HZSM-5 Zeolite As Catalyst Additive for Residue Cracking under FCC Conditions

A study has been carried out on the use of hybrid catalysts (physical mixture of a commercial catalyst for residue cracking with others prepared based on HZSM-5 zeolites) in the cracking of a mixture made up of atmospheric distillation residue with vacuum gas oil (VGO), with the latter being the standard feed in FCC (fluidized catalytic cracking) units. The cracking has been carried out in the 525−575 °C range, using catalysts subjected to a severe steaming treatment in a riser simulator operating at laboratory scale under similar conditions to those of a FCC reactor. The results show the relevant role of HZSM-5 zeolite on product distribution. Significant findings are the lower overcracking of LPG and gasoline fractions and the lower coke yield, which are due to the attenuation of the reactions attributable to the acid matrix of the base catalyst. The addition of HZSM-5 zeolite is also efficient for increasing the content of C 3 and C 4 olefins in the LPG and C 5 and C 6 olefins (especially i-olefins) in the gasoline and for decreasing the content of C 6 −C 8 aromatics.