CATALYTIC SYNTHESIS OF CUMENE FROM BENZENE AND ACETONE
21
EXPERIMENTAL
absorbed with the sample was measured with a thermal
conductivity detector.
Benzene hydroalkylation with acetone was examꢀ
ined in a flow reactor. Prior to running the reaction,
As the zeolite catalyst component, the following
commercially available zeolites manufactured by
Zeolyst were used: MFI (SiO2/Al2O3 = 23), BEA
the catalyst was activated in a hydrogen flow at 300
for 3 h. The catalytic reaction was carried out in the
gas–liquid mode with nitrogen dilution (15 mL/min)
of the reaction mixture at a temperature range within
135–300 , pressures of 0.1 to 3 MPa, a feed mass
°С
(
SiO2/Al2O3 = 25), MOR (SiO2/Al2O3 = 13), and
FAU(Y) (SiO2/Al2O3 = 30). To prepare the H forms of
zeolites, the NH4 forms of samples were calcined in a
dry air flow at 550 for 6 h.
3
°
С
°
C
The hydrogenating catalyst component was preꢀ
pared according to the previously developed proceꢀ
dure: hot solutions of copper nitrate (16.1 g) in water
(50 mL) and ammonium chromate (7.6 g) in water
(50 mL) were poured gradually and simultaneously to
distilled water (100 mL). The solution was left stirring
flow rate of 2–4 g/(g·h), and a benzene : acetone :
hydrogen molar ratio of (4–9 : 1) : 1.2. The products
were analyzed by GLC on a Kristall 2000M chromatoꢀ
graph, equipped with a flame ionization detector and
a SEꢀ30ꢀcoated quartz capillary column, and by the
GC–MS technique on a Thermo DSQꢀII mass specꢀ
trometer combined with a Trace GC gas chromatoꢀ
graph equipped with a quartz capillary column coated
with the DBꢀ5 phase. The catalytic properties of the
catalysts were evaluated by measuring the acetone
conversion, the selectivity, and the cumene yield.
at 70
washed with distilled water until the filtrate was transꢀ
parent, dried at 100 for 15 h, and then calcined at
550 for 3 h.
°С for 20 min. The precipitate was filtered off,
°С
°С
The bifunctional catalyst composed of the hydroꢀ
genating component and the alkylating component
was prepared by mixing the hydrogenating component
(10 wt %) and zeolite (90 wt %), thorough triturating
the mixture in a mortar, pelletizing the mass, crushing
the pellets, and taking the fraction of 0.5–1.0 mm. The
samples obtained were denoted as CuCr2O4
CuO/zeolite type, for example, CuCr2O4 · CuO/BEA.
The chemical composition of zeolites was deterꢀ
mined by atomic absorption spectroscopy. Lowꢀtemꢀ
perature nitrogen adsorption isotherms were taken on
an ASAP2000 automatic porosimeter (Micromeritics,
USA). The pore volume was calculated from
RESULTS AND DISCUSSION
Physicochemical Characteristics
of the Hydrogenating Component
·
According to the XRD data (Fig. 1), the syntheꢀ
sized sample of the hydrogenating component is an
almost equimolecular mixture of copper chromite and
copper oxide, a composition that is consistent with
chemical reactions that have to proceed during synꢀ
thesis:
the amount of sorbed nitrogen at a relative pressure of Cu(NO3)2 + (NH4)2CrO4
p/p0 = 0.95. The micropore volume was determined
using the tꢀplot method.
→
CuCrO4 + 2NH4NO3,
(
a
)
t
2CuCrO4
(
a
)
CuCr O CuO (b) + 1.5О2.
·
4
⎯⎯→
2
The reducing and acid properties of the component
were evaluated by the TPR H2 and TPD NH3 methꢀ
ods. The TPR Н2 spectrum is in good agreement with
published data [27]. Note that the experimentally
determined amount of hydrogen (8.0 mmol/g)
absorbed by the sample practically is the same as the
theoretically possible amount (8.6 mmol/g) required
for reduction of all copper cations to the metal.
The Xꢀray diffraction patterns were recorded on a
DRONꢀ3M diffractometer (CuK
α
radiation) within
the angle range of 5 < < 80.
2
θ
Acid properties of the samples were studied using
temperatureꢀprogrammed desorption of ammonia
(TPD NH3). The sample was calcined in a dry air flow,
then in a dry helium flow, and cooled to room temperꢀ
ature. Ammonia was diluted with nitrogen (1 : 1) and
adsorbed for 30 min at room temperature. The physiꢀ
cally adsorbed ammonia was blown out in a dry helium
The study of the acid properties of the hydrogenatꢀ
ing component showed that the sample contained a
small quantity of acid sites: the amount of NH3 desꢀ
flow at 100
for the hydrogenating component. The TPD NH3
experiments were conducted within the temperature
range of 25– 800 in a dry helium stream (flow rate
of 30 mL/min) using a heating rate of C/min.
°
С for 1 h for zeolites or at 50°С for 15 min
orbed from the sample was 40 mol/g.
µ
°
С
Physicochemical Characteristics of Zeolites
8
°
The physicochemical characteristics of zeolites
studied in this work are given in Table 1. Zeolites of
various structural types with close Si/Al ratios: MOR,
FAU(Y), BEA, and MFI were used in the study.
Mordenite (MOR) has a pseudoꢀoneꢀdimensional
The redox properties of the hydrogenating compoꢀ
nent were examined by the method of temperatureꢀ
programmed reduction with hydrogen (TPR H2). The
sample was pretreated at 500°С for 1 h in an argon
flow, then cooled to room temperature in an argon
flow. Then the sample was held for 40 min at room
temperature in a mixed stream containing 3.5% of
hydrogen in argon. Then, the temperature was raised
structure with a channel diameter up to
7 Å, whereas
beta (BEA), faujasite (FAU), and MFI have threeꢀ
dimensional structures with a channel diameter of
7.7 Å (BEA), 5.5 Å (MFI), or 7.4 Å with 12 Å cavities
to 700
°
С
at a heating rate of
8 C/min. The change in
°
thermal conductivity of a gas flow when hydrogen was (FAU(Y)).
PETROLEUM CHEMISTRY Vol. 53
No. 1
2013