Selectivity, Hydrodynamics and Solvent Effects in a Monolith Cocurrent Downflow Contactor (CDC) Reactor

Winterbottoma, Mike; Marwan, H.; Natividad, Reyna

doi:10.1002/cjce.5450810367

Cited by 17 publications

(6 citation statements)

References 15 publications

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“…This result is significant because it demonstrates there is a clear advantage in using a structured catalyst with alternating gas‐ and liquid‐rich conditions at the surface. Selectivity enhancements have also been found previously for catalyst monoliths operated in slug flow when applied to low MW hydrogenations 30, 31. These enhancements are presumed to arise from more uniform residence times on the catalyst surface (for the polymer) and more plug flow‐like behavior.…”

Section: Resultssupporting

confidence: 65%

Polymer hydrogenation in pulsed flow systems with extrusion

Bussard

Dooley

2008

AIChE Journal

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in Wiley InterScience (www.interscience.wiley.com).The hydrogenation of poly(styrene) over a Pd/Al 2 O 3 catalyst was studied in reactors where pulsed flows are present due to both extrusion and forced pulsing. The reaction was investigated over a range of flow rates, polymer concentrations, and pulsing conditions. Observed activities were highly related to gas-to-liquid mass transfer rates predicted by a correlation for slug flow in catalyst monoliths. A reactor fed by a liquid-starved extruder is an attractive choice for hydrogenation at low polymer concentrations, where intrinsic reaction rates are approached. Higher polymer concentrations (10 wt %) lead to higher mass transfer resistances and a decrease in observed activity. But in this case forced pulsing has a greater effect on productivity; an optimum pulsing frequency was observed. Selectivity was higher and power input lower than in a stirred tank at comparable conditions. The optimal frequency is higher than those found in previous work on hydrogenations.

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Section: Resultssupporting

confidence: 65%

Polymer hydrogenation in pulsed flow systems with extrusion

Bussard

Dooley

2008

AIChE Journal

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“…The dependence of propene oxide concentration on the operating pressure was nearly linear. In the literature, the same trend was observed in some multiphase hydrogenation reactions in monolith reactors [59,60,61,62,63]. Such linear dependences were explained by the fact that the solubility of gas is directly proportional to pressure according to Henry's law.…”

Section: Propene Epoxidation In Monolith and Ctf Reactor At High Pressupporting

confidence: 66%

Comparison of a monolith and a confined Taylor flow (CTF) reactor for propene epoxidation

Shin

Chadwick

2018

Chemical Engineering and Processing - Process Intensification

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Heterogeneous catalytic epoxidation of propene to propene oxide with hydrogen peroxide was investigated in a monolith and a confined Taylor flow (CTF) reactor in which titanium silicalite (TS-1) catalyst was coated on the walls. The influence of gas and liquid superficial velocity on the hydrodynamic characteristics of the monolith and CTF reactor was also investigated under Taylor flow regime at atmospheric and high pressure. The reactors showed distinctly different hydrodynamic properties which in turn led to different performance for propene epoxidation. The production rate of propene oxide was higher in the monolith reactor due to its larger catalyst coating area, larger mass-transfer surface area and more frequent recycling of liquid flow. A variation of reactor column structures confirmed that the propene oxide production was highly dependent on the catalyst coating area and cross-sectional area of the reactor column. High operating pressure made a significant impact on the length of Taylor bubbles and the propene oxide production rate was found to increase in proportion to the operating pressure.

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“…The above studies give insights as to the behavior of the trickle bed reactor; experiments being carried out in batch recycle mode, as is the case for many previous investigations of this type. − Transfer of the process to truly continuous processing is more challenging owing to the possibly low conversions that occur in a single pass through the reactor. However, continuous operation has been tested in this work.…”

Section: Resultsmentioning

confidence: 99%

Selective Hydrogenation of 1-Heptyne in a Mini Trickle Bed Reactor

Al-Herz

Simmons

Wood

2011

Ind. Eng. Chem. Res.

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The selective hydrogenation of 1-heptyne over a 2 wt % Pd/Al2O3 catalyst was studied in a trickle bed reactor operating in both batch recycle and continuous modes. The reaction was studied in a range of different solvents, including isopropanol, hexane, mixtures of these two solvents, and also isopropanol with small quantities of water and base (NaOH) added. It was found that the rate of reaction was fastest in hexane, owing to the higher hydrogen solubility in this solvent. However, the selectivity toward 1-heptene was higher in isopropanol, with over 95% selectivity being maintained for 120 min of the total 240 min reaction time. The addition of water or base led to an increase in reaction rate, possibly through modification of the adsorption equilibria at the catalyst surface or direct involvement in the reaction. The hydrodynamics of trickle flow upon the reaction were investigated, showing that increasing liquid flow rate led to enhancement of reaction rate, although a plateau was eventually reached at the higher flows. The higher flows led to improved catalyst wetting, liquid hold up, and mass transfer rates, thus explaining the enhanced reaction rate. The concentration profiles were fitted according to a Langmuir–Hinshelwood kinetic expression. Operation in continuous flow was demonstrated, although a long residence time was required for high conversion, leading to lower 1-heptene selectivity compared with batch recycle operation.

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Selectivity, Hydrodynamics and Solvent Effects in a Monolith Cocurrent Downflow Contactor (CDC) Reactor

Cited by 17 publications

References 15 publications

Polymer hydrogenation in pulsed flow systems with extrusion

Polymer hydrogenation in pulsed flow systems with extrusion

Comparison of a monolith and a confined Taylor flow (CTF) reactor for propene epoxidation

Selective Hydrogenation of 1-Heptyne in a Mini Trickle Bed Reactor

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