Study On Catalytic Properties Of SAPO-34 Molecular Sieve Synthetized With Composite Templates

The core technology of coal oil is the MTO process,the key problem of MTO process is high efficient catalyst synthesis.By consulting literature,this paper determines to synthesize SAPO-34 molecular sieve by hydrothermal method.The main research is using different ratios TEAOH/TEA,TEAOH/MOR,TEA/MOR composite templates to synthesize SAPO-34 molecular sieve and the different ratios SiO2/Al₂O₃ effects on composite templates synthsis of SAPO-34 molecular sieve.The SAPO-34 molecular sieves' grain size,structure,acid is studied by XRD,SEM,FT-IR,BET,NH3-TPD characterization methods.Different SiO2/Al₂O₃ ratios of SAPO-34 molecular sieves are synthesized by using composite TEAOH/TEA?2:1?,TEAOH/MOR?2:1?,TEA/MOR?2:1?templates.From MTO reaction results we can see the catalyst life from 120 min to 480 min increases with the reduce of SiO2/Al₂O₃ ratios.Light olefins selectivities increases with the reduce of SiO2/Al₂O₃ ratios,but the difference is little.Light olefins overall selectivity is more than 80% and the hightest is up to 90%.The composite templates synthsis of SAPO-34 molecular sieve has more longer catalyst life than single template.The composite TEAOH/TEA?2:1?,TEAOH/MOR?2:1?,TEA/MOR?1:1?templates synthsis of SAPO-34-0.2 molecular sieve have the longest catalyst life reaching 420 min,480 min,360 min,and light olefins selectivity has reached 86.6%,89.2%,89.5%.By GC-MS analysis the deactived SAPO-34 molecular sieve,the major composition of Carbon deposition are Naphthalene,phenanthrene,pyrene kind of organics.The macromolecular organics jams channel make light olefins cannot spread out in time further into macromolecular organics and the macromolecular organics cover the catalytic acid site,which results in SAPO-34 molecular sieve deactived.