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Cracking light gas oil on catalysts containing zeolite
32
L . V . KOVAL'CHUK et al.
t h e concentration and strength of acidic centres (H 0 according to Hammett) of the carrier surface and with the concentration of the adsorbed complex. 2. It was shown t h a t on keeping the complex, catalytic activity m a y both increase and decrease, which may be due to interaction with acid centres of various strengths. Activation is observed during interaction with weak acidic centres: 6.8 ~>H0 >13.3. Stronger acidic centres (e.g. AlcOa) form strong bonds with the adsorbed complex, which results in the deactivation of the catalyst. REFERENCES
1. Yu. M. ZHOROV, A. V. SHELKOV and G. M. PANCHENKOV, K i n e t i k a i kataliz 15, 1091, 1974 2. Yu. M. ZHOROV et al., Neftckhimiya 15, 486, 1975 3. E. HERMANA, A. GAMERO, E. TIJERO and J. BLANKO, An. Quimica 67, 1051 1971 4. P. R. RONY and J. F. FROTH, J. Molec. Catal. 1, 13, 1975 5. K. TANABE, Tverdyye kisloty i osnovmliya (Solid Acids and Bases). Mir, Moscow, 1973 6. H. A, BENESI, J. Phys. Chem. 61, 970, 1957 7. T. N I S H I Z A W A et al., 4-th Intern. Congr. Catalysis, Moscow, Pr. No. 55, 1968 8. S. 1KALI~qOWSKI, S. SZOZEPANSKA, A. BIELANSKI and J. SLOCZYNSKI, $. Catalysis 4, 324, 1965 9. J. UYTTERHOVEN, M. SLEEX and J. FRIPIAT, Bull. chim. France, No. 6, 1800, 1965 10. R. P. EISHENS and V. A. PLISKIN, Kataliz. Issledovaniyc poverkhnosti katalizatorov (Catalysis. Study of Catalyst Surface). Izd. inostr, lit., Moscow, 1960 11. J. T. VANGERMET and P. R. WILKINSON, J. Phys. Chem. 68, 645, 1964
CRACKING LIGHT GAS OIL ON CATA ZEOLITE *
I~S CONTAINING
L . V. KOVAL'CHUK, G. ~/I. TAKItTAROVA a n d I~. V. TOPCHIYEVA M. V. Lomonosov State University, Moscow (Received 22 J u l y 1975)
A COMPARATIVE study was made of the activity of cation-decationated forms of catalysts containing zeolite in cracking a kerosine-gas oil fraction. Calcium-decationated and lanthanum-decationated samples were obt a i n e d by treatment of the sodium form of a catalyst containing zeolite with a mixture of solutions of ammonium salts and a polyvalent cation [1]. Catalyst compositions are shown in Table 1. * Ncftekhimiya 17, No. 2, 257-261, 1977.
Cracking light gas oil on catalysts containing zeolite
33
All samples were heat-treated (calcination in air at 550 ° for 6 hr) a n d subjected to heat t r e a t m e n t in the presence of steam (calcination in the flow of 100% steam at 650 ° for 6 hr). Experiments were carried out in a conTABLE ]. CO~POSITIONOV CATALYSTSCONTAIniNGZEOLITE No. of samplo
Cationic
MexOy I Na20
form
~o w t .
Ca
1'2 2.0 3.1 2"7 4.1 6.7
La
Na
I
NH~
I
Me
Me/NH~
% 1.2 0.9 0.9 1.3 1.3 1.2
57"6 47"7 26"7 52"8 38"1 20"2
19"9 15"6 15"3 21'6 22"2 21"3
0-4 0.8 2.2 0-5 1.0 2.9
22.5 36.7 58"0 25.6 39-7 58"5
tinuous apparatus in the temperature range of 400-450 ° and at a space velocity of i hr -x. Catalyst a c t i v i t y was determined from the yield of of final boiling point 200 ° during cracking a kerosine-gas oil fraction of Malgobek oil. Gaseous cracked products were analysed in a P y e Unicam chromatograph w i t h a flame-ionization detector. Products were separated with linear p r o g r a m m i n g in the interval of 90-150 ° at a rate of heating of 1 deg/min. The effect o f t e m p e r a t u r e on gasoline a n d gas yield was examined using three calciumdecationated a n d one l a n t h a n u m - d e c a t i o n a t e d catalyst containing zeolite. Results of cracking are shown in Tables 2 a n d 3. As w i t h all catalytic processes, t e m p e r a t u r e is the main, highly effective parameter, which influences the degree of catalytic cracking a n d p r o d u c t yields. TABLE 2. RELATION BETWEEN THE YIELD OF CRACKED PRODUCTS ON CATALYSTS CONTAINING ZEOLITE AND TEMPERATURE ( % Wt.)
Gasolino No. of catalyst
Cation Ca La
400 °
450 °
425 °
I
II
I
II
f
57 54 51 52
68 58 55 60
54 50 49 50
65 57 53 54
48 47 46 47
400 ° I T I- - II 56 51 50 52
5 5 5 7
3 4 3 6
Gas 425 ° 8 9 7 8
4 8 4 6
450 °
I
II
17 11 11 14
7 11 6 7
Note. In Tables 2,4 and 5: I-catalyst subjected to heat treatment; II--catalyst subjected to heat and steam treatment.
T e m p e r a t u r e has an extremal effect on the catalytic activity of catalysts containing zeolite; m a x i m u m activity is n o r m a l l y in the t e m p e r a t u r e range of 450-500 ° [2-4]. The catalysts e x a m i n e d are highly active a n d selective a n d therefore, m a x i m u m gasoline yield is displaced to lower temperatures, w i t h t h e highest gasoline yield a t a t e m p e r a t u r e of 400 ° (Table 2).
34
L . V . KOVAL'CHUK et al.
An increase in temperature from 400 to 450 ° reduces gasoline yield and increases the contents of gaseous products up to C4, inclusive. The effect of temperature varies for catalysts with different degrees of substitution on TABLE 3.
C O N T E N T S OF C l - C 4 H Y D R O C A R B O N S I1~ CRACKED GAS OIL PRODUCTS
(mol. ~/o)
U S I N G H E A T - T R E A T E D CATALYSTS CONTAII~*II~'G Z E O L I T E
No. of catalyst
Ca
Cation
T,°C
C1
--par: ~ ole-
I ffln
Ca
La
fin
Ca
Z paraffins/ / Z olefins
para-gin ole-fin Pill:a" °~l~"
400 4.9 4251 12.7 450 21.2
3.9 6.5 8.2
7.5 6.9 3.2
24.0 23.5 23.7
10"0 36"0 10"2 30"9 9"2 25-0
L3'7 9'3 9'5
2.2 2.8 3.6
400] 425 450
2.6 4.3 5.7
2.4 3.9 3.2
5.1 22-6 6"9 27-4 6.2 21.6
3"1 50'7 37'6 37'7
13.5 11.1 15.5
2.7 2.1
400 7.5 425 I 6.9 45O 12.3
3.8 4.3 7.8
5.8 6.9 8.5
12.5 21.4 18.0
12'3 47.1 I 11"0 i i 12"0 40.8 I 7.7 14'0 31.9 7.5 !
400 I
4-5 8-3 8.41
7.0 5.3 2.7
34.0 28-5 24-9
9"2 32 4 7'7' 7'5 2611 I 6.9 5'5 28.2 9.6!
5.2 17.4 t4501 20.7
3.6
2.4 2.7 2.3
d
4.13"2 4.6
calcium, or lanthanum and with a different ratio of cationic and decationa~ed sections. On increasing temperature from 400 to 450 ° gasoline yield decreases for calcium catalysts, %: No. 1 by 9, No. 2 by 7, No. 3 by 5 and lanthanum sample No. 3 by 5~/o. At the same time gas yield increases by 12, 6, 6 and 7 ° , respectively. Increasing temperature from 400 to 450 ° has a most marked effect on the behaviour of the calcium catalyst sample No. 1 and results in a very sudden change in gasoline and gas yields due apparently, to the high degree of decationation of this sample. An increase in the degree of substitution by calcium and a reduction in the degree of decationation increases catalyst stability, the effect of temperature on samples Nos. 2 and 3 is therefore less marked. No special differences are evidently observed between calcium and lanthanum samples in gasoline and gas yields on changing the temperature of cracking. The temperature of cracking has the same effect on the activity of steamtreated samples as on heat-treated catalysts. The distribution of gaseous cracked products varies according to conditions of cracking and the degree of exchange by a polyvalent cation. With an increase of the temperature of cracking to 450 ° the content of CI fraction in gaseous cracked products increases on all catalysts. The lower the degree of
35
C r a c k i n g l i g h t g a s oil o n c a t a l y s t s c o n t a i n i n g zeolite
exchange by calcium, the more considerable this increase. For a degree of exchange of 22.5% by calcium the amount of C1 fraction increases approximately four-fold, for a lanthanum sample the content of this fraction also increases four times. TABLE 4. R E I ~ T I O X V B E T W E E N CRACKED P R O D U C T Y I E L D AND T H E CONTENTS OF P O L Y V A L E N T CATIONS ( W t . ~/0)
No. of sample
1 2
Cationic form
] ! I
3
i I
1
t
2 3
Cation Gasoline c o n t e n t , ~o
Gas
Coke
I Ill
III
I
Conversion
Selectivity
I III
I tli
Ca
22'5 36'7 58"0
57 54 51
68 58 55
5 5 5
3 4 3
4 4 4
3 3 3
66 63 60
74 65 61
86 86 85
92 89 90
25"6 39"7 58"5
54 53 52
71 63 60
8 i
4
La
8 7 7
4 4 5
70 67 66
79 72 71
77 79 79
90 88 85
7i5 7
6
