2015 patents

  • 6 patent applications

 

2015 publications

Hexamethylenediamine (HMDA) from fossil- vs. bio-based routes: an economic and life cycle assessment comparative study

Abstract

Hexamethylenediamine (HMDA) is one of the key intermediates in the preparation of nylon 6-6 by polycondensation with adipic acid. Currently, the most used commercial process for HMDA manufacture proceeds via the hydrogenation of adiponitrile in ammonia, which is in turn produced by the hydrocyanation of butadiene. In this paper, we explore three alternative bio-based paths for HMDA production starting from high fructose syrup made from maize and potato-derived starch and using 5-(hydroxymethyl)furfural (HMF) as intermediate building block. Different routes have been compared using a combined economic and life-cycle assessment study including a sensitivity analysis on potential key parameters. Overall, our study reflects a higher economic benefit and a lower environmental impact of the benchmark fossil-based route. As for the environmental impact, the most advantageous of the three bio-based routes could present benefits in terms of CO2 footprint when the carbon sink is taken into account, but at the expense of a higher impact on terrestrial, marine and freshwater eutrophication. Possible process improvements to make bio-based routes affordable for HMDA production are proposed as an attempt to draw general rules for process eco-design.

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Glycerol/Dodecanol Double Pickering Emulsions Stabilized by Polystyrene‐Grafted Silica Nanoparticles for Interfacial Catalysis

Abstract

Polystyrene‐grafted silica nanoparticles bearing sulfonic acid centers and with tunable amphiphilic properties were designed to perform the biphasic etherification reaction of glycerol with dodecanol at the interface of Pickering emulsions. By optimizing the hydrophobic properties of the particles, double Pickering emulsions could be generated allowing a facilitated diffusion of glycerol and dodecanol into the microenvironment near the acid centers.

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Homogeneously-acid catalyzed oligomerization of glycerol

Abstract

Here we report the screening of various homogeneous acid catalysts in the oligomerization of glycerol at 150 °C. Under optimized conditions, a mixture of oligoglycerol with an average degree of oligomerization of 3.4 was obtained at a glycerol conversion of 80%. At such a conversion, the selectivity to oligoglycerols was higher than 90%. Oligoglycerols were then successfully alkylated, offering an attractive route to valuable molecules (biosurfactants or hydrotropes).

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Preparation of bio-based surfactants from glycerol and dodecanol by direct etherification

Abstract

In this paper, we studied an original synthetic strategy to prepare bio-based surfactants by direct solvent-free etherification of glycerol with dodecanol using heterogeneous interfacial acidic catalysts dubbed Pickering Interfacial Catalysis. The conversion of dodecanol could be achieved to 60–71% with limited production of didodecyl ether (DE) as the main side product. The selectivity of the final product, alkylpolyglycerylether (AGEM), could be pushed to >80% with a water removal process at 150 °C, as a mixture of monolauryl polyglyceryl ethers, multilauryl polyglyceryl ethers and multilauryl cyclicpolyglyceryl ethers. AGEM could be isolated with a suitable work-up and was fully characterized by GC (MS), HPLC, SFC/HRMS, etc. The physicochemical properties of these new surfactants were evaluated, as well as their laundry performances. This solvent-free direct etherification process paves the way towards new value-added applications of glycerol.

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Pickering Interfacial Catalysis for Biphasic Systems: From Emulsion Design to Green Reactions

Abstract

Pickering emulsions are surfactant‐free dispersions of two immiscible fluids that are kinetically stabilized by colloidal particles. For ecological reasons, these systems have undergone a resurgence of interest to mitigate the use of synthetic surfactants and solvents. Moreover, the use of colloidal particles as stabilizers provides emulsions with original properties compared to surfactant‐stabilized emulsions, microemulsions, and micellar systems. Despite these specific advantages, the application of Pickering emulsions to catalysis has been rarely explored. This Minireview describes very recent examples of hybrid and composite amphiphilic materials for the design of interfacial catalysts in Pickering emulsions with special emphasis on their assets and challenges for industrially relevant biphasic reactions in fine chemistry, biofuel upgrading, and depollution.

