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Title: O-Functionalized CNT Mediated CO Hydro-Deoxygenation and Chain Growth

Abstract

Worldwide energy independence is reliant on the ability to leverage locally available resources for fuel production. Recently, syngas produced through gasification of carbonaceous materials provided a gateway to a host of processes for the production of various chemicals including transportation fuels. The basis of the production of gasoline and diesel-like fuels is the Fischer Tropsch Synthesis (FTS) process: A catalyzed chemical reaction that converts a mixture of carbon monoxide (CO) and hydrogen (H 2) into long chain hydrocarbons. Until now, it has been argued that only transition metal catalysts (usually Co or Fe) are active toward the CO hydrogenation and subsequent chain growth in the presence of hydrogen. In this paper, we demonstrate that carbon nanotube (CNT) surfaces are also capable of hydro-deoxygenating CO and producing long chain hydrocarbons similar to that obtained through the FTS but with orders of magnitude higher conversion efficiencies than the present state-of-the-art FTS catalysts. We have used advanced experimental tools such as XPS and microscopy techniques to characterize CNTs and identify C-O functional groups as the active sites for the enhanced catalytic activity. Furthermore, we have conducted quantum Density Functional Theory (DFT) calculations to confirm that C-O groups (inherent on CNT surfaces) could indeedmore » be catalytically active towards reduction of CO with H 2, and capable of sustaining chain growth. The DFT calculations have shown that the kinetically and thermodynamically feasible route for CO insertion and hydro-deoxygenation are different from that on transition metal catalysts. Experiments on a continuous flow tubular reactor with various nearly metal-free CNTs have been carried out and the products have been analyzed. CNTs functionalized by various methods were evaluated under different conditions. Reactor tests revealed that the hydrogen pre-treatment reduced the activity of the catalysts to negligible levels. Without the pretreatment, the activity for CO conversion as found to be 7 µmol CO/g CNT/s. The O-functionalized samples showed very activities greater than 85 µmol CO/g CNT/s with nearly 100% conversion. Analyses show that CO hydro-deoxygenation occurred at the C-O/O-H functional groups. It was found that while the products were similar to FT products, differences in selectivities were observed which, in turn, was a result of a different catalytic mechanism. Furthermore, these findings now open a new paradigm for CNT-based hydrogenation catalysts and constitute a defining point for obtaining clean, earth abundant, alternative fuels through the use of efficient and renewable catalyst.« less

Authors:
 [1];  [1];  [2];  [1];  [3]; ORCiD logo [4];  [2];  [2]
  1. Southern Illinois Univ., Carbondale, IL (United States)
  2. Pennsylvania State Univ., University Park, PA (United States)
  3. MidAmerican Nazarene University
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1474624
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
World Academy of Science, Engineering and Technology International Journal of Chemical and Molecular Engineering
Additional Journal Information:
Journal Volume: 11; Journal Issue: 7; Journal ID: ISSN 1307-6892
Publisher:
World Academy of Science
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; CNT; CO hydro-deoxygenation; DFT; liquid fuels; XPS; XTL

Citation Formats

Mondal, Kanchan, Talapatra, S., Terrones, Mauricio, Pokhrel, Sewa, Frizzel, C., Sumpter, Bobby G., Meunier, Vincent, and Elias, Ana Laura. O-Functionalized CNT Mediated CO Hydro-Deoxygenation and Chain Growth. United States: N. p., 2017. Web.
Mondal, Kanchan, Talapatra, S., Terrones, Mauricio, Pokhrel, Sewa, Frizzel, C., Sumpter, Bobby G., Meunier, Vincent, & Elias, Ana Laura. O-Functionalized CNT Mediated CO Hydro-Deoxygenation and Chain Growth. United States.
Mondal, Kanchan, Talapatra, S., Terrones, Mauricio, Pokhrel, Sewa, Frizzel, C., Sumpter, Bobby G., Meunier, Vincent, and Elias, Ana Laura. Fri . "O-Functionalized CNT Mediated CO Hydro-Deoxygenation and Chain Growth". United States. https://www.osti.gov/servlets/purl/1474624.
@article{osti_1474624,
title = {O-Functionalized CNT Mediated CO Hydro-Deoxygenation and Chain Growth},
author = {Mondal, Kanchan and Talapatra, S. and Terrones, Mauricio and Pokhrel, Sewa and Frizzel, C. and Sumpter, Bobby G. and Meunier, Vincent and Elias, Ana Laura},
abstractNote = {Worldwide energy independence is reliant on the ability to leverage locally available resources for fuel production. Recently, syngas produced through gasification of carbonaceous materials provided a gateway to a host of processes for the production of various chemicals including transportation fuels. The basis of the production of gasoline and diesel-like fuels is the Fischer Tropsch Synthesis (FTS) process: A catalyzed chemical reaction that converts a mixture of carbon monoxide (CO) and hydrogen (H2) into long chain hydrocarbons. Until now, it has been argued that only transition metal catalysts (usually Co or Fe) are active toward the CO hydrogenation and subsequent chain growth in the presence of hydrogen. In this paper, we demonstrate that carbon nanotube (CNT) surfaces are also capable of hydro-deoxygenating CO and producing long chain hydrocarbons similar to that obtained through the FTS but with orders of magnitude higher conversion efficiencies than the present state-of-the-art FTS catalysts. We have used advanced experimental tools such as XPS and microscopy techniques to characterize CNTs and identify C-O functional groups as the active sites for the enhanced catalytic activity. Furthermore, we have conducted quantum Density Functional Theory (DFT) calculations to confirm that C-O groups (inherent on CNT surfaces) could indeed be catalytically active towards reduction of CO with H2, and capable of sustaining chain growth. The DFT calculations have shown that the kinetically and thermodynamically feasible route for CO insertion and hydro-deoxygenation are different from that on transition metal catalysts. Experiments on a continuous flow tubular reactor with various nearly metal-free CNTs have been carried out and the products have been analyzed. CNTs functionalized by various methods were evaluated under different conditions. Reactor tests revealed that the hydrogen pre-treatment reduced the activity of the catalysts to negligible levels. Without the pretreatment, the activity for CO conversion as found to be 7 µmol CO/g CNT/s. The O-functionalized samples showed very activities greater than 85 µmol CO/g CNT/s with nearly 100% conversion. Analyses show that CO hydro-deoxygenation occurred at the C-O/O-H functional groups. It was found that while the products were similar to FT products, differences in selectivities were observed which, in turn, was a result of a different catalytic mechanism. Furthermore, these findings now open a new paradigm for CNT-based hydrogenation catalysts and constitute a defining point for obtaining clean, earth abundant, alternative fuels through the use of efficient and renewable catalyst.},
doi = {},
journal = {World Academy of Science, Engineering and Technology International Journal of Chemical and Molecular Engineering},
issn = {1307-6892},
number = 7,
volume = 11,
place = {United States},
year = {2017},
month = {9}
}

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