Characterisation and performance of hydrotalcite-derived CoMo sulphide catalysts for selective HDS in the presence of olefin

Hydrotreating catalysts were prepared from CoMgMoAl layered double hydroxides (LDHs) with different Co and Mo contents. Sulphides were characterised by techniques such as X-ray absorption near edge structure spectroscopy, CO adsorption followed by infrared spectroscopy, X-ray diffraction and nitrogen physisorption. The prepared catalysts were tested in the selective hydrotreating of a model feed (thiophene, cyclohexene and n-heptane) under 573 K and 20 bar of H-2, covering a wide range of space velocities (41-439 h(-1)). All the LDH-derived CoMgMoAl sulphides showed larger selectivity for hydrodesulphurisation when compared to industrial catalysts. The characterisation results allowed a relationship between the nature and concentration of sulphide sites and their catalytic functionalities to be established.