Françoise Maugé

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 (Al ₂ O ₃ , 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 ≈ USY22 > Al ₂ O ₃ . 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.

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 TiO₂ to activate low-temperature (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 Pt²⁺ sites, followed by bond cleavage of Ti-O-Sn moieties nearby and the appearance of Pt⁴⁺ 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.

IR spectroscopy of CO adsorption (IR/CO) and Density Functional Theory (DFT) calculations on sulfide W/Al₂O₃ catalyst were investigated for an insight into the sulfide edge sites. Parallel between experimental and theoretical results allow to assign the ν(CO) bands at 2121 and 2066 cm⁻¹ to CO adsorption on M‐ and S‐edge sites of WS₂ phase, respectively. Through a careful analysis of CO spectra on well‐selected W catalysts, the molar attenuation coefficients for CO adsorbed on the two exposed edges could be determined. This allowed the morphology of WS₂ slabs to be calculated. This work shows that increasing the W loading (6–20 wt% W) changes the slab morphology from an almost pure triangle exhibiting mostly M‐edge to a truncated triangle. On W as well as on Mo sulfide catalysts, IR spectroscopy and DFT calculation show that CO adsorption allows to account for M‐ and S‐edge sites, and thus of the morphology of sulfide slabs. It was shown that increasing the W loading shifts the slab morphology from a triangle exposing predominantly M‐edge towards a more hexagonal shape. For close to monolayer coverage of alumina, Mo and W sulfide slabs present similar shape i. e. truncated triangle. However, edge sites of WS₂ slabs clearly exhibit greater stability under H₂ atmosphere than Mo sulfided ones.

Atomic-scale images of MoS ₂ slabs supported on γ -Al ₂ O ₃ were obtained by high-resolution scanning transmission electron microscopy equipped with a high angular annular dark field detector (HR STEM-HAADF). These observations, obtained for sulfide catalysts prepared with or without citric acid as a chelating agent, evidenced variations in morphology (shape) and size of the MoS ₂ nanoslabs, as detected indirectly by the adsorption of CO followed by infrared spectroscopy. Quantitative dispersion values and a morphology index (S-edge/M-edge ratio) were determined from the slabs observed. In this way, HR STEM-HAADF underlines that the addition of citric acid to Mo catalysts decreases the size of the particles and modifies the shape of the MoS ₂ nanoslabs from slightly truncated triangles to particles with a higher ratio of S-edge/M-edge. These finding are of great significance since tayloring the morphology of the slabs is a way to increase their catalytic activity and selectivity. Furthermore, this work demonstrated that the IR/CO method is a relevant approach to describe the MoS ₂ morphology of supported catalysts used in hydrotreatment processes for clean fuel production.

Hydrotreating catalysts were prepared from CoMgMoAl layered double hydroxides (LDHs) with different Co and Mo contents. Sulphides were characterised by techniques such as X-ray absorption near edge structure spectroscopy, CO adsorption followed by infrared spectroscopy, X-ray diffraction and nitrogen physisorption. The prepared catalysts were tested in the selective hydrotreating of a model feed (thiophene, cyclohexene and n-heptane) under 573 K and 20 bar of H₂, covering a wide range of space velocities (41–439 h⁻¹). All the LDH-derived CoMgMoAl sulphides showed larger selectivity for hydrodesulphurisation when compared to industrial catalysts. The characterisation results allowed a relationship between the nature and concentration of sulphide sites and their catalytic functionalities to be established.