炭分子筛的制备及表面结构
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摘要: 以大庆石油焦为原料，采用KOH活化法，考察了碱炭比、活化温度、活化时间对吸附性能的影响，确定最佳工艺条件，碱炭比4∶1、活化温度800 ℃、活化时间2 h。并制得比表面积大于3 000 m2/g的超级活性炭。通过热处理得到孔径均一(中孔率＞85%)，比表面积大于1 500 m2/g的炭分子筛；再用表面氧化方法，得到表面酸度适宜（150 ℃～240 ℃之间为弱酸，240 ℃～340 ℃为中强酸，340 ℃～450 ℃为强酸分布）的催化剂载体。炭分子筛与传统氧化铝比较具有酸度分布广泛等特点,因较好的酸强度分布，可以增强载体与金属离子之间的作用力，增加负载量。因此，经氧化后的炭分子筛更适于作催化剂载体。Abstract: The ultra activated carbon with a surface area of more than 3 000 m2/g was obtained from Daqing petroleum coke by KOH activation. The effects of the ratio of alkali to carbon, the activation temperature and the activation time on the adsorption properties were investigated, and the preparation parameters were optionized (KOH∶C=4∶1,activation temperature:800 ℃,activation time:2 h). A carbon molecular sieve with a mesopore ratio>85% and SBET>1 500 m2/g was then obtained from the UAC through heat-treatment; HNO3 oxidization was employed to make CMS with acid strength distribution on the surface being appropriate (150 ℃～240 ℃ weakly acid, 240 ℃～340 ℃ middle strong acid, 340 ℃～450 ℃ strong acid). This novel CMS with wider distribution in acidity is of potential in catalyst. Because better acidities distribution can intensify the strength between supports and metal ions and increase the loadings, CMS post oxidation is more suitable for being catalyst supports.
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Key words:
- carbon molecular sieve /
- heat treatment /
- HNO3 oxidation /
- surface structure
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