2013 patents

  • 10 patent applications

 

2013 publications

Directed Self-Assembly of Block Copolymers on Sparsely Nanopatterned Substrates

Abstract

Using real-space self-consistent field theory calculations (SCFT), directed self-assembly of block copolymers was explored on sparsely nanopatterned substrates. In this study, the lamellar structure forming block copolymers are confined between two surfaces. The top surface is strictly neutral, and the bottom one is periodically patterned with neutral interspacing (nanopattern), which forms a sparsely nanopatterned substrate. The dimension of nanopatterns is commensurate with periods of lamellar structure of the block copolymers self-assembling in bulk. By systematically varying the film thickness and interspacing between nanopatterns, the density multiplication of nanopattern in the film was investigated, and a variety of nanostructures not available in bulk (nonbulk structures) were observed.

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In situ crystallization of b-oriented MFI films on plane and curved substrates coated with a mesoporous silica layer

Abstract

A simple and reproducible method is presented for preparing b-oriented MFI films on plane (disc) and curved (hollow fiber) supports by in situ hydrothermal synthesis. A mesoporous silica (sub-)layer was pre-coated on the supports by dip coating followed by a rapid thermal calcination step (973 K during 1 min) to reduce the number of grain boundaries while keeping the hydrophilic behavior of silica. The role of the silica sub-layer is not only to smoothen the substrate surface, but also to provide a silica source to promote the nucleation and growth of zeolite crystals via a heterogeneous nucleation mechanism (zeolitization), and adsorb zeolite moieties generated in the synthesis solution via a homogeneous nucleation mechanism. A monolayer of b-oriented MFI crystals was obtained on both supports after 3 h synthesis time with a moderate degree of twinning on the surface.

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Catalytic etherification of glycerol with short chain alkyl alcohols in the presence of Lewis acids

Abstract

Here we report the homogeneously-catalyzed etherification of glycerol with short chain alkyl alcohols. Among the large variety of Brønsted and Lewis acids tested, we show here that metal triflates are not only the most active but are also capable of catalyzing this reaction with an unprecedented selectivity. In particular, in the presence of Bi(OTf)3, the targeted monoalkylglyceryl ethers were obtained with up to 70% yield. Although tested Brønsted acids were also capable of catalyzing the etherification of glycerol with alkyl alcohols, they were found however less active and less selective than Bi(OTf)3. By means of counter experiments, we highlighted that the high activity and selectivity of Bi(OTf)3 may rely on a synergistic effect between Bi(OTf)3 and triflic acid, a Brønsted acid that can be released by in situ glycerolysis of Bi(OTf)3. The scope of this methodology was also extended to other polyols and, in all cases, the monoalkylpolyol ethers were conveniently obtained with fair to good yields.

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Cyclic glyceryl sulfate: a simple and versatile bio-based synthon for the facile and convergent synthesis of novel surface-active agents

Abstract

In the frame of biomass valorization, a novel and simple cyclic glyceryl sulfate was efficiently prepared in two steps from glycerol. It was shown to react efficiently with primary, secondary as well as tertiary amines to afford either the corresponding anionic or zwitterionic surface-active agents.

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Selective oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran over intercalated vanadium phosphate oxides

Abstract

The selective oxidation of 5-hydroxymethylfurfural (5-HMF) to 2,5-diformylfuran (DFF) was studied over vanadium phosphate oxide (VPO)-based heterogeneous catalysts in the liquid phase. The selectivity to DFF was highly increased when using intercalated vanadium phosphate oxides under mild conditions (1 atm of oxygen, 110 °C) in an aromatic solvent. We found that the length of the intercalated ammonium alkyl chain had no clear influence on the catalytic performances, and a maximum yield of 83% could be achieved over C14VOPO4 and C14VOHPO4 after 6 h of reaction. Recycling of the catalyst was successfully performed, and we further obtained some insights in the reaction pathway: while the desired oxidation reaction indeed proceeded over the catalyst, the formation of by-products was linked to the presence of free radicals in solution.

