Glycothermal synthesis of nanocrystalline zirconia and their applications as cobalt catalyst supports

Nanocrystalline zirconia have been prepared by the glycothermal method with two different glycols (1,4-butanediol and 1,5-pentanediol) and employed as the support for cobalt catalysts. Commercial zirconia supported cobalt catalyst was also prepared and used as a reference material. The glycothermal-derived zirconia possesses large surface areas with crystallite sizes of 3-4 nm. The catalytic activities for CO hydrogenation of the glycothermal-derived zirconia supported cobalt catalysts were found to be much higher than that of the commercial zirconia supported one. However, the cobalt catalysts supported on zirconia prepared in 1,4-butanediol with lower amount of Zr content in the starting solution exhibited higher activities than the ones supported on zirconia prepared in 1,5-pentanediol. The results suggest that the different crystallization mechanism occurred in the two glycols may affect the amount of crystal defects produced in the corresponding zirconia. As shown by TPR profiles, lower metal-support interaction was observed for the catalysts supported on the zirconia formed via solid-state reaction in 1,4-butanediol (more defects). Consequently, higher active surface cobalt was available for H2 chemisorption and CO hydrogenation reaction.