The selective removal of oxygenates like phenol is a key challenge in upgrading biofuels. This study evaluates the adsorption performance and selectivity of zeolites (HY2.9, USY22, and USY40) and oxides (Al2O3, SBA-15) for phenol in the presence of fuel representative co-molecules (toluene, cyclohexane, and 2,3-dimethyl-2-butene) using batch experiments and, notably, operando ATR-IR spectroscopy. Batch adsorption capacities followed the order SBA-15 > HY2.9 > USY40 approximate to USY22 > Al2O3. Performance depends on a combination of factors such as specific surface area, pore size and pore density, as well as the density and nature of the acid sites. While cyclohexane had negligible impact, toluene and dimethylbutene induced competitive adsorption or site poisoning, with effects being nearly cumulative in complex mixtures. ATR-IR measurements not only corroborated batch trends but also provided molecular-level insights, demonstrating its relevance as a rapid, operando screening tool to assess adsorption mechanisms, selectivity, and regeneration potential with minimal material consumption. The findings highlight the advantage of weakly acidic or non-acidic adsorbents in complex mixtures and underscore the utility of ATR-IR for efficient adsorbent evaluation.

(Text in French)When the world community of catalysis meets in Lyon: the 18th International Congress on Catalysis. The 18th International Congress on Catalysis (ICC) was held in Lyon from July 14 to 19, 2024. Organized by several successive executive boards of the Catalysis Division of the French Society of Chemistry, the conference was a great success, gathering more than 2250 participants. It contributed to unifying the global catalysis community towards common goals. The rich and high-quality scientific program, along with a dynamic exhibition and friendly social events, made this event a particularly appreciated edition, and we hope, a memorable one. This report outlines the major steps in the organization that led to this success, to inspire future achievements of this magnitude. Initiatives implemented on this occasion, such as a call for short symposia, the establishment of a Committee of Young Researchers, an Ethics Committee, impacting both the scientific and extra-scientific program, are also highlighted.

Ti-incorporated SBA-15 catalysts were synthesized via a one-pot hydrothermal method and tested in the liquidphase oxidative desulfurization (ODS) process at 80 degrees C and atmospheric pressure for low-sulfur fuel production. These catalysts exhibited superior ODS performance compared to conventional impregnation-based catalysts. Characterization confirmed the successful incorporation of titanium ions into the SBA-15 framework, forming Si-O-Ti bonds with tetrahedrally coordinated Ti4+ species. Two types of Ti4+ sites-crystalline and isolated-were identified, with the isolated sites contributing more significantly to catalytic activity. The high accessibility of dibenzothiophene (DBT) to isolated Ti4+ sites, along with the minimal presence of crystalline TiO2 phases, were key factors in the enhanced performance. Quantitative analysis showed that isolated Ti4+ sites exhibited a turnover frequency (TOF) approximately 20 times higher than that of crystalline Ti4+ sites, confirming their role as the primary active sites in the ODS reaction.

With the motto "Roots and Wings for a Better World", the 18th International Congress on Catalysis, held in Lyon, France, from July 14th to 19th, 2024, has been an invaluable forum for the catalysis community to share its most advanced results. The dense and high-quality scientific program along with a vibrant exhibition and friendly social events have made this edition highly memorable.

The adsorption, catalytic and photocatalytic properties of titania strongly depend on its phase composition, morphology and the presence of impurities. In this work, we report new data on the surface acidity and catalytic performance of anatase–brookite TiO2 and compare them with data for a commercial anatase–rutile system (TiO2 Degussa P25). Pure titania was synthesized by the sol-gel method using titanium (IV) isopropoxide as a precursor. It consisted of anatase–brookite nanoparticles, as revealed by XRD, Raman spectroscopy and SEM. The sample has a monomodal, mesoporous structure with well-defined pore size around 7.5 nm. FTIR spectroscopy highlighted the impact of the bulk composition on the surface by identifying different hydroxyl groups associated with anatase and brookite TiO2. For both titania samples, the adsorption of 2,6-dimethylpyridine showed the existence of Lewis acid sites and two types of Brønsted acid sites of different strengths, but the density of all types of acid sites was much higher for the synthesized TiO2 polymorph. Anatase–brookite TiO2 is more active and selective in the dehydration of isopropanol to propene than TiO2 Degussa P25, which is associated with the significantly higher surface acidity of this catalyst.

