Synthesis, Characterization And Catalytic Hydrogenation Performances Of Mesoporous ZSM-5 Zeolites

In this paper, mesoporous ZSM-5 zeolites was synthesized in air of water steam using nano-carbon particles as the"hard template". Ni-Mo catalyst with mixture ofγ-Al2O3 and mesoporous zeolite as support was prepared and the catalytic performance in HDS and HDN was evaluated.The optimal synthesis condition was obtained, after the influence of carbon particles mass, ethanol mass, crystallizing time and calcining temperature on the performances of the mesoporous ZSM-5 zeolites was investigated. The mesoporous zeolites were characterized by XRD, BET, Py-IR, SEM, TEM, EDAX and AAS, and the results showed that the pore size distribution, pore volume and mesoporous wall thickness of the mesoporous zeolites could be controlled by using different carbon particles and changing the mass of the carbon particles. The mesoporous zeolites with smaller pore volume exhibited higher crystallinity, stronger acidity, higher thermal and hydrothermal stability.In this paper, the carriers and catalysts were characterized by XRD, BET, Py-IR, NH3-TPD and HRTEM. Compared with Ni-Mo/γ-Al₂O₃, catalysts containing mesoporous zeolites showed lager pore volumes, lager pore diameter and more Bronsted acid, the number of single MoS₂ layer decreased and the average number of MoS₂ layers increased.The evaluation of HDS and HDN catalytic activity was carried out in a high pressure micro-reactor, DBT and quinoline was used as model molecule respectively. Compared with Ni-Mo/γ-Al2O3, the catalysts containing mesoporous zeolites exhibited stronger acidity, and higher desulfurization and denitrogenation activity through the direct hydrogenalysis route. Meanwhile, the reaction between active constituent and carrier was reduced because the existence of mesoporous zeolites in carrier, and the number of MoS₂ layers increased, thus enhanced the forming of more catalytical active sites and the improving of hydrogenation ability. Compared with microporous zeolites-containing catalyst, catalysts containing mesoporous zeolites had lager pore volume and pore size, which reduced the diffusion resistance of large molecules and avoided the happening of side reactions.