Toward the chemical conversion of CO2: understanding the interaction of CO2 with model metal/metal-oxide systems
EMSL Project ID
45590
Abstract
Environmental concerns about the increasing level of atmospheric CO2, a major greenhouse gas component, have prompted research efforts in two major directions: sequestration and chemical conversion of CO2. In both processes CO2 needs to be captured first by a solid (or liquid) material, and then either stored as carbonate or chemically converted to organic compounds that can be further processed to provide fuels, or other value added chemicals. The interaction of CO2 with metals has been studied in some details, and it was established that without promoters (e.g. alkalis) CO2 adsorbed weakly on metal surfaces. The strength of adsorption can significantly be enhanced by promoters of very low electronegativity. In these cases CO2 can accept an electron from the metal surface and form a CO2- radical ion. The thus formed radical ion is much more susceptible for chemical reactions than the electroneutral CO2 molecule. Even less effort has been directed toward the understanding of the activation of CO2 by metal-oxides. Reforming of CO2 (by H2 or hydrocarbons) has been studied on some transition metal oxide catalysts (Fe, Co, Ni), and recently its photoreduction was investigated on TiO2- and ZnO-based photocatalysts. Oxides one may consider as potential CO2 activation catalysts are the ones with electron rich defect centers, that can be produced with relative ease. These electron-rich centers may interact with CO2 by donating an electron, and forming CO2- radical ions (similarly to the case discussed above for the alkali-promoted metal surfaces). This electron transfer to the CO2 molecule may occur directly (i.e., from the oxide to the defect site-adsorbed CO2), or indirectly, when a metal nanopraticle anchored to the reduced metal-oxide center serves as active site for the electron transfer. In addition, by introducing metal centers onto the surface of the reducible oxide we can provide the reduction function to the system that is needed for the further conversion of the activated ion radical. The proposed work will fovus on two main research objectives: 1. Understanding the activation of CO2 on reducible metal oxide oxide films/nanoparticles supported on metal single crystals, and 2. the activation of CO2 on on subnanometer sized metal particles (atomically distributed metals) on different high surface area support materials.
Project Details
Project type
Exploratory Research
Start Date
2011-10-01
End Date
2012-10-07
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Kwak JH, L Kovarik, and J Szanyi. 2013. "Heterogeneous Catalysis on Atomically Dispersed Supported Metals: CO2 Reduction on Multifunctional Pd Catalysts." ACS Catalysis 3(9):2094-2100. doi:10.1021/cs4001392
Szanyi J, M Daturi, G Clet, DR Baer, and CHF Peden. 2012. "Well-studied Cu-BTC still serves surprises: evidence for facile Cu2+/Cu+ interchange." Physical Chemistry Chemical Physics. PCCP 14(13):4383–4390. doi:10.1039/c2cp23708c