Mechanism of Catalytic Conversion of Kerosene Co-Refining Heavy Oil to Btexn by Py-Gc/Ms Based on

Kerosene co-refining heavy oil (KCR-H), KCR-H six group components (KCR-HS), six typical model compounds representing the KCR-HS and its mixed model compound were selected as raw materials. The effects of the physicochemical properties of single and bi-metallic modified HZSM-5 (Me/HZSM-5) on the selectivity and yield of benzene (B), toluene (T), ethylbenzene (E), xylene (X), naphthalene (N) in cracking products were investigated by pyrolysis-gas chromatograph/mass spectrometer (Py-GC/MS). The results show that Me/HZSM-5 exhibits superior selectivity for light aromatic in the catalytic conversion of single model compound (MC) and KCR-HS. Compared with polycyclic aromatic hydrocarbons and nitrogen-containing compounds, oxygenated compounds and aliphatic compounds are easier to crack to produce light aromatic hydrocarbons. Using Ni-Mo/HZSM-5 catalytic conversion benzofuran, the selectivity of BTEXN in the cracking product is 65.01%, which is 23.44 times higher than pyrene (2.66%). Due to the preferential cracking of benzofuran, small molecular fragments prepared by tetradecane and methyl naphthalene promote the catalytic conversion of methyl phenol, quinoline, and pyrene. Compared with the theoretical BTEXN yield (1338.39 mg/kg), the experimental BTEXN yield obtained from mixed model compounds (MCs) increasing by 37.95%, which is 1846.40 mg/kg. In addition, the BTEXN selectivity from the catalytic conversion of Saturates over Ni-Mo/HZSM-5 is 62.97%, increases by 12.97% compared with tetradecane, which represents the components of this group, indicating that the synergistic effect between oxygenated compounds and aliphatic compounds is conducive to the dehydrogenation and aromatization of aliphatic compounds to produce light aromatics. Furthermore, the possible catalytic conversion mechanism and pathways of KCR-H and KCR-HS are proposed based on the characterization and catalytic performance of modified HZSM-5. KCR-H forms small molecular free radicals and low-carbon olefins through thermal cracking and catalytic conversion, and generates light aromatic hydrocarbons through hydrogen transfer, aromatization and other reactions.

Keywords: Kerosene co-refining heavy oil, Catalytic conversion, Model compounds, Six group components, Light aromatics