6
74
KARAKHANOV et al.
Ammonium thiomolybdate (NH ) MoS was pre-
Table 1. Concentrations of elements in the catalysts, at %
4
2
4
pared as described in [30].
The synthesis
Sample
C 1s O 1s Mo 3d Ni 2p3 S 2p
procedure
for
MPF–NiMoS-1
MPF–NiMoS-2
62.0 25.4
37.6 34.6
2.7
4.8
1.1
2.6
6.2
15.2
[
(n-Bu) N] Ni(MoS ) was similar to that described
4 2 4 2
in [24]. According to the procedure, 6.92 g of tetrabu-
tylammonium bromide in 10 mL of CH CN was
3
added to a solution of 0.68 g of NiCl · 6H O in a min-
2
2
ordered mesopores and a high specific surface area
and provide the possibility of modifying their surface
with functional groups [26–28]. The precursor was
synthesized by impregnating the support with a tetra-
butylammonium nickel–tetrathiomolybdenum com-
plex. The catalytic activity in hydrogenation was stud-
ied using naphthalene and methylnaphthalenes as
model substrates.
imum amount of water under stirring. After that,
2
.00 g of (NH )MoS in 10 mL of a H O–CH CN
4 4 2 3
mixture (component volume ratio of 1 : 1) was added
dropwise to the resulting solution. The resulting
maroon precipitate [(n-Bu) N] Ni(MoS ) was fil-
4
2
4 2
tered off, washed with isopropyl alcohol, and air-
dried. The yield of the complex was 2.65 g; according
to elemental analysis, the Mo and Ni contents were
19.87 and 6.34%, respectively.
EXPERIMENTAL
The MPF–NiMoS precursor was synthesized as
follows: 2.00 g of [(n-Bu) N] Ni(MoS ) was dissolved
4
2
4 2
in 200 mL of THF, 1.960 g of the MPF support was
added with stirring, and the resulting solution was fur-
ther stirred at room temperature for 12 h. The solvent
was evaporated on a rotary evaporator. The synthe-
Materials
The reactants were triblock copolymer Pluronic
F127 (M = 12600, EO PO EO , Aldrich); phenol
n
106
70
106
(
(
chemically pure grade, Reakhim); formaldehyde sized MPF–NiMoS sample was a black powder with a
37% aqueous solution, Sigma-Aldrich); sodium yield of 3.920 g.
hydroxide (reagent grade, Irea 2000); hydrochloric
acid (reagent grade, Irea 2000); ammonium molyb-
date (analytical grade); nickel(II) chloride hexahy-
drate; an ammonia aqueous solution (analytical
grade); tetrabutylammonium bromide (analytical
grade, Sigma-Aldrich); dimethyl disulfide (DMDS)
Hydrogenation
Catalytic hydrogenation tests were conducted in a
steel autoclave at a high hydrogen pressure with vigor-
ous stirring of the reaction mixture. A calculated
amount of MPF–NiMoS and 2 mL of a 10% substrate
solution in n-hexadecane were placed in the autoclave.
If required by the test conditions, 70 μL of DMDS was
(
≥99%, Aldrich); naphthalene (97%, Aldrich);
-methylnaphthalene (95%, Aldrich); and 2-methyl-
naphthalene (97%, Aldrich).
1
The solvents were methanol (99+%, Acros Organ- added to the reaction mixture. The autoclave was filled
ics); ethanol (analytical grade, Irea 2000); isopropanol with hydrogen to a pressure of 5.0 MPa at room tem-
(
analytical grade, Irea 2000); chloroform (Purum, perature and placed in an oven preheated to 380°C for
Ecos-1); and acetonitrile (reagent grade, Khimmed).
5 h. The hydrogenation products were analyzed on a
Krystallyuks 4000 M chromatograph equipped with a
flame-ionization detector and a Petrocol DH 50.2
capillary column coated with the polydimethylsilox-
Equipment and Methods
Nitrogen adsorption/desorption isotherms were ane stationary liquid phase (dimensions, 50 m ×
recorded at a temperature of 77 K on a Gemini VII 0.25 mm; carrier gas, helium; split ratio, 1 : 90).
2
390 instrument. X-ray photoelectron microscopy
(
XPS) studies were conducted on a VersaProbeII
RESULTS AND DISCUSSION
The in situ synthesized catalysts MPF–NiMoS-1
13
instrument. Solid-state C (CPMAS) NMR spectros-
copy studies were conducted on a Varian NMR Sys-
tems instrument at an operating frequency of (without sulfiding) and MPF–NiMoS-2 (sulfiding
1
25 MHz in a pulsed mode at a spinning speed of with DMDS) were studied by XPS. According to the
1
0 kHz. The metal content in the samples was deter- XPS data, all the catalysts exhibit peaks characteristic
mined by inductively coupled plasma atomic emission of molybdenum, nickel, sulfur, carbon, and oxygen.
spectroscopy (ICP-AES) on a Thermo Electron IRIS The concentrations of the elements calculated from
Interpid II XPL instrument in radial and axial viewing the survey spectra of the catalysts are listed in Table 1.
configurations at wavelengths of 310 and 95.5 nm.
The binding energies (E ) determined from the results
b
of the approximation of high-resolution spectra by the
nonlinear least-square method using the Gaussian–
Lorentzian function are listed in Table 2. In the Mo 3d
Precursor Synthesis
An FDU-15 mesoporous phenol–formaldehyde spectra (Figs. 1a, 1b), the 1–1' (228.7–229.1 eV) and
MPF) polymer was synthesized as described in [29].
(
2–2' doublets (230.0 eV) correspond to sulfides and
PETROLEUM CHEMISTRY
Vol. 57
No. 8
2017