Special Issue "Catalytic Methods in Flow Chemistry"

A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Environmental Catalysis".

Deadline for manuscript submissions: closed (31 January 2019).

Special Issue Editors

Guest Editor
Prof. Dr. Christophe Len Website E-Mail
PSL Research University, IRCP, UMR 8247 CNRS Chimie ParisTech, 11 rue Pierre et Marie Curie, F-75005 Paris, France
Interests: green chemistry; organic chemistry; catalysis
Guest Editor
Prof. Dr. Renzo Luisi Website E-Mail
Department of Pharmacy – Drug Sciences, University of Bari “A. Moro” via E. Orabona 4, 70125 – Bari - Italy
Interests: flow chemistry; microreactor technology; organometallic chemistry (lithium, magnesium); carbenoids; boron-, fluorine-, sulfur-chemistry; NMR spectroscopy; molecular dynamics; asymmetric synthesis; heterocyclic chemistry

Special Issue Information

Dear Colleagues,

The chemical industry generates a large variety of products, including (i) basic chemicals, e.g., polymers, petrochemicals, and basic inorganics; (ii) specialty chemicals for crop protection, paints, inks, colorants, textiles, paper and engineering; and (iii) consumer chemicals, including detergents, soaps, etc. Aiming to improve the intensification of the process, chemists have recently established chemical reactions based on catalysis, as well as alternative technologies, such as continuous flow.

The aim of this Special Issue is to cover promising recent research and novel trends in the field of novel catalytic reactions (homogeneous, heterogeneous, and enzymatic, as well as their combinations) in continuous flow chemistry. Recent conversion of starting material issued from petroleum resources or biomass into high-added value chemicals will be reported. 

Prof. Dr. Christophe Len
Prof. Dr. Renzo Luisi
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Catalysts is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Catalysis
  • Continuous flow reaction
  • Chemical catalysis
  • Enzymatic catalysis
  • Chemical engineering
  • Biomass valorization
  • Petroleum resources
  • Alternative technology
  • Microwave chemistry
  • Ultrasound chemistry
  • Photochemistry

Published Papers (11 papers)

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Editorial

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Open AccessEditorial
Catalytic Methods in Flow Chemistry
Catalysts 2019, 9(8), 663; https://doi.org/10.3390/catal9080663 - 02 Aug 2019
Abstract
Continuous flow chemistry is radically changing the way of performing chemical synthesis, and several chemical and pharmaceutical companies are now investing in this enabling technology [...] Full article
(This article belongs to the Special Issue Catalytic Methods in Flow Chemistry)

