Pathways of Conversion of Middle Distillate Hydrocarbons in Deep Catalytic Cracking to Produce Light Olefins

The relevance of cracking diesel fractions into light olefins is determined by the strategic need to transition from a fuel-based refinery model to a petrochemical-based refinery model, growing global demand for polymers, and environmental sustainability requirements. The aim of this work is to explore the possibility of the selective production of light olefins from diesel fraction hydrocarbons. The pathways of high-temperature catalytic cracking of individual hydrocarbons that simulate the composition of diesel fractions over catalysts containing zeolites of various types (Y, ZSM-5, and β) have been studied. Maximum selectivity for light olefins in the cracking of aliphatic and alkylaromatic hydrocarbons was achieved using catalysts with the lowest activity in hydrogen transfer reactions. Based on the cracking of tetraline, it was shown that at temperatures above 625 °C, the kinetic control of the reactions under deep cracking conditions is predominant, whereas at lower temperatures, the selectivity is controlled by thermodynamics. Light olefin selectivity in the case of substituted aromatic and naphthenic hydrocarbons strongly depends on the porous structure of the catalyst. Conversion pathways for different classes of hydrocarbons under deep catalytic cracking conditions are proposed.