制备条件对SO_4^(2-)/TiO_2-La_2O_3固体超强酸催化剂硫含量的影响

Effect of Preparation Conditions on Sulfur Content of SO_4^(2-)/TiO_2 -La_2O_3 Solid Superacid Catalyst

利用硫酸钡重量法对SO42-／TiO2-La2O3固体超强酸催化剂中的硫含量进行了分析。结果表明,随焙烧温度的升高,SO42-/TiO2-La2O3催化剂存在一个SO42-的快速流失温度区,并与晶相转变温度相对应。此外,原料配比n(La3+)／n(Ti4+)、硫酸浸溃浓度、硫酸浸溃时间和焙烧时间等制备条件对SO42-／TiO2-La2O3催化剂中的硫含量都存在较大的影响。SO42-／TiO2-LaO3催化剂的适宜制备条件为:原料配比n(La3+)／n(Ti4+)=1／34,硫酸浸溃浓度0.8mol／L,硫酸浸渍时间24 h,焙烧温度480℃,活化时间3 h。

Gravimetry of BaSO4 was used to determine the sulfur content of SO42-/TiO2 -La2O3. During calcinations, when temperature was rising, there existed a temperature range within which sulfur content decreased substantially. This temperature range was correspondent to the temperature of crystalline phase transition. Sulfur content was affected by other preparation conditions such as mole ratio n (La3 + )/n (Ti4+ ), soaked concentration of H2SO4,soaked time of H2SO4,and calcination time.The optimum conditions were:mole ratio n (La3+ )/n (Ti4+ ) 1/34, soaked concentration of H2SO4 0.8 mol/L, soaked time of H2SO4 24 h, calcination temperature 480 ℃, and calcination time 3 h.