Sol–gel derived Cr(III) and Cu(II)/γ-Al2O3 doped solids: Effect of the dopant precursor nature on the structural, textural and morphological properties

Powders of xerogel γ-Al2O3 doped with various concentrations of Cr3+ and Cu2+ (M/M + Al molar fraction = 0.75–10%) were prepared via a sol–gel method. Cr3+ and Cu2+ precursors (acetylacetonate, nitrate or chloride) were added to 0.12 M 2-propanol solution of aluminum tri-sec-butoxide (ASB) and hydrolysis was performed using a H2O/ASB molar ratio of 4.7. The effect of the dopant precursor on structural, textural and morphological properties was studied. Employing acac precursors resulted in unique properties after calcination at 500 °C including high surface areas, as high as 455 m2/g, homogeneous mesopores, 3–12 nm, and amorphous powders (5–10 nm particles in diameter). On the other hand, the acac precursor enhanced the resistance to sintering mainly at higher metal loads (10%) and elevated temperature (800 °C). Nevertheless, the solids issued from nitrate and chloride precursors exhibited lower surface areas at high metal loads, and lower resistance to sintering.