On increasing temperature the content of fraction C2 increases in proportion to the degree of substitution by calcium. The overall amount of C2 fraction remains unchanged with an increase of temperature on lanthanum catalyst No. 3, the same way as on calcium catalyst No. 1; the overall amount of C2 fraction remains unchanged with an increase of temperature, however, ethane content is about doubled in ethane-ethylene fractions. An increase in temperature has little effect on the yield of fraction Ca T A B L E 5. C O N T E N T S C 1 - C 4 H Y D R O C A R B O N S I N GASEOUS PRODUCTS OF CRACKED GAS O I L
~TO, o f
samplo
Cationic form
ZCa
i+
~f
EC+
o
°~
1 (I) 1 (II)
2 2 3 3
(I) (II) (I) (II)
1 I 2 2 3 3
(I) (II) (I) (II) (I) (II)
Ca
La
11"4 11"6 7"5 9"5 9-6 9-9
34"0 35"8 25'7 37"4 24"8 35-6
49.7 48.5 64-2 48.0 58.1 50.3
30.4 29.6 44.1 30.3 42.5 31.1
13.7 14-1 13.5 12.7 11"0 14-1
0.5 0-4 0.5 0.7 0"6 0.5
2.4 1.4 7.3 2.7 1.0 1.5
2.2 1.7 3-6 2.5 2.4 1.9
16"4 4-2 11-5 6"8 11"5 8"4
39.4 31"6 40"5 32.6 43"2 41"7
33.7 62.9 42.4 58.3 40.1 47-6
25.7 44.1 30.3 37.8 28.2 33.4
4.7 11.1 7.7 13.5 7.7 9-0
0'6 0.8 0.6 0-3 0"6 0"5
5.0 1.9 3.6 3.3 3.7 3.3
3.7 5-6 3.2 2.8 3.2 3.1
36
L. V. KOVAL'CHUK ~t al.
and on the ratio of paraffin and olefin hydrocarbons during cracking on calcium catalysts containing zeolite. On increasing the temperature of cracking on a lanthanum sample, the overall content of fraction Ca decreases, however, the amount of propane in a propane-propylene fraction somewhat increases. The content of fraction C4 decreases noticeably on increasing the temperature of cracking on catalyst samples containing calcium (No. 1--by 15.2~/o, No. 3 - - b y 18.7%). When cracking is carried out on a lanthanum catalyst temperature has little effect on the content of fraction C4. The amount of paraffin hydrocarbons in a butane-butylene fraction decreases on all catalysts on increasing temperature. The ~ paraffins ratio is higher for a catalyst olefins containing lanthanum. Highest gasoline yield on the samples studied in the temperature range of 400-450 ° is therefore obtained at the temperature of 400 ° . The effect of temperature is directly related to the type of polyvalent cation, the degree of exchange and the ratio of cation and decationated sections. The chemical structure of a polyvalent cation has the most noticeable effect on the catalytic activity, selectivity and stability of zeolites. It was therefore interesting to observe this effect in cracking light gas oil at a temperature of 400 ° as the optimum for a series of calcium and lanthanum catalysts (Table 1). Table 4 shows results of cracking light gas oil on catalysts containing zeolite. The Table illustrates that an increase in the contents of polyvalent cations has' little influence over the activity of heat-treated catalysts containing zeolite. As a result of heat and steam treatment the overall conversion, gasoline yield and selectivity increase. Gas and coke contents decrease. This is particularly marked for samples with a high ratio of decationated and cation segments. Gasoline yield on calcium and lanthanum samples (No. 1) increases by 11 and 17%, respectively. It should be noted that an increase in the contents of cation segments results in an increased stabilization of catalysts containing zeolite and for these the tendency of increasing activity after heat and steam treatment is less marked (samples iNos. 1 and 3). Increasing the degree of substitution by a polyvalent cation reduces the activity of heat and steam-treated samples. Overall conversion and gasoline yield decrease. Thus, on increasing the degree of exchange by a polyvalent cation from about 22 to 60%, gasoline yield on calcium and lanthanum catalysts is reduced by 13 and 11~/o, respectively. Cation-decationated forms of catalysts containing zeolite with a given ratio of cationic and decationated segments are therefore highly active and selective. Calcium samples with a conversion lower t h a n t h a t of lanthanum samples are highly selective with respect to gasoline yield and produce less gas both before and after heat-steam treatment. Table 5 shows gas analysis during light gas oil cracking.
