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Molecular-sieve selectivity of narrow-pore zeolites in the cracking of hydrocarbons
24
L . N . M~.ASHr~CH and A. V. P]S'M~AX'A
4. R.Z. MAGARIL, Teoreticheskiye osnovy khimicheskikh protsessov pererabotki nefti (Theoretical Principles of Chemical Petroleum Refining Processes), p. 35, Khimiya, Moscow, 1976 5. S. BENSON, Termokhimicheskaya kinetika (Thermochemical Kinetics), p. 296, Mir, Moscow, 1971 6. R. J. AKERS and J. J. THROSSELL, Trans. Faraday Soc. 63, Part I, 529, 124, 1967 7. V. N. KONDRAT'YEV, Kinetika khimicheskikh gazovykh reaktsii (Kinetics of Chemical Gas Reactions), p. 240, AN SSSR, Moscow, 1958 8. V. N. KONDRAT'YEV, Konstanty skorosti gazofaznykh reaktsii (Rate Constants of GasPhase Reactions), p. 31, Nauka, Moscow, 1971 9. Vozbuzhdeniye chastitsy v khimicheskoi kinetike (Particle Excitation in Chemical Kinetics), p. 247, Mir, Moscow, 1973
Petrol. Chem. U.S.S.R. Vol. 29, No. 1, pp. 24-29, 1989 Printed in Poland
0031-6458/89 $10.00 + .00 O 1990 Pergamon Press plc
MOLECULAR-SIEVE SELECI'IVlT~' OF NARROW-PORE ZEOLITES IN THE CRACKING OF HYDROCARBONS* L. N. M A X ~ H ~ C H and A. V. PIS'MENNAYA Institute of General and Inorganic Chemistry, Belorussian Academy of Sciences
(Received 11 April 1988)
THE use of narrow- and medium-pore zeolites as cracking catalysts has revealed one of their main features, namely their molecular-sieve effect in catalysis [1, 2]. It is largely n-hydrocarbons that are subjected to cracking because of this, leading to enrichment of the catalyst with branched and aromatic hydrocarbons. Industrial selective forming, where the narrow-pore zeolite erionite is used as the catalyst, is based on this principle [2, 3]. The aim of the present work was to conduct a comparative study of the molecular-sieve selectivity of decationated narrow-pore zeolites (mordenite, ferrierite, and erionite) in the cracking o f n-octane and a synthetic hydrocarbon mixture. The catalytic properties of mordenite and ferrierite in the cracking of hydrocarbons depend on the acid active centres and the size of the channels formed by the 12- and 8-membered and 10- and 8-membered oxygen rings respectively. The structure o f erionite contains cavities connected by 8-membered ports of 3.6 x 5-2 A diameter [4]. In the present paper use was made o f a narrow-pore modification of mordenite, the decationated form of which exhibits a molecular-sieve effect on * Neftekhimiya 29, No. 1, 52-56, 1989.
