Preparation Of Hierarchical Pore/small Size SAPO-34 And Its Catalytic Performance Of Methanol To Olefins

Methanol to olefin reaction（MTO）is considered to be the most effective non-petrochemical route for the production of low carbon olefin.SAPO-34 stands out among the many catalysts that can be used in MTO reaction,which is due to its unique pore structure,shape selectivity and suitable acidity.However,it also has the disadvantage that carbon deposition leads to catalyst inactivation.Therefore,the modification of SAPO-34 has become a hot and difficult research subject.This paper will modify the traditional SAPO-34 from two aspects:small sized and hierarchical SAPO-34.（1）Small seized SAPO-34 was successfully synthesized by used surfactant Pluronic F127 as growth inhibition.The synthesized SAPO-34 was studied by means of XRD,SEM,NH₃-TPD,and ²⁹Si,²⁷Al,MAS NMR test.The results show that the introduction of Pluronic F127 can effectively reduce the crystal size,increase the external surface area adjust the acidity and improved MTO lifetime.At the same time,Pluronic F127 was put into the SAPO-34 system synthesized by different templates,and the smalle size SAPO-34 molecular sieve was also obtained,which proved the effectiveness of Pluronic F127 to reduce the crystal size.（2）Hierarchical SAPO-34 was successfully synthesized by pseudoboehmite/silica,aluminum isopropanol/TEOS as Al source and Si source respectily,triethylamine as structure-directing agent and nanometer CaCO₃ as mesoporous template.Then XRD,SEM and NH₃-TPD tests were carried out.The result confirmed that the better crystallinity of SAPO-34 with hierarchical structure was obtained.And the MTO reaction show that the hierarchical SAPO-34 exhibited better catalytic activity than the conventional SAPO-34.In addition,the addition of CaCO₃ can still form hierarchical structure in the SAPO-34 system synthesized by different Al source and Si source.This paper provides a green,economical and convenient method for the synthesis of SAPO-34 catalyst with good MTO catalytic performance,and is expected to be used in the preparation of other high performance molecular sieves.