Investigating mass transfer coefficients in lean methane combustion reaction through the morphological and geometric analysis of structured open cell foam catalysts

In this work, we characterized ceramic open cell foams made of zirconia, silicon carbide and alumina of different nominal pore densities (30-45 ppi) using X-ray computed microtomography. This technique allowed the comprehensive and quantitative extraction of morphological and geometrical characteristics of the structures (pore size, strut diameter and length, node diameter, open porosity and specific geometrical surface area). An empirical model was proposed to determine the specific surface area from parameters easily accessible with standard laboratory equipment. Moreover, lean CH4 combustion tests were performed on ceramic foams coated with PdO/Co3O4 at 3 wt%. Mass transfer coefficients of the foams were measured by monitoring the oxidation reaction under diffusional control conditions. We derived a dimensionless correlation of the type Sh = A & BULL;Rem & BULL;Sc1/3. Finally, the pressure drop across the foams as a function of surface velocity was evaluated and compared with various experimental data and models available in the literature.

Automated summary

In this study, ceramic open cell foams made of zirconia, silicon carbide, and alumina with different pore densities were characterized using X-ray computed microtomography. Morphological and geometrical characteristics of the foams were comprehensively extracted, and an empirical model was proposed to determine the specific surface area. Lean CH4 combustion tests were performed on coated ceramic foams, and mass transfer coefficients were measured. Finally, the pressure drop across the foams as a function of surface velocity was evaluated and compared with existing experimental data and models.