MTO REACTION OVER SAPO-34 CATALYSTS SYNTHESIZED BY DIFFERENT CRYSTALIZATION TEMPERATURES

Silicoaluminophosphate, SAPO-34, is known as promising molecular sieve, which is widely used in catalysis, separation processes, and are being developed for new applications, especially in the methanol-to-olefin (MTO) process. In order to investigate the effect of different crystallization temperatures on the crystallinity, morphology and particle size of SAPO-34, SAPO-34 catalysts were successfully synthesized using the conventional hydrothermal method. The prepared samples werecharacterized by XRD, SEM and FTIR techniques. The catalytic performance of the synthesizedcatalysts was tested in MTO reaction at 410˚C and WHSV of 6.5 h-1. The results showed that formation of SAPO-5 and SAPO-11 impurities is enhanced by increasing the crystallizationtemperature from 463 K up to 483 K. Temperature of crystallization were found out as the significant parameter for controlling crystallinity and purity, particle size, morphology and content of hydroxyl groups of the product. The sample prepared at 463 K and 24h possessed the best crystallinity with the smallest crystal size. In the methanol conversion to olefins over SAPO-34 catalysts, this sample showed highest yield of light olefins (90% wt).

Keywords:

SAPO-34 , Crystallinity , Synthesis temperature , MTO reaction