Effects of static and stirring aging on physiochemical properties of SAPO-18 and its performance in MTO process

• SAPO-18 was synthesized using static and stirring aging and evaluated in MTO process.
• Aging condition has key impact on the morphology and crystal size of catalyst.
• Stirring aging affected significantly the acid properties and Si incorporation rate.
• The catalyst lifetime in MTO process increased 5 times by using stirring aging.
• Olefin selectivity of 87% with 99% methanol conversion was reached by stirring aging.

This paper was aimed to assess the effects of static and stirred aging on crystal size, morphology, Si incorporation rate, and acidity of SAPO-18 and discusses its performance in methanol-to-olefin (MTO) process. SAPO-18 prepared by static aging had cubic particles with the wide range of 0.05–4 microns but the catalyst synthesized by stirred aging method had uniform crystalline particles with the elongated cubic shape morphology and a narrow distribution size of 100–600 nm. According to the results of FTIR and XRF analysis, the aging procedure can also influence the Si incorporation rate. Agitation during the aging time decreased the Si content in the final catalyst and moderated the acid strength. The catalytic test showed that SAPO-18 sample prepared by stirred aging method was about five times more stable in MTO reaction and had light olefins selectivity of around 87% and methanol conversion of 99%.