Study of the influence of the nature of the template on the physicochemical and catalytic properties of zeolites of type ZSM-5 and Mo/ZSM-5 catalysts based on them
In this work, the effect of the nature of the structure-forming additive on the physicochemical and catalytic properties of the synthesized zeolites and catalysts prepared on their basis during the non-oxidative conversion of methane to aromatic hydrocarbons was studied. Zeolites were synthesized by hydrothermal crystallization from alkaline aluminosilica gels using hexamethylenediamine (HMDA) and ammonium bicarbonate (BCA) as templates. In the case of creating a mesoporous structure of zeolites, carbon black grade P354 was added to the reaction mixtures during synthesis. The synthesized zeolites were studied by IR spectroscopy, X-ray diffraction analysis, low-temperature nitrogen adsorption, scanning electron microscopy, and temperature-programmed ammonia desorption. The catalytic properties of the samples were studied during the nonoxidative conversion of methane to aromatic compounds. It is shown that all obtained zeolites belong to the ZSM-5 type zeolite, and the addition of carbon black during their synthesis slightly affects their textural properties, increasing the volume of mesopores. When modifying zeolites with molybdenum, their specific surface area and porosity decrease. It has been found that zeolites obtained using HMDA are characterized by greater strength and a lower concentration of high-temperature acid sites compared to samples synthesized with BCA. The addition of molybdenum to zeolites leads to a decrease in the strength and concentration of both types of acid sites. It has been shown that Mo-containing catalysts obtained on the basis of zeolites with a micro-mesoporous structure are characterized by higher activity and stability in the methane dehydroaromatization reaction compared to microporous systems. Contribution of the authors: the authors contributed equally to this article. The authors declare no conflicts of interests.
Keywords
methane dehydroaromatization,
metal zeolite catalysts,
zeolite type ZSM-5,
micro-mesoporous structure,
acidityAuthors
| Budaev Zhargal B. | Tomsk State University | budaevl 7@mail.ru |
| Stepanov Andrey A. | Institute of Petroleum Chemistry, Siberian Branch of the Russian Academy of Sciences | stepanov@ipc.tsc.ru |
| Korobitsyna Lyudmila L. | Institute of Petroleum Chemistry, Siberian Branch of the Russian Academy of Sciences | kll@ipc.tsc.ru |
| Vosmerikov Alexander V. | Institute of Petroleum Chemistry, Siberian Branch of the Russian Academy of Sciences; Tomsk State University | pika@ipc.tsc.ru |
Всего: 4
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