Home – Home – Jornals – Chemistry for Sustainable Development 2020 number 3

Rhenium containing catalysts are prepared on the basis of high-silica zeolite of pentasil family with a silicate modulus 40. Modification of the zeolite with rhenium introduced using various methods results in the changes in its structural characteristics: a decrease in specific surface area, pore volume and diameter. The most noticeable decrease in these parameters is observed when impregnation and ion exchange are used. The use of rhenium-containing zeolite catalysts for upgrading the straight-run gasoline fraction of oil allows increasing the yield of liquid products - high-octane gasolines characterised by a low content of aromatic hydrocarbons and a high octane number. A decrease in the aromatizing activity of Re-containing catalysts contributes not only to improvements in the environmental characteristics of resulting gasolines but also into an increase in the time of the stable operation of catalysts. Due to an increase in the rate of hydrogenation, the introduction of rhenium significantly reduces the amount of coke deposits formed on the catalysts under study during the process. According to the rate of formation of coke deposits, Re/MFI catalysts prepared using different methods are ranked as follows: ion exchange < ultrafine powder < impregnation < mixing with salt < MFI. Carbon densification products formed on rhenium-containing catalysts are less condensed and more homogeneous than coke obtained on unmodified zeolites. According to the degree of decrease in catalytic activity or aromatizing ability during the same time of operation, the catalysts under study may be ranked as follows: MFI > Re/MFI (ion exchange) > Re/MFI (ultrafine powder) > Re/MFI (impregnation) > Re/MFI (mixing with salt).