Reactivity of several olefins in the HDS of full boiling range FCC gasoline over PtPd/USY
Advancing the chemical engineering fundamentals
Catalysis (T2-13P)
Keywords: FCC gasoline, HDS, olefin hydrogenation, PtPd/USY
Authorities are world-wide forcing the petroleum companies to reduce the sulfur content of fuels below 50, 30 or 10 mg/kg. Desulfurization of FCC gasoline is a key process in the refineries for blending gasoline of ultra low sulfur content. Among the main FCC gasoline sulfur reduction options (pre-treating, in-situ sulfur reduction in the FCC unit by using catalyst additives, post-treating), hydrotreatment of cracked naphtha is still the most preferred method.
Hydrodesulfurization (HDS) on conventional CoMo/Al2O3 catalysts results in significant olefin saturation and high H2 consumption making this process unsuitable for cracked naphtha upgrading. The most preferred way for sulfur reduction is hydrotreatment over special catalysts providing high HDS level and low olefin hydrogenation. In our previous papers we reported that PtPd/USY is applicable for the selective HDS of FCC gasoline containing less than 200 ppm sulfur.
In this work, the reactivity of C4-C6 olefins during the selective HDS of a full boiling range FCC gasoline over PtPd/USY catalyst was studied under various process conditions. The effect of the structure and carbon number of the olefins on their conversion will be discussed in the presentation. It was found, for example, that terminal olefins are partly converted to internal olefins by double bond shift during the hydrotreatment. Conversions of linear cis-olefins were found to be higher those of trans-olefins and the conversion of linear olefins increases with the carbon number.
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Presented Wednesday 19, 13:30 to 15:00, in session Catalysis (T2-13P).