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Novel route for the synthesis of 8-oxa-3-azabicyclo[3.2.1]octane: One-pot aminocyclization of 2,5-tetrahydrofurandimethanol catalyzed by Pt/NiCuAlOx

Abstract

2,5-Tetrahydrofurandimethanol (THFDM) was selectively transformed into 8-oxa-3-azabicyclo[3.2.1] octane (OABCO), a valuable building block for the synthesis of bioactive molecules, via one-pot aminocyclization with ammonia catalyzed by Pt/NiCuAlOx. Under optimized conditions (200 °C, 6–16 h, 0.5 MPa hydrogen, 0.4 MPa ammonia), the OABCO yield reached 58% with 100% THFDM conversion.

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Amphiphilic Titanosilicates as Pickering Interfacial Catalysts for Liquid-Phase Oxidation Reactions

Abstract

Monodispersed amphiphilic zeolite/mesosilica composite material TS-1@KCC-1 (TK), which could stabilize Pickering emulsions for the benzene/H2O2 system, has been synthesized, and its physicochemical properties have been investigated in detail. The amphiphilic TK catalyst displayed a higher catalytic activity under Pickering interfacial catalysis (PIC) than under phase-boundary catalysis (PBC) and conventional reaction conditions in the hydroxylation of benzene by hydrogen peroxide without cosolvent and under static conditions. Under optimized conditions, a TS-1@KCC-1 catalyst grafted with octyl chains (2.42 wt %) could afford an interfacial activity of 1.1 mol (Ti-mol)−1. Moreover, PIC reaction conditions exhibited an excellent thermal stability and good reusability.

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Modeling the HCOOH/CO2 Electrocatalytic Reaction: When Details Are Key

Abstract

Our first principles simulations of the electrooxidation of formic acid over nickel identify the reorientation of the formate intermediate and the desorption of CO2 as the rate‐limiting steps. Although they are not associated with an electron transfer, these barriers are strongly modified when the electrochemical potential is explicitly accounted for and when modeling the influence of the solvent. Hence, such a level of modeling is key to understand the kinetic limitations that penalize the reaction.

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Impacts of electrode potentials and solvents on the electroreduction of CO2: a comparison of theoretical approaches

Abstract

Since CO2 is a readily available feedstock throughout the world, the utilization of CO2 as a C1 building block for the synthesis of valuable chemicals is a highly attractive concept. However, due to its very nature of energy depleted “carbon sink”, CO2 has a very low reactivity. Electrocatalysis offers the most attractive means to activate CO2 through reduction: the electron is the “cleanest” reducing agent whose energy can be tuned to the thermodynamic optimum. Under protic conditions, the reduction of CO2 over many metal electrodes results in formic acid. Thus, to open the road to its utilization as a C1 building block, the presence of water should be avoided to allow a more diverse chemistry, in particular for C–C bond formation with alkenes. Under those conditions, the intrinsic reactivity of CO2 can generate carbonates and oxalates by C–O and C–C bond formation, respectively. On Ni(111), almost exclusively carbonates and carbon monoxide are evidenced experimentally. Despite recent progress in modelling electrocatalytic reactions, determining the actual mechanism and selectivities between competing reaction pathways is still not straight forward. As a simple but important example of the intrinsic reactivity of CO2 under aprotic conditions, we highlight the shortcomings of the popular linear free energy relationship for electrode potentials (LFER-EP). Going beyond this zeroth order approximation by charging the surface and thus explicitly including the electrochemical potential into the electronic structure computations allows us to access more detailed insights, shedding light on coverage effects and on the influence of counterions.

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2016 patents

  • 14 patent applications

 

2016 publications

Direct dehydration of 1,3-butanediol into butadiene over aluminosilicate catalysts

Abstract

The catalytic dehydration of 1,3-butanediol into butadiene was investigated over various aluminosilicates with different SiO2/Al2O3 ratios and pore architectures. A correlation between the catalytic performance and the total number of acid sites and acid strength was established, with a better performance for lower acid site densities as inferred from combined NH3-TPD, pyridine adsorption and 27Al-NMR MAS spectroscopy. The presence of native Brønsted acid sites of medium strength was correlated to the formation of butadiene. A maximum butadiene yield of 60% was achieved at 300 °C over H-ZSM-5 with a SiO2/Al2O3 ratio of 260 with the simultaneous formation of propylene at a BD/propylene selectivity ratio of 2.5. This catalyst further exhibited a slight deactivation during a 102 h run with a decrease in the conversion from 100% to 80% due to coke deposition as evidenced by XPS and TGA-MS, resulting in a 36% loss of the specific surface area.

