NiAlZrW hydrodesulfurization catalysts derived from tungstate intercalated NiAlZr layered double hydroxides

A series of tungstate-intercalated NiAIZr layered double hydroxides (LDHs) with different Zr contents were prepared by an ion exchange method. The LDHs were further calcined at 450 degrees C to obtain NiAIZrW mixed metal oxides as hydrodesulfurization (HDS) catalysts. The properties of the LDHs and catalysts were characterized and their activity was evaluated by the HDS of dibenzothiophene (DBT). The results show that W7O116- anions are successfully intercalated in the interlayer gallery. Upon calcination, tungsten species are highly dispersed on the catalysts even at the tungsten oxide content above 50 wt%, owing to the peculiar layered structure of LDHs. On the LDHs-derived catalysts, amorphous and dispersed NiWO4 species are formed due to the reaction between Ni in the layer and tungstate in the interlayer during calcination. The introduction of Zr could further facilitate the formation of highly dispersed NiWO4 species and improve their reducibility by weakening the strong W-O-Al interaction. This is responsible for the superior HDS activity and higher hydrogenation selectivity of Zr-containing catalysts derived from LDHs, in comparison with those of Zr-free catalysts and the catalyst with the same metal contents prepared by the impregnation method. The present work may offer a convenient approach to prepare active HDS catalysts by provoking the formation of NiWO4 species with both high dispersion and reducibility. (C) 2017 Elsevier B.V. All rights reserved.