Regulating the size and acidity of SAPO-34 zeolites using dual templates to enhance the selectivity of light olefins in MTO
| Autor: | Fei Zha, Yue Chang, Haifeng Tian, Shizi Ma, Xiaohua Tang, Jihui Yao, Xiaojun Guo |
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| Rok vydání: | 2021 |
| Předmět: |
Olefin fiber
010405 organic chemistry General Chemistry 010402 general chemistry 01 natural sciences Catalysis 0104 chemical sciences law.invention chemistry.chemical_compound chemistry Chemical engineering law Morpholine Materials Chemistry Methanol Crystallite Crystallization Selectivity Triethylamine |
| Zdroj: | New Journal of Chemistry. |
| ISSN: | 1369-9261 1144-0546 |
| DOI: | 10.1039/d1nj01845k |
| Popis: | To understand the relationship between the catalytic performance, crystallite size, and acidity of SAPO-34 zeolites better, a series of SAPO-34 zeolites were prepared by hydrothermal crystallization using palygorskite as silicon and partial aluminum source, and selecting two kinds of triethylamine, morpholine and tetraethylammonium hydroxide as dual templates. The obtained SAPO-34 zeolites were characterized via the methods of XRD, SEM, N2-adsorption–desorption, NH3-TPD, FTIR, XRF, 29Si MAS NMR, 27Al MAS NMR and TG. The properties of the templates affected the crystal growth rate that triethylamine and morpholine can cause a larger crystallite size while tetraethylammonium hydroxide can form small crystallite size particles. The number of acid sites of SAPO-34 zeolites first decreased and then increased with the increase of morpholine. The formation of Si islands can enhance the number of acid sites of SAPO-34 zeolites. The catalytic performance of SAPO-34 zeolites in methanol-to-olefins (MTO) reaction was investigated in a fixed bed reactor. Under reaction conditions, when the reaction temperature was 400 °C, the feed WHSV was 2.0 h−1, the mass of the catalyst was 0.5 g, at atmospheric pressure, the sample with an amount of acid sites of 0.85 mmol g−1 and crystallite size of 0.84 μm exhibited the optimum catalytic performance with methanol conversion at 100%, light olefin selectivity at 97.15% and catalytic lifetime at more than 1050 min. |
| Databáze: | OpenAIRE |
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