We have studied titania-supported 3-amino-1-propanol (3AP) and monoethanolamine (MEA) as a potential CO2 capture material using synchrotron-based ambient pressure X-ray photoelectron spectroscopy (AP-XPS), scanning tunneling microscopy (STM), and ab-initio calcualtions. STM and AP-XPS of C(1s) and N(1s) core levels demonstrate the successful adsorption of 3AP molecules along the Ti rows of the rutile TiO2(110) surface, a process that self-terminates with the completion of the 1st layer at 300 K. Calculations give an optimized structure in which both terminal groups of 3AP form donor-acceptor bonds with 5-fold coordinated surface Ti atoms. In stark contrast to the facile CO2 capture by 3AP/TiO2(110), MEA on the same support is shown to be inactive towards CO2 capture. Calculations show that the vanishing activity is due to strong binding of the amine functional group in MEA to surface Ti atoms of the support, which is facilitated by a close correspondence between the separation of reactive end groups of the molecule and the binding sites of the substrate. Exposing 3AP/TiO2(110) to near-ambient pressures of CO2 (up to 2 Torr) gives rise to additional C(1s) peaks, which are attributed to captured CO2 and gas phase CO2 respectively. The peak attributed to captured CO2 is consistent with a carbamate (-NHCOO) species on the surface, but its lineshape is consistent with a minority contribution from a carbonate species as well. Our results illustrate the importance of structure-property relationships between the adsorbed amine capture species and the support, which govern amine-based solid-supported CO2 capture. This talk will discuss the broader implications of our studies on this model system towards solid-state CO2 capture.

Key structure-property relationships in CO<sub>?2</sub>? capture by supported alkanolamines

247th National Meeting (2014)

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Key structure-property relationships in CO?2? capture by supported alkanolamines

Key structure-property relationships in CO_?2? capture by supported alkanolamines