Effect of metal—organic compounds on thiophene hydrodesulphurization over sulphided Co(Ni)Mo/Al2O3 catalysts

Deactivation effects in hydrodesulphurization of thiophene in a pulse reactor over cobalt and nickel promoted Mo/Al₂O₃ catalysts and with vanadium and nickel naphthenate additions were studied. The catalysts were sulphided with CS₂ in hydrogen, and an initial reduction in hydrogen was found to be unnecessary. In the hydrodesulphurization of thiophene smaller changes are observed. A fast initial coking effect is indicated. After regeneration, strongly bonded sulphate species are obtained. Deactivation by the addition of nickel or vanadium naphthenate in a low concentration works similarly. At higher doses, vanadium naphthenate affects both catalysts more strongly than nickel naphthenate. X-ray photoelectron spectroscopy indicates that the metal compounds deposit to a higher extent at the catalyst particles' exterior than at interior surfaces at high levels of additions.