催化剂对高岭土制备莫来石晶须的影响

Effect of Catalysts on the Preparation of Mullite Whiskers from Kaolin Clay

课题组采用廉价高岭土和氧化铝为原料,提出了以氧化硼为新型催化剂,并以氟化铝、钼酸铵等传统典型催化剂做对比,在1300℃下合成莫来石晶须。利用XRD、SEM等方法分析晶须的相组成和微观形貌,探究了三种催化剂(氟化铝、钼酸铵、氧化硼)及其添加量对莫来石晶须合成的影响。结果表明:就传统催化剂而言,氟化铝较钼酸胺的催化效果更好,添加10wt.%氟化铝的莫来石晶须长径比约为10.5;三种催化剂中氧化硼的催化效果最好,随着氧化硼掺量的增加,晶须长径比逐渐增大;当氧化硼的添加量为15wt.%时,所得晶须均为莫来石相且分布均匀,长径比为13。

The preparation of mullite whiskers based on catalytic method using inexpensive raw materials is a green and efficient method,but there is a lack of systematic study for the catalytic effect of different catalysts.In this work,mullite whiskers were synthesized at 1300°C using cheap kaolin and alumina as raw materials and boron oxide was proposed as a new catalyst,meanwhile,traditional typical catalysts such as aluminium fluoride and ammonium molybdate were used for comparison.The phase composition and microscopic morphology of the whiskers were analysed by XRD and SEM,and the effects of the three catalysts(aluminium fluoride,ammonium molybdate and boron oxide)and their addition amounts on the synthesis of mullite whiskers were investigated.The results showed that the catalytic effect of aluminium fluoride was better than that of ammonium molybdate for the conventional catalysts,and the mullite whisker aspect ratio was about 10.5 with the addition of 10 wt.%aluminium fluoride.boron oxide had the best catalytic effect among the three catalysts,and the whisker aspect ratio increased gradually with the increase of boron oxide doping.When boron oxide was added at 15 wt.%,the resulting whiskers were all mullite phase and uniformly distributed,with a aspect ratio of 13.