INVESTIGATION OF THE PHYSICOCHEMICAL AND CATALYTIC PROPERTIES OF MFI TYPE ZEOLITES SYNTHESIZED USING DEEP EUTECTIC SOLVENT

Abstract

Zeolites of the structural type ZSM-5 were synthesized using a template, which was pentaerythritol (PER), carbamide (CA), or a deep eutectic solvent (DES) - a binary mixture of PER and CA. It is determined by IR spectroscopy and X-ray diffraction analysis that the nature of the templates used in the synthesis of zeolites affects the phase purity and the degree of crystallinity of the obtained samples. The textural and acidic properties of zeolites and Mo-containing catalysts prepared from them by dry mechanical mixing with nanoscale molybdenum powder have been studied. It is shown that the textural properties of zeolites depend on the template nature. The use of CA promoted obtaining the zeolite with maximal specific surface area and pore volume. The strength of the acid centres of unmodified samples, depending on the structure-forming additive, decreases in the series: DES > CA > PER, and the concentration of acid centres of both types, on the contrary, decreases for zeolites in the series: PER > CA > DES. The catalytic activity of synthesized zeolites has been studied in the processes of non-oxidative methane conversion and refining of the straight-run gasoline fraction of oil. The dependence of the activity and stability of samples on their physicochemical properties caused by the template nature is determined. It has been shown that zeolite synthesized using DES and the 4.0%Mo/ZSM-5 catalyst obtained on its basis exhibit higher activity and stability in the processes of non-oxidative methane conversion into aromatic hydrocarbons and in upgrading the straight-run gasoline fraction of oil, in comparison with zeolite-based catalysts obtained using PER or CA.