scholarly journals Continuous Flow Friedel–Crafts Alkylation Catalyzed by Silica Supported Phosphotungstic Acid: An Environmentally Benign Process

2021 ◽  
Author(s):  
Zsófia Császár ◽  
Tatjána Juzsakova ◽  
Miklós Jakab ◽  
Szabolcs Balogh ◽  
Ágnes Szegedi ◽  
...  
Keyword(s):  
Flow Rate ◽  
Continuous Flow ◽  
Phosphotungstic Acid ◽  
Flow Reactor ◽  
Analytical Techniques ◽  
Catalyst System ◽  
Molar Ratio ◽  
Flow Mode ◽  
Reaction Conditions ◽  
Composite Catalysts

AbstractSix silica-supported phosphotungstic acid catalysts (PTA/SiO2) of different composition (20–70 wt% PTA content) have been synthesized and characterized by elemental analysis, BET, BJH, NH3-TPD methods, FT-IR spectroscopy of adsorbed pyridine and 1H MAS NMR techniques. The new composite catalysts were first applied in the Friedel–Crafts alkylation of toluene with 1-octene as a benchmark process under batch conditions in order to screen their activity and recyclability. The combined analytical techniques together with the catalytic studies enabled the identification of the main factors affecting the activity of the catalysts. Based on these preliminary experiments, the best performing catalyst system (50 wt% PTA/SiO2) was investigated in continuous flow mode using an in-house-made flow reactor. The thorough screening of the reaction conditions (temperature, toluene/1-octene molar ratio and flow rate) provided firm evidence that the 50 wt% PTA/SiO2 composite is highly active, selective and stable catalyst under mild reaction conditions even at elevated flow rate. Additionally, the catalyst used in the flow mode could successfully be regenerated and reused in the alkylation process.

scholarly journals Flow-mode biodiesel production from palm oil using a pressurized microwave reactor

2019 ◽  
Vol 8 (1) ◽  
pp. 8-14 ◽  
Author(s):  
Seyed Mohammad Safieddin Ardebili ◽  
Xinyu Ge ◽  
Giancarlo Cravotto
Keyword(s):  
Palm Oil ◽  
Irradiation Time ◽  
Biodiesel Production ◽  
Molar Ratio ◽  
Flow Mode ◽  
Reaction Conditions ◽  
Surface Method ◽  
Optimized Conditions ◽  
Reactor Pressure ◽  
Palm Oil Biodiesel

Abstract The factors that influence microwave-assisted biodiesel production reactions have been analyzed in this investigation. The studied parameters included microwave (MW) power, irradiation time, and reactor pressure. The response surface method was used to optimize the reaction conditions. The conversion for the 6:1 methanol/oil molar ratio and 1% catalyst ranged from 68.4% to 96.71%. The optimized conditions were found to be 138 s of MW irradiation at 780 W and 7 bar pressure. The conversion at this point was 97.82%. Biodiesel yield increased at higher radiation times (90–130 s) and pressures (5–7 bar). Results show that MW power and irradiation time have significant effects at the 1% level, whereas pressure had significant effects at the 5% level on biodiesel production in this range. The major properties of the palm oil biodiesel produced herein have met the requirements of the EN 14214 methyl ester standard.

scholarly journals Continuous flow photolysis of aryl azides: Preparation of 3H-azepinones

2011 ◽  
Vol 7 ◽  
pp. 1124-1129 ◽  
Author(s):  
Farhan R Bou-Hamdan ◽  
François Lévesque ◽  
Alexander G O'Brien ◽  
Peter H Seeberger
Keyword(s):  
Continuous Flow ◽  
Flow Reactor ◽  
Photochemical Reactions ◽  
Fine Tuning ◽  
Aryl Azides ◽  
Reaction Conditions ◽  
Ethylene Polymer

Photolysis of aryl azides to give nitrenes, and their subsequent rearrangement in the presence of water to give 3H-azepinones, is performed in continuous flow in a photoreactor constructed of fluorinated ethylene polymer (FEP) tubing. Fine tuning of the reaction conditions using the flow reactor allowed minimization of secondary photochemical reactions.

