Jan Petryk

The properties of cobalt oxide catalyst for ammonia oxidation

Abstract A cobalt oxide catalyst for ammonia oxidation of high and stable activity and selectivity has been obtained and tested in a fluidized bed laboratory reactor. Its active component is Co 3 O 4 . It has been found that much less nitrous oxide is produced in ammonia oxidation on this catalyst than on platinum. The macrostructure of the cobalt catalysts, and especially the presence of mesopores of diameter 3 /g. A hypothetical model has been presented to explain the effect of the catalysts macrostructure on its properties.

Cobalt oxide catalysts for ammonia oxidation activated with cerium and lanthanum

Abstract The effect of cerium and lanthanum oxides in cobalt oxide catalysts for both activity and selectivity in ammonia oxidation was studied. The molar ratios of Ce/Co and La/Co in the catalysts were 0.02. All the catalysts were characterized by XRD. The activity was measured in a fixed bed reactor at a temperature range of 720–820°C. Cerium oxide proved to be a more efficient promoter than lanthanum oxide, both being advantageous. The selectivity of ammonia oxidation to NO over Ce-containing sample was even as high as 97.7% and the selectivity to N2O was as low as 0.5%.

Gas Temperature in an Ozonizer. The Computer Modeling of an Actual Discharge System

Dielectric barrier discharges are commonly used for ozone synthesis. The main reactions of this process proceed in the microdischarge channels in which the variable temperature occurs. The temperature in the discharge gap was modeled. The dynamics of a gas temperature inside the discharge gap changes were presented.

Studies on DBD in Oxygen. Dynamics of the Gas Cooling in Microdischarge Channel

Changes of the gas temperature inside the isolated microdischarge channel were analyzed. The rate of decrease of the initial temperature up to the level of the average gas temperature in the gap has been shown. The duration of the elevated gas temperature in the microdischarge channel and where the ozone is decomposed have been explained. The gas-expanding effect in the microdischarge volume has been presented. Computer visualization of the microdischarge channel in the discharge gap is presented.

Computer Modeling of Gas Temperature in the Ozonizer Gap. Effects Generated by a Single Microdischarge

During the ozone synthesis under dielectric-barrier-discharge conditions, the main reactions proceed in the microdischarge channels in which variable temperature occurs. In such dynamic conditions, a balance between ozone synthesis and decomposition reactions is established. The changes of temperature in a single microdischarge channel were modeled. It was found that the temperature in the middle of the channel decreases quite fast. Moreover, the changes in temperature significantly influence the gas velocity and intensify the gas mixing.

Effect of Texture of Cobalt Oxide Catalyst on its Properties in Ammonia Oxidation

ABSTRACT The selectivity of cobalt oxide catalysts with different porosity characteristics was studied in ammonia oxidation process. It has been found that the selectivity of NH 3 oxidation to NO depends significantly on the total porosity and pore size of the catalyst. An advantageous effect of large pores of several micrometers was observed. Low porosity of catalysts favoured the formation of N 2 O. The presence of fine pores stimulates the formation of N 2 molecules.

Cobalt catalyst for ammonia oxidation modified by heat treatment

Abstract Heat treatment of the cobalt oxide catalyst is a substantial condition for obtaining theproduct of high activity and of sufficient mechanical strength. It was shown that the porous structure of catalyst grains, produced in the course of heat treatment, is one of the parameters responsible for catalytic activity. The volume of the coarse pores (0.5–1 μm in radius) is of primary importance for the performance of the catalyst.