- Email: [email protected]
Methane transformation into aromatic hydrocarbons by activation with ethane over Zn-ZSM-11 zeolite
NATURAL GAS CONVERSION V Studies in Surface Science and Catalysis, Vol. 119 A. Parmaliana et al. (Editors) o 1998 Elsevier Science B.V. All rights reserved.
M e t h a n e t r a n s f o r m a t i o n into aromatic h y d r o c a r b o n s ethane over Z n - Z S M - 1 1 zeolite
235
by activation with
Liliana B. Pierella(*), Griselda A. Eimer(+) and Oscar A. Anunziata(*) CITeQ (Centro de Investigaci6n y Tecnologia Quimica) Facultad C6rdoba, Universidad Tecnol6gica Nacional. CC 36 -SUC 16, (5016) C6rdoba, ARGENTINA. e-mail: [email protected] - an [email protected] FAX:054-51-690585 ABSTRACT Very high levels of methane (C1) conversion to aromatic hydrocarbons were obtained by interaction with ethane (C2) (molar fraction in the feed: C1/CI+C2 = 0.4-0.8) over Zn-ZSM11 (molar fraction Zn/Zn+H-0.86) at 550~ and total pressure of 1 atm. The yield in aromatic hydrocarbons was about 10-40 mol% C. I.INTRODUCTION Direct conversion of methane (C1) to more valuable compounds, such as liquid hydrocarbons is not only a promising approach for the utilization of natural gas (NG) resource but also a challenging technical project. C1 (the main compound of NG) conversion, under non-oxidizing conditions is a great task to catalysis science. Walsh et al. reported [1] the formation of aromatic-rich hydrocarbons from DPO of C 1 with 02 over ZSM5 in the presence of small amounts (0.2-0.4 mol%) of light hydrocarbons additive, such as propane (C3) or propylene (C3 =) in the feed. The reaction sequence involves DPO of C1 to methanol (C 1OH) followed by the C1OH-gasoline reaction and the hydrocarbons are comes from, alkenes or alkanes precursors present in the feed to initiate the MTG reaction. Han et al. [2,3] reported similar results showing product selectivity to COx >80% and to liquid hydrocarbons products >13%. Wada [4] reported that unpromoted rare earth oxides were active for the oxidative methylation of C2 with C 1, indicating that E u 2 0 3 - O x catalyst gave the maximum yield of C3 products under selected reaction conditions. Thus the maximum C3 compound was 8%. Recently Wang [5] and Pierella [6] reported the aromatization of C1 in the presence of small amount of light hydrocarbons under non-oxidizing conditions over Mo-Zeolite at low pressure (1-2atm). Commercial NG can contain up to 10 % of ethane (C2). Solymosi and Szoke [7] reported high ethane conversion and benzene selectivity using MoC/ZSM-5 at 700~ In this work, the activation of methane with ethane and the transformation of pure methane and pure ethane, using HZSM-11 and Zn loaded ZSM-11 zeolite, have been studied. The final objective is the transformation of NG into petroleum-chemicals products.
2.EXPERIMENTAL Catalytic reactions were carried out in a continuous flow quartz reactor with an inner diameter of 10 mm at atmospheric pressure. Products were withdrawn periodically from the (*) CONICET-Researcher; (+) CONICET Fellowship. Research Grants: PID-CONICET N~ 6963/96 and CONICOR NO3663/96.
