Pretreatment of a new lanthanum molybdenum sulfide (LaMoS) hydrodesulfurization (HSD) catalyst in flowing H2 has been investigated. Following pretreatment up to 800°C, the catalyst surface area decreased from 175 to 11 m2/g; the average pore diameter increased due to the loss of pore diameters smaller than 100 Å. TPD characterization of the as-prepared LaMoS was used to monitor the evolution of solvents and adsorbed materials up to 800°C. The Mo oxidation state was examined after various pretreatment procedures using X-ray photoelectron spectroscopy (XPS) and temperature-programmed reduction (TPR). Following temperature-programmed desorption (TPD), two types of surface oxygen were detected which could be reduced at 250°C and 950°C by a flow of 10% H2 in N2. Transformation of the amorphous LaMoS to the corresponding crystalline Chevrel phase [La(Mo6S8)] was detected at 1000°C using TPR and x-ray diffraction (XRD). (C) 2000 Elsevier Science B.V.
- Amorphous ternary molybdenum sulfides
- Chevrel phases
- H pretreatment
- Metal sulfide clusters
ASJC Scopus subject areas
- Process Chemistry and Technology
- Physical and Theoretical Chemistry