Influence of rhenium additives on the activity of Cu/sibunite catalyst in transformations of isopropyl alcohol

Article abstract of DOI:10.1023/A:1021332428586

The dehydrogenating and dehydrating properties of the Cu(2%)/sibunite catalyst with rhenium additives were studied in the transformations of isopropyl alcohol at 200-270°C. The catalyst containing 0.25% Re was found to possess the maximum dehydrogenating activity at 200°C.

Full text of DOI:10.1023/A:1021332428586

1768
Russian Chemical Bulletin, International Edition, Vol. 51, No. 9, pp. 1768—1770, September, 2002
Influence of rhenium additives on the activity of Сu/sibunite catalyst
in transformations of isopropyl alcohol
M. A. Ryashentseva
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences,
47 Leninsky prosp., 119991 Moscow, Russian Federation.
Fax: +7 (095) 135 5328. Еꢀmail: secretary@ioc.ac.ru
The dehydrogenating and dehydrating properties of the Cu(2%)/sibunite catalyst with
rhenium additives were studied in the transformations of isopropyl alcohol at 200—270 °С.
The catalyst containing 0.25% Re was found to possess the maximum dehydrogenating
activity at 200 °C.
Key words: supported copperꢀ and rhenium,copperꢀcontaining catalysts, dehydrogenaꢀ
tion, dehydration, isopropyl alcohol, acetone, propylene, sibunite.
It has previously1 been found that the introduction
of the 1% Re additive enhances the activity of the
Cu(1%)/Sib catalyst (Sib is sibunite) in the transformaꢀ
tion of isopropyl alcohol into acetone, and low Cu,Re/Sib
catalysts are active in the selective dehydrogenation of
methanol to methyl formate (MF).2 The addition of
0.25% Re favors an increase in the dehydrogenating acꢀ
tivity and stability of the Cu(4%)/Sib catalyst.
In this work, the possibility to enhance the dehydroꢀ
genating activity of the Cu/Sib catalyst in the decompoꢀ
sition of isopropyl alcohol by rhenium additives was exꢀ
plored.
dried at 120 °С before experiments and then reduced in a
hydrogen flow at 400 °С. Six samples containing 2% Cu were
prepared: one sample without an additive (1), four samples
with an additive of Re (0.25, 0.5, 1.0, and 2.0%) (2—5), and
one sample with the Cu(2%)+Re(0.25%)/Sib composition (6).
For the preparation of sample 6, the support was impregnated
with copper nitrate instead of acetate. The degree of converꢀ
sion of isopropyl alcohol was taken as a measure of catalytic
activity. Selectivity was determined from the fractions of acꢀ
etone and water in the liquid catalyst.
Results and Discussion
The results illustrating the catalytic properties of
samples 1—6 are presented in Table 1. The liquid prodꢀ
ucts of isopropyl alcohol transformation on the monoꢀ
metallic (no rhenium) catalyst contain acetone and waꢀ
ter along with the unreacted alcohol, and the gaseous
products contain propylene and hydrogen. Two reacꢀ
tions occur under the chosen conditions at 200 °С: deꢀ
hydrogenation to form acetone and hydrogen (1) and
dehydration to form propylene and water (2).
Experimental
The reaction was studied under the atmospheric pressure in
a flowꢀtype set with a quartz reactor (350×20 mm). The weight
of the catalyst sample was 1.35 g. Isopropyl alcohol (reagent
20
20
grade) (nD 1.3776, d4 0.7854) was supplied into the reactor
using an automated plungerꢀtype dosing system with a space
velocity of 1.1 h–1 in a hydrogen flow. Experiments were carꢀ
ried out at temperatures of 200, 235, 250, and 270 °С using the
same portion of the catalyst in each experiment. The duration
of each experiment was 30 min. Liquid products were analyzed
by GLC (column 3 m×3 mm packed with 15% polyethylene
glycol adipinate on Chromosorb P) and by refractometry. For
analysis of gaseous products, a column (2 m×3 mm) packed
with Polisorb was used. Sibunite (granular pyrocarbon with a
filled mass of 0.6 g cm–3) served as the support for the catalyst.
Its specific surface measured by nitrogen adsorption was
680 m2 g–1, and that measured by phenol adsorption was
230 m2 g–1. The granular size of the support was 2—3 mm.
Catalysts were prepared by the impregnation of sibunite
with solutions of NH4ReO4 and copper acetate. Samples were
Cat. is catalyst
The total conversion of the alcohol is 15.3%, and the
acetone : water ratio is equal to 3.3. When the temperaꢀ
ture increases from 200 to 270 °С, the total conversion
of the alcohol on the monometallic catalyst increases
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1622—1623, September, 2002.
1066ꢀ5285/02/5109ꢀ1768 $27.00 © 2002 Plenum Publishing Corporation

