助剂及载体对MoO_3·M_xO_y/SiO_2 催化剂性质及甲烷部分氧化性能的影响

Effect of Aids and Supports on the Activity for Partial Oxidation of Methane and Properties of MoO_3·M_xO_y/SiO_2 Catalysts

在常压下 ,以氧气为氧化剂 ,用两种不同制法的载体分别制备催化剂 (MoO3 ·MxOy/SiO2 ) ,用于甲烷部分氧化反应 ,对比结果表明用醇盐法所制SiO2 (ZSiO2 )做成的催化剂比用市售SiO2 (QSiO2 )做成的催化剂反应活性和选择性好 ,助剂V2 O5加入提高了CH4 转化率和CO2 ,CO选择性 ,降低了HCHO产率和选择性 ,B2 O3 加入提高了CH4 转化率 ,HCHO产率和其选择性 ,降低了CO2 ,CO选择性 ,TPR结果表明载体ZSiO3 的应用减少了载体表面弱酸性位 ,但助剂V2 O5和B2 O3 的加入使MoO3 与ZSiO2 发生了不同的相互作用 ,从而影响了催化剂表面的活性氧物种 ;NH3 TPD结果表明载体ZSiO3 的应用及助剂B2 O3

The effects of supports and aids on the activity for partial oxidation of methane on MoO 3·MxOy/SiO 2 catalysts were studied.MoO 3·MxOy/ZSiO 2 catalysts prepared by sol gel (alkoxide) method had higher reaction activity and selectivity than MoO 3·MxOy/SiO 2 catalysts prepared by QSiO 2 bought.It was indicated that the addition of V 2O 5 could improve the conversion of methane and selectivity of CO 2,CO,but reduced the selectivity and yield of formaldehyde greatly.The addition of B 2O 3 could increase both the conversion of methane and the selectivity for formaldehyde.TPR results indicated that ZSiO 2 and promoters caused the different interaction of MoO 3 and ZSiO 2.The results of NH 3 TPD were the uses of ZSiO 2 decreased the weak acidic positions of SiO 2 surface.But promoters B 2O 3 added up the weak acidic positions of SiO 2 surface.