论文部分内容阅读
本文对多种Na~+沸石上正庚烷裂解进行了考察。发现在所考察的沸石上正庚烷裂解都是按类自由基机理进行的,并且Na~+沸石上裂化活性随反应时间的增长下降得比酸性催化剂慢。实验结果还表明,这些沸石上正庚烷自由基裂解活性随沸石的硅铝比增加而降低,即裂解活性与沸石中Na~+含量有关。似乎这类沸石结构上钠离子代表着沸石产生自由基的能力,它可能就是这类反应的活性中心。另外,随着硅铝比的增大,Na~+沸石活性虽然减弱,但裂解产品分布特征,却愈趋近典型自由基热裂化,很可能在Na~+沸石裂解过程中,实质上既存在类自由基裂解,也同时存在典型自由基热裂解。用重质油为原料在NaY沸石上进行了探索性试验,发现在裂解产物中,有可能得到较多的柴油馏分,而产品中的汽油部分,在常压非临氢条件下在HzSM-5上改质后,其辛烷值能得到大幅度的提高。
In this paper, a variety of Na ~ + zeolite n-heptane cracking were investigated. It was found that the n-heptane pyrolysis on the investigated zeolites was based on the free radical mechanism, and the cracking activity on zeolite Na ~ + decreased with the increase of reaction time slower than that of acidic catalysts. The experimental results also showed that the activity of free radical cleavage of n-heptane on these zeolites decreased with the silica-alumina ratio of the zeolites, that is, the cleavage activity was related to the content of Na ~ + in the zeolites. It seems that the zeolite structural sodium ion represents the ability of the zeolite to generate free radicals, it may be the active center of such reactions. In addition, although the activity of Na ~ + zeolite decreases with the increase of Si / Al ratio, the distribution characteristics of the pyrolyzed products are approaching that of typical free radical thermal cracking. It is probable that Na + zeolite is essentially present in the pyrolysis of Na ~ + zeolite Free radical cleavage, there are also typical free radical pyrolysis. Exploratory tests on NaY zeolites using heavy oil as raw materials found that more diesel fractions were obtained in the pyrolysis products and that the gasoline fraction of the product was freed of nitrogen at atmospheric pressure in the presence of HzSM-5 On the modified, its octane number can be greatly improved.