Synthesis Of Micro/Mesoporous Zeolites Based On Template Chemistry And Self-Assembly Technique

The residue fluid catalytic cracking process (RFCC) is one of most widely used processes that can handle heavy oils with reasonable recovery of light fractions and acceptable cost, in which RFCC catalysts play a crucial role in guaranteeing good performance. It has been commonly recognized that diffusion control, often defined as accessibility, has become increasingly important for RFCC catalysts because of the short contact time operations. Several methods have been addressed to increasing the accessibility of RFCC catalysts, among which the creation of mesopores and macropores by incorporating mesoporous and macroporous zeolites into the catalyst was considered as an effective approach to improve the accessibility.While microporous zeolites such as Y are playing important roles in modern petrochemical industry for their abundant uniform microporous structures and strong intrinsic acidities, much attention is being paid to the development of a composite formed via self-assembly of precursors of microporous zeolites. The composite zeolites synthesized would have special properties, such as mutually connected microporous-mesoporous pore structure, high hydrothermal stability and graded aciditys. Unfortunately, not all types of zeloite precursors can be synthesized controllably. Naturally, it is reasonable to conceive that the degradation of waste zeolites should provide an economical route to synthesize the precursors of microporous zeolites. Different from the process of direct synthesis of precursors, degradation of waste zeolites have the advantages of reclaiming waste zeolites and thus low cost.In the present investigation, precursors were obtained by degradation of NaY zeolites. Micro/mesoporous GPZ zeolite was synthesized using P123 as the template and Y precursors as the construction units. Systemic characterization results revealed that the mesopore diameter was about 6.7 nm. BET surface area and pore volume were 595.4 m~2/g and 0.75 cm~3/g respectively. In addition, after hydrothermal treatment at 800℃for 4 h, 8 h and 12 h in 100% aqueous vapor, the remain fractions of BET surface were 95 %, 29% and 26% respectively. Micro/mesoporous GMZ zeolite was synthesized using CTMABr as the template and Y precursors as the construction units. Systemic characterization results revealed that the diameter of mesopores was about 3.2 nm. BET surface area and pore volume were 365.6 m~2/g and 0.29 cm~3 /g respectively.In the second part of this investigation, Micro/mesoporous NaY zeolite were synthesized using P123 as the template. Systemic characterization results revealed that the diameter of mesopores was about 3.8 nm. BET surface area and pore volume were 736 m~2/g and 0.37 cm~3/g respectively.In this thesis it has been shown that zeolites with graded pores and high hydrothermal stability were obtained. The successful synthesis of this material throws a light on the industrial application of meoporous zeolites.