The structural and functional roles of lanthana in high-temperature Fe2O3/Cr2O3/CuO water-gas shift catalysts were studied. Different batches of catalysts were prepared via co-precipitation with 8 wt % Cr2O3, 4 wt% CuO, and varying wt% (0, 0.5, 1, 2, and 5) of lanthana added at the expense of iron oxide. The catalysts were characterized using surface area measurements, scanning-electron microscopy, temperature-programmed reduction, and powder X-ray diffraction. The kinetics and stability were analyzed for different reaction temperatures.The results showed that addition of 0.5 wt% of lanthana promoted the WGS activity and produced a more stable catalyst. Further additions of lanthana appeared to impose a negative effect on the catalysts, possibly due to the disruption of the iron-chromium spinel with the bigger ionic sizes of La3+. TPR results showed that addition the catalyst with 0.5 wt% of lanthana was the easiest to reduce. Figure 1. <img src='https://acs-archive-assets2.s3.amazonaws.com/239nm/uploads/11670_synthesis_of_ddivdu_and_ic50_of_ddivdu_and_gcv_in_mca_and_mca-tk_cells.jpg' alt='' />Rate data were fit to Langmuir Hinshelwood, oxidation-reduction, and power-law rate models. Langmuir-Hinshelwood provided much better fits than the redox model, suggesting that the reaction tends to follow an adsorptive mechanism. The CO adsorption equilibrium constant was found to be largest for the catalyst with 0.5 wt% lanthana, indicating a better surface is available for CO adsorption.

Understanding the structural and functional roles of lanthana in iron-based catalysts for high-temperature water-gas shift reaction

246th National Meeting (2013)

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