THE IMPORTANCE OF SULFIDING TEMPERATURE OF A HDS CATALYST IN THE CONVERSION OF UNSATURATES IN A BENZENE, TOLUENE AND XYLENE (BTX) FEED

The effect of changing the sulfiding temperature (T-s) of a Go-Mo sulf ide/gamma-Al2O3 hydrogenation catalyst in the range 200 degrees C to 4 50 degrees C, has been studied by the hydrogenation of cyclopentadiene , styrene alphamethylstyrene and indene impurities in a commercial pla nt feed at 200 degrees C in a laboratory reactor. Transmission electro n microscopy (TEM) was used to examine the morphology and structure of the catalyst and X-ray photoelectron spectroscopy (XPS) to ascertain the oxidation states of the Co and Mo. The performance of the catalyst peaked for T-s around 400 degrees C. For T-s < 300 degrees C, the pre sence of catalyst material on the substrate could be deduced with TEM only from the grainy appearance of the support, but for higher T-s, Mo S2 was seen arranged with its basal planes normal to the support. XPS revealed increased concentrations of Mo4+, as MoS2, with rising T-s. T he Co 2p(3/2)-S 2p binding energy splitting increased from 616.0 +/- 0 .2 eV at T-s = 200 degrees C to 617.3 +/- 0.1 eV at T-s = 350 degrees C, indicating that the Co increasingly decorated the edges of the MoS2 . (C) 1998 Elsevier Science B.V.