UV185+254nm辐照下MnOx-TiO2分解甲醛与臭氧的机理

为提高185nm真空紫外光下甲醛与副产物臭氧的分解效率,以MnOx-TiO2复合催化剂取代TiO2光催化剂,发现甲醛与臭氧的转化率分别从44.7%和38.7%提高到77.5%和96.8%.研究比较了真空紫外光下和暗态下(加臭氧)甲醛与臭氧在MnOx-TiO2催化剂上的分解性能,及UV254nm下光催化分解甲醛的效率.结果表明,真空紫外光下气相活性氧物种的氧化与MnOx表面的臭氧催化氧化过程是甲醛分解的主要途径,而MnOx-TiO2上光催化氧化甲醛效率很低;副产物臭氧主要于MnOx表面活性位上由热催化分解.用真空紫外光辐照MnOx-TiO2催化剂,可提高MnOx催化分解臭氧的稳定性.

Study on the decomposition mechanism of formaldehyde and ozone byproduct in the presence of MnOx-TiO2 catalyst under UV185+254nm irradiation

To increase the efficiency of simultaneous removal of formaldehyde and ozone byproduct under 185nm VUV(vacuum ultraviolet) irradiation,TiO2 supported manganese oxide catalyst(MnOx-TiO2) was synthesized and used as photocatalyst.The conversion rate of HCHO and O3 byproduct significantly increased from 44.7% and 38.7% for TiO2 to 77.5% and 96.8% for MnOx-TiO2,respectively.To elucidate the decomposition mechanism of HCHO and O3 on the MnOx-TiO2 under VUV irradiation,the decomposition rates of HCHO and O3 under VUV irradiation and in dark condition(added O3) were compared,and the photocatalytic degradation of HCHO on the MnOx-TiO2 under UV254nm irradiation was also investigated.The results indicated that the HCHO was mainly oxidized via homogeneous oxidation with active oxygen species and heterogeneous catalytic oxidation with ozone on the MnOx surface.Only less than 10% HCHO could be photocatalytically degraded on the MnOx-TiO2 under UV245nm irradiation.The O3 byproduct was mainly removed via thermal catalytic decomposition on the MnOx surface.The stability of MnOx-TiO2 to catalytically decompose O3 was greatly improved when the MnOx surface was irradiated with VUV light.