Selective Oxidation of Toluene with Hydrogen Peroxide Catalyzed by V-Mo-based Catalyst

The selective catalytic oxidation of toluene with hydrogen peroxide over V-Mo-based catalysts under mild conditions was studied.The promotion effect of Mo on the catalysts was studied with V/Al2O3 and Mo/Al2O3 as reference samples.The catalysts were characterized by XRD,TPR,and XPS techniques.The results show that the addition of Mo to V/Al2O3 may change the distribution of V species on Al2O3 surface.Over V-Mo/Al2O3 catalyst,highly dispersed amorphous V species facilitates benzaldehyde formation,and crystalline V2O5 species increases the conversion of toluene but decreases the selectivity to benzaldehyde,while AlVMoO7 species favors both the conversion of toluene and the formation of cresols.The yield of benzaldehyde depends remarkably on the surface O/Al and Mo/V atomic ratios,and gets to a maximum value of 13.2% with a selectivity of 79.5% at an O/Al atomic ratio of 3.0 and Mo/V atomic ratio of 0.7.

铁钼氧化物TPD-MS及催化性能的研究

制备了一系列不同配比的Fe-Mo氧化物催化剂 ,采用比表面积、XRD、FT -IR和LRS等方法 ,考察了催化剂的有关物化性质 ,测定了对甲苯选择性氧化生成苯甲醛的催化活性。用TPD -MS技术研究了催化剂表面氧物种的脱附。结果表明 ,随着样品中Fe/Mo含量的改变 ,表面氧物种的脱附峰的峰温、氧脱附量和脱附活化能Ed 也发生变化。 3# 样品 (Fe/Mo =0 2 9)的氧脱附峰峰温较低 ,表面氧物种O-和O2 -脱附量最大 ,Ed 值最小 。