Performance of the monolithic stirrer reactor: applicability in multi-phase processes

Hoek, Ingrid; Nijhuis, T.A.; Stankiewicz, AI; Moulijn, Jacob A.

doi:10.1016/j.ces.2004.07.077

Cited by 40 publications

(27 citation statements)

References 12 publications

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“…An interesting alternative for the MLR in terms of pH control could be the monolithic stirrer reactor (MSR), in which monoliths are used as stirrer blades. This reactor has been successfully applied for different applications [ 27 , 28 ], including enzymatic reactions [ 29 ].…”

Section: Discussionmentioning

confidence: 99%

Hydrogel coated monoliths for enzymatic hydrolysis of penicillin G

Lathouder

Smeltink

Straathof

et al. 2008

J Ind Microbiol Biotechnol

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The objective of this work was to develop a hydrogel-coated monolith for the entrapment of penicillin G acylase (E. coli, PGA). After screening of different hydrogels, chitosan was chosen as the carrier material for the preparation of monolithic biocatalysts. This protocol leads to active immobilized biocatalysts for the enzymatic hydrolysis of penicillin G (PenG). The monolithic biocatalyst was tested in a monolith loop reactor (MLR) and compared with conventional reactor systems using free PGA, and a commercially available immobilized PGA. The optimal immobilization protocol was found to be 5 g l−1 PGA, 1% chitosan, 1.1% glutaraldehyde and pH 7. Final PGA loading on glass plates was 29 mg ml−1 gel. For 400 cpsi monoliths, the final PGA loading on functionalized monoliths was 36 mg ml−1 gel. The observed volumetric reaction rate in the MLR was 0.79 mol s−1 m−3monolith. Apart from an initial drop in activity due to wash out of PGA at higher ionic strength, no decrease in activity was observed after five subsequent activity test runs. The storage stability of the biocatalysts is at least a month without loss of activity. Although the monolithic biocatalyst as used in the MLR is still outperformed by the current industrial catalyst (immobilized preparation of PGA, 4.5 mol s−1 m−3catalyst), the rate per gel volume is slightly higher for monolithic catalysts. Good activity and improved mechanical strength make the monolithic bioreactor an interesting alternative that deserves further investigation for this application. Although moderate internal diffusion limitations have been observed inside the gel beads and in the gel layer on the monolith channel, this is not the main reason for the large differences in reactor performance that were observed. The pH drop over the reactor as a result of the chosen method for pH control results in a decreased performance of both the MLR and the packed bed reactor compared to the batch system. A different reactor configuration including an optimal pH profile is required to increase the reactor performance. The monolithic stirrer reactor would be an interesting alternative to improve the performance of the monolith-PGA combination.

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Section: Discussionmentioning

confidence: 99%

Hydrogel coated monoliths for enzymatic hydrolysis of penicillin G

Lathouder

Smeltink

Straathof

et al. 2008

J Ind Microbiol Biotechnol

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“…These studies demonstrate the potential of the catalytic stirrer reactors over the conventional slurry reactors not only due to the obvious operational advantages such as no need of catalyst recovery, prevent attrition of the catalyst, lower pressure drops and intrinsically safer operations, but also because MSR improves the conversions and selectivity as a result of the faster gas-liquid mass transfer rates induced by the stirring [5,8] and the larger geometrical surface areas available for the catalysis. Moreover, the gas-liquid mass transfer rates can be modulated according to the disposition of the monoliths in the shaft and the length of the monoliths [5,9]. More recently, MSRs have been demonstrated to be a suitable alternative for the intensification of selective oxidation of hydrocarbons, i.e., dihydroxybenzene production over Fe/SiC by phenol hydroxylation with H 2 O 2 [10] and lactobionic acid production over gold catalyst by lactose oxidation by O 2 [11], and for liquid-liquid catalytic reactions such as the alcoholysis of urea to propylene carbonate over different mixed-metal oxides [12].…”

Section: Introductionmentioning

confidence: 79%

“…Attending to the rate equations constituting the kinetic model (Equations ( 1)-( 4)), it is proposed that the phenol hydroxylation by H 2 O 2 over 3D 1 wt.% Fe/Al 2 O 3 monoliths takes place as follows: first, H 2 O 2 is adsorbed on the Fe active sites, Equation (5). Then, the adsorbed molecule of H 2 O 2 needs a neighboring free catalytic site that interacts with phenol.…”

