Slavcho Rakovsky

Ozone decomposition on Ag/SiO2 and Ag/clinoptilolite catalysts at ambient temperature

Silver modified zeolite (Bulgarian natural clinoptilolite) and Ag/silica catalysts were synthesized by ion exchange and incipient wet impregnation method respectively and characterized by different techniques. DC arc-AES was used for Ag detection. XRD spectra show that Ag is loaded over the surface of the SiO(2) sample and that after the ion-exchange process the HEU type structure of clinoptilolite is retained. UV-VIS (specific reflection at 310 nm) and IR (band at 695 cm(-1)) spectroscopy analysis proved that silver is loaded as a T-atom into zeolite channels as Ag(+), instead of Na(+), Ca(2+), or K(+) ions, existing in the natural clinoptilolite form. The samples Ag/SiO(2) and Ag-clinoptilolite were tested as catalysts for decomposition of gas phase ozone. Very high catalytic activity (up to 99%) was observed and at the same time the catalysts remained active over time at room temperature.

Ozone Decomposition Reaction over α-Alumina-Supported Silver Catalyst: Comparative Study of Catalytic Surface Reactivity

An alumina-supported silver composite system has been investigated in the reaction of heterogeneous catalytic ozone decomposition. Perlite loaded with silver and silver modified zeolites have also been tested as catalysts for gas phase conversion of ozone to molecular oxygen. The catalysts have been activated by calcination and the changes occurring on the catalytic surface as a result of the reaction have been characterized in details using XPS. The SEM analysis has revealеd the role of surface morphology in the process of ozone decomposition on the surface of Ag/α-Al2O3 catalyst. A catalytic cycle is proposed that supports the hypothesis about the important role of the peroxide species as intermediates participating in the process and catalyzing the complete ozone conversion into molecular oxygen. It has been found out that the maximum conversion degree, achieved with the alumina-supported silver system, is up to 90%.

Plasma-Chemical Synthesis of Nanosized Powders – Nitrides, Carbides, Oxides, Carbon Nanotubes and Fullerenes

In this article the plasma-chemical synthesis of nanosized powders (nitrides, carbides, oxides, carbon nanotubes and fullerenes) is reviewed. Nanosized powders - nitrides, carbides, oxides, carbon nanotubes and fullerenes have been successfully produced using different techniques, technological apparatuses and conditions for their plasma-chemical synthesis.