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The design of an "H"‐shaped reactor has been studied to satisfy the possibility of using a triphasic medium to transform d‐glucose into 5‐hydroxymethylfurfural (HMF) by a hybrid catalytic process using an immobilized glucose isomerase, allowing the isomerization of D‐glucose to d‐fructose, and a heterogeneous chemical catalyst to catalyze the dehydration of d‐fructose to HMF. The various parameters influencing the transport of d‐fructose within the reactor were studied, namely the difference in pH between the two aqueous phases, the agitation and the quantity of 3,4‐DCPBA/Aliquat336® used to extract and transport continuously the d‐fructose. The pH discrepancy, which must be between 5.0 and 5.5, turns out to be the real driving force behind the extraction of D‐fructose. The D‐Fru/3,4‐DCPBA molar ratio of 1/0.25 allowed the transport of more than 80 % of the D‐fructose initially present and shows that the same molecule of 3,4‐DCPBA is involved at least twice in the transport of D‐fructose and that the 3,4‐DCPBA/Aliquat336® couple performs a turnover within the organic phase. Finally, a HMF production yield of 30.9 % and an isomerization yield of 79.1 % were obtained, illustrating the shift in the isomerization equilibrium made possible by a D‐fructose extraction yield of 96.8 %. [ABSTRACT FROM AUTHOR]

With the development of a strong bioeconomy sector related to the creation of next-generation biorefineries, heterogeneous catalysis is receiving renewed attention. Indeed, catalysis is at the core of biorefinery design, and many new catalysts and catalytic processes are being developed. On the one hand, they are based on knowledge acquired during the last century to efficiently upgrade fossil resources. On the other hand, they take advantage of the opportunity of having new substrates on which novel conversion technologies, derived from recent fundamental advances and new concepts developed in the field of heterogeneous catalysis, can be tested and applied. In this context, there is a global trend for establishing new courses throughout the world to train students and professionals in the bioeconomy/biorefinery sector. Such courses encompass many different fields in a multidisciplinary approach, including agronomy, logistics, life cycle assessment, biotechnologies, process design, economics, and, obviously, chemistry. For the last of these, a specific important role is given to catalysis, and more especially to heterogeneous catalysis. Such courses need to explain the basics of each scientific field involved before giving concrete examples of research/development. Among them, the aforementioned heterogeneous catalysis is an especially complex scientific field in which surface science, spectroscopy, thermodynamics, and other disciplines are intimately interwoven. While many references presenting specific aspects of catalysis can be found, concise documents encompassing all of the angles of this very rich field -- including its most recent developments and prospects, aimed at a readership already trained in chemistry -- are scarce. This paper gives a global and simple "heterogeneous catalysis tour" to explain in a concise way what heterogeneous catalysis is without going into too much detail. The students who would like to know more about some specific aspects will find useful authoritative references in the text, making this paper a good introduction to all aspects of heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

Silica-supported catalysts based on Keggin-type heteropolyacids (HPAs) containing rubidium or cesium as counter cations have been prepared by the impregnation method and evaluated in the selective oxidation of iso butane to methacrolein and methacrylic acid. The catalysts were characterized by various techniques such as XRD, N 2 physisorption, TGA, Raman spectroscopy, H 2 -TPR, and NH 3 -TPD in order to study their thermal stability, structural, and textural properties, acidity and reducibility. It was evidenced that the reducibility of the Keggin type HPAs was improved by supporting the active phase on SiO 2. A loading of 40 wt% was the optimum for the selective oxidation of iso butane (IBAN) to methacrylic acid (MAA). The selectivities to MAA and methacrolein (MAC) at given conversion were increased when Cs+ was used as counter cation compared to Rb+. The same trend was observed for mono- and di-vanado-substituted phosphomolybdic acid, whereby the performance followed the order: CsV 1 /SiO 2 > RbV 1 /SiO 2 > CsV 2 /SiO 2 > RbV 2 /SiO 2. The density of acid sites was correlated to the catalytic activity, which underlines the importance of the acid sites for alkane activation. [Display omitted] • Thermal stability and reducibility of the Keggin type HPAs improved by SiO 2 support. • Increased selectivity to methacrylic acid and methacrolein at given conversion for Cs+ counter cation compared to Rb+. • Density of acid sites directly correlated to the catalytic activity. [ABSTRACT FROM AUTHOR]

Abstract: A series of hydrodesulfurization (HDS) catalysts was prepared by impregnation of Co and Mo on sol–gel B–Al2O3 supports with B/Al ratios of 0, 0.02, 0.04, 0.08, 0.20, 0.32, 0.49, and 0.61. The thiophene HDS and dibenzothiophene (DBT) HDS activities were both maximal for the catalyst with B/Al=0.04, with respective values 70 and 42% higher than those for an industrial reference catalyst. These maxima in HDS activity correlated with the previously reported presence of isolated BO4 surface species. These BO4 species were responsible for a local maximum in the acidity of the B–Al2O3 supports when B/Al=0.04. In contrast, the formation of mixed oxides (A9B2 and A2B) or B2O3 that also resulted in enhanced acidity of the B–Al2O3 supports had a detrimental effect on the HDS activity. The 4,6-dimethyldibenzothiophene (4,6-DMDBT) HDS activity over the CoMo/B–Al2O3 catalysts decreased when the B/Al ratio was increased. This was attributed to the strong direct desulfurization character of the CoMo catalysts supported on the B–Al2O3 supports, because high hydrogenation ability toward the Cbonds is essential prior to sulfur removal from 4,6-DMDBT. The excellent performance in the thiophene and DBT HDS of the CoMo/B–Al2O3 catalysts is particularly useful for ultra-deep HDS of light fractions. [Copyright &y& Elsevier]

