An In Situ Infrared Study of CO 2 Hydrogenation to Formic Acid by Using Rhodium Supported on Titanate Nanotubes as Catalysts Article uri icon

abstract

  • 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. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
  • 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 %2b 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. © 2019 Wiley-VCH Verlag GmbH %26 Co. KGaA, Weinheim

publication date

  • 2019-01-01