Methanol-to-olefins catalysis on ERI-type molecular sieves: towards enhancing ethylene selectivity

• ERI-type molecular sieves enhance ethylene selectivity in MTO . Acidity significantly influences ethylene-to-propylene ratio materials. Changes acidity alter hydrocarbon-pool species concentration and composition. Low acid site densities hinder the formation of aromatics (thus, ethylene) ERI. (SSZ-98, UZM-12, zeolite, SAPO-17) are synthesized with varying Si/Al = 5–9 Si/T-atoms 0.034–0.12 using several organic structure-directing agents (OSDAs), evaluated as catalysts for methanol-to-olefins (MTO) reaction. SAPO-34 (Si/T-atoms 0.089) SSZ-13 (Si/Al 15) also prepared tested comparison. The zeolites gave improved ratios (E/P 1.1–1.9) over 0.82) 0.85). SAPO-17 samples produced an E/P 0.7–1.1 a generally high C 4 + fraction. differences observed olefins product distributions between low framework > 1.5) Si/T-atom < 0.1 ? 1 +) result slower maturation aromatic (HP) presence bulky alkyl-groups (C 3 -C ) samples. rapid cyclic intermediates shift their composition towards less-methylated ((CH n?4 methylbenzenes methylnaphthalenes found to be key enhancing sieves.