The sorption and crystallographic characteristics of alumina activated in a reactor for pneumatic transport

• Main Authors: LJILJANA ROZIC, TATJANA NOVAKOVIC, SRDJAN PETROVIC, ZELJKO CUPIC, ZELJKO GRBAVCIC, ALEKSANDAR ROSIC
• Format: Article
• Language: English
• Published: Serbian Chemical Society 2006-11-01
• Series: Journal of the Serbian Chemical Society
• Subjects: NH4F–extractable P; NaOH–extractable P; phosphorus-associations; principal component analysis
• Online Access: http://www.shd.org.yu/HtDocs/SHD/Vol71/No11/JSCS_V71_No11-11.pdf

Active transition alumina powders were obtained by flash calcination of gibbsite in a reactor for pneumatic transport in the dilute, two-phase flow regime in the temperature interval from 883 to 943 K with a residence time between 0.4 and 0.9 s. The results of X-ray diffraction analysis confirmed that the activated alumina samples were either microcrystalline or amorphous. From nitrogen adsorption–desorption isotherms, the specific surface areas of all samples were calculated by the BETmethod. Using the sorption data, the fractal dimension of the surface of the alumina samples was calculated according to a modified FHH method. By application of fractal geometry, using the values of the fractal dimension of the surface and of the specific surface area, the effective surface areas of the active aluminas were calculated for the adsorption of molecules having a cross-section area greater than that of the nitrogen molecule.