硼掺杂方式对活性氧化铝性质与结构的影响

Influence of boron doping methods on properties and structure of activated alumina

采用溶胶-凝胶法和浸渍法合成四种B掺杂的活性氧化铝试样,研究了各试样的性能和结构。利用XRD、TEM、FTIR、^(27)Al NMR、N_2吸附-脱附表征等方法对试样的微观结构和表面酸性等进行表征。表征结果显示,以不同方式掺杂B未造成γ-Al_2O_3结构的改变;B的加入有效增大氧化铝的比表面积,经B改性的活性氧化铝以弱酸和中强酸为主。实验结果表明,在氢氧化铝阶段引入B的QY试样比表面积最大,粒径最小,含Ⅰ型羟基数量最多,表面弱酸含量和强酸含量最高,中强酸含量最低,且具有五配位铝离子的存在,是适宜的催化剂载体。

Four B-doped activated alumina samples were synthesized by using a sol-gel method and an impregnation method,and the properties and structure of each sample were studied.The microstructure,surface acidity and the like of each sample were characterized by such methods as XRD,TEM,FTIR,27A 1 NMR and N2 adsorption-desorption.The characterization results demonstrated that different B doping methods did not cause any change in the structure o f y-A 120 3,the addition of B effectively increased the specific surface area of the alumina,and the B modified activated alumina mainly contained weak acid and middle strong acid.The experimental results indicated that the sample QY(B was introduced in the phase o f aluminum hydroxide)had the largest surface area,the smallest particle size and the most type I-OH groups,and the highest weak acid amount and strong acid amount on the surface,and was an appropriate catalyst carrier due to the presence of penta-coordinate aluminum ion.