The promotion and poisoning of the hydrodesulfurization of thiophene by phosphate

Conference · Fri Feb 28 23:00:00 EST 1986 · Am. Chem. Soc., Div. Pet. Chem., Prepr.; (United States)

OSTI ID:5458346

Vissers, J P.R.; Bouwens, S M.A.M.; deBeer, V H.J.; Prins, R

It was recognized in the past that phosphate may act as a promoter for hydrodesulfurization (HDS), hydrodenitrogenation and hydrodemetallization reactions. Moreover, phosphorus also may provide increased increased strength and heat stability to the alumina support. Originally, phosphoric acid was added to increase the solubility of the precursor metal salt in the impregnation solutions, the advantage being that with a single impregnation step, catalysts can be prepared with metal compositions common for industrial applications. Hence, the promotion effect of phosphate on the HDS activity of alumina-supported catalysts was explained in terms of a more uniform dispersion of the metal compounds on the support surface. In case the phosphate was incorporated into the alumina support prior to a conventional impregnation with a metal salt solution, the observed promotion effect is more difficult to explain. In this respect, it was suggested that the function of phosphate is to inhibit the formation of catalytically inactive nickel (cobalt) aluminate, or to affect the repartition of the molybdenum phase in the catalysts. In striking contradiction to these results, it was demonstrated that phosphate in carbon-supported molybdenum-based HDS catalysts should be regarded as a poison, able to drastically lower the HDS activity of the catalysts. This dual character of phosphorus is very intriguing, the more so because the chemistry by which it acts as a promoter on one hand and as a poison on the other hand, has not been firmly established. The present study aims to shed more light on this problem by evaluating the properties of phosphate containing, activated carbon-supported Mo catalysts. A series of catalysts samples with varying phosphate content and nearly constant Mo content was prepared and tested for their thiophene HDS activity, X-ray photoelectron spectroscopy, /sup 31/P solid state NMR and dynamic oxygen chemisorption were used to characterize the catalysts.

• Research Organization: Lab. for Inorganic Chemistry and Catalysis, Eindhoven Univ. of Technology, P.O. Box 513, 5600 MB Eindhoven
• OSTI ID: 5458346
• Report Number(s): CONF-860425-
• Journal Information: Am. Chem. Soc., Div. Pet. Chem., Prepr.; (United States), Journal Name: Am. Chem. Soc., Div. Pet. Chem., Prepr.; (United States) Vol. 31:1; ISSN ACPCA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ACTIVATED CARBON
ADSORBENTS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CARBON
CATALYST SUPPORTS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL COMPOSITION
CHEMICAL REACTIONS
CHEMISORPTION
COBALT
DEMETALLIZATION
DENITRIFICATION
DESULFURIZATION
ELEMENTS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
HYDROGENATION
IMPREGNATION
INHIBITION
INORGANIC ACIDS
MAGNETIC RESONANCE
METALS
MOLYBDENUM
NICKEL
NONMETALS
NUCLEAR MAGNETIC RESONANCE
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHOSPHATES
PHOSPHORIC ACID
PHOSPHORUS
PHOSPHORUS COMPOUNDS
RESONANCE
SEPARATION PROCESSES
SOLUBILITY
SORPTION
SPECTROSCOPY
STABILITY
TESTING
THIOPHENE
TRANSITION ELEMENTS
X-RAY SPECTROSCOPY