Section: Reaction Mechanismmentioning

confidence: 99%

“…The concept was demonstrated by an aqueous phase reaction, the decomposition of hydrogen peroxide (H 2 O 2 ) over manganese oxide catalyst [3] and has since then been extended to multiphase processes (gas-liquid phase reactions) such as the selective hydrogenation of alkyne [3][4][5] and more viscous systems such as the hydrogenation of edible oil over palladium catalysts [6] and the enzyme-catalyzed reactions in organic media [7]. These studies demonstrate the potential of the catalytic stirrer reactors over the conventional slurry reactors not only due to the obvious operational advantages such as no need of catalyst recovery, prevent attrition of the catalyst, lower pressure drops and intrinsically safer operations, but also because MSR improves the conversions and selectivity as a result of the faster gas-liquid mass transfer rates induced by the stirring [5,8] and the larger geometrical surface areas available for the catalysis. Moreover, the gas-liquid mass transfer rates can be modulated according to the disposition of the monoliths in the shaft and the length of the monoliths [5,9].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Monolithic Stirrer Reactors for the Sustainable Production of Dihydroxybenzenes over 3D Printed Fe/γ-Al2O3 Monoliths: Kinetic Modeling and CFD Simulation

et al. 2022

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The aim of this work is to evaluate the performance of the stirring 3D Fe/Al2O3 monolithic reactor in batch operation applied to the liquid-phase hydroxylation of phenol by hydrogen peroxide (H2O2). An experimental and numerical investigation was carried out at the following operating conditions: CPHENOL,0 = 0.33 M, CH2O2,0 = 0.33 M, T = 75–95 °C, P = 1 atm, ω = 200–500 rpm and WCAT ~ 1.1 g. The kinetic model described the consumption of the H2O2 by a zero-order power-law equation, while the phenol hydroxylation and catechol and hydroquinone production by Eley–Rideal model; the rate determining step was the reaction between the adsorbed H2O2, phenol in solution with two active sites involved. The 3D CFD model, coupling the conservation of mass, momentum and species together with the reaction kinetic equations, was experimentally validated. It demonstrated a laminar flow characterized by the presence of an annular zone located inside and surrounding the monoliths (u = 40–80 mm s−1) and a central vortex with very low velocities (u = 3.5–8 mm s−1). The simulation study showed the increasing phenol selectivity to dihydroxybenzenes by the reaction temperature, while the initial H2O2 concentration mainly affects the phenol conversion.

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“…The former is a stirring vessel in which the catalyst is shown in small‐sized powder form to maximize the contact area and minimize the intra‐particle diffusion distances but results in inconvenient recovery and separation from the reaction system. Stirring serves three functions: preventing catalysts from settling, speeding up the interphase diffusion, and minimizing concentration gradients 8,9 . In the fixed‐bed reactor, the catalyst is usually in granular form, and the flow is driven by gravity or external feed pressure.…”

Section: Introductionmentioning

confidence: 99%

Three‐dimensional‐printed holistic reactors with fractal structure for heterogeneous reaction

Sun

Wang

et al. 2021

AIChE Journal

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Holistic catalytic reactors with fractal structures have attracted growing attention in heterogeneous reactions because of their advantages of improved mass transfer and easy separation. Herein, a cost‐efficient and straightforward design strategy that combined three‐dimensional printing and electroless deposition was presented to construct dynamic, holistic stirred reactors with the fractal structure. The conversion factor α of the fractal impeller is 65.01 mmol m−2 h−1 with a large volume of reactant (80 ml), which is 1.7 times that of the normal impeller with the same loading of Ag catalysts. Experimental results and simulation analysis demonstrate that the fractal impeller significantly improves the catalytic performance by enhancing mass transfer and spatial dispersion in the reaction. Moreover, the holistic impeller could be reused 10 times without obvious loss of catalytic performance, and easily separated from the reaction system. The structural design of fractal reactors will open the way for high‐efficiency dynamic heterogeneous catalytic reactors.

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Performance of the monolithic stirrer reactor: applicability in multi-phase processes

Cited by 40 publications

References 12 publications

Hydrogel coated monoliths for enzymatic hydrolysis of penicillin G

Hydrogel coated monoliths for enzymatic hydrolysis of penicillin G

Monolithic Stirrer Reactors for the Sustainable Production of Dihydroxybenzenes over 3D Printed Fe/γ-Al2O3 Monoliths: Kinetic Modeling and CFD Simulation

Three‐dimensional‐printed holistic reactors with fractal structure for heterogeneous reaction

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