Study On The Synthesis Of SAPO Molecular Sieve With Liquid-phase Crystallization Method

The research meaning of SAPO-34 molecular sieve and methanol-to-Olefins at home and abroad were reviewed.The synthetic method and the effect to SAPO-34 molecular sieve of the purity of raw materials were studied in this article.A series of SAPO-34 molecular sieve samples and SAPO-20 molecular sieve samples were synthesized with a new method that named liquid-phase crystallization method.SAPO-34 and SAPO-20 molecular sieve samples have been characterized by specific surface area,XRD,SEM and FT-IR techniques.Crystallization temperature,crystallization time and the purity of alumina,silica sol and template have important effect to the crystallization of SAPO-34 molecular sieve.140-180℃and 96-120h were suitable crystallization temperature and crystallization time of SAPO-34 molecular sieve synthesized with liquid-phase crystallization method.The purity of silica sol was the seriousest effect to the crystallization of SAPO-34 molecular sieve.The effect to SAPO-20 molecular sieve of the size of dry gel granule,the time of adding template and HF were studied.The result showed the small size dry gel granule was advantageous to the crystallization of SAPO-20 molecular sieve.Add some template to dry gel when making it,have little effect to SAPO-20 molecular sieve.HF would improved the crystallization of SAPO-20 molecular sieve.The raw materials composition were same,only the quantity of template was changed,different molecular sieve were synthesized.SAPO-20 molecular sieve samples have been synthesized by using Morpholine as template,while SAPO-34 molecular sieve samples have been synthesized by using Morpholine and tetraethylammonium hydroxide (TEAOH) as template.The SAPO-34 molecular samples synthesized with different purity sources with liquid-phase crystallization method were investigated by MTO process.The resulte showed at 320℃,the conversion of CH₃OH exceeded 95%,the overall selection of ethylene and propylene is more than 78%.