Synthesis and characterization of mesoporous alumina with high specific area via coprecipitation method

• Alum as raw material was obtained from sintering coal fly ash with ammonium sulfate.
• The high specific surface area of alumina obtained in experiment is 571.32 m2/g.
• Mesoporous alumina was applied to adsorbents, catalyst and catalyst support.

Mesoporous γ-Al2O3 with high specific surface area is prepared via calcination of NH4Al(OH)2CO3 (AACH). The AACH is obtained by coprecipitation route with NH4HCO3 and NH4Al(SO4)2 as raw materials. The effects of pH value and calcination temperature on the characterization of products are investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N2 adsorption-desorption method and Transmission electron microscopy (TEM). The results show that mesoporous γ-Al2O3 obtained by calcining AACH at 500 °C for 4 h exhibits high specific surface area of 571.32 m2/g, a pore volume of 0.75 cm3/g and pore size of 6.15 nm. With the calcining temperature increase, the specific surface area and pore volume decrease, and the pore size increase. When the calcining temperature elevates up to 900 °C which is higher than the application temperature of most active agents, the specific surface area of 150.67 m2/g, the pore volume of 0.51 cm3/g and pore size of 9.65 nm was obtained.