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8‐Aminoquinoline: A Powerful Directing Group in Metal‐Catalyzed Direct Functionalization of CH Bonds

Abstract

Chelate me if you can: Over the last decade, strategies for the functionalization of both Curn:x-wiley:14337851:media:ANIE201303556:tex2gif-inf-1H and Curn:x-wiley:14337851:media:ANIE201303556:tex2gif-inf-2H bonds have witnessed an increasing use of a simple, yet powerful directing group, 8‐aminoquinoline (in blue). This auxiliary is very efficient in a wide range of metal‐mediated reactions, and can be readily removed to afford the desired carboxylic acids or corresponding derivatives.

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Selectivity enhancement in the aqueous acid-catalyzed conversion of glucose to 5-hydroxymethylfurfural induced by choline chloride

Abstract

In this work we wish to show that choline chloride (ChCl), a cheap and safe quaternary ammonium salt industrially produced at a few thousand tons per year through a 100% atom economy process, is capable of enhancing the selectivity of metal chlorides such as AlCl3, FeCl3 and CuCl2 in the aqueous tandem isomerization/dehydration of glucose to HMF. Under optimized conditions, 70% yield of HMF was obtained in a water/methylisobutylketone (MIBK) biphasic system which is a competitive yield to those traditionally obtained in imidazolium-based ionic liquids in the presence of hazardous chromium salts. By means of counter experiments, we show that the selectivity enhancement is optimal for a ChCl content of 50 wt% in water. At higher loading of ChCl, strong molecular interaction occurs between ChCl and HMF making the extraction of HMF from the aqueous phase difficult with MIBK, thus enhancing side reactions of HMF with water and hexoses to unwanted products. Interestingly, this process can be transposed to the direct conversion of cellulose to HMF which is an even more challenging reaction. In this case, we show that combination of FeCl3 with AlCl3 allowed cellulose to be converted to HMF with 49% yield in a one pot reaction. From the viewpoint of sustainable chemistry, this work shows noticeable advantages such as the use of (1) water as a solvent, (2) ChCl as a cheap and safe additive, (3) cheap and naturally abundant metals (Al, Fe, and Cu) and (4) renewable raw materials.

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Effect of selective nanoparticles on phase separation of copolymer–nanoparticle composites confined between two neutral surfaces

Abstract

Using Monte Carlo simulation, we investigated the phase separation of copolymer–nanoparticle composites confined between two neutral surfaces. The incorporated nanoparticles are selective to the copolymer blocks, being repulsive to one block and attractive to the other. We constructed a series of phase diagrams for copolymer nanocomposites phase separated under varied film thicknesses. With the increase of concentration of nanoparticles, a morphological transition from lamellae to perforated lamellae, cylinders, and spheres was observed in the films. The effect of system parameters on the formation and orientation of these structures was studied in detail. We also investigated the evolution of the configuration of the chains and their composed blocks, as a function of concentration and selectivity strength of the nanoparticles.

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2014 patents

  • 12 patent application

 

2014 publications

Nitrile Synthesis through Catalyzed Cascades Involving Acid–Nitrile Exchange

Abstract

Irreversible acid–nitrile exchange reactions using both glutaronitrile and (phenylsulfonyl)acetonitrile may be catalyzed by Lewis acids. Whereas a cyclization towards imides displaces the equilibria in the reaction with dinitriles, a decarboxylation step is involved when using the (phenylsulfonyl)acetonitrile.

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Combination of Pd/C and Amberlyst-15 in a single reactor for the acid/hydrogenating catalytic conversion of carbohydrates to 5-hydroxy-2,5-hexanedione

Abstract

Here we show that combination of Pd/C and Amberlyst-15 in a single reactor allowed fructose and inulin to be converted to 5-hydroxy-2-5-hexanedione, a valuable chemical platform, in a one-pot process.

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Palladium/Carbon Dioxide Cooperative Catalysis for the Production of Diketone Derivatives from Carbohydrates

Abstract

The one‐pot production of industrially valuable diketone derivatives from carbohydrates is achieved through a bifunctional catalytic process. In particular, Pd/C‐catalyzed hydrogenation of HMF in water and under CO2 affords 1‐hydroxypentane‐2,5‐dione with up to 77 % yield. The process is also eligible starting from fructose and inulin, affording 1‐hydroxyhexane‐2,5‐dione with 36 % and 15 % yield, respectively. The key of the process is reversible in situ formation of carbonic acid, which is capable of assisting Pd/C during the hydrogenation reaction by promoting the dehydration of carbohydrates and the ring‐opening of furanic intermediates. Interestingly, by changing the reaction medium from H2O to a H2O/THF mixture (1:9), it is possible to switch the selectivity of the reaction and to produce 2,5‐hexanadione with 83 % yield. Within the framework of sustainable chemistry, reactions presented in this report show 100 % carbon economy, involve CO2 to generate acidity, require water as a solvent, and are conducted under rather low hydrogen pressures (10 bar).