Cracking light gas oil on Catalysts containing zeolite
37
Isobutane is the main hydrocarbon in the cracked gas, its content increases with an increase of the degree of substitution by calcium and janthanum. With an increase of the degree of substitution the yield of C2 fraction decreases somewhat and the overall content of C4 fraction increases. It should be nofed that on calcium samples the amount of isobutane is higher on average than on lanthanum. However, the pattern changes after the treatment of samples with steam. The amount of isobutane decreases on catalysts containing calcium; the higher the degree of exchange by calcium, the more noticeable the reduction. Isobutane yield increases on catalysts containing lanthanum and with a reduction of the degree of exchange by lanthanum, isobutane content increases. After heat and steam treatment the effect of C2 and C3 fractions increases with an increase of the degree of substitution by calcium cations. In contrast to calcium, on lanthanum samples after heat and steam treatment, the overall contents of C2 and C3 fractions decreases in inverse proportion to the degree of exchange by lanthanum. It may be assumed that gasolines obtained using catalysts containing lanthanum, will be characterized by a large number of iso-compounds even in the liquid phase. An analysis of the composition of cracked gas shows that after heat and steam treatment the contents of saturated hydrocarbons somewhat decrease. Increasing gasoline yield and overall conversion on catalysts containing zeolite after heat and steam treatment is, apparently due to various causes. Heat and steam treatment reduces the acidity of catalysts containing zeolite [5]. Gas and coke yields decrease at the same time. In addition, heat and steam treatment intensifies the migration of cations from the crystalline into the amorphous phase of the catalyst [6] and brings aluminium into the exchange state in zeolites with low cation density. It is also possible that as a result of heat and steam treatment zeolites break down into smaller, highly active 'crystals. The complex variation of the activity of catalysts containing zeolite, which takes place by the action of heat- and heat and steam treatments is due to a whole number of causes and one cannot point out any one of them as the main cause. SUMMARY
1. Highest gasoline yield in cracking a kerosine-gas oil fraction on catalyst samples containing zeolite is achieved at a temperature of 400 °. Increasing temperature results in more intensive cracking and changes the redistributing properties of catalysts. 2. Increasing the contents of polyvalent cations has little effect on the activity of heat-treated catalysts containing zeolite, but reduces the activity of heat and steam-treated samples.
38
V . A . ZAZHIGALOVet ~ .
REFERENCES 1. L. V. KOVAL'CHUK, G. N. T.4KHTAROVA and K. V. KOPCHIYEV, Vestn. MGU, ser. khim., No. 2, 162, 1975 2. Z. S. AGAMIRZOYEVA, Karl4. dis., Baku, 1973 3. O. A. MAM~YEV and A. Z. DOROGOCHINSKII, K h i m i y a i tekhnol, topliv i masel, No. 2, 7, 1972 4. V. M. KURGANOV, A. V. AGAFONOV, M. F. SININ, G. M. GITNIK, B. G. SOLOV'YEV, B. E. KUSHNER, B. M. GAL'PERIN, A. Z. STRIZHKOV, Z. G. BELYAYEVA, V. S. KNYAZEV, V. V. MOROZOV and M. S. GUSEV, Neftepererabotka i neftekhimiya, No. 4, 3, 1973 5. L. M. VISHNEVSKAYA, Kand. dis., MGU, Moscow, 1974 6. K. V. T O P C ~ V A , A. K. GAPEYEV, T. M. IVANOV, L. N. BURENKOVA, Ya. V. MIRSKII and S. N. KHADZHIYEV, Dokl. A N SSSR 215, 384, 1974
OXIDATION OF n-BUTANE ON VANADIUM-MOLYBDENUM OXIDE CATALYSTS * V. A. ZAZHIGALOV,G. A. KOMASHKO, A. I. PYATNITSKAYAand YA. B. GOROKHOVATSK~ (dec.) L. V. Pisarzhevskii I n s t i t u t e of Physical Chemistry, Ukr.S.S.R. Academy of Sciences
(Received 22 July 1976) PARTIAL oxidation of butane to obtain maleic anhydride (MA) has recently attracted the attention of scientists. In this study a vanadium-molybdenum oxide systeni (V-Me-O) with a different ratio of components was used as catalyst in this process. This catalytic system has previously been studied ¢[1-3] in selective oxidation of benzene and other hydrocarbons to maleic anhydride. EXPERIMENTAL
V-Mo-O catalyst samples were prepared by dissolving given ammonium paramolybdate and ammonium metavanadate samples. Solutions were evaporated and the residue dried at 110°, followed by heating in air at 600 ° for 6 hr. The catalyst was then compressed, crushed and a 0.5--1.0 m m fraction was then placed in a reactor. Specific surfaces of catalysts measured according to the thermal desorption of nitrogen (Table) were similar for all the samples studied before and after operation. X-ray spectra and E P R spectra of V-Mo-O catalysts were obtained after * Neftekhimiya 17, No. 2, 268-273, 1977.
