192
MIKHAILOVSKAYA et al.
and ammonia, one can control the selectivity of ammonia
liquid phase, 15% tetraoxyethylhexamethylenediamine
on a solid support, Chromaton (0.2–0.25 mm), at 36°C.
oxidation by providing predominant formation of N O
2
as the main reaction product [4].
The content of N O was determined on a column (l =
2
1
.5 m) with Porapak Q at 30°C.
The goal of our study was to examine the influence
exerted by the content of tin dioxide on the catalytic
properties of mixed vanadium–titanium–tin catalysts
in oxidative ammonolysis of 3- and 4-methylpyridines
and on the selectivity of transfer of ammonia’s nitrogen
atom to the CN group.
Inthisstudy, weexaminedtheoxidativeammonolysis
of 3- and 4-methylpyridines on V–Ti–Sn–O catalysts of
various compositions at V O : TiO : SnO ratios of 1 :
4 : 1, 1 : 4 : 4, and 1 : 4 : 8, which contained 23.1, 54.6,
2
5
2
2
and 70.6 wt % SnO , respectively. A test of a V–Ti–
2
Sn–O catalyst of 1 : 4 : 8 composition with 70.6 wt %
EXPERIMENTAL
SnO in oxidative ammonolysis of 4-methylpyridine
2
demonstrated that, with the reaction temperature raised
On being dried and distilled, the starting
methylpyridines of pure grade had characteristics of
individual substances: 3-methylpyridine, bp 142°C/690
mm Hg, d420 0.9566, nD 1.5058; 4-methylpyridine,
from 230 to 290°C at a 4-methylpyridine : O : NH3
2
ratio of 1 : 37 : 3, the conversion of 4-methylpyridine
changes from 60 to 100%. The yield of the main reaction
product, 4-cyanopyridine, is 42% at 230°C, but, as the
temperature is raised, reaches a value of 85% at 290°C.
The conversion selectivity of 4-methylpyridine to
20
bp 141°C/695 mm Hg, d4 0.9547, n D2 0 1.5058. These
20
parameters were in agreement with reference data.
4
-cyanopyridine under these conditions is 85%.
Vanadium–titanium–tin catalysts were prepared
from vanadium(V) and tin(IV) oxides and metatitanic
acid (H TiO ). Metatitanic acid was taken in such an
One of the most important factors for the reaction
of oxidative ammonolysis of 4-methylpyridine is its
selectivity with respect to ammonia. Use of excess
amounts of ammonia delivered into the reaction zone
leads to an increase in the amount of an unreacted
reagent in reaction gases and diminishes the selectivity
of transfer of ammonia’s nitrogen atom to the nitrile
group. Therefore, we carried out experiments with
various rates of ammonia supply into the reaction zone
at 4-methylpyridine : O : NH molar ratios of 1 : 20 :
2
3
amount that the catalyst formed upon its decomposition
by the equation H TiO → TiO + H O contained the
2
3
2
2
necessary amount of titanium dioxide. The starting
substances were mixed in V O : TiO : SnO molar
2
5
2
2
ratios of 1 : 4 : 1, 1 : 4 : 4, and 1 : 4 : 8, and then grains
were formed from the resulting stock by compaction or
rubbing a humidified mass into a perforated plate, dried
in air, and calcined at 350°C for 3 h.
2
3
The oxidative ammonolysis of 3- and 4-methylpyri-
dines was performed in a flow-through reactor with
a stainless steel reaction tube 20 mm in diameter and
(1.2–3.0). It was found that, with 3 moles of ammonia,
its conversion at 230°C is 75%. With the temperature
raised to 290°C, it increases to 98%. The selectivity of
transfer of ammonia’s nitrogen atom to the nitrile group
of isonicotinic acid at 290°C does not exceed 25–30%.
As the amount of ammonia delivered to the reaction is
lowered to 1.2 mol per mole of 4-methylpyridine, the
conversion of ammonia was 90–94% and the selectivity
of transfer of ammonia’s nitrogen atom to the nitrile
group increased to 55–67%.
1
000 mm long. The reactor was charged with 100 ml of
a granulated catalyst.
The unreacted 3- and 4-methylpyridines and
products of their oxidative ammonolysis were caught
with water in airlift scrubbers and analyzed by gas-
liquid chromatography.
Ammonia and products of its oxidation contained in
reactiongasesformedinoxidativeammonolysisof 3-and
A study of the oxidative ammonolysis of 4-methyl-
pyridine on another sample of the V–Ti–Sn–O catalyst
4
-methylpyridines on V–Ti–Sn–O catalysts of various
compositions were determined by chromatography
containing 54.6% SnO demonstrated that, with 2–3 mol
2
–
1
at the following flow rates: starting substance 52 g l
of ammonia per mole of methylpyridine, raising the
reaction temperature to above 290°C leads to a sharp
decrease in the yield of 4-cyanopyridine on this catalyst.
The conversion of ammonia at this temperature is 100%.
–
1
of the catalyst per hour, air 2.0 l min , and ammonia
–1
0
8
.06 l min , at a temperature of 290°C. LKhM-
chromatographs with heat-conductivity detectors
were used in the study. Ammonia was quantitatively
N O was found in reaction gases, with its yield on this
2
determined on a column (l = 3 m, d = 3mm) filled with a
catalyst at 290°C and 3 mol of ammonia delivered per
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 85 No. 2 2012