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Control of Phase and Pore Structure of Titania Powders Using HCl and NH 4 OH Catalysts
Author(s) -
Song Ki Chang,
Pratsinis Sotiris E.
Publication year - 2001
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.2001.tb00613.x
Subject(s) - anatase , calcination , crystallinity , materials science , porosity , rutile , phase (matter) , amorphous solid , chemical engineering , hydrolysis , titanium , catalysis , inorganic chemistry , mineralogy , nuclear chemistry , chemistry , photocatalysis , crystallography , metallurgy , organic chemistry , composite material , engineering
Porous titania powders were prepared by hydrolysis of titanium tetraisopropoxide (TTIP) and were characterized at various calcination temperatures by nitrogen adsorption, X‐ray diffraction, and microscopy. The effect of HCl or NH 4 OH catalysts added during hydrolysis on the crystallinity and porosity of the titania powders was investigated. The HCl enhanced the phase transformations of the titania powders from amorphous to anatase as well as anatase to rutile, while NH 4 OH retarded both phase transformations. Titania powders calcined at 500°C showed bimodal pore size distributions: one was intra‐aggregated pores with average pore diameters of 3–6 nm and the other was interaggregated pores with average pore diameters of 35–50 nm. The average intra‐aggregated pore diameter was decreased with increasing HCl concentration, while it was increased with increasing NH 4 OH concentration.