Enhanced Fischer-Tropsch activity in ammonium nitrate pretreated cobalt-silica catalyst

Abstract

Reducibility is a key factor when controlling the Fischer-Tropsch (F-T) activity of a cobalt catalyst. We have demonstrated on a cobalt-silica system that by conducting a relatively simple pretreatment step on the SiO2 support with ammonium nitrate can significantly improve reducibility of the catalyst, and thus enhancing the F-T activity which is comparable to more commonly performed, and more costly methods involving noble metal-modification to promote reduction of cobalt. Through catalyst preparation, the Co particle size effect on F-T performance was excluded, and an increase of more than three times higher initial TOF (turnover frequency) for CO conversion is disclosed. Moreover, NH4NO3 acts as a “cleaner”, allowing the activated sites to be available for CO2 formation.