Abstract

Mesoporous alumina was one-pot synthesized via polymeric surfactant template assisted sol-gel and Evaporation-Induced Self-Assembly (EISA) using aluminum isopropoxide (Al(O-i-Pr)3) as aluminum source. Among several experimental parameters affecting the properties of the synthesized aluminas, the effect of calcination temperature and the triblock copolymer template (Pluronic P123) content in the gel were studied. The effects of calcination temperature in the range of 700°C–1050 °C, on such parameters as surface area, pore volume, pore size distribution, phase transformation, and crystal size were experimentally investigated. The influence of P123/Al(O-i-Pr)3mass ratio in the range of 0.49–1.96 on the textural properties of the synthesized alumina was studied. The synthesized mesoporous alumina was characterized using N2 adsorption-desorption analysis, TGA/DTG and DSC/DTA. The phase identification and crystal domain size were determined using XRD. The morphology of the calcined samples was analyzed using SEM and TEM. The TEM observations and SAXS measurements revealed the mesostructured pore lattice of the samples. The pore diameter distributions were estimated by numerical image analysis of TEM images. The pore lengths distributions were also estimated using the scale bar of TEM images and found to be averaged around 800 nm. The calculated volume pore size distributions (PSD) were found in reasonable agreement with the PSDs obtained from NLDFT analysis of nitrogen adsorption-desorption isotherms. The synthesized γ-aluminas exhibited thermal stability up to 950 °C. At higher temperatures, the α-phase was formed, and the mesostructure collapsed. Samples obtained with P123/Al(O-i-Pr)3 = 0.98 and 1.47, calcined at 700 °C with 3 h soaking time exhibited a surface area of 259 m2/g and 238 m2/g respectively.

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