Selectivity of narrow-pore zeolites in cracking of hydrocarbons
25
benzene and n-hexane molecules, adsorbing water in a quantity similar to the magnitude of the intracrystalline volume of the pores [5]. This indicates that the larger channels formed by the 12-membered rings are inaccessible to benzene and n-hexane molecules, evidently on account of breakdowns in the crystal lattice structure during synthesis [6] or blocking of the channels by occluded matter and cations [7]. Decationated ferrierite and erionite adsorb water and n-laexane but do not adsorb benzene, and are tlaerefore also treated as narrow-pore zeolites. EXPERIMENTAL
Decationated forms of mordenite (silicate modulus x = 11.0) and erionite (x= 7.2) synthesized at the Gor'kii Experimental Works of the All-Union Scientific Research Institute for the Processing of Oil and Gases and the Production of Synthetic Liquid Fuel (VNIINP) and also ferrierite (x=23.5) synthesized by the present authors using a structure-forming additive (N-methylpyridine base) and calcined at 550°C were obtained by fourfold treatment with a 0.5 N ammol~ium chloride solution and subsequent calcination at 500°C. The degree of decationation of mordenite and ferrierite amounted to 95-96~o, and that of erionite to 91~o. The size of the crystals of the initial zeolites was determined from electron microscope pictures. Since the channel system of pores in crystals of the zeolites studied is arranged along axis c, the length of the crystals was determined. The length of mordenite crystals is 1-4 am, the length of ferrierite crystals 1-2 am, and the length of erionite crystals 1--6/tin. Cracking of n-octane and a synthetic hydrocarbon mixture was carried out in a flow-type reactor in the 400°-500°C temperature range with a volumetric flow-rate of 1-6 hr -1. For the experiments, 1-2 am zeolite fraction prepared from pelletized specimens was used. Preliminary activation and regeneration of the catalysts were carried out at 550°C for 3 hr using dried air with subsequent lowering of the temperature to experimental temperature and blowing with dried nitrogen for 0.5 hr. Cracking was carried out on a fresh activated catalyst at a prescribed temperature for 0.5 hr, and then the specimen was regenerated, after which cracking was carried out again for 0.5 hr with reaction product samples taken for analysis. The composition of the gaseous and liquid cracking products was determined by means of GLC. The synthetic hydrocarbon mixture contained 16.9 wt.Yo n-hexane, 26.3 wt.~. benzene, 3.4 wt.~o isooctane, 31.4 wt.~o toluene, and 22.0 wt.yo n-octane. DISCUSSION OF RESULTS
The results of testing decationated erionite (NE), mordenite (NM), and ferrierite (NF) in the cracking of n-octane are given in Table 1. The degree of transformation of n-octane on NM and NE in the 400°-500°C temperature range changed little with increase in temperature, but its transformation on NF increased from 57.9 to 67.5 ~o. The greatest conversion of n-octane (69.7~/~) was achieved on NE at 500°C; on N F and N M it was slightly lower.
26
L; N. MALASHeVlCn and A. V. I~'bm,rNAYA
Differences in the selectivity of the zeolites studied can be traced from the composition of the cracking products k~f n-hexane (Table 1). A distinguishing feature of the action of decationated erionite and ferrierite is that largely propane-propylene fraction is formed on them, while on NM it is largely aliphatic hydrocarbons C6 TAm~
I. COMPOSITION OF CRACKING PRODUCTS (w'r.~ AND DEORI~ OF TRANSFORMATION o ~ n-ocTASe (~)
Aliphatic hydrocarbons
t,
°C Cs
NE
0 9 0 0 p 29 p: j 09 6 1
Ce
0
500
69"7 1"5
3"2
5"4 48"6
0"8 N
9.8
2"5 18"0[ 0.2
400 450 500
63-3 0"6 65"8 1"4 63"3 2'2
0'2 0"4 0"7
1"4] 27"9 3"4 27.4 5-I 29"0
7"8[ 23"9 8"4[ 21"4 9"3 ~.[F15"8
6-5 30"3[0"4 5"6 29"81 0'4 4.2 31"51 0'7
450 500
59-6[ 2"1 67"5] 4"0
4"1 7"1
10"5 28.9 15"4[ 32.2
3"1 3.2
17.3 18"3
14"6 18"7 0"4 8"2 11'0 0"4
1"0 1"2 1"3
0"2 0"2
0.3 0.2
