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Title: An investigation into support cooperativity for the deoxygenation of guaiacol over nanoparticle Ni and Rh 2P

Abstract

Here, the production of hydrocarbon fuels from biomass pyrolysis requires the development of effective deoxygenation catalysts, and insight into how the properties of the support influence performance is critical for catalyst design. In this report, nanoparticles of Ni and Rh 2P were synthesized using solution-phase techniques and dispersed on high surface area supports. The supports included a relatively inert material (C), an acidic reducible metal-oxide (TiO 2), an acidic irreducible metal-oxide (Al 2O 3), and a basic irreducible metal-oxide (MgO). The eight active phase/support combinations were investigated for the deoxygenation of guaiacol, a pyrolysis vapor model compound, under ex situ catalytic fast pyrolysis conditions (350 °C, 0.44 MPa H 2). Compared to the baseline performance of the C-supported catalysts, Ni/TiO 2 and Rh 2P/TiO 2 exhibited higher guaiacol conversion and lower O : C ratios for C 5+ products, highlighting the enhanced activity and greater selectivity to deoxygenated products derived from the use of an acidic reducible metal-oxide support. The Al 2O 3-supported catalysts also exhibited higher conversion than the C-supported catalysts and promoted alkylation reactions, which improve carbon efficiency and increase the carbon number of the C 5+ products. However, Ni/Al 2O 3 and Rh 2P/Al 2O 3 weremore » less selective towards deoxygenated products than the C-supported catalysts. The MgO-supported catalyst exhibited lower conversion and decreased yield of deoxygenated products compared to the C-supported catalysts. The results reported here suggest that basic metal-oxide supports may inhibit deoxygenation of phenolics under CFP conditions. Contrastingly, support acidity and reducibility were demonstrated to promote conversion and selectivity to deoxygenated products, respectively.« less

Authors:
 [1];  [1];  [1];  [1];  [1]; ORCiD logo [1]
  1. National Renewable Energy Lab. (NREL), Golden, CO (United States)
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Bioenergy Technologies Office (EE-3B)
OSTI Identifier:
1372621
Report Number(s):
NREL/JA-5100-67975
Journal ID: ISSN 2044-4753; CSTAGD
Grant/Contract Number:
AC36-08GO28308
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Catalysis Science and Technology
Additional Journal Information:
Journal Volume: 7; Journal Issue: 14; Journal ID: ISSN 2044-4753
Publisher:
Royal Society of Chemistry
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; catalytic fast pyrolysis; deoxygenation; nanoparticle; metal phosphide; support effect

Citation Formats

Griffin, Michael B., Baddour, Frederick G., Habas, Susan E., Nash, Connor P., Ruddy, Daniel A., and Schaidle, Joshua A. An investigation into support cooperativity for the deoxygenation of guaiacol over nanoparticle Ni and Rh2P. United States: N. p., 2017. Web. doi:10.1039/C7CY00261K.
Griffin, Michael B., Baddour, Frederick G., Habas, Susan E., Nash, Connor P., Ruddy, Daniel A., & Schaidle, Joshua A. An investigation into support cooperativity for the deoxygenation of guaiacol over nanoparticle Ni and Rh2P. United States. doi:10.1039/C7CY00261K.
Griffin, Michael B., Baddour, Frederick G., Habas, Susan E., Nash, Connor P., Ruddy, Daniel A., and Schaidle, Joshua A. 2017. "An investigation into support cooperativity for the deoxygenation of guaiacol over nanoparticle Ni and Rh2P". United States. doi:10.1039/C7CY00261K.
@article{osti_1372621,
title = {An investigation into support cooperativity for the deoxygenation of guaiacol over nanoparticle Ni and Rh2P},
author = {Griffin, Michael B. and Baddour, Frederick G. and Habas, Susan E. and Nash, Connor P. and Ruddy, Daniel A. and Schaidle, Joshua A.},
abstractNote = {Here, the production of hydrocarbon fuels from biomass pyrolysis requires the development of effective deoxygenation catalysts, and insight into how the properties of the support influence performance is critical for catalyst design. In this report, nanoparticles of Ni and Rh2P were synthesized using solution-phase techniques and dispersed on high surface area supports. The supports included a relatively inert material (C), an acidic reducible metal-oxide (TiO2), an acidic irreducible metal-oxide (Al2O3), and a basic irreducible metal-oxide (MgO). The eight active phase/support combinations were investigated for the deoxygenation of guaiacol, a pyrolysis vapor model compound, under ex situ catalytic fast pyrolysis conditions (350 °C, 0.44 MPa H2). Compared to the baseline performance of the C-supported catalysts, Ni/TiO2 and Rh2P/TiO2 exhibited higher guaiacol conversion and lower O : C ratios for C5+ products, highlighting the enhanced activity and greater selectivity to deoxygenated products derived from the use of an acidic reducible metal-oxide support. The Al2O3-supported catalysts also exhibited higher conversion than the C-supported catalysts and promoted alkylation reactions, which improve carbon efficiency and increase the carbon number of the C5+ products. However, Ni/Al2O3 and Rh2P/Al2O3 were less selective towards deoxygenated products than the C-supported catalysts. The MgO-supported catalyst exhibited lower conversion and decreased yield of deoxygenated products compared to the C-supported catalysts. The results reported here suggest that basic metal-oxide supports may inhibit deoxygenation of phenolics under CFP conditions. Contrastingly, support acidity and reducibility were demonstrated to promote conversion and selectivity to deoxygenated products, respectively.},
doi = {10.1039/C7CY00261K},
journal = {Catalysis Science and Technology},
number = 14,
volume = 7,
place = {United States},
year = 2017,
month = 6
}

