Inorganic Ammonia Synthesis Of Zsm-5 Zeolites

ZSM-5 zeolite with high Si/Al ratio , which was a new type of zeolite with a unique pore structure and excellent thermal stability, was developed the Mobil laboratories. Having high catalytic activity and high selectivity of zeolite modified, the zeolite has attracted particular attention from petrochemical industries.The synthesis of a series of ZSM- 5 with high silica to alumina ratio usually need some organic amines such as tetrapropyl amine bromide, ethane diamine, n-propyl amine using as templating agents. The industrial application of the ZSM-5 zeolites had been limited, due to high expensive prices of their raw materials. This work study on the synthesis of ZSM-5 zeolite sieve with some inorganic amine, such as ammonia, and ammonium sulfate, sodium silicate as main materials. The influence of synthetic temperature and crystallizing time on the synthesis of the zeolite are examined. The samples of ZSM-5 zeolites synthesized using ammonia are characterized by the methods of XRD, IR, DSC and isotherm adsorption, comparing with the sample of ZSM-5 zeolite synthesized using n-propyl amine. The catalytic activities of both zeolites on the aromatization of hexane are determined.The experimental results show that the ZSM-5 zeolites synthesized using ammonia have the same structures as those synthesized using n-propyl amine. They have the same absorption band of IR spectra. In addition that there is a shouldered peak about 26 = 23.11 ?.42 of the main peaks in XRD spectra of the latter, which might be caused by the organic impurity in the caves of ZSM-5 zeolites, the other diffraction peaks of both zeolites have the same features. Study of the adsorption of benzene and water on the zeolites indicate that at low temperature there are little lower adsorption volume of water on the ZSM-5 synthesized using ammonia than that en the ZSM-5 synthesized using organic amine, their other features of adsorption are primarily same. The determined results of catalytic activities show that, They possess good activities of hexne-aromatizaton. When Na+ in the zeolites are replaced by ion-exchange method with H+, the more xylene on the zeolites are formed than on the ZSM-5 zeolites containing other metals. This phenomena may be origins from the causes that higher acidity and bigger pores of the zeolite favor the formation of xylene and diffusion. Study on the improvement of ZSM-5 zeolite properties for increasing of selectivity for aromatizition and para-xylene in toluene disproportionate are in progress.