Lockhart–Martinelli correlation is proven to be non-applicable for the system used in this work. The open structure and the higher production rate per unit of reactor volume make the pillared micro channel an efficient system for performing heterogeneously catalyzed gas–liquid reaction

    A 'plug & play' microreactor for rapid screening of the activity of a catalyst on different supports

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    A ‘plug & play’ micro reactor is demonstrated for the rapid screening of the activity of a heterogeneous catalyst on different types of supports. The micro reactor can hold three interchangeable plates with each the same catalyst support. As a proof-of-principle, the hydrogenation of 3-methyl-1-pentyn-3-ol over a Pd catalyst has been performed over three different supports, viz., flat plates, washcoated plates and plates covered with carbon nano fibres. The flat plate support shows (partly) kinetically limited reaction rates, where carbon nano fibres do not run into these limitations, due to the larger surface area available for catalyst deposition

    A 'plug & play' microreactor for rapid screening of the activity of a catalyst on different supports

    No full text
    A ‘plug & play’ micro reactor is demonstrated for the rapid screening of the activity of a heterogeneous catalyst on different types of supports. The micro reactor can hold three interchangeable plates with each the same catalyst support. As a proof-of-principle, the hydrogenation of 3-methyl-1-pentyn-3-ol over a Pd catalyst has been performed over three different supports, viz., flat plates, washcoated plates and plates covered with carbon nano fibres. The flat plate support shows (partly) kinetically limited reaction rates, where carbon nano fibres do not run into these limitations, due to the larger surface area available for catalyst deposition

    Enhanced liquid-solid mass transfer in micro channels by a layer of carbon nano fibers

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    This paper demonstrates that the observed rate of reaction of the liquid-phase selective hydrogenation of an alkyne is higher for an open and rough carbon nanofiber (CNF) layer positioned on a microchannel wall than for an unsupported flat plate catalyst or dense and smooth CNF layers. This enhancement can be contributed to two phenomena: (1) the kinetic reaction rate increases with a factor of 1.4, due to an increase of the open and freely accessible surface area of the CNF layer available for catalyst deposition; (2) the liquid–solid mass transfer increases with a factor of 2.8, due to an increase in the surface roughness of the CNF layer and the formation of large spherical islands of clustered CNFs. A thin layer of CNFs on a microchannel wall can therefore successfully be used to increase the overall rate of reaction per reactor volume compared to an unsupported flat plate catalyst

    A 'plug & play' microreactor for rapid screening of the activity of a catalyst on different supports

    No full text
    A ‘plug & play’ micro reactor is demonstrated for the rapid screening of the activity of a heterogeneous catalyst on different types of supports. The micro reactor can hold three interchangeable plates with each the same catalyst support. As a proof-of-principle, the hydrogenation of 3-methyl-1-pentyn-3-ol over a Pd catalyst has been performed over three different supports, viz., flat plates, washcoated plates and plates covered with carbon nano fibres. The flat plate support shows (partly) kinetically limited reaction rates, where carbon nano fibres do not run into these limitations, due to the larger surface area available for catalyst deposition
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