Furfural, an important platform molecule obtained exclusively from the cyclodehydration of xylose, has numerous applications across a wide spectrum of sectors. However, the industrial production process is currently limited by the degradation of xylose and furfural to humins in the aqueous medium. While the in situ extraction of the furfural produced by an organic solvent proves to be beneficial, the remaining xylose, which is left in the aqueous phase, degrades at moderate to high-temperature conditions. To address this, we developed a novel cosolvent system (70:30 v/v% gamma-valerolactone: butanol) that achieves 100% xylose conversion and an 84% furfural yield, outperforming traditional water-based and mono-solvent systems in both selectivity and stability. This system leverages synergistic solvent interactions to stabilize reactive intermediates and reduce side reactions. Additionally, the HUSY-30 zeolite catalyst demonstrated excellent thermal stability and reusability over five cycles, outperforming conventional resins such as Amberlyst-15. A suite of ten pseudo-first-order kinetic models was developed, with the best-fit model confirming furfural formation via both direct and intermediate pathways and negligible humin formation, reinforcing the effectiveness of the co-solvent system. Beyond reaction optimization, we designed and validated a novel separation process based on liquid-liquid extraction, replacing conventional distillation. Simulation results showed reductions of 66.96% and 57.99% in cooling and heating duties, respectively. Overall, this integrated approach represents a significant advancement in sustainable furfural production by combining optimized catalysis, solvent engineering, kinetic modeling, and process intensification.

Molybdenum sulfide catalysts are considered of interest in the aim to find alternative to the Pt/C reference catalyst for electrocatalyzed Hydrogen Evolution Reaction (HER). Known since decades as hydrotreatment catalysts, their characterization has been widely detailed in order to draw structure-activity relationship and to optimize their design and preparation. In this study, we aim to draw a parallel between the catalytic activity in a model hydrodesulfuration (HDS) reaction and the one in electrocatalysis for HER reaction in order to verify that the optimization of the edge sites properties for HDS could also be beneficial for HER reaction.

The chalcogenide MoS2 has three polymorphs: 2 H; 3 R; 1 T. Each of them is endowed with interesting properties and characteristics which make them promising materials for photo- and electrocatalysis, photodevices and electronics. In this work, we demonstrate the impact of the chosen synthesis path in which molybdenum precursor is introduced on the formation of MoS2 on TiO2 nanotubes (TiNT) using FTIR spectroscopy. Thus,for the first time 1 T-MoS2 was obtained under H2S/H2 flow by incorporating Mo into the nanotube wall which might be an interesting approach for industrial scaling-up procedures. Moreover, unprecedently we report the possible detection of 1 T-MoS2 via IR-transmission using CO as a probe molecule.

To address environmental pollution, the chemical industry is continually refining its standards. In the United States and Europe, regulations stipulate that the sulfur content in diesel fuel must not exceed 15 ppm. This stringent requirement has driven continuous research into advanced fuel upgrading techniques. One such promising method is oxidative desulfurization (ODS), which removes sulfur compounds by converting them into sulfones, thereby improving their extractability into other phases. This mini-review aims to provide a qualitative analysis of the fundamental principles of ODS. It examines the roles of various oxidizing agents, extraction solvents, and heterogeneous catalysts, highlighting their respective advantages and limitations. Furthermore, the review elucidates the integrated reaction-extraction approach and explores emerging technologies and challenges associated with biodiesel upgrading in the context of biofuels. A quantitative section synthesizes representative results to provide a comprehensive overview. In conclusion, this paper underscores the importance of understanding both the benefits and limitations of ODS and emphasizes the necessity for ongoing research in the field of biodiesel production.

Developing alternatives to platinum (Pt) and iridium (Ir) in proton-exchange membrane water electrolyzers is crucial on the way to viable energy provision schemes. However, although it seems difficult to substitute Ir, alternatives exist for Pt at the proton-exchange membrane water electrolyzer cathode. Here, we report on the synthesis and the characterization of efficient and durable hydrogen evolution reaction (HER) nanocatalysts based on MoS2 supported on high-surface-area carbon. Citric acid was used as a chelating agent to control the size of the MoS2 crystallites (1.4 nm) and thus the density of active sites (slab edges). Inspired by successful approaches in catalysis for hydrodesulfurization reactions, conventional 2H MoS2 was sequentially doped with cobalt (Co) and then with 1 wt % of Pt. Overpotentials of 188, 140, and 118 mV at 10 mA cm-2 are reported for MoS2/C, Co- MoS2/C, and Pt1%-CoMoS2/C, respectively. This result is attributed to the weakening of the Hads binding energy of the promoted MoS2-edge active sites (because the promoting atoms are mostly located at the edges). Associated with small-metal dissolution rates (monitored in situ, during the HER), our findings demonstrate that metal promotion (doping) is a promising route to replace Pt with earth-abundant elements in acidic water electrolyzers.

