10.1021/acssuschemeng.9b00672.s001
David
L. Williamson
David
L.
Williamson
Carmelo Herdes
Carmelo
Herdes
Laura Torrente-Murciano
Laura
Torrente-Murciano
Matthew D. Jones
Matthew D.
Jones
Davide Mattia
Davide
Mattia
N‑Doped Fe@CNT for Combined RWGS/FT CO<sub>2</sub> Hydrogenation
American Chemical Society
2019
greenhouse gas emission reductions
CO 2
interaction
FT
graphitic carbon materials
Current research places
CO 2 conversion
catalysi
CNT
CO 2 hydrogenation
RWGS
catalyst
2019-03-11 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/N_Doped_Fe_CNT_for_Combined_RWGS_FT_CO_sub_2_sub_Hydrogenation/7848215
The conversion of CO<sub>2</sub> into
chemical fuels represents
an attractive route for greenhouse gas emission reductions and renewable
energy storage. Iron nanoparticles supported on graphitic carbon materials
(e.g., carbon nanotubes (CNTs)) have proven themselves to be effective
catalysts for this process. This is due to their stability and ability
to support simultaneous reverse water-gas shift (RWGS) and Fischer–Tropsch
(FT) catalysis. Typically, these catalytic iron particles are postdoped
onto an existing carbon support via wet impregnation. Nitrogen doping
of the catalyst support enhances particle–support interactions
by providing electron-rich anchoring sites for nanoparticles during
wet impregnation. This is typically credited for improving CO<sub>2</sub> conversion and product selectivity in subsequent catalysis.
However, the mechanism for RWGS/FT catalysis remains underexplored.
Current research places significant emphasis on the importance of
enhanced particle–support interactions due to N doping, which
may mask further mechanistic effects arising from the presence or
absence of nitrogen during CO<sub>2</sub> hydrogenation. Here we report
a clear relationship between the presence of nitrogen in the CNT support
of an RWGS/FT iron catalyst and significant shifts in the activity
and product distribution of the reaction. Particle–support
interactions are maximized (and discrepancies between N-doped and
pristine support materials are minimized) by incorporating iron and
nitrogen directly into the support during synthesis. Reactivity is
thus rationalized in terms of the influence of C–N dipoles
in the support upon the adsorption properties of CO<sub>2</sub> and
CO on the surface rather than improved particle–support interactions.
These results show that the direct hydrogenation of CO<sub>2</sub> to hydrocarbons is a potentially viable route to reduce carbon emissions
from human activities.