Ireneusz Kocemba

Relationship between the catalytic and detection properties of SnO2 and Pt/SnO2 systems

Semiconductor gas sensors based on metal oxides have been widely accepted as an important tool for the detection of different gases in air. An understanding of all the mechanisms related to such detection is essential in order to improve the sensitivity and selectivity of these gas detectors. This paper considers the mechanism of detection by semiconductor oxide gas sensors in terms of catalytic reactions described by Rideal–Eley and Langmuir–Hinshelwood mechanisms. Some relationships were discussed between the catalytic and detection properties of SnO2 and Pt/SnO2 systems used on the one hand as catalysts of low-temperature CO oxidation and on the other hand as sensors of CO in air.

Sensors Based on SNO2 As a Detector for CO Oxidation in Air

This work describes properties of sensors based on SnO2 , which were used as detectors in the temperature-programmed surface reaction (TPSR) of CO oxidation. Usually, the detection in temperature-programmed processes is realized by using TCD (katharometer) or a mass spectrograph. In our work we present preliminary results which show that the sensors manufactured from SnO2 can also be used to this aim.

Effect of Cobalt Addition on the Activity of Nanocrystalline Iron Catalysts in the Cracking of Methane Reaction

The effect of cobalt addition on the activity of nanocrystalline iron catalysts in the cracking of methane reaction is studied. The composition and properties of the catalyst were determined by inductively coupled plasma optical emission spectrometry, X-ray diffraction and temperature-programmed reduction methods. The activity of the catalyst in the reaction was defined by measuring the concentration of hydrogen, which was determined by gas chromatography. After cracking of methane reaction, the sample coated with a carbon deposit was examined with scanning electron microscope with energy-dispersive spectrometer. The reaction yield in the direction of hydrogen acquisition for the catalyst with cobalt was above 80%, and after the regeneration process, the catalyst was still active at a very high level. The reaction path for the catalyst without the cobalt addition was performed in two steps, and the catalyst after the reaction was non-regenerative.

CO and H2 oxidation over Pt/BaSnO3 catalysts

This work reports the results of the studies on oxidation of carbon monoxide and H2 over Pt supported on barium stannate (BaSnO3—perovskite type oxide). The composition and properties of Pt/BaSnO3 catalysts were characterized by X-ray diffraction (XRD), time-of-flight secondary ion mass spectrometry (TOF–SIMS), H2 and CO chemisorption, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM–EDS) and tested in the reactions of carbon monoxide and hydrogen oxidation. It was stated that platinum strongly interacts with BaSnO3. The catalytic activity and adsorption properties of Pt/BaSnO3 catalysts are determined by these interactions. The presence of different species (which generally can be labelled as [(Pt)BaSnO3]) resulting from platinum and BaSnO3 chemical interaction was found by the TOF–SIMS on surface of Pt/BaSnO3 catalysts. The mechanism of CO and H2 oxidation over Pt/BaSnO3 catalysts was discussed in the light of strong interactions between Pt and BaSnO3.

Nanostructured forms of carbon deposit obtained during cracking of methane reaction over nanocrystalline iron catalysts

During catalytic cracking of methane reaction, different carbon nanostructures can be formed. This paper shows the results of a characteristic nanostructured carbon deposit obtained during cracking of methane reaction over nanocrystalline iron catalysts with or without cobalt addition. The properties of the carbon deposit were determined by X-ray diffraction, scanning electron microscope with energy dispersive spectrometer equipment, thermogravimetry-differential thermal analysis coupled with mass spectrometry, time-of-flight secondary ion mass spectrometry analysis and surface area analysis (Brunauer-Emmett-Teller isotherm [BET]). Significant differences in the morphology and properties of the obtained carbon were found. The mechanism of the formation of carbon nanostructures for both iron catalysts is proposed.