Preparation Of Unsupported NiMoW Sulfide Nanocatalysts And Their Hydrodeoxygenation Performance

In this thesis, a series of unsupported NiMoW nanocatalysts were successfully prepared, and they were characterized by means of XRD, XPS, SEM, TEM and BET specific surface area measurements. The HDO performance was also tested by using4-methylphenol as a model conpound.The unsupported NiMoW nanocstalysts were successfully prepared by a novel mechanical activation method followed by the annealing, in which MoO3, WO3, Ni(NO3)2·6H2O and abount S as the reactants. And the influence of promoter and annealing tempreature on the structures and catalytic functions were also disscussed. The results showed that the catalysts had a nanosheets structure and the moderate surface areas. The addition of Ni significantly increased the HDO activity and the activity increased to the maximum at Ni0.33MoW (k4-MP=2.16×10-5mol-1gcat-1), then decreased with increasing nickel content. Furthermore, the addition of Ni promoted the DDO pathway. The annealing tempreature promoted the crystal growth of the nonocatalysts and the surface area decreased with the increasing of annealing tempreature. NiMoW at600℃possessed the highest catalytic activity (k4-MP=1.22×10-5mols-1gcat-1).The increasing of annealing tempreature promoted the DDO pathway.By comparing the unsupported NiMoW, NiMo and NiW catalysts, the influence of the active components on the structure and HDO performance was investigated systematically. The results showed that tungsten played an active effect on the catalysts textural properties since higher surface areas were obtained. Due to the increase of surface area and the percentage of NiMo(W)S active phase, the activity was greatly enhanced. NiMo3W2showed the highest activity with97.8%4-MP conversion and the reaction rate constant was2.2×0-5mols-1gcat-1。 The addition of tungsten promoted the DDO pathway and the DDO selectivity of the catalysts increased with the increased stack height in accordance with the Rim-Edge model. When it refered to the comparison between NiMoW and NiW, the addition of molybdenum reduced the stack degree along the c direction. The surface area changed greatly from8.26m2·g-1to32.24m·g-1, since the increasing of surface area guaranted the increasing of active sites, resulting in the enhancement of HDO activity. The HDO activity was decreased in the order of NiW3Mo3>NiW3Mo2>NiW3Mo4>NiW3Mo>NiW3. In addition, the catalysts preferred the reaction route of direct-deoxygenation (DDO) but promoted the HYD pathway during the reaction of5h in the HDO of4-methylphenol. Furthermore, the relationship between product selectivity and stack height was in accordance with the Rim-Edge model. In this paper, there are28figures,11tables and94references.