The first part of this paper deals with the morphology of the MoS2 phase and its oxide precursor, the MoO3 phase, mainly from a geometrical point of view. After giving a brief review of the literature describing the structure of these compounds, Mo densities in both phases were calculated along various crystallographic planes. Further, using structural models recently proposed by others, Mo densities in MoS2 were also calculated in the case of an epitactic growth on γ-Al2O3 and TiO2 model surfaces. Then, the calculated Mo densities were compared with experimental results (Mo density when HDS activity is maximal) previously obtained for catalysts constituted of MoS2 supported on a low SSA TiO2, a high SSA TiO2 and a conventional γ-alumina. It was suggested that either on alumina or titania the MoS2 phase is growing as (100) MoS2 planes. However, while on the alumina the optimal MoS2 phase might be constituted of dispersed MoS2 slabs covering only a part of the alumina surface (2.9–3.9 Mo atoms/nm2), on titania the optimal MoS2 phase might be constituted of a uniform MoS2 monolayer (5.2 atoms/nm2 for the high SSA titania, which is equal to the Mo density of a perfect MoS2 (100) plane). This difference may originate in the creation of a 'TiMoS' phase enhancing the S atoms mobility over Mo/TiO2-sulfided catalysts. Indeed, while in the case of a γ-alumina carrier the active sites (labile S atoms) are located on the edge of MoS2 slabs making the ratio Moedge/Mototal a crucial parameter for the catalytic performances, in the case of a titania carrier the labile sulfur atoms might be statistically distributed all over the TiMoS active phase. Further, the higher Mo density observed over the high SSA titania (5.2 atoms/nm2) when compared to that over the low SSA titania (4.2 atoms/nm2) was supposedly due to the pH-swing method advantageously used to prepare the former carrier. Indeed, this method allows giving a solid with enhanced mechanical properties providing a good stability to the derived catalysts under experimental conditions. In addition, this TiO2 carrier exhibits a great homogeneity, with a surface structure substantially uniform, which might be adequate for a long-range growth of (100) MoS2 slabs. [ABSTRACT FROM AUTHOR]

Three series of CoMo catalysts (MoO3: 6, 11, 16 wt.%) with various Co/Mo molar ratios were prepared by successive incipient wetness impregnations of a titania sample previously prepared by the pH swing method, which provides a TiO2 carrier with a high SSA (134 m2 g−1) and excellent mechanical properties. DBT HDS activity of the catalysts increased with addition of cobalt up to Co/Mo=0.4 and then decreased for higher ratios, irrespective of the Mo loading. The results of a [35S]DBT HDS method showed that S0, the amount of labile sulfur atoms, increased in parallel with the activity when adding Co up to a molar ratio of 0.4. In contrast, unlike on CoMo/Al2O3 catalysts, only a slight increase in kRE, the H2S release rate constant, was observed upon Co addition. This was due to formation of the TiMoS phase: while formation of Ti一S*一Mo bonds favorably induces an increase in sulfur mobility on Mo/TiO2 catalysts, electronic density on Mo atoms increases, which limits the promoting effect of Co on mobility of Sa sulfur atoms bridged between Mo and Co. Further, while the increase in HDS activity upon Co addition on a uniform MoS2 monolayer on TiO2 was in rather good agreement with the quantitative and kinetics data of the 35S tracer method, over MoS2 slabs on TiO2 this increase was larger than that expected from the results of the 35S tracer method. This was attributed to the presence of □* and □a CUS, i.e. catalytic sites that are not replenished with sulfur, at the steady state. A larger number of □* CUS was present at low Mo wt.% or for low Co/Mo. As these particular catalytic sites are in the form of CUS at the steady state, they are not accounted by the [35S] radiotracer method. This explains the differences observed between the experimental DBT HDS promotion and the promotion deduced from the increase in kRE and S0. [Copyright &y& Elsevier]

Abstract: We systematically monitored the hydrodesulfurization (HDS) activity of dibenzothiophene (DBT) and groups of substituted DBTs present in a SR-LGO over various noble metal catalysts (Ru, Rh, Ru-Rh, Pt, Pd and Pt-Pd) supported on alumina. The catalytic performances were compared to those obtained over a conventional CoMo catalyst. The Pd-based catalysts exhibited excellent HDS performances, especially for desulfurizing the refractory compounds. In particular, the 4,6-dimethyldibenzothiophene (4,6-DMDBT) HDS activity over the Pd or the Pd-Pt catalyst was equivalent to that over the CoMo catalyst. This was attributed to the exceptional hydrogenation (HYD) properties of the Pd-based catalysts, which enable desulfurization of the refractory compounds by considerably minimizing the effect of the steric hindrance due to their substituents. The synergetic effect observed on the bimetallic Pt-Pd system at low temperature for all the sulfur compounds was largely attenuated in the high temperature range, probably due to shifting of the HYD/dehydrogenation equilibrium to dehydrogenation. Despite a much lower metal loading (0.25wt.%), the performances of the Rh catalyst were superior to those of the optimized 16wt.% Ru catalyst. A synergetic effect was observed on the Ru-Rh catalyst, on which the DBT HDS activity was significantly enhanced compared to the activity of each corresponding monometallic catalyst. Further, we recently showed that the use of SiO2 or SiO2-Al2O3 as a support allows higher optimal Rh contents, making the Rh-based HDS catalysts even more promising. In brief, we obtained encouraging results, which showed for instance that the excellent properties of the noble metal catalysts in model HDS reactions are still observed during the HDS treatment of real feeds. [Copyright &y& Elsevier]

Abstract: By combining experimental results and computer simulations, we previously showed that the coordinatively unsaturated sites (CUS) formation over MoS2 is most likely to occur on the MoS2 metallic edge through the departure of an H2S molecule. In the present paper, we aimed at examining the H2S departure from MoS2 catalysts promoted with Co and Ni. The [35S]DBT HDS experiments results showed that over CoMoS/Al2O3 and NiMoS/Al2O3 catalysts, the activation energy of the H2S release reaction is essentially the same with respective values of 7.4 and 7.9kcalmol−1. Considering the H2S departure activation energy in the case of the non-promoted MoS2 surface (10–12kcalmol−1), this result illustrates the synergetic effect between Mo and Co or Ni in terms of CUS regeneration easiness. Further, preliminary computer simulations results showed that for S atoms bridged between Co atoms, a mechanism implying H2S departure from the metallic edge cannot be reasonably envisaged. Moreover, on the sulfur edge the H2S release activation energy is too high (∼13.5kcalmol−1) if we consider experimental results on CoMo/Al2O3 catalysts, but not incompatible with the experimental value obtained over Co/Al2O3 catalysts (ca. 10kcalmol−1), which suggests that the mechanism on the promoted catalysts differs from that on the un-promoted ones. [Copyright &y& Elsevier]

Abstract: A series of CoMo/Al2O3 catalysts was prepared by impregnation on a series of alumina powders synthesized by the sol–gel method with different hydrolysis ratios R (defined as [H2O]/[aluminum-tri-sec-butoxide (ASB)]; R =3,4,…,12,13). The oxide precursors were characterized and subsequently tested in the hydrodesulfurization (HDS) of thiophene, dibenzothiophene (DBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT). Mainly due to their large pore diameters of ca. 6nm, the catalysts prepared from the alumina with hydrolysis ratio R =7–10 showed higher HDS activity compared with the activities of the other prepared catalysts. The effect of the pore diffusional limitation was more significant than expected, due to the ink-bottle shape of the pores of the prepared catalysts with hydrolysis ratio R <8 and R >10. Due to highly dispersed CoMo active phase, the HDS activity of the prepared catalysts with hydrolysis ratio R =8 and 9 for thiophene was similar to that of a reference industrial catalyst that was designed and manufactured for deep HDS of diesel fuel fractions. Furthermore, the HDS activity of the prepared catalysts with hydrolysis ratio R >5 for DBT was higher than that of the reference industrial catalyst. For 4,6-DMDBT, however, the reference industrial catalyst showed higher HDS activity compared with the activities of the prepared catalysts. Relatively high HDS activity was observed for the prepared catalysts with R =9 and 10 with cylindrical pore shape and with a high proportion of strong acid sites. The strong acidity supposedly enhanced the hydrogenation activity of the catalysts that was essential for the HDS of 4,6-DMDBT. [Copyright &y& Elsevier]

The first part of this paper is a short review of the [sup 35]S radioactive tracer methods developed in recent years. Then, the experimental results obtained so far on Mo/Al[sub 2]O[sub 3] catalysts are compared with computer simulation results recently claimed in order to elucidate the coordinatively unsaturated site (CUS) creation/replenishment/ regeneration mechanism over MoS[sub 2] crystallites. The computer simulations allowed us to pre-select thermodynamically acceptable mechanisms among a set of suggested ones. Then, by comparison of the calculated activation energies with the [sup 35]S experiments results we could further validate the most probable mechanism. This mechanism involved the dissociative adsorption of an H[sub 2] molecule on the metallic edge of a MoS[sub 2] crystallite surface with further creation of a CUS by release of one H[sub 2]S molecule in the gas phase. Both laboratory and computer simulated experiments permitted to calculate the activation energy for the H2S liberation reaction. In both cases, this energy was about 10- 12 kcal/mol, confirming the accuracy of the proposed mechanism. Moreover, the calculated activation energy of the rate-limiting step for the creation of one CUS by the proposed mechanism was about 23 kcal/mol, which was also in good agreement with the experimental activation energy of the dibenzothiophene (DBT) hydrodesulphurisation (HDS) reaction (typically about 20- 22 kcal/mol). This correlation indicated that the DBT HDS reaction rate might be intrinsically governed by the CUS formation/replenishment process, i.e. that the vacancy formation process is a crucial parameter in the global HDS reaction mechanism. Nevertheless, in the case of the 4,6-dimethyl DBT (4,6-DMDBT) HDS reaction, the experimental activation energy is higher (approx. 30 kcal/mol), confirming that external parameters induced by the 4,6-DMDBT-specific properties themselves are likely to play an important role in the reaction process, in addition to the ones intrinsic to the catalytic phase. [ABSTRACT FROM AUTHOR]

Sulfidation of CrO3–Al2O3 catalysts (11.1, 16.6 and 22.2 wt.% CrO3) synthesized by incipient wetness impregnation method was monitored by a 35S radioisotope ([35S]H2S) pulse tracer in situ method. This original method permitted us a better understanding of these relatively poorly documented catalytic systems. Experiences confirmed that, in a first step, for temperatures inferior to 400 °C, CrSx species are progressively formed. Then, in a second step for a temperature near 400 °C, formation of Cr2S3 entities is achieved, leading to their decomposition into CrS. This showed that the catalytic phase morphology depends drastically on the sulfidation temperature. Moreover, it was found that the increase in DBT activity with the Cr content previously observed was due to a modification of the nature of the active phase and not to an increase in its quantity. Indeed, whilst the sulfur quantity that accumulated on the catalysts containing 11.1 and 22.2 wt.% CrO3 was almost the same, the DBT HDS activity of the latter was ∼50% higher. [Copyright &y& Elsevier]

The structural and acidic properties of sol–gel prepared alumina powders as catalyst supports were modified by adjusting the hydrolysis ratio, R (i.e. molar ratio of water relative to the alumina precursor, R=[H2O]/[aluminium-tri-sec-butoxide (ASB)]). Structural properties (e.g. porosity) and acidic properties were measured for alumina powders prepared with various R values, from 3 to 13. For R<9 and R>10, first-order particles were closely packed with ink-bottle-type pore structures, whereas for R=9 or 10, first-order particles were loosely packed with a spatial fractal arrangement that yielded pseudo-cylindrical pore structures. In addition, the alumina powders prepared with R=9 or 10 had larger water pore volume and stronger acidity than those with other R values. These properties unique to the powders prepared with R=9 or 10 were ascribed to relatively short Al–O–Al chain lengths that resulted in loose packing of first-order particles. The results here indicate that alumina powders with favorable properties as catalyst supports (e.g. mean pore diameter) can be tailored by selecting the appropriate R in the sol–gel synthesis process. [Copyright &y& Elsevier]

[Display omitted] • The active phase of calcium-based catalysts for glycerol polymerization was investigated. • Ca-glycerolate was identified as being the in situ formed solid active phase. • A mechanism is proposed to explain the in situ formation of calcium glycerolate. • A mechanism is proposed for the polymerization of glycerol catalyzed by Ca-glycerolate. Ca-based catalysts are of strong interest for glycerol polymerization reaction due to their high catalytic performances, their wide availability and the absence of any toxicity. In the present study, we investigated the active phase of CaO, Ca(OH) 2 , CaCO 3 and calcium diglyceroxide used as catalysts for this reaction. The solids were analyzed by XRD, solid-state 13C-NMR and TGA-DSC. XRD evidenced the presence of calcium glycerolate in the spent catalysts when CaO, Ca(OH) 2 and calcium diglyceroxide were used as starting materials. This was corroborated by the TGA-DSC results. Further, the SS NMR results showed that the as-formed calcium glycerolate is a mixture of linear Ca(C 3 H 7 O 3) and cyclic-branched Ca(C 3 H 6 O 3). Moreover, the recycled catalyst issued, e.g. , from CaO was more efficient that the initial catalyst with a glycerol conversion of 47 % (vs. 22 % initially for CaO) and a 70 % (vs. 55 %) selectivity to polyglycerols higher than tetraglycerol at 245 °C after 4 h in the presence of 3.5 mol.% of catalyst. As the main outcome, we have shown that Ca-glycerolate is the actual solid active phase, which is formed in situ from CaO and Ca(OH) 2 playing the role of catalyst precursors. A mechanism involving the dissolution of CaO and Ca(OH) 2 , the formation of Ca-glycerolate and its precipitation followed by crystallization, supported by characterization studies, is proposed. [ABSTRACT FROM AUTHOR]

This study aimed at optimizing the production of glycolic acid from glycerol catalytic oxidation over a silver catalyst supported on a mixed cerium-zirconium oxide, to progress towards the industrialization of a derived process. Optimization of the operating conditions was performed using the response surface methodology. We concluded that the production of glycolic acid depends mainly of glycerol concentration, NaOH/glycerol ratio, catalyst/glycerol ratio, and O2/glycerol ratio. The optimal conditions we found were a temperature of 60 °C, a NaOH/glycerol molar ratio of 2, an O2/glycerol molar ratio of 0.23, and a catalyst/glycerol mass ratio of 0.07. With these optimal conditions, it was possible to increase the glycerol concentration from 0.3 M to 2 M, obtaining an increase in the concentration of glycolic acid in the liquid fraction, from 0.27 mol/L of glycolic acid (with initial glycerol solution 0.3 M) to 0.88 mol/L (with initial solution 2 M), while keeping a 100% glycerol conversion. [ABSTRACT FROM AUTHOR]

Supported gold nanoparticles have proven to be highly effective catalysts for the base-free oxidation of furfural, a compound derived from biomass. Their small size enables a high surface-area-to-volume ratio, providing abundant active sites for the reaction to take place. These gold nanoparticles serve as catalysts by providing surfaces for furfural molecules to adsorb onto and facilitating electron transfer between the substrate and the oxidizing agent. The role of the support in this reaction has been widely studied, and gold–support interactions have been found to be beneficial. However, the exact mechanism of furfural oxidation under base-free conditions remains an active area of research and is not yet fully understood. In this review, we delve into the essential factors that influence the selectivity of furfural oxidation. We present an optimization process that highlights the significant role of machine learning in identifying the best catalyst for this reaction. The principal objective of this study is to provide a comprehensive review of research conducted over the past five years concerning the catalytic oxidation of furfural under base-free conditions. By conducting tree decision making on experimental data from recent articles, a total of 93 gold-based catalysts are compared. The relative variable importance chart analysis reveals that the support preparation method and the pH of the solution are the most crucial factors determining the yield of furoic acid in this oxidation process. [ABSTRACT FROM AUTHOR]

This study explores the performances of nickel‐based materials for the dry reforming of methane (DRM), an important process for hydrogen and syngas productions. Ni nanoparticles are issued from porous phyllosilicate phase exolution under reducing conditions (in situ or ex situ). Phyllosilicate precursors were obtained by deposition/precipitation with urea onto SBA‐15 porous silica, with metal loading up to 40 wt.%. Reaction was performed at 600–700 °C. The successful formation and stabilization of highly dispersed nanoparticles (2–6 nm) is revealed, even for highly loaded formulations (20 wt.% and 40 wt.%). In DRM‐700 (CH4/CO2=1, 20 % CH4, 480,000 mL gcat−1 h−1) the formulation at 20 wt.% metal loading (Ni_20 %) activated during reaction affords 50 % and 65 % of CH4 and CO2 conversions respectively at 700 °C. Ni_20 % is showing excellent resistance toward sintering after DRM stability test of 80 h. Characterizations made for spent catalyst show high resistance toward sintering and limited carbon formation. [ABSTRACT FROM AUTHOR]

The Review describes the most significant results achieved in France in the field of heterogeneous catalysis over the last 10 years and placed in the context of international research. The focus lies on the research conducted in French academic laboratories, often in close collaboration with industrial partners. A wide range of heterogeneous catalysis is covered, including ab initio calculations, biomass conversion, catalytic cracking, catalyst characterization, CO2 conversion, Fischer-Tropsch, pollution abatement, power-to-gas and kinetics. [ABSTRACT FROM AUTHOR]

The catalytic selective oxidation of iso butane to methacrolein (MAC) and methacrylic acid (MAA) is known to proceed via a Mars-Van Krevelen mechanism. When the reaction is performed in a common reactor with co-feeding of the reactant and oxygen, reactive oxygen species are present on the catalyst surface whereby non-selective oxidation reactions occur. In this work, we studied the possibility to decouple the redox mechanism meaning to separate the reactant oxidation step and the catalyst re-oxidation step for the selective oxidation of iso butane (IBAN) to MAC and MAA. For this purpose, two reactor configurations were employed: a periodic reactor and a two-zone fluidized bed reactor (TZFBR). Whereas the periodic reactor allows the temporal separation of the two steps, the TZFBR enables the spatial separation. A Cs-based Keggin type heteropolycompound was employed as catalyst and characterized before and after reaction by XRD, Raman and XPS to better understand the structural and chemical changes during the periodic operation. The effect of the oxygen/IBAN concentration on the performance was studied. For the periodic reactor it was found that the conversion of iso butane and the formation of products decreased with the consumption of available oxygen species in the catalyst during a period. For the whole periodic tests, low concentration of oxygen injected into the reoxidation part of the cycles led to a high selectivity to the desired products (MAC+MAA). [Display omitted] • A redox decoupling concept is applied to the selective oxidation of iso butane to methacrolein and methacrylic acid. • A periodic reactor and a Two Zone Fluidized Bed Reactor (TZFBR) are used. • The presence of adsorbed unselective oxygen species leads to CO x formation in the beginning of the reaction cycle. • The selective oxidation is based on lattice oxygen species. • Vanadium is constantly reduced and re-oxidized under reaction conditions (Mars-Van Krevelen mechanism). [ABSTRACT FROM AUTHOR]

The development of the future French and European bioeconomies will involve developing new green chemical processes in which catalytic transformations are key. The VAALBIO team (valorization of alkanes and biomass) of the UCCS laboratory (Unité de Catalyse et Chimie du Solide) are working on various catalytic processes, either developing new catalysts and/or designing the whole catalytic processes. Our research is focused on both the fundamental and applied aspects of the processes. Through this review paper, we demonstrate the main topics developed by our team focusing mostly on oxygen- and hydrogen-related processes as well as on green hydrogen production and hybrid catalysis. The social impacts of the bioeconomy are also discussed applying the concept of the institutional compass. [ABSTRACT FROM AUTHOR]

In this paper, we report for the first time a one-pot reaction enabling total transformation of lactic acid to acetic acid over a Mo-V-Nb mixed oxide catalyst having an optimal atomic ratio 19:5:1. The mechanism of the reaction consists in two parallel ways leading to acetic acid: (i) oxi-dehydrogenation of lactic acid to pyruvic acid followed by decarboxylation and (ii) decarbonylation of lactic acid to acetaldehyde followed by oxidation. In the operating conditions we used, the catalyst is very active (total conversion of lactic acid) and selective towards acetic acid (100% selectivity). A 100% yield into acetic acid is hence obtained. [ABSTRACT FROM AUTHOR]

Highlights: [•] 40wt.% loading of (NH4)3HPMo11VO40 on Cs3PMo12O40 leads to the better thermal stability. [•] Cross-transfer of V and Cs species was found to be responsible for the partial deactivation of the catalysts. [•] Selectivity in methacrylic acid and methacrolein increased with the amount of strong and very strong acidic sites. [•] Relationship between surface acid density and the catalytic activity was established. [ABSTRACT FROM AUTHOR]

As part of a research on the application of open science principles to the field of bioeconomy, we conducted a scientometric study of the scientific production of France in this field, for the period 2015 to 2019. The bioeconomy is an approach that aims to replace fossil resources such as coal or oil by more environmentally friendly resources called "biomass". The study identified 1,913 publications in the Scopus database. We analyzed this corpus under various aspects: types and sources of documents, with volumetry and impact; authors, organisations and institutions; sources of funding; degree of internationality and openness (open access). The discussion focuses on the terminology and sources of such a scientometric study, on the accessibility of publications and on the position of France in this field. The conclusion proposes some recommendations for conducting a similar study, particularly for information professionals. [ABSTRACT FROM AUTHOR]

Core–shell SiO2@Au@TiO2 materials have shown excellent catalytic performances in the base-free oxidation of furfural (FF) to furoic acid (FA). The enhanced catalytic behaviour with respect to that observed over supported SiO2@TiO2@Au catalysts suggests a key role of the TiO2 shell, which could prevent Au deactivation by irreversible FA adsorption, improve metal–oxide interaction and presumably, give rise to the formation of new active sites located at the perimeter of the Au–TiO2 interface. [ABSTRACT FROM AUTHOR]

Abstract: The oxidation of undesirable sulfur compounds present in a desulfurized light gas oil (LGO; sulfur content: 39ppm) was performed with tert-butyl hydroperoxide (t-BuOOH) as the oxidant in the presence of a 16wt.% MoO3/Al2O3 catalyst. The oxidation activity of the sulfur compounds in the light gas oil increased when the O/S molar ratio increased up to 15; the activity slightly decreased for higher ratios. This optimal ratio was significantly higher that the stoichiometric one (=2) due to parallel oxidation reactions of olefins, etc., in the LGO. Further, we compared the oxidation reactivity of dibenzothiophene (DBT), 4,6-dimethyldibenzothiophene (4,6-DMDBT), and trimethyldibenzothiophene (C3-DBT), which are refractory compounds present in the light gas oil. The reactivity decreased in the order DBT⋙4,6-DMDBT>C3-DBT, irrespective of the WHSV and the temperature. Subsequent mathematical treatment revealed that the oxidative reaction of each sulfur compound follows a first-order kinetics. We found an activation energy of 32±2kJmol-1, whatever the compound, suggesting that the oxidation mechanism was the same for these compounds. Then, according to the proposed global process, the previously oxidized molecules in the treated light gas oil were further removed by adsorption over a silica gel at ambient temperature. As a result, the total sulfur content could be decreased after oxidation/adsorption to less than 5ppm. Further, N-containing model compounds were also treated according to the same procedure and the denitrogenation performance decreased in the order indole>quinoline>acridine>carbazole. Subsequently, the same process allowed decreasing the N content in the LGO from an initial value of 13.5ppm to a value of 0.8ppm, which is a remarkable result. [Copyright &y& Elsevier]

The effect of the Cs addition on the H2S inhibition and subsequently on the DBT HDS activity over Ru-based catalysts was investigated. In good agreement with a previous study, the HDS activity over a Ru catalyst containing cesium was much higher than that over the same Ru catalyst without cesium. On the other hand, the HDS activity of the Ru&z.sbnd;Cs catalyst was more inhibited by H2S than that of the Ru catalyst at 260 °C. Thus, kinetic parameters were calculated using a Langmuir–Hinshelwood model to determine the mechanism of the H2S inhibition over Ru and Ru&z.sbnd;Cs catalysts. We found that the heats of adsorption of DBT and H2S on the Ru&z.sbnd;Cs catalyst were higher than on the Ru catalyst, indicating that the sulfur-containing species adsorb more strongly on the catalyst containing cesium. Subsequently, the role of cesium in the Ru&z.sbnd;Cs catalyst on the DBT HDS activity was investigated by using 35S-tracer experiments. The results suggested that while the Ru&z.sbnd;Cs catalyst was more inhibited by H2S, the Ru&z.sbnd;S bonds were more stable on this catalyst than on the Ru catalyst. This Ru&z.sbnd;S bond stabilization was responsible for the stabilization of the active phase, which allowed creation of a greater amount of sulfur atoms potentially labile. Thus, that explained the better HDS activity over the Ru&z.sbnd;Cs catalyst than over the Ru catalyst, despite a greater H2S inhibition on the former. [Copyright &y& Elsevier]

Selective oxidation of isobutane to methacrolein (MAC) and methacrylic acid (MAA) has received great interest both in the chemical industry and in academic research. The advantages of this reaction originate not only from the low cost of the starting material and reduced process complexity, but also from limiting the use of toxic reactants and the production of wastes. Successive studies and reports have shown that heteropolycompounds (HPCs) with Keggin structure (under the form of partially neutralized acids with increased stability) can selectively convert isobutane to MAA and MAC due to their strong and tunable acidity and redox properties. This review hence aims to discuss the Keggin-type HPCs that have been used in recent years to catalyze the oxidation of isobutane to MAA and MAC, and to review alternative metal oxides with proper redox properties for the same reaction. In addition, the influence of the main reaction conditions will be discussed. [ABSTRACT FROM AUTHOR]

The search for the optimal coupling of several types of catalysts has inspired the development of multi-catalytic hybrid materials (MCHMs) featuring chemical and biological catalysts co-immobilised on the same support. This complex interdisciplinary strategy, located at the crossroads of chemistry, biology, and materials science, calls for a wide range of skills and offers access to MCHMs with diverse catalytic properties and applications. In particular, numerous organic and inorganic supports, both rigid or flexible, have been used to develop remarkable hybrid catalysts that exhibit synergetic effects and achieve yields and enantiomeric excesses unattainable through the separate use of catalyst constituents even in one-pot/one step processes. As the spearhead of hybrid catalysis, MCHMs concentrate the very essence of this field, requiring seamless communication and collaboration between chemists, biologists, materials scientists, and modelling specialists. Future developments in this area are expected to revolutionise catalysis and make it an inter- or even transdisciplinary research area. [ABSTRACT FROM AUTHOR]

Hybrid catalysis, which combines chemo‐ and biocatalytic benefits, is an efficient way to address green chemistry principles. 5‐Hydroxymethylfurfural (HMF) is a versatile building block in numerous industrial applications. To date, few studies have described the production of its amine derivatives and their polymers. Finding a good methodology to directly transform HMF to 5‐aminomethyl‐2‐furancarboxylic acid (AMFC) therefore represents an important challenge. After selecting the best oxidation catalyst for HMF conversion to 5‐aldehyde‐2‐furancarboxylic acid and immobilizing a transaminase onto a solid carrier, we implemented the first one‐pot/two‐steps hybrid catalytic process to produce AMFC (77 % yield); this is the most efficient AMFC catalytic production method from HMF reported to date. This process also produced 2,5‐furandicarboxylic acid (21 % yield) as a major secondary product that can be applied to polymer syntheses such as polyethylene furanoate. Herein, we report a novel way to access new biosourced polymers based on HMF oxidized and aminated derivatives. [ABSTRACT FROM AUTHOR]

• Zinc-tantalum on mesoporous silica TUD-1 catalyst showed remarkable activity in the conversion of ethanol to butadiene. • Plackett-Burman design identified key synthesis parameters for high productivity. • TUD-1 synthesis parameters compromised between surface area and pore diameter. • Response Surface Methodology identified high performing catalyst composition. The synthesis method of a zinc-tantalum catalyst supported on three-dimensional mesoporous silica with high specific surface area was studied. Its activity in the conversion of ethanol to butadiene was optimized using the Design of Experiment approach. A Plackett-Burman screening design identified the important preparation parameters, notably the ratio of Zn to Ta. It was subsequently optimized using the Response Surface Methodology, affording a highly active catalyst. [ABSTRACT FROM AUTHOR]

Selective oxidation of furfural to furoic acid was performed with pure oxygen in aqueous phase under mild conditions and uncontrolled pH using hydrotalcite-supported gold nanoparticles as catalyst. Hydrotalcites with different Mg: Al ratios were tested as support. The effects of reaction time, temperature and furfural/catalyst ratio were evaluated. The catalyst Au/HT 4:1 showed the highest activity and selectivity to the desired product, achieving a complete conversion of furfural to furoic acid after 2 h at 110 °C. Further, stability tests were carried out in a continuous stirred-tank reactor and a progressive deactivation of the catalyst due to the leaching of Mg2+ cations from the support inducing changes in the pH of the reaction medium was observed. [ABSTRACT FROM AUTHOR]

A zinc and tantalum-containing mesoporous silica catalyst highly active and selective in the Lebedev process has been prepared using the one-pot TUD-1 methodology. Selectivity towards butadiene reached 60–70%, making Zn–Ta-TUD-1 one of the best performing catalysts in the literature. To rationalize these results and establish a structure–activity relationship, a series of similar catalysts was prepared and characterized. Nitrogen physisorption, XPS, ICP-AES, XRD, TEM, UV-vis spectroscopy, TGA NH3-TPD, H2-TPR and FT-IR techniques were used. The most active samples were found to possess a large specific surface area and highly dispersed metal oxide phase incorporated within the mesoporous silica matrix. In combination with catalytic testing, characterization also showed a direct correlation between the number of Lewis acid sites and butadiene yield, confirming the structure–activity relationship theory prevalent for the Lebedev process. Deactivation of Zn–Ta-TUD-1 was also studied using the same techniques to characterize the properties of spent catalysts. It was found that the accumulation of heavy carbonaceous species caused a reduction of specific surface area and pore size coinciding with the observed loss in activity. Nevertheless, the pores of TUD-1 were large enough to avoid total pore blockage and a high selectivity could be maintained for 72 hours. [ABSTRACT FROM AUTHOR]

The selective hydroconversion of 5‐hydroxymethylfurfural (HMF) to biofuels is currently highly sought‐for. While the literature has demonstrated that this reaction is possible on promoted Ni catalysts, we show here that a monometallic, non‐promoted Ni/SBA‐15 catalyst, prepared by incipient wetness impregnation, can convert HMF to 2,5‐dimethylfuran (DMF) and to 2,5‐dimethyltetrahydrofuran (DMTHF) at 180 °C, in a consecutive way. Through a control over reaction time, high yields to DMF (71 %, at conversion of 93 %) or DMTHF (97 %, at conversion of 100 %) can be achieved. Kinetic modelling suggests a preferential route to DMF via 5‐methylfurfural (MFFR) as intermediate, though the route via 2,5‐bis(hydroxylmethyl)furan (BHMF) is also present. The favored route in the experimental conditions involves the hydrogenolysis of the hydroxyl group of HMF as first step, followed by the hydrogenation of the aldehyde function, to methylfurfuryl alcohol (MFOL). It is suggested a higher reaction rate of hydrogenation or hydrogenolysis of the side group is linked to the presence of a methyl group in the molecule. No hydrogenation of the furan ring is detected on the intermediates. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • First demonstration of efficient glycerol oxidation by laser activation of Gold Nanoparticles. • Glycerol oxidation is induced by thermoplasmonic effect of photoexcited GNPs. • More than 90% of Glycerol are converted after 2 h without any external source of heat. • The laser activation is 2.5 times more efficient than thermal activation at 60 °C. • Hot electron transfer between GNPs and TiO 2 contributes to the enhancement. Abstract In this work, we highlight the feasibility of new efficient catalytic processes by laser excitation, exemplified in the reaction of oxidation of glycerol over catalysts based on supported gold nanoparticles. We show that this catalytic oxidation reaction can efficiently proceed via laser excitation of surface plasmon resonance of gold nanoparticles, inducing local thermal heating effect. While the reaction did not occur in the absence of any external heat source, with this original approach, 88% of glycerol was converted after 2 h, leading to the formation of glyceric acid and tartronic acid as main products. The photonic activation led to 2.5 times more efficient conversion than an equivalent thermal activation by conventional heating source. Investigations of the laser power and the nature of support catalyst revealed a significant contribution of electron transfer from plasmonic nanoparticles to TiO 2 in the oxidation reaction. [ABSTRACT FROM AUTHOR]

Abstract: The transformation of DL limonene (mixture of D- and L-form ~ 1:1) that came from the pyrolysis of scrap tires rubber was studied using four heteropolyacid catalysts (H3PW12O40, H3PMo12O40, H4SiW12O40 and H4PMo11VO40) supported on Q-10, SBA-15, MCM-41, and KIT-6. The catalyst activity was measured using a py/GC/FID under a nitrogen atmosphere. The active phase and support were characterized using various technical methods (XRD, Raman, TEM, N2 adsorption-desorption, NH3-TPD, and py-FTIR). The highest weak acidity and largest number of Lewis acid sites promoted the conversion of DL limonene. The isomerization reactions seemed to be more favored than disproportionation reactions. The p-cymene yield was favored, with a high weak acidity and high Lewis/Brønsted acid sites ratio. Moreover, the results show that the use of amorphous support with a higher pore size seems to promote the conversion of DL limonene and the production of p-cymene.Graphical Abstract: HPA-based catalysts with Si are more favorable for converting DL limonene to p-cymene than those with P. For the HPA-based catalysts with P, the highest acidity favors the highest conversion, especially the Lewis acid sites. In this study, the isomerization reactions seem to be more favored than disproportionation reactions. [ABSTRACT FROM AUTHOR]