L . V . KOVAL'CHUK et al.
t h e concentration and strength of acidic centres (H 0 according to Hammett) of the carrier surface and with the concentration of the adsorbed complex. 2. It was shown t h a t on keeping the complex, catalytic activity m a y both increase and decrease, which may be due to interaction with acid centres of various strengths. Activation is observed during interaction with weak acidic centres: 6.8 ~>H0 >13.3. Stronger acidic centres (e.g. AlcOa) form strong bonds with the adsorbed complex, which results in the deactivation of the catalyst. REFERENCES
1. Yu. M. ZHOROV, A. V. SHELKOV and G. M. PANCHENKOV, K i n e t i k a i kataliz 15, 1091, 1974 2. Yu. M. ZHOROV et al., Neftckhimiya 15, 486, 1975 3. E. HERMANA, A. GAMERO, E. TIJERO and J. BLANKO, An. Quimica 67, 1051 1971 4. P. R. RONY and J. F. FROTH, J. Molec. Catal. 1, 13, 1975 5. K. TANABE, Tverdyye kisloty i osnovmliya (Solid Acids and Bases). Mir, Moscow, 1973 6. H. A, BENESI, J. Phys. Chem. 61, 970, 1957 7. T. N I S H I Z A W A et al., 4-th Intern. Congr. Catalysis, Moscow, Pr. No. 55, 1968 8. S. 1KALI~qOWSKI, S. SZOZEPANSKA, A. BIELANSKI and J. SLOCZYNSKI, $. Catalysis 4, 324, 1965 9. J. UYTTERHOVEN, M. SLEEX and J. FRIPIAT, Bull. chim. France, No. 6, 1800, 1965 10. R. P. EISHENS and V. A. PLISKIN, Kataliz. Issledovaniyc poverkhnosti katalizatorov (Catalysis. Study of Catalyst Surface). Izd. inostr, lit., Moscow, 1960 11. J. T. VANGERMET and P. R. WILKINSON, J. Phys. Chem. 68, 645, 1964
CRACKING LIGHT GAS OIL ON CATA ZEOLITE *
I~S CONTAINING
L . V. KOVAL'CHUK, G. ~/I. TAKItTAROVA a n d I~. V. TOPCHIYEVA M. V. Lomonosov State University, Moscow (Received 22 J u l y 1975)
A COMPARATIVE study was made of the activity of cation-decationated forms of catalysts containing zeolite in cracking a kerosine-gas oil fraction. Calcium-decationated and lanthanum-decationated samples were obt a i n e d by treatment of the sodium form of a catalyst containing zeolite with a mixture of solutions of ammonium salts and a polyvalent cation [1]. Catalyst compositions are shown in Table 1. * Ncftekhimiya 17, No. 2, 257-261, 1977.
Cracking light gas oil on catalysts containing zeolite
33
All samples were heat-treated (calcination in air at 550 ° for 6 hr) a n d subjected to heat t r e a t m e n t in the presence of steam (calcination in the flow of 100% steam at 650 ° for 6 hr). Experiments were carried out in a conTABLE ]. CO~POSITIONOV CATALYSTSCONTAIniNGZEOLITE No. of samplo
Cationic
MexOy I Na20
form
~o w t .
Ca
1'2 2.0 3.1 2"7 4.1 6.7
La
Na
I
NH~
I
Me
Me/NH~
% 1.2 0.9 0.9 1.3 1.3 1.2
57"6 47"7 26"7 52"8 38"1 20"2
19"9 15"6 15"3 21'6 22"2 21"3
0-4 0.8 2.2 0-5 1.0 2.9
22.5 36.7 58"0 25.6 39-7 58"5
tinuous apparatus in the temperature range of 400-450 ° and at a space velocity of i hr -x. Catalyst a c t i v i t y was determined from the yield of of final boiling point 200 ° during cracking a kerosine-gas oil fraction of Malgobek oil. Gaseous cracked products were analysed in a P y e Unicam chromatograph w i t h a flame-ionization detector. Products were separated with linear p r o g r a m m i n g in the interval of 90-150 ° at a rate of heating of 1 deg/min. The effect o f t e m p e r a t u r e on gasoline a n d gas yield was examined using three calciumdecationated a n d one l a n t h a n u m - d e c a t i o n a t e d catalyst containing zeolite. Results of cracking are shown in Tables 2 a n d 3. As w i t h all catalytic processes, t e m p e r a t u r e is the main, highly effective parameter, which influences the degree of catalytic cracking a n d p r o d u c t yields. TABLE 2. RELATION BETWEEN THE YIELD OF CRACKED PRODUCTS ON CATALYSTS CONTAINING ZEOLITE AND TEMPERATURE ( % Wt.)
