The Synthesis Of Nano-hierarchical Pore MOR Zeolites And Its Application In The Conversion Of Heavy Aromatic Hydrocabons

Compared with the conventional mordenite zeolites,the nano-hierarchical pore MOR zeolites that combined the characteristics of nano materials and hierarchical pore materials will be more widely used in the catalysis and other fields. In this dissertation, Nano-MOR zeolites were firstly synthesized via hydrothermal crystallization method, and then the nano-hierarchical pore MOR zeolites were successfully prepared by two-step and one-step methods respectively. The effects of synthesis conditions on the particle size and pore structure of the MOR zeolites were examined. Pt/MOR zeolite catalysts were prepared by incipient impregnation method, and the effects of pore forming on the hydrodealkylation performance of Pt/MOR zeolite catalysts were investigated.The results of nano-MOR zeolite preparation by hydrothermal crystallization method showed that the suitable conditions for preparing nano-MOR zeolite were as follows,crystallization temperature 130 ?, crystallization time 48 h, H2O/Si 18:1, NaOH/Si 0.36 and rotating speed 20r/min, Under the conditions above, the particle size of MOR zeolite obtained was about 30.0 nm.The results of two-step preparation of the nano-hierarchical pore MOR zeolites showed that by direct alkali treatment of nano-MOR zeolites for four hours with NaOH solution of0.2mol/L under temperature 65?, MOR zeolites with nano-scale and micro- and mesoporous structure could be obtained, and the activity of the corresponding catalyst was increased. Firstly, the nano-MOR zeolites was treated for ten hours with 2mol/L nitric acid solution under the temperature 80?, and then was treated with 0.2mol/L NaOH solution for two hours at 65?. The mesoporous volume percentage, mesoporous surface area percentage and the average pore diameter of the MOR zeolites prepared by acid-alkali treatment were increased from 35.5% to 87.7%, 9.4% to 39.0% and from 2.3nm to 2.8nm respectively. The corresponding catalysts showed excellent hydrodealkylation performance.The results of one-step preparation of the nano-hierarchical pore MOR zeolites indicated that CTAB is the suitable pore forming agent. Using CTAB as the pore forming agent, the grain size of the MOR zeolites obtained is about 26.5nm, and the mesoporous volume percentage, mesoporous surface area percentage and the average pore diameter were increased from 35.5% to 62.5%, from 9.4% to 23.3%, and from 2.3 nm to 3.7nm,respectively.The as-prepared MOR zeolites exhibited typical characterizations ofnano-sized and micro-mesoporous structure. Compared with the catalyst supported on nano-MOR, the activity of catalysts supported on the nano-hierarchical pore MOR zeoliteswas significantly improved, and the about inceasing 11% of cumene conversion was obtained under the reaction conditions of reaction temperature 420?, reaction pressure0.8MPa, LHSV 2h-1.