Deactivation of hydrotreating catalysts: Evolution of coke and active phase

PETR 35

Bertrand Guichard, bertrand.guichard@ifp.fr1, Magalie Roy-Auberger, Magalie.ROY@ifp.fr1, Elodie Devers, elodie.devers@ifp.fr1, and Daniel Schweich, dsw@lobivia.cpe.fr2. (1) Heterogeneous and Catalysis Department, IFP, BP n°3, 69390 Vernaison, France, (2) LGPC, ESCPE –LYON, 43 bd du 11 Novembre 1918, BP. 2077, 69616 Villeurbanne, France
With the strengthening of environmental legislation which requires to produce ultra-low sulfur diesel fuel, some questions arise about catalysts stability. Selected spent catalysts have been characterized in term of physico-chemical properties and tested over model molecules in order to understand deactivation mechanisms. Raman spectroscopy shows a more ordered coke with time-on-stream. Moreover, it appears from TPO and XPS that coke is first deposited over alumina and then over active sites. XPS measurements also highlight a decrease of the promotion ratio with processing time, mainly due to promoter segregation whereas MoS2 slabs size keeps steady (TEM). These observations, linked to residual activities results, led us to propose a three-steps deactivation scheme in which coke localisation, coke nature and promotion ratio are key parameters. Coke is first deposited over alumina; then a graphitization process starts while promoter segregation occurs; finally, coke covers catalytic sites leading to a drastic decrease in catalytic activity.
 

2nd International Symposium on Hydrotreating/Hydrocracking Technologies
8:30 AM-11:50 AM, Monday, 11 September 2006 Palace -- Presidio Room, Oral

Division of Petroleum Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006