The front-end acetylene converter is located upstream of the cold box prior to the separation of hydrogen from the olefins. In addition to acetylene and ethylene, the feed contains various amounts of hydrogen, carbon monoxide and heavier hydrocarbons, depending on the distillation configuration. PRICAT™ PD 308 series catalysts are formulated to ensure complete acetylene removal whilst avoiding significant ethylene hydrogenation. All versions of PRICAT PD 308 are designed to reduce the acetylene concentration to less than 1 ppm.
The tail-end acetylene converter is located downstream of the cold box and de-ethaniser. The feed contains acetylene, ethylene, ethane and only a trace of lighter and heavier compounds. A controlled amount of hydrogen is added to effect the selective hydrogenation of acetylene. PRICAT PD 408 series catalysts are formulated to ensure complete acetylene removal whilst avoiding significant ethylene hydrogenation and minimising green oil formation.