Cobalt-support compound formation in titania-supported cobalt catalysts

Abstract

Co-support compound formation (Co-SCF) in Co/TiO[subscript 2] was found during standard reduction resulting in a lower reducibility of the catalyst. The compound formed is considered to be non-reducible at temperatures < 800 ํC during TPR and different from CoTiO[subscript 3]. The characteristics of Co-SCF were investigated using BET surface area, XRD, H[subscript 2] chemisorption, Raman spectroscopy, SEM/EDX and TPR. In addition, effects of crystalline form of the TiO[subscript 2] supports were also studied. A comparative study of titania supports used between the pure anatase phase (T1) and mixed phase; anatase and rutile (T2) was investigated. The results indicated the differences in titania support phases can affect the catalyst performance especially in the overall activity and stability. It was found that the overall activity and the stability in CO hydrogenation reaction of the Co/T2 catalysts was higher than that of Co/T1 catalysts. This is probably because rutile phase may help promoting the activity of the Co/TiO[subscript 2] catalysts and inhibiting Co-SCF. The addition of Ru promoter was found to enhance both reducibilities and the overall activities. When Ru promoter was present, the formation of Co-SCF decreased significantly due to hydrogen spillover effect.