2022 patents

  • 3 patent applications

 

2022 publications

Ru(III) single site solid micellar catalyst for selective aqueous phase hydrogenation of carbonyl groups in biomass-derived compounds

Q. Wang, S. Santos, C. A. Urbina-Blanco, W. Zhou, Y. Yang, M. Marinova, S. Heyte, T.-R. Joelle, O. Ersen, W. Baaziz, O. V. Safonova, M. Saeys, V. V. Ordomsky, Applied Catalysis B: Environmental, (2022) 300, 120730.

Abstract

Catalytic processes in water have a lower environmental impact, cost, and toxicity than in organic solvents. Considering the high content of water in biomass, it would be natural to use aqueous phase catalytic technology for the production of valuable products. However, in the aqueous phase, most metal-based catalysts suffer from low activity, low selectivity and deactivation due to metal oxidation and leaching. In this paper, we propose a solid micellar Ru catalyst (Ru(III)@MCM) based on single-site Ru(III) species stabilized by cetyltrimethylammonium (CTA+) surfactant and immobilized in the walls of MCM-41 for the selective aqueous phase hydrogenation of carbonyl groups. This catalyst demonstrates exceptional selectivity, activity, and stability in comparison with conventional metallic catalysts. DFT modeling suggests that the reaction proceeds via heterolytic dissociation of hydrogen, forming a Ru-Hydride species, and subsequent hydride transfer to the carbonyl group. Water plays a key role in avoiding product inhibition.

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Multiphase microreactors based on liquid-liquid and gas-liquid dispersions stabilized by colloidal catalytic particles

D. Dedovets, Q. Li, L. Leclercq, V. Nardello-Rataj, J. Leng, S. Zhao, M. Pera-Titus, Angew. Chem. Int. Ed., (2022), 61, e202107537.

Abstract

Pickering emulsions, foams, bubbles, and marbles are dispersions of two immiscible liquids or of a liquid and a gas stabilized by surface-active colloidal particles. These systems can be used for engineering liquid–liquid–solid and gas–liquid–solid microreactors for multiphase reactions. They constitute original platforms for reengineering multiphase reactors towards a higher degree of sustainability. This Review provides a systematic overview on the recent progress of liquid–liquid and gas–liquid dispersions stabilized by solid particles as microreactors for engineering eco-efficient reactions, with emphasis on biobased reagents. Physicochemical driving parameters, challenges, and strategies to (de)stabilize dispersions for product recovery/catalyst recycling are discussed. Advanced concepts such as cascade and continuous flow reactions, compartmentalization of incompatible reagents, and multiscale computational methods for accelerating particle discovery are also addressed.

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Pickering interfacial catalysis for aerobic alcohol oxidation in oil foams

S. Zhang, D. Dedovets, A. Feng, K. Wang, M. Pera-Titus, J. Am. Chem. Soc., (2022), 144, 4, 1729-1738.

Abstract

Oil foams stabilized by surface-active catalytic particles bearing fluorinated chains and Pd nanoparticles allowed fast and efficient aerobic oxidation of a variety of aromatic and aliphatic alcohols compared to bulk catalytic systems at ambient O2 pressure. High foam stability was achieved at low particle concentration (<1 wt %) provided that the contact angle locates in the range 41°–73°. The catalytic performance was strongly affected by the foaming properties, with 7–10 times activity increase in pure O2 compared to nonfoam systems. Intermediate foam stability was required to achieve good catalytic activity, combining large interfacial area and high gas exchange rate. Particles were conveniently recycled with high foamability and catalytic efficiency maintained for at least seven consecutive runs.

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Organic foams stabilized by Biphenyl-bridged organosilica particles

A. Feng, D. Dedovets, Y. Gu, S. Zhang, J. Sha, X. Han. and M. Pera-Titus, Journal of Colloid and Interface Science, (2022), 617, 171-181.

