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Study of the selectivity in FCC naphtha hydrotreating by modifying the acid–base balance of CoMo/γ-Al2O3 catalysts

Paper ID Volume ID Publish Year Pages File Format Full-Text
41524 45892 2010 12 PDF Available
Title
Study of the selectivity in FCC naphtha hydrotreating by modifying the acid–base balance of CoMo/γ-Al2O3 catalysts
Abstract

CoMo catalysts supported on a commercial γ-Al2O3 modified with B, Na or K were prepared in order to analyze the effect of acid–base characteristics on the FCC naphtha hydrotreatment. Catalysts were characterized by NH3 TPD, IR of pre-adsorbed pyridine and CO2, XPS, Raman, and XRD. In general, with either boron or alkaline metal modification the HDS/HYDO selectivity did not significantly improve. However, it is remarkable that when the alumina was modified to be either more acidic (B) or more basic (K, Na), improvements in the ratio between the HDS and the conversion of the internal branched olefin as well as in the ratio double-bond isomerization to HYD of linear olefins were observed. For both modifications, this fact was related to the promotion of the double-bond isomerization reaction from external to internal positions. For alkaline-doped catalysts, it was found that the double-bond isomerization was related to the existence of basic sites. For the boron, there is a range of boria content (2–3 wt.%) where the double-bond isomerization was promoted selectively over the cracking and alkylation reactions because only weak Brönsted acid sites are present. Additionally, both modifications (Boron or alkaline metals) of alumina led to a decrease in the HDS activity, which was found to be related to changes in the distribution of Co and Mo species in the oxide state. Alkaline metal introduction led to the formation of alkaline metal molybdates, whereas boron introduction increased the proportion of octahedral polymeric Mo species, consequently, decreasing the dispersion of the Mo phase.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (75 K)Download as PowerPoint slideResearch highlights▶ CoMo/γ-Al2O3 catalysts were modified with the introduction of a dopant (B, Na or K). ▶ Dopants influence the acid–base balance and the Co and Mo oxide species distribution. ▶ Double-bond isomerization reaction from terminal to internal positions was promoted. ▶ Improvements in the selectivity HDS/HYDO were related to double-bond isomerization. ▶ HDS activity reductions were related to Co and Mo oxide species distribution.

Keywords
FCC naphtha; CoMo; HDS/HYDO selectivity; Acid–base balance; Double-bond isomerization
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Study of the selectivity in FCC naphtha hydrotreating by modifying the acid–base balance of CoMo/γ-Al2O3 catalysts
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 390, Issues 1–2, 20 December 2010, Pages 59–70
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us