1. STEM study of Mn/Co/TiO2 Fischer-Tropsch Catalysts
Robert F. Klie, Department of Physics, University of Illinois at Chicago, Chicago, IL
Selective Mn adsorption: We synthesized the Mn-promoted Co catalyst on TiO2 support using strong electro-static adsorption (SEA) to selectively deposit Mn on Co, but not on the TiO2 support. Our XPS data confirms the complete coverage of Co with Mn. However, after reduction some of the Co surface becomes exposed again.
Our Z-contrast imaging and EELS analysis shows that Mn selectively covers the Co surface after Mn deposition, and not the TiO2 support. Co Mn
TiO2
After calcination, reduction in H2(2 h):
As prepared:
After reduction in H2 for 2 hours at 350° C, we find a reduction in the
Co valence, indicating that the Co3O4 particles have been reduced to CoO1-x.
The Mn distribution on the Co particle surface has changed
This work is done by Nanoscale Physics Group, UIC,
It is funded by Petroleum Research Fund of American Chemical Society 2)
significantly. The Mn-particles do not cover the entire Co surface, but form distinct nano-particles. Still no Mn is found in the TiO2 support.
Also, we did not find any sign of metallic Co on the particle surface, even after in-situ reduction at 350° C for 2 hours. Our next goal will be to analyze the effects of Mn on the Co/TiO2 interface and correlate the changes in the Co valence to the catalyst’s performance.