Methanol to olefins: activity and stability of nanosized SAPO-34 molecular sieves and control of selectivity by silicon distribution

• Published in: Physical chemistry chemical physics : PCCP Vol. 15; no. 35; pp. 14670 - 14680
• Main Authors: ZHIBIN LI, MARTINEZ-TRIGUERO, Joaquín, CONCEPCION, Patricia, JIHONG YU, CORMA, Avelino
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 21.09.2013
• Subjects: Chemistry; Coke; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Methyl alcohol; Molecular sieves; Nanomaterials; Nanostructure; Olefins; Porous materials; Selectivity; Silicon; Deactivation; Stability; Hydrocarbon; Coke; Crystals; Microwave; Alcohol; Selectivity; Equilibrium; Porous material; Molecular sieve; Lifetime; Olefin; Pore; Transition state; Alkanol; Silicon; Diffusion; Ethylenic compound; Hydrothermal condition; Methanol
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c3cp52247d

Nano-SAPO-34 molecular sieves synthesized in a microwave environment with 20 nm crystal size showed a longer lifetime than SAPO-34 prepared by the conventional hydrothermal method in the reaction of methanol to olefins. It has been found that silicon distribution strongly affects the lifetime and selectivity. Thus, silicon at the border of the silicon islands gives a higher lifetime and lower C2/C3 ratio. This change in activity and selectivity is better explained in terms of different silicon distribution than by preferential diffusion of ethene through the 8MR pores and agrees with transition-state selectivity. The effects of equilibrium of olefins and deactivation by coke were isolated, showing that after full formation of the hydrocarbon pool, selectivity is independent of deactivation by coke.