Abstract

Hypothesis

Can surface-active particles be designed à la carte just by incorporating functional groups mimicking the structure of the solvent and gas? This is based on the idea that, to achieve good foamability, the particle wettability needs to be finely tuned to adjust the liquid-particle and gas-particle surface tensions. In practice, could particles containing phenyl rings and alkyl chains assemble at the air–liquid interface and stabilize foams based on aromatic solvents?

Experiments

A library of organosilica particles was prepared by sol–gel synthesis using aromatic organosilane precursors. The particles were characterized by TGA, FTIR and 13C/29Si MAS NMR. The foaming properties were studied after hand shaking and high-speed homogenization. The influence of particle wettability and solvent properties on foam formation was systematically investigated. A comparison was carried out between biphenyl-bridged particles and various stabilizers on foamability in benzyl alcohol.

Findings

Biphenyl-bridged particles could stabilize foams in aromatic solvents with a high foam volume fraction up to 96% using Ultra-Turrax. The presence of biphenyl rings and short alkyl chains was crucial for foamability. Organic foams were prepared for aromatic solvents with intermediate surface tension (35–44 mN m−1) and contact angle in the range 32–53°. Biphenyl-bridged particles outperformed polytetrafluoroethylene and fluorinated surfactants in benzyl alcohol.

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Oil foams stabilized by POSS/organosilica particle assemblies: application for aerobic oxidation of aromatic alcohols

S. Zhang, D. Dedovets, M. Pera-Titus, Journal of Materials Chemistry A, (2022), 10, 9997-10003.

Abstract

A novel amphiphilic polyhedral oligomeric silsesquioxane (POSS) with surfactant-like behavior was synthesized. By combining this new POSS, used as a frother, with surface-active catalytic organosilica particles, used as a stabilizer, we designed a dual particle system able to generate foams in pure organic solvents. Tunable foamability and foam stability were achieved in a variety of organic solvents by simply adjusting the POSS concentration. As a result, the catalytic activity was drastically boosted in the aerobic oxidation of pure aromatic alcohols under 1 bar O2 pressure. Particles were conveniently recycled with high foamability and the catalytic efficiency was maintained for at least 7 consecutive runs.

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Heterogeneously-catalyzed competitive hydroarylation/hydromination of norbornene with aniline in the presence of Aquivion® ionomer

G. Peng, A. Humblot, R. Wischert, K. de Oliveira Vigier, Marc Pera-Titus, F. Jérôme, Molecular Catalysis, (2022), 525, 112368.

Abstract

The hydroarylation of alkenes with aniline is a reaction of high interest, in particular for the manufacture of polyurethanes. This reaction has been mostly investigated in the presence of homogeneous catalysts. So far, heterogeneous catalysts have been scarcely reported for this reaction, mainly due to their inherent low activity and deactivation during the course of the reaction. Here we report the catalytic performance of Aquivion® ionomer, a perfluorinated solid acid polymer, in the hydroarylation of norbornene with aniline. We show that Aquivion® ionomer was robust and can be recycled for at least 6 runs without any decrease of its catalytic performances. Our results also highlight that Aquivion® ionomer improves the propensity of aniline to react through its aromatic ring, thus yielding a higher proportion of hydroarylation products as compared to other tested homogeneous and heterogeneous catalysts.

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Self-assembly of Symmetric Double Chain Surfactants Derived from Internal Ketone in an Aqueous System

X. Li, B. Hong, R. Schwiedernoch, S. Streiff, Y. Xu, Industrial & Engineering Chemistry Research, (2022), 61, 7275-7283.

Abstract

Double chain surfactants present specific benefits in various applications, such as the enhanced oil recovery and fabric care due to their relatively high packing parameter, which leads to the easier formation of the lamellar microstructure. A series of double chain quaternary cationic ammonium surfactants and amphoteric surfactant (IKD-CAT DiCn, IKD-diquat DiCn with n = 11, 13, 15, and IKD-dibetaine DiC15) have been designed and synthesized in Solvay. The physicochemical properties of these surfactants were studied in this work in order to understand their self-assembly during the applications. Critical micelle concentration and the lyotropic liquid crystals as a function of concentration was investigated with various techniques, such as surface tension-meter, polarizing optical microscopy, and small-angle X-ray scattering. In general, the hydrophilic group structure determines the aggregation evolution patterns and the specific phase concentration range depends on the hydrophobic chain length. A multilayer vesicle aggregation was formed at low concentration and only lamellar phase exists in the phase diagram for IKD-CAT. Besides the lamellar phase, the hexagonal and cubic phases were also observed in IKD-diquat solutions as the concentration was increased.

