Tricia D. Smurthwaite

Interaction of lithium hydride and ammonia borane in THF

The two-step reaction between LiH and NH(3)BH(3) in THF leads to the production of more than 14 wt% of hydrogen at 40 degrees C.

Low viscosity alkanolguanidine and alkanolamidine liquids for CO2 capture

Global carbon dioxide (CO2) emission is expected to increase tremendously with the shift to coal-powered plants for energy generation. Capture and sequestration of CO2 are needed to mitigate environmental effects. Solvents currently used for this are the energy-intensive aqueous amines. Here we present 10 advanced solvents called alkanolguanidines and alkanolamidines that are potentially energy-efficient CO2-capture solvents. These solvents were synthesized in 1–3 steps from commercially available materials. One alkanolamidine derived from a 1,8-diazabicyclo[5.4.0]-undec-7-ene (DBU) base core has a low vapor pressure and a high viscosity, resulting in low CO2 uptake capacity at standard temperature and pressure (STP). Three imidazoline base derived alkanolamidines were non-viscous but do not bind CO2 at STP, however, under mild pressure they effectively capture 7–10 wt%, making them suitable for high-pressure CO2 capture. Six novel alkanolguanidine molecules have low vapor pressure and low viscosity (<10 cP) which enable high CO2 uptake at STP. These compounds bind CO2 chemically via the alcohol moiety forming zwitterionic guanidinium and amidinium alkylcarbonate ionic liquids. These materials can be regenerated thermally by heating the alkylcarbonate to 75 °C. CO2 binding capacities of up to 12 wt% were achieved using several of these compounds at STP. Through this study we found that alkanolguanidines have low viscosity, are non-volatile, have high CO2 uptake at STP and are tolerant to water; thus we selected one compound for physical property testing.

Electronic and Chemical State of Aluminum from the Single- (K) and Double-Electron Excitation (KLII&III, KLI) X-ray Absorption Near-Edge Spectra of α-Alumina, Sodium Aluminate, Aqueous Al(3+)·(H2O)6, and Aqueous Al(OH)4(-).

We probe, at high energy resolution, the double electron excitation (KLII&II) X-ray absorption region that lies approximately 115 eV above the main Al K-edge (1566 eV) of α-alumina and sodium aluminate. The two solid standards, α-alumina (octahedral) and sodium aluminate (tetrahedral), are compared to aqueous species that have the same Al coordination symmetries, Al(3+)·6H2O (octahedral) and Al(OH)4(-) (tetrahedral). For the octahedral species, the edge height of the KLII&III-edge is approximately 10% of the main K-edge; however, the edge height is much weaker (3% of K-edge height) for Al species with tetrahedral symmetry. For the α-alumina and aqueous Al(3+)·6H2O the KLII&III spectra contain white line features and extended absorption fine structure (EXAFS) that mimics the K-edge spectra. The KLII&III-edge feature interferes with an important region in the EXAFS spectra of the crystalline and aqueous standards. The K-edge spectra and K-edge energy positions are predicted using time-dependent density functional theory (TDDFT). The TDDFT calculations for the K-edge X-ray absorption near-edge spectra (XANES) reproduce the observed transitions in the experimental spectra of the four Al species. The KLII&II and KLI onsets and their corresponding chemical shifts for the four standards are estimated using the delta self-consistent field (ΔSCF) method.