Structuration of Pd(2 wt %)/Fe-Al Oxide Catalysts on Ceramic and Metallic Monoliths: Physicochemical Characterization, Effect of the Nature of the Slurry, and Comparison with LaMnO3 Catalysts

The main objective of this study has been twofold: (i) to investigate the effect of the nature of the slurry used to structurate a catalyst oil monoliths; (ii) to study the influence of the nature of the monoliths oil the physicochemical properties and on the catalytic activities in the combustion of methane. The slurry used in this work was made with an acidified solution of Pd(2 wt %)/Fe-Al oxide catalyst. This catalyst was prepared by the citrate method and deposited oil ceramic and metallic monoliths according to a dip coating or an orbital stirring procedure. Both types of structured catalysts were studied using the following physicochemical techniques: specific surface area measurements (BET), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The Pd(2 wt %)[Fe-Al oxide catalyst used for monolith coating does not undergo any textural or crystallinity modification during the deposition procedure. Catalytic activities obtained for powder and monolithic catalysts are compared. The Surface of the support plays an important role in the structuration of catalysts. The amount of deposited catalyst has an influence on the catalytic activity. The amount of deposited catalysts depends oil the nature of the monolith, oil the coating technique, and oil the nature of the Slurry. Comparisons between structured Pd(2 wt %)/Fe-Al oxide and structured LaMnO3 on ceramic and metallic monoliths (previous work) were made to clarify the influence of the nature of the slurry oil the amount of deposited catalysts. The amount of deposited catalysts oil ceramic monolith using Pd(2 wt %)[Fe-Al oxide catalyst is lower than that deposited using LaMnO3, In the case of metallic monoliths, the difference is less significant. The influence of a diffusion limitation of the reaction rate in structured catalysts with Pd(2 wt %)/Fe-Al oxide seems to be less important than with LaMnO3. Higher catalytic activities were observed for Pd(2 wt %)/Fe-Al oxide on the ceramic monoliths at high temperature. Coating oil the metallic monoliths led to a better activity at low temperature compared to the corresponding powder catalyst.