Process intensification in a photocatalytic membrane reactor: Analysis of the techniques to integrate reaction and separation

Roda, Giovanni Camera; Loddo, Vittorio; Palmisano, Leonardo; Parrino, Francesco; Santarelli, Francesco

doi:10.1016/j.cej.2016.06.019

Cited by 30 publications

(10 citation statements)

References 25 publications

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“…Furthermore, the permeated vanillin was recovered as highly pure crystals (≥99.8%) by freezing downstream in a liquid nitrogen trap, without further separation and purification steps. Due to the industrial relevance of vanillin, − the process was carefully optimized and kinetically modeled, and some engineering aspects were deeply approached.…”

Section: Selectivity Enhancement By Tuning Various Reaction Condition...supporting

confidence: 74%

Heterogeneous Photocatalysis for Selective Formation of High-Value-Added Molecules: Some Chemical and Engineering Aspects

et al. 2018

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This review deals with the parameters that influence heterogeneous photocatalysis (PC) for selective synthesis of high-value chemicals by itself or in combination with other technologies. In particular, the parameters related to the photocatalysts, such as crystallinity degree, type of polymorph, surface acid–base properties, exposure of particular crystalline facets, coupling of different semiconductors, position of the valence and conduction band edge, addition of doping agents, and those related to the reaction system, such as setup configuration and reactor geometry, type of solvent, type and amount of photocatalyst, affecting the selectivity toward specific products are described and discussed. The presented results highlight that a precise evaluation of the efficiency of the process is a challenging but necessary task to be approached in order to allow real applications of photocatalytic processes.

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Section: Selectivity Enhancement By Tuning Various Reaction Condition...supporting

confidence: 74%

Heterogeneous Photocatalysis for Selective Formation of High-Value-Added Molecules: Some Chemical and Engineering Aspects

et al. 2018

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“…The flow rate of the recirculated stream was sufficiently high to obtain very low values (much less than unity) of the Damköhler number, Da, and of the reciprocal of the Péclet number for membrane processes, 1/Pe [10]. In this way, the two separate apparatuses (reactor and membrane module) work in differential conditions and the coupling of the membrane separation and the reaction is almost complete [15]. Da and 1/Pe can be defined as: n van, in = 1 (mM) × 115 (L/h) = 115 mmol/h →1/Pe ≈ 0.87 × 10 −3 << 1.…”

Section: Methodsmentioning

confidence: 99%

A Dialysis Photocatalytic Reactor for the Green Production of Vanillin

et al. 2020

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In the present work, dialysis was used to recover vanillin while being produced by partial photocatalytic oxidation of ferulic acid in an aqueous solution at ambient temperature. The relatively high value of the permeate flux through a dense polyether-block amide membrane allowed continuously extracting vanillin from the reacting solution, thus avoiding its successive oxidation. The rate of vanillin formation was improved, compared to other reactor configurations, because intermediate compounds permeated from the reacting solution and did not hinder the reaction, while ferulic acid permeated in the opposite direction to partially replenish the reactor with the substrate. The photocatalytic membrane reactor obtained by the effective coupling of dialysis with the photocatalytic reaction improved the production yield. For instance, with the utilized experimental set up, the total amount of vanillin produced after 5 h in the membrane reactor was more than one-third higher than in the photocatalytic reactor without dialysis. The results obtained with a mathematical model agree with the experimentally observed behavior. The model allowed estimating vanillin diffusivity in the membrane and showed that concentration polarization might limit the process.

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“…Different continuous reactive systems have indicated that the conversion (X) increases with Da [7,13]. Simulated reactors with Dabetween 10 À5 and 10 2 showed the main aspects that control the conversion in membrane reactors [14,15,16,17] and other continuous reactors with interfacial mass transport [18,19].…”

Section: Introductionmentioning

confidence: 99%

Sizing of reactors by charts of Damköhler's number for solutions of dimensionless design equations

Otálvaro-Marín

Machuca-Martínez

2020

Heliyon

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The reaction kinetic rate and mass transport play an important role in the sizing and scale-up of reactors. The Damk€ ohler's dimensionless number (Da) is the quotient of these effects. A new interpretation of Da as a local property is introduced Daðx; y; z; tÞ. A new graphical methodology is proposed for the sizing and scale-up of unidirectional flow reactors and CSTRs. The partial differential equation (PDE) and algebraic that describe the continuity within these reactors transform into dimensionless variables, and the conversion at the output is expressed as a function of the conditions at the input Da 0 . The operating conditions as volumetric flow, residence time; design variables as reactor volume; and intrinsic reaction rate are involved in Da 0 . The equations are solved numerically to develop the design charts Da 0 vs X.The design volume is linear with Da 0 , and the conversion is obtained from the charts (Da 0 vs X) or vice versa. Using these charts avoids the analytical or numerical solution of the PDE that governs the unidirectional flow reactors becoming an easy tool for scale-up. The article portrays how to use these diagrams. Reactors with Da 0 < 0.1 have a low conversion per pass, the charts also allow estimating the number of recirculations required as a function of the overall conversion. Reactors with the same conversion have the same Da 0 , both laboratory and industrial scale. Then, the Danumber is presented as a fundamental parameter for design and scaling-up these reactors.

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Process intensification in a photocatalytic membrane reactor: Analysis of the techniques to integrate reaction and separation

Cited by 30 publications

References 25 publications

Heterogeneous Photocatalysis for Selective Formation of High-Value-Added Molecules: Some Chemical and Engineering Aspects

Heterogeneous Photocatalysis for Selective Formation of High-Value-Added Molecules: Some Chemical and Engineering Aspects

A Dialysis Photocatalytic Reactor for the Green Production of Vanillin

Sizing of reactors by charts of Damköhler's number for solutions of dimensionless design equations

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