Synthesis, Characterization And Application Of Nanoscale Aggregation-resistance Transition Metal Sulfides

Hydrotreating is an effective method of removing sulfur, nitrogen and arene from petroleum products. With the increasingly stringent environmental protection statutes, deep hydrodesulfurization (HDS), hydrodenitrogenation (HDN) and hydrodearomatization (HDAr) is indispensible for petroleum products. Therefore, it is highly demanded to exploit new hydrogenation catalysts with high activities.Resulting from their exclusive composition and configuration, transition metal sulfides nanoparticles have uniquely optical, electronic, magnetic, catalytic and tribological characteristics besides a series of uniquely size-related properties as nanoparticles (small size effect, surface effect, quantum effect, macroscopic quantum tunnel effect). However, they are subjected to agglomeration because of higher surface energy. Our group have made laborious and fruitful research on the synthesis, characterization and application of ultra-dispersed MoS₂ nanometer catalytic materials for many years. In this thesis, an improved synthetic technique was reported. The products'catalytic activities of dispersed and supported catalysts were evaluated. Theoretical and experimental results provided in this thesis are significant for exploring new nanometer hydrogenation catalysts.The main accomplishments are as follows: First, a general facile synthesis method to ultra-dispersed transition metal sulfides nanoparticles was developed. This method is named"Colloid Chemistry Assistant Solvothermal Technique", having advantages such as resources easily available, manipulation convenient, and products high quaility. By adopting this technique, we have got ultra-dispersed composite Co-Mo, Ni-Mo nanoscale sulfides, which were the basis for refining petroleum products. Furthermore, we have also synthesized water-soluble Co, Mo sulfides nanoparticles. The experimental results proved that this method could be extended to synthesize other water-soluble transition metal sulfides nanoparticles. Finally, with as-prepared oil-soluble nanoparticles as precursor, we prepared transition metal sulfides hydrogenation nanocatalysts supported by active carbon using one-step dipping method. The catalytic activities of as-prepared dispersed and loaded hydrogenation nanocatalysts were evaluated by the hydrogenation reaction of naphthalene. The resutls suggested that active carbon supported composite transition metal sulfides nanoscale hydrogenation catalysts were the most active. On the other hand, we have also acquired the optimal atomic ratio of Ni-Mo-S/AC hydrogenation nano-catalysts as Ni/(Ni+Mo)=0.2 or 0.65, and Co/(Co+Mo)=0.2 or 0.5 for CoMoS/AC by the model hydrogenation reactions of naphthalene. And we have primarily probed into the relationship betweeen catalytic activity and catalyst structure. The experiments results revealed that the catalytic activities are related to catalyst composition, granularity, shape, and dispersibility. There is no successive variation pattern between its activity and granularity except a turning point.