Nanocrystals Synthesis by Microreactors

2006 ◽  
Vol 45 ◽  
pp. 652-659
Author(s):  
Hiroyuki Nakamura ◽  
Masato Uehara ◽  
Hideaki Maeda
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Continuous Flow ◽  
Flow Reactor ◽  
Reaction Conditions ◽  
Control Reaction ◽  
Continuous Flow Reactor

A microreactor is a continuous flow reactor, which can control reaction conditions precisely. We applied the microreactors to CdSe based nanocrystals synthesis and tuning particle size, optical properties. Furthermore, homogeneous coating of ZnS and its coating amount tuning was possible for optical properties improvement.

scholarly journals The development and evaluation of a continuous flow process for the lipase-mediated oxidation of alkenes

2009 ◽  
Vol 5 ◽  
Author(s):  
Charlotte Wiles ◽  
Marcus J Hammond ◽  
Paul Watts
Keyword(s):  
Continuous Flow ◽  
Flow Reactor ◽  
Preliminary Investigation ◽  
Enzymatic Oxidation ◽  
High Yield ◽  
Reaction Conditions ◽  
Flow Process ◽  
Continuous Flow Reactor ◽  
Yield And Purity ◽  
Mediated Oxidation

We report the use of an immobilised form of Candida antarctica lipase B, Novozym® 435, in a preliminary investigation into the development of a continuous flow reactor capable of performing the chemo-enzymatic oxidation of alkenes in high yield and purity, utilising the commercially available oxidant hydrogen peroxide (100 volumes). Initial investigations focussed on the lipase-mediated oxidation of 1-methylcyclohexene, with the optimised reaction conditions subsequently employed for the epoxidation of an array of aromatic and aliphatic alkenes in 97.6 to 99.5% yield and quantitative purity.

scholarly journals Continuous-Flow Process for Glycerol Conversion to Solketal Using a Brönsted Acid Functionalized Carbon-Based Catalyst

Catalysts ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 609 ◽  
Author(s):  
Vanesa Domínguez-Barroso ◽  
Concepción Herrera ◽  
María Ángeles Larrubia ◽  
Rafael González-Gil ◽  
Marina Cortés-Reyes ◽  
...  
Keyword(s):  
Continuous Flow ◽  
Flow Reactor ◽  
Batch Reactor ◽  
High Surface ◽  
Molar Ratio ◽  
Fuel Additive ◽  
Flow Process ◽  
Glycerol Conversion ◽  
Structured Catalyst ◽  
Carbon Based

The acetalization of glycerol with acetone represents a strategy for its valorization into solketal as a fuel additive component. Thus, acid carbon-based structured catalyst (SO3H-C) has been prepared, characterized and tested in this reaction. The structured catalyst (L = 5 cm, d = 1 cm) showed a high surface density of acidic sites (2.9 mmol H+ g−1) and a high surface area. This catalyst is highly active and stable in the solketal reaction production in a batch reactor system and in a continuous downflow reactor, where several parameters were studied such as the variation of time of reaction, temperature, acetone/glycerol molar ratio (A/G) and weight hourly space velocity (WHSV). A complete glycerol conversion and 100% of solketal selectivity were achieved working in the continuous flow reactor equipped with distillation equipment when WHSV is 2.9 h−1, A/G = 8 at 57 °C in a co-solvent free operation. The catalyst maintained its activity under continuous flow even after 300 min of reaction.

Intensification of Free-Radical Racemization for a Non-activated Amine in a Continuous Flow Reactor

Synthesis ◽  
2020 ◽  
Vol 52 (22) ◽  
pp. 3389-3396
Author(s):  
Frédéric C. Toussaint ◽  
Thierry Defrance ◽  
Serge Decouvreur ◽  
Nicolas Carly ◽  
Alain Merschaert
Keyword(s):  
Free Radical ◽  
Pharmaceutical Industry ◽  
Chiral Separation ◽  
Process Design ◽  
Continuous Flow ◽  
Flow Reactor ◽  
Flow Mode ◽  
Environmental Footprint ◽  
Radical Initiator ◽  
Continuous Flow Reactor

The free-radical racemization of non-activated amines is a powerful tool for process design in the pharmaceutical industry, allowing the recycling of undesired enantiomers after chiral separation. This paper describes the development of the free-radical racemization of a key API intermediate in a continuous flow reactor. Upon development, a significant reduction of the solvent usage and radical initiator was made possible thanks to the conversion into a continuous flow mode. This intensification positively impacted both the environmental footprint and the safety of the reaction as well as maintaining satisfactory productivity.

scholarly journals Enantioselective Transamination in Continuous Flow Mode with Transaminase Immobilized in a Macrocellular Silica Monolith

2017 ◽  
Author(s):  
Ludivine van den Biggelaar ◽  
Patrice Soumillion ◽  
Damien P. Debecker
Keyword(s):  
Continuous Flow ◽  
Preferential Flow ◽  
Kinetic Resolution ◽  
Flow Reactor ◽  
Sol Gel ◽  
Flow Mode ◽  
Chiral Amine ◽  
Silica Monoliths ◽  
Covalent Grafting ◽  
Heterogeneous Biocatalysts