236
outlet of the reactor and analyzed by on-line gas chromatography equipped with a FID detector. The following feeds were used in this study: high purity methane (>99.97%) ethane (>99.997%) supplied by AGA. Commercial Natural Gas (analysis: C1 = 82.8; C2 = 16.1; C3 = 0.8; C4 = 0.5 mol%) was supplied by ECO-GAS (Argentine). The studies with methane were carried out at GHSV = 2224, 820 and 590 ml/gh. For ethane GHSV = 2224 and 820ml/gh were employed and molar fraction x(C2) = 1 and x(C2) = 0.36 using N2 as diluyent. Natural gas was evaluated at 748ml/gh (620ml/gh for C1 and 120 ml/gh for C2). The reaction products were analyzed using a 2 m Porapak Q column. Conversion and product distribution were expressed on a carbon-atom basis. H-ZSM-11 and Zn-ZSM-11 catalyst (Si/AI=17) with Zn molar fraction = 0.86, was synthesized and characterized in our laboratory [8,9]. 3.RESULTS AND DISCUSSION 3.1 Natural Gas Studies The results of NG conversion and products distribution at 550~ and total pressure of latin, over Zn-ZSM-11 zeolite are summarized in table 1. As we can see C1 was not converted in the reaction conditions analyzed, meanwhile C2 was transformed on 40%.
Table 1" Natural Gas conversion and products distribution using Zn-ZSM-11 catalyst at 550~ and Total pressure, Tp = l atm Molar Fraction in the feed GHSV Conversion Productsdistribution ml/gh mol % (C) mol % (C) C1 C2 C3 C4 C2-AH
0.828 0.161 0.008 0.003
620 120 5.96 2.23
0 46.53 78.78 100
78.09 14.54 0.43 0 2.77 4.17
3.2 Methane and Ethane studies Table 2 gives catalytic data and results conversion and the reaction products distribution using two different feeds: a)Cl and b) C2/C2+N2 a t 550 ~ over Zn-ZSM-11 as a function of space velocity and the molar fraction of C2/C2+N2. C2 conversion and aromatics yield increase as the molar fraction of C2 in the feed increases and decreasing the space velocity [10]. Methane was not converted under the same reaction conditions and not even at lower space velocity (590ml/g.h.) 3.3 Methane + Ethane additive studies In table 3 we can be seen the results obtained using C1+C2 as feed over H-ZSM11 and Zn-ZSM 11 zeolites at different molar fraction of C2 and space velocities. Zn-ZSM11 zeolite appeared as a good material for CI activation with C2 at C2/C2+C1- 0.6 and 2240 ml/g.h. The aromatics yield reaches a maximum about 40% at 810mol/g.h. H-ZSMll zeolite
237
activates methane only about 2% at the better reaction condition. Taking into account above results we choice Z n - Z S M l l zeolite to study the effect of reaction condition over C1 transformation and product distributions. T a b l e 2 : C 1 and C2 conversion and products distribution at different space velocity and molar fraction of C2 (C2/C2+N2) GHSV (ml/gh) C1 Conversion(*) C2 Molar fraction(**)
2240
810
0
0
0.36
1
0.36
1
C2 (Conversion)
6.5
12
10.75
18
C2= (Mol% C)
4.8
5.8
5.5
6.2
AH(MoI% C)
1.25
3.5
4
7.75
Other (Mol% C)
0.45
2.7
1.25
4.05
(*) Feed: C1, Tp =latm; (**) Feed: C2/C2+N2, Tp=latm
T a b l e 3 : H - Z S M - 1 1 and Zn-ZSM-11 catalytic activity using C l + C 2 as feed. GHSV (ml/hg)
2240
810
Catalyst C2/C1+C2 in the feed (*)
Zn-ZSM- 11 0.6 0.26
H-ZSM- 11 0.63 0.27
Zn-ZSM- 11 0.6 0.26
H-ZSM- 11 0.63 0.27