Research

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Open AccessArticle
Microwave-Assisted Homogeneous Acid Catalysis and Chemoenzymatic Synthesis of Dialkyl Succinate in a Flow Reactor
Catalysts 2019, 9(3), 272; https://doi.org/10.3390/catal9030272 - 16 Mar 2019
Cited by 1
Abstract
Two new continuous flow systems for the production of dialkyl succinates were developed via the esterification of succinic acid, and via the trans-esterification of dimethyl succinate. The first microwave-assisted continuous esterification of succinic acid with H2SO4 as a chemical homogeneous [...] Read more.
Two new continuous flow systems for the production of dialkyl succinates were developed via the esterification of succinic acid, and via the trans-esterification of dimethyl succinate. The first microwave-assisted continuous esterification of succinic acid with H2SO4 as a chemical homogeneous catalyst was successfully achieved via a single pass (ca 320 s) at 65–115 °C using a MiniFlow 200ss Sairem Technology. The first continuous trans-esterification of dimethyl succinate with lipase Cal B as an enzymatic catalyst was developed using a Syrris Asia Technology, with an optimal reaction condition of 14 min at 40 °C. Dialkyl succinates were produced with the two technologies, but higher productivity was observed for the microwave-assisted continuous esterification using chemical catalysts. The continuous flow trans-esterification demonstrated a number of advantages, but it resulted in lower yield of the target esters. Full article
(This article belongs to the Special Issue Catalytic Methods in Flow Chemistry)
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Open AccessArticle
Continuous-Flow Hydrogenation of Methyl Levulinate Promoted by Zr-Based Mesoporous Materials
Catalysts 2019, 9(2), 142; https://doi.org/10.3390/catal9020142 - 02 Feb 2019
Cited by 5
Abstract
Several Zr-based materials, including ZrO2 and Zr-SBA-15, with different silicon/zirconium molar ratios, and ZrO2/Si-SBA-15 (where SBA-15 stands for Santa Barbara Amorphous material no. 15), have been prepared as hydrogenation catalysts. The materials were characterized using different characterization techniques including X-ray [...] Read more.
Several Zr-based materials, including ZrO2 and Zr-SBA-15, with different silicon/zirconium molar ratios, and ZrO2/Si-SBA-15 (where SBA-15 stands for Santa Barbara Amorphous material no. 15), have been prepared as hydrogenation catalysts. The materials were characterized using different characterization techniques including X-ray diffraction (XRD), N2 porosimetry, scanning electron microscopy (SEM/EDX), diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) of pyridine adsorption and the pulsed chromatographic method using pyridine and 2,6-dimethylpyridine as probe molecules, mainly, have been employed for the characterization of the structural, textural, and acidic properties of the synthesized materials, respectively. The catalysts have been evaluated in the hydrogenation reaction of methyl levulinate using 2-propanol as hydrogen donor solvent. The reaction conditions were investigated and stablished at 30 bar system pressure with a reaction temperature of 200 °C using around 0.1 g of catalyst and a flow rate of 0.2 mL/min flow rate of a 0.3 M methyl levulinate solution in 2-propanol. All catalysts employed in this work exhibited good catalytic activities under the investigated conditions, with conversion values in the 15–89% range and, especially, selectivity to Υ-valerolactone in the range of 76–100% (after one hour time on stream). The highest methyl levulinate conversion and selectivity was achieved by ZrO2/Si-SBA-15 which can be explained by the higher dispersion of ZrO2 particles together with a highest accessibility of the Zr sites as compared with other materials such as Zr-SBA-15, also investigated in this work. Full article
(This article belongs to the Special Issue Catalytic Methods in Flow Chemistry)
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Open AccessArticle
Improving Productivity of Multiphase Flow Aerobic Oxidation Using a Tube-in-Tube Membrane Contactor
Catalysts 2019, 9(1), 95; https://doi.org/10.3390/catal9010095 - 17 Jan 2019
Cited by 1
Abstract
The application of flow reactors in multiphase catalytic reactions represents a promising approach for enhancing the efficiency of this important class of chemical reactions. We developed a simple approach to improve the reactor productivity of multiphase catalytic reactions performed using a flow chemistry [...] Read more.
The application of flow reactors in multiphase catalytic reactions represents a promising approach for enhancing the efficiency of this important class of chemical reactions. We developed a simple approach to improve the reactor productivity of multiphase catalytic reactions performed using a flow chemistry unit with a packed bed reactor. Specifically, a tube-in-tube membrane contactor (sparger) integrated in-line with the flow reactor has been successfully applied to the aerobic oxidation of benzyl alcohol to benzaldehyde utilizing a heterogeneous palladium catalyst in the packed bed. We examined the effect of sparger hydrodynamics on reactor productivity quantified by space time yield (STY). Implementation of the sparger, versus segmented flow achieved with the built in gas dosing module (1) increased reactor productivity 4-fold quantified by space time yield while maintaining high selectivity and (2) improved process safety as demonstrated by lower effective operating pressures. Full article
(This article belongs to the Special Issue Catalytic Methods in Flow Chemistry)
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Open AccessArticle
Catalytic Hydrodechlorination of Chlorophenols in a Continuous Flow Pd/CNT-Ni Foam Micro Reactor Using Formic Acid as a Hydrogen Source
Catalysts 2019, 9(1), 77; https://doi.org/10.3390/catal9010077 - 12 Jan 2019
Cited by 1
Abstract
Catalytic hydrodechlorination (HDC) has been considered as a promising method for the treatment of wastewater containing chlorinated organic pollutants. A continuous flow Pd/carbon nanotube (CNT)-Ni foam micro reactor system was first developed for the rapid and highly efficient HDC with formic acid (FA) [...] Read more.
