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Annales UMCS, Chemistry (v.65, #-1)
Synergistic effects in hydrodechlorination of organic compounds catalyzed by metals by M. Bonarowska; A. Śrębowata; Z. Karpiński; (pp. 1-8).
The search for the most suitable hydrodechlorination catalysts should consider both the C-Cl bond strength in a molecule subjected to reaction and the metal-chlorine bond, which should be neither too strong nor too weak. An improvement of Pd- and Pt-based catalysts can be achieved by alloying with metals which bind chlorine even less strongly, e.g. with gold. Addition of platinum to palladium would also be beneficial because of metal-chloride bond energy considerations. Analogous effects occur in the hydrodechlorination of dichlorodifluoromethane and 1,2-dichloroethane, the molecules characterized by stronger carbon-chlorine bonds.
Transmission Electron Microscopy as indispensable tool for imaging and chemical characterization of heterogeneous catalysts by L. Kępiński; (pp. 9-19).
Transmission Electron Microscopy (TEM) and its mutation Scanning Transmission Electron Microscopy (STEM) is one of the most important methods providing unique information on structure and chemistry of solid catalysts at length scale down to level. The principal reason is its high spatial resolution (below 0.1 nm) but also universality, i.e., ability of observation of both images and diffraction patterns of individual nanometer size objects. Recent advances in TEM in particular application of image and beam correctors, possibility of studying specimens at non vacuum conditions (environmental TEM) and possibility of dynamic (time resolved) studies even further broadened the applicability of the method in catalysis.
Decomposition of ethylene on iron catalyst to obtain carbon nanotubes and the way of their purification by I. Pełech; K. Owodziń; U. Narkiewicz; (pp. 20-30).
This paper describes preparation and characterization of carbon nanotubes obtaining using ethylene as a carbon source and iron as catalyst. Additionally purification procedure of carbon nanomaterials is presented. Purification was conducted in two stages. In the first one hydrogen or air was used in order to gasify unwanted carbon forms. In the second one - various reactants (nitric, hydrochloric or nitro-hydrochloric acids) were applied to remove metal particles. Obtained materials were characterized using X-ray diffraction, transmission electron microscopy and thermogravimetry.
Surface modification of bioceramics by PEG grafting by K. Adamska; M. Woźniak; A. Voelkel; (pp. 31-44).
Surface modification of Hydroxyapatite (HAp) and β-Tricalcium phosphate (β-TCP) powders was performed using hexamethylene diisocyanate (HMDI) as a coupling agent. Polyethylene glycol (Mw = 2000) was grafted to the surface of these ceramic materials. Different methods were used to characterize modified surfaces. Fourier transform infrared (FT-IR) and Attenuated Total Reflection Fourier Transform Infrared (FTIR/ATR) technique analyses confirmed the modification reaction on HAp and β-TCP surfaces. BET isotherm analysis showed the changes in textural properties of materials after modification. Elemental analysis was performed to confirm a presence of selected elements from modifier and coupling agent. Examination of dispersion stability of materials in different solvents show better stability for samples of β-TCP than HAp.
Studies of Zn-Al-Ce mixed oxides as catalysts for diesel soot combustion by L. Chmielarz; A. Węgrzyn; A. Kowalczyk; S. Witkowski; R. I. Walton; A. Matusiewicz; (pp. 45-54).
A series of Zn-Al-Ce mixed oxides was synthesized by a co-precipitation method. The obtained samples were characterized with respect to composition (XRF), structure (XRD, FT-IR) and texture (BET). Zn-Al-Ce mixed oxides were tested as catalysts of diesel soot combustion. The best catalytic activity was found for Zn2Ce oxide system, which operated in the temperature range of 350-500°C.
A study of iron catalyst for ammonia synthesis by electron spectroscopy methods by W. Arabczyk; D. Moszyński; M. Dłużewska; (pp. 55-67).
A concise review of former studies into iron catalyst using electron spectroscopy methods is presented. A model of iron catalyst's surface, the so-called double layer model is presented. On the basis of this model both a method of determining surface content of a real iron catalyst and a method of determining the rate of potassium surface diffusion were developed. A double layer model was used to interpret thermal stability loss of potassium atoms on iron surface subjected to sulphur compounds' exposure.
Determination of the active phase structure in CuO/γ-Al2O3 catalysts by TPR kinetic model discrimination by P. Kuśtrowski; A. Białas; J. Surman; B. Dudek; (pp. 68-78).