The spillover of oxygen species is fundamentally important in redox reactions, but the spillover mechanism has been less understood compared to that of hydrogen spillover. Herein Sn is doped into TiO 2 to activate low-temperature (<100 °C) reverse oxygen spillover in Pt/TiO 2 catalyst, leading to CO oxidation activity much higher than that of most oxide-supported Pt catalysts. A combination of near-ambient-pressure X-ray photoelectron spectroscopy, in situ Raman/Infrared spectroscopies, and ab initio molecular dynamics simulations reveal that the reverse oxygen spillover is triggered by CO adsorption at Pt 2+ sites, followed by bond cleavage of Ti-O-Sn moieties nearby and the appearance of Pt 4+ species. The O in the catalytically indispensable Pt-O species is energetically more favourable to be originated from Ti-O-Sn. This work clearly depicts the interfacial chemistry of reverse oxygen spillover that is triggered by CO adsorption, and the understanding is helpful for the design of platinum/titania catalysts suitable for reactions of various reactants.

In previous reports, it was proposed that the oxygen-substituted Mo(SxOy)zc site formed in situ by water is active center for water-gas shift reaction catalyzed by MoS2. However, water is also hypothesized to be the driving force for sulfide catalyst deactivation. This irreconcilable dispute stems from the limited understanding about the reaction mechanism and the lack of relevant in situ or/and operando characterization. In this work, the different reactivity of the two preferentially exposed MoS2 edge sites, M-edge and S-edge sites, with CO and H2O is revealed by means of in situ CO adsorption followed by IR spectroscopy. Isotopic reactants (13CO/12CO; H218O) were used to account for the origin of the formed products and catalyst surface modification. In particular, upon H2O feed, S/O exchange occurs on M-edge leading to Mo(SxOy)zc sites that are not reactive towards subsequent CO feed in contradiction with a redox mechanism in which the catalyst surface is first exchanged by H2O and then reduced by CO. Moreover, the M-edge sites hardly give vacancy under CO treatment. Conversely, the S-edge sites are much less prone to S/O exchange upon H2O feed but are sensitive to CO to form vacancies and release COS. In addition, IR operando studies are in accordance with a formate pathway and a novel redox mechanism via COS formation. This insight into the catalytic active sites under reaction conditions allows to identify the M-edge sites as the ones leading to the deactivation of the catalyst and the S-edge sites as the redox active sites. Thus, the work gives the direction for the rational design of high-performance and stable sulfide catalysts for reactions involving H2O dissociation and CO conversion.

MoS 2 is a promising sulfur‐resistant candidate for water‐gas shift (WGS) reaction, and its catalytic efficiency can be promoted by alkali metal. In this work, a series of K‐modified MoS 2 /Al 2 O 3 catalysts with variable K/Mo ratios were prepared to elucidate the promotion role of potassium through IR spectroscopy studies. CO adsorption followed by IR spectroscopy shows that after potassium addition the number of accessible edge sites of MoS 2 slabs is decreased. Meanwhile, the downward shift of v (CO/MoS 2 ) indicates that the presence of potassium increases the electronic density of Mo atoms. This electronic effect activates terminal S atoms, favoring their reaction with CO to form COS at lower temperature than in absence of K. Additionally, conversely to the case of MoS 2 /Al 2 O 3 catalysts, little or even no formate species are observed on K‐modified MoS 2 catalysts during IR operando studies, implying a change of the WGS reaction route that would explain the beneficial effect of K on MoS 2 edge site activity.