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Enhanced H2 Uptake of n-Alkanes Confined in Mesoporous Materials

Abstract

The hydrogen uptake in hybrid sorbents consisting of n-alkane solvents confined in mesoporous silica aerogel is measured at different temperatures from 273 to 313 K and pressures up to 40 bar. An apparent “oversolubility” effect is observed as the H2 uptake in the hybrid sorbents is much larger than that in bulk solvents. The H2 uptake in the hybrid sorbents is found to increase with increasing temperature, which suggests that the flexibility and conformation of n-alkane molecules confined in the aerogel play a crucial role; high-entropy (disordered) alkane configurations lead to the creation of numerous cavities which make it possible to solubilize a larger number of H2 molecules. This departs from adsorption-driven solubility effects for which the number of solubilized molecules decreases with increasing temperature. For a given temperature and pressure, it is found that the number of solubilized H2 molecules per unit volume increases with decreasing alkane chain length. Such an effect, which is observed for both the bulk alkanes and the alkanes confined in the silica aerogel, can be rationalized by considering the number density of CHx (x = 2 or 3) groups; for a given temperature, the latter number density decreases with decreasing alkane chain length so that the free volume available to solubilize H2 molecules increases.

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Photocatalytic oxidation of ethanol using paper-based nano-TiO2 immobilized on porous silica: A modelling study

Abstract

A new model coupling the convection–diffusion equations for mass transfer and the Kubelka–Munk model for UV penetration is presented for describing the photocatalytic degradation of volatile organic compounds in titania-loaded papers. The model has been validated using a broad collection of ethanol degradation data measured on 10 different paper sheets incorporating titania-anchored hollow silica into the cellulose fibers with a wide spectra of basis weights and TiO2/SiO2 loadings, and operated at different ethanol concentrations, superficial velocities, UV intensities and configuration modes (i.e. counter- and co-current). Only two parameters were fitted, namely the intensity-independent kinetic constant and the adsorption constant of ethanol over TiO2. The simulated UV intensity profiles suggest a strong UV attenuation within the paper thickness, limiting the irradiated TiO2 to less than 30% of the available loading. Both the counter- and co-current configuration modes show comparable results in terms of photocatalytic activity, but with marked differences in terms of concentration and diffusive flow patterns. As a result, matching the general assumptions in the literature, mass transfer in co-current configuration approaches to a continuous stirred-tank reactor under Perfect Mixture, most of the photocatalytic activity being localized near the paper inlet. Our simulations reflect potential improvements in terms of activity by mitigating UV attenuation (especially UV scattering) in the papers.

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Tunable Catalysts for Solvent-Free Biphasic Systems: Pickering Interfacial Catalysts over Amphiphilic Silica Nanoparticles

Abstract

Stabilization of oil/oil Pickering emulsions using robust and recyclable catalytic amphiphilic silica nanoparticles bearing alkyl and propylsulfonic acid groups allows fast and efficient solvent-free acetalization of immiscible long-chain fatty aldehydes with ethylene glycol.

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The impact of natural polymer derivatives on sheet erosion on experimental loess hillslope

Abstract

Macromolecular polymers can effectively improve soil structure, increase soil penetration and control runoff and erosion on hillslopes. Simulated rainfall experiments on a bare soil investigated the impact of natural polymer derivatives (NPD) on soil properties and the characteristics of runoff and sediment yield of sheet erosion on experimental loessial hillslopes. A control (without NPD) and three concentrations of polymers (1, 3 and 5 g/m2) were tested at rainfall intensities of 1, 1.5 and 2 mm/min and a slope gradient of 15°. NPD effectively altered the onset, volume and sediment content of the runoff. Higher concentrations of NPD provided earlier onsets, lower depth and lower sediment contents of the runoff. Compared with control, cumulative runoffs decreased by 49–68%, 61–70% and 69–79% at concentrations of 1, 3 and 5 g/m2 NPD, respectively, while cumulative erosion modulus decreased by 31–37%, 39–47%, 56–61%, respectively. Additionally, NPDs significantly increased the shear strength and the composition of aggregates from soil surface. Shear strength was 2.71, 3.24 and 4.01 times higher at 1, 3 and 5 g/m2, respectively, than in the controls. The percent mass of aggregates >0.25 mm increased to 52.5%, 62.65% and 73.0% from 8.9% in the control at the three respective concentrations. More research is needed to confirm the utility of NPDs in helping to control sheet erosion.

