Study on acid-base coupled catalytic pyrolysis of heavy crude oil to light olefins and aromatics by Py-GC/MS and fixed bed reactor

Direct catalytic cracking of heavy crude oil has gained attention as an alternative and cheapest method of producing raw materials for the petrochemical industry. The Py-GC/MS technique was used to study the effects of calcium aluminate base catalysts and ZSM-5 acid zeolites on heavy crude oil conversion. The results showed that ZSM-5 with a Si/Al ratio of 40 (40Z) outperformed zeolites with Si/Al ratios of 80 and 200, with a maximum selectivity of 65% for light olefins and BTX (benzene, toluene and xylene). Among all base catalysts studied, calcium aluminate (CaAl-3) had the highest selectivity of 23% of C2-C4 olefins and BTX. The Mix model outperformed the Base + Acid or Acid + Base models in terms of minimizing hydrogen transfer reactions and maximizing the yield and selectivity of light olefins. The 30 C catalyst (30%CaAl-3 +70%40Z) exhibited sig-nificant co-effect of basic and acidic catalysis, with maximum light olefin selectivity and total olefinicity of 72% and 81%, respectively. The results of the present work showed that acid-base coupled catalytic pyrolysis was a viable approach for improving the yield of light olefins and aromatics.

Automated summary

Direct catalytic cracking of heavy crude oil is a cost-effective method for producing raw materials for the petrochemical industry. This study investigated the effects of calcium aluminate base catalysts and ZSM-5 acid zeolites on heavy crude oil conversion using the Py-GC/MS technique. The results showed that ZSM-5 with a Si/Al ratio of 40 had the highest selectivity for light olefins and BTX, while calcium aluminate (CaAl-3) had the highest selectivity for C2-C4 olefins and BTX. The Mix model of acid-base coupled catalytic pyrolysis demonstrated the best performance in terms of hydrogen transfer reactions and yield of light olefins.