Study on the effect of hydrocarbon structure on the reactivity of the three-way catalytic converter

Abstract

The effect of hydrocarbon structures on reduction of nitric oxide and oxidation of carbon monoxide and hydrocarbons on the palladium-rhodium catalyst supported on aluminum-cerium-zirconium oxide was examined with fixed-bed flow reactor using synthetic gas. As regards olefinic hydrocarbons, the lower the number of carbon atoms, the higher the rate of reduction of nitric oxide, the lower the number of carbon atoms, the greater the rate of oxidation of hydrocarbons and carbon monoxide. Olefinic hydrocarbons have a π bond and are highly adsorbed on catalytic sites. Consequently, it may be hypothesized that if the number of carbon atoms increases, the adsorption ability becomes too high and the reactivity of the hydrocarbons decreases. On the other hand, for paraffinic hydrocarbons, the greater the number of carbon atoms, the greater the rate of reduction of nitric oxide, and the more carbon atoms there are, the higher the oxidation rate of the hydrocarbon. In the case of paraffinic hydrocarbons, there are only σ bonds and less adsorption on the catalyst site, it is therefore assumed that the greater the number of carbon atoms, the greater the reactivity of the hydrocarbon. The results of the effects of these hydrocarbon structures on the overall three-way catalytic reaction activity provide an indicator of the development of new catalysts.