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Dynamics of Pickering Emulsions in the Presence of an Interfacial Reaction: A Simulation Study

Abstract

Pickering emulsions combining surface-active and catalytic properties offer a promising platform for conducting interfacial reactions between immiscible reagents. Despite the significant progress in the design of Pickering interfacial catalysts for a broad panel of reactions, the dynamics of Pickering emulsions under reaction conditions is still poorly understood. Herein, using benzene hydroxylation with aqueous H2O2 as a model system, we explored the dynamics of benzene/water Pickering emulsions during reaction by dissipative particle dynamics. Our study points out that the surface wettability of the silica nanoparticles is affected to a higher extent by the degree of polymer grafting rather than an increase of the chain length of hydrophobic polymer moieties. A remarkable decline of the oil-in-water (O/W) interfacial tension was observed when increasing the yield of the reaction product (phenol), affecting the emulsion stability. However, phenol did not alter to an important extent the distribution of immiscible reagents around the nanoparticles sitting at the benzene/water interface. A synergistic effect between phenol and silica nanoparticles on the O/W interfacial tension of the biphasic system could be ascertained.

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Microwave‐Assisted Formylations of Weakly Basic Anilines with Methyl Formate Catalyzed by Calcium and Hydrogen Triflimides

Abstract

Catalytic amounts of calcium and hydrogen triflimides [Ca(NTf2)2, HNTf2] were found to be efficient for the solvent‐free formylation of a variety of weakly basic anilines by using cheap and widely available methyl formate as the formylating agent under microwave irradiation. Initial investigations showed that in the case of calcium triflimide, Brønsted acid catalysis was most likely operating. Remarkably, the corresponding calcium triflate and triflic acid were significantly less active.

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Aquivion®–carbon composites via hydrothermal carbonization: amphiphilic catalysts for solvent-free biphasic acetalization

Abstract

One-pot hydrothermal carbonization of polysaccharides (i.e. guar gum or cellulose) with Aquivion® perfluorosulfonic superacid at 180 °C produced new amphiphilic Aquivion®–carbon composites. The materials stabilized dodecyl aldehyde/ethyleneglycol Pickering emulsions, and thus efficiently catalyzed the solvent-free biphasic acetalization reaction under moderate conditions with excellent reusability.

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Direct inference of site strength in basic solids upon CO2 adsorption: enthalpy–entropy compensation effects

Abstract

The adsorption of CO2 coupled to calorimetry is a state-of-the-art technique for characterizing the basic properties of solids. In this paper, we show that the differential heat and entropy curves measured upon CO2 adsorption on a basic solid can be reasonably estimated from a single CO2 isotherm with no need for any independent heat (calorimetric) measurement. Our method relies on two important observations: (1) formulation of generalized F–H–TS thermodynamic isotherms, the former (F) being directly generated from the raw CO2 isotherms, and (2) the presence of unexpected enthalpy–entropy compensation effects upon CO2 adsorption linking the integral enthalpy and entropy of adsorption until saturation for different solids. Our thermodynamic method has been validated using a broad library of basic solids with variable site strength and heterogeneity. Finally, a new scale of basicity is proposed using the parameters fitted from the thermodynamic isotherm (free energy basis) as descriptors of basic strength. This method opens an avenue to the inference of site strength of basic solids without the need for expensive calorimeters.

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A Pd/CeO2 “H2 Pump” for the Direct Amination of Alcohols

Abstract

A Pd/CeO2 catalyst with a prominent reversible H2 storage capacity revealed a high activity and selectivity in the direct amination of benzyl alcohol with aniline and ammonia via the borrowing hydrogen mechanism.

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Heterogeneously-acid catalyzed oligomerization of glycerol over recyclable superacid Aquivion® PFSA

Abstract

This manuscript explores the catalytic activity, selectivity and stability of Aquivion® PFSA PW98 in the oligomerization of glycerol. Aquivion® PFSA PW98 is a solid superacid catalyst with a Hammett acidity function of −12. Furthermore, the perfluorinated structure allows this polymer to stand quite high operating temperature (up to 150–160 °C) without loss in mechanical and chemical integrity which is of huge interest for glycerol conversion. In this context, we discovered that Aquivion® PFSA PW98 was nearly fully selective to oligoglycerols up to 80% conversion of glycerol. The oligomerization degree of oligoglycerol and the regioselectivity of the reaction (linear vs branched and cyclic isomers) were fully analyzed by means of GC and SEC chromatographies. In contrast to conventional solid acid catalysts, Aquivion® PFSA PW98 was found highly robust in glycerol and was sucessfully recycled at least 10 times without apparent decrease in activity or selectivity. A comparison with Nafion NR 50 is also included to shed light on the potential of Aquivion® PFSA PW98 for acid-catalyzed conversion of glycerol.

