Catalytic Treatment of Vacuum Carburizing Off Gas

The aim of this investigation was to find a suitable procedure for the treatment of higher polycyclic aromatic hydrocarbons, produced during vacuum carburizing of steel. In a lab scale apparatus the carburizing gas acetylene was pyrolyzed and the generated gases converted in a downstream catalytic bed reactor. The results show that it is possible to remove the higher pyrolysis products from the off gas. A complete conversion of the off gases into carbon and hydrogen was achieved with a Ni/SiO2/SiC-catalyst at temperatures ≫ 520 °C. Coke, formed during the conversion of the hydrocarbons on the catalyst, is removed from the catalyst by burning it off. The functionality of the catalyst is investigated for both the reduced and the non-reduced state, whereby the non-reduced catalyst deactivates faster.