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Intrinsic Flexibility of the Zeolitic Imidazolate Framework ZIF‐7 Unveiled by CO2 Adsorption and Hg Intrusion

Abstract

ZIF‐7, built as an assembly of ZnII centers and benzimidazolate ligands, shows prominent S‐shaped isotherms upon CO2 adsorption that can be attributed to sorbate‐induced gate‐opening phenomena involving a narrow‐to‐large pore phase transition. This peculiar sorption pattern can be captured via the formulation of thermodynamic isotherms, providing a direct enthalpic and entropic view of the gate‐opening process. Relying on such an approach, an energy barrier with preferential enthalpic nature for CO2 adsorption/desorption in the gate‐opening region could be unveiled. Moreover, the elastic energy involved during the gate‐opening process was revisited to 1.4–2.8 kJ mol−1 of solid in the temperature range 273–323 K, matching the value measured by isostatic compression of a ZIF‐7_lp sample filled with DMF and showing a dominant entropic contribution.

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Photocatalytic paper based on sol–gel titania nanoparticles immobilized on porous silica for VOC abatement

Abstract

A new composite paper with high photocatalytic performance has been successfully manufactured by introducing titania-anchored porous silica into cellulose fibres. The silica particles with an average size of 700 nm were synthesized via CaCO3 templating and further employed as support to grow titania nanoparticles (5.2 nm) by sol–gel synthesis with variable weight ratios. The photocatalytic materials have been characterized using various techniques including BET, XRD, Raman spectroscopy, SEM and TEM + EDX + ED microscopies. The composite TiO2/SiO2 particles have been further introduced in bulk paper to generate highly active photocatalytic TiO2-loaded papers. The activity of the papers has been demonstrated in the room-temperature degradation of ethanol (50–200 ppm) under UV irradiation, showing a comparable activity to that of commercial TiO2-coated papers. The effect of the main textural variables during papermaking on the photocatalytic performance are discussed in detail.

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Catalytic Amination of Biomass‐Based Alcohols

Abstract

Can I borrow hydrogen? Direct amination of biomass‐derived platform alcohols can be efficiently performed through the borrowing hydrogen mechanism, offering high activity and selectivity at low‐to‐moderate temperatures. Unlike nucleophilic substitution, the catalyst behaves as a tandem system involving the temporary removal of H2 from the reaction medium.

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Pickering Interfacial Catalysts for solvent-free biomass transformation: Physicochemical behavior of non-aqueous emulsions

Abstract

A key challenge in biomass conversion is how to achieve valuable molecules with optimal reactivity in the presence of immiscible reactants. This issue is usually tackled using either organic solvents or surfactants to promote emulsification, making industrial processes expensive and not environmentally friendly. As an alternative, Pickering emulsions using solid particles with tailored designed surface properties can promote phase contact within intrinsically biphasic systems. Here we show that amphiphilic silica nanoparticles bearing a proper combination of alkyl and strong acidic surface groups can generate stable Pickering emulsions of the glycerol/dodecanol system in the temperature range of 35–130 °C. We also show that such particles can perform as Pickering Interfacial Catalysts for the acid-catalyzed etherification of glycerol with dodecanol at 150 °C. Our findings shed light on some key parameters governing emulsion stability and catalytic activity of Pickering interfacial catalytic systems. This understanding is critical to pave the way toward technological solutions for biomass upgrading able to promote eco-efficient reactions between immiscible organic reagents with neither use of solvents nor surfactants.

