GRANULAR HIERARCHICALLY POROUS Mo-CONTAINING ZSM-5 ZEOLITES WITH DIFFERENT LEVEL OF ACIDITY IN NON-OXIDATIVE CONVERSION OF METHANE TO AROMATIC HYDROCARBONS

The relevance of the work is related to the development of active and selective catalysts for processing natural and petroleum associated gases, the main component of which is methane, into valuable chemical products. Methane non-oxidative conversion into aromatic hydrocarbons on zeolite-containing catalysts modified with metals is of the greatest interest. The aim of this work is comparative study of physicochemical and catalytic properties in methane non-oxidative conversion into aromatic hydrocarbons of Mo-containing catalysts based on granular zeolites ZSM-5 of a high degree of crystallinity with a hierarchical porous structure before and after dealuminating with aqueous solution of citric acid. Methods: X-ray fluorescence analysis, XRF, SEM, nitrogen low-temperature adsorption, temperature-programmed desorption of ammonia (TPD-NH3), gas chromatography. Results. The paper presents the results of the investigation of physicochemical and catalytic properties of granular hierarchically porous Mo-containing ZSM-5 zeolites with different level of acidity in the course of non-oxidative conversion of methane to aromatic hydrocarbons. It is shown that catalysts based on a granular high crystalline ZSM-5 zeolite with a hierarchical porous structure are more effective in the nonoxidative conversion of methane compared to a catalyst prepared by a traditional method with a binder. It was found out that the highest methane conversion and the maximum yield of aromatic hydrocarbons are 18,3 and 14,4 %, respectively. These results are achieved over a catalytic system prepared by applying 4 wt. % of MoO3 on a granular hierarchically porous ZSM-5 zeolite of high crystallinity dealuminated by the treatment with 0,3 N citric acid solution. The maximum total selectivity of formation of aromatic hydrocarbons is observed on the Mo/ZSM-5mmm catalyst. At the same time, the selectivity of aromatic hydrocarbons on the catalysts Mo/ZSM-5mmm and Mo/ZSM-5mm/CA differ slightly.