scholarly journals Efficient and selective chemical transformations under flow conditions: The combination of supported catalysts and supercritical fluids

2011 ◽  
Vol 7 ◽  
pp. 1347-1359 ◽  
Author(s):  
M Isabel Burguete ◽  
Eduardo García-Verdugo ◽  
Santiago V Luis
Keyword(s):  
Supercritical Fluids ◽  
Supported Catalysts ◽  
Chemical Transformations ◽  
Flow Conditions ◽  
Catalytic Systems ◽  
Enhanced Diffusion ◽  
Long Term Stability ◽  
Current Trends ◽  
Liquid Phases ◽  
Combined Use

This paper reviews the current trends in the combined use of supported catalytic systems, either on solid supports or in liquid phases and supercritical fluids (scFs), to develop selective and enantioselective chemical transformations under continuous and semi-continuous flow conditions. The results presented have been selected to highlight how the combined use of those two elements can contribute to: (i) Significant improvements in productivity as a result of the enhanced diffusion of substrates and reagents through the interfaces favored by the scF phase; (ii) the long term stability of the catalytic systems, which also contributes to the improvement of the final productivity, as the use of an appropriate immobilization strategy facilitates catalyst isolation and reuse; (iii) the development of highly efficient selective or, when applicable, enantioselective chemical transformations. Although the examples reported in the literature and considered in this review are currently confined to a limited number of fields, a significant development in this area can be envisaged for the near future due to the clear advantages of these systems over the conventional ones.

scholarly journals Development of efficient processes under flow conditions based on catalysts immobilized onto monolithic supported ionic liquid-like phases

2009 ◽  
Vol 81 (11) ◽  
pp. 1991-2000 ◽  
Author(s):  
M. Isabel Burguete ◽  
Eduardo García-Verdugo ◽  
Naima Karbass ◽  
Santiago V. Luis ◽  
Victor Sans ◽  
...  
Keyword(s):  
Supercritical Fluids ◽  
Immobilized Enzymes ◽  
Pd Nanoparticles ◽  
The Other ◽  
Morphological Properties ◽  
Flow Conditions ◽  
Catalytic Systems ◽  
Supported Ionic Liquid ◽  
Basic Catalysts ◽  
Catalytically Active

The introduction of imidazolium subunits into polystyrene-divinylbenzene (PS-DVB) polymers enables the preparation of a variety of catalytic systems. Those include the stabilization of catalytically active Pd nanoparticles (PdNPs), immobilized enzymes, and basic catalysts. The use of monolithic supports having the appropriate morphological properties is greatly advantageous for the development of efficient catalytic processes under flow conditions based on those systems. On the other hand, the combination of those supported catalytic systems and flow conditions can be further implemented, in terms of green chemistry, by the substitution of the use of traditional solvents by environmentally friendly conditions such as the use of supercritical fluids (SCFs).

scholarly journals Electrodeposition of palladium-dotted nickel nanowire networks as a robust self-supported methanol electrooxidation catalyst

2021 ◽  
Author(s):  
Tim Boettcher ◽  
Sasho Stojkovikj ◽  
Prashant Khadke ◽  
Ulrike Kunz ◽  
Matthew T. Mayer ◽  
...  
Keyword(s):  
Supported Catalysts ◽  
High Mass ◽  
Potential Cycling ◽  
Free Standing ◽  
Term Stability ◽  
Long Term Stability ◽  
Mass Activity ◽  
Nickel Nanowire ◽  
Nanowire Networks

Abstract Mass activity and long-term stability are two major issues in current fuel cell catalyst designs. While supported catalysts normally suffer from poor long-term stability but show high mass activity, unsupported catalysts tend to perform better in the first point while showing deficits in the latter one. In this study, a facile synthesis route towards self-supported metallic electrocatalyst nanoarchitectures with both aspects in mind is outlined. This procedure consists of a palladium seeding step of ion track-etched polymer templates followed by a nickel electrodeposition and template dissolution. With this strategy, free-standing nickel nanowire networks which contain palladium nanoparticles only in their outer surface are obtained. These networks are tested in anodic half-cell measurements for demonstrating their capability of oxidising methanol in alkaline electrolytes. The results from the electrochemical experiments show that this new catalyst is more tolerant towards high methanol concentrations (up to $${5}\,\hbox{mol}\,\hbox{L}^{-1}$$ 5 mol L - 1 ) than a commercial carbon supported palladium nanoparticle catalyst and provides a much better long-term stability during potential cycling. Graphical Abstract

scholarly journals Recyclable Catalysts for Alkyne Functionalization

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3525
Author(s):  
Leslie Trigoura ◽  
Yalan Xing ◽  
Bhanu P. S. Chauhan
Keyword(s):  
Supported Catalysts ◽  
Metal Organic Framework ◽  
Metal Nanoparticle ◽  
Homogeneous Catalyst ◽  
Catalyst Recycling ◽  
Catalytic Systems ◽  
Recyclable Catalysts ◽  
Metal Organic ◽  
Porous Organic Framework ◽  
Organic Framework

