A decorated ruthenium catalyst was prepared by the coprecipitation method and used for the selective hydrogenation of maleic anhydride(MA) to γ-butyrolactone(GBL). The as-prepared catalyst was characterized by XRD, TGDTG and N2 adsorption techniques. The characterization tests revealed that the catalyst carrier was composed of monoclinic zirconia(m-ZrO2) and hydroxyl cobalt oxide(CoO(OH)). The hydrogenation results showed that the content of CoO(OH), the reaction temperature, the hydrogen pressure and the reaction time significantly affected the catalytic selectivity to GBL. The promotional effect of CoO(OH) was remarkable, which led to an obvious increase in GBL selectivity. An 100% MA conversion and 92.0% selectivity to GBL were achieved over the Ru/ZrO2-CoO(OH)(35%) catalyst in water solvent under the conditions involving a reaction temperature of 180 ℃, a hydrogen pressure of 3.0 MPa, and a reaction time of 6 h.
Selective hydrogenation of chloronitrobenzene(CNB) to chloroaniline(CAN) catalyzed by water-soluble Ru/Pt bimetallic catalyst in an aqueous-organic biphasic system was studied. It was found that the catalytic activity increased obviously due to the addition of platinum. Ru/Pt bimetallic catalysts exhibited a strong synergistic effect when the molar ratio of Pt was in the range of 5%—80%. Under the mild conditions including a temperature of 25 ℃, a hydrogen pressure of 1.0 MPa and a Pt molar ratio of 20%, the conversion of p-chloronitrobenzene(p-CNB) reached 99.9%, with the selectivity to p-chloroaniline(p-CAN) equating to 99.4%. The Ru/Pt catalyst also showed high activity and selectivity for the hydrogenation of other chloro- and dichloro-nitrobenzenes with different substituted positions. In addition, the catalyst can be recycled five times without significant loss of activity.