C2 Conversion, mol % C
35.47
24.16
1.91
1.18
52.25
37.05
2.06
1.25
C 1 Conversion, mol % C
21.85
5.02
1.99
0
39.55
10.9
3.34
0.08
Products distribution mol% (C) CI
18.84
56.16
22.41
57.83
15.95
5 1 . 5 7 2 1 . 5 7 57.63
C2
48.92
30.98
75.66
41.82
35.15
26.52
7 6 . 0 8 41.79
C2-
5.63
10.77
1.93
0.36
3.95
5.83
2.35
AH
22.51
1.52
0
0
38.88
15.7
0
0
Others
4.08
0.57
0
0
6.06
0.39
0
0
0.58
(*)Temperature: 550~ Total pressure 1 atm. C1 and C2 conversion increased as the molar fraction of C1 diminished. C2 was converted more efficiently in presence of C1 than in presence of N2 at the same molar fraction (Table 2). Furthermore, C1 was activated raising to excellent conversion levels (40%), at molar fraction 0.4 and G H S V - 810ml/g.h. We suggest that C1 could be activated
238 by C2, initiating in this way its transformation [3]. The progress of the catalytic reactions of a gas mixture (C1+C2) at 550~ can be observed in Fig. 1 and 2. These figures show C1 and C2 conversion at different molar fraction of C1 and GHSV=2240 and 810. According to the data showed in figure 1 and 2, C1 conversion decreases as its molar fraction in the feed increases, reaching a value of C 1 conversion = 0 at x(C 1)>0.82. Upon this molar fraction C 1 was not converted. This has been supported by the data showed in table 1, where the molar fraction of C1 in NG was 0.828 and C1 was not activated even at lower GHSV than the space velocity used for plots 1 and 2. In Figure 3 and 4 show propane (C3), ethylene (C2=), butane (C4) and aromatic hydrocarbons (AH) yields at different GHSV and as a function of C1 molar fraction. C3 and AH yields were increased by decreasing molar fraction of C 1.
60
40
GHSV(C2)=810 mYgh
GHSV(C2)=2240 ml/gh O
50
o 30
o
|
|
i
conv. c2 ~ o
ae 40
0
0
Conv. C1
|
| 2o 1o 10 0 0.40
0.50
0.60
0.70
0.80
v
0.90
0.40
0.50
Fracci6n Molar de Cl
0.60
0.70
0.80
0.90
Fracci6n Molar de C1
Figures 1-2: C I and C2 conversion against the molar fraction of C 1 in the feed, at Tp- 1 atm and 550~ over Zn-ZSM-11 zeolite.
A 45
M 25
o
2)"2240 ml/gh
o
GHSV(C2)=810 ml/gh
40
"j 2o
| 3s
8_
a_ 2o
HA
2s 9 'U
10
0
9u 15
C2=
lO
| a
.....
0
0.40
0.50
0.60
0.70
0.80
FracciOn Molar de C1
0.90
'E
5
D
0
.
.
, O .
0.40
.
.
.
.
0.50
,
.
0.60
0.70
0 . 8 0 0.90
Fracci6n Molar C1
Figures 3-4: Products distribution from C1 and C2 interaction against the molar fraction of C 1 in the feed, at Tp- 1 atm and 550~ over Zn-ZSM-11 zeolite.
239 Thus, methane activation could occur through the interaction with ethane (or C2+ carbenium ions) toward aromatization steps. Aromatic hydrocarbons are the main products obtained at C1/CI+C2 = 0.4
45 ~"
=
GHSV(C2)"810 ml/gh
25
ae 40
GHSV(C2)-S~0
=25
o. 2 0
II
c2=- /
IO .o
N 5 a
0
0
5 10 15 20 25 30 35 40 45 Conversi6n de Cl, reel % (C)
..
-
0
,,
.-.
5 10 15 20 25 30 35 40 45 50 55 ConversiOn de C2, tool % (C)
Figures 5-6: Products distribution from C1 and C2 interaction against the conversion levels of C 1 and C2 at Tp = 1 atm and 550~ over Zn-ZSM-11 zeolite. Figures 7-9 show the effect of time on stream over C 1 and C2 conversion and product 45 4O o
7
|3o
6 4
2O
o C3
2
lO
1
5 o
800
k----~-~m
9 A
9 9
_.~
A
AA AA
0
I
1.oo
TOS, rain.
0
60o
1 2 0 0 1 8 0 0 2 4 0 0 300o 1"08, mln.