In this review, we present an assessment of recent advances in alkyne functionalization reactions, classified according to different classes of recyclable catalysts. In this work, we have incorporated and reviewed the activity and selectivity of recyclable catalytic systems such as polysiloxane-encapsulated novel metal nanoparticle-based catalysts, silica–copper-supported nanocatalysts, graphitic carbon-supported nanocatalysts, metal organic framework (MOF) catalysts, porous organic framework (POP) catalysts, bio-material-supported catalysts, and metal/solvent free recyclable catalysts. In addition, several alkyne functionalization reactions have been elucidated to demonstrate the success and efficiency of recyclable catalysts. In addition, this review also provides the fundamental knowledge required for utilization of green catalysts, which can combine the advantageous features of both homogeneous (catalyst modulation) and heterogeneous (catalyst recycling) catalysis.

scholarly journals Hydrogen-Free Deoxygenation of Bio-Oil Model Compounds over Sulfur-Free Polymer Supported Catalysts

2020 ◽  
Vol 7 (1) ◽  
pp. 29-36
Author(s):  
Antonina A. Stepacheva ◽  
Mariia E. Markova ◽  
Yury V. Lugovoy ◽  
Kirill V. Chalov ◽  
Mikhail G. Sulman ◽  
...  
Keyword(s):  
Supercritical Fluids ◽  
Aromatic Compounds ◽  
Supported Catalysts ◽  
Major Product ◽  
Hypercrosslinked Polystyrene ◽  
Model Compounds ◽  
Transportation Fuel ◽  
Novel Approach ◽  
Bio Oil ◽  
Hydrogen Donors

AbstractHydrotreatment of bio-oil oxygen compounds allows the final product to be effectively used as a liquid transportation fuel from biomass. Deoxygenation is considered to be one of the most promising ways for bio-oil upgrading. In the current work, we describe a novel approach for the deoxygenation of bio-oil model compounds (anisole, guaiacol) using supercritical fluids as both the solvent and hydrogen-donors. We estimated the possibility of the use of complex solvent consisting of non-polar n-hexane with low critical points (Tc = 234.5 ºC, Pc = 3.02 MPa) and propanol-2 used as H-donor. The experiments were performed without catalysts and in the presence of noble and transition metals hydrothermally deposited on the polymeric matrix of hypercrosslinked polystyrene (HPS). The experiments showed that the presence of 20 vol. % of propanol-2 in n-hexane results in the highest (up to 99%) conversion of model compounds. When the process was carried out without a catalyst, phenols were found to be a major product yielding up to 95 %. The use of Pd- and Co-containing catalyst yielded 90 % of aromatic compounds (benzene and toluene) while in the presence of Ru and Ni cyclohexane and methylcyclohexane (up to 98 %) were the main products.

scholarly journals Synthesis of a Novel Series of Cu(I) Complexes Bearing Alkylated 1,3,5-Triaza-7-phosphaadamantane as Homogeneous and Carbon-Supported Catalysts for the Synthesis of 1- and 2-Substituted-1,2,3-triazoles

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2702
Author(s):  
Ivy L. Librando ◽  
Abdallah G. Mahmoud ◽  
Sónia A. C. Carabineiro ◽  
M. Fátima C. Guedes da Silva ◽  
Carlos F. G. C. Geraldes ◽  
...  
Keyword(s):  
Aqueous Medium ◽  
Sodium Azide ◽  
Supported Catalysts ◽  
Cycloaddition Reaction ◽  
Water Soluble ◽  
Terminal Alkynes ◽  
One Pot ◽  
Catalytic Systems ◽  
Immobilized Catalyst ◽  
High Yields

The N-alkylation of 1,3,5-triaza-7-phosphaadamantane (PTA) with ortho-, meta- and para-substituted nitrobenzyl bromide under mild conditions afforded three hydrophilic PTA ammonium salts, which were used to obtain a new set of seven water-soluble copper(I) complexes. The new compounds were fully characterized and their catalytic activity was investigated for the low power microwave assisted one-pot azide–alkyne cycloaddition reaction in homogeneous aqueous medium to obtain disubstituted 1,2,3-triazoles. The most active catalysts were immobilized on activated carbon (AC), multi-walled carbon nanotubes (CNT), as well as surface functionalized AC and CNT, with the most efficient support being the CNT treated with nitric acid and NaOH. In the presence of the immobilized catalyst, several 1,4-disubstituted-1,2,3-triazoles were obtained from the reaction of terminal alkynes, organic halides and sodium azide in moderate yields up to 80%. Furthermore, the catalyzed reaction of terminal alkynes, formaldehyde and sodium azide afforded 2-hydroxymethyl-2H-1,2,3-triazoles in high yields up to 99%. The immobilized catalyst can be recovered and recycled through simple workup steps and reused up to five consecutive cycles without a marked loss in activity. The described catalytic systems proceed with a broad substrate scope, under microwave irradiation in aqueous medium and according to “click rules”.

