Catalytic Cracking of Arab Super Light Crude Oil to Light Olefins: An Experimental and Kinetic Study

Catalytic cracking of Arab Super Light (ASL) crude oil (containing 46.1 wt naphtha-range fraction) was studied over zeolite Y- (Y-Cat) and MFI-based (Z-Cat) catalysts at 500-575 degrees C. Experiments were conducted in a riser simulator by varying the residence times from 1 to 10 s. ASL crude oil and the cracked products were divided into heavy fraction, naphtha, and C-1-C-4 gases. Experimental results showed that additional naphtha is formed due to the cracking of the heavy fraction, and the formation of C-1-C-4 gaseous products occur mostly via cracking of naphtha. An increase in reaction time or temperature showed a more pronounced effect on the propylene yield compared to that of ethylene. Z-Cat produced more ethylene and propylene, which was attributed to its higher acidity, shape selectivity, and the higher hydrogen transfer reaction over Y-Cat. A three-lump model was appropriate for kinetic modeling of the catalytic cracking of ASL over Y-Cat. Comparison of the activation energies and rate constants showed that conversion of the heavy fraction to naphtha (E-HN = 9.89 kcal/mol) was easier compared to the cracking of naphtha to C-1-C-4 gaseous products (E-NG = 15.79 kcal/mol). Direct cracking of heavy fraction to C-1-C-4 gaseous products was found to have highest activation energy (E-HG = 79.89 kcal/mol) in the reaction scheme.