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以介孔硅基分子筛(MCM-41)为载体,采用溶胶-凝胶法制备分子筛负载型TiO2催化剂。针对催化剂在负载前后及煅烧阶段对其晶型、晶粒及催化活性的影响,从煅烧成型工艺和XRD、TEM表征的角度进行研究;以酸性红B为模拟降解物,通过对分子筛负载型TiO2催化剂的活性评价,从煅烧温度、煅烧时间及碳化效应3个方面考察对催化剂活性的影响。结果表明,在600℃下煅烧2 h制备的负载型催化剂的活性最高,催化剂投加量0.5 g/L,光催化反应2 h对50 mg/L的酸性红B的降解率达93%。分子筛负载TiO2在高温煅烧阶段能够有效抑制锐钛相晶型的转变及TiO2纳米晶粒的尺寸,增加单位质量活性位的个数,提高催化性能。煅烧成型阶段空气通入量和升温速度对催化剂活性影响显著,缺氧、无氧及过快的升温速度都会导致碳化效应的产生,严重降低催化剂光催化性能。
A mesoporous silica-based molecular sieve (MCM-41) was used as a carrier to prepare a molecular sieve supported TiO2 catalyst by a sol-gel method. According to the influence of the catalyst on the crystalline form, crystal grain and catalytic activity of the catalyst before and after the calcination, the calcination process and the characterization of XRD and TEM were carried out. The acidic red B was used as a simulated degradation product, The activity of the catalyst was evaluated, and the influence on the catalyst activity was investigated from three aspects of calcination temperature, calcination time and carbonization effect. The results showed that the catalyst prepared by calcination at 600 ℃ for 2 h exhibited the highest catalytic activity with a catalyst dosage of 0.5 g / L. The degradation rate of acid red B with 50 mg / L was 93% after 2 h of photocatalytic reaction. The molecular sieve supported TiO2 can effectively inhibit the transformation of anatase phase and the size of TiO2 nanocrystals during calcination at high temperature, increase the number of active sites per unit mass and improve the catalytic performance. The air entrainment rate and heating rate in the calcination stage have a significant effect on the catalyst activity. The hypoxia, anaerobic and overly rapid heating rate will lead to the carbonation effect, which will seriously reduce the photocatalytic activity of the catalyst.