摘要
采用XRD、TGA,ESCA谱图研究预处理条件对浸渍法制备载钴沸石试样还原度,活性的影响,观察到载钴沸石经焙烧比未焙烧还原度减小;低载钴量试样低温焙烧比高温焙烧还原度要大,高载钴量试样高温焙烧比低载钴量还原度相对较大;升温速率为10℃/分,比20℃/分的还原度大1/4左右;还原时间一般大于10小时,还原度可达80%以上;本文对采用Co(No_3)_2溶液浸渍法制备试样还原机理进行了探讨,观察到还原度的大小,除与载钴试样的酸度、交换度、载钴量有关外,还与还原条件(升温速率,氢气的分压,还原时间等因素)有关。用m-x巽构化考察还原度与活性之的关系,其结果表明Ⅰ号载钴试样还原度小,而巽构化活性反而大,可能是由于未被还原的氧化钴和金属钴之间相互作用,致使还原度最小的Ⅰ号试样改变活性的缘故。
The effect of pretreatment conditions on the degree of reduction and activity of impregnated Co-supported zeolites has been studied by XRD, TGA and ESCA.
We found that the degree of reduction not only depended on the acidity of samples, the degree of ionexchange and the cobalt content, but also depended on the reduction conditions, such as the rate of temperature increasing, the pressure of hydrogen and the time of reduction, etc.
The relation between the degree of reduction and activity was characterised by the isomerization of meta-xylene. The results showed the degree of reduction for Sample Ⅰ was low, but isomerization activity was high. Probably the interaction between unreduced CoO and cobalt changed the activity of Sample Ⅰ.
关键词
载钴沸石
催化作用
还原度
侵渍法
Co-Supported zeolites, Catalysis, Degree of reduction, Impregnated.
