Antonio Aguilar-Tapia

In Cu–Zn catalysts used for the reverse water–gas shift (RWGS) reaction, Cu and Zn phases remain dispersed, while the Cu–Zn interphase is widely regarded as the catalytically active site. Herein, we engineered a ZnO‐decorated Cu‐rich Cu–Zn alloy using a mixed Cu/Zn oxalate‐based supramolecular metal–organic framework precursor with compositionally homogeneous Cu/Zn mixing. The resulting Cu–Zn catalyst (Cu–Zn|C‐oxo|R) maintained >99% CO selectivity and, at 550°C, delivered a Cu‐normalized CO space–time yield (STY) of 1580 mmol _CO g _Cu ⁻¹ h ⁻¹ , higher than those of the Cu‐only and commercial Cu–Zn–Al benchmarks. Under a high space velocity test, the Cu–Zn|C‐oxo|R catalyst remained stable for >50 h at 550°C. Operando Cu K‐edge x‐ray absorption spectroscopy shows that Cu is reduced to a predominantly metallic local environment that persists under RWGS conditions. Complementary in situ x‐ray diffraction and electron microscopy identify Cu‐rich Cu–Zn alloy domains in contact with ZnO, while in situ diffuse reflectance infrared Fourier transform spectroscopy is consistent with an associative formate‐mediated RWGS pathway at these interfaces. Density functional theory calculations further revealed that these interfacial sites favor the formate reaction pathway, providing a molecular‐level rationale for the enhanced catalytic activity.

In Cu–Zn catalysts used for the reverse water–gas shift (RWGS) reaction, Cu and Zn phases remain dispersed, while the Cu–Zn interphase is widely regarded as the catalytically active site. Herein, we engineered a ZnO‐decorated Cu‐rich Cu–Zn alloy using a mixed Cu/Zn oxalate‐based supramolecular metal–organic framework precursor with compositionally homogeneous Cu/Zn mixing. The resulting Cu–Zn catalyst (Cu–Zn|C‐oxo|R) maintained >99% CO selectivity and, at 550°C, delivered a Cu‐normalized CO space–time yield (STY) of 1580 mmol _CO g _Cu ⁻¹ h ⁻¹ , higher than those of the Cu‐only and commercial Cu–Zn–Al benchmarks. Under a high space velocity test, the Cu–Zn|C‐oxo|R catalyst remained stable for >50 h at 550°C. Operando Cu K‐edge x‐ray absorption spectroscopy shows that Cu is reduced to a predominantly metallic local environment that persists under RWGS conditions. Complementary in situ x‐ray diffraction and electron microscopy identify Cu‐rich Cu–Zn alloy domains in contact with ZnO, while in situ diffuse reflectance infrared Fourier transform spectroscopy is consistent with an associative formate‐mediated RWGS pathway at these interfaces. Density functional theory calculations further revealed that these interfacial sites favor the formate reaction pathway, providing a molecular‐level rationale for the enhanced catalytic activity.

Operando X‐ray absorption spectroscopy (XAS) has undergone a transformation thanks to advances in synchrotron instrumentation and reactor‐cell design, enabling studies of heterogeneous catalysts under working conditions. This topical review surveys these developments and shows how they are implemented on the BM30 (FAME‐PIX) and BM16 (FAME‐UHD) beamlines at the European Synchrotron Radiation Facility (ESRF). Both beamlines now combine high‐flux optics with catalysis‐oriented detection, including a 16‐element Mirion HPGe solid‐state detector (SSD) for sensitive XAS of active sites and a 14‐crystal analyzer spectrometer for high‐energy‐resolution fluorescence detection (HERFD) and X‐ray emission spectroscopy (XES) to track changes in oxidation state and local structure. They also include operando reactor cells capable of operating at temperatures up to 1000°C and pressures up to 100 bar, matching industrial catalytic conditions. We describe the beamline configurations, sample environments and detection modalities, and discuss how their combined use enables real‐time structural and electronic characterization of catalysts. Case studies on methane reforming, ethane dehydrogenation, CO ₂ hydrogenation and methane dehydroaromatization demonstrate the scientific impact and versatility of these setups. Collectively, BM30 and BM16 are key tools for operando XAS and help bridge the gap between fundamental understanding and industrial catalytic processes.