that are formed. From the data of Table 1 it is evident that aromatization occurs on N M and N F with the formation of small quantities of benzene. Furthermore, on N M isomerization of n-octane to isooctane is observed. On zeolite NE, benzene (0.2 wt. ~o) is found only in products of n-octane conversion at 500°C. The formation of small quantities of benzene and isooctane evidently occurs on the external surface of crystals of the zeolites studied, since the size of the channels (5.5 x 4.5 A for TABLE 2. MATERIAL BALANCE (WT. ~') OF CRACKING OF SYNTHETIC HYDROCARBON MIXTURE t, °C
Catalysate yield
Yield of gaseous products
Coke +losses
20.0 29,2 28.2
8.4 6.5 7-7
15-5 16-8 23"9
9"3 9"6 9"0
t, °C
Cata|ysate yield
°l °J 450 5OO
450 "
NM 75-2 73.6 67.1
I
Coke +losses
NF
NE 71.6 64.3 64.1
Yield of gaseous products
40O 450 500
75"9 75"2 67'5
17"4 19"7 26.2
6"7 5"I 6.3
27
Selectivityof narrow-pore zeolites in cracking of hydrocarbons
ferrierite) is small for diffusion of these molecules from the intracrystalline space of ferrierite and erionite, while the channels of mordenite are inaccessible to molecules of n-octane by virtue of the factors indicated above. During cracking of a synthetic hydrocarbon mixture on the given zeolites, greatest gas formation is observed on zeolite NE, and lowest gas formation on NM (Table 2). In the gaseous cracking products on all three zeolites the predominant fraction is propane-propylene (Table 3), the content of which, like the content of isobutanebutene fraction, decreases with increase in temperature from 400 ° to 500°C. At the same time there is an increase in the content of ethane-ethylene fraction and methane, especially on NF. From the data of Table 3 it follows that gaseous products are formed as a result of cracking of n-hydrocarbons (n-hexane and n-octane), since their content in the catalysate is reduced. As in the case of cracking of individual n-octane, greatest conversion of n-hydrocarbons from the mixture is observed on NE, and then on NF. TABI~ 3. C O ~ O S r n O N ot~ CAT.aJ.YSXTe A N D OASnOUS C~ACr,J N O PRODUCTS Or m ' m t o c ~ t a O N (wt.%)
Gaseous products
Catalysate
i o~
NE 400 I 0"8 1-9 1-6173"01I , 122-71.8 20-41.5 450 I 1"2 3"6 3.5 71.31 500 2"8 5.9 6"3 66.8I 18.2 1"3 NM [ 22.915.5 - 11"8 4450 0 0 1 -4"4J 0"9 1"7 -7"2 63"8 63"9 I'0 500 3"0 2.4 15"5 54.5 15"4 0"4 NF 400 [ 7.3 5"8 24"6 45"9 6"9 9"5]1"51 450 9.8 8"8 25"1 42"2 3"8 10.3 1"31 500 16.7 14"0 28.7 31.1 1"4 8.4 I
6-4 4.7 10"9
I
1.011
8-6131"2
5"2 36"91 9"9 7"3 32.8 5-7 39"9 8"1 7"4 31"5 5"3 37"3 6-3
m
I
4"1 3"7 1"3
16.7[ 27"3 3"1 28"0 17"0 2"0 16"229.3 2"5 30"415"9 1"0 15.228.7 2"7 32"7 18"0 1.0
3"0 3"0 2"3
12"3128"614"0 34"516"1 ] 8.329.64.3 37-2 14"9 1"5 5.7 32.2 4"1 40"6 13"1 1"0 m
Thus, in the 400°-500°C temperature range, the n-hexane content of the mixture falls by 50-57 wt. ~. after cracking on NE, and its n-octane content by 55-71 wt. ~.; on N F the content of these hydrocarbons falls by 28-66 and 27--40 wt. ~. respectively. On decationated mordenite, the n-hexane content of the catalyst falls considerablyless (1-10wt. ~.)than its n-octane content (18--28 wt. ~); there is also a reduction in the isooetane content, which may be attributed to its cracking, despite a possible increase in its content on account of isomerization of n-octane to iso-
octane. In addition there is an increase in the benzene and toluene contents of the hydro-
28
L . N . MALAS~WCrl and A. V. Pm'Mm~AYA
carbon mixture after cracking on the given zeolites, and also in the isooctane content on NE and NF. Furthermore, xylenes are formed in small quantity (1-2 wt. ~o) on zeolites N M and NF. Thus, obtained data on the cracking of a hydrocarbon mixture on decationated forms of mordenite, ferrierite, and erionite indicate that the concentration of aromatic hydrocarbons and isostructural hydrocarbons occurs on account of cracking of n-structural hydrocarbons, although to different extents on the different zeolites. A comparison of data on the cracking of n-octane and a hydrocarbon mixture indicates that, despite the similar degrees of transformation of individual n-octane on the zeolites studied, cracking of n-hydrocarbons from the hydrocarbon mixture proceeds in different ways. The selectivity of these zeolites in the cracking of hydrocarbons is evidently affected not only by the accessibility of the acid centres in the structure of the zeolites, but also by the composition of the hydrocarbon