Green Routes For Synthesis Of SAPO-34 Molecular Sieve

The process of methanol to olefins is getting more and more attention,and the core of this reaction is the selecting and preparation of catalysts.Many scholars have found that the molecular sieve of SAPO-34 is the best catalyst and the traditional method for synthesizing it is the hydrothermal synthesis,which needs tetraethylammonium hydroxide as organic template generally,but its price is high,and the yield of the product is low,and tetraethylammonium hydroxide is toxic and harmful,and the residual effluent in the separation not only pollutes the environment but also wastes the raw materials,which is con-trary to the concept of green chemistry.This paper studies the green routes for synthesis of SAPO-34 molecular sieve.The study investigated the synthesis of high crystallinity SAPO-34 molec-ular sieves by mixing two or three inexpensive templates from triethyl-amine,diethylamine and morphine in the absence of tetraethylammonium hydroxide.After establishing the MD-0.3 condition,we studied the synthesis of small-grained molecular sieves in a short period through a two-step temperature changing synthesis.Finally,we investigated the optimal conditions for is the crystallization at low temperature of 100? for 6 hours and the crystallization at high temperature of 200? for 2 hours,which introduces mesoporous,and the smallest and uniform molecular sieve is synthesized under crystallizing for 6 hours.The mother liquor of a single template and mixed template was reused.The full-cycle mother liquor of TEA can be used to synthesize the pure SAPO-34,and the crystallites were small,the yield was as high as 83.36%.The mother liquor of the sample synthesized with the mixed template MOR-DEA can be synthesized.Which has high crystallinity and productivity of up to 88.82%,and its particle size can reach 600 nm.The suspension gel obtained by vortexing the mother liquor of a single template and a mixed template is reused.The pure SAPO-34 molecular sieve with a good crystallinity and an average particle size of about 1?m can be synthesized by using a suspension gel of the mixed tem-plate MD-0.3.When the ratio of the injected colloidal aluminum is 1.5,addi-tional templating agent need not to be added,the pure SAPO-34 molecular sieves with a particle size of 5?m can be synthesized.The pure SAPO-34 mo-lecular sieves with a particle size of 400 nm can be synthesized by a suspension gel of TEA.