Activity of Cu,Re/sibunite
Russ.Chem.Bull., Int.Ed., Vol. 51, No. 9, September, 2002
1769
Table 1. Transformation of isopropyl alcohol on catalysts 1—6
Cataꢀ
lyst
Conꢀ
tent of Re
(%)
Т
/°С
Composition of liquid
products (wt.%)
Total
conversion
(mol.%)
Conversion
(mol.%) to
Selectivity of transꢀ Acetone :
formation of PriOH
water
Me2CO H2O
PriOH
Me2CO H2O
Me2CO H2O
1
0
200
235
250
270
200*
200
235
250
270
200
235
250
270
200
235
250
270
200
235
250
270
200*
200
235
250
275
200*
11.6
28.6
33.6
37.7
10.1
18.2
39.2
45.1
56.4
23.9
46.8
49.7
57.3
23.0
37.3
45.1
53.6
35.1
51.0
59.2
65.4
43.5
48.4
73.2
78.9
80.5
38.3
1.1
1.8
1.7
1.8
1.1
1.0
1.7
2.4
2.8
2.0
2.4
2.2
2.4
2.6
3.6
3.6
4.1
3.1
7.2
8.9
9.7
3.4
3.2
4.6
3.4
6.4
2.4
87.3
69.6
64.7
60.5
88.8
80.8
59.1
52.5
40.8
75.1
50.8
48.1
40.3
74.4
59.1
51.3
42.3
61.8
41.8
31.9
24.9
53.1
48.4
22.2
17.7
13.1
59.3
15.3
33.8
38.4
42.7
14.0
21.5
43.9
51.1
62.4
29.4
52.6
54.8
62.6
30.4
46.1
51.5
62.0
43.3
64.8
71.8
80.1
51.5
55.7
80.3
85.2
89.0
44.5
11.7
28.1
33.0
37.0
10.4
18.3
38.6
43.6
53.8
23.1
45.2
47.9
55.2
22.3
35.2
39.5
49.8
33.9
44.5
50.0
54.2
41.1
46.1
66.8
74.1
71.0
36.8
3.6
5.7
5.4
5.7
3.6
3.2
5.3
7.5
8.6
6.3
7.4
6.9
7.4
76.6
83.1
86.0
86.7
74.5
85.0
87.8
85.4
86.3
78.6
85.9
87.4
88.1
73.3
76.0
76.0
80.3
78.3
68.7
67.5
67.6
79.9
82.7
83.3
87.0
79.7
82.6
23.4
16.9
14.0
13.3
25.5
15.0
12.2
14.6
13.7
21.4
14.1
12.6
11.9
26.7
24.0
24.0
19.7
21.7
31.3
32.3
32.4
20.1
17.3
16.7
13.0
20.3
17.4
3.3
4.9
6.7
6.5
3.0
5.7
7.1
5.8
6.3
3.6
6.0
6.9
7.4
2.7
3.0
3.0
4.1
3.6
2.2
2.1
2.1
3.9
4.8
4.9
6.7
3.9
4.8
2
3
4
5
0.25
0.5
1.0
8.1
10.9
12.0
12.2
9.4
20.3
24.2
25.9
10.4
9.6
13.5
11.1
18.0
7.7
2.0
6**
0.25
* After the operation of the catalyst for 2 h at higher temperatures. In other cases, data were obtained 30 min after the
beginning of experiment.
** Catalyst prepared from copper nitrate.
from 15.3 to 42.7% and the selectivity for acetone forꢀ
mation increases from 76.6 to 86.7%. Correspondingly,
the acetone : water ratio increases from 3.3 to 6.7. An
initial activity of the Cu(2%)/Sib catalyst 200 °С was
nearly completely restored when the temperature of the
sample operated at 270 °С for 2 h was finally reduced
to 200 °C.
The introduction of rhenium additives enhances the
activity of the catalyst. The total conversion of the alcoꢀ
hol at 200 °С increases from 15.3% on monometallic Cu
catalyst 1 to 43.3% on sample 5 with 2.0% Re. The
maximum increase in the dehydrogenating activity is obꢀ
served for the rhenium content 0.25% (samples 2 and 6).
The acetone : water ratio increases on these catalysts to
5.7 and 4.8, respectively.
When the temperature increases from 200 to 270 °С,
the total conversion of the alcohol on the most active
catalyst 5 (Cu(2%)+Re(2%)/Sib) increases from 43.3 to
80.1%. However, its dehydrogenating activity decreases,
while the dehydrating activity increases: the selectivity
with respect to acetone decreases and that for water (proꢀ
pylene) increases. On this catalyst, as on the sample
containing 0.25% Re, the ratio of the products of reacꢀ
tions (1) and (2) typical of the catalyst operated at
200 °С is completely restored when an operating temꢀ
perature in excess of 200 °С after 2ꢀh timeꢀon stream is
reduced to 200 °С. This implies, evidently, that the low
(Cu,Re)/Sib catalysts do not loose their activity during
alcohol transformation due to the presence of such reꢀ
ducing agents as Н2 and Н2О in the reaction mixture.
They prevent the deposition of coke or other deactivatꢀ
ing products on the catalyst surface.
Catalyst 2 also exhibits2 the maximum activity and
selectivity for the dehydrogenation of methanol to MF.
An increase in the rhenium content noticeably changes
the direction of PriOH transformation.
Rhenium, being a metal with a comparatively high
melting point, does not undergo recrystallization during