The acrolein production from methanol and ethanol mixtures over iron-molybdate-based catalysts was studied. The reaction to acrolein can be described by two successive steps: the first consists on the oxidation of both alcohols into their corresponding aldehydes and the second step is the subsequent aldol condensation of the as-formed aldehydes. The iron-molybdate catalysts were modified by doping with La and Ce (1%mol) in order to improve the aldol condensation step of the process. Series of catalysts were thus synthesized with different Mo/Fe ratios (i.e., 1.5, 2.0 and 2.5) and calcined at three different temperatures (i.e, 350 °C, 400 °C and 450 °C). The best catalytic performance was observed for FeMoCe2.0 (400 °C) for which the acrolein yield reached 42% (T = 320 °C, MetOH/EtOH = 1, GHSV = 3900 h −1 ). Furthermore, all the samples were characterised by TGA-DSC, HT-XRD, XPS, BET, LEIS, XRF, CO 2 -TPD, Pyridine (FTIR) and NH 3 (calorimetry) adsorption. The increase in acrolein yield observed upon La and Ce doping was attributed to acid/base properties modification. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Material property and catalytic performance significantly depending on Mn/Ce molar ratio in Mn X Ce 1 O Y. • Metallic Ru nanoparticles resistant to aggregation and oxidation due to strong metal-support interaction. • Availability and mobility of active oxygen species enhanced by surface Mn4+ and Ce3+ species. • A very high productivity of 5.3 mol FDCA ·mol Ru −1·h−1 obtained at FDCA yield of 99.9%. • Excellent catalytic stability and recyclability obtained on the Ru/Mn 6 Ce 1 O Y catalyst. Abstract Mn-Ce mixed oxides-supported Ru nanoparticles (Ru/Mn X Ce 1 O Y) with enhanced oxygen mobility and strong metal-support interaction were prepared and applied to the aerobic oxidation of 5 -hydroxymethylfurfural (HMF) to 2,5 -furandicarboxylic acid (FDCA) without addition of any base additives. Oxygen and water were used as green oxidant and solvent, respectively. The catalysts were characterized in depth by XRD, H 2 -TPR, O 2 -TPD, UV–Vis DRS, XPS and TEM, to reveal materials properties from bulk to surface. The influence of Mn/Ce molar ratios in support materials and reaction parameters (i.e. , HMF/Ru ratio, O 2 pressure, reaction temperature and time) was systematically studied and optimized. The reaction route and rate-determining step for oxidation of HMF to FDCA over the Ru/Mn X Ce 1 O Y catalysts were investigated by kinetic analysis. Well-dispersed metallic Ru nanoparticles with a mean size of 4.4 nm deposited on the support were found essential to activate and oxidize the HMF molecule. The Mn/Ce molar ratio was found to affect not only conversion of HMF but also distribution of products. The Ru/Mn 6 Ce 1 O Y catalyst demonstrated an exceptional yield (≥99%) of FDCA, which corresponds in our conditions to one of the best productivity (5.3 mol FDCA ·mol Ru −1·h−1) ever reported in literature. The superior activity of the Ru/Mn 6 Ce 1 O Y catalyst was mainly associated with (i) the strong metal-support interaction and (ii) the synergistic effect between manganese and cerium oxides. This catalyst showed the highest surface concentrations in Mn4+ and Ce3+ among the series, which, as a consequence, enhanced the availability and mobility of active oxygen species. This catalyst was shown resistant to deactivation during eight recycling uses thanks to a strong metal-support interaction between Ru nanoparticles and the Mn-Ce mixed oxide used as a support. [ABSTRACT FROM AUTHOR]

Notably available from the cellulose contained in lignocellulosic biomass, glucose is a highly attractive substrate for eco-efficient processes towards high-value chemicals. A recent strategy for biomass valorization consists on combining biocatalysis and chemocatalysis to realise the so-called chemo-enzymatic or hybrid catalysis. Optimisation of the glucose conversion to 5-hydroxymethylfurfural (HMF) is the object of many research efforts. HMF can be produced by chemo-catalyzed fructose dehydration, while fructose can be selectively obtained from enzymatic glucose isomerization. Despite recent advances in HMF production, a fully integrated efficient process remains to be demonstrated. Our innovative approach consists on a continuous process involving enzymatic glucose isomerization, selective arylboronic-acid mediated fructose complexation/transportation, and chemical fructose dehydration to HMF. We designed a novel reactor based on two aqueous phases dynamically connected via an organic liquid membrane, which enabled substantial enhancement of glucose conversion (70%) while avoiding intermediate separation steps. Furthermore, in the as-combined steps, the use of an immobilized glucose isomerase and an acidic resin facilitates catalyst recycling. [ABSTRACT FROM AUTHOR]

Abstract: The deoxydehydration (DODH) of glycerol was studied using several Re‐based catalysts in the liquid phase under atmospheric pressure conditions. The best performance was observed over 10 wt.% ReOx/Al2O3 with 2‐hexanol as a reductive agent giving allyl alcohol with an exceptional yield of 91%. The reaction was confirmed to be catalysed heterogeneously, since the reaction stopped upon removal of the catalyst by hot filtration. The corresponding catalyst was further successfully reused three times without any leaching of rhenium species, as shown by elemental analysis. Based on the characterisation of the fresh and the spent catalyst by XPS and Raman spectroscopy, a reaction mechanism is proposed, which involves the redox‐couple Re(V) / Re(VII). [ABSTRACT FROM AUTHOR]

The liquid-phase oxidation of glycerol was studied to obtain glycolic acid as a value-added molecule. The effect of metal addition to silver based catalyst was investigated under strong basic condition. The best catalytic performance was obtained over silver catalyst promoted with a small amount of platinum Ag-Pt/CeO. Namely, the conversion close to 54% was reached after 5 h of reaction at 60 °C, with the selectivity to glycolic acid of 51%. Further increase in the amount of promotor (up to 50%) changed the reaction mechanism to product selectively the glyceric acid. Graphical Abstract: [ABSTRACT FROM AUTHOR]

The Front Cover shows the potential of catalysis in France.In their Review, H. Olivier‐Bourbigou et al. summarize the most significant breakthroughs reported in France over the last ten years in the field of heterogeneous catalysis. The Review focuses on the development of catalytic systems for specific applications, such as petrochemistry, biomass transformation, environmental applications and CO2 for energy. The significant cross‐disciplinary approaches, essential to understand and optimize catalytic processes, are also described. More information can be found in the Review by H. Olivier‐Bourbigou et al. on page 2029 in Issue 12, 2017 (DOI: 10.1002/cctc.201700426). [ABSTRACT FROM AUTHOR]

