Catalytic hydro-dealkylation of 2-methylnaphthalene with catalysts loaded W/La for conversion to naphthalene
The naphthalene derivatives in coal tar naphthalene and anthracene oil fractions mostly contain short-chain alkyl groups. The enrichment of PAHs (polycyclic aromatic hydrocarbons, mainly including naphthalene, anthracene, and pyrene) by the dealkylation of PAHs-rich fraction in coal tar was assumed to obtain high-purity PAHs by distillation. Based on this strategy, using 2-methylnaphthalene as the model compound, and the influences of catalysts with different supports (SiO 2 , Al 2 O 3 , ZSM-5, Beta, and HY) and different active metal components (Ni, Co, Mo, and W) prepared by the equivalent-volume impregnation method on the hydro-dealkylation performance of 2-methylnaphthalene under different technological conditions (temperature, H 2 initial pressure and reaction time) were systematically investigated in a pressurized batch reactor. The experimental results show that the conversion rate of 2-methylnaphthalene is 81.23 % and the selectivity of naphthalene is 64.22 % under conditions of 480 °C, 2 MPa, 4 h, and 6 W-HY. Loading 0.8 wt% La on the 6 W-HY catalyst can improve the dispersion of active metal component W on the support, but it does not change the skeleton structure of the support. In addition, one-dimensional diffusion is the most probable reaction mechanism for 2-methylnaphthalene, and the evolution profiles of naphthalene can be reflected by the reaction mechanism with a reaction order of n = 4 using the model fitting method.
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