Effect of retained chlorine in ENCAT™ 30 catalysts on the development of encapsulated Pd: insights from in situ Pd K, L₃ and Cl K-edge XAS

Abstract

In situ X-ray absorption spectroscopy (XAS) and Pd K, L III , and Cl K-edges shows that Cl can be present in significant amounts in ENCAT™ 30 catalysts and that it can severely retard Pd nanoparticle (NP) development in flowing solvents. We also show that whilst polymeric encapsulation protects the Pd against solvent induced agglomeration of Pd nanoparticles the evidence suggests it does not prevent the formation PdH x through reaction with the aqeous ethanol solvent, and that, as received, ENCAT™ 30 NP catalysts are not, for the most part, comprised of nanoparticulate Pd 0 irrespective of the presence of Cl.

Controlling the Production of Acid Catalyzed Products of Furfural Hydrogenation by Pd/TiO2

“…The presence of unreduced Na 2 PdCl 4 can be discounted as full reduction of the salt is shown in the UV‐Vis spectra (Figure S2d). We rationalise that this Cl signal arises from adsorbed chloride on the Pd surface as others have also reported [74,75] . Between samples PdWPA and PdMeP, this feature has comparable intensity, suggesting a similar amount of surface Cl, however we see no selection to the acid catalysed product for PdMeP.…”

Operando Exploring and Modulating Phase Evolution Chemistry from MAX to MXenes in Molten Salt Synthesis

“…Cl K -edge X-ray absorption near-edge structure (XANES) measurements were first performed to identify the chemical state of Cl groups on MXenes (Figure a). An observable pre-edge absorption peak is observed, which arises from the transition between the Cl 1s orbital and the p-d hybrid orbital. , The normalized peak intensity can be used to analyze the covalency of metal-Cl bonds . The intensity of the pre-edge absorption peak is reduced in p-Nb 2 CT x compared with that of Nb 2 CT x , reflecting a lower covalency of Nb–Cl bonds in p-Nb 2 CT x .…”

On the dual role of the reactant during aqueous phase hydrodechlorination of trichloroethylene (HDC of TCE) using Pd supported on swellable organically modified silica (SOMS)

“…When this sample was soaked in solution containing HCl and TCE, changes occurred in the bulk of Pd particles giving rise to Pd-Cl interactions. This can be seen by the presence of additional features obtained in the k 2 weighted FT magnitudes corresponding to Pd-Cl bonds [68]. Formation of Pd-Cl bonds (CN: 2.1) was accompanied by a decrease of Pd-Pd CN (CN for pristine: 8.5 and CN for HCl and TCE soaked sample: 6.5).…”