Sylvain Hantzer

New synthesis and uses of high-specific-surface SiC as a catalytic support that is chemically inert and has high thermal resistance

A new method for preparation of high-specific-surface (60–400 m2/g) SiC is described. This method consists of the attack of high-specific-surface activated carbon by SiO vapor generated by the high-temperature reaction of Si and SiO2. The high specific surface is probably due both to the low temperature of the reaction between SiO and C and to the presence of a stable carbon skeleton. Before reaction, the carbon can be doped with different additives to improve the surface interaction between SiC and the impregnated active phase. The action of uranium doping is also shown. SEM, XRD, thermogravimetry, TPR, XPS, BET, and porosimetry have been used to characterize the supports and the catalysts. Test reactions (hydrodesulfurization by CoMo) are also reported.

Hydrotreatment catalyst poisoning by vanadium and nickel porphyrin: ESR and NMR

Abstract Hydrotreatment catalysts (NiMo) are poisoned by vanadyl and nickel porphyrins. Their HDS activities are correlated to the nature and the structure of the poison, analyzed by EPR, Metal Solid NMR and High Resolution TPR on the active sulphided surfaces.

Hydrodesulfurization (HDS) poisoning by vanadium compounds: EPR and metal solid NMR analysis

The HDS activity of a commercial NiMo catalyst has been followed versus the amount of vanadium added to it, either by an oxidic procedure before the sulfidation step or by a sulfided route, using a highly soluble vanadyl porphyrin simulating the industrial process on the presulfided catalyst. An oxidative regeneration followed by a resulfidation transformed these porphyrinpoisoned catalysts into the oxidic preparation family. At the same time, Metal Solid NMR and EPR spectroscopies have been used to characterize the nature of the vanadium deposit. The very strong deactivation in the sulfided phase is due only to vanadyl species, well characterized by EPR; while the deactivation of the catalysts, where vanadium has been oxidized in V2O5, is due to vanadium Sulfides, as is shown by NMR.

Poisoning of Hydrodesulfurization Catalysts by Vanadium

Abstract The HDS activity of a commercial NiMo catalyst has been followed versus the amount of vanadium added to it, either by an oxidic procedure or by a sulfided route, using a highly soluble vanadyl porphyrin, simulating the industrial process. At the same time, Metal Solid NMR and EPR spectroscopies have been used to characterize the nature of the vanadium deposit.