Preparation Of Hierarchical Pores Structure SAPO-34 And Its Application In Mto Reaction

With the increasing depletion of oil resources,methanol to olefin reaction has received wide attention in the past years.The key issue for the MTO reaction is to develop new catalyst for MTO reaction.SAPO-34 molecular sieve due to its unique pore structure and mild acidity,shows high methanol conversion and excellent selectivity to olefin and propene in MTO reaction.Up to now,SAPO-34 molecular sieve is the best catalyst for MTO reaction.However,because of the limitations of its pore channels,coke deposition easily occurs over this catalyst surface and the catalyst life is short during the MTO reaction,which restricts its application in industry.This article is committed to the synthesis of hierarchical pores structure SAPO-34 molecular sieve and investigate its catalytic life in the MTO reaction and the yield of light olefins.In this paper,the synthesis conditions of conventional SAPO-34 molecular sieves were optimized firstly and TEA was chosen as the micropore template for the synthesis of hierarchical pores structure SAPO-34 molecular sieves.And we used soft template method to synthesis hierarchical pores structure SAPO-34 molecular sieves.CTAB,tetradecyl ammounium phosphate and glucose were chosen as the soft templates.With organic ammounium as soft templates,hierarchical pores structure SAPO-34 with high crystallization and mesoporous volume was synthesized by controlling the addition of template and addition order.With glucose as soft template,hierarchical pores structure SAPO-34 with high crystallization and small particle was synthesized by controlling the addition of template and addition order.The MTO reaction results show that,hierarchical pores structure SAPO-34 with CTAB as the soft template has the longest reaction life and lowest selectivity to ethane and propene,hierarchical pores structure SAPO-34 with glucose as soft template has the highest selectivity of ethane and propene and longer reaction life than SAPO-34 synthesized with conventional methods.