Synthesis and characterization of BZSM-5 and its catalytic performance in the methanol to hydrocarbons reaction

doi:10.1016/j.cjche.2020.09.008

Abstract

Abstract: Five kinds of BZSM-5 molecular sieve with different Si/B ratio and a SiZSM-5 molecular sieve were prepared by hydrothermal synthesis method followed by acid exchange and pelletization. The samples were characterized by XRD, SEM, FT-IR, ICP, low temperature N₂ physical adsorption and desorption, NH₃-TPD and Py-IR. The catalytic performance in the reaction of methanol to hydrocarbons was evaluated in the fixed bed reactor. Compared with SiZSM-5, the amount and strength of Brönsted (B) acid were enhanced by introducing skeleton boron and the activity of the catalyst was greatly improved. The characterization and evaluation results indicated that the BZSM-5 catalyst synthesized from the gel of SiO₂/B₂O₃ 20 with Si/B ratio 74.48 had modest acidity strength, acid amount of 0.18mmol NH₃·g^-1 and large mesopore volume of 0.23cm³·g^-1. The B acid ratio was higher and the acid strength of BZSM-5 was weaker than that of AlZSM-5, which could inhibit the deep coke formation and increase the activity stability. B-2 had the best lifetime which could reach 672h under the same evaluation reaction conditions, due to the best matching of moderate acidity and good diffusion properties.

Key words: ZSM-5, Catalysis, Methanol, Hydrocarbons

摘要： Five kinds of BZSM-5 molecular sieve with different Si/B ratio and a SiZSM-5 molecular sieve were prepared by hydrothermal synthesis method followed by acid exchange and pelletization. The samples were characterized by XRD, SEM, FT-IR, ICP, low temperature N₂ physical adsorption and desorption, NH₃-TPD and Py-IR. The catalytic performance in the reaction of methanol to hydrocarbons was evaluated in the fixed bed reactor. Compared with SiZSM-5, the amount and strength of Brönsted (B) acid were enhanced by introducing skeleton boron and the activity of the catalyst was greatly improved. The characterization and evaluation results indicated that the BZSM-5 catalyst synthesized from the gel of SiO₂/B₂O₃ 20 with Si/B ratio 74.48 had modest acidity strength, acid amount of 0.18mmol NH₃·g^-1 and large mesopore volume of 0.23cm³·g^-1. The B acid ratio was higher and the acid strength of BZSM-5 was weaker than that of AlZSM-5, which could inhibit the deep coke formation and increase the activity stability. B-2 had the best lifetime which could reach 672h under the same evaluation reaction conditions, due to the best matching of moderate acidity and good diffusion properties.

关键词: ZSM-5, Catalysis, Methanol, Hydrocarbons

Junhua Gao, Keming Ji, Hao Zhou, Jiayao Xun, Zenghou Liu, Kan Zhang, Ping Liu. Synthesis and characterization of BZSM-5 and its catalytic performance in the methanol to hydrocarbons reaction[J]. Chinese Journal of Chemical Engineering, 2021, 35(7): 196-203.

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