Impact of iron deposition on Pd/delta-Al2O3 in selective hydrogenation of pyrolysis gasoline

In selective hydrogenation of pyrolysis gasoline, Pd/Al2O3 is often deposit ed with iron species due to corrosion of equipment. The impact of deposited iron on the Pd/Al2O3 is examined. TPR (temperature-programmed reduction) r esults suggest that the clusters of deposited iron remain segregated from P d clusters. By use of a model of Fe2O3-Pd/Al2O3 in hydrogenation of pyrolys is gasoline, the deposited iron is shown to increase isoprene conversion, o lefin selectivity, and coke formation. TPD (temperature-programmed desorpti on) of NH3 and TPR results indicate that the deposited iron is in the form Fe2O3, which increases the acidity of the catalyst. The increased acidity p romotes coke formation. Excess coke formation leads to high-pressure drops and eventually bed plugging.