Reduction of Menthone with Isopropanol in the Presence of Palladium on Sibunit (ICT-3-31)
Catalysis in Industry
, E-ISSN: 2070-0555
||palladium on sibunit, hydrogen transfer reaction, reduction of ketones, menthone, menthol, dehydration, dehydrogenation
Philippov A. A.
Chibiryaev A. M.
Boreskov Institute of Catalysis, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Novosibirsk State University, Novosibirsk, 630090 Russia
Federal Agency for Scientific Organizations
The catalytic properties of the industrial “palladium on sibunit” catalyst (ICT-3-31, 0.5 wt % Pd) were studied in the reduction of menthone into menthol. Menthone was reduced both at 250 and 350°C using isopropanol as an H-donor under the conditions of the hydrogen transfer reaction (HTR). For comparison, a noncatalytic reaction was performed under the same conditions. At 350°C the conversion of menthone was the same (61–62%) in the presence of the catalyst and without it. In the reaction with the catalyst, the selectivity on the desired product menthol decreased considerably (from 98% down to 23%), and the amount of the by-products increased (from 2 up to 77% based on changed menthone). When the temperature of the catalytic reaction was lowered to 250°C, the reduction selectivity increased to 42%, but the conversion of menthone decreased to 10%. All the products of menthone conversion were identified and pathways of their formation suggested. At 250–350°C the carbon support sibunit catalyzed the dehydration of menthone, which hindered the satisfactory yields of the target alcohol. Other side reactions catalyzed by ICT-3-31 were dehydrogenation into p-menthenes and their further aromatization resulted in the formation of substituted benzenes—p-cymene and thymol. ICT-3-31 can be effectively used in HTR, if more reactive organic substrates are involved in the reaction below 200–250°C or stronger H-donors are applied.