feedstock. The presence of branched and aromatic hydrocarbons in the hydrocarbon mixture has almost no effect on the activity of zeolite NE in the cracking of n-hydrocarbons, it slightly reduces the activity of zeolite NF, and suppresses considerably the activity of N M in this reaction. This may be attributed to the fact that cracking of nhydrocarbons of NE and NF largely occurs on acid centres of the internal surface of channels, while on NM it largely occurs on acid centres of the external surface of crystals, which are accessible not only to n-structural molecules, but also to isoand aromatic hydrocarbons. Despite the fact that the SiO2/AI~O3 ratio in erionite is considerably lower than in ferrierite, its activity is slightly higher than that of ferrierite. This is probably due to the influence of the crystal length of the zeolites. Ferrierite is noted for a more uniform length ofcrystals (1-2/am); in erionite, crystals of 4--5/Ira length predominate, and in mordenite, crystals of 3--4/~m length. Molecules of n-paraffins, entering the channels, will remain in them for longer in the case of erionite than in the case of ferrierite, on account of which there is a greater probability of collision with active eentres and their cracking. As shown by calculation of the material balance of cracking of the hydrocarbon mixture (Table 2), this assumption is borne out by the greater gas formation on NE. SUMMARY
1. A comparative study has been made of the molecular-sieve selectivity of deeationated zeolites mordenite, ferrierite, and erionite in the cracking of hydrocarbons. 2. The catalysts tesfed have similar activity in the cracking of individual n-octane. This is not the case in the cracking of n-hydrocarbons from a hydrocarbon mixture. 3. Greatest activity in the selective cracking of n-hydrocarbons from their mixture with aromatic and branched hydrocarbons is exhibited by decationated erionite, and then by ferrierite. The narrow-pore modification of mordenite has low activity in the selective cracking of n-hydrocarbons from a hydrocarbon mixture.
N-mono-and N,N.dialkanoylacctamides as additives to lubricants
29
REFERENCES 1. Z. M. CHICHERI, Khimiya tseolitov i kataliz na tseolitakh (Chemistry of Zeolites and Catalysis on Zeolites), Part 2, p. 296, Mir, Moscow, 1980 2. N. J. CHEN and W. E. GARWOOD, Catal. Rev. Sci. Engng. 28, 2-3, 155, 1986 3. M. M. KUKOVITSKII, N. P. DAGAYEV, L. G. SUSHKO, F. Kh. URAZAYEV, V. Yu. GEORGIYEVSKH, G. N. MASLYANSKII, V. V. SHIPIKIN and A. B. ROZENBLIT, Neftepererabotka i neftekhimiya, 9, 29, 1978 4. D. BREK, Tseolitnye molekulyarnye sita (Zeolite Molecular Sieves), 791, pp., Mir, Moscow, 1976 5. L. N. MALASHEVICH, V. S. KOMAROV and A. B. PIS'MENNAYA, Vestsi AN BSSR Ser. khim. nauk, 6, 21, 1987 6. F. RAATZ, C. MARCILLY and E. FREUND, Zeolites 5, 5, 329, 1985 7. E. E. SENDEROV and N. I. KHITAROV, Tseolity, ikh sintez i usloviya obrazovaniya v prirode (Zeolites, Their Synthesis, and Conditions of Their Natural Formation), p. 118, Nauka, Moscow, 1970
Petrol. Chem. U.S.S.R. Vol. 29, No. I, pp. 29-34, 1989 Printed in Poland
0031-6458/S9 Sio.o0+.o0
O 199oPergamonPnm ple
N-MONO- AND N,N-DIALKANOYLACET.AMIDES AND THEIR THIO ANALOGUES AS ADDITIVES TO LUBRICANTS* A. B. K t a . l ~ v , M. M. DZ~VADOV, O. A. ~ and T. SrL GASANOYA
v
Institute of Chemistry of Additives, Azerbaidzhan Academy of Sciences (Received 27 June 1988)
Tt-m results of earlier investigations have shown that amides o f thiocarboxylic, diethyldithiocarbaminic, and isopropylxanthogenic acids are effective additives to lubricants [1-51. In order to find more effective additives, in the present paper N - m o n o - and N,N-dialkanoylacetamides and their thio analogues were synthesized, and their effect on the qua}ity o f lubricants was investigated. These investigations are also of interest in that they make it possible to study the comparative effectiveness of primary, secondary, and tertiary amides and thioamides as additives to lubricants. ~aN-Mono- and N,N-dialkanoylacetamides were synthesized by the reaction o f acetamide with c,arboxylic acid chloiides; in turn the latter were obtained by the * Neftekh;m;ya 29, No. 1, 96-100, 1989.