1770
Russ.Chem.Bull., Int.Ed., Vol. 51, No. 9, September, 2002
M. A. Ryashentseva
2. M. A. Ryashentseva, E. V. Egorova, A. I. Trusov, and S. N.
Antonyuk, Izv. Akad. Nauk, Ser. Khim., 2002, 1559 [Russ.
Chem. Bull., Int. Ed., 2002, 51, 1698].
3. M. A. Ryashentseva and Kh. M. Minachev, Renii i ego
soedineniya v geterogennom katalize [Rhenium and Its Comꢀ
pounds in Heterogeneous Catalysis], Nauka, Moscow, 1983,
247 pp. (in Russian).
4. Kh. M. Minachev, M. A. Ryashentseva, and Yu. A.
Afanas´eva, Neftekhimiya, 1961, 1, 482 [Petroleum Chem.,
1961, 1 (Engl. Transl.)].
5. US Pat. 3415737; RZhKhim. [Abstract J. of Chemistry], 1970,
211151P (in Russian).
catalysis and, therefore, favors an increase in the stabilꢀ
ity of the metalꢀsupported catalyst.3 This fact has first4
been demonstrated for the bimetallic (Pd,Re)/Al2O3 and
(Pt,Re)/Al2O3 catalysts for reforming (see Refs. 5—7).
The present work shows that the rhenium additive imꢀ
proves the dehydrogenating properties of the Cu(2%)/Sib
catalyst.
Thus, the introduction of rhenium into the carbonꢀ
supported copper catalysts allows the purposeful change
in the selectivity of isopropyl alcohol transformation.
6. M. A. Ryashentseva, Neftekhimiya, 1999, 39, 48 [Petroleum
Chem., 1999, 39, 45 (Engl. Transl.)].
References
7. M. A. Ryashentseva, Neftekhimiya, 2001, 41, 17 [Petroleum
Chem., 2001, 41, 14 (Engl. Transl.)].
1. M. A. Ryashentseva, Izv. Akad. Nauk, Ser. Khim., 1998,
2381 [Russ. Chem. Bull., 1998, 47, 2309 (Engl. Transl.)].
Received March 12, 2002