1070-4272/02/7511-1883$27.00C2002 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 75, No. 11, 2002, pp. 1883!1884. Translated from Zhurnal Prikladnoi Khimii, Vol. 75, No. 11,
2002, pp. 1920!1921.
Original Russian Text Copyright + 2002 by Moiseeva, Kurylev, Pomerantsev, Tubolkin.
Catalyst for Melamine Production
I. D. Moiseeva, A. Yu. Kurylev, V. M. Pomerantsev, and A. F. Tubolkin
Novomoskovsk Institute, Mendeleev Russian University of Chemical Engineering, Novomoskovsk,
Tula oblast, Russia
St. Petersburg State Technological Institute, St. Petersburg, Russia
Received February 5, 2002
Abstract-A novel electrolytic method for preparing the catalyst (active aluminum oxide) for melamine
synthesis and a process for catalytic synthesis of melamine from urea are proposed.
Melamine (1,3,5-triamino-2,4,6-triazine) is a valu-
able precursor in production of plastics, lacquers, and
adhesives exhibiting high mechanical strength, sta-
bility in hot water and in organic solvents, low elec-
trical conductivity, and high thermal stability. These
materials based on melamine3formaldehyde resin are
widely used in various branches of industry [1, 2].
To synthesize melamine from urea, we developed a
catalyst, active aluminum oxide with the specific sur-
face of about 3003400 m
A goal of this work was to develop a low-waste
procedure for preparing the catalyst, by ensuring
stable conditions of granule formation and improved
quality of the target product.
We improved a process for production of Al(OH)
to increase the melamine content in the
target product from 80 to 96398%. Initially we took
commercial aluminum hydroxide with the specific sur-
face area of 803120 m
. Impurities present in it
(up to 0.1 wt % Na
O, 0.1 SiO
, and 0.4 Fe
adversely affected the quality of the g-Al
(the melamine yield was about 80%). To remove
them, commercial aluminum hydroxide was reprecipi-
tated from chemically pure grade HNO
, washed to
remove ammonia, molded, dried, and calcined. The
thus prepared g-Al
provided the melamine yield of
up to 88.5% and had the specific surface area of 1603
, which is insufficient for commercial pro-
duction of melamine.
Nevertheless, the above study showed that purifica-
tion of alumina increases the process selectivity.
However, the above purification procedure is unaccep-
table, because the increase in the number of reprecipi-
tation stages complicates the technology and increases
the washwater amount. Therefore, we developed a
method for preparing Al(OH)
from pure metallic
aluminum by electrolytic precipitation. The precipitate
was molded in grains by a sol3gel process and then
was thermally treated to obtain granulated g-Al
Two electrodes (200 0 120 0 15-mm plates) made
from metallic aluminum (99.9 wt % Al) were placed
parallel to each other at a distance of 10315 cm in a
glass vessel filled with distilled water containing 23
as an electrolyte; dc electrolysis was
performed at I = 27 A and U =65V.
A gel-like Al(OH)
precipitate was formed on the
anode. The pulp was separated at the solid : liquid
ratio of 1 : 8 by centrifuging, and a substance with the
solid : liquid ratio of 1 : 4 and pH 7 was obtained.
Concentrated chemically pure grade HCl was added to
decrease pH to 334. A transparent thixotropic colloid
of basic aluminum chloride (BAC) was thus obtained
by the reaction 
+ HCl 6 Al
Cl + H
with the Al
content of 50 g dm
; it was aged at
room temperature for 12324 h.
A drop-oil method was used to mold granules.
A molding mass was poured in a cone-shaped vessel
and fed through a pipette 1.5 mm in diameter at a rate
of 233 drops s
into a molder, a cylinder filled with
a two-phase liquid (334-cm layer of kerosene to form
drops and 25% aqueous solution of urea to form three-
dimensional gel structure; the layer thick was suf-
ficient for neutralization of granules for 33 4 min).
In the first stage, granules were dried for 1 day in air.
In the second stage, they were dried in a vacuum drier
for 233 days at 40oC. Then the temperature was ele-
vated at a 10 deg h
rate to 150oC, and at this tem-