Figures 7-8: Change in C I and C2 conversion and gaseous products distribution as a function of TOS at Tp = l atm and 550~ over Zn-ZSM-11 zeolite.
240
40
30
_~ o E
~-
,
25
,,\
20
15
o ",, BTX~
5 1 TMB ~ 0
600
\.o
t, ~"~~
1200 1800 2400 3000 TOS, min
Figure 9: Aromatics distribution as a function of TOS at Tp = 1 atm and 550~ ZSM- 11 zeolite from C 1+C2 interaction.
over Zn-
distribution. C1 and C2 conversion decrease quickly as well as aromatics yield with TOS, whereas C2 = and C4 increase slowly. C3 yield decrease very slowly. These results are in accordance with the fact that C3 is the probable primary product of C I activation with C2, C2 = is a primary product of C2 dehydrogenation, C4 would be the first oligommer from C2 = and others are secondary. 4.CONCLUSIONS Catalytic transformation of C2 is improved by increasing its molar fraction in the feed, using N2 as diluyent. Methane was not converted under the same reaction conditions. The ethane is able to activate methane at low molar fraction of C 1 in the feed. C 1 conversion was very high, (40 %) at 550~ GHSV(C2)=810ml/gh and total pressure 1 atm, over ZnZSM-11. The formation of aromatic-rich hydrocarbons has been allowed at molar fraction of C1 C1/CI+C2 = 0.4
REFERENCES 1. D.E.Walsh, S.Han, R.E. Palermo, J.Chem.Soc.Chem.Commun. 18(1991 ) 1259. 2. S.Han, RE.Palermo, J.A.Pearson, D.E.Walsh, Catal. Lett., 16(1992)263-268 3. S.Han, D.J.Martenak, R.E.Palermo, J.A.Pearson, D.E.Walsh, J.Catal. 136(1992)578. 4. K.Wada, Y.Watanabe, F.Saitoh, T.Suzuki, Appl.Catal., 88(1992)23-28 5. L. Wang, L. Tao, M. Xie, G. Xu, Catal. Lett. 21 (1993)35. 6. L.B. Pierella, L. Wang, O.A. Anunziata, React.Kinet.Catal.Lett., 60 (1997) 101. 7. F. Solymosi and A. Szoke, Appl.Catal., 166(1)(1998)225-235. 8. O.A. Anunziata, L.B .Pierella, Catal. Lett. 19 (1993) 143. 9. O.A. Anunziata, L.B. Pierella, R.G. Marino, Appl.Catal., 165(1997)35-49 10. L.B. Pierella, G.A. Eimer, O.A. Anunziata, React.Kinet.Catal.Lett.,63(1998)271-278. 11. J. Abbot, A. Corma, B. Woiciechowski, J. Catal. 92 (1985) 398. 12. T. Inui, J. Og The Japan Petrol. Inst.- Sekiyu Gakkaishi 33(4)(1990) 198.