Catalytic hydrodechlorination (HDC) has been considered as a promising method for the treatment of wastewater containing chlorinated organic pollutants. A continuous flow Pd/carbon nanotube (CNT)-Ni foam micro reactor system was first developed for the rapid and highly efficient HDC with formic acid (FA) as a hydrogen source. This micro reactor system, exhibiting a higher catalytic activity of HDC than the conventional packed bed reactor, reduced the residence time and formic acid consumption significantly. The desired outcomes (dichlorination >99.9%, 4-chlorophenol outlet concentration <0.1 mg/L) can be obtained under a very low FA/substrate molar ratio (5:1) and short reaction cycle (3 min). Field emission scanning electron microcopy (FESEM) and deactivation experiment results indicated that the accumulation of phenol (the main product during the HDC of chlorophenols) on the Pd catalyst surface can be the main factor for the long-term deactivation of the Pd/CNT-Ni foam micro reactor. The catalytic activity deactivation of the micro reactor could be almost completely regenerated by the efficient removal of the absorbed phenol from the Pd catalyst surface. Full article
(This article belongs to the Special Issue Catalytic Methods in Flow Chemistry)
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Open AccessFeature PaperArticle
Mg-Catalyzed OPPenauer Oxidation—Application to the Flow Synthesis of a Natural Pheromone
Catalysts 2018, 8(11), 529; https://doi.org/10.3390/catal8110529 - 08 Nov 2018
Cited by 1
Abstract
The so-called OPPenauer oxidation is well known for its ability to oxidize valuable alcohols into their corresponding aldehydes or ketones. In particular, it has proven to be extremely successful in the oxidation of sterols. On the other hand, its application—in the original formulation—to [...] Read more.
The so-called OPPenauer oxidation is well known for its ability to oxidize valuable alcohols into their corresponding aldehydes or ketones. In particular, it has proven to be extremely successful in the oxidation of sterols. On the other hand, its application—in the original formulation—to the obtainment of ketones outside the field of steroids met a more limited success because of less favorable thermodynamics and side reactions. To circumvent these issues, the first example of magnesium-catalyzed OPPenauer oxidation is described. The oxidation of primary and secondary alcohol was performed using pivaldehyde or bromaldehyde as the oxidant and cheap magnesium tert-butoxide as catalyst. Decent to excellent yields were obtained using reasonable catalytic charge. The synthesis of a pheromone stemming from the Rhynchophorus ferrugineus was obtained by tandem addition-oxidation of 2-methylpentanal and the process was successfully applied to continuous flow on a multigram scale. Full article
(This article belongs to the Special Issue Catalytic Methods in Flow Chemistry)
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Open AccessArticle
Prediction of In-Situ Gasification Chemical Looping Combustion Effects of Operating Conditions
Catalysts 2018, 8(11), 526; https://doi.org/10.3390/catal8110526 - 07 Nov 2018
Cited by 1
Abstract
Chemical Looping Combustion (CLC) has been considered as one of the most promising technologies to implement CO2 capture with low energy penalty. A comprehensive three-dimensional numerical model integrating gas–solid flow and reactions, based on the authors’ previous work (Energy Fuels 2013, 27, [...] Read more.
Chemical Looping Combustion (CLC) has been considered as one of the most promising technologies to implement CO2 capture with low energy penalty. A comprehensive three-dimensional numerical model integrating gas–solid flow and reactions, based on the authors’ previous work (Energy Fuels 2013, 27, 2173–2184), is applied to simulate the in-situ Gasification Chemical Looping Combustion (iG-CLC) process in a circulating fluidized bed (CFB) riser fuel reactor. Extending from the previous work, the present study further validates the model and investigates the effects of several important operating conditions, i.e., solids flux, steam flow and operating pressure, on the gas–solid flow behaviors, CO2 concentration and fuel conversion, comprehensively. The simulated fuel reactor has a height of 5 m and an internal diameter of 60 mm. The simulated oxygen carrier is a Norwegian ilmenite and the simulated fuel is a Colombian bituminous coal. The results of this simulation work have shown that an increase in the solids flux can promote CO2 concentration, but may also have a negative effect on carbon conversion. A decrease in the steam flow leads to positive effects on not only the CO2 concentration but also the carbon conversion. However, the reduction of steam flow is limited by the CFB operation process. An increase in the operating pressure can improve both the CO2 concentration and carbon conversion and therefore, the CFB riser fuel reactor of a practical iG-CLC system is recommended to be designed and operated under a certain pressurized conditions. Full article
(This article belongs to the Special Issue Catalytic Methods in Flow Chemistry)
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Open AccessArticle
A Novel Method for the Prediction of Erosion Evolution Process Based on Dynamic Mesh and Its Applications
Catalysts 2018, 8(10), 432; https://doi.org/10.3390/catal8100432 - 30 Sep 2018
Cited by 1
Abstract
Particle erosion is a commonly occurring phenomenon, and it plays a significantly important role in service life. However, few simulations have replicated erosion, especially the detailed evolution process. To address this complex issue, a new method for establishing the solution of the erosion [...] Read more.
