(669g) Chemical Transient Kinetic Studies on Co-Re Based Catalysts for CO Hydrogenation

Chemical transient kinetic studies on Co-Re based catalysts for CO hydrogenation

Nitin Kumar¹, Faisal Alotaibi,² Zi Wang¹ and J.J. Spivey¹

¹Department of Chemical Engineering, Louisiana State University, Baton Rouge, LA 70803, USA

²KACST, Petrochemical Technology Research Center, Riyadh, 11442, Saudi Arabia

Abstract

Although CO hydrogenation via the Fischer-Tropsch process has been well studied, there are still questions about the specific reaction mechanism. In this work, CO hydrogenation is studied over a series of 10%cobalt-4%rhenium catalysts using the chemical transient kinetic method. A series of 4 cobalt-rhenium based catalysts are used for this study. The basis of the study is to see the effect of precursoes, effect of Mn addition as a promoter, and effect of support modification by Sr and Zr on the mechanism of CO hydrogenation and product formation.

The experiments are carried out over a reduced catalyst under constant flow of H₂, while switching CO with helium till the steady state is reached for each switching operation. The experiments are carried out at atmospheric pressure and higher temperatures, and products are quantified using an in-line quadrupole mass spectrometer. Although F-T pressures are typically 30 bar, the conditions investigated here can be used to probe the surface so that the reaction products are gases and can be quantified.

The results show the mean residence times for different species on these catalysts and their surface population. These experiments are useful in providing the information about surface composition and how it changes with time under the reaction conditions. Different gaseous species are identified and quantified by the mass spectrometer and their relative times indicate the formation and desorption of the respective species on the surface of the catalyst. This is helpful in understanding the mechanism of the reaction over these catalysts.