The cracking of the waxes obtained in the flash pyrolysis of polypropylene has been studied in laboratory FCC units under the standard conditions in FCC (fluid catalytic cracking) units. The reaction equipment is provided with a riser simulator reactor, and the experiments have been carried out using a commercial equilibrium catalyst, with a catalyst/feed ratio of C/O ) 5.5, in the 500-550 °C range and for contact times between 3 and 12 s. The effect of these operating conditions on the yields of products and on the composition of gas and gasoline lumps has been studied. The results have been compared with those of VGO (vacuum gas oil) cracking, which is the standard FCC feed in refineries, and with those of a mixture of VGO (80 wt %) and waxes (20 wt %).

A study has been carried out on the cracking of a mixture of atmospheric residue (20 wt %) and VGO (vacuum gas-oil) from a refinery, in a riser simulator reactor under industrial unit conditions in the 525-575 °C range, with contact times between 3 and 12 s and using a commercial catalyst for residues. The yields and compositions of the product streams (dry gas, LPG, gasoline, LCO, HCO, and coke) have been compared to those corresponding to a standard feed in a fluidized catalytic cracking (FCC) unit. Catalyst accessibility renders it efficient for maintaining conversion, although overcracking of LCO and gasoline is significant above 550 °C, whereas the cracking of the HCO fraction in the residue is significantly limited. The temperature and contact time (especially the former) have a considerable effect on the gasoline composition, because of the significance of overcracking under process conditions. As the temperature is increased, the olefin concentration increases and that of the other fractions in the gasoline decreases, particularly in the case of C 6 -C 9 aromatics.

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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.