Preparation Of Modified ZSM-5 Zeolite And The Study Of Its Property

With the rapid economic and social development and the increasingly serious environmental situation,the market demand for high quality clean oil greatly improved.Hydrocracking and hydroisomerization are important processing technologies for the production of light oil with inferior heavy distillates,which can effectively improve the quality and yield of middle distillate oil.This paper focuses on the hydroisomerization of n-alkanes to produce high quality gasoline fractions.However,the hydroisomerization process is often accompanied by the occurrence of cracking reaction.Therefore,the isomerization process of low alkane needs to strictly control the reaction temperature,reaction pressure,hydrogen/oil volume ratio and select the appropriate hydroisomerization catalyst.The main purpose of this paper is to develop low-alkane high-performance isomerization catalyst.ZSM-5 molecular sieve has many advantages.The carrier material as hydrogenated isomerism bifunctional catalyst is widely used in the isomerization process of low alkane.Therefore,the ZSM-5 zeolite was optimized and the properties were controlled to meet the production requirements of isomerization of lower alkanes.In this paper,firstly,via hydrothermal crystallization method to synthesize ZSM-5 zeolite,and to modify ZSM-5 zeolite with metal atom Ni applying in situ method and impregnation method respectively,so as to realize the directional control and interaction of acidity,active metal and along with carrier materials.And then use this modified ZSM-5 zeolite as an added components of carrier to complete the final hydrocracking catalyst.The catalyst prepared through in situ method exhibits higher reaction activity,compared with the catalyst prepared through impregnation method.The in-situ modified catalyst conversion rate is lower,but with higher isomeric selectivity.This paper also chooses SAPO-11 zeolite to modify ZSM-5 zeolite to synthesize ZSM-5/SAPO-11 composite zeolite.The ZSM-5/SAPO-11 composite zeolite was prepared by in situ method,and compared with the composite zeolite prepared by mechanical method,and also the single molecular sieve,as the ZSM-5 and SAPO-11 zeolite.The characterizations show that the in situ ZSM-5/SAPO-11 composite zeolite is a composite material which is attached to each other in morphological structure,and has a reasonable distribution of acidity and pore structure.The catalyst of ZSM-5/SAPO-11 composite zeolite was studied in hydrocracking reaction,the result exhibits that the combination effect of ZSM-5/SAPO-11 composite zeolite for hydrocracking could improve the isomerization performance of the catalysts.