| AVS 64th International Symposium & Exhibition | |
| Fundamental Discoveries in Heterogeneous Catalysis Focus Topic | Thursday Sessions |
| Session HC-ThP |
| Session: | Fundamental Discoveries in Heterogeneous Catalysis Poster Session |
| Presenter: | Karthikeyan K. Ramasamy, Pacific Northwest National Laboratory |
| Authors: | K.K. Ramasamy, Pacific Northwest National Laboratory M. Guo, Pacific Northwest National Laboratory M. Gray, Pacific Northwest National Laboratory S. Subramaniam, Pacific Northwest National Laboratory A. Karakoti, Ahmedabad University, India V. Murugesan, Pacific Northwest National Laboratory V. Shutthanandan, Pacific Northwest National Laboratory S. Thevuthasan, Pacific Northwest National Laboratory |
| Correspondent: | Click to Email |
Unique physical and chemical properties of layered double hydroxide, hydrotalcite (HT) (M2+1−xM3+x(OH)2]x+An−x/n·mH2O), derived materials have been used for selective and efficient transformations of organic compounds to higher value products. The catalytic properties of the HT derived mixed oxide material are a function of the morphology, local structure and oxidation state of the participating cations. In this work the effect of addition of copper ions on the catalytic properties of MgAl HT derived materials were studied for selective conversion of ethanol to higher alcohols. The ethanol to higher alcohol conversion goes thru a series of complex intermediate steps. The addition of copper is expected to promote the catalytic dehydrogenation of alcohols to aldehydes which is the first step in the complex cascade reaction and considered as the rate determining step in the overall chemistry. Various concentration of copper loading were attempted from 0 wt% to 6 wt % using different synthesis strategies in an attempt to achieve a homogenous dispersion of copper in the MgAl matrix. The selectivity and efficiency of copper substituted catalysts were analyzed by conversion of ethanol to higher alcohols in an indigenously designed plug flow reactor. Resulting physical and chemical changes in copper substituted catalysts were studied before and after the catalytic reaction using high resolution transmission electron microscopy, x-ray diffraction, x-ray absorption, X-ray photoelectron spectroscopy and nuclear magnetic resonance measurements. It was observed that different oxidation states of copper and the extent of dispersion of copper in the HT matrix influences catalytic efficiency and selectivity of the process by promoting various side reactions. Synthesis of copper substituted HT derived mixed oxide catalyst plays a major role in controlling the dispersion of the copper in the matrix. Fundamental challenges in achieving higher copper substitution without observing significant clustering and aggregation effects will be discussed in context of catalytic selectivity and efficiency.