<i>n</i>-Butene Synthesis in the Dimethyl Ether-to-Olefin Reaction over Zeolites

• Main Authors: Toshiaki Hanaoka, Masaru Aoyagi, Yusuke Edashige
• Format: Article
• Language: English
• Published: MDPI AG 2021-06-01
• Series: Catalysts
• Subjects: dimethyl ether; <i>n</i>-butene; zeolite; strong acid; micropore
• Online Access: https://www.mdpi.com/2073-4344/11/6/743

Zeolite catalysts that could allow the efficient synthesis of <i>n</i>-butene, such as 1-butene, <i>trans</i>-2-butene, and <i>cis</i>-2-butene, in the dimethyl ether (DME)-to-olefin (DTO) reaction were investigated using a fixed-bed flow reactor. The zeolites were characterized by N₂ adsorption and desorption, X-ray diffraction (XRD), thermogravimetry (TG), and NH₃ temperature-programmed desorption (NH₃-TPD). A screening of ten available zeolites indicated that the ferrierite zeolite with NH₄⁺ as the cation showed the highest <i>n</i>-butene yield. The effect of the temperature of calcination as a pretreatment method on the catalytic performance was studied using three zeolites with suitable topologies. The calcination temperature significantly affected DME conversion and <i>n</i>-butene yield. The ferrierite zeolite showed the highest <i>n</i>-butene yield at a calcination temperature of 773 K. Multiple regression analysis was performed to determine the correlation between the six values obtained using N₂ adsorption/desorption and NH₃-TPD analyses, and the <i>n</i>-butene yield. The contribution rate of the strong acid site alone as an explanatory variable was 69.9%; however, the addition of micropore volume was statistically appropriate, leading to an increase in the contribution rate to 76.1%. Insights into the mechanism of <i>n</i>-butene synthesis in the DTO reaction were obtained using these parameters.