The importance of sulfiding temperature of a HDS catalyst in the conversion of unsaturates in a benzene, toluene and xylene (BTX) feed

Abstract

The effect of changing the sulfiding temperature ( T s) of a Co–Mo sulfide/ γ-Al 2O 3 hydrogenation catalyst in the range 200°C to 450°C, has been studied by the hydrogenation of cyclopentadiene, styrene alphamethylstyrene and indene impurities in a commercial plant feed at 200°C in a laboratory reactor. Transmission electron 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°C. For T s<300°C, the presence of catalyst material on the substrate could be deduced with TEM only from the grainy appearance of the support, but for higher T s, MoS 2 was seen arranged with its basal planes normal to the support. XPS revealed increased concentrations of Mo 4+, as MoS 2, with rising T s. The Co 2 p 3/2–S 2 p binding energy splitting increased from 616.0±0.2 eV at T s=200°C to 617.3±0.1 eV at T s=350°C, indicating that the Co increasingly decorated the edges of the MoS 2.