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 C 2 -C 4 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 significant 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. • Acid-base coupled catalytic pyrolysis process was proposed. • ZSM-5 (SiAl = 40) and CaAl-3 showed maximum light olefins and aromatics selectivity. • The "Mix model" exhibited significant co-effect of basic and acidic catalysis. • Highest light olefins yield and total olefinicity was obtained over 30%CaAl-3/70%40ZSM-5. [ABSTRACT FROM AUTHOR]