from first principles PP-I-1

PP-III-45Au-Ni Synergism in the Alumina Supported Catalysts in theHydrodechlorination of ChlorobenzeneKavalerskaya N.E., Majouga A.G., Lokteva E.S., Golubina E.V., Maslakov K.I.Lomonosov Moscow State University, Department of Chemistry, Moscow, Russian.kavalerskaya@gmail.comAfter success of Haruta’s early work many researchers focus their attention on catalysis bygold. Numerous of them deals with supported gold. Different active sites were proposed forthe various catalytic systems but the nature of the active site is still unclear. For theinvestigation of catalysis by Au it’s important to choose a structure-sensitive reaction becausegold particles of narrow size region are active in catalysis. In the present work catalyticactivity of γ-Al 2 O 3 supported Au and Ni monometallic and Au-Ni bimetallic catalysts wasinvestigated in the hydrodechlorination of chlorobenzene (HDC) at 50-350 o C in the gas-phaseflow type fixed-bed system. Au particles with different size (3, 6, and 10 nm at up to 1%mass.loading) were deposited on γ-Al 2 O 3 or 6%Ni/γ-Al 2 O 3 (prepared by wet impregnation ofsupport with Ni nitrate) from the colloidal dispersions. Catalysts were examined by HR TEM,XPS, and TPR. Ni sample with high spinel content was chosen for comparison to minimizedeactivation under the influence of reaction medium, though it is hard to reduce.Catalytic activity of 6%Ni/γ-Al 2 O 3 was negligible in the low-temperature region; 100%chlolobenzene (CB) conversion was achieved only at 350°C. On Au/Al 2 O 3 CB conversionachieved maximum of 42% at 250°C with no further increase till 350°C. CB conversion onAu-Ni catalysts proceeded at lower temperature and depended on the Au particle size. Thebest catalyst (Au particles of 6 nm) demonstrated 50% conversion already at 180°C, the othertwo (Au particles of 3 and 10 nm) at 220°C, and all three samples provided 100% conversionat 250°C. Therefore synergism of action of Ni and Au in CB hydrodechlorination takes place.This fact could be explained by the changes in the metal state and was confirmed by thenegative (0,3 eV) shift of E B of Au 4f in Au-Ni (10 nm Au) sample as compared to that in Ausample. After the Au deposition temperature of Ni reduction lowered according to TPR data.This work was supported by RFBR (№ 10-03-00372, 11-03-00820) and Leading ScientificSchools grant НШ-2724.2012.3. Results were obtained with the help of SRCCU“Nanochemistry and Nanomaterials” of Lomonosov Moscow State University.198