Gasolino No. of catalyst
Cation Ca La
400 °
450 °
425 °
I
II
I
II
f
57 54 51 52
68 58 55 60
54 50 49 50
65 57 53 54
48 47 46 47
400 ° I T I- - II 56 51 50 52
5 5 5 7
3 4 3 6
Gas 425 ° 8 9 7 8
4 8 4 6
450 °
I
II
17 11 11 14
7 11 6 7
Note. In Tables 2,4 and 5: I-catalyst subjected to heat treatment; II--catalyst subjected to heat and steam treatment.
T e m p e r a t u r e has an extremal effect on the catalytic activity of catalysts containing zeolite; m a x i m u m activity is n o r m a l l y in the t e m p e r a t u r e range of 450-500 ° [2-4]. The catalysts e x a m i n e d are highly active a n d selective a n d therefore, m a x i m u m gasoline yield is displaced to lower temperatures, w i t h t h e highest gasoline yield a t a t e m p e r a t u r e of 400 ° (Table 2).
34
L . V . KOVAL'CHUK et al.
An increase in temperature from 400 to 450 ° reduces gasoline yield and increases the contents of gaseous products up to C4, inclusive. The effect of temperature varies for catalysts with different degrees of substitution on TABLE 3.
C O N T E N T S OF C l - C 4 H Y D R O C A R B O N S I1~ CRACKED GAS OIL PRODUCTS
(mol. ~/o)
U S I N G H E A T - T R E A T E D CATALYSTS CONTAII~*II~'G Z E O L I T E
No. of catalyst
Ca
Cation
T,°C
C1
--par: ~ ole-
I ffln
Ca
La
fin
Ca
Z paraffins/ / Z olefins
para-gin ole-fin Pill:a" °~l~"
400 4.9 4251 12.7 450 21.2
3.9 6.5 8.2
7.5 6.9 3.2
24.0 23.5 23.7
10"0 36"0 10"2 30"9 9"2 25-0
L3'7 9'3 9'5
2.2 2.8 3.6
400] 425 450
2.6 4.3 5.7
2.4 3.9 3.2
5.1 22-6 6"9 27-4 6.2 21.6
3"1 50'7 37'6 37'7
13.5 11.1 15.5
2.7 2.1
400 7.5 425 I 6.9 45O 12.3
3.8 4.3 7.8
5.8 6.9 8.5
12.5 21.4 18.0
12'3 47.1 I 11"0 i i 12"0 40.8 I 7.7 14'0 31.9 7.5 !
400 I
4-5 8-3 8.41
7.0 5.3 2.7
34.0 28-5 24-9
9"2 32 4 7'7' 7'5 2611 I 6.9 5'5 28.2 9.6!
5.2 17.4 t4501 20.7
3.6
2.4 2.7 2.3
d
4.13"2 4.6
calcium, or lanthanum and with a different ratio of cationic and decationa~ed sections. On increasing temperature from 400 to 450 ° gasoline yield decreases for calcium catalysts, %: No. 1 by 9, No. 2 by 7, No. 3 by 5 and lanthanum sample No. 3 by 5~/o. At the same time gas yield increases by 12, 6, 6 and 7 ° , respectively. Increasing temperature from 400 to 450 ° has a most marked effect on the behaviour of the calcium catalyst sample No. 1 and results in a very sudden change in gasoline and gas yields due apparently, to the high degree of decationation of this sample. An increase in the degree of substitution by calcium and a reduction in the degree of decationation increases catalyst stability, the effect of temperature on samples Nos. 2 and 3 is therefore less marked. No special differences are evidently observed between calcium and lanthanum samples in gasoline and gas yields on changing the temperature of cracking. The temperature of cracking has the same effect on the activity of steamtreated samples as on heat-treated catalysts. The distribution of gaseous cracked products varies according to conditions of cracking and the degree of exchange by a polyvalent cation. With an increase of the temperature of cracking to 450 ° the content of CI fraction in gaseous cracked products increases on all catalysts. The lower the degree of
35
C r a c k i n g l i g h t g a s oil o n c a t a l y s t s c o n t a i n i n g zeolite
exchange by calcium, the more considerable this increase. For a degree of exchange of 22.5% by calcium the amount of C1 fraction increases approximately four-fold, for a lanthanum sample the content of this fraction also increases four times. TABLE 4. R E I ~ T I O X V B E T W E E N CRACKED P R O D U C T Y I E L D AND T H E CONTENTS OF P O L Y V A L E N T CATIONS ( W t . ~/0)
No. of sample
1 2
Cationic form
] ! I
3
i I
1
t
2 3
Cation Gasoline c o n t e n t , ~o
Gas
Coke
I Ill
III
I
Conversion
Selectivity
I III
I tli
Ca
22'5 36'7 58"0
57 54 51
68 58 55
5 5 5
3 4 3
4 4 4
3 3 3
66 63 60
74 65 61
86 86 85
92 89 90
25"6 39"7 58"5
54 53 52
71 63 60
8 i
4
La
8 7 7
4 4 5
70 67 66
79 72 71
77 79 79
90 88 85
7i5 7
6
