Effect of defected zirconia support on catalytic activity of carbonmonoxide hydrogenation

Abstract

In this study, the modified Pechini method has been used to prepare alumina-zirconia mixed oxides varied in a range of 25-75% by mole of alumina in zirconia. To compare with the mixed oxides, pure alumina and pure zirconia were also prepared by the same method. Physicochemical properties of all samples were investigated and elimination of 2-propanol was used to evaluate the catalytic performance of solid surface. The modified Pechini preparation resulted in poor acid-base strength of alumina surface resulting in high acetone selectivity where imperfect crystal structure of the tetragonal zirconia favoured high propylene production in 2-propanol elimination employed as cobalt catalyst support for CO hydrogenation. Moreover, zirconia with low alumina content (0.5-1 mole% Al) were also prepared and tested as support. When zirconia with low Al content supported Co catalysts increased 30% compared to the ones supported on pure zirconia or pure alumina suggesting the modification of zirconia by alumina resulting in higher Co dispersion. However, when supports with high alumina contents (40-75 mole% Al) were used, low Co dispersion and poor catalytic performance were found. It is likely that cobalt formed metal-support compounds with amorphous phase of these mixed oxides. Finally, tetragonal zirconia with low content of another elements (0.5-1 mole%), i.e. Y or Si was introduced to be Co catalyst support, however the catalytic performances and stabilities of these supports exhibited fairly lower than that of zirconia with low Al content.