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A Ru-Mo bimetallic catalyst was developed by decorating Ru NPs with mononuclear Mo5+Ox for the selective hydrodeoxygenation (HDO) of amides to amines, where the C O bond of amide is selectively activated on the low-coordinated mononuclear Mo5+Ox sites and the HDO reaction proceeds at the interface of Ru and Mo5+Ox. [Display omitted] • A highly active, selective and stable RuMo/SiO 2 catalyst with Ru nanoparticles of ∼ 2 nm decorated with mononuclear Mo5+Ox has been developed for the HDO of primary amides to amines. • The catalytic performance relies critically on the Mo/Ru ratio, and high activity and selectivity are only achieved when Mo/Ru ratio is smaller than 0.12 where mononuclear Mo5+Ox dominates. • The characterizations and reaction kinetics show that the C O bond of the amide is activated on the low-coordinated mononuclear Mo5+Ox species and the reaction proceeds at the MoRu interface. The selective hydrodeoxygenation (HDO) of amides is a key methodology to producing amines, yet it remains a great challenge due to the highly stable amide molecular structure. In this study a series of 2Ru x Mo/SiO 2 (x = 0 ∼ 3) catalysts were prepared with sequential impregnation method followed by reduction. The reaction tests showed that the target amine yield presented a volcano-shape dependence on the Mo content, and reached the highest value at the Mo content of 0.2 wt% which corresponded to a Mo/Ru atomic ratio of 0.11 and a Mo surface density of 0.08. By contrast, a higher Mo content resulted in dramatic decrease in both activity and selectivity. By using HAADF-STEM, X-ray absorption spectroscopy (XAS), H 2 -TPR and CO-chemisorption, the structure of the best-performance 2Ru0.2Mo/SiO 2 catalyst was identified as Ru NPs of ∼ 2 nm decorated with mononuclear Mo5+O x species, which was in contrast with the polymeric MoO 2 -like species partially covering the Ru surface for the 2Ru3Mo/SiO 2. Kinetic studies revealed that the reaction order with respect to CyCONH 2 was 1.2, −0.1 and −0.5 over the 2Ru/SiO 2 , 2Ru0.2Mo/SiO 2 and 2Ru3Mo/SiO 2 , respectively, which indicated amide was selectively activated on the low-coordinated Mo5+O x sites while H 2 was activated on the Ru sites and the reaction proceeded at the Mo-Ru interface. The turnover frequency based on interfacial Ru-Mo sites reached 407.8 h−1, which was more than twofold higher than that of Ru-W system (175.6 h−1) we previously reported. [ABSTRACT FROM AUTHOR]

Catalytic hydrogenation of CO 2 to methane was investigated over Ru/rutile TiO 2 , focusing on the influence of the pretreatment temperature on the activity. Rutile TiO 2 stabilized Ru nanoparticles even after pretreatment at 800 °C; therefore it was possible to establish the structure–activity relationship without considering the particle size effect. The CO 2 turnover frequency initially increased with increasing pretreatment temperature from 300 to 800 °C, and reached a maximum value of 1.59 s −1 on Ru/rutile TiO 2 pretreated at 600 °C; it decreased to 1.16 s −1 for the sample pretreated at 800 °C. The characterization results indicated that the activity depended on both the extent of encapsulation of Ru particles by TiO x layers and the number of hydroxyl groups on the TiO x surface. The mechanism of CO 2 methanation was discussed based on in situ diffuse-reflectance infrared Fourier-transform spectroscopy results. [ABSTRACT FROM AUTHOR]