Trickle bed reactors: Effect of liquid flow modulation on catalytic activity

Ayude, María Alejandra; Cechini, J. O.; Cassanello, Miryan; Martı́nez, Osvaldo; Haure, Patricia M.

doi:10.1016/j.ces.2008.07.024

Cited by 17 publications

(13 citation statements)

References 17 publications

(28 reference statements)

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“…This fact was already checked and reported in a previous work [12]. To start an experiment, the liquid was circulated through the bed for about 20 min in the absence of oxygen.…”

Section: Methodssupporting

confidence: 54%

“…This effect is observed when the limiting reactant is present in the gas phase. However, it should be mentioned that excessive exposure to oxygen may lead to catalyst deactivation by over-oxidation [12]. In these regions, mass transfer of the gaseous reactant is enhanced and the ethanol oxidation rate increases.…”

Section: Resultsmentioning

confidence: 99%

“…Reaction rates were evaluated considering the molar concentration in the liquid reservoir and the mass accumulated in the cold trap, as described in Ayude et al [12]. As conversion per pass was very low, the reaction was allowed to proceed for a certain time meanwhile samples were taken.…”

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Yield Optimization in a Cycled Trickle‐Bed Reactor: Ethanol Catalytic Oxidation as a Case Study

Ayude¹,

Cassanello²,

Martı́nez³

et al. 2012

Chem Eng & Technol

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The effect of slow ON-OFF liquid flow modulation on the yield of consecutive reactions is investigated for oxidation of aqueous ethanol solutions using a 0.5 % Pd/Al 2 O 3 commercial catalyst in a laboratory trickle-bed reactor. Experiments with modulated liquid flow rate (MLFR) were performed under the same hydrodynamic conditions (degree of wetting, liquid holdup) as experiments with constant liquid flow rate (CLFR). Thus, the impact of the duration of wet and dry cycles as well as the period can be independently investigated. Depending on cycling conditions, acetaldehyde or acetic acid production is favored with MLFR compared to CLFR. Results suggest both the opportunity and challenge of finding a way to tune the cycling parameters for producing the most appropriate product.

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“…This fact was already checked and reported in a previous work [12]. To start an experiment, the liquid was circulated through the bed for about 20 min in the absence of oxygen.…”

Section: Methodssupporting

confidence: 54%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Yield Optimization in a Cycled Trickle‐Bed Reactor: Ethanol Catalytic Oxidation as a Case Study

Ayude¹,

Cassanello²,

Martı́nez³

et al. 2012

Chem Eng & Technol

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“…These systems have been extensively used in hydrotreating and hydrodesulfurization in petroleum refining, petrochemical hydrogenation and oxidation processes, and methods of biochemical and detoxification of industrial waste water (Al-Dahhan et al, 1997;Dudukovic et al, 1999;Liu et al, 2008;Ayude et al, 2008;Rodrigo et al, 2009;Augier et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Mathematical modeling of a three-phase trickle bed reactor

Silva¹,

Abreu

2012

Braz. J. Chem. Eng.

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-The transient behavior in a three-phase trickle bed reactor system (N 2 /H 2 O-KCl/activated carbon, 298 K, 1.01 bar) was evaluated using a dynamic tracer method. The system operated with liquid and gas phases flowing downward with constant gas flow Q G = 2.50 x 10 -6 m 3 s -1 and the liquid phase flow (Q L ) varying in the range from 4.25x10 -6 m 3 s -1 to 0.50x10 -6 m 3 s -1 . The evolution of the KCl concentration in the aqueous liquid phase was measured at the outlet of the reactor in response to the concentration increase at reactor inlet. A mathematical model was formulated and the solutions of the equations fitted to the measured tracer concentrations. The order of magnitude of the axial dispersion, liquid-solid mass transfer and partial wetting efficiency coefficients were estimated based on a numerical optimization procedure where the initial values of these coefficients, obtained by empirical correlations, were modified by comparing experimental and calculated tracer concentrations. The final optimized values of the coefficients were calculated by the minimization of a quadratic objective function. Three correlations were proposed to estimate the parameters values under the conditions employed. By comparing experimental and predicted tracer concentration step evolutions under different operating conditions the model was validated.

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“…Alternative heterogeneous catalysts utilising oxygen or air as the oxidant offer vastly improved activity, selectivity and overall atom efficiency in alcohol selox (Scheme 3), but are particularly demanding due to the requirement to activate molecular oxygen and C-O bonds in close proximity at a surface in a solid-liquid-gas environment [39][40][41], and must also be scalable in terms of both catalyst synthesis and implementation. For example, continuous flow microreactors have been implemented in both homogeneous and heterogeneous aerobic selox, providing facile catalyst recovery from feedstreams for the latter [42,43], but their scale-up/out requires complex manifolding to ensure adequate oxygen dissolution uniform reactant mixing and delivery [44,45]. Efforts to overcome mass transport and solubility issues inherent to 3-phase catalysed oxidations have centred around the use of supercritical carbon dioxide to facilitate rapid diffusion of substrates to and products from the active catalyst site at modest temperatures [46] affording enhanced turnover frequencies (TOFs), selectivity and on-stream performance versus conventional batch operation in liquid organic solvents [47][48][49][50][51].…”

Section: Introductionmentioning

confidence: 99%

Catalysing Sustainable Fuel and Chemical Synthesis

Lee¹

2015

Advanced Biofuels

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Concerns over the economics of proven fossil fuel reserves, in concert with government and public acceptance of the anthropogenic origin of rising CO 2 emissions and associated climate change from such combustible carbon, are driving academic and commercial research into new sustainable routes to fuel and chemicals. The quest for such sustainable resources to meet the demands of a rapidly rising global population represents one of this century's grand challenges. Here, we discuss catalytic solutions to the clean synthesis of biodiesel, the most readily implemented and low cost, alternative source of transportation fuels, and oxygenated organic molecules for the manufacture of fine and speciality chemicals to meet future societal demands.

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Trickle bed reactors: Effect of liquid flow modulation on catalytic activity

Cited by 17 publications

References 17 publications

Yield Optimization in a Cycled Trickle‐Bed Reactor: Ethanol Catalytic Oxidation as a Case Study

Yield Optimization in a Cycled Trickle‐Bed Reactor: Ethanol Catalytic Oxidation as a Case Study

Mathematical modeling of a three-phase trickle bed reactor

Catalysing Sustainable Fuel and Chemical Synthesis

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