Josefine Schnee

• Bioengineer in Chemistry - PhD in Catalysis
• CNRS Researcher at French National Centre for Scientific Research - Sorbonne Université

Hydroxyapatite (HAp)‐supported cobalt catalysts have been evaluated in the oxidative dehydrogenation of propane to propene (ODHP). The morphology of the HAp supports and the cobalt immobilisation mechanisms strongly influence the surface accessibility of cobalt species and their dispersion. A calibration curve obtained from NO‐TPD experiments for t...

Bio-oils obtained from rapid pyrolysis have emerged as a renewable energy source, but their high content of oxygenated molecules gives them unwanted properties for their use as fuels. Hydrodeoxygenation (HDO) is the process used to improve its quality and is commonly studied with model molecules such as guaiacol. Bimetallic NiCu catalysts are highl...

The 1st Thematic School ‘‘Vibrational and electronic spectroscopies applied to the study of reaction mechanisms – MECAREACT’’ (https://mecareact.sciencesconf.org/) was held in Paris, France, from June 18 to June 23, 2023. The School was organized by the Laboratory of Surface Reactivity (LRS), Sorbonne University, France, and by the French National...

Ultrasound-assisted co-precipitation method was used to synthesize Ni-LDH based catalysts for CO2 methanation. The influence of ultrasonic irradiation power density (90, 180, 270, and 360 W·L-1) on the physico-chemical properties of the catalysts as well as on their catalytic behavior was studied as compared to catalysts prepared by conventional co...

Being a promising renewable fuel, the production of dimethylether (DME) via the gas phase condensation of methanol nowadays attracts growing interest. Because of their exceptionally high Brönsted super-acidity, heteropolyacids (HPAs) deserve to be explored in this context. The Keggin H3PW12O40 HPA indeed allows reaching high methanol conversions at...

Time-resolved infrared (IR) spectroscopy is a widely used technique in the investigation of photoinduced reactions, given its capabilities of providing structural information about the presence of intermediates and the reaction mechanism. Despite the fact that it is used in several fields since the '80s, the communication between the different scie...

Catalytic activity of TiO2, 2%Re-TiO2 and 10%Re-TiO2 in the conversion of carbohydrates into levulinic acid under autoclave conditions was evaluated. These materials were prepared by aerogel method and characterized by...

TiO2 pillared clay was prepared by intercalation of titan polyoxocation into interlamelar space of an Algerian montmorillonite and used for the photocatalytic degradation of the linuron herbicide as a target pollutant in aqueous solution. The TiO2 pillared montmorillonite (Mont-TiO2) was characterized by X-ray photoelectron spectroscopy (XPS), X-Ra...

The promotion of a Pd catalyst with Au leads to higher and stable activity for the direct decomposition of NO, due to improved oxygen desorption.

Keggin heteropolyacids (HPAs) have been known to be efficient NOx absorbers for many years, and to be able to decompose a significant fraction of NOx species preabsorbed at 100−150 °C into harmless N2 and O2 upon rapid heating to 450 °C. However, this capability of Keggin HPAs to directly decompose NOx in the absence of a reducing agent in the feed...

In 1-butanol dehydration (gas phase) on a Keggin heteropolyacid (HPA) catalyst, the large size of 1-butanol and its significant hydrophobicity make the bulk-type (also called pseudo liquid-type) catalytic mechanism impossible. This drastically limits the catalytic effect on the surface of the HPA, with an activity lower than what it could be. To ov...

In the present work, a new quantum cascade laser (QCL)-assisted operando FT-IR setup was used to get direct insight into the relationship between the overall catalytic performance of TiO2 photocatalysts in the gas phase photooxidation of methanol at 25 °C, and the kinetics of intermediate surface formate species. Apparent rates of formation (Rapp,f...

A series of titania pillared Algerian montmorillonite was prepared from Na-montmorillonite using titanium isopropoxide and hydrochloric acid. Next to a reference clay pillared with TiO2 only(Mont-TiO2), a clay pillared with the palladium doped TiO2 was also synthesized(Mont-(TiO2-Pd)) as well as a TiO2-pillared clay photosensitized by the introduct...

How do you like your acid catalyst? A robust and modular method is presented for the preparation of silica‐supported sulfonic acid catalysts. The strategy makes it possible to fine tune both their acid strength and surface polarity, taking advantage of the copper‐catalyzed azide‐alkyne cycloaddition (CuAAC) and further modification of the formed tr...