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Design of Two-Dimensional Heteropolyacid-Covalent Organic Frameworks Composite Materials for Acid Catalysis

T. Gao, Z. Yan, V. Ordomsky, S. Paul, ChemCatChem, (2022), e202101450.

Abstract

Covalent organic frameworks (COFs) is a rapidly developing field in material chemistry. However, COFs still have very limited applications due to the absence of functional groups. In this work, we demonstrate the efficient way for the synthesis of crystalline composite based on phosphotungstic acid and 2D imine CIN-1 type of COF. Heteropolyacid behaves as structure directing agent and it is stabilized between the layers of COF. The composite material shows a layered-sheet arrangement of large imine network layers with sizes up to 1.5 μm. Owing to the strong interaction of heteropolyacid with COF, the resultant material shows high activity and stability with no leaching during acid-catalyzed esterification reaction.

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Foams Stabilized by AquivionTM PFSA: Application to Interfacial Catalysis for Cascade Reactions

A. Fen, D. Dodevets, S. Zhang, J. Sha, R. Schwiedernoch, J. Gao, Y. Gu, M. Pera-Titus, Advanced Materials Interfaces, (2022), 9, 19, 2200380.

Abstract

Foams are attractive platforms for engineering gas–liquid–solid catalytic microreactors with enhanced triphasic contact. In this study, the foaming properties of surface-active AquivionTM perfluorosulfonic acid resin (AquivionTM PFSA) are unraveled. Stable aqueous and non-aqueous foams are prepared driven by hydrogen bond interactions between AquivionTM PFSA and protic solvents (e.g., benzyl alcohol, aniline, water). In light of these unique properties, a catalytic foam system for one-pot cascade deacetalization–hydrogenation reactions is designed. As proof of concept, benzaldehyde dimethyl acetal is converted into benzyl alcohol with 84% overall yield at room temperature in a foam system in the presence of AquivionTM PFSA and Pd/SiO2 catalysts, whereas the yield is halved in a non-foam system. The enhanced reaction efficiency is attributed to a marked increase in interfacial area of the foam system and preferential location of catalytic acid centers at the gas–liquid interface..

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2021 patents

  • 7 patent applications

 

2021 publications

Quinone Shuttling Impels Selective Electrocatalytic Alcohol Oxidation: A Hydrogen Bonding-Directed Electrosynthesis

L. Zhang, A. Grimaud, R. Schwiedernoch, W. Y. Hernández, V. Ordomsky, N. Naghavi, Journal of Electroanalytical Chemistry, 903, (2021), 115820.

Abstract

Today development of efficient catalytic systems for selective oxidation of alcohols to aldehydes remains not only a major concern in basic chemistry research but also a significant challenge for the chemical industry. One promising green and sustainable approach to increase the selectivity as well as waste reduction and to minimize the use of toxic and/or hazardous substances is the development of selective electro-catalytic acceptorless dehydrogenation method. By that, it will be possible to facilitate catalyst recovery and reutilization as well as producing only hydrogen as the by-product. Quinones as principal redox-active moieties within natural organic materials play a key role in electron-transport processes of biological systems. Herein, by taking the oxidation of furfuryl alcohol (FA) in dimethyl sulfoxide (DMSO) as a model reaction, 14 quinone derivatives from 3 families (benzoquinones (BQs), naphthoquinones (NQs), and anthraquinones (AQs)) have been surveyed as a hydrogen acceptor mediators. We demonstrate that, only for three-member ring quinones such as 9,10-anthraquinone-2,6-disulfonic acid (AQDS), which are stable during electrocatalysis, a significant increase of the selectivity to furfural with addition of AQDS is achieved. The effect is assigned to strong intermolecular interaction between FA and quinone dianion (Q2−) with selective transformation to aldehyde its regeneration to quinone and hydrogen production over cathode surface. This study assesses and validates the potential of quinones as electrocatalytic hydrogen acceptor mediators to impel the selective oxidation of alcohol to aldehydes.