MS 2 morphology is strongly influenced by several parameters including the addition of a chelating agent and sulfidation temperature. In this work, we report the use of citric acid as chelating agent in order to prepare a series of WS 2 /Al 2 O 3 catalysts that were submitted to sulfidation at several temperatures. The effect of these two parameters in the morphology of the slabs was explored by means of CO adsorption at low temperature followed by IR spectroscopy (IR/CO) and later confirmed by High-Resolution Scanning Transmission Electron Microscopy coupled with High Angular Annular Dark Field detector (HR STEM - HAADF). This allowed to depict the morphology of WS 2 slabs by means of calculating the M-edge/S-edge site ratio. The use of citric acid in the preparation stage favors the increase of S-edge site concentration whereas it keeps that of M-edge sites: according to IR/CO, with an increasing amount of citric acid, the WS 2 morphology progressively changes from a slightly truncated triangle exhibiting predominantly M edges to a hexagon with both M edge and S edge. In addition, HR STEM-HAADF demonstrated that the addition of citric acid in the impregnation step of W catalysts considerably reduces the size of WS 2 nanoparticles increasing their dispersion degree. The morphology of the WS 2 plates on the activated WS 2 /Al 2 O 3 catalyst with a typical sulfidation temperature range (573–673 K) was detected to be a truncated triangle exposing both the M-edge and the S-edge. Furthermore, the IR/CO results indicate that the degree of truncation (ratio of S-edge/M-edge) of WS 2 slabs gradually rises with the increasing sulfidation temperature. However, the most determining factor for a modification of the morphology of the slabs turns out to be the presence of citric acid as a chelating agent and not the sulfidation temperature. This change in morphology (i.e., change of S-edge/M-edge ratio) is a key factor for catalytic performance, since the M-edge and the S-edge show different reactivity in hydrodesulfurization (HDS) reactions. Notably, it was also found that the addition of citric acid not only improves the catalytic activity but also the stability of the catalysts, giving the best performance in concentrations higher than (CA/W = 1).

In this paper NiW/gamma-Al2O3catalysts were prepared by consecutive impregnation of a W/gamma-Al2O3 catalyst with an aqueous solution of nickel salt. The structural control of the nickel ion precursor in the impregnation solution was achieved by the addition of 1, 2-cyclohexanediamine-N, N, N', N'-tetraacetic acid (CyDTA) as a chelating agent at different pH. The influence of the sulfidation pressure (1 bar vs 40 bar) on the activity and structure of the NiW catalysts was investigated. The catalysts performances were tested in hydrodesulfurization (HDS) of thiophene after sulfidation at atmospheric or high pressure. The catalysts were characterized by X-Ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR) and infrared spectroscopy of adsorbed CO (IR/CO) to explain the modification in surface species composition due to the chelating agent CyDTA and sulfiding conditions. NiW catalysts prepared in presence of CydTA and sulfided under high pressure displayed the highest HDS activity. These two factors enhanced the sulfidation degree of W-based species as characterized by XPS. A linear correlation was found between the HDS activity and the sulfidation degree. In addition, chelating agent addition induced a decrease on metal-support interaction, as pointed out by TPR, and strongly favored the creation of CUS sites on the NiWS phase as seen by IR/CO. All these features favored a high catalytic activity. In addition, high pressure sulfidation not only leads to more active NiW catalysts but improved the butene-over-butane ratio.

In this work, we present atomic-scale images of Co promoted MoS2 slabs supported on gamma-Al2O3 obtained by High Resolution Scanning Transmission Electron Microscopy equipped with High Angular Annular Dark Field detector (HR STEM-HAADF). These images allow to study the effect of citric acid (CA) addition during preparation, on the slab length and its stability during thiophene hydrodesulfurization (HDS) reaction. Thus, the observations, obtained for sulfide catalysts prepared without or with citric acid as chelating agent, evidenced strong decrease in size of the CoMoS nano-slabs as detected indirectly by the adsorption of CO followed by Infrared spectroscopy (IR/CO). Quantitative dispersion values were calculated from the images taking into account the true shape of the particles instead of the classical hexagonal shape hypothesis. Characterization of the used catalyst shows that these nanoclusters are stable under model thiophene HDS reaction. Such observations allow a better understanding of the effect of chelating agent addition on promoted MoS2 samples in order to explain their catalytic activity.

Ever more active hydrotreating (HDT) catalysts should be developed to meet the growing demand for cleaner fuels. With each novel generation of HDT catalysts the requirements of performance, stability and possibility of regeneration become more sophisticated. Versatile types of organic molecules are applied to improve the HDT catalysts, and to activate regenerated catalysts. The additives improve the dispersion of the active phase, the degree of promotion and modify the interactions with the support. Complex chemical and physical processes are involved in the mechanisms of action, which are different from one family of additives to another. In this review we summarize recent advances on the main types of additives, the current state of understanding of the mechanisms of their action as well as challenges and perspectives in developing novel additives for highly performing novel generations of HDT catalysts in a sustainable way.