Synthesize ZSM-5 Zeolites With Low Cost

Kaolin as its rich sources and low price,it is acted as materials to synthesized ZSM-5 zeolites.In this paper,firstly,ZSM-5 zeolites was synthesized by steamed assisted cry stallization method in an organic template system.The effect of crystallization time,crystallization temperature,template agent and NaOH/Si was discussed.The results show that the optimalize condition was crystallization temperature 170?,crystallization time 2h,NH3H₂O acted as alkai source with 15 mL.Ratio of raw materials was:n?TPAOH?/n?SiO2?=0.04,n?H₂O?/n?SiO2?=2.08.The synthesized ZSM-5 can be used in the MTA reaction,the selectivity of the BTX and aromatic were 15.6%and 18.1%,the methonal conversion was 74.3%.Then ZSM-5 zeolite have been directly synthesized from kaolin by seeded method.The effects of Kaolin calcination conditions,crystallization condition and Alkali treatment conditions were investigated.The synthesized samples were characterized by means of XRD,FESEM,N2 adsorption-desorption,NH3-TPD and their catalytic performance were evaluated by methanol to aromatic?MTA?reaction.The results showed that when the kaolin was calcined at 800? for 2 h,the crystallization temperature was 200?,crystal seed dosage 3%,molar ratio ofNaOH to SiO2 0.15,cry stallization time 24 h,synthesize ZSM-5 crystallites with higher relative cry stallinity?96%??When using NK seeding,the ZSM-5 zeolites extablish typical hexagonal prism and less than 1 micron diameter,the selectivity of the BTX and aromatic were 29.7%and 31.6%,increased by 1.5 and 0.3 percentage points compared with catalytic activity of parent ZSM-5,respectively.When using SPP seeding,the size of zeolite was only 300-400 nm,the selectivity of the BTX and aromatic were 28.8%and 35.9%Finally,ZSM-5 zeolites was in-situ synthesized on the calcined kaolin microsphere,ZSM-5 with surface area 178 m2/g,pore volume 0.18 cm³/g,micropore volume 0.09 cm³/g were prepared with the following condition:Ethanol and template agent equal volume impregnation,crystallization time 24 h,crystallization temperature 170?.Ratio of raw materials was:TPAOH/Si=0.056,NaOH/SiO2=0.1-0.15.