Time-dependent carbide phase formation in palladium nanoparticles

Dehydrogenation of Ethylene on Supported Palladium Nanoparticles: A Double View from Metal and Hydrocarbon Sides

“…The observed decomposition of ethylene with the formation of carbide correlates with a number of previous reports [ 29 , 30 , 31 , 33 , 36 , 37 , 38 , 39 , 40 ]. The lattice expansion at 50 °C is, however, significantly reduced, in terms of both the kinetics and saturated values compared to the studies performed at higher temperatures [ 40 ]. The collection of high-quality synchrotron data was of utmost importance for highlighting these small changes.…”

“…In addition, the intensity of the first shell peak decreases due to the increasing Debye–Waller factor (see Figure S1 and Table S1 in the Supplementary Information ). Both observations are indicative of palladium carbide formation [ 34 , 36 , 38 , 40 ]. It should be noted that the coordination numbers are stable along the whole series of collected spectra indicating the stability of Pd particles (see Figure S1 and Table S1 in the Supplementary Information ).…”

“…In the recent works of Bowker [ 29 , 30 , 31 ], it was highlighted that under industrially relevant pressures on real catalysts, the processes are different from that on ideal surfaces and high-vacuum conditions, which are typical for surface science studies. In addition, palladium can easily form carbide phase in the presence of hydrocarbons [ 29 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 ], which affects its catalytic properties. For this reason, the application of bulk-sensitive structural methods in addition to surface-sensitive ones is important to understand the structural evolution of the metal.…”

Hydrogenation of ethylene over palladium: evolution of the catalyst structure byoperandosynchrotron-based techniques

“…In the same work it was also observed that in presence of hydrocarbons β-PdH is formed at much higher partial pressures of hydrogen comparing to Pd-H phase diagram obtained in pure hydrogen, 12 which indicates that an investigation of Pd-H/Pd-C phase diagram under different partial pressures of hydrogen and hydrocarbon molecules is required. In our recent works, formation of palladium carbides was observed in the presence of acetylene, 13-15 ethylene 14,16,17 and under reaction conditions, [16][17][18] which also highlighted irreversible changes in the catalyst structure in the time scales from minutes to hours. In the current work, we performed operando time-resolved study of supported palladium nanoparticles during ethylene hydrogenation by combined Pd K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy, X-ray absorption near edge structure (XANES) spectroscopy, X-ray powder diffraction (XRPD) and mass spectrometry.…”

In Situ Time-Resolved Decomposition of β-Hydride Phase in Palladium Nanoparticles Coated with Metal-Organic Framework

“…Palladium is well-known for its ability for dissociative adsorption and storage of hydrogen [1]. The hydrogen storage capacity and kinetics of hydrogen adsorption and desorption are strongly affected by the particle's size and shape [2][3][4][5][6][7][8], which is an important parameter for catalytic applications [8][9][10][11][12][13][14]. Bulk palladium materials exhibit a sharp phase transition from αto β-hydride, resulting in a characteristic plateau in the pressure composition isotherm [1].…”