Surface modification of alumina by metal doping

A series of metal impregnated alumina samples were prepared by incipient wetness impregnation technique. Pore structure and surface area for metal doped alumina (Cr, Mn, Fe and Co) containing different concentration of metals was assessed by mercury penetration and low temperature nitrogen adsorption. It was observed that mercury intrusion and extrusion curves are irreversible giving the evidence of ‘ink bottle’ pores in the alumina samples. From comparison of results of mercury porosimeter, it was also noted that total pore area values decreased with increasing metal concentration. Nitrogen adsorption data revealed that surface area decreased with increasing metal fraction (due to dispersion of metal residues on the surface of alumina samples). On the other hand, metal concentration per unit area increased with increasing the amount of metal used in doping.