镍前躯体对非负载型Ni-Mo-W柴油加氢催化剂结构和性能的影响

INFLUENCE OF NICKEL PRECURSORS ON STRUCTURE AND ACTIVITY OF UNSUPPORTED Ni-Mo-W CATALYSTS FOR DIESEL HYDROTREATING

以硝酸镍和碱式碳酸镍为Ni前躯体,采用水热合成法制备了一系列Ni-Mo-W复合氧化物,并采用BET,XRD,SEM等手段对合成的复合氧化物进行表征,考察Ni前躯体对Ni-Mo-W复合氧化物结构的影响。采用混捏法制备了非负载型Ni-Mo-W催化剂,在20 mL高压加氢微反装置上以劣质催化裂化柴油为原料考察了非负载型催化剂的加氢性能。结果表明:以硝酸镍为Ni前躯体合成的复合氧化物的比表面积和孔体积较小,Ni-Mo-W复合程度较低,而以碱式碳酸镍为Ni前躯体时则倾向于形成晶相弥散且晶粒尺寸较小的介孔Ni-Mo-W复合氧化物;以大孔体积低比表面积的碱式碳酸镍为Ni前躯体制备的非负载催化剂具有较高的加氢脱硫、加氢脱氮活性,脱硫率高达99.91%,脱氮率高达99.94%。

A series of Ni-Mo-W composite oxides were prepared through hydrothermal synthesis method by changing nickel precursors. The influence of nickel precursors on structure and activity of unsupported catalysts was investigated and the composite oxides were characterized by BET, XRD and SEM. Unsupported catalysts were prepared through wet-mixing-kneading method, and the fluid catalytic cracking （FCC） diesel was used as a feedstock for activity evaluation of the unsupported catalysts in a 20 mL high-pressure hydrotreating unit. The experiment results show that the composite oxides from nickel nitrate have less BET surface area and pore volume. While crystal phase of Ni-Mo-W composite oxide from basic nickel carbonate precursor tends to be amorphous, and particle size is smaller than that from nickel nitrate precursor. The experiments also reveal that surface area and pore volume of the com- posite oxide synthesized by basic nickel carbonate precursor are improved a lot. The activity evaluation results show that the catalyst prepared hy basic nickel carbonate with larger pore volume and lower sur- face area performs the highest activity of hydrodesulfurization （HDS）, hydrodenitrogeneration （HDN） and aromatics saturation. The sulfur and nitrogen removal rate reaches to 99.91% and 99.94%, respec- tively.