WP/γ-Al2O3催化剂的制备、表征及加氢脱硫和加氢脱氮活性

Two series of WP/Al2O3 catalyst precursors with WP mass loading in the range 18.5%-37.1% were prepared using the impregnation method and mixing method, respectively, and the catalysts were then obtained by temperature-programmed reduction of supported tungsten phosphate (precursor of WP/Al2O3 catatlysts) in H2 at 650℃ for 4h. The catalysts were characterized by XRD, BET, TG/DTA, XPS and 31p MAS-NMR. The activities of these catalysts were tested in the hydrodenitrogenation (HDN) of pyridine and hydrodesulfurization (HDS) of thiophene at 340℃ and 3.0MPa. The results showed that owing to the stronger interaction of the support with the active species, the precursor of WP/Al2O3 catalyst was more difficultly phosphided and a greater amount of W species was in a high valence state W6 on the surface of the catalyst prepared by the impregnation method than that by the mixing method. 31p MAS-NMR results indicated that 31p shift from 85% H3PO4 of 2.55 × 10-4 for WP and 2.57 × 10-4 for WP/γ-Al2O3 catalysts prepared by mixing method. Such WP/Al2O3 catalysts showed higher HDN activities and lower HDS activities than those prepared by the impregnation method under the same loading of WP.WP/γ-Al2O3 catalysts with weak interaction between support and active species were favorable for HDN reaction while the WP/γ-Al2O3 catalysts with strong interaction were favorable for HDS reaction.

Preparation, Characterization, Hydrodesulfurization and Hydrodenitrogenation Activities of Alumina-supported Tungsten Phosphide Catalysts

Two series of WP/Al₂O₃ catalyst precursors with WP mass loading in the range 18.5%–37.1% were prepared using the impregnation method and mixing method, respectively, and the catalysts were then obtained by temperature-programmed reduction of supported tungsten phosphate (precursor of WP/Al₂O₃ catatlysts) in H₂ at 650°C for 4h. The catalysts were characterized by XRD, BET, TG/DTA, XPS and ³¹P MAS-NMR. The activities of these catalysts were tested in the hydrodenitrogenation (HDN) of pyridine and hydrodesulfurization (HDS) of thiophene at 340°C and 3.0MPa. The results showed that owing to the stronger interaction of the support with the active species, the precursor of WP/Al2O₃ catalyst was more difficultly phosphided and a greater amount of W species was in a high valence state W⁶⁺ on the surface of the catalyst prepared by the impregnation method than that by the mixing method. ³¹P MAS-NMR results indicated that ³¹P shift from 85% H₃PO₄ of 2.55 × 10⁻⁴ for WP and 2.57 × 10⁻⁴ for WP/γ-Al₂O₃ catalysts prepared by mixing method. Such WP/Al₂O₃ catalysts showed higher HDN activities and lower HDS activities than those prepared by the impregnation method under the same loading of WP. WP/γ-Al₂O₃ catalysts with weak interaction between support and active species were favorable for HDN reaction while the WP/γ-Al₂O₃ catalysts with strong interaction were favorable for HDS reaction.