Solid acid catalysts are central in our chemical industry and are major players in the valorization of bioresources. However, there is still a need to develop solid acid catalysts with enhanced acid strength and improved, or tunable, physicochemical profile to enhance the efficiency and sustainability of chemical processes. Here, a modular approach...

Pyridine is since a long time used as an infrared (IR) molecular probe to characterize the acidity of solids, in particular of heteropolyacids (HPAs). The latter are metal-oxygen-clusters nowadays widely used in acid catalysis. Indeed, thanks to their exceptionally strong Brönsted acidity, they allow operating chemical reactions under significantly...

Dimethylether (DME) is nowadays considered as one of the most promising alternative fuels for the future. It has a very low climate impact, and can be produced in a renewable way, namely from the gas phase condensation of methanol over common acid catalysts such as γ-Al2O3 or zeolites. The challenge today is to switch from high reaction temperature...

For the first time, a standard rapid-scan Fourier-transform infrared (FT-IR) spectrometer was coupled with quantum cascade lasers (QCLs) tunable within the 1876 – 905 cm-1 spectral range, within one single setup, by keeping one single sample compartment. The aim was to extend the time resolution of absorption measurements by several orders of magni...

A hydrolytically stable titanium carboxylate-based MOF, incorporating hydrogen-sulfate functions bounded to Ti-metal sites and named MIP-177-SO4H-LT, was prepared using a green and simple synthesis protocol. This solid exhibits a very high proton conductivity of 2.6×10-2 S cm-1 at 298 K and 95% Relative Humidity as evidenced by impedance spectrosco...

The gas-phase glycerol (Gly) transformation in the presence of oxygen has been studied on cobalt oxide systems (10 and 20 wt% Co) supported on a synthetic mesoporous aluminium phosphate (AlPO4) calcined at 350 °C, as well as on a binary Co-Al phosphate with a Co content of 10 wt%. Synthetic binary phosphate of Al-M (M=Fe, V) have also been tested....

Herein, we present the preparation by the non-hydrolytic sol-gel (NHSG) route of a mesoporous SiO2-TiO2 epoxidation catalyst with high specific surface area and large pores, and we discuss its modification by me- thylation. The pristine NHSG catalyst is tested for the catalytic conversion of cyclohexene with H2O2 in acet- onitrile, showing performa...

Keggin heteropolyacids (HPAs) are metal-oxygen clusters being nowadays considered as highly promising catalysts for the gas phase conversion of methanol to dimethylether (DME), namely the so-called “fuel for the 21st Century”. Indeed, thanks to their unusually strong Brönsted acidity approaching the super-acid region, Keggin HPAs allow reaching hig...

The gas phase dehydration of methanol to dimethylether (DME) nowadays attracts more and more interest as DME is one of the most promising renewable fuels for the future. As catalysts, many studies now use heteropolyacids (HPAs) which have an exceptionally high Brönsted acidity. In the present work, H3PW12O40 (most widely used Keggin-type HPA) was i...

Due to its super-acidity and ability of its bulk to react following a pseudo-liquid mechanism, the Keggin H3PW12O40 heteropolyacid attracts more and more attention as catalyst for the gas phase methanol-to-DME reaction. However, in its pure state, H3PW12O40 has a very low surface area (typically 5-10 m²/g), which limits the accessibility of its inn...

H3PW12O40 is a Keggin heteropolyacid (HPA) that nowadays attracts more and more attention as catalyst for the gas phase dehydration of methanol to dimethylether. Here, we investigate its performance in the latter reaction at 250-300 °C, namely under coking conditions. Actually, we address the question whether the elsewhere elucidated procedure allo...

Heteropolyacids (HPAs) are metal-oxygen clusters which are nowadays widely used in acid catalysis. Indeed, as they possess a very strong Brönsted acidity, approaching the super-acid region, they generally allow performing reactions at lower temperatures than conventional catalysts. In the present paper, we use in situ/operando Raman spectroscopy to...

Operando Raman spectroscopy is used here to enlighten crucial and yet unconsidered aspects of the catalytic behavior of Keggin heteropolyacids (HPAs) in the gas phase dehydration of methanol to dimethylether (DME). On one hand, HPAs are since a long time claimed as being able to absorb methanol into their bulk, but on the other hand this feature is...

Characterizing catalysts under working conditions is crucial to understand and to optimize their behavior and performance. However, when Raman spectroscopy is used, attention has to be paid to laser-induced artefacts. While laser irradiation is often claimed to lead to a temperature gradient between the integral catalyst bed and the sampling point,...