M e t h a n e t r a n s f o r m a t i o n into aromatic h y d r o c a r b o n s ethane over Z n - Z S M - 1 1 zeolite
235
by activation with
Liliana B. Pierella(*), Griselda A. Eimer(+) and Oscar A. Anunziata(*) CITeQ (Centro de Investigaci6n y Tecnologia Quimica) Facultad C6rdoba, Universidad Tecnol6gica Nacional. CC 36 -SUC 16, (5016) C6rdoba, ARGENTINA. e-mail: [email protected] - an [email protected] FAX:054-51-690585 ABSTRACT Very high levels of methane (C1) conversion to aromatic hydrocarbons were obtained by interaction with ethane (C2) (molar fraction in the feed: C1/CI+C2 = 0.4-0.8) over Zn-ZSM11 (molar fraction Zn/Zn+H-0.86) at 550~ and total pressure of 1 atm. The yield in aromatic hydrocarbons was about 10-40 mol% C. I.INTRODUCTION Direct conversion of methane (C1) to more valuable compounds, such as liquid hydrocarbons is not only a promising approach for the utilization of natural gas (NG) resource but also a challenging technical project. C1 (the main compound of NG) conversion, under non-oxidizing conditions is a great task to catalysis science. Walsh et al. reported [1] the formation of aromatic-rich hydrocarbons from DPO of C 1 with 02 over ZSM5 in the presence of small amounts (0.2-0.4 mol%) of light hydrocarbons additive, such as propane (C3) or propylene (C3 =) in the feed. The reaction sequence involves DPO of C1 to methanol (C 1OH) followed by the C1OH-gasoline reaction and the hydrocarbons are comes from, alkenes or alkanes precursors present in the feed to initiate the MTG reaction. Han et al. [2,3] reported similar results showing product selectivity to COx >80% and to liquid hydrocarbons products >13%. Wada [4] reported that unpromoted rare earth oxides were active for the oxidative methylation of C2 with C 1, indicating that E u 2 0 3 - O x catalyst gave the maximum yield of C3 products under selected reaction conditions. Thus the maximum C3 compound was 8%. Recently Wang [5] and Pierella [6] reported the aromatization of C1 in the presence of small amount of light hydrocarbons under non-oxidizing conditions over Mo-Zeolite at low pressure (1-2atm). Commercial NG can contain up to 10 % of ethane (C2). Solymosi and Szoke [7] reported high ethane conversion and benzene selectivity using MoC/ZSM-5 at 700~ In this work, the activation of methane with ethane and the transformation of pure methane and pure ethane, using HZSM-11 and Zn loaded ZSM-11 zeolite, have been studied. The final objective is the transformation of NG into petroleum-chemicals products.
2.EXPERIMENTAL Catalytic reactions were carried out in a continuous flow quartz reactor with an inner diameter of 10 mm at atmospheric pressure. Products were withdrawn periodically from the (*) CONICET-Researcher; (+) CONICET Fellowship. Research Grants: PID-CONICET N~ 6963/96 and CONICOR NO3663/96.
236
outlet of the reactor and analyzed by on-line gas chromatography equipped with a FID detector. The following feeds were used in this study: high purity methane (>99.97%) ethane (>99.997%) supplied by AGA. Commercial Natural Gas (analysis: C1 = 82.8; C2 = 16.1; C3 = 0.8; C4 = 0.5 mol%) was supplied by ECO-GAS (Argentine). The studies with methane were carried out at GHSV = 2224, 820 and 590 ml/gh. For ethane GHSV = 2224 and 820ml/gh were employed and molar fraction x(C2) = 1 and x(C2) = 0.36 using N2 as diluyent. Natural gas was evaluated at 748ml/gh (620ml/gh for C1 and 120 ml/gh for C2). The reaction products were analyzed using a 2 m Porapak Q column. Conversion and product distribution were expressed on a carbon-atom basis. H-ZSM-11 and Zn-ZSM-11 catalyst (Si/AI=17) with Zn molar fraction = 0.86, was synthesized and characterized in our laboratory [8,9]. 3.RESULTS AND DISCUSSION 3.1 Natural Gas Studies The results of NG conversion and products distribution at 550~ and total pressure of latin, over Zn-ZSM-11 zeolite are summarized in table 1. As we can see C1 was not converted in the reaction conditions analyzed, meanwhile C2 was transformed on 40%.
