Ru/SBA-15 catalysts for partial hydrogenation of benzene to cyclohexene: Tuning the Ru crystallite size by Ba

Ru–Ba/SBA-15 catalysts with different Ba/Ru molar ratios were prepared by the ‘two solvents’ method, which can readily introduce the active components into the channels of SBA-15. Characterizations revealed that the crystallite size of Ru was tuned smoothly from 3.6 to 7.5 nm by increasing the Ba/Ru ratio from 0.1 to 1.0. In liquid phase hydrogenation of benzene, the maximum yield of cyclohexene was obtained on the Ru–Ba/SBA-15 catalyst with Ru crystallite size of 5.6 nm, which is interpreted as the presence of the highest population of the active sites favorable for the production of cyclohexene on such Ru crystallites.