Chemical transformations of glucose to value added products using Cu-based catalytic systems

2013 ◽  
Vol 15 (29) ◽  
pp. 12165 ◽  
Author(s):  
Alfonso Yepez ◽  
Antonio Pineda ◽  
Angel Garcia ◽  
Antonio A. Romero ◽  
Rafael Luque
Keyword(s):  
Value Added ◽  
Chemical Transformations ◽  
Catalytic Systems ◽  
Value Added Products

Metal supported catalysts obtained by sol-gel in the hydrosilylation of phenylacetylene with R3SiH organosilanes (R3 = Ph3, Ph2Me, and PhMe2)

2000 ◽  
Vol 78 (11) ◽  
pp. 1491-1495 ◽  
Author(s):  
Rafael Jiménez ◽  
Juan Manuel López ◽  
Jorge Cervantes
Keyword(s):  
Specific Activity ◽  
Supported Catalysts ◽  
Sol Gel ◽  
Synthetic Route ◽  
Catalytic Systems ◽  
Hydrosilylation Reaction ◽  
Solid Catalysts ◽  
Sol Gel Process ◽  
Cis And Trans ◽  
Inorganic Matrices

The hydrosilylation reaction of phenylacetylene, generated on the surface of solid catalysts (such as Pt and Ru) supported on inorganic matrices such as MgO obtained by the sol-gel process, yields vinylsilanes as the main products. The products' distribution, specific activity, and turnover reactions were determined for the case of the hydrosilylation reaction of PhC = CH with R3SiH (R = Ph3, Ph2Me, and PhMe2). For Ph3SiH and Ph2MeSiH, the presence of β-trans and α isomers is observed. Addition of PhMe2SiH to phenylacetylene leads to the formation of β (cis and trans) and α isomers. These catalytic systems provide a new synthetic route to Si—C bond formation.Key words: Vinylsilanes, sol-gel catalysts, hydrosilylation and phenylacetylene.

scholarly journals Green Pathway in Utilizing CO2 via Cycloaddition Reaction with Epoxide—A Mini Review

Processes ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 548 ◽  
Author(s):  
Kunlanan Kiatkittipong ◽  
Muhammad Amirul Amin Mohamad Shukri ◽  
Worapon Kiatkittipong ◽  
Jun Wei Lim ◽  
Pau Loke Show ◽  
...  
Keyword(s):  
Supported Catalysts ◽  
Metal Organic Framework ◽  
Sustainable Use ◽  
Cycloaddition Reaction ◽  
Cyclic Carbonate ◽  
Organic Salt ◽  
Catalytic Systems ◽  
Carbonate Production ◽  
Use Of Resources ◽  
Salen Complexes

Carbon dioxide (CO2) has been anticipated as an ideal carbon building block for organic synthesis due to the noble properties of CO2, which are abundant renewable carbon feedstock, non-toxic nature, and contributing to a more sustainable use of resources. Several green and proficient routes have been established for chemical CO2 fixation. Among the prominent routes, this review epitomizes the reactions involving cycloaddition of epoxides with CO2 in producing cyclic carbonate. Cyclic carbonate has been widely used as a polar aprotic solvent, as an electrolyte in Li-ion batteries, and as precursors for various forms of chemical synthesis such as polycarbonates and polyurethanes. This review provides an overview in terms of the reaction mechanistic pathway and recent advances in the development of several classes of catalysts, including homogeneous organocatalysts (e.g., organic salt, ionic liquid, deep eutectic solvents), organometallic (e.g., mono-, bi-, and tri-metal salen complexes and non-salen complexes) and heterogeneous supported catalysts, and metal organic framework (MOF). Selection of effective catalysts for various epoxide substrates is very important in determining the cycloaddition operating condition. Under their catalytic systems, all classes of these catalysts, with regard to recent developments, can exhibit CO2 cycloaddition of terminal epoxide substrates at ambient temperatures and low CO2 pressure. Although highly desired conversion can be achieved for internal epoxide substrates, higher temperature and pressure are normally required. This includes fatty acid-derived terminal epoxides for oleochemical carbonate production. The production of fully renewable resources by employment of bio-based epoxy with biorefinery concept and potential enhancement of cycloaddition reactions are pointed out as well.

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