Catalysts for Demetallation of Low-Temperature Coal Tar

A variety of catalysts were prepared to investigate the effects of active metals and phosphorous on hydrodemetallation (HDM) and hydrodesulfurization (HDS) of a typical medium-temperature coal tar from Xinjiang in China. A dispersant is used to improve the dispersion of active components on the surface of the support compared with the catalysts without dispersant. The hydrodemetallation products of the autoclave under mild conditions were characterized by inductive coupled plasma emission spectrometer (ICP) and microcoulometer. The difficulty of metal removal is as follows: Mg>Na>Al>Ca>Fe. The combination of H ₃ PO ₄ ,(NH ₄ ) ₆ Mo ₇ O ₂₄ ·4H ₂ O, and Ni(NO ₃ ) ₂ ·6H ₂ O precursors generated more type II "Ni-Mo-S" active phases, with the highest catalytic activity. The dispersant polyvinyl pyrrolidone (PVP) was beneficial for the dispersion of metals, forming highly dispersed active centers, thereby increasing the activity of the catalyst. The hydrogenation desulfurization and hydrogenation demetallation occur at the same active site. The catalyst showed good stability within 168 hours.