ω-Transaminases have been immobilized on macrocellular silica monoliths and used as heterogeneous biocatalysts in a continuous flow mode enantioselective transamination reaction. The support was prepared by a sol-gel method based on emulsion-templating. The enzyme was immobilized on the structured silica monoliths both by adsorption, and by covalent grafting using amino-functionalized silica monoliths and glutaraldehyde as a coupling agent. A simple reactor set-up based on the use of a heat-shrinkable Teflon tube is presented and successfully used for the continuous flow kinetic resolution of a chiral amine, 4-bromo-α-methylbenzylamine. The porous structure of the supports ensures effective mass transfer and the reactor works in the plug flow regime without preferential flow paths. When immobilized in the monolith and used in the flow reactor, transaminases retain their activity and their enantioselectivity. The solid biocatalyst is also shown to be stable both on stream and during storage. These essential features pave the way to the successful development of an environmentally friendly process for chiral amines production.

scholarly journals Mass Transfer in Hierarchical Silica Monoliths Loaded With Pt in the Continuous-Flow Liquid-Phase Hydrogenation of p-Nitrophenol

2021 ◽  
Vol 3 ◽  
Author(s):  
Haseeb Ullah Khan Jatoi ◽  
Michael Goepel ◽  
David Poppitz ◽  
Richard Kohns ◽  
Dirk Enke ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Flow Rate ◽  
Continuous Flow ◽  
Flow Reactor ◽  
Sol Gel ◽  
Catalyst Support ◽  
Test Reaction ◽  
Silica Monoliths ◽  
Monolithic Catalysts ◽  
Liquid Phase Hydrogenation

Sol-gel-based silica monoliths with hierarchical mesopores/macropores are promising catalyst support and flow reactors. Here, we report the successful preparation of cylindrically shaped Pt-loaded silica monoliths (length: 2 cm, diameter: 0.5 cm) with a variable mean macropore width of 1, 6, 10, or 27 μm at a fixed mean mesopore width of 17 nm. The Pt-loaded monolithic catalysts were housed in a robust cladding made of borosilicate glass for use as a flow reactor. The monolithic reactors exhibit a permeability as high as 2 μm2 with a pressure drop below 9 bars over a flow rate range of 2–20 cm3 min−1 (solvent: water). The aqueous-phase hydrogenation of p-nitrophenol to p-aminophenol with NaBH4 as a reducing agent was used as a test reaction to study the influence of mass transfer on catalytic activity in continuous flow. No influence of flow rate on conversion at a fixed contact time of 2.6 s was observed for monolithic catalysts with mean macropore widths of 1, 10, or 27 µm. As opposed to earlier studies conducted at much lower flow velocities, this strongly indicates the absence of external mass-transfer limitations or stagnant layer formation in the macropores of the monolithic catalysts.

scholarly journals Enantioselective Transamination in Continuous Flow Mode with Transaminase Immobilized in a Macrocellular Silica Monolith

2017 ◽  
Author(s):  
Ludivine van den Biggelaar ◽  
Patrice Soumillion ◽  
Damien P. Debecker
Keyword(s):  
Continuous Flow ◽  
Preferential Flow ◽  
Kinetic Resolution ◽  
Flow Reactor ◽  
Sol Gel ◽  
Flow Mode ◽  
Chiral Amine ◽  
Silica Monoliths ◽  
Covalent Grafting ◽  
Heterogeneous Biocatalysts

ω-Transaminases have been immobilized on macrocellular silica monoliths and used as heterogeneous biocatalysts in a continuous flow mode enantioselective transamination reaction. The support was prepared by a sol-gel method based on emulsion templating. The enzyme was immobilized on the structured silica monoliths both by adsorption, and by covalent grafting using amino-functionalized silica monoliths and glutaraldehyde as a coupling agent. A simple reactor set-up based on the use of a heat-shrinkable Teflon tube is presented and successfully used for the continuous flow kinetic resolution of a chiral amine, 4-bromo-α-methylbenzylamine. The porous structure of the supports ensures effective mass transfer and the reactor works in the plug flow regime without preferential flow paths. When immobilized in the monolith and used in the flow reactor, transaminases retain their activity and their enantioselectivity. The solid biocatalyst is also shown to be stable both on stream and during storage. These essential features pave the way to the successful development of an environmentally friendly process for chiral amines production.

Synthesis of unsaturated secondary amines by direct reductive amination of aliphatic aldehydes with nitroarenes over Au/Al2O3catalyst in continuous flow mode

RSC Advances ◽  
2016 ◽  
Vol 6 (91) ◽  
pp. 88366-88372 ◽  
Author(s):  
A. L. Nuzhdin ◽  
E. A. Artiukha ◽  
G. A. Bukhtiyarova ◽  
S. Yu Zaytsev ◽  
P. E. Plyusnin ◽  
...  
Keyword(s):  
Continuous Flow ◽  
Reductive Amination ◽  
Flow Reactor ◽  
Secondary Amines ◽  
Flow Mode ◽  
Aliphatic Aldehydes

Unsaturated secondary amines were successfully synthesized by reductive amination of aldehydes with nitroarenes over Au/Al2O3catalyst in a flow reactor.

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