Yunfei Bi

NiWO4 nanoparticles: a promising catalyst for hydrodesulfurization

NiWO(4) nanoparticles have been facilely synthesized by a hydrothermal approach, and used as a catalyst for the hydrodesulfurization of thiophene and its derivative 4,6-dimethyldibenzothiophene, showing a significantly higher activity than commercial NiW/Al(2)O(3).

Relevant parameters for obtaining high-surface area materials by delamination of magadiite, a layered sodium silicate

Layered silicates can be used for the preparation of high surface area materials by intercalation with organic cations followed by ultrasonication. The relevant parameters for delamination (exfoliation) of cetyltrimethylammonium bromide exchange magadiite are investigated. Using a magadiite wet cake, performing the delamination in water and recovering the solid phase by acidification allow increasing the surface area of the final material by a factor of ca. 20 (553 vs. 30 m2 g−1) compared to the standard procedure. The role of each step is analysed and the material resulting from the optimised procedure can be described as creased silicate layers. This results in a microporous–mesoporous material with about 60% of the surface in pores larger than 2.0 nm.

Hydroisomerization of long chain n-paraffins: the role of the acidity of the zeolite

The transformation of n-hexadecane (n-C16) was tested by two series of experiments over bifunctional catalysts with noble metal Pt and a one dimensional ZSM-22 zeolite to investigate the role of the acidity of the zeolite during the hydroisomerization of long chain n-paraffins. In series 1, varying the Si/Al ratio of the zeolite but fixing the zeolite content, reveals that the high acid strength of the zeolite can deteriorate the selectivity of the corresponding catalyst even at an initial conversion and that the low concentration of acid sites on the zeolite is beneficial to the improvement of the maximal value of the isomer yield. In series 2, varying the zeolite content but fixing the Si/Al ratio, reveals that the change of the zeolite content could not affect the selectivity of the catalyst. Both series 1 and series 2 revealed that the activity of the catalyst linearly increases with the acid strength, the concentration of acid sites and the content of the employed zeolite.

Influence of tungsten sources on the synthesis and properties of ammonium dioxothiotungstate

Ammonium dioxothiotungstate was synthesized using different tungsten sources and characterized in detail by powder X-ray diffraction, energy dispersive X-ray spectrometry, transmission electron microscopy, nitrogen adsorption, and temperature-programmed sulfidation. It was found that tungsten oxide nanobelts are superior to ammonium metatungstate as tungsten source for the synthesis of ammonium dioxothiotungstate due to a time-consuming aging step being excluded from the synthesis route. Moreover, detailed characteristic data reveal that, when tungsten oxide nanobelts are used, the physical and chemical properties of the resulting ammonium dioxothiotungstate including particles size, specific surface area, and sulfidation pattern were improved. Also, the hydrodesulfurization measurements showed higher catalytic activity and balanced selectivity of the resulting ammonium dioxothiotungstate.