FCC汽油重馏分的单分子和双分子裂化反应特征产物的生成途径 Ⅱ.特征产物在不同类型催化剂上的生成途径

THE REACTION PATHS OF CHARACTERISTIC PRODUCTS FROM MONOMOLECULAR AND BIMOLECULAR CRACKING REACTION OF HEAVY FRACTIONS OF FCC GASOLINE Ⅱ.The Formation Paths of Characteristic Products Over Different Type Catalysts

以FCC汽油重馏分为原料,采用不同类型的酸性催化剂,在小型固定流化床装置上进行催化裂化反应类型实验,反应温度为400-520℃。结果表明,干气组成随反应温度和酸性催化剂的不同而具有明显的差别。由此首先讨论了五配位正碳离子尤其是乙烯的不同的断裂方式;其次,以裂化机理比率(CMR)为基础,估算了丙烷、正丁烷、异丁烯等特征产物来自单分子裂化、双分子裂化和双分子氢转移反应的比例。计算表明,随着反应温度和酸性催化剂的不同,各反应的比例不同;单分子反应对C3、C4等产物的组成也有影响。

With the heavy fraction of FCC naphtha as feedstock, the experiments were conducted in a fixed-fluidized bed reactor over different type of acid catalysts respectively in a reaction temperature range of 400-520℃. The results showed that the volume composition in produced dry gas was entirely different at different temperatures and over different catalysts. According to the results, the cracking reaction routes of olefins, especially ethylene, via the intermediate pentacoordinated carbonium ions over the acid catalysts were first discussed. Then based on the cracking mechanism ratio（CMR）, the proportions of propane, n-butane and i-butene, cracked by the monomolecular cracking reaction, the bimolecular cracking and hydrogen transfer reaction, respectively, were calculated. It was shown that the values of CMR at different temperatures were distinctly dissimilar and the volume composition of C3, C4 was also influenced by monomolecular cracking reaction.