The general procedure for the synthesis of the target compounds (CAS: 3877-19-8) and 6-methyl-1,2,3,4-tetrahydronaphthalene from 2-methylnaphthalene is as follows: first, n-hexadecane solution of the model feedstock is prepared, where the substrate concentration is 10% (the substrate consists of unsubstituted bicyclic aromatic naphthalene, 1-methylnaphthalene, 2-methylnaphthalene, 1,5-dimethylnaphthalene and 2,3-dimethylnaphthalene). The substrate and a calculated amount of precursor compound were accurately weighed and added to the insert tube, adding the oxide or its precursor (e.g., zirconium oxide) if necessary. Subsequently, the insert tube was placed in a 20 mL steel autoclave. The reaction conditions were set at temperatures ranging from 380°C to 400°C, hydrogen pressures ranging from 2 MPa to 5 MPa, and strong stirring was maintained. The molar ratios were set as follows: substrate/Mo 18.4:1 and 36.8:1, substrate/W 18.4:1, substrate/Ti 2.4:1, 4.9:1, 7.3:1, 9.7:1, and 12.5:1, substrate/Al 4.9:1 and 9.7:1, substrate/Zr 70.2:1, and substrate/Co 37.2:1. Catalysts were prepared by in-situ sulfidation in hydrocarbon feedstock prepared by in situ sulfurization in hydrocarbon feedstock with the addition of elemental sulfur (dissolved in n-hexadecane) in an amount of 2.5 wt% by weight of the feedstock. The autoclave was heated to the experimental temperature at a rate of 10°C/min. Upon completion of the reaction, the autoclave was cooled to room temperature and the catalyst was separated from the conversion product by centrifugation. Non-uniformity of the gaseous products of feedstock conversion was observed during the experiment.
