不同硅铝比SAPO-18分子筛的合成及其MTO性能

Synthesis and MTO performance of SAPO-18 molecular sieves with different Si/Al ratio

关键词:  SAPO-18  合成  MTO  催化  性能 

Key words:  SAPO-18  synthesis  MTO  catalytic  performance

摘要:

以N,N-二异丙基乙胺为模板剂,通过水热法合成了SAPO-18分子筛。借助XRD、SEM、BET、FTIR对分子筛进行表征后发现,当硅铝比(物质的量比)介于0.2～0.6时能成功合成出SAPO-18分子筛；对分子筛进行MTO评价发现,当硅铝比较低时,分子筛的寿命较长,但是选择性偏低；随着硅铝比的提高,分子筛的寿命降低,其选择性略微提高。综合考虑硅铝比为0.2的SAPO-18分子筛最适宜,其双烯选择性为76%,寿命为140 min。此外,还探究了反应温度和空速对于SAPO-18分子筛催化MTO过程的影响,发现适当增大温度和空速都能提高SAPO-18分子筛的双烯选择性。 

Abstract:

SAPO-18 was hydrothermally synthesized using a template of N,N-diisopropylethylamine(DIEA). The molecular sieve was characterized by XRD, SEM, BET and FTIR. The results showed that the SAPO-18 molecular sieves could be successfully synthesized when the silica-alumina ratio (molar ratio) was between 0.2 and 0.6. The molecular sieve was evaluated in MTO process. It was found that when the silica-alumina ratio was low, the life of the molecular sieve was long, but the selectivity was low. With the Si/Al ratio increased, the life of zeolite decreased and the selectivity increased slightly. To be considered comprehensively, the SiO₂/Al₂O₃ ratio of 0.2 was the most suitable, its dilute selectivity was 76% and the lifetime was 140 min. In addition, the effects of reaction temperature and space velocity on SAPO-18 zeolites catalyzed MTO process were also investigated. It was found that the double dilute selectivity of SAPO-18 zeolites could be increased with the increase of temperature and space velocity.