The direct conversion of dimethyl ether (DME) to liquid fuels offers an attractive single-step route to high-octane gasoline. However, achieving the required synergy between metal and acid functions remains a long-standing challenge: Ni promotes hydrogenation but also triggers unselective hydrogenolysis, while zeolite acid sites initiate C-C coupling yet suffer from rapid deactivation. Here we report an induction-programming strategy that dynamically transforms NiO_x/ZSM-5 into a cooperative Ni/NiₓC/zeolite interface under reaction conditions. This interface suppresses methane and aromatics formation, while directing the reaction pathway toward branched isoparaffins with high yield and stability. Operando X-ray absorption spectroscopy and in situ spectroscopies reveal the progressive reduction of NiO to metallic Ni and its controlled carburization into Ni_xC, correlating phase evolution with the onset of selective tandem catalysis. Through control of the active phase's temporal evolution, induction programming offers a versatile framework for activating bifunctional catalysts and achieving spatiotemporal control of complex reactions beyond DME conversion.

Cathodes functionalised using molecular catalysts represent a promising approach for the efficient conversion of CO₂ into valuable products, with the potential to meet the performance metrics relevant to industrial applications. However, assessing the intrinsic activity of the metal centre while maintaining stability of the catalysts molecular scaffold during electrolysis still remains a challenge. This work focuses on the in-depth characterisation of a tetraaza-macrocyclic cobalt complex-based molecular cathode, from gaining a more accurate description of the catalysts performance metrics to the investigation of its probable deactivation pathway during electrocatalytic CO2 reduction (CO2RR). Importantly, our findings confirm that lowering the surface concentration of the catalysts allows to reach a catalytic regime where the activity is not anymore limited by mass transport within the porous multiwalled carbon nanotubes film but by the intrinsic activity of the immobilised catalyst, therefore allowing to determine its TOFmax value of 4.9 s-1. We propose that at least two populations of catalysts are present at the electrode surface, with variable contribution to the electrocatalytic process. Post operando studies provide key insights on the deactivation process of the immobilised catalyst via hydrogenation of both imine functions followed by demetallation.

Rare earth elements (REEs) behavior in acid mine drainage (AMD) during neutralization in estuaries is controlled by adsorption onto schwertmannite and basaluminite surface.

This paper presents the development of a novel high-pressure/high-temperature reactor cell dedicated to the characterization of catalysts using synchrotron x-ray absorption spectroscopy under operando conditions. The design of the vitreous carbon reactor allows its use as a plug-flow reactor, monitoring catalyst samples in a powder form with a continuous gas flow at high-temperature (up to 1000 °C) and under high pressure (up to 1000 bar) conditions, depending on the gas environment. The high-pressure/high-temperature reactor cell incorporates an automated gas distribution system and offers the capability to operate in both transmission and fluorescence detection modes. The operando x-ray absorption spectroscopy results obtained on a bimetallic InCo catalyst during CO2 hydrogenation reaction at 300 °C and 50 bar are presented, replicating the conditions of a conventional microreactor. The complete setup is available for users and permanently installed on the Collaborating Research Groups French Absorption spectroscopy beamline in Material and Environmental (CRG-FAME) sciences and French Absorption spectroscopy beamline in Material and Environmental sciences at ultra-high dilution (FAME-UHD) beamlines (BM30 and BM16) at the European Synchrotron Radiation Facility in Grenoble, France.

The impact of a fatty triamine (Triameen YT) additive was investigated on the friction performance and stability of molybdenum dithiocarbamate (MoDTC) in the formulations containing polyalphaolefin synthetic base oil (PAO) and zinc dialkyldithiophosphate (ZDDP). Triamine has no significant effect when mixed with MoDTC and ZDDP, but it improves the performance of MoDTC alone. However, in the MoDTC—Triamine—PAO solutions, a chemical reaction easily occurred and a reddish precipitate was formed upon storage. According to IR, XPS, TEM, and XAS characterizations, this precipitate is poorly crystalline layered alkylammonium oxothiomolybdate. Formation of the precipitate impaired the tribological performance by decreasing the number of active species delivered at the sliding contact interface. However, low friction coefficients were recovered by redispersion of the precipitate in PAO.

Mn-based oxides are promising for the selective catalytic reduction (SCR) of NOx with NH₃ at temperatures below 200 °C. There is a general agreement that combining Mn with another metal oxide, such as CeOx improves catalytic activity. However, to date, there is an unsettling debate on the effect of Ce. To solve this, here we have systematically investigated a large number of catalysts. Our results show that, at low-temperature, the intrinsic SCR activity of the Mn active sites is not positively affected by Ce species in intimate contact. To confirm our findings, activities reported in literature were surface-area normalized and the analysis do not support an increase in activity by Ce addition. Therefore, we can unequivocally conclude that the beneficial effect of Ce is textural. Besides, addition of Ce suppresses second-step oxidation reactions and thus N₂O formation by structurally diluting MnOx. Therefore, Ce is still an interesting catalyst additive.