Enhancement of Combustive Removal of Soot at Low Temperatures (∼ 150 °C) Using Ozone as an Oxidant and Potassium-Substituted Lanthanum Manganite as a Catalyst

Ozone (O-3) is a strong oxidant, which is able to oxidize carbonaceous solid soot even at ambient temperature. In this study, we found that the ozone-induced oxidation of soot was noticeably enhanced in the range 100-150 degrees C when La1-xKxMnO3 (x = 0, 0.1, 0.25) was used as a catalyst. The oxidation was limited at T < 300 degrees C owing to the thermal instability of ozone, but during temperature-programmed oxidation of soot from 25 to 700 degrees C, more than 70% of the carbon was combusted at T < 300 degrees C. The O-3-induced soot oxidation rate over LaMnO3 at 150 degrees C was comparable to the NO2 (and O-2)-induced soot oxidation rates over LaMnO3 at 430 degrees C and Pt/gamma-Al2O3 at 410 degrees C. The K-substitution degree (x) of La1-xKxMnO3 had little influence on the catalytic activity in ozone-induced soot oxidation, which is a reflection of the similarity of the substituted catalysts in the number of surface oxygen vacancies.

Automated summary

This study found that the oxidation of soot induced by ozone was greatly enhanced by using La1-xKxMnO3 as a catalyst in the temperature range of 100-150 degrees C. The degree of K-substitution had little influence on the catalytic activity of ozone-induced soot oxidation.