Influence of salts on the subcritical water-gas shift reaction

The water-gas shift reaction is the key reaction to produce hydrogen by hydrothermal biomass gasification. Salts are ingredients of biomass and accelerate the water-gas shift reaction. In this work, the influences of the NaHCO3 and the KHCO3 on water-gas shift reaction (WGSR) were investigated at 10 and 23 MPa and 230–300 °C. The presence of NaHCO3 and KHCO3 promotes the WGSR significantly and to the same extend. Additionally, sodium and potassium formate salts are formed from the carbonates. The water-gas shift reaction rate in the presence of salts is found to be:1.16×104   (l mol−1)0.5 s−1 e(−9155 K/T)   [CO][NaHCO3]0.5.1.16×104   (l mol−1)0.5 s−1 e(−9155 K/T)   [CO][NaHCO3]0.5.

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► Alkali salts increase the reaction rate of the water-gas shift reaction (WGSR).
► NaHCO3 and KHCO3 have the same effect on WGSR.
► Formic acid, the intermediate of the WGSR, is influenced differently.
► Kinetic parameters for the WGSR and formic acid degradation are presented.
► A ceramic lined reactor was used to avoid catalysis by the wall.