Liquid-phase selective hydrogenation of benzene to cyclohexene on Ru/Al2O3-ZrO2/cordierite monolithic catalysts

Monolithic catalysts, Ru/Al2O3-ZrO2/cordierite, were prepared by dipcoating and impregnation for liquid-phase selective hydrogenation of benzene to cyclohexene in a continuous fixed bed reactor. Ru/Al2O3-ZrO2/cordierite showed excellent catalytic performance due to the high specific surface area and the large pores of Al2O3-ZrO2 support. The Zr/Al ratio was optimized to be 0.116 and the excessive amount of ZrO2 resulted in a decreased specific surface area of the Al2O3-ZrO2 washcoating layer. The preferable calcination temperature is 1373 K for Al2O3-ZrO2 support, at which suitable BET surface area and pore size distribution could be obtained. It was also found that appropriate ratio of Zn/Ru was essential to obtain high selectivity. Additionally, compared to the powder catalysts used in the slurry reactor, the monolithic catalysts exhibited much higher activity regarding the yield of cyclohexene and cyclohexane. (C) 2009 Elsevier B.V. All rights reserved.