Chemical Engineering Communications, Vol.204, No.10, 1129-1142, 2017
Effective diffusion constant and adsorption constant of synthesized alumina, zirconia, and alumina-zirconia composite material
In this study, Al2O3, ZrO2, and Al2O3-ZrO2 composite materials were prepared with the sol-gel technique. X-ray diffraction analysis, differential scanning calorimetry-thermogravimetry, scanning electron microscopy-energy-dispersive X-ray spectrometry, nitrogen adsorption isotherm measurements, and helium pycnometry were used to characterize the resultant materials. Effective diffusion coefficients of helium and hydrogen and the adsorption equilibrium constant of hydrogen in the resultant materials were determined using single-pellet moment technique. The effective diffusivities of helium and hydrogen in both ZrO2 and Al2O3-ZrO2 composite pellets were found to be smaller than the value found for Al2O3, due to the lower tortuosity factor values of the Al2O3 pellet. It was found that hydrogen was weakly adsorbed on all resultant materials.
Keywords:Adsorption constant;alumina zirconia composite material;effective diffusion constant;single-pellet moment technique;sol-gel process;tortuosity