Effects of NaOH concentration on CO2 reduction via hydrothermal water

Takamasa Onoki, Hiro Takahashi, Toshinari Kori, Nakamichi Yamasaki, Toshiyuki Hashida

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)


The reductions of CO2 under hydrothermal conditions were investigated by using the micro autoclave (45cm3) lined with Hastelloy-C alloy. Sodium hydrogen carbonate (NaHCO3) was used as a starting material. H2 gas was used as reducing agents. NaHCO 3 powder, H2 gas and water put into the autoclave simultaneously. The autoclave was heated upto 300°C by induction heater. In this study, effects of pH value of the NaOH solution in the autoclave are investigated. Reaction products were analyzed with gas chromatographs (GC), liquid chromatographs (LC), X-ray diffractometor (XRD) and Scanning electron microscopy (SEM). The following things were showed in this research: CO 2 was reducted to HCOO- and CH4 at high conversion ratio under hydrothermal conditions. HCOO- was formed at high selectivity using Hastelloy-C reactor in the alkaline solution with Raney Ni catalyst. Raney Ni was exellent methanation catalyst, and CH4 formation progressed via HCO3-, not via CO. It is cleared that the NaOH solution in the autoclave should be kept pH value 11.0 for the highest conversion ratio from CO2 to useful carbonic compounds (CH4, HCOO-).

Original languageEnglish
Title of host publicationWATER DYNAMICS
Subtitle of host publication3rd International Workshop on Water Dynamics
Number of pages4
Publication statusPublished - 2006 May 15
EventWATER DYANMICS: 3rd International Workshop on Water Dynamics - Sendai, Japan
Duration: 2005 Nov 162005 Nov 17

Publication series

NameAIP Conference Proceedings
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616


OtherWATER DYANMICS: 3rd International Workshop on Water Dynamics


  • H
  • Hydrothermal
  • Raney-Ni
  • pH

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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