Synthesis, Preparation and Catalytic Activities of V-doped TiO_2 Gel Coating on Porous α-AI_2O_3 Beads

摘要

TiO_2 and V-doped TiO_2 gel were synthesized and coated onto porous α-Al_2O_3 beads to study the thermal catalytic activities of oxidation reactions. Titanium isopropoxide (Ti(OPr)_4) and l,2-butadiol(Bu(OH)_2) were used as starting chemicals for preparation of TiO_2 gel without V-doping. After aging at ambient temperature for one week, a TiO_2 gel was obtained. The concentration of Ti(OPr)_4 was varied, 0.2, 0.3, 0.7 and 2.4 M was used. For V-doping of the TiO_2 gel, 0.05, 0.20 and 0.75 mole% of V was prepared by ultrasonically dissolving vanadium acetylacetone (V(acac)_2) in 1,2-butadiol. The solutions were then added to Ti(OPr)4. Finally, the mixed solutions were kept under ambient temperature for one week to form the V-doped Tio_2 gel. TiO_2 and V-doped TiO_2 were calcined at 300, 400, 500, 600, 700, and 800 °C. XRD analysis, SEM and TEM in conjunction with EDS analysis were used to identify the phases present, grain size and morphology. The TiO_2 grains have a particle size in the nano-scale range. Doping TIO_2 with V could retard growth of the TiO_2 particles and affect phase transformation at higher calcination temperatures. Both the TiO_2 and V-doped TiO_2 gels were prepared and coated onto α-Al_2O_3 beads to test oxidation reactions in a purpose-designed reactor. The results of the catalytic reactions indicated that V-doped TiO_2 had a higher oxidation activity than the undoped TiO_2 gel. The content of vanadium was related to the reaction efficiency.