摘要
采用热重和微商热重(TG/DTA)综合热分析技术在不同升温速率下研究了掺入La(NO3)3和Pr(NO3)3的高岭石的热分解过程,利用Coats-Redfern积分法和Achar微分法对热分析实验数据进行动力学计算,得到了高岭石脱羟基反应过程中的控制机理函数、活化能和指前因子等动力学参数;分析了2种稀土掺入对高岭石脱羟基过程动力学参数的影响,并用Ozawa法对活化能进行了验证.结果表明,未掺稀土和掺入Pr(NO3)3的高岭石的脱羟基反应过程均受化学反应模型F3控制,反应的活化能分别为307.94和282.86k J/mol,指前因子ln A的值分别为47.8980和44.1718;掺入La(NO3)3的高岭石脱羟基反应过程控制机理函数发生改变,受化学反应模型F2控制,反应活化能为196.02 k J/mol,指前因子ln A的值为29.5551.与未掺稀土的高岭石对比,掺入Pr(NO3)3后活化能和指前因子略有降低;而掺入La(NO3)3后则显著降低,分别降低了36.34%和38.30%.采用Ozawa法验证得到的活化能与Coats-Redfern积分法和Achar微分法结果一致.
The thermal decomposition processes of kaolinite mixed with La（ NO3 ） 3 and Pr （NO3 ） 3 were investigated by thermogravimetric analysis/differential thermal analysis （TG/DTA） simultaneous thermal analysis technique under different heating rates. Thermal analysis data were used for dynamic analysis by the CoatsRedfern integral method and Achar differential method to calculate the kinetic model function, activation energy and pre-exponential factor of dehydroxylation process of kaolinite. The effects of two kinds of rare earth on kinetic parameters of dehydroxylation process of kaolinite were analyzed. The activation energy was validated by Ozawa method. The results show that dehydroxylation of kaolinite and the sample mixed with Pr（ NO3 ） 3 are controlled by the rate of third-order chemical reaction （ F3 ） , the activation energies are 307.94 and 282.86 kJ/mol, respectively, and the values of pre-exponential factor lnA are 47. 8980 and 44. 1718, respectively; the kinetic model function of sample mixed with La （NO3 ）3 changes to the second-order chemical reaction （F2）, the activation energy is 196.02 kJ/mol, and the value of pre-exponential factor lnA is 29. 5551. Compared with the kaolinite without rare earth, the activation energy and the pre-exponential factor lnA of the sample mixed with Pr（ NO3 ） 3 have slightly reduced, while those of the sample mixed with La（ NO3 ） 3 significantly decrease by 36.34% and 38.30%, respectively. The value of the activation energy obtained by CoatsRedfern and Achar method is consistent with the one obtained by Ozawa method.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
2015年第7期1395-1402,共8页
Chemical Journal of Chinese Universities
基金
国家自然科学基金(批准号:51264009)
江西省自然科学基金(批准号:20122BAB206023)资助~~
