Pd-supporting LaCoO3 catalyst with structured configuration for water gas shift reaction

• A structured perovskite catalyst was developed for the water gas shift reaction.
• By loading Pd, the performance of the LaCoO3 structured catalyst was improved.
• The Pd-promoted catalyst prepared using PdCl2 solution showed the highest activity.
• High activity was due to the highly dispersed state of Pd on the support.
• The washing process by NH3aq. was effective for improving the shift activity.

The purpose of this study was to develop a structured perovskite-type oxide catalyst for the water gas shift (WGS) reaction, which could make lattice oxygen mobile at a low external heat energy by preparing it as a thin catalyst layer on a metal plate. The thickness of the formed LaCoO3 layer was about 20 μm, which was confirmed by FE-SEM and EDX analysis. For enhancing its WGS reaction performance, a palladium (Pd) component was supported on the structured catalyst using various Pd precursors. When using a PdCl2 aqueous solution which was prepared by filtration of the PdCl2 slurry (the filtration liquid), the Pd-supporting LaCoO3 structured catalyst showed a high and stable activity. The reason for such an enhanced activity was that the supported Pd was in a highly dispersed state, which was derived from the electrostatic interaction between [PdCl3(H2O)]− as the anionic charged precursor in the filtration liquid and the oppositely charged LaCoO3 support surface confirmed by a UV–vis measurement. In order to remove the remaining chloride ligand from the Pd-supporting LaCoO3 catalyst surface, a washing treatment was performed by immersing the as-made catalyst in water, NH3 (aq) or NaOH (aq) at pH 11.5 for 30 min. Consequently, these washing processes were effective for eliminating the remaining chloride ion from the catalyst surface and improving the shift activity of the catalyst. The catalyst washed using NH3 (aq) showed the highest activity among these catalysts.

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