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Hierarchically structured porous materials often exhibit advantageous functionality for many applications including catalysts, adsorbents, and filtration systems. In this study, we report a facile approach to achieve hierarchically structured, porous cerium oxide (CeO2) catalyst particles using a templating method based on nanocellulose, a class of renewable, plant-derived nanomaterials. We demonstrate the catalyst performance benefits provided by this templating method in the context of Catalytic Fast Pyrolysis (CFP) which is a promising conversion technology to produce renewable fuel and chemical products from biomass and other types of organic waste. We show that variations in the porous structures imparted by this templating method may be achieved by modifying the content of cellulose nanofibrils, cellulose nanocrystals, and alginate in the templating suspensions. Nitrogen physisorption reveals that nearly 10-fold increases in surface area can be achieved using this method with respect to commercially available cerium oxide powder. Multiscale electron microscopy further verifies that bio-derived templating can alter the morphology of the catalyst nanostructure and tune the distribution of meso- and macro-porosity within the catalyst particles while maintaining CeO2 crystal structure. CFP experiments demonstrate that the templated catalysts display substantially higher activity on a gravimetric basis than their non-templated counterpart, and that variations in the catalyst architecture can impact the distribution of upgraded pyrolysis products. Finally, we demonstrate that the templating method described here may be extended to other materials derived from metal chlorides to achieve 3-dimensional networks of hierarchical porosity.

We have recorded stimulated emission pumping (SEP) spectra of the Ã1A‘ ‘ → 1A‘ system of CHF, which reveal rich detail concerning the rovibronic structure of the 1A‘ state up to ∼7000 cm-1above the vibrationless level. Using several intermediate Ã1A‘ ‘ state levels, we obtained rotationally resolved spectra for 16 of the 33 levels observed in our previous single vibronic level (SVL) emission study (Fan et al., J. Chem. Phys.2005, 123, 014314), in addition to one new level. An anharmonic effective Hamiltonian model poorly reproduces the term energies even with the improved set of data because of the extensive interactions among levels in a given polyad (p) having combinations of 1, 2, 3, which satisfy the relationship p 2123. However, the precise Arotational constants determined from the SEP data were invaluable in clarifying the assignments for these strongly perturbed levels, and the data are well reproduced using a multiresonance effective Hamiltonian model. The derived vibrational parameters are in good agreement with high level ab initiocalculations. The experimental frequencies were combined with those of CDF to derive a harmonic force field and average (rz, %@mt;sys@%%@ital@%r%@rsf@%%@mh;1q@%%@sx@%%@ital@%e%@rsf@%%@be@%%@ital@%z%@rsf@%%@sxx@%%@mx@%) structures for the ground state. [ABSTRACT FROM AUTHOR]

Building upon our recent observation of the gas-phase electronic spectrum of the iodomethyl cation (CH2I), we report an extensive study of the electronic spectroscopy of CH2Iand its deuterated isotopomers CHDIand CD2Iusing a combination of fluorescence excitation and single vibronic level (SVL) emission spectroscopies. The spectra were measured in the gas phase under jet-cooled conditions using a pulsed discharge source. Fluorescence excitation spectra reveal a dominant progression in 3(C−I stretch), the frequency of which is markedly smaller in the upper state. Rotational analysis shows that, while the Aconstant is similar in the two states, the excited state has significantly smaller Band Cconstants. These results indicate a lengthening of the C−I bond upon electronic excitation, consistent with calculations which show that this transition is analogous to the well-known − transition in the isoelectronic substituted formaldehydes. SVL emission spectra show progressions involving four of the six vibrational modes; only the C−H(D) stretching modes remain unobserved. The vibrational parameters determined from a Dunham expansion fit of the ground state vibrational term energies are in excellent agreement with the predictions of density functional theory (DFT) calculations. A normal-mode analysis was completed to derive a harmonic force field for the ground state, where resonance delocalization of the positive charge leads to partial double bond character, H2C−I ↔ H2CI, giving rise to a C−I stretching frequency significantly larger than that of the iodomethyl radical. [ABSTRACT FROM AUTHOR]