催化汽油选择性加氢脱硫工艺中床层结焦机理

Mechanism of Coke Formation on Catalyst Bed of FCC Gasoline Selective Hydrodesulfurization

采用SEM、XRD、FT-IR、XPS等表征手段分析了FCC汽油选择性加氢脱硫工艺中床层结焦的结构和形态,并由此探讨了结焦机理。结果表明,焦的外观表现为松散的簇状物质,为无定型焦炭包裹在铁的硫化物外的结构;无定型焦炭由高度聚合的烯烃及高度缩合的芳香烃组成,并含有大量S、N、O等杂原子化合物。由于在FCC汽油前脱臭过程中,其中的二烯烃生成了一些低聚物,而在加氢反应过程中,这些低聚物在铁的硫化物及热的作用下迅速生成高聚物而结焦。

The structure and composition of the coke depositing on the catalyst bed of FCC gasoline selective hydrodesulfurization were analyzed by means of SEM, XRD, FT IR, XPS and so on. The mechanism of the coke formation was discussed. The results indicated that the coke had a loosely tufted appearance, consisting of amorphous carbons produced by high polymerization of olefin and aromatics containing a lot of S, N and O atoms, which wrapped around iron sulfide. Due to the oligomers generated from the active olefins and dienes in the pre-deodorization process of FCC gasoline, and these oligomers were converted into polymer immediately in the present of iron sulfide and heat in the later hydrodesulfurization process, the coke directly formed in the catalyst bed of FCC gasoline selective hydrodesulfurization unit.