L . N . M~.ASHr~CH and A. V. P]S'M~AX'A
4. R.Z. MAGARIL, Teoreticheskiye osnovy khimicheskikh protsessov pererabotki nefti (Theoretical Principles of Chemical Petroleum Refining Processes), p. 35, Khimiya, Moscow, 1976 5. S. BENSON, Termokhimicheskaya kinetika (Thermochemical Kinetics), p. 296, Mir, Moscow, 1971 6. R. J. AKERS and J. J. THROSSELL, Trans. Faraday Soc. 63, Part I, 529, 124, 1967 7. V. N. KONDRAT'YEV, Kinetika khimicheskikh gazovykh reaktsii (Kinetics of Chemical Gas Reactions), p. 240, AN SSSR, Moscow, 1958 8. V. N. KONDRAT'YEV, Konstanty skorosti gazofaznykh reaktsii (Rate Constants of GasPhase Reactions), p. 31, Nauka, Moscow, 1971 9. Vozbuzhdeniye chastitsy v khimicheskoi kinetike (Particle Excitation in Chemical Kinetics), p. 247, Mir, Moscow, 1973
Petrol. Chem. U.S.S.R. Vol. 29, No. 1, pp. 24-29, 1989 Printed in Poland
0031-6458/89 $10.00 + .00 O 1990 Pergamon Press plc
MOLECULAR-SIEVE SELECI'IVlT~' OF NARROW-PORE ZEOLITES IN THE CRACKING OF HYDROCARBONS* L. N. M A X ~ H ~ C H and A. V. PIS'MENNAYA Institute of General and Inorganic Chemistry, Belorussian Academy of Sciences
(Received 11 April 1988)
THE use of narrow- and medium-pore zeolites as cracking catalysts has revealed one of their main features, namely their molecular-sieve effect in catalysis [1, 2]. It is largely n-hydrocarbons that are subjected to cracking because of this, leading to enrichment of the catalyst with branched and aromatic hydrocarbons. Industrial selective forming, where the narrow-pore zeolite erionite is used as the catalyst, is based on this principle [2, 3]. The aim of the present work was to conduct a comparative study of the molecular-sieve selectivity of decationated narrow-pore zeolites (mordenite, ferrierite, and erionite) in the cracking o f n-octane and a synthetic hydrocarbon mixture. The catalytic properties of mordenite and ferrierite in the cracking of hydrocarbons depend on the acid active centres and the size of the channels formed by the 12- and 8-membered and 10- and 8-membered oxygen rings respectively. The structure o f erionite contains cavities connected by 8-membered ports of 3.6 x 5-2 A diameter [4]. In the present paper use was made o f a narrow-pore modification of mordenite, the decationated form of which exhibits a molecular-sieve effect on * Neftekhimiya 29, No. 1, 52-56, 1989.