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Highly Selective Liquid-Phase Oxidation of Cyclohexane to KA Oil over Ti-MWW Catalyst: Evidence of Formation of Oxyl Radicals

Abstract

Various types of Ti-containing zeolites, i.e., Ti-MWW, TS-1, Ti-MOR, and Ti-BEA, have been evaluated as candidates for the liquid-phase oxidation of cyclohexane using t-butyl hydroperoxide (TBHP, 7–8 wt %) as model oxidant. Ti-MWW zeolite displayed the highest activity for cyclohexanol and cyclohexanone (KA oil) with an overall selectivity higher than 90% at 80 °C, making this catalyst a candidate of choice for industrial KA oil production by deperoxidation of cyclohexyl hydroperoxide. The effect of the reaction temperature, reaction time, catalyst amount, and catalyst stability on Ti-MWW was surveyed in detail. The Ti-MWW catalyst showed a stable performance and could be recycled at least four times without detectable Ti leaching and loss of structural stability. The active sites for cyclohexane oxidation appeared to be located near external 12-ring cups in the Ti-MWW framework as suggested by a series of position-selective poisoning tests with tripropyl- and triphenylamine, impelling cyclohexane diffusion within the internal 10-ring channels. EPR experiments supported by DFT calculations suggested the coexistence of both Ti(IV)-OO• (peroxyl) and Ti(IV)-O• (oxyl) species generated through bimolecular pathways, implying simultaneously (SiO)3Ti(OOtBu) species and tBuOOH. The catalytic activity was strongly inhibited in the presence of alkenes, leading to the preferential formation of the epoxidation product with no detectable formation of radicals. Notably, this is the first time that oxyl species have been detected particularly with the help of DFT calculations. Predicted differences of g tensors between peroxyl and oxyl species at various hydration levels in the presence of cyclohexane were consistent with the EPR spectra.

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Highly selective direct amination of primary alcohols over a Pd/K-OMS-2 catalyst

Abstract

A new Pd-substituted octahedral molecular sieve (Pd/K-OMS-2) catalyst has been prepared for the direct amination of alcohols with primary amines operating under the borrowing hydrogen mechanism. The catalyst offered full conversion and high selectivity toward N-benzylaniline in the model alkylation reaction of aniline with benzyl alcohol at mild temperature (160 °C) for 3 h with neither production of the tertiary amine nor toluene. Pd/K-OMS-2 performed as a tandem tri-functional catalyst, first oxidizing benzyl alcohol to benzaldehyde, behaving as a Lewis acid for imine formation, and finally reducing the imine to the secondary amine. The catalyst was characterized in depth using BET, XRD, H2-TPR, XPS, FTIR, TEM, TGA/DTG, and ICP-AES / EDX to elucidate the nature of the active sites. The unexpectedly high performance of the Pd/K-OMS-2 catalyst can be ascribed, at least partially, to the in situ generation of a very active, selective and partially recyclable Pd-substituted/supported hausmannite phase (i.e., Pd/Mn3O4) in the early stage of the reaction with a high density of surface oxygen moieties. We argue about a possible role of a Pd(IV)/Pd(II) redox pump for exchanging hydrogen during the amination reaction.

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Porous Inorganic Membranes for CO2 Capture: Present and Prospects
Formation of Acrylates from Ethylene and CO2 on Ni Complexes: A Mechanistic Viewpoint from a Hybrid DFT Approach

Abstract

The most challenging step in the production of acrylates from ethylene and CO2 mediated by transition-metal complexes is the release of the acrylate from the metallalactone intermediate formed by coupling of ethylene and CO2. Recently, methyl acrylate formation was achieved from nickelalactones by using methyl iodide (MeI) as the electrophile, and the yield was tuned with different amine and phosphine ligands. Modeling organometallic catalysts with such large ligands accurately is a challenge for computational chemistry. A hybrid approach has been designed here by coupling the double hybrid XYG3 and the hybrid B3LYP exchange correlation functionals, using the extended ONIOM scheme. This approach was then applied to explore the role of the MeI electrophile for the formation of methyl acrylate from the initial nickelalactone complex and to rationalize the effect of the ligands on the yield of methyl acrylate. We show that the choice of ligand has little effect on the main productive pathway. However, it has a significant influence on side reactions, which compete with the productive pathway and are detrimental to methyl acrylate formation. Finally, the need for a very large overstoichiometry of MeI for a good yield of methyl acrylate is explained by the lower polarity of MeI, which avoids the stabilization of nonproductive intermediates. The nature of the limiting intermediates has been validated by comparing calculated and experimental vibrational spectra.

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