Hydrothermal preparation and characterization of boehmites
2000; Elsevier BV; Volume: 42; Issue: 1-2 Linguagem: Inglês
10.1016/s0167-577x(99)00156-1
ISSN1873-4979
AutoresDilip Kumar Mishra, S. Anand, R. K. PANDA, R.P. Das,
Tópico(s)Clay minerals and soil interactions
ResumoBoehmites (Al2O3·xH2O, 1<x<1.5) have been prepared hydrothermally from Al(NO3)3·9H2O and urea. Effect of temperature on preparation was studied in the range of 160°–220°C. No precipitation of boehmite was observed until the attainment of ∼160°C at which temperature a partly amorphous gel started precipitating. With the increase in temperature, transformation of the amorphous precipitate into crystalline boehmites took place as indicated by the X-ray diffraction (XRD) patterns. From the weight loss studies of the samples prepared at different temperatures and for different reaction time intervals, the value of x was estimated to vary between 1.3 and 1.5. The Fourier transform infrared (FTIR) spectra of samples obtained at 180°, 200° or 220°C showed 25–40 cm−1 upward shift in the –OH stretching and bending vibrations assigned to boehmites. γ-Alumina obtained by subsequent calcination of boehmite at 725°C was also characterized by XRD.
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