Selectivity of narrow-pore zeolites in cracking of hydrocarbons
25
benzene and n-hexane molecules, adsorbing water in a quantity similar to the magnitude of the intracrystalline volume of the pores [5]. This indicates that the larger channels formed by the 12-membered rings are inaccessible to benzene and n-hexane molecules, evidently on account of breakdowns in the crystal lattice structure during synthesis [6] or blocking of the channels by occluded matter and cations [7]. Decationated ferrierite and erionite adsorb water and n-laexane but do not adsorb benzene, and are tlaerefore also treated as narrow-pore zeolites. EXPERIMENTAL
Decationated forms of mordenite (silicate modulus x = 11.0) and erionite (x= 7.2) synthesized at the Gor'kii Experimental Works of the All-Union Scientific Research Institute for the Processing of Oil and Gases and the Production of Synthetic Liquid Fuel (VNIINP) and also ferrierite (x=23.5) synthesized by the present authors using a structure-forming additive (N-methylpyridine base) and calcined at 550°C were obtained by fourfold treatment with a 0.5 N ammol~ium chloride solution and subsequent calcination at 500°C. The degree of decationation of mordenite and ferrierite amounted to 95-96~o, and that of erionite to 91~o. The size of the crystals of the initial zeolites was determined from electron microscope pictures. Since the channel system of pores in crystals of the zeolites studied is arranged along axis c, the length of the crystals was determined. The length of mordenite crystals is 1-4 am, the length of ferrierite crystals 1-2 am, and the length of erionite crystals 1--6/tin. Cracking of n-octane and a synthetic hydrocarbon mixture was carried out in a flow-type reactor in the 400°-500°C temperature range with a volumetric flow-rate of 1-6 hr -1. For the experiments, 1-2 am zeolite fraction prepared from pelletized specimens was used. Preliminary activation and regeneration of the catalysts were carried out at 550°C for 3 hr using dried air with subsequent lowering of the temperature to experimental temperature and blowing with dried nitrogen for 0.5 hr. Cracking was carried out on a fresh activated catalyst at a prescribed temperature for 0.5 hr, and then the specimen was regenerated, after which cracking was carried out again for 0.5 hr with reaction product samples taken for analysis. The composition of the gaseous and liquid cracking products was determined by means of GLC. The synthetic hydrocarbon mixture contained 16.9 wt.Yo n-hexane, 26.3 wt.~. benzene, 3.4 wt.~o isooctane, 31.4 wt.~o toluene, and 22.0 wt.yo n-octane. DISCUSSION OF RESULTS
The results of testing decationated erionite (NE), mordenite (NM), and ferrierite (NF) in the cracking of n-octane are given in Table 1. The degree of transformation of n-octane on NM and NE in the 400°-500°C temperature range changed little with increase in temperature, but its transformation on NF increased from 57.9 to 67.5 ~o. The greatest conversion of n-octane (69.7~/~) was achieved on NE at 500°C; on N F and N M it was slightly lower.