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Electro-carboxylation of butadiene and ethene over Pt and Ni catalysts

Abstract

Electrochemical synthesis could provide an elegant and efficient means to exploit the largely available C1 building block CO2. The electrocarboxylation of dienes is, in particular, an attractive goal. However, the presently known electrocatalysts are inefficient and not very selective since they work around −2.3 V vs. SHE. In order to identify more active catalysts, we need to better understand the reaction mechanism. In this contribution, we present prototypical experimental results for the electrocarboxylation of 2,3-dimethyl-butadiene on a Ni catalyst and quantify the side-products, namely carbonates, oxalic and formic acid. Together with the extensive, state of the art, first principles investigation of the mechanism at the atomic scale, we reveal a highly activated process around the onset potential of −1.3 V and a change in mechanism at the peak potential of −2.3 V, suggesting that a more active catalyst could be engineered by modifying the morphology in order to facilitate the “chemical” Csingle bondC coupling step.

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Selective synthesis of ethylene oxide through liquid-phase epoxidation of ethylene with titanosilicate/H2O2 catalytic systems

Abstract

Liquid-phase epoxidation of ethylene to ethylene oxide (EO) with H2O2 over various titanosilicate catalysts like Ti-MWW, TS-1, Ti-MOR and Ti-Beta has been investigated. The effects of solvent, catalyst amount, reaction pressure, temperature and time on the catalytic performance of Ti-MWW have been studied in detail. Ti-MWW preferred acetonitrile as a solvent and showed the highest reactivity and EO selectivity among the titanosilicate catalysts investigated. Under optimized reaction conditions, Ti-MWW gave a EO selectivity high as 97.9% as well as a reasonable utilization efficiency of H2O2 of 77.7%. Ti-MWW was gradually deactivated after repeated use in ethylene epoxidation. High-temperature calcination easily recovered the catalytic activity of deactivated Ti-MWW after removing ethylene glycol (EG) and other heavy byproducts with high boiling points that were deposited inside micropores. The issues of molecular dimension and reactivity have also been considered by comparing the epoxidation of linear alkenes with different lengths (C2 to C6) between two representative titanosilicates Ti-MWW and TS-1. Ethylene, with the smallest dynamic diameter but containing electron-deficient Cdouble bondC double bonds, was more difficult to be epoxidized than other alkenes with higher intrinsic activities.

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Selective oxidation of fatty alcohol ethoxylates with H2O2 over Au catalysts for the synthesis of alkyl ether carboxylic acids in alkaline solution

Abstract

In this paper, we report a green and selective route for the direct oxidation of alcohol ethoxylates (AEOs) into alkyl ether carboxylic acids over supported noble metal catalysts using H2O2 as an oxidant in the presence of a base. The catalytic performance of supported Au, Pt and Pd was assessed in the oxidation of AEO7 consisting of C12–C14-alcohol polyethyleneglycol ether with average 7 EO units. Among the different catalysts tested, Au/Al2O3 and Au/TiO2 displayed a yield up to 88% to polyoxyethylene(7) lauryl ether carboxylic acid (AECA6) at 80 °C. The effect of Au particle size, reaction temperature, reaction time, catalyst loading and base amount on the activity, selectivity and stability of Au/Al2O3 was explored in detail. Hydroxyl radicals were generated during the reaction as suggested by a series of poisoning tests using 2,2,6,6-tetramethylpiperidinoxyl and 1,4-benzoquinone as radical scavengers. Au/Al2O3 and Au/TiO2 could only be reused in two consecutive runs, showing a strong deactivation in the third run and beyond due to Au leaching and partial nanoparticle sintering as inferred by combined TEM and ICP-AES analysis. The Au stability could be highly promoted over a bimetallic AuPt/TiO2 formulation, showing a good recyclability and reuse for at least 10 consecutive catalytic cycles.

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