Particle erosion is a commonly occurring phenomenon, and it plays a significantly important role in service life. However, few simulations have replicated erosion, especially the detailed evolution process. To address this complex issue, a new method for establishing the solution of the erosion evolution process was developed. The approach is introduced with the erosion model and the dynamic mesh. The erosion model was applied to estimate the material removal of erosion, and the dynamic mesh technology was used to demonstrate the surface profile of erosion. Then, this method was applied to solve a typical case—the erosion surface deformation and the expiry period of an economizer bank in coal-fired power plants. The mathematical models were set up, including gas motion, particle motion, particle-wall collision, and erosion. Such models were solved by computational fluid dynamics (CFD) software (ANSYS FLUENT), which describes the evolution process of erosion based on the dynamic mesh. The results indicate that: (1) the prediction of the erosion profile calculated by the dynamic mesh is in good agreement with that on-site; (2) the global/local erosion loss and the maximum erosion depth is linearly related to the working time at the earlier stage, but the growth of the maximum erosion depth slows down gradually in the later stage; (3) the reason for slowing down is that the collision point trajectory moves along the increasing direction of the absolute value of θ as time increases; and (4) the expiry period is shortened as the ash diameter increases. Full article
(This article belongs to the Special Issue Catalytic Methods in Flow Chemistry)
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Open AccessArticle
From a Sequential Chemo-Enzymatic Approach to a Continuous Process for HMF Production from Glucose
Catalysts 2018, 8(8), 335; https://doi.org/10.3390/catal8080335 - 17 Aug 2018
Cited by 3
Abstract
Notably available from the cellulose contained in lignocellulosic biomass, glucose is a highly attractive substrate for eco-efficient processes towards high-value chemicals. A recent strategy for biomass valorization consists on combining biocatalysis and chemocatalysis to realise the so-called chemo-enzymatic or hybrid catalysis. Optimisation of [...] Read more.
Notably available from the cellulose contained in lignocellulosic biomass, glucose is a highly attractive substrate for eco-efficient processes towards high-value chemicals. A recent strategy for biomass valorization consists on combining biocatalysis and chemocatalysis to realise the so-called chemo-enzymatic or hybrid catalysis. Optimisation of the glucose conversion to 5-hydroxymethylfurfural (HMF) is the object of many research efforts. HMF can be produced by chemo-catalyzed fructose dehydration, while fructose can be selectively obtained from enzymatic glucose isomerization. Despite recent advances in HMF production, a fully integrated efficient process remains to be demonstrated. Our innovative approach consists on a continuous process involving enzymatic glucose isomerization, selective arylboronic-acid mediated fructose complexation/transportation, and chemical fructose dehydration to HMF. We designed a novel reactor based on two aqueous phases dynamically connected via an organic liquid membrane, which enabled substantial enhancement of glucose conversion (70%) while avoiding intermediate separation steps. Furthermore, in the as-combined steps, the use of an immobilized glucose isomerase and an acidic resin facilitates catalyst recycling. Full article
(This article belongs to the Special Issue Catalytic Methods in Flow Chemistry)
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Open AccessArticle
Selective Reduction of Ketones and Aldehydes in Continuous-Flow Microreactor—Kinetic Studies
Catalysts 2018, 8(5), 221; https://doi.org/10.3390/catal8050221 - 22 May 2018
Cited by 3
Abstract
In this work, the kinetics of Meerwein–Ponndorf–Verley chemoselective reduction of carbonyl compounds was studied in monolithic continuous-flow microreactors. To the best of our knowledge, this is the first report on the MPV reaction kinetics performed in a flow process. The microreactors are a [...] Read more.
In this work, the kinetics of Meerwein–Ponndorf–Verley chemoselective reduction of carbonyl compounds was studied in monolithic continuous-flow microreactors. To the best of our knowledge, this is the first report on the MPV reaction kinetics performed in a flow process. The microreactors are a very attractive alternative to the batch reactors conventionally used in this process. The proposed micro-flow system for synthesis of unsaturated secondary alcohols proved to be very efficient and easily controlled. The microreactors had reactive cores made of zirconium-functionalized silica monoliths of excellent catalytic properties and flow characteristics. The catalytic experiments were carried out with the use of 2-butanol as a hydrogen donor. Herein, we present the kinetic parameters of cyclohexanone reduction in a flow reactor and data on the reaction rate for several important ketones and aldehydes. The lack of diffusion constraints in the microreactors was demonstrated. Our results were compared with those from other authors and demonstrate the great potential of microreactor applications in fine chemical and complex intermediate manufacturing. Full article
(This article belongs to the Special Issue Catalytic Methods in Flow Chemistry)
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Review

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Open AccessFeature PaperReview
Titanium Dioxide as a Catalyst in Biodiesel Production
Catalysts 2019, 9(1), 75; https://doi.org/10.3390/catal9010075 - 11 Jan 2019
Cited by 2
Abstract
The discovery of alternative fuels that can replace conventional fuels has become the goal of many scientific researches. Biodiesel is produced from vegetable oils through a transesterification reaction that converts triglycerides into fatty acid methyl esters (FAME), with the use of a low [...] Read more.
The discovery of alternative fuels that can replace conventional fuels has become the goal of many scientific researches. Biodiesel is produced from vegetable oils through a transesterification reaction that converts triglycerides into fatty acid methyl esters (FAME), with the use of a low molecular weight alcohol, in different reaction conditions and with different types of catalysts. Titanium dioxide has shown a high potential as heterogeneous catalyst due to high surface area, strong metal support interaction, chemical stability, and acid–base property. This review focused on TiO2 as heterogeneous catalyst and its potential applications in the continuous flow production of biodiesel. Furthermore, the use of micro reactors, able to make possible chemical transformations not feasible with traditional techniques, will enable a reduction of production costs and a greater environmental protection. Full article
(This article belongs to the Special Issue Catalytic Methods in Flow Chemistry)
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