Effect of Iron Compound Accumulation on Apparent Bulk Density and Catalyst Activity of FCC Catalyst

The influence of iron compounds accumulation on FCC catalyst has been reported in viewpoint of drop of apparent bulk density and deterioration of cracking activity. In this paper, these iron issues were investigated by using equilibrium catalyst. Accumulation of iron compounds on catalyst led to nodule formation to decrease ABD of equilibrium catalyst. However, in some cases, lowering of ABD was observed even in little nodule formation. The magnetic susceptibility of the catalysts increased with iron oxide content. This suggests the lowering of ABD is mainly due to magnetic repulsion between catalyst particles. From selected area electron diffraction analysis, iron compounds were found to be composed of Fe3O4, Fe2O3 and NiFe2O4, and then magnetism of the catalyst might come from formation of Fe3O4. Peeling of the iron compounds deposited on the surface of catalyst particles resulted in recovering the FCC performance of equilibrium catalyst. From these results, it was suggested that iron compounds deposited on mainly catalyst surface plugged pores to disturb diffusion of feed oil and led to lower FCC performance.