The catalytic acceptorless dehydrogenative oxidation of biosourced alcohols into carboxylic acid salts was achieved using earth-abundant Fe and Mn complexes that feature aliphatic PNP pincer ligands in good to excellent yields. The Fe derivatives were characterized by using 57Fe NMR spectroscopy. Mn pincer catalysts are catalytically more efficient than their Fe counterparts thanks to their robustness under basic conditions. Attempts to generate aldehydes from alcohols were not successful using the Fe and Mn species, but a commercially available Ru analogue achieves this transformation selectively under very mild conditions in the presence of a large excess of acetone as a hydrogen acceptor. [ABSTRACT FROM AUTHOR]

Through biomass valorization, sugars can become a major carbon resource for the production of fuels and chemicals by using catalysis. Hybrid catalysis, a direct combination of biocatalysis and chemocatalysis, may yield innovative solutions. 5-Hydroxymethylfurfural (5-HMF) is a platform molecule derived from glucose, for which fructose is a key intermediate. To overcome the thermodynamic enzymatic equilibrium between glucose and fructose, two methodologies based on hybrid catalysis are described herein. In the first method, the glucose isomerase and fructose-to-5-HMF dehydration chemocatalysts are simultaneously implemented in a multiphasic way to imply the complexation and transport of fructose. The second method proposes a route through sorbitol, obtained by the hydrogenation of glucose. Sorbitol is then enzymatically converted into fructose, whereas regeneration of the cofactor is performed in situ with an organometallic complex as a chemocatalyst. [ABSTRACT FROM AUTHOR]

The Guerbet reaction of ethanol to heavier products was performed over a series of extensively characterized Sr-substituted hydroxyapatites (HAPs) with different (Ca+Sr)/P ratios, and thus different structural, textural, and acid-base properties. The acid-base properties were correlated with the reactivity of the solids and an optimal ratio between the amount of acid and basic sites was determined (ca. 4), whereas the ethanol conversion was mainly depending on the specific surface area of the solids. The stoichiometric 100 mol % Sr-substituted sample (SrAp-100) was especially efficient in higher alcohols production, which can be illustrated by a total alcohol selectivity (76.4 %) higher than that of all the other solids at a 13 % ethanol isoconversion. [ABSTRACT FROM AUTHOR]

SBA-15 catalysts doped with variable aluminum amounts were prepared through a facile evaporation-induced self-assembly process. The textural properties and acidity of the catalysts could be tuned simply by varying the aluminum content. The genesis of acid sites with weak and medium strength during reaction was directly correlated to the catalytic activity for the dehydration of 1,3-butanediol into butadiene (BD). The best performance was achieved over an Al-SBA-15 sample with a silica/alumina ratio of 76, exhibiting a stable BD yield of 59 % at temperatures as low as 200 °C. [ABSTRACT FROM AUTHOR]

1,3-Butadiene is traditionally produced as a byproduct of ethylene production from steam crackers. What is unusual is that the alternative production route for this important commodity chemical via ethanol was developed a long time ago, before World War II. Currently, there is a renewed interest in the production of butadiene from biomass due to the general trend to replace oil in the chemical industry. This review describes the recent progress in the production of butadiene from ethanol (ETB) by one or two-step process through intermediate production of acetaldehyde with an emphasis on the new catalytic systems. The different catalysts for butadiene production are compared in terms of structure-catalytic performance relationship, highlighting the key issues and requirements for future developments. The main difficulty in this process is that basic, acid and redox properties have to be combined in one single catalyst for the reactions of condensation, dehydration and hydrogenation. Magnesium and zirconium-based catalysts in the form of oxides or recently proposed silicates and zeolites promoted by metals are prevailing for butadiene synthesis with the highest selectivity of 70% at high ethanol conversion. The major challenge for further application of the process is to increase the butadiene productivity and to enhance the catalyst lifetime by suppression of coke deposition with preservation of active sites. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

For a sustainable society, it is highly desirable to produce H 2 from renewable sources and with low energy consumption. Functional, cheap and easy-prepared Mg 2 AlNi X H Z O Y nano-oxyhydrides materials were successfully developed from Mg 2 AlNi X O Y nano-composites ex-hydrotalcites. After an in situ treatment in H 2 at low temperature (450 °C), the Mg 2 AlNi X O Y nano-composites (x > 1) become hydrogen reservoirs, called oxyhydrides, with the presence of hydrogen species of hydride nature that can be stored in the anionic vacancies of the solid. Advanced techniques in presence of H 2 including TPR, in situ XRD and INS were used to study the nano-composites with different Ni contents. The Mg 2 AlNi X H Z O Y nano-oxyhydrides (x > 1) are shown to be able to simultaneously provide hydride species and to totally convert ethanol and produce H 2 from a water-ethanol mixture in presence of O 2 , with very low energy input. In complement to the exothermic partial oxidation reaction, the chemical energy delivered from the strong exothermic reaction between hydride species and O 2 is used. The reaction is sustainable because hydride species are replaced and provided by ethanol. [ABSTRACT FROM AUTHOR]

A series of isolated or preformed in-situ aliphatic PNP-type pincer ruthenium complexes have been evaluated for deuterium labelling of alcohols' C-H functions with deuterium oxide. Under our catalytic conditions, pincer-supported ruthenium complexes bearing cyclohexyl substituents on the phosphorous atoms have been found to be the most efficient and regioselective catalysts for α-deuteration of primary alcohols, affording up to 94% of α -C-H deuteration with only 5% of β -C-H deuteration in the case of n -butanol. [ABSTRACT FROM AUTHOR]

Base-free catalytic acceptorless dehydrogenative homo-coupling of alcohols to esters under neat conditions was investigated using a combined organometallic synthesis and kinetic modelling approach. The considered bifunctional ruthenium aliphatic PNP complexes are very active, affording TONs up to 15,000. Notably, gas mass transfer issues were identified, which allowed us to rationalize previous observations. Indeed, the reaction kinetics are limited by the rate of transfer from the liquid phase to the gas phase of the hydrogen co-produced in the reaction. Mechanistically speaking, this relates to the interconverting couple amido monohydride/amino bishydride. Overcoming this by switching into the chemical regime leads to an initial turnover frequency increase from about 2000 up to 6100 h −1 . This has a significant impact when considering assessment of novel or reported catalytic systems in this type of reaction, as overlooking of these engineering aspects can be misleading. [ABSTRACT FROM AUTHOR]