Metal-organic framework-assisted synthesis of Zr-modified SAPO-34 zeolites with hierarchical porous structure for the catalytic transformation of methanol to olefins

• Published in: Catalysis science & technology 2022-02, Vol.12 (3), p.894-95
• Main Authors: Yao, Jihui, Rong, Yuzi, Gao, Zeyan, Tang, Xiaohua, Zha, Fei, Tian, Haifeng, Chang, Yue, Guo, Xiaojun
• Format: Article
• Language: English
• Subjects: Alkenes; Aluminum; Ammonia; Catalysts; Catalytic converters; Crystallization; Fixed bed reactors; Fixed beds; Mass transfer; Metal-organic frameworks; Methanol; Morpholine; NMR spectroscopy; Optimization; Selectivity; Structural hierarchy; Zeolites; Zirconium
• ISSN: 2044-4753; 2044-4761
• DOI: 10.1039/d1cy01838h

To introduce a hierarchical porous structure into SAPO-34 zeolites and adjust their acid properties and crystalline size, a series of Zr-modified SAPO-34 zeolites (Zr x -SAPO-34 ( x = 0.25, 0.50 and 0.75)) with hierarchical porous structure were synthesized by hydrothermal crystallization using palygorskite as a silicon and partial aluminum source, morpholine and tetraethylammonium hydroxide as organic structure directing agents and UiO-66 as a co-template agent. The obtained catalysts were characterized via XRD, SEM, TEM, EDX, N 2 -adsorption-desorption, NH 3 -TPD, FTIR, Py-IR, XRF, 29 Si MAS NMR and TG analyses. The catalytic performance of Zr x -SAPO-34 in the methanol-to-olefin (MTO) transformation was investigated in a fixed bed reactor. The introduction of a hierarchical porous structure effectively enhanced the diffusion and mass transfer of the reactants/products, prolonging the catalytic lifetime. Additionally, the optimization of the acidity dramatically improved the selectivity for light olefins. Under the reaction conditions wherein the reaction temperature was 400 °C, the feed of WHSV was 2.0 h −1 , the mass of the catalyst was 0.5 g and at atmospheric pressure, the Zr 0.50 -SAPO-34 zeolites exhibited optimum catalytic performance, where the methanol conversion was 100%, the light olefin selectivity was 98.66% and the catalytic lifetime was more than 1500 min. Zr-Modified SAPO-34 zeolites with hierarchical porous structure were synthesized in the presence of UiO-66. The Zr 0.50 -SAPO-34 zeolites exhibited long lifetimes (>1500 min) and excellent selectivity for light olefins (98.66%) in the MTO reaction.