Synthesis And Characterization Of Hierarchical ZSM-5 And Y Zeolite

The designing of an efficient catalyst that could effectively mediate the catalytic cracking of heavy oil is of special interest,and efforts have always been devoted to developing novel materials with superior catalytic performances.Among the various catalytic materials,Zeolite ZSM-5 is considered as an important catalyst for heavy oil fluid catalytic cracking(FCC).However,the undesirable microspores in its structure limit its practical applications for long-chain oil molecules.Thus,new strategies are needed to overcome the problems associated with conventional Zeolites.Herein,we prepared hierarchical ZSM-5 with high crystallinity,large surface area,and hydrothermal stability with the added advantage of reducing the diffusion restriction for heavy oil molecules,thereby,facilitating an efficient contact of the long-chain molecules with more active sites,resulting in an improved catalytic conversion of the long chain molecules.Hierarchical zeolite ZSM-5 was synthesized via in-situ crystallization using activated kaolin as raw material.The use of kaolin replaces some chemical reagents and provides active silica and activated alumina required in synthesis process,so that reduce the cost of synthesis.Zeolite ZSM-5 synthesized using kaolin as raw material show high crystallinity,hierarchical pores and hydrothermal stability.The zeolite ZSM-5 was synthesized with hierarchical pores structure from kaolin in the presence of tetrapropylammoniumbromide(TPABr)/MT composite template.The relative crystallinity of the hierarchical zeolite ZSM-5 was 99%.The total surface area was up to 345 m2/g,the external surface area was 154 m2/g,the total pore volume was 0.21 m3/g,the mesopore was 0.18 m3/g and the pore diameter was 3.42 nm.ZSM-5 zeolite was synthesized via in-situ crystallization using kaolin as raw material.The organic template TPABr was used as structure directing agent in the present work.The relative crystallinity of the crystallized sample was 95%,the total surface area was 368 m2/g,the external surface area was 135 m2/g;the total pore volume was 0.2 m3/g,the mesopores volume was 0.17 and the pore diameter was 3.42 nm.Kaolin is used as a raw material for the synthesis of hierarchical zeolite Y.The structure directing agent(SDA)is obtained from a mixture of water glass and(NaAlO2(aq))and this structure directing agent is used for the synthesis of zeolite Y.The zeolite Y sample is crystallized in the heterogeneous reactor at 90? for 18 h.The HY zeolite is obtained by an ion-exchange process.The XRD result shows that zeolite Y synthesized from kaolin have high relative crystallinity of 92%,while the modified HY from zeolite Y have relative crystallinity of 79%.The BET analysis of the zeolite Y shows that the specific surface area was 294.4 m2/g,the external surface was 103.3 m2/g;the total pore volume was 0.2 cm3/g,the mesopore volume was 0.14 cm3/g and the pore diameter was 3.82 nm.