26
L; N. MALASHeVlCn and A. V. I~'bm,rNAYA
Differences in the selectivity of the zeolites studied can be traced from the composition of the cracking products k~f n-hexane (Table 1). A distinguishing feature of the action of decationated erionite and ferrierite is that largely propane-propylene fraction is formed on them, while on NM it is largely aliphatic hydrocarbons C6 TAm~
I. COMPOSITION OF CRACKING PRODUCTS (w'r.~ AND DEORI~ OF TRANSFORMATION o ~ n-ocTASe (~)
Aliphatic hydrocarbons
t,
°C Cs
NE
0 9 0 0 p 29 p: j 09 6 1
Ce
0
500
69"7 1"5
3"2
5"4 48"6
0"8 N
9.8
2"5 18"0[ 0.2
400 450 500
63-3 0"6 65"8 1"4 63"3 2'2
0'2 0"4 0"7
1"4] 27"9 3"4 27.4 5-I 29"0
7"8[ 23"9 8"4[ 21"4 9"3 ~.[F15"8
6-5 30"3[0"4 5"6 29"81 0'4 4.2 31"51 0'7
450 500
59-6[ 2"1 67"5] 4"0
4"1 7"1
10"5 28.9 15"4[ 32.2
3"1 3.2
17.3 18"3
14"6 18"7 0"4 8"2 11'0 0"4
1"0 1"2 1"3
0"2 0"2
0.3 0.2
that are formed. From the data of Table 1 it is evident that aromatization occurs on N M and N F with the formation of small quantities of benzene. Furthermore, on N M isomerization of n-octane to isooctane is observed. On zeolite NE, benzene (0.2 wt. ~o) is found only in products of n-octane conversion at 500°C. The formation of small quantities of benzene and isooctane evidently occurs on the external surface of crystals of the zeolites studied, since the size of the channels (5.5 x 4.5 A for TABLE 2. MATERIAL BALANCE (WT. ~') OF CRACKING OF SYNTHETIC HYDROCARBON MIXTURE t, °C
Catalysate yield
Yield of gaseous products
Coke +losses
20.0 29,2 28.2
8.4 6.5 7-7
15-5 16-8 23"9
9"3 9"6 9"0
t, °C
Cata|ysate yield
°l °J 450 5OO
450 "
NM 75-2 73.6 67.1
I
Coke +losses
NF
NE 71.6 64.3 64.1
Yield of gaseous products
40O 450 500
75"9 75"2 67'5
17"4 19"7 26.2
6"7 5"I 6.3
27
Selectivityof narrow-pore zeolites in cracking of hydrocarbons
ferrierite) is small for diffusion of these molecules from the intracrystalline space of ferrierite and erionite, while the channels of mordenite are inaccessible to molecules of n-octane by virtue of the factors indicated above. During cracking of a synthetic hydrocarbon mixture on the given zeolites, greatest gas formation is observed on zeolite NE, and lowest gas formation on NM (Table 2). In the gaseous cracking products on all three zeolites the predominant fraction is propane-propylene (Table 3), the content of which, like the content of isobutanebutene fraction, decreases with increase in temperature from 400 ° to 500°C. At the same time there is an increase in the content of ethane-ethylene fraction and methane, especially on NF. From the data of Table 3 it follows that gaseous products are formed as a result of cracking of n-hydrocarbons (n-hexane and n-octane), since their content in the catalysate is reduced. As in the case of cracking of individual n-octane, greatest conversion of n-hydrocarbons from the mixture is observed on NE, and then on NF. TABI~ 3. C O ~ O S r n O N ot~ CAT.aJ.YSXTe A N D OASnOUS C~ACr,J N O PRODUCTS Or m ' m t o c ~ t a O N (wt.%)
Gaseous products
Catalysate
i o~
NE 400 I 0"8 1-9 1-6173"01I , 122-71.8 20-41.5 450 I 1"2 3"6 3.5 71.31 500 2"8 5.9 6"3 66.8I 18.2 1"3 NM [ 22.915.5 - 11"8 4450 0 0 1 -4"4J 0"9 1"7 -7"2 63"8 63"9 I'0 500 3"0 2.4 15"5 54.5 15"4 0"4 NF 400 [ 7.3 5"8 24"6 45"9 6"9 9"5]1"51 450 9.8 8"8 25"1 42"2 3"8 10.3 1"31 500 16.7 14"0 28.7 31.1 1"4 8.4 I
6-4 4.7 10"9
I
1.011
8-6131"2
5"2 36"91 9"9 7"3 32.8 5-7 39"9 8"1 7"4 31"5 5"3 37"3 6-3
m
I
4"1 3"7 1"3
16.7[ 27"3 3"1 28"0 17"0 2"0 16"229.3 2"5 30"415"9 1"0 15.228.7 2"7 32"7 18"0 1.0
3"0 3"0 2"3
12"3128"614"0 34"516"1 ] 8.329.64.3 37-2 14"9 1"5 5.7 32.2 4"1 40"6 13"1 1"0 m
Thus, in the 400°-500°C temperature range, the n-hexane content of the mixture falls by 50-57 wt. ~. after cracking on NE, and its n-octane content by 55-71 wt. ~.; on N F the content of these hydrocarbons falls by 28-66 and 27--40 wt. ~. respectively. On decationated mordenite, the n-hexane content of the catalyst falls considerablyless (1-10wt. ~.)than its n-octane content (18--28 wt. ~); there is also a reduction in the isooetane content, which may be attributed to its cracking, despite a possible increase in its content on account of isomerization of n-octane to iso-
