The effects of SiO2/Al2O3 and H2O/Al2O3 molar ratios on SAPO-34 catalysts in methanol to olefins (MTO) process using experimental design

• Silicon and water content effects on SAPO-34 synthesis and MTO reaction were studied in this paper.
• High total light olefins selectivity was obtained (71.45%).
• High crystallinity, surface area as well as small crystal size of SAPO-34 catalysts improved the production of light olefins.
• Water content in SAPO-34 synthesis gel had no significant effect on the performance of catalyst in MTO process.
• Catalyst with small crystal size and relatively high crystallinity had the highest light olefins selectivity.

To investigate the effects of silicon and water content on SAPO-34 catalyst, a number of experiments by using response surface methodology of molar ratios of SiO2/Al2O3 = 0.1–0.6 and H2O/Al2O3 = 50–120 were performed. The catalytic performances of prepared SAPO-34 samples at 410 °C and 30 wt.% methanol in water for MTO process were investigated. Due to relatively high crystallinity and small crystal size (1.3 μm); SiO2/Al2O3 = 0.17 and H2O/Al2O3 = 109.75 catalyst showed high total light olefins selectivity (71.45%). ANOVA results indicated that the light olefins selectivity was influenced more by changing of SiO2/Al2O3 molar ratio rather of H2O/Al2O3 molar ratio.

Synthesis and performance of SAPO-34 catalysts with different SiO2/Al2O3 and H2O/Al2O3 molar ratios in MTO process were investigated. Catalyst with molar ratios of SiO2/Al2O3 = 0.17 and H2O/Al2O3 = 109.75 showed the highest value of total light olefins selectivity because of its small crystal size and proper crystallinity.Figure optionsDownload as PowerPoint slide