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Title: Ordered Mesoporous Metal Carbides with Enhanced Anisole Hydrodeoxygenation Selectivity

Authors:
; ; ; ; ;  [1];  [2];  [2]
  1. Columbia
  2. (
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
UNIVERSITY
OSTI Identifier:
1255295
Resource Type:
Journal Article
Resource Relation:
Journal Name: ACS Catalysis; Journal Volume: 6; Journal Issue: 6
Country of Publication:
United States
Language:
ENGLISH

Citation Formats

Lu, Qi, Chen, Cha-Jung, Luc, Wesley, Chen, Jingguang G., Bhan, Aditya, Jiao, Feng, Delaware), and UMM). Ordered Mesoporous Metal Carbides with Enhanced Anisole Hydrodeoxygenation Selectivity. United States: N. p., 2016. Web. doi:10.1021/acscatal.6b00303.
Lu, Qi, Chen, Cha-Jung, Luc, Wesley, Chen, Jingguang G., Bhan, Aditya, Jiao, Feng, Delaware), & UMM). Ordered Mesoporous Metal Carbides with Enhanced Anisole Hydrodeoxygenation Selectivity. United States. doi:10.1021/acscatal.6b00303.
Lu, Qi, Chen, Cha-Jung, Luc, Wesley, Chen, Jingguang G., Bhan, Aditya, Jiao, Feng, Delaware), and UMM). 2016. "Ordered Mesoporous Metal Carbides with Enhanced Anisole Hydrodeoxygenation Selectivity". United States. doi:10.1021/acscatal.6b00303.
@article{osti_1255295,
title = {Ordered Mesoporous Metal Carbides with Enhanced Anisole Hydrodeoxygenation Selectivity},
author = {Lu, Qi and Chen, Cha-Jung and Luc, Wesley and Chen, Jingguang G. and Bhan, Aditya and Jiao, Feng and Delaware) and UMM)},
abstractNote = {},
doi = {10.1021/acscatal.6b00303},
journal = {ACS Catalysis},
number = 6,
volume = 6,
place = {United States},
year = 2016,
month = 6
}
  • No abstract prepared.
  • The authors present optimized geometries and binding energies for alkali metal cation complexes with anisole (methoxybenzene). Results are obtained for Li{sup +} through Cs{sup +} at the RHF/6-311G* and MP2/6-311+G* levels of theory, with K{sup +}, Rb{sup +}, and Cs{sup +} represented by relativistic ECPs and associated valence basis sets. RHF/6-311G{sup {minus}} frequencies are used to verify that the optimized geometries are minima and to calculate binding enthalpies. The effects of basis set superposition error (BSSE) are estimated at both the RHF and MP2 levels. The alkali metals bind to anisole in two ways, either predominantly through interactions with themore » aromatic ring or with the ether oxygen. For binding to the ring, BSSE-corrected MP2/6-311+G* binding enthalpies (in kcal/mol) of {minus}38.1 (Li{sup +}), {minus}23.6 (Na{sup +}), {minus}18.3 (K{sup +}), {minus}15.4 (Rb{sup +}), and {minus}13.6 (Cs{sup +}) were obtained. The average distances (in {angstrom}) between the ring carbons and the cations are 2.33 (Li{sup +}), 2.79 (Na{sup +}), 3.20 (K{sup +}), 3.44 (Rb{sup +}), and 3.70 (Cs{sup +}). For binding to the ether oxygen, the BSSE-corrected MP2/6-311+G* binding enthalpies (in kcal/mol) are {minus}37.6 (Li{sup +}), {minus}25.2 (Na{sup +}), {minus}19.4 (K{sup +}), {minus}16.4 (Rb{sup +}), and {minus}14.3 (Cs{sup +}). The distances (in {angstrom}) between the ether oxygen and the cations are 1.82 (Li{sup +}), 2.24 (Na{sup +}), 2.62 (K{sup +}), 2.87 (Rb{sup +}), and 3.10 (Cs{sup +}). Although the differences in binding energy between the two sites are small, the cations generally prefer to bind to the oxygen.« less
  • Supported bimetallic catalysts consisting of a noble metal (e.g., Pt) and an oxophilic metal (e.g., Mo) have received considerable attention for the hydrodeoxygenation of oxygenated aromatic compounds produced from biomass fast pyrolysis. Here, we report that PtMo can catalyze m-cresol deoxygenation via a pathway involving an initial tautomerization step. In contrast, the dominant mechanism on monometallic Pt/Al 2O 3 was found to be sequential Pt-catalyzed ring hydrogenation followed by dehydration on the support. Bimetallic Pt 10Mo 1 and Pt 1Mo 1 catalysts were found to produce the completely hydrogenated and deoxygenated product, methylcyclohexane (MCH), with much higher yields than monometallicmore » Pt catalysts with comparable metal loadings and surface areas. Over an inert carbon support, MCH formation was found to be slow over monometallic Pt catalysts, while deoxygenation was significant for PtMo catalysts even in the absence of an acidic support material. Experimental studies of m-cresol deoxygenation together with density functional theory calculations indicated that Mo sites on the PtMo bimetallic surface dramatically lower the barrier for m-cresol tautomerization and subsequent deoxygenation. The accessibility of this pathway arises from the increased interaction between the oxygen of m-cresol and the Mo sites in the Pt surface. This interaction significantly alters the configuration of the precursor and transition states for tautomerization. Lastly, a suite of catalyst characterization techniques including X-ray absorption spectroscopy (XAS) and temperature-programmed reduction (TPR) indicate that Mo was present in a reduced state on the bimetallic surface under conditions relevant for reaction. Overall, these results suggest that the use of bifunctional metal catalysts can result in new reaction pathways that are unfavorable on monometallic noble metal catalysts.« less
  • Self-assembly of phenolic resins and a Pluronic block copolymer via the soft-template method enables the formation of well-organized polymeric mesostructures, providing an easy way for preparation of ordered mesoporous carbons (OMCs). However, direct synthesis of OMCs with high nitrogen content remains a significant challenge due to the limited availability of nitrogen precursors capable of co-polymerizing with phenolic resins without deterioration of the order of mesostructural arrangement and significant diminishment of nitrogen content during carbonization. Here in this work, we demonstrate pyrolysis of the soft-templated polymeric composites in ammonia as a direct, facile way towards nitrogen-enriched OMCs (N-OMCs). We find thismore » approach does not require any nitrogen-containing carbon precursors or post-treatment, but takes advantage of the preferential reaction and/or replacement of oxygen with nitrogen species, generated by decomposition of ammonia at elevated temperatures, in oxygen-rich polymers during pyrolysis. It combines carbonization, nitrogen functionalization, and activation into one simple process, generating N-OMCs with a uniform pore size, large surface area (up to 1400 m 2 g $-$1), and high nitrogen content (up to 9.3 at%). More importantly, the ordering of the meso-structure is well-maintained as long as the heating temperature does not exceed 800 °C, above which (e.g., 850 °C) a slight structural degradation is observed. When being used as electrode materials for symmetric electric double layer capacitors, N-OMCs demonstrate enhanced capacitance (6.8 μF cm $-$2vs. 3.2 μF cm $-$2) and reduced ion diffusion resistance compared to the non-NH 3-treated sample.« less