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Effect of iron and calcium over USY coke formation

Paper ID Volume ID Publish Year Pages File Format Full-Text
43280 45961 2008 7 PDF Available
Title
Effect of iron and calcium over USY coke formation
Abstract

Although several studies discuss the effect of metals on the FCC process, very few focus on those caused specifically by Fe and Ca. Within this work, different zeolite samples were prepared by impregnating nickel and vanadium on an ultra stable Y zeolite (USY), previously exchanged with iron and calcium. The samples were used in three model reactions: cyclohexane transformation at 300 °C, n-hexane cracking (500 °C) and ethane hydrogenolysis. The first reaction aimed at studying coke formation tendencies. The second reaction allowed an indirect measure of catalyst acidities and ethane hydrogenolysis (which was used to discuss nickel particle formation). Bifunctional catalysts presented a higher tendency to form coke compared to pure USY. This effect was much more pronounced in the presence of Ni and V. Bimetallic catalyst NiVUSY forms relatively low amounts of coke when compared to monometallic catalysts, and exhibits a higher olefin to paraffin ratio. The addition of Fe or Ca to the bimetallic catalyst largely reduces coke formation and increases the olefin to paraffin ratio. When compared to the NiVUSY catalyst, the reduction temperature decreases 20 and 50 °C for FeNiVUSY and CaNiVUSY catalyst, respectively. In addition ethane hydrogenolysis reveals nickel activity only for FeNiVUSY catalyst. These results support that Fe and Ca affect nickel and vanadium chemical environment and probably their distribution on the catalyst surface.

Graphical abstractDifferent bifunctional catalysts were used in three model reactions: cyclohexane transformation, n-hexane cracking and ethane hydrogenolysis. Bimetallic catalyst NiVUSY forms relatively low amounts of coke when compared to monometallic catalysts, and exhibits a higher olefin to paraffin ratio. The addition of Fe or Ca to the bimetallic catalyst largely reduces coke formation and increases the olefin to paraffin ratio.Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Nickel; Vanadium; Iron; Calcium; USY; Coke; FCC
First Page Preview
Effect of iron and calcium over USY coke formation
Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 339, Issue 1, 15 April 2008, Pages 61–67
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis