T. Paryjczak

ToF-SIMS application in the visualization and analysis of fingerprints after contact with amphetamine drugs

Time-of-flight secondary ion mass spectrometry was applied in forensic research for characterization, visualization and analysis of fingerprints left after the fingers were contaminated by traces of drugs: amphetamine (AF), methamphetamine (MA) and methylenedioxymethamphetamine (MDMA; ecstasy). Experimental work was carried out using four kinds of bases (steel, aluminium, brass and glass) on which fingerprints were imprinted. The results of our preliminary studies have demonstrated that the ToF-SIMS technique can be a powerful tool in chemical investigations of fingerprints and detection of traces of substances, which do not exist in natural skin extraction, but can be found at the crime scene.

Interactions between oxygen, hydrogen and supported rhodium over a wide temperature range : I. Oxygen and Hydrogen adsorption

Abstract Interactions of oxygen and hydrogen with the surface of rhodium—alumina catalysts within the temperature range −80 to 700° were examined by pulse gas chromatography. Oxygen and hydrogen chemisorptions were carried out on “clean” rhodium surfaces and titrations of the oxidized surface with hydrogen were performed together with those of the inverse reaction, i.e., titration of the reduced surface with oxygen, In site of many probelms which are discussed, the results of oxygen and hydrogen chemisorption at ambient temperature can be used for the determination of the surface area of rhodium. It was found that above 200° oxygen considerably penetrated the rhodium lattice forming stable suboxides, and above 500° the product of oxidation was rhodium(III) oxide (Rh2O3).

Characterization of Ru/CeO2-Al2O3 catalysts and their Performance in CO2 Methanation

Ru/Al2O3 and Ru/CeO2-Al2O3 samples were used as catalysts in CO2 methanation. The catalysts were characterized by temperature-programmed reduction (TPR) and X-ray diffraction. The promoting effect of ceria on the catałytic activity of the catalysts under study in CO2 methanation was observed.

Physico-Chemical and Catalytic Study of the Co/SiO2 Catalysts

This paper is focused on the physico-chemical and catalytic properties of Co/SiO2 catalysts. Silica-supported cobalt catalysts were prepared by sol-gel and impregnation methods and characterized by BET measurements, temperature programmed reduction (TPRH2), X-ray diffraction (XRD), and thermogravimetry-mass spectroscopy (TG-DTA-MS). The sol-gel method of preparation leads to metal/support catalyst precursor with a homogenous distribution of metal ions into bulk silica network or on its surface. After drying the catalysts were calcined at 500, 700, and 900°C. The reducibility of the supported metal oxide phases in hydrogen was determined by TPR measurements. The influence of high temperature—atmosphere treatment on the phase composition of Co/SiO2 catalysts was investigated by XRD and TG-DTA-MS methods. At least five crystallographic cobalt phases may exist on silica: metallic Co, CoO, Co3O4 , and two different forms of Co2SiO4 cobalt silicate. Those catalysts in which cobalt was chemically bonded with silica show worse reducibility as a result of strongly bonded Co-O-Si species formed during high-temperature oxidation. The TPR measurements show that a gradual increase in the oxidation temperature (500–900°C) leads to a decrease in low-temperature hydrogen reduction effects (<600°C). The decrease of cobalt oxide reduction degree is caused by cobalt silicate formation during the oxidation at high temperature (T ≤ 1000°C). The catalysts were tested by the reforming of methane by carbon dioxide and methanation of CO2 reactions.

Interactions between oxygen, hydrogen and supported rhodium over a wide temperature range : II. Titration reactions in the oxygen—hydrogen system and evaluation of dispersion of rhodium—alumina catalysts

Abstract The application of ther results of titration in the oxygen—hydrogen system to the determination of metal surface seems to be influenced by water, the product of the titration process. The dependence of the titration results on the number of successive titration cycles is discussed in terms of a proposed blocking mechanism, according to which water from the support gradually blocks part of the metal surface. The results of hydrogen and oxygen chemisorption and hydrogne—oxygen titrations are compared with respect to rhodium surface area determination.

Chemisortion method for the determination and removal of trace amounts of oxygen in unreactive gases

Summary An effective purification of carrier gas from trace amounts of oxygen and a simple determination of trace amounts of oxygen in unreactive gases have been achieved with the use of the catalysts Pt/γ-Al203 and Pd/γAl2O3.

Temperature-programmed reduction and oxidation of bimetallic catalysts Rh−Ag/Al2O3

Investigations of temperature-programmed reduction and oxidation of bimetallic catalysts Rh−Al2O3 seem to indicate that there are no strong interactions between rhodium and silver. Bimetallic catalysts rather show the additive properties of individual components, i. e. rhodium and silver.AbstractИсследования температурно-программированного восстановления или окисления биметаллических катализаторов Rh−Al/Al2O3 указывают на отсутствие сильного взаимодействия между родием и серебром. Биметаллические катализаторы скорее обладают аддитивными свойствами индивидуальных компонентов, а именно родия и серебра.

Interaction of oxygen and hydrogen with platinum in pulse gas chromatography

Abstract The interaction of oxygen and hydrogen with the surfaces of platinum black, platinum-silica and platinum-alumina catalysts within the temperature range 196–970°K was examined by pulse gas chromatography. Chemisorption of oxygen and hydrogen was carried out on a “clean” platinum surface and titrations of the oxidized surface with hydrogen were performed together with those of the reverse reaction, i.e., titration of the reduced surface with oxygen. We were able to define the extent of slow, reversible hydrogen sorption within a wide temperature range, desorption of oxygen from the platinum surface and the formation of an oxide multilayer at higher temperatures. The results indicate that the stoichiometries of the surface interactions between platinum and oxygen and between platinum and irreversibly chemisorbed hydrogen are the same and approximate to unity: O/Pt2 ≈ H/Pt5 ≈ 1. The temperature range 300–570°K is suitable for determining platinum dispersions by means of oxygen and hydrogen chemisorption.

Investigation of the rhenium—oxygen system within the wide temperature range

Abstract Interactions between oxygen and metallic rhenium surface and Re Al 2 O 3 catalysts have been investigated within the wide temperature range from 77 to 773°K in static and dynamic conditions. The contributions of reversible and irreversible oxygen sorption have been determined. Three temperature ranges of different oxygen—rhenium interactions have been distinguished: superficial (298–473°K), bulk oxidation (473–673°K), and above 673°K when ReO3 is formed. This paper discusses the conditions of carrying out oxygen chemisorption on rhenium catalysts in order to determine rhenium selective surface.

INFLUENCE OF CALCINATION AND LITHIUM PROMOTION ON THE SURFACE PROPERTIES OF OXIDE SUPPORTS

Thermal treatment and the addition of lithium influence the surface area of the oxides SiO2, Al2O3 and MgO. A calcination temperature ≥1073 K causes a significant decrease of the surface area of SiO2 and Al2O3; the same is not observed in case of MgO. Systems Li/MgO and Li/SiO2 are characterized by a much smaller specific surface area than pure oxides thermally treated at the same temperature.