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An In Situ Infrared Study of CO 2 Hydrogenation to Formic Acid by Using Rhodium Supported on Titanate Nanotubes as Catalysts
Author(s) -
RuizGarcía Jesús Roberto,
FierroGonzalez Juan Carlos,
Handy Brent E.,
HinojosaReyes Laura,
De Haro Del Río David A.,
LucioOrtiz Carlos J.,
ValleCervantes Sergio,
FloresEscamilla Gerardo A.
Publication year - 2019
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201900361
Subject(s) - rhodium , x ray photoelectron spectroscopy , catalysis , raman spectroscopy , formic acid , formate , infrared spectroscopy , fourier transform infrared spectroscopy , materials science , diffuse reflectance infrared fourier transform , analytical chemistry (journal) , chemistry , inorganic chemistry , chemical engineering , photocatalysis , organic chemistry , physics , optics , engineering
Titanate nanotubes (TiNT) were synthesized by hydrothermal method and used as support of rhodium nanoparticles. Results of X‐Ray diffraction (XRD) and Raman spectroscopy of TiNT revealed its structure of Na 2 Ti 3 O 7 , while the results of Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and physisorption of N 2 confirmed the multilayer nanotubular morphology with external diameter of ∼12 nm, length > 100 nm and a BET surface area of 195 m 2 g −1 . The TEM analysis of the rhodium supported sample (Rh/TiNT) showed evidence of small (∼1 nm) and highly dispersed rhodium particles. Results of X‐Ray Photoelectron Spectroscopy (XPS) revealed a strong electronic interaction between TiNT and Rh sites. The catalytic activity of Rh/TiNT for the hydrogenation of CO 2 to formic acid at moderate temperature (∼40 °C) and atmospheric pressure was demonstrated as evidenced by results of Mass Spectrometry (MS) and in‐situ Diffuse Reflectance Infrared with Fourier Transform Spectroscopy (DRIFTS). The in‐situ studies showed active surface species bonded to support sites and to rhodium sites. It is proposed that under H 2 atmosphere, Na + cations near to Rh particles promote the conversion of CO 2 via dissociated H, allowing the formation of formate species at low temperature. The formate species and the hydride rhodium complexes are considered reaction intermediates.