Table 1" Natural Gas conversion and products distribution using Zn-ZSM-11 catalyst at 550~ and Total pressure, Tp = l atm Molar Fraction in the feed GHSV Conversion Productsdistribution ml/gh mol % (C) mol % (C) C1 C2 C3 C4 C2-AH
0.828 0.161 0.008 0.003
620 120 5.96 2.23
0 46.53 78.78 100
78.09 14.54 0.43 0 2.77 4.17
3.2 Methane and Ethane studies Table 2 gives catalytic data and results conversion and the reaction products distribution using two different feeds: a)Cl and b) C2/C2+N2 a t 550 ~ over Zn-ZSM-11 as a function of space velocity and the molar fraction of C2/C2+N2. C2 conversion and aromatics yield increase as the molar fraction of C2 in the feed increases and decreasing the space velocity [10]. Methane was not converted under the same reaction conditions and not even at lower space velocity (590ml/g.h.) 3.3 Methane + Ethane additive studies In table 3 we can be seen the results obtained using C1+C2 as feed over H-ZSM11 and Zn-ZSM 11 zeolites at different molar fraction of C2 and space velocities. Zn-ZSM11 zeolite appeared as a good material for CI activation with C2 at C2/C2+C1- 0.6 and 2240 ml/g.h. The aromatics yield reaches a maximum about 40% at 810mol/g.h. H-ZSMll zeolite
237
activates methane only about 2% at the better reaction condition. Taking into account above results we choice Z n - Z S M l l zeolite to study the effect of reaction condition over C1 transformation and product distributions. T a b l e 2 : C 1 and C2 conversion and products distribution at different space velocity and molar fraction of C2 (C2/C2+N2) GHSV (ml/gh) C1 Conversion(*) C2 Molar fraction(**)
2240
810
0
0
0.36
1
0.36
1
C2 (Conversion)
6.5
12
10.75
18
C2= (Mol% C)
4.8
5.8
5.5
6.2
AH(MoI% C)
1.25
3.5
4
7.75
Other (Mol% C)
0.45
2.7
1.25
4.05
(*) Feed: C1, Tp =latm; (**) Feed: C2/C2+N2, Tp=latm
T a b l e 3 : H - Z S M - 1 1 and Zn-ZSM-11 catalytic activity using C l + C 2 as feed. GHSV (ml/hg)
2240
810
Catalyst C2/C1+C2 in the feed (*)
Zn-ZSM- 11 0.6 0.26
H-ZSM- 11 0.63 0.27
Zn-ZSM- 11 0.6 0.26
H-ZSM- 11 0.63 0.27
C2 Conversion, mol % C
35.47
24.16
1.91
1.18
52.25
37.05
2.06
1.25
C 1 Conversion, mol % C
21.85
5.02
1.99
0
39.55
10.9
3.34
0.08
Products distribution mol% (C) CI
18.84
56.16
22.41
57.83
15.95
5 1 . 5 7 2 1 . 5 7 57.63
C2
48.92
30.98
75.66
41.82
35.15
26.52
7 6 . 0 8 41.79
C2-
5.63
10.77
1.93
0.36
3.95
5.83
2.35
AH
22.51
1.52
0
0
38.88
15.7
0
0
Others
4.08
0.57
0
0
6.06
0.39
0
0
0.58
(*)Temperature: 550~ Total pressure 1 atm. C1 and C2 conversion increased as the molar fraction of C1 diminished. C2 was converted more efficiently in presence of C1 than in presence of N2 at the same molar fraction (Table 2). Furthermore, C1 was activated raising to excellent conversion levels (40%), at molar fraction 0.4 and G H S V - 810ml/g.h. We suggest that C1 could be activated
238 by C2, initiating in this way its transformation [3]. The progress of the catalytic reactions of a gas mixture (C1+C2) at 550~ can be observed in Fig. 1 and 2. These figures show C1 and C2 conversion at different molar fraction of C1 and GHSV=2240 and 810. According to the data showed in figure 1 and 2, C1 conversion decreases as its molar fraction in the feed increases, reaching a value of C 1 conversion = 0 at x(C 1)>0.82. Upon this molar fraction C 1 was not converted. This has been supported by the data showed in table 1, where the molar fraction of C1 in NG was 0.828 and C1 was not activated even at lower GHSV than the space velocity used for plots 1 and 2. In Figure 3 and 4 show propane (C3), ethylene (C2=), butane (C4) and aromatic hydrocarbons (AH) yields at different GHSV and as a function of C1 molar fraction. C3 and AH yields were increased by decreasing molar fraction of C 1.
