Attempts To Improve the Product Slate Quality: Influence of Coke-on-Catalyst Content

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• 作者：Avelino Corma ; Francisco V. Melo ; Laurent Sauvanaud
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2007
• 出版时间：June 6, 2007
• 年：2007
• 卷：46
• 期：12
• 页码：4100 - 4109
• 全文大小：684K
• 年卷期：v.46,no.12(June 6, 2007)
• ISSN：1520-5045

文摘

Several catalysts with increasing initial coke content were processed in the Microdowner unit in order toassess the activity and selectivity of coked catalyst. Tests were carried out at both constant operating conditionsand changing catalyst-to-oil ratio to maintain conversion. It was found that coke on regenerated catalyst(CRC) has very little influence on the main product selectivity, while some effect on product quality wasdetected. CRC changed the hydrogen transfer to cracking relative rate as it lowered site density, resulting ina dramatic increase in the isobutene-to-isobutane ratio. Gasoline was more olefinic and less paraffinic, whilesulfur content increased. LCO yield increased slightly, producing a distillate with better quality (fewer aromaticsand more paraffins). When ZSM5 is used, it has been observed that propylene selectivity increases at constantconversion at a rate around 1 point of propylene per percent coke on catalyst. Apart from the cracking selectivitychanges in the riser, the significant increase in catalyst circulation that is necessary to maintain conversionmay have some beneficial effects for feed vaporization and reduced thermal cracking at the injection point.