MoO3/TiO2-Al2O3催化剂表面结构的LRS研究

负载型Mo和Co-Mo催化剂由于工业上的广泛应用,多年来一直是催化工作者的重要研究课题.工业上应用的Mo和Co-Mo催化剂多以活性Al_2O_3和SiO_2-Al_2O_3为载体,近年来也有用TiO_2,ZrO_2和活性碳作为催化剂载体的研究报导.有关催化剂活性组分与载体之间相互作用对催化剂表面相结构和催化性能的影响方面研究已引起人们的重视。我们多年来在金属-载体相互作用研究基础上,以石油加氢精制催化剂为应用背景,开

RAMAN SPECTROSCOPIC STUDY OF MoO_3/TiO_2-Al_2O_3 CATALYST

Raman spectrum was used to characterize the structure of Mo species supportedon TiO_2-modified Al_2O_3. For Mo/Al_2O_3 without TiO_2 samples the bands at 325-350 cm~(-1) and 930-940 cm~(-1) assigned as tetrahedral MoO_4~(-2), and the bands at 215 and950 cm~(-1) as octahedral MoO_6~(-6) can be observed at lower MoO_3 loading, whileAl_2(MoO_4)_3 phase and crystalline MoO_3 appeared respectively at 370, 1004 cm~(-1) and822,991cm~(-1) when the amount of MoO_3 was beyond one monolayer dispersion onAl_2O_3 surface. As for Mo/TiO_2-Al_2O_3 samples, only octahedral MoO_6~(-6) and crystallineMoO_3,but no tetrahedral MoO_4~(-2) and Al_2(MoO_4)~3 phases had been detected at low orhigh MoO_3 loadings, even calcination temperature of the samples raised to 973 K,which reveals that TiO_2 covered on Al_2O_3 can weaken the interaction between MoO_3and Al_2O_3, and inhibits the formation of Al_2(MoO_4)_3 phase. When a definite amountof CoO added into molybdena samples the bands of crystalline MoO_3 disappeared,suggesting that CoO can effectively promote the dispersion of MoO_3 on the carrier.The presence of CoMoO_4 phase was observed in Al_2O_3 or TiO_2-Al_2O_3 carriers.