Supported Pt and Pd catalysts were examined for selective hydrogenation of 1-naphthol to form tetrahydronaphthol (THNol). Five kinds of supports were used: HY zeolite with SiO2/Al2O3 of 40, HM zeolite with SiO2/Al2O3 of 38, γ-Al2O3, SiO2 and TiO2. Among these five supports, only TiO2-supported catalysts displayed selectivity for 1-naphthol hydrogenation towards 1,2,3,4-THNol. Under the same reaction conditions, Pd/TiO2 catalysts show much higher catalytic activity and higher selectivity to 1,2,3,4-THNol than Pt/TiO2 catalysts, and more tetralin was observed in product distribution for Pd catalysts. On the other hand, Pt/TiO2 showed higher selectivity for 5,6,7,8-THNol. By using Pt and Pd bimetallic catalysts, much higher selectivity to 1,2,3,4-THNol has been achieved. Product distribution depends strongly on Pt/Pd ratio. The selectivity of 1,2,3,4-THNol decreases with the increase in Pt/Pd weight ratio. The bimetallic catalyst with Pt/Pd weight ratio of 0.3 shows the highest 1,2,3,4-THNol selectivity up to 22.6 mol% at 150 °C, 500 psi and 60 min. Tetralone has been found to be an intermediate for hydrogenation of 1-naphthol to 1,2,3,4-THNol. Further hydrogenation of 1,2,3,4-THNol towards tetralin is much faster than that of 5,6,7,8-THNol.
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