The application of nanosized palladium catalysts has gained growing importance over the last few years. Palladiumbased catalytic methods for fine organic synthesis permits the replacement of traditional labor-consuming techniques in multi-step organic syntheses and provides an improvement from the standpoint of cost and environmental impact. The use of activated carbon "Sibunit" as a substrate for catalysts has been fostered by the substrate's high surface area,
chemical inertness both in acidic and basic media, and at the same time by the absence of very strong acidic centers on its surface which could promote undesirable side reactions during the catalytic run. A conversion of alpha-pinene derivatives to commercial biologically active compounds and fragrances as well as sun screens with ultra violet filtering properties, involves a catalytic hydrogenation as a key intermediate step. The aim of the present work is to clarify the factors favoring the dispersion of Pd metal on carbon. The effect of reduction temperature and pretreatment of the carbon surface on metal size during preparation of Pd on "Sibunit" catalysts for selective verbenol conversion was studied. The
electron microscopy method (TEM) was used to show the influence on Pd metal dispersion of carbon surface oxidation by the oxidant H2O2, HNO3. The catalytic activity of Pd/C catalyst samples in verbenol hydrogenation reaction was determined. Kinetic peculiarities of verbenol hydrogenation over the most active catalyst sample were obtained.
Nanosized carbon fibers are of great importance due to its numerous technological applications. One of its disadvantages is low mechanical strength. This problem could be solved by incorporation of carbon fibers into cavities or channels of ceramic monoliths with foam or honeycomb structure. In the present work the experience of preparation of uniform carbon layer consisting from nanosized fibers onto ceramic monoliths with different geometry will be presented. Carbon fibers were produced by catalytic pyrolysis of methane over nanosized metal particles supported over ceramic monolith. Variation of preparation conditions permits to obtain carbon fibers with different density and thickness.
Last years nanosized gold particles attract much attention as a component of industrially perspective catalysts for some reactions as CO oxidation, NO reduction etc. We studied several systems including gold based on different synthetic zeolites pure or doped with another metals (Fe, Na). It was shown by different techniques (XPS, UV-Vis spectroscopy, TPR) that intrinsic properties of zeolites used and gold system preparation method influence significantly on the contribution of different gold species (ions, clusters and particles). For mixed Au-Me-zeolites activity level and dynamic of CO conversion with time in steam and temperature depends on nature of zeolite and specificity of Au-Me interaction. All binary metal systems were found to be activated in different degree during catalytic activity test due to mutual interaction of gold with second metal. Extremely high level of CO conversion and low dependence of activity on temperature was observed for Au- Fe- H- and Na-Y zeolites. The change in contribution of gold nanoparticles was observed after sample contact with CO.
Copper based catalysts are of great importance as catalysts for NO removal from exhaust industrial gases. Earlier authors have shown that NO reaction with acetone oxime (AO) is the rate determining step of NO catalytic reduction by propane over Cu-ZSM-5 catalyst at temperatures below 300oC. Aim of the present work is to clarify the peculiarities of acetone oxime coordination over surface of H-ZSM-5 zeolite and that doped with Cu(II) and Cu(I)-cations. We studied AO coordination in CCl4 solutions and then data obtained were used for analysis of spectra of AO adsorbed on pure zeolite and that dopped with Cu (I) and Cu (II) cations. It was shown that there are monomers and several associates of AO in CCl4 solution differing in size and type of bonding with their own characteristic bands in IR spectra. The spectrum of acetone oxime adsorbed on pure zeolite includes non symmetrical band at 1710 cm-1 due to AO strongly bonded with zeolite surface through H-bond. There are four AO adspecies on zeolite dopped with copper with two different types of AO coordination to Cu(I) or to Cu(II) cations: one with participation of O atom and another one with N atom. Complexes of AO with Cu(I) ions are much more stable then those with Cu(II) ions.
Cu-mordenites catalysts are among the most active available for de-NOx at moderate temperatures. Silica-alumina molar ratio of mordenite supports strongly affects conversion efficiency for NOx. Copper mordenites' rapid deactivation by water has led us to investigate the effects of adsorbed water on framework and extra-framework ions, mainly using NMR of 27Al and 1H. Adsorbed water content has been monitored and controlled in mordenite samples via TGA, as well as by vacuum calcination. Several NMR measurements have been performed to aid in the interpretation of spectra, including variable pulse-delay spin echo and 1H-27Al TRAPDOR. A number of surface characterization techniques have been applied to both H- and Cu-mordenites. Catalytic experiments showed that the reduction of NOx to N2 and O2 by hydrocarbons reach 95-98 % depending on the catalyst composition.