Investigation of a traditional catalyst by contemporary methods: Parallel electron spectroscopic and catalytic studies on Pt black

Abstract

Results of electron spectroscopy (XPS and UPS) of platinum black catalyst measured in various states of the catalyst have been summarized. XPS showed up to almost 50% carbon and up to 20% oxygen on a sample stored in air. These, however, had almost no influence on the chemical state of Pt, except for the appearance of minor surface oxide. A Pt purity of ~90% could be reached by regeneration with O 2 and H 2 . The C 1s peak contained several components from individual C atoms to graphitic and polymeric hydrocarbon layers. Thus, the active catalyst was not clean Pt but metallic Pt; the impurities exerting little influence on catalytic activity. Regeneration and deactivation led also to slight structural rearrangement, as detected by XRD. Intentional deactivation with hydrocarbon-hydrogen mixtures was monitored by XPS, UPS and catalytic tests. Correlation was found between catalytic activity and selectivity in hexane reaction and the amount -and also the chemical state -of carbon accumulated during deactivating runs. A short summary of electron spectroscopy of supported Pt catalysts is also given. The main underlying idea regards solid catalyst and reactants as a dynamic system, including also solid-state changes of the former.

Synchrotron-radiation-stimulated etching of polydimethylsiloxane using XeF2as a reaction gas

“…After etching, a new peak appeared at 285.7 eV, which is assigned to the hydrogen-containing carbon material (C x H x ) (Paá l & Schlö gl, 2009 Figure 6 Optical microscope picture of the pattern formed on the PDMS substrate surface by 10 min of SR etching using the copper mesh with 400 wires per inch as a contact mask with the conditions of 0.4 torr XeF 2 gas and 110 mA ring current. The etching chamber was evacuated for about 2 h before etching.…”