Gas‐phase reaction in a trickle‐bed reactor operated at low liquid flow rates

Castellari, A. T.; Cechini, J. O.; Gabarain, Leonardo; Haure, Patricia M.

doi:10.1002/aic.690430716

Cited by 11 publications

(5 citation statements)

References 16 publications

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“…Consequently, the overall rate of the reaction decreases even though the liquid−solid mass-transfer coefficient increases . This has been experimentally reported in several publications. ,,, …”

Section: Resultssupporting

confidence: 57%

“…Most laboratory kinetic experiments in studies of trickle-bed reactors have been conducted after prewetting of the bed. This reduces the time required to achieve steady state, reduces catalyst deactivation, minimizes side reactions, and improves reproducibility. ,− Different prewetting procedures have been reported in the literature. These include Levec mode, Kan-Liquid mode, and super prewetting.…”

Section: Introductionmentioning

confidence: 99%

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Estimation of Wetting Efficiency in Trickle-Bed Reactors for Nonlinear Kinetics

Mogalicherla

Sharma

Kunzru

2009

Ind. Eng. Chem. Res.

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A procedure has been developed for estimating the wetting efficiency in a trickle-bed reactor by using the conversion data obtained for a reaction following nonlinear kinetics. For this purpose, the hydrogenation of α-methylstyrene on 0.5 wt % Pd/Al2O3 catalyst was studied in a batch slurry reactor (1.0−6.0 atm, 313−343 K), as well as in a trickle-bed reactor (313 K, 1.0−2.5 atm). The superficial velocities of gas and liquid in the trickle-bed reactor (TBR) were in the range of 0.25−1.0 cm/s and 0.06−0.24 cm/s, respectively. The intrinsic power-law kinetics, determined from the data obtained in the batch reactor, was used to calculate the effectiveness factors in the TBR. A comparison of these effectiveness factors with those calculated assuming complete external wetting showed that the wetting was not complete. The external wetting efficiencies (f) were determined using the method proposed by Ramachandran and Smith [AIChE J.197925538.]. To this end, effectiveness factors for the catalyst completely covered with gas or liquid were estimated for this nonlinear kinetics by a previously published procedure. f varied between 40% and 75% with the liquid superficial velocity. The difference between f values calculated from the conversion data and from the correlation developed using residence time distribution (RTD) data was attributed to the presence of stagnant liquid zones between the catalyst particles.

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Section: Resultssupporting

confidence: 57%

Section: Introductionmentioning

confidence: 99%

Estimation of Wetting Efficiency in Trickle-Bed Reactors for Nonlinear Kinetics

Mogalicherla

Sharma

Kunzru

2009

Ind. Eng. Chem. Res.

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“…If the surface or the pores of the catalyst are not fully wetted and the vapor pressure of the liquid is significant, then the reaction can take place on the gas-solid interface exhibiting higher rates [3,5,6,10]. This is due to the enhancement of diffusion in the gas phase by a factor of 1000 and the worse heat abduction by a factor of 10 (in accordance with the ratios of diffusion and heat transfer coefficients between the gas and the liquid phase).…”

Section: Introductionmentioning

confidence: 78%

Gas‐Liquid Mass Transfer in a Bench‐Scale Trickle Bed Reactor used for Benzene Hydrogenation

Metaxas¹,

Papayannakos²

2008

Chem Eng & Technol

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The gas-liquid mass transfer coefficients (MTCs) of a trickle bed reactor used for the study of benzene hydrogenation were investigated. The Ni/Al 2 O 3 catalyst bed was diluted with a coarse-grained inert carborundum (SiC) particle catalyst. Gasliquid mass transfer coefficients were estimated by using a heterogeneous model for reactor simulation, incorporating reaction kinetics, vapor-liquid equilibrium, and catalyst particle internal mass transfer apart from gas-liquid interface mass transfer. The effects of liquid axial dispersion and the catalyst wetting efficiency are shown to be negligible. Partial external mass transfer coefficients are correlated with gas superficial velocity, and comparison between them and those obtained from experiments conducted on a bed diluted with fine particles is also presented. On both sides of the gas-liquid interface the hydrogen mass transfer coefficient is higher than the corresponding benzene one and both increase significantly with gas velocity. The gas-side mass transfer limitations appear to be higher in the case of dilution with fine particles. On the liquid side, the mass transfer resistances are higher in the case of dilution with coarse inerts for gas velocities up to 3 · 10 -2 cm/sec, while for higher gas velocities this was inversed and higher mass transfer limitations were obtained for the beds diluted with fine inerts.

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“…Ž . and Hanika 1994, and Castellari et al 1997 . Another is the catalyst-scale study on the physiochemical aspects, as re-Ž .…”

Section: Introductionmentioning

confidence: 99%