晶种对合成小晶粒SAPO-34分子筛的影响  

EFFECT OF SEED CRYSTALS ON HYDROTHERMAL SYSTHESIS OF SAPO-34 WITH SMALL PARTICLE SIZE

作　　者：郭智慧 朱伟平 郭磊 Guo Zhihui;Zhu Weiping;Guo Lei(National Institute of Clean and Low Carbon Energy,Beijing 102211)

机构地区：[1]北京低碳清洁能源研究院,北京102211

出　　处：《石油炼制与化工》2022年第9期56-64,共9页Petroleum Processing and Petrochemicals

基　　金：国家能源集团2030重大项目先导项目(GJNY2030XDXM-19-14)。

摘　　要：以较廉价的三乙胺为模板剂,考察晶种的种类、添加环境、添加量及晶粒大小对其辅助合成SAPO-34分子筛的影响,并对晶种诱导机理进行探究。结果表明:含SAPO-5杂晶的晶种会诱导体系产生相同AFI结构的SAPO-5分子筛,但采用磷酸预处理20 h后,可制备出纯净的SAPO-34分子筛;在辅助合成中,晶种硅铝比对合成产品的收率和粒径影响明显,无论添加在酸性还是弱碱性的晶化液中,高投料硅铝比下制备的晶种均更有利于提高产品收率、降低产品平均粒径,其中酸性体系对晶种的部分刻蚀作用可提供更多表面,使晶种的诱导效应更强;在晶种添加量(占晶化液的质量分数)为0~0.5%时,随着高硅铝比晶种添加量的增大,产品收率提高,D(50)降低,且变化尤为明显,当高硅铝比晶种添加量大于1%后,晶种添加量对产品收率和D(50)的影响趋于平缓。此外,晶种辅助合成的小晶粒产品可继续用作晶种起诱导作用,且以之合成产品的收率、平均粒径、元素组成、形貌、孔结构与采用初始大颗粒晶种辅助合成的产品相近,为稳定、连续合成粒径可控的小晶粒分子筛奠定了基础。The effects of seed type,additive environment,additive amount and particle size of seed crystals on hydrothermal synthesis of SAPO-34 molecular sieves and the mechanism of seed were investigated by using triethylamine(TEA)as template.The results showed that SAPO-5 molecular sieves with the same AFI structure crystals could be induced by the seeds containing SAPO-5 heterocrystalline,but the pure SAPO-34 could be prepared by pre-treating the impure seed crystals with phosphoric acid for 20 h.The silicon-aluminum ratio of seed crystal has obvious influence on the yield and particle size of the synthetic product,whether added in the acidic or the weakly alkaline gel.The seeds prepared with high SiO_(2)/Al_(2)O_(3) molar ratio can improve the yield and reduce the average particle size of the product,and the etching effect of acidic system on the seeds can provide bigger surface,so that the seed induction effect is stronger.When the content of crystal seed was 0-0.5%,the yield of product was increased and D(50)was decreased with the increase of the content of seed crystal with high SiO2/Al2O3 ratio.Especially when the content of seed crystal was more than 1%,the effect of seed addition on yield and D(50)of product tended to be gentle.In addition,the small-grain products prepared by seed-assisted synthesis could continue to be used as seed inducers.The yield,average particle size,elemental composition,morphology and pore structure of the product are similar to those of the product prepared with the help of large grain seed,it lays a foundation for the stable and continuous synthesis of small-grain molecular sieves with controllable particle size.

关 键 词：SAPO-34 SAPO-5 晶种 分子筛 小晶粒 

分 类 号：TQ426[化学工程]