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SULIMOV et al.
Fourier IR spectrometer from KBr pellets in the range
400–4000 cm–1. The results obtained are well consistent
with published data [8].
in the process, to propylene epoxidation. The combination
of the processes will reduce the cost of propylene
oxide production by reducing the expenditures for the
isolation of hydrogen peroxide produced by oxidation
of isopropanol.
The catalyst sample morphology was characterized
by taking micrographs with a Hitachi S-2500 scanning
electron microscope equipped with a JNCA attachment
for energy-dispersive X-ray microanalysis (Oxford).
From the data obtained, the mean particle size was
determined; it appeared to be 236 nm.
The physicochemical relationships of the epoxidation
processes were studied both in methanol and in isopropyl
alcohol (only in the case of using propylene). Along
with the kind of the solvent [6], the epoxidation process
is significantly influenced by other factors such as
solvent concentration, reactant ratio, temperature, etc.
Here we report the results of an experimental study of
the influence exerted by these parameters on the liquid-
phase epoxidation of unsaturated organic substrates with
hydrogen peroxide in the presence of powdered titanium
silicalite.
The specific surface area, total pore volume, and
distribution of the pore volume with respect to the
pore size were determined for the synthesized titanium
silicalite with a TriStar 3020 automatic gas-adsorption
analyzer (Micromeritics). From the data obtained, the
following parameters of the pore structure of the catalyst
were calculated in the automatic mode: specific surface
area 316.66 m2 g–1, pore volume 0.182 cm3 g–1, and pore
size in the distribution maximum 32–45 Å. The Ti content
(counting on TiO2) was 3.16%, and the Si/Ti ratio was 25.
EXPERIMENTAL
The following chemicals were used in the study:
methanol, analytically pure grade, GOST (State
Standard) 2222–95; propylene, GOST 25043–87; allyl
chloride, TU (Technical Specification) 6-01-753–77;
allyl alcohol, TU ТУ 6-01-753–77, 33–34% hydrogen
peroxide, ultrapure grade, TU 2611-069-05807977–2006;
tetrabutoxytitanium, TU 6-09-2738–89; tetraethoxysilane,
TU 2435-41905763441–2003; tetrapropylammonium
hydroxide prepared by passing tetrapropylammonium
bromide (98%, Acros) through anion-exchange resin
(Dowex MSA-1 C).
The epoxidation of the organic substrate was
studied on a laboratory batch reactor equipped with an
electromagnetic stirrer and a system for maintaining a
constant temperature. The reactor was charged with a
calculated amount of the organic substrate, solvent, and
catalyst.After that, the magnetic stirrer drive was switched
on, the reactor was connected to a thermostat, and the
mixture was thermostated for 10–15 min to attain the
preset temperature. Then, hydrogen peroxide was added,
and the time of the reaction start was fixed. In synthesis
of propylene oxide, the propylene pressure in the system
was maintained in the interval 5–7 atm. Synthesis of
epichlorohydrin was performed under a nitrogen pressure
of 2.5–3.5 atm to keep the components in the liquid
state. Glydidol was synthesized at atmospheric pressure.
After definite time intervals, samples were taken with a
capillary for analysis.
The catalyst, titanium-containing zeolite, was
prepared by the procedure described in a patent [7].
The catalyst synthesis was performed in an autoclave
mounted on a rocker performing back-and-forth motion
(amplitude 0.05 m) at a rate of 2 s–1. The synthesis was
performed at 170°С for 40 h with stirring. After cooling
the resulting suspension of titanium silicalite, the solid
was washed with water to pH 7–8, dried for 12 h at 120°С
in a vacuum (20 mmHg), and calcined at 550°С for 6 h
in a muffle furnace.
The reaction mixture components were analyzed by
gas chromatography with a Khromos GKh-1000 device
equipped with a flame ionization detector. A metal
column (2 m × 3 mm) was packed with Chromaton
N-AW onto which 15 wt % Carbowax 6000 was applied.
The carrier gas was nitrogen (flow rate through the
column 50 mL min–1. The temperatures of the column
vaporizer and thermostat were kept at 180 and 130°С,
respectively. The detector temperature was 200°С.
The reaction mixture composition was determined by
absolute calibration. The amount of hydrogen peroxide
was determined by iodometric titration. Five to seven
To determine the structure of the synthesized titanium
silicalite, we performed its X-ray diffraction analysis and
recorded the IR spectra. The powder X-ray diffraction
analysis was performed on a Shimadzu Lab XRD6000
diffractometer (CuKα radiation, nickel filter, scintillation
counter, voltage 30 kV, current 30 mA) in the angle range
2θ = 10°–80°. The IR spectra of titanium silicalite were
recorded in air at room temperature with an IRAffinity-1
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 88 No. 1 2015