1070-4272/05/7802-0171 C 2005 Pleiades Publishing, Inc.
Russian Journal of Applied Chemistry, Vol. 78, No. 2, 2005, pp. 171!177. Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 2, 2005,
Original Russian Text Copyright + 2005 by Lamberov, Aptikasheva, Egorova, Levin, Gil’manov.
AND INDUSTRIAL INORGANIC CHEMISTRY
Formation of the Morphology of Continuous-Precipitation
Aluminum Hydroxides in the Course of Industrial Synthesis
A. A. Lamberov, A. G. Aptikasheva, S. R. Egorova, O. V. Levin, and Kh. Kh. Gil’manov
Kazan State University, Kazan, Tatarstan, Russia
Yukos RM Engineering Center Private Joint-Stock Company, Russia
Nizhnekamskneftekhim Open Joint-Stock Company, Nizhnekamsk, Russia
Received August 26, 2004
Abstract-X-ray phase and differential thermal analyses were used to study in detail how the morphology
of aluminum hydroxides changes in separate stages of the technological process. The assumption that two
pseudoboehmite modifications differing in crystallite dimensions and lattice constants can be formed in
the course of precipitation was considered.
The effectiveness of catalytic systems based on
largely depends on their morphological struc-
ture, which affects a number of important characteris-
tics of the support: specific surface area, porometric
volume, pore size distribution, etc. . Active alumina
is for the most part industrially produced by thermal
decomposition of aluminum hydroxide , which in-
herits the texture of the precursor because of the pseu-
domorphism in calcination. In turn, the texture of
the precursor is determined by the conditions of pre-
cipitation and further technological procedures .
The influence exerted by the technological stages
of industrial synthesis of aluminum hydroxide (AH)
on the morphology of the active alumina obtained
gas been insufficiently covered in the literature.
Previously, the transformation of the porous struc-
ture of AH synthesized under industrial conditions by
the double-flow sulfate technology based on periodic
precipitation upon mixing of low- and high-tempera-
ture hydroxides has been studied [4, 5]. It was estab-
lished that the way in which the texture characteristics
of the mixed hydroxide are formed is primarily deter-
mined by properties of individual hydroxides, type
of interaction between particles, and transformation
of the porous structure in all stages of the technolog-
It should also be noted that, in the course of indus-
trial synthesis, AH passes a number of stages, each
making its own contribution to the texturing of alumi-
num hydroxide in precipitation and of the resulting
oxide in calcination . At the same time, it was
demonstrated in  that the texture of the system
being synthesized is mainly formed in the precipita-
tion stage. This texture can be controlled by varying
the conditions in which the process occurs.
The aim of this study was to analyze in detail the
influence exerted by factors associated with separate
stages of synthesis on the formation of AH manufac-
tured by continuous precipitation by the nitrate tech-
nology used at Novokuibyshev Plant of Catalysts Ltd.
The object of study was AH synthesized by con-
tinuous reprecipitation of alumina trihydrate by the
nitrate method. The samples to be examined were se-
lected after the following stages of synthesis: (1) pre-
cipitation at 32oC and pH 8.6; (2) stabilization at
102oC, pH 5.0, t = 90 min; (3) bringing the pH to
8.9, T =80oC, t = 130 min; (4) stabilization at 80oC,
pH 8.8, t = 4 h; (5) agitation; (6) pressing on a filter
press; (7) repulpation; and (8) bringing the pH to 9.2.
Differential thermal analysis was performed with
a Q-1500D derivatograph in air in the temperature
range 2031000oC at a heating rate of 10 deg min
the sample mass was 200 mg. The accuracy of deter-
mining the loss of mass was +0.5%.
X-ray diffraction patterns were measured on a
DRON-2 instrument (Fe
radiation, beta filter, 2q =
5o3100o, 30 kV, 15 mA). Annealed copper foil was
used as reference for determining the dimensions of