On increasing temperature the content of fraction C2 increases in proportion to the degree of substitution by calcium. The overall amount of C2 fraction remains unchanged with an increase of temperature on lanthanum catalyst No. 3, the same way as on calcium catalyst No. 1; the overall amount of C2 fraction remains unchanged with an increase of temperature, however, ethane content is about doubled in ethane-ethylene fractions. An increase in temperature has little effect on the yield of fraction Ca T A B L E 5. C O N T E N T S C 1 - C 4 H Y D R O C A R B O N S I N GASEOUS PRODUCTS OF CRACKED GAS O I L
~TO, o f
samplo
Cationic form
ZCa
i+
~f
EC+
o
°~
1 (I) 1 (II)
2 2 3 3
(I) (II) (I) (II)
1 I 2 2 3 3
(I) (II) (I) (II) (I) (II)
Ca
La
11"4 11"6 7"5 9"5 9-6 9-9
34"0 35"8 25'7 37"4 24"8 35-6
49.7 48.5 64-2 48.0 58.1 50.3
30.4 29.6 44.1 30.3 42.5 31.1
13.7 14-1 13.5 12.7 11"0 14-1
0.5 0-4 0.5 0.7 0"6 0.5
2.4 1.4 7.3 2.7 1.0 1.5
2.2 1.7 3-6 2.5 2.4 1.9
16"4 4-2 11-5 6"8 11"5 8"4
39.4 31"6 40"5 32.6 43"2 41"7
33.7 62.9 42.4 58.3 40.1 47-6
25.7 44.1 30.3 37.8 28.2 33.4
4.7 11.1 7.7 13.5 7.7 9-0
0'6 0.8 0.6 0-3 0"6 0"5
5.0 1.9 3.6 3.3 3.7 3.3
3.7 5-6 3.2 2.8 3.2 3.1
36
L. V. KOVAL'CHUK ~t al.
and on the ratio of paraffin and olefin hydrocarbons during cracking on calcium catalysts containing zeolite. On increasing the temperature of cracking on a lanthanum sample, the overall content of fraction Ca decreases, however, the amount of propane in a propane-propylene fraction somewhat increases. The content of fraction C4 decreases noticeably on increasing the temperature of cracking on catalyst samples containing calcium (No. 1--by 15.2~/o, No. 3 - - b y 18.7%). When cracking is carried out on a lanthanum catalyst temperature has little effect on the content of fraction C4. The amount of paraffin hydrocarbons in a butane-butylene fraction decreases on all catalysts on increasing temperature. The ~ paraffins ratio is higher for a catalyst olefins containing lanthanum. Highest gasoline yield on the samples studied in the temperature range of 400-450 ° is therefore obtained at the temperature of 400 ° . The effect of temperature is directly related to the type of polyvalent cation, the degree of exchange and the ratio of cation and decationated sections. The chemical structure of a polyvalent cation has the most noticeable effect on the catalytic activity, selectivity and stability of zeolites. It was therefore interesting to observe this effect in cracking light gas oil at a temperature of 400 ° as the optimum for a series of calcium and lanthanum catalysts (Table 1). Table 4 shows results of cracking light gas oil on catalysts containing zeolite. The Table illustrates that an increase in the contents of polyvalent cations has' little influence over the activity of heat-treated catalysts containing zeolite. As a result of heat and steam treatment the overall conversion, gasoline yield and selectivity increase. Gas and coke contents decrease. This is particularly marked for samples with a high ratio of decationated and cation segments. Gasoline yield on calcium and lanthanum samples (No. 1) increases by 11 and 17%, respectively. It should be noted that an increase in the contents of cation segments results in an increased stabilization of catalysts containing zeolite and for these the tendency of increasing activity after heat and steam treatment is less marked (samples iNos. 1 and 3). Increasing the degree of substitution by a polyvalent cation reduces the activity of heat and steam-treated samples. Overall conversion and gasoline yield decrease. Thus, on increasing the degree of exchange by a polyvalent cation from about 22 to 60%, gasoline yield on calcium and lanthanum catalysts is reduced by 13 and 11~/o, respectively. Cation-decationated forms of catalysts containing zeolite with a given ratio of cationic and decationated segments are therefore highly active and selective. Calcium samples with a conversion lower t h a n t h a t of lanthanum samples are highly selective with respect to gasoline yield and produce less gas both before and after heat-steam treatment. Table 5 shows gas analysis during light gas oil cracking.
Cracking light gas oil on Catalysts containing zeolite
37
Isobutane is the main hydrocarbon in the cracked gas, its content increases with an increase of the degree of substitution by calcium and janthanum. With an increase of the degree of substitution the yield of C2 fraction decreases somewhat and the overall content of C4 fraction increases. It should be nofed that on calcium samples the amount of isobutane is higher on average than on lanthanum. However, the pattern changes after the treatment of samples with steam. The amount of isobutane decreases on catalysts containing calcium; the higher the degree of exchange by calcium, the more noticeable the reduction. Isobutane yield increases on catalysts containing lanthanum and with a reduction of the degree of exchange by lanthanum, isobutane content increases. After heat and steam treatment the effect of C2 and C3 fractions increases with an increase of the degree of substitution by calcium cations. In contrast to calcium, on lanthanum samples after heat and steam treatment, the overall contents of C2 and C3 fractions decreases in inverse proportion to the degree of exchange by lanthanum. It may be assumed that gasolines obtained using catalysts containing lanthanum, will be characterized by a large number of iso-compounds even in the liquid phase. An analysis of the composition of cracked gas shows that after heat and steam treatment the contents of saturated hydrocarbons somewhat decrease. Increasing gasoline yield and overall conversion on catalysts containing zeolite after heat and steam treatment is, apparently due to various causes. Heat and steam treatment reduces the acidity of catalysts containing zeolite [5]. Gas and coke yields decrease at the same time. In addition, heat and steam treatment intensifies the migration of cations from the crystalline into the amorphous phase of the catalyst [6] and brings aluminium into the exchange state in zeolites with low cation density. It is also possible that as a result of heat and steam treatment zeolites break down into smaller, highly active 'crystals. The complex variation of the activity of catalysts containing zeolite, which takes place by the action of heat- and heat and steam treatments is due to a whole number of causes and one cannot point out any one of them as the main cause. SUMMARY
1. Highest gasoline yield in cracking a kerosine-gas oil fraction on catalyst samples containing zeolite is achieved at a temperature of 400 °. Increasing temperature results in more intensive cracking and changes the redistributing properties of catalysts. 2. Increasing the contents of polyvalent cations has little effect on the activity of heat-treated catalysts containing zeolite, but reduces the activity of heat and steam-treated samples.
38
V . A . ZAZHIGALOVet ~ .
REFERENCES 1. L. V. KOVAL'CHUK, G. N. T.4KHTAROVA and K. V. KOPCHIYEV, Vestn. MGU, ser. khim., No. 2, 162, 1975 2. Z. S. AGAMIRZOYEVA, Karl4. dis., Baku, 1973 3. O. A. MAM~YEV and A. Z. DOROGOCHINSKII, K h i m i y a i tekhnol, topliv i masel, No. 2, 7, 1972 4. V. M. KURGANOV, A. V. AGAFONOV, M. F. SININ, G. M. GITNIK, B. G. SOLOV'YEV, B. E. KUSHNER, B. M. GAL'PERIN, A. Z. STRIZHKOV, Z. G. BELYAYEVA, V. S. KNYAZEV, V. V. MOROZOV and M. S. GUSEV, Neftepererabotka i neftekhimiya, No. 4, 3, 1973 5. L. M. VISHNEVSKAYA, Kand. dis., MGU, Moscow, 1974 6. K. V. T O P C ~ V A , A. K. GAPEYEV, T. M. IVANOV, L. N. BURENKOVA, Ya. V. MIRSKII and S. N. KHADZHIYEV, Dokl. A N SSSR 215, 384, 1974
OXIDATION OF n-BUTANE ON VANADIUM-MOLYBDENUM OXIDE CATALYSTS * V. A. ZAZHIGALOV,G. A. KOMASHKO, A. I. PYATNITSKAYAand YA. B. GOROKHOVATSK~ (dec.) L. V. Pisarzhevskii I n s t i t u t e of Physical Chemistry, Ukr.S.S.R. Academy of Sciences
(Received 22 July 1976) PARTIAL oxidation of butane to obtain maleic anhydride (MA) has recently attracted the attention of scientists. In this study a vanadium-molybdenum oxide systeni (V-Me-O) with a different ratio of components was used as catalyst in this process. This catalytic system has previously been studied ¢[1-3] in selective oxidation of benzene and other hydrocarbons to maleic anhydride. EXPERIMENTAL
V-Mo-O catalyst samples were prepared by dissolving given ammonium paramolybdate and ammonium metavanadate samples. Solutions were evaporated and the residue dried at 110°, followed by heating in air at 600 ° for 6 hr. The catalyst was then compressed, crushed and a 0.5--1.0 m m fraction was then placed in a reactor. Specific surfaces of catalysts measured according to the thermal desorption of nitrogen (Table) were similar for all the samples studied before and after operation. X-ray spectra and E P R spectra of V-Mo-O catalysts were obtained after * Neftekhimiya 17, No. 2, 268-273, 1977.