Journal Article:
Free Publicly Available Full Text
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  • Molybdenum carbide has been identified as a promising bifunctional catalyst in the deoxygenation of a variety of pyrolysis vapor model compounds. Although high deoxygenation activity has been demonstrated, complementary hydrogenation activity has been limited, especially for lignin-derived, aromatic model compounds. The ability to control the relative site densities of acidic and hydrogenation functionalities represents a catalyst design challenge for these materials with the goal to improve hydrogenation activity under ex situ catalytic fast pyrolysis (CFP) conditions. Here in this paper, we demonstrate that the addition of Pt and Ni to Mo 2C resulted in an increase in the H*-site densitymore » with only a minor decrease in the acid-site density. In contrast, the addition of Pd did not significantly alter the H* or acid site densities. High conversions (>94%) and high selectivities to 0-oxygen products (>80%) were observed in guaiacol deoxygenation under ex situ CFP conditions (350 °C and 0.44 MPa H 2) for all catalysts. Pt addition resulted in the greatest deoxygenation, and site-time yields to hydrogenated products over the Pt/Mo 2C catalyst were increased to 0.048 s -1 compared to 0.015-0.019 s -1 for all other catalysts. The Pt/Mo 2C catalyst demonstrated the highest hydrogenation performance, but modification with Ni also significantly enhanced hydrogenation performance, representing a promising lower-cost alternative.« less
  • The catalytic deoxygenation of biomass fast pyrolysis vapors offers a promising route for the sustainable production of liquid transportation fuels. However, a clear understanding of the mechanistic details involved in this process has yet to be achieved, and questions remain regarding the role of the catalyst support and the influence of reaction conditions. In order to gain insight into these questions, the deoxygenation of m-cresol was investigated over Pt/C and Pt/TiO 2 catalysts using experimental and computational techniques. The performance of each catalyst was evaluated in a packed-bed reactor under two conditions (523 K, 2.0 MPa and 623 K, 0.5more » MPa), and the energetics of the ring hydrogenation, direct deoxygenation, and tautomerization mechanisms were calculated over hydrogen-covered Pt(111) and oxygen vacancies on the surface of TiO 2(101). Over Pt(111), ring hydrogenation to 3-methylcyclohexanone and 3-methylcyclohexanol was found to be the most energetically favorable pathway. Over TiO 2(101), tautomerization and direct deoxygenation to toluene were identified as additional energetically favorable routes. These calculations are consistent with the experimental data, in which Pt/TiO 2 was more active on a metal site basis and exhibited higher selectivity to toluene at 623 K relative to Pt/C. On the basis of these results, it is likely that the reactivity of Pt/TiO 2 and Pt/C is driven by the metallic phase at 523 K, while contributions from the TiO 2 support enhance deoxygenation at 623 K. These results highlight the synergistic effects between hydrogenation catalysts and reducible metal oxide supports and provide insight into the reaction pathways responsible for their enhanced deoxygenation performance.« less
  • Ex situ catalytic fast pyrolysis (CFP) is a promising route for producing fungible biofuels; however, this process requires bifunctional catalysts that favor C–O bond cleavage, activate hydrogen at near atmospheric pressure and high temperature (350–500 °C), and are stable under high-steam, low hydrogen-to-carbon environments. Recently, early transition-metal carbides have been reported to selectively cleave C–O bonds of alcohols, aldehydes, and oxygenated aromatics, yet there is limited understanding of the metal carbide surface chemistry under reaction conditions and the identity of the active sites for deoxygenation. In this study, we evaluated molybdenum carbide (Mo 2C) for the deoxygenation of acetic acid,more » an abundant component of biomass pyrolysis vapors, under ex situ CFP conditions, and we probed the Mo 2C surface chemistry, identity of the active sites, and deoxygenation pathways using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations.« less