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Direct aerobic oxidation of monoalcohol and diols to acetals using tandem Ru@MOF catalysts

S. Zhang, J. P. H. Li, J. Zhao, D. Wu, B. Yuan, W. Y. Hernandez, W. J. Zhou, T. He, Y. Yu, Y. Yang, V. Ordomsky, T. Li, Nano Research, (2021), 14, 479-485.

Abstract

The aerobic oxidation of monoalcohols and diols to acetals is an important academic and industrial challenge for the production of fine chemicals and intermediates. The existing methods usually rely on a two-step process in which alcohols are first oxidized to aldehydes over metal catalysts (Ru, Pt, Pd) and then acetalized using acids. Due to the instability of aldehydes, how to avoid over-oxidation to their respective carboxylic acids and esters is a long-standing challenge. For this reason, certain non-conjugated dialdehydes have never been successfully produced from diol oxidation. Hereby we report a Ru@metal-organic framework (MOF) tandem catalyst containing ultra-fine Ru nanoparticles (< 2 nm) for direct alcohol to acetal conversion of monoalcohol and diols with no formation of carboxylic acids. Mechanistic study reveals that the presence of Lewis acid sites in the MOF work in concert with Ru active sites to promptly convert aldehydes to acetals thereby effectively suppressing the formation of over-oxidation byproducts.

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Dual Metal–Acid Pd-Br Catalyst for Selective Hydrodeoxygenation of 5-Hydroxymethylfurfural (HMF) to 2,5-Dimethylfuran at Ambient Temperature

D. Wu, S. Zhang, W. Y. Hernández, W. Baaziz, O. Ersen, M. Marinova, A. Y. Khodakov, V. V. Ordomsky, ACS Catal., (2021), 11, 1, 19-30.

Abstract

Supported metal catalysts have found broad applications in heterogeneous catalysis. In the conventional bifunctional catalyst, the active metal sites are associated with the metal nanoparticles, while the acid sites are usually localized over the oxide support. Herein, we report a novel type of supported metal bifunctional catalyst, which combined the advantages of the promotion and bifunctionality. The catalyst was designed by the pretreatment of supported palladium catalysts with bromobenzene. The promotion with bromine creates Brønsted acid sites, which are localized directly on the surface of metal nanoparticles. An intimacy between metal and acid functions in this bifunctional catalyst generates unique catalytic properties in hydrodeoxygenation of 5-hydroxymethylfurfural to dimethylfuran, occurring with the yield up to 96% at ambient temperature under 5 bar of H2. The catalyst exhibits stable catalytic performance.

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Lignin Compounds to Monoaromatics: Selective Cleavage of C-O Bonds over a Brominated Ruthenium Catalyst

D. Wu, Q. Wang, O. V. Safonova, D. V. Peron, W. Zhou, Z. Yan, M. Marinova, A. Y. Khodakov, V. V. Ordomsky, Angew. Chem. Int. Ed., (2021), 60, 12513-12523.

Abstract

The cleavage of C-O linkages in aryl ethers in biomass-derived lignin compounds without hydrogenation of the aromatic rings is a major challenge for the production of sustainable mono-aromatics. Conventional strategies over the heterogeneous metal catalysts require the addition of homogeneous base additives causing environmental problems. Herein, we propose a heterogeneous Ru/C catalyst modified by Br atoms for the selective direct cleavage of C-O bonds in diphenyl ether without hydrogenation of aromatic rings reaching the yield of benzene and phenol as high as 90.3 % and increased selectivity to mono-aromatics (97.3 vs. 46.2 % for initial Ru) during depolymerization of lignin. Characterization of the catalyst indicates selective poisoning by Br of terrace sites over Ru nanoparticles, which are active in the hydrogenation of aromatic rings, while the defect sites on the edges and corners remain available and provide higher intrinsic activity in the C-O bond cleavage.

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Surface molecular imprinting over the supported metal catalysts for size-dependent selective hydrogenation reactions

D. Wu, B. Walid, B. Gu, N. Marinova, W. Y. Hernandez, W. Zhou, E. I. Vovk, O. Ersen, O. V. Safanova, A. Addad, N. Nuns, A. Y. Khodakov, V. V. Ordomsky, Nature Catalysis, (2021), 4, 595-606.

Abstract

Molecular imprinting of polymer matrices enables the creation of template-shaped cavities with high affinity for molecules of given shape and size. Here we introduce a surface molecular imprinting strategy to control the hydrogenation selectivity of various aromatic molecules over a supported palladium catalyst. This strategy involves the sequential adsorption over the metal surface of an aromatic template molecule followed by poisoners, resulting in the formation of non-poisoned active islands of predetermined shape and size. Because of steric constraints, these active islands exhibit high selectivity in the chemical conversion of aromatic molecules that correspond in size and shape to the templates. The elaborated strategy enables a practical application relevant to selective hydrogenation and removal of carcinogenic benzene from mixtures of aromatics.

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Solid micellar Ru single-atom catalysts for the water-free hydrogenation of CO2 to formic acid

Q. Wang, S. Santos, C. A. Urbina-Blanco, W. Y. Hernández, M. Impéror-Clerc, E. I. Vovk, M. Marinova, O. Ersen, W. Baaziz, O. V. Safonova, A. Y. Khodakov, M. Saeys, V. V. Ordomsky, Applied Catalysis B: Environment, (2021), 290, 120036.

Abstract

The catalytic hydrogenation of CO2 to formic acid is one of the most promising pathways towards a renewable hydrogen-storage system. The reaction is usually performed in aqueous phase in the presence of basic molecules over homogeneous or heterogeneous catalysts, generating relatively dilute formate solutions (<1 M).
The newly designed solid micellar Ru single-atom catalyst enables efficient and stable water-free CO2 hydrogenation to formate under mild reaction conditions. Concentrated formate solutions (up to 4 M) are produced directly from the hydrogenation of carbon dioxide in water-free tertiary amine. In the catalyst, Ru(III) single sites are incorporated into the walls of MCM-41 during hydrolysis creating a solid micelle structure. The presence of the CTA+ surfactant in the pores of MCM-41 stabilizes the Ru sites and prevents catalyst deactivation. DFT modelling suggests that the reaction proceeds via heterolytic hydrogen splitting, forming a Ru-H species and subsequent hydride transfer to CO2.

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A Combined Experimental-Theoretical Study on Diels-Alder Reaction with Bio-Based Furfural: Towards Renewable Aromatics

I. Scodeller, K. De Oliveira Vigier, E. Muller, C. Ma, F. Guegan, R. Wischert, F. Jerome, ChemSusChem, (2021), 14, 313-323.

Abstract

The synthesis of relevant renewable aromatics from bio-based furfural derivatives and cheap alkenes is carried out by using a Diels-Alder/aromatization sequence. The prediction and the control of the ortho/meta selectivity in the Diels-Alder step is an important issue to pave the way to a wide range of renewable aromatics, but it remains a challenging task. A combined experimental-theoretical approach reveals that, as a general trend, ortho and meta cycloadducts are the kinetic and thermodynamic products, respectively. The nature of substituents, both on the dienes and dienophiles, significantly impacts the feasibility of the reaction, through a modulation on the nucleo- and electrophilicity of the reagents, as well as the ortho/meta ratio. We show that the ortho/meta selectivity at the reaction equilibrium stems from a subtle interplay between charge interactions, favoring the ortho products, and steric interactions, favoring the meta isomers. This work also points towards a path to optimize the aromatization step.

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Hydroamination of non-activated alkenes with ammonia: a holy grail in catalysis

S. Streiff, F. Jerome, Chem. Soc. Rev., (2021), 50, 1512-1521.

Abstract

Alkyl amines represent an important class of chemicals with multiple applications in our daily life. Among the different routes to alkyl amines, the catalytic hydroamination of alkenes with amines is of high interest mainly because it occurs in a 100% atom-economical fashion. To circumvent thermodynamic limitations, activated alkenes or activated amines are essentially employed in such reactions. To date, the catalytic hydroamination of cheap and abundant non-activated (linear) alkenes with ammonia, the simplest amine, remains an unsolved reaction by catalysis. This tutorial review covers the advances reported so far in the intermolecular hydroamination of non-activated linear alkenes with simple alkyl amines, with special interest in ammonia. Focusing on thermodynamics, catalysis and emerging technologies, we aim at providing new perspectives to look at this challenging reaction from a different point of view. In particular, we highlight that the generation of amino radicals from NH3 using "physics activation" is a potential source of inspiration to (i) reduce energy barriers and (ii) reverse the regioselectivity to complete anti-Markovnikov addition.

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Highly selective Ru/HBEA catalyst for the direct amination of fatty alcohols with ammonia

L. Fang, Z. Yan, J. Wu, A. Bugaev, C. Lamberti, M. Pera-Titus, Applied Catalysis B: Environmental, (2021), 286, 119942.

Abstract

The present study describes the synthesis of primary amines from long-chain fatty alcohols and ammonia using supported ruthenium catalysts over different acid supports, including a variety of zeolites with different topologies and Si/Al ratios. The morphology, acidity and location of ruthenium in the catalysts was studied in detail by combining XRD, BET, HR-TEM, NH3-TPD, octylamine-TPD, H2-TPR, XPS, EXAFS / XANES, 27Al MAS NMR and TGA. In particular, Ru/HBEA (Si/Al = 25) with 5 wt% Ru afforded more than 90 % conversion and 90 % selectivity to 1-octylamine in the liquid-phase amination reaction of 1-octanol with ammonia at 180 °C in a batch reactor. The high selectivity of Ru/HBEA (Si/Al = 25) can be explained by the presence of Brønsted / Lewis acid centers with medium strength in the proximity of ruthenium nanoparticles. The catalyst was further tested in a pre-pilot continuous stirred-tank reactor (2 L) with flash separation of 1-octylamine. In this configuration, a steady 92 % selectivity of octylamine was obtained at 87 % 1-octanol conversion during 120 h on steam. The catalyst kept its integrity during the reaction.

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Rational design of bifunctional hierarchical Pd/SAPO-5 for the synthesis of tetrahydrofuran derivatives from furfural

L. Gao, I. Miletto, C. Ivaldi, G. Paul, L. Marchese, S. Coluccia, F. Jiang, E. Gianotti, M. Pera-Titus, Journal of Catalysis, 397 (2021), 397, 75–89.

Abstract

The one-pot aldol condensation/crotonization reaction between furfural and methyl isobutyl ketone (MIBK), followed by hydrogenation with molecular H2, was implemented for preparing tetrahydrofuran derivatives. To this aim, we developed a robust Pd/HPSAPO-5 catalyst based on the crystalline silico-aluminophosphate SAPO-5 with hierarchical porosity and optimized silicon content. The hierarchical HPSAPO-5 catalyst was synthesized using a bottom-up method starting from pre-synthesized MCM-41, with the surfactant (CTAB) inside the mesopores, serving both as Si source and mesoporogen. NH3-TPD and FT-IR spectroscopy of adsorbed probe molecules combined with solid-state 1H MAS NMR were used to assess the nature, strength and accessibility of the acid sites. The structural and textural properties of the catalysts were investigated using X-ray diffraction (XRD) and N2 adsorption. HR-TEM was used to assess the dispersion and location of Pd nanoparticles on HPSAPO-5. The spent catalyst could be restored and reused after calcination.

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Efficient hydrogenation of aliphatic amides to amines over vanadium-modified rhodium supported catalyst

A. Pennetier, W. Y. Hernadez, B. T. Kusema, S. Streiff, Applied Catalysis A, General, (2021), 624, 118301.

Abstract

This work presents a highly efficient catalytic hydrogenation system developed for the selective transformation of tertiary N,N-dimethyldodecanamide and secondary azepan-2-one amides to the corresponding amines. Industrial hydrogenation catalysts Pd/Al2O3, Pt/Al2O3 and Rh/Al2O3 were modified with vanadium (V) or molybdenum (Mo) species as oxophilic centres. The modified catalysts were prepared by deposition of V or Mo precursor on supported catalysts via impregnation method. The catalysts were characterized by ICP-OES, XRD, XPS, H2-TPR, FTIR, CO-chemisorption, TEM, SEM-EDX and TGA. Modified Rh-V/Al2O3 catalyst displayed the best performance affording high yield and selectivity > 95 % to the desired tertiary and secondary amines at moderate reaction conditions of T < 130 °C and PH2 < 50 bar. The strong synergistic interaction and proximity of hydrogenation Rh0 sites and oxophilic Vδ+ sites in the bimetallic Rh-V/Al2O3 catalyst were determined to be beneficial for the selective dissociation of Cdouble bondO bond of the carboxamides into the desired amines.

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Single-reactor tandem oxidation–amination process for the synthesis of furan diamines from 5-hydroxymethylfurfural

J. Sha, B. T. Kusema, W. Zhou, Z. Yan, S. Streiff, M. Pera-Titus, Green Chem., (2021), 23, 7093-7099.

Abstract

We present an efficient and intensified single-reactor tandem process accessing a library of secondary furan diamines from HMF. The process comprises two in situ consecutive steps: (1) aerobic oxidation of HMF to DFF, and (2) reductive amination of DFF to diamines. The reactor was operated using a mechanical mixture of 5%Ru/C + 5%Pd/C catalysts with more than 87% overall yield of diamines. With these results, a bifunctional (Ru + Pd)/C catalyst was engineered with comparable results to the mechanical mixture.

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Identification of active catalysts for the acceptorless dehydrogenation of alcohols to carbonyls

T. Wang, J. Sha, M. Sabbe, P. Sautet, M. Pera-Titus, C. Michel, Nature Communications, (2021), 12, 5100.

Abstract

Acceptorless dehydrogenation into carbonyls and molecular hydrogen is an attractive strategy to valorize (biobased) alcohols. Using 2-octanol dehydrogenation as benchmark reaction in a continuous reactor, a library of metal-supported catalysts is tested to validate the predictive level of catalytic activity for combined DFT and micro-kinetic modeling. Based on a series of transition metals, scaling relations are determined as a function of two descriptors, i.e. the surface binding energies of atomic carbon and oxygen. Then, a volcano-shape relation based on both descriptors is derived, paving the way to further optimization of active catalysts. Evaluation of 294 diluted alloys but also a series of carbides and nitrides with the volcano map identified 12 promising candidates with potentially improved activity for alcohol dehydrogenation, which provides useful guidance for experimental catalyst design. Further screening identifies β-Mo2N and γ-Mo2N exposing mostly (001) and (100) facets as potential candidates for alcohol dehydrogenation.

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Conversion of ammonia to hydrazine induced by high frequency ultrasound

A. Humblot, L. Grimaud, A. Allavena, P. N. Amaniampong, K. De Oliveira Vigier, T. Chave, S. Streiff, F. Jérôme, Angew. Chem. Int. Ed., (2021), 60, 25230.

Abstract

Hydrazine is a chemical of utmost importance in our society, either for organic synthesis or energy use. The direct conversion of NH3 to hydrazine is highly appealing, but it remains a very difficult task because the degradation of hydrazine is thermodynamically more feasible than the cleavage of the N−H bond of NH3. As a result, any catalyst capable of activating NH3 will thus unavoidably decompose N2H4. Here we show that cavitation bubbles, created by ultrasonic irradiation of aqueous NH3 at a high frequency, act as microreactors to activate and convert NH3 to NH species, without assistance of any catalyst, yielding hydrazine at the bubble–liquid interface. The compartmentation of in-situ-produced hydrazine in the bulk solution, which is maintained close to 30 °C, advantageously prevents its thermal degradation, a recurrent problem faced by previous technologies. This work also points towards a path to scavenge .OH radicals by adjusting the NH3 concentration.

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Pivotal role of H2 in the isomerisation of isosorbide over Ru/C catalyst

H. Hu, A. Ramzan, R. Wischert, F. Jérôme, C. Michel, K. de Oliveira Vigier, M. Pera-Titus, Catal. Sci. Technol., (2021), 11, 7973-7981.

Abstract

Isosorbide isomerisation is a known reaction that can proceed over Ru and Ni-based heterogeneous catalysts. As a rule, an exogenous H2 pressure (40–100 bar) is required, even though H2 does not participate stoichiometrically in the reaction. By marrying experiments with DFT computations, we ascribe the role of H2 in isosorbide isomerisation to a coverage effect on the catalyst surface. We demonstrate the possibility of conducting the reaction at a low H2 pressure either in the presence of an inert gas to increase H2 solubility in an underlying solvent or using 2-propanol as a hydrogen donor. This might benefit the economy and safety of a potential industrial process.

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Heterogenization of complexes by encapsulation in solid micelles for aqueous phase catalysis

Q. Wang, W. Zhou, S. Heyte, T.-R. Joelle, M. Marinova, A. Addad, S. Rouziere, P. Simon, M. Capron, V. V. Ordomsky, Chem. Mater., (2021), 33, 21, 8501–8511.

Abstract

The heterogenization of homogeneous complexes to combine the advantages of both approaches in catalysis has been attracting researchers and industries over the last decades. The common approaches are based on the grafting of homogeneous catalysts or their encapsulation in small-sized porous matrixes, which often affect the state of the complex and the catalytic performance. Herein, we propose a new approach of heterogenization of homogeneous complexes such as tris(triphenylphosphine)ruthenium dichloride by encapsulation in solid micelles during the synthesis of MCM-41 with subsequent narrowing of the pores by recrystallization. The prepared materials demonstrate stable catalytic performance without leaching of the complex at the activities comparable to the pure complex in the hydrogenation reactions. The key advantage of this technology is that it allows performing catalysis in an aqueous phase at complex insoluble conditions. The solid micelles provide a soluble environment for the complex with high intrinsic activity regardless of the solvent in the reactor.

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Selective acid-catalyzed hydroarylation of nonactivated alkenes with aniline assisted by hexafluoroisopropanol

G. Peng, A. Humblot, R. Wischert, K. de Oliveira Vigier, F. Jiang, M. Pera-Titus, F. Jérôme, J. Org. Chem., (2021), 86, 24, 17896–17905.

Abstract

The catalytic hydroarylation of nonactivated alkenes with aniline is a reaction of high interest, aiming at providing C-functionalized aniline derivatives that are important precursors for the fabrication of polyurethanes. However, this reaction remains a longstanding goal of catalysis, as it requires one to simultaneously address two important goals: (1) the very low reactivity of nonactivated alkenes and (2) control of the hydroarylation/hydroamination selectivity. As a result, the hydroarylation of aniline is mostly restricted to activated alkenes (i.e., featuring ring strain, conjugation, or activation with electron-donating or -withdrawing groups). Here we show that the combination of bismuth triflate and hexafluoroisopropanol (HFIP) leads to the formation of highly active catalytic species capable of promoting the hydroarylation of various nonactivated alkenes, such as 1-octene, 1-heptene, and 1-undecene, among others, with aniline with high selectivity (71–92%). Through a combined experimental and computational investigation, we propose a reaction pathway where HFIP stabilizes the rate-determining transition state through a H-bond interaction with the triflate anion, thus assisting the acid catalyst in the hydroarylation of nonactivated alkenes. From a practical point of view, this work opens a catalytic access to C-functionalized aniline derivatives from two cheap and abundant feedstocks in a 100% atom-economical fashion.

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