60
40
GHSV(C2)=810 mYgh
GHSV(C2)=2240 ml/gh O
50
o 30
o
|
|
i
conv. c2 ~ o
ae 40
0
0
Conv. C1
|
| 2o 1o 10 0 0.40
0.50
0.60
0.70
0.80
v
0.90
0.40
0.50
Fracci6n Molar de Cl
0.60
0.70
0.80
0.90
Fracci6n Molar de C1
Figures 1-2: C I and C2 conversion against the molar fraction of C 1 in the feed, at Tp- 1 atm and 550~ over Zn-ZSM-11 zeolite.
A 45
M 25
o
2)"2240 ml/gh
o
GHSV(C2)=810 ml/gh
40
"j 2o
| 3s
8_
a_ 2o
HA
2s 9 'U
10
0
9u 15
C2=
lO
| a
.....
0
0.40
0.50
0.60
0.70
0.80
FracciOn Molar de C1
0.90
'E
5
D
0
.
.
, O .
0.40
.
.
.
.
0.50
,
.
0.60
0.70
0 . 8 0 0.90
Fracci6n Molar C1
Figures 3-4: Products distribution from C1 and C2 interaction against the molar fraction of C 1 in the feed, at Tp- 1 atm and 550~ over Zn-ZSM-11 zeolite.
239 Thus, methane activation could occur through the interaction with ethane (or C2+ carbenium ions) toward aromatization steps. Aromatic hydrocarbons are the main products obtained at C1/CI+C2 = 0.4
45 ~"
=
GHSV(C2)"810 ml/gh
25
ae 40
GHSV(C2)-S~0
=25
o. 2 0
II
c2=- /
IO .o
N 5 a
0
0
5 10 15 20 25 30 35 40 45 Conversi6n de Cl, reel % (C)
..
-
0
,,
.-.
5 10 15 20 25 30 35 40 45 50 55 ConversiOn de C2, tool % (C)
Figures 5-6: Products distribution from C1 and C2 interaction against the conversion levels of C 1 and C2 at Tp = 1 atm and 550~ over Zn-ZSM-11 zeolite. Figures 7-9 show the effect of time on stream over C 1 and C2 conversion and product 45 4O o
7
|3o
6 4
2O
o C3
2
lO
1
5 o
800
k----~-~m
9 A
9 9
_.~
A
AA AA
0
I
1.oo
TOS, rain.
0
60o
1 2 0 0 1 8 0 0 2 4 0 0 300o 1"08, mln.
Figures 7-8: Change in C I and C2 conversion and gaseous products distribution as a function of TOS at Tp = l atm and 550~ over Zn-ZSM-11 zeolite.
240
40
30
_~ o E
~-
,
25
,,\
20
15
o ",, BTX~
5 1 TMB ~ 0
600
\.o
t, ~"~~
1200 1800 2400 3000 TOS, min
Figure 9: Aromatics distribution as a function of TOS at Tp = 1 atm and 550~ ZSM- 11 zeolite from C 1+C2 interaction.
over Zn-
distribution. C1 and C2 conversion decrease quickly as well as aromatics yield with TOS, whereas C2 = and C4 increase slowly. C3 yield decrease very slowly. These results are in accordance with the fact that C3 is the probable primary product of C I activation with C2, C2 = is a primary product of C2 dehydrogenation, C4 would be the first oligommer from C2 = and others are secondary. 4.CONCLUSIONS Catalytic transformation of C2 is improved by increasing its molar fraction in the feed, using N2 as diluyent. Methane was not converted under the same reaction conditions. The ethane is able to activate methane at low molar fraction of C 1 in the feed. C 1 conversion was very high, (40 %) at 550~ GHSV(C2)=810ml/gh and total pressure 1 atm, over ZnZSM-11. The formation of aromatic-rich hydrocarbons has been allowed at molar fraction of C1 C1/CI+C2 = 0.4
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