Abstract Two series of WO 3 –ZrO 2 and WO 3 –ZrO 2 –TiO 2 composite oxides were prepared via an Evaporation Induced Self Assembly (EISA) method and applied for the hydrogenolysis of glycerol after loading with Pt. Several techniques like XRD, BET, Raman spectroscopy, NH 3 -TPD, Py-IR, TEM and XPS were adopted to characterize the physicochemical properties of the as-synthesized catalysts. The structure and catalytic activities of these catalysts were significantly affected by the calcination temperature of the composite oxides. The introduction of TiO 2 into Pt/WO 3 –ZrO 2 could inhibit the drastic decrease in catalytic performance due to the formation of inactive crystalline WO 3 under high calcination temperature of 800 ℃. A maximum activity was obtained on the Pt/WO 3 –ZrO 2 –TiO 2 catalyst when the calcination temperature was 600 ℃, which gave 73.8% glycerol conversion and 25.4% 1,3-propanediol yield. While the Pt/WO 3 –ZrO 2 catalyst only exhibited 53.4% glycerol conversion and 20.2% 1,3-propanediol yield. The enhanced activity of Pt/WO 3 –ZrO 2 –TiO 2 was ascribed to the improved acidity originating from (i) higher acidic properties of WO x species when linked to Ti with larger electronegativity other than Zr and (ii) new acid centers caused by heteroatoms linkage as the combination of ZrO 2 and TiO 2 . The effects of Pt loading amount and reaction temperatures were also investigated. Graphic Abstract
Jiachun Chai,Shanhui Zhu,Youliang Cen,Jing Guo,Jianguo Wang,Weibin Fan
One-pot hydrogenolysis of cellulose to ethylene glycol (EG) was carried out on WO3-based catalysts combined with Ru/C. To probe the active catalytic site for breaking the C–C bond of cellulose, a series of WO3–ZrO2 (WZr) catalysts were synthesized and systematically characterized with XRD, Raman, UV-Vis, H2-TPR, DRIFS and XPS techniques and N2 physisorption experiment. It was found that the WO3 crystallites became more easily reduced to W5+–OH species with increasing crystallite size or tungsten surface density of the WZr catalyst owing to the decrease of their absorption edge energy (AEE) originating from weakening their interaction with ZrO2 support. This, as a result, gave higher EG yield at higher tungsten surface density. The structure–activity relationship of the WZr catalyst reveals that the active catalytic site for cleaving the C2–C3 bond of the glucose molecule is the W5+–OH species.
The catalyst of WO 3 highly dispersed on mesoporous ZrO 2 was prepared by hydrothermal treatment and calcination. Ionic liquid templates with different cations and various calcination temperatures were taken into account to investigate factors that affect the structure of the catalysts. Wide-angle XRD, Raman, low-angle XRD, N 2 adsorption–desorption, SEM, EDS-mapping and TEM analyses were employed to characterize the composition, morphology and the dispersion of WO 3 . It was found that [C 16 H 33 N(CH 3 ) 3 ] 4 SiW 12 O 40 and 700 °C were the optimal ionic liquid template and calcination temperature; the obtained catalyst, expressed as 700-C 16 -WO 3 /ZrO 2 , exhibited the best catalytic activity in oxidation desulfurization. Dibenzothiophene (DBT) in the model oil could be oxidized to DBT sulfone (DBTO 2 ) completely, certified by GC-MS analysis, under optimum conditions. The oxidative desulfurization efficiencies of different substrates catalyze by 700-C 16 -WO 3 /ZrO 2 , and the cycle performance on the oxidation of DBT were studied.
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