The results of temperature-programmed reduction with hydrogen of alumina supported copper oxide catalysts were used to find the best model describing the kinetics of Cu ions' reduction. On the basis of the rate determining step of this reaction the structure of copper oxide was revealed. This kinetic approach was compared with BET and UV-vis-DRS results. The catalytic activity of various copper oxide forms was tested in toluene combustion.
The effect of calcination temperature on properties and activity of Cu/ZnO/Al2O3 catalysts by P. Kowalik; W. Próchniak; (pp. 79-87).
The paper presents the results of the investigation on the influence of calcination temperature of Cu-Zn-Al catalyst precursor, on physicochemical properties and catalytic activity for water gas shift reaction. A model precursor of chemical composition corresponding with a typical commercial catalyst and prepared by coprecipitation method was studied. It has been shown that the temperature of calcination step determines the surface properties of the final catalyst, the active phase dispersion, and thus significantly affects the catalytic activity.
The study on alkali-promoted Co-Mo/Al2O3 catalysts for water-gas shift process by K. Antoniak; P. Kowalik; J. Ryczkowski; (pp. 88-95).
The following contribution presents the results of studies on the effects of alkali metals on the physicochemical properties and the effectiveness of a Co-Mo/Al2O3 catalyst for the water gas shift reaction. It has been shown that the addition of alkali metals modifies the properties of Co-Mo catalysts, resulting in a significant increase in activity of catalysts in water gas shift reaction. The greatest effect was observed in the case of sodium-promoted reaction.
Effectiveness diffusion coefficient in nickel catalyst grain determined by measurements of catalytic reaction rate
by K. Stołecki; K. Michalska; R. Narowski; A. Gołębiowski; (pp. 96-99).
The influence of gold on the properties of silica mesoporous materials by W. Gac; S. Pasieczna-Patkowska; L. Kępiński; (pp. 100-120).
The properties of gold modified silica mesoporous materials were investigated on the successive preparation stages. Samples were obtained by the direct introduction of HAuCl4 aqueous solution to the synthesis mixture of silica. It was stated that partial substitution of -Cl with -OH ligands occurred in the diluted solutions of HAuCl4. The replacement of -Cl with -Br groups in gold complexes took place in the synthesis mixture containing hexadecyltrimethylammonium bromide surfactant molecules. It was found that gold species influenced the removal of organic templates from the channels of silica materials. Pore arrangement was not strongly distorted by the presence of small amounts of gold. Heat treatment led to the pronounced changes of the nature of gold species.
Spectroscopic studies of alumina supported nickel catalysts precursors: Part II - catalysts prepared from alkaline solutions by S. Pasieczna-Patkowska; J. Ryczkowski; (pp. 121-131).
Nickel alumina supported catalysts were prepared from alkaline solutions of hexaamminenickel nitrate by CIM and DIM methods (classical and double impregnation, respectively). The catalysts exhibited different nickel species due to the existence of various metal-support interaction strengths. As a consequence, the reducibility and other surface properties changed as a function of the preparation method. The aim of this work was to study the interaction between the metal precursor and alumina surface by means of FT-IR (Fourier transform infrared) and FT-IR/PAS (FT-IR photoacoustic spectroscopy).
Scientific co-operation with professor Borowiecki by J. Ryczkowski; (pp. 132-154).
In present paper there will be discussed examples of author's scientific co-operation with professor Borowiecki. Generally all of them are from the area of heterogeneous catalysis with a feedback to chemical technology and an environmental protection.
Syntheses, structures and properties of halogenanilides derivatives of trichlorophenoxyacetic acids by B. Tarasiuk; (pp. 155-168).
The results of the study on the syntheses and properties of halogenanilides derivatives of trichloro- phenoxyacetic acids are presented. Compounds were synthesized during the reaction of trichlorophenoxyacetic chlorides with halogenaniline and N, N-diethylaniline or trichlorophenoxyacetic acids with halogenanilines and phosphorus oxychloride. The chemical derivatives were isolated with high yield and identified on the basis of elemental analysis, FTIR, 1H NMR and 13C NMR spectroscopy as well. Their physico-chemical properties were examined, along with their fungicidal, insecticidal, acaricidal and herbicidal activity. It was found that the highest herbicidal activity characterizes the derivatives of 2,4,5-trichlorophenoxyacet-4-fluoroanilide, 2,4,5-trichlorophenoxyacet-4-chloro-3-(trifluoromethyl) anilide, 2,4,5-trichlorophenoxyacet-3-(trifluoromethyl)anilide and 2,4,5-trichlorophenoxyacet-4-chloro-3-fluoroanilide.