TPR and TPD studies of effects of Cu and Ca promotion on Fe-Zn-based Fischer-Tropsch catalysts.

Temperature-programmed reduction (TPR) and temperature-programmed desorption (TPD) were used to study the effects of Cu and Ca promotion on Fe-Zn-based Fischer-Tropsch catalysts. The reduction temperature for FeO → FeO was unaffected by Ca addition but decreased when promoted with Cu. Fe-Zn promoted with Cu and Ca showed even much lower reduction temperature for FeO → FeO. Ca promotion enhances carburization and increases surface acidity and basicity of the Fe-Zn oxide precursor. While Cu inhibits carburization and decreases the surface acidity and basicity of the Fe-Zn oxide precursor. The implications of these effects on the application of catalysts for FT are discussed. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]