octane. In addition there is an increase in the benzene and toluene contents of the hydro-
28
L . N . MALAS~WCrl and A. V. Pm'Mm~AYA
carbon mixture after cracking on the given zeolites, and also in the isooctane content on NE and NF. Furthermore, xylenes are formed in small quantity (1-2 wt. ~o) on zeolites N M and NF. Thus, obtained data on the cracking of a hydrocarbon mixture on decationated forms of mordenite, ferrierite, and erionite indicate that the concentration of aromatic hydrocarbons and isostructural hydrocarbons occurs on account of cracking of n-structural hydrocarbons, although to different extents on the different zeolites. A comparison of data on the cracking of n-octane and a hydrocarbon mixture indicates that, despite the similar degrees of transformation of individual n-octane on the zeolites studied, cracking of n-hydrocarbons from the hydrocarbon mixture proceeds in different ways. The selectivity of these zeolites in the cracking of hydrocarbons is evidently affected not only by the accessibility of the acid centres in the structure of the zeolites, but also by the composition of the hydrocarbon feedstock. The presence of branched and aromatic hydrocarbons in the hydrocarbon mixture has almost no effect on the activity of zeolite NE in the cracking of n-hydrocarbons, it slightly reduces the activity of zeolite NF, and suppresses considerably the activity of N M in this reaction. This may be attributed to the fact that cracking of nhydrocarbons of NE and NF largely occurs on acid centres of the internal surface of channels, while on NM it largely occurs on acid centres of the external surface of crystals, which are accessible not only to n-structural molecules, but also to isoand aromatic hydrocarbons. Despite the fact that the SiO2/AI~O3 ratio in erionite is considerably lower than in ferrierite, its activity is slightly higher than that of ferrierite. This is probably due to the influence of the crystal length of the zeolites. Ferrierite is noted for a more uniform length ofcrystals (1-2/am); in erionite, crystals of 4--5/Ira length predominate, and in mordenite, crystals of 3--4/~m length. Molecules of n-paraffins, entering the channels, will remain in them for longer in the case of erionite than in the case of ferrierite, on account of which there is a greater probability of collision with active eentres and their cracking. As shown by calculation of the material balance of cracking of the hydrocarbon mixture (Table 2), this assumption is borne out by the greater gas formation on NE. SUMMARY
1. A comparative study has been made of the molecular-sieve selectivity of deeationated zeolites mordenite, ferrierite, and erionite in the cracking of hydrocarbons. 2. The catalysts tesfed have similar activity in the cracking of individual n-octane. This is not the case in the cracking of n-hydrocarbons from a hydrocarbon mixture. 3. Greatest activity in the selective cracking of n-hydrocarbons from their mixture with aromatic and branched hydrocarbons is exhibited by decationated erionite, and then by ferrierite. The narrow-pore modification of mordenite has low activity in the selective cracking of n-hydrocarbons from a hydrocarbon mixture.
N-mono-and N,N.dialkanoylacctamides as additives to lubricants
29
REFERENCES 1. Z. M. CHICHERI, Khimiya tseolitov i kataliz na tseolitakh (Chemistry of Zeolites and Catalysis on Zeolites), Part 2, p. 296, Mir, Moscow, 1980 2. N. J. CHEN and W. E. GARWOOD, Catal. Rev. Sci. Engng. 28, 2-3, 155, 1986 3. M. M. KUKOVITSKII, N. P. DAGAYEV, L. G. SUSHKO, F. Kh. URAZAYEV, V. Yu. GEORGIYEVSKH, G. N. MASLYANSKII, V. V. SHIPIKIN and A