2021 publications

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

Linjie Zhang, Alexis Grimaud, Renate Schwiedernoch, Willinton Hernández, Vitaly Ordomsky, Negar Naghavi, Linjie Zhang, Alexis Grimaud, Renate Schwiedernoch, Willinton Hernández, Vitaly Ordomsky, Negar Naghavi (2021). Available at SSRN: https://ssrn.com/abstract=3885506 or http://dx.doi.org/10.2139/ssrn.3885506

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 and Hydroquione intermediate and its regeneration to quinone and hydrogen 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. W. Zhang, J. P. H. Li, J. P. 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, pp. 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, pp. 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. Engl. (2021), 60, pp. 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 Enciso, W. Zhou, A. Khodakov, V. Ordomsky, Nature Catalysis (2021), 4, pp. 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, Appl. Catal., B (2021), 290, pp. 120036-120045.

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. van Scodeller, K. De Oliveira Vigier, E. Muller, C. Ma, F. Guegan, R. Wischert, F. Jerome, ChemSusChem (2021), 14, pp. 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, pp. 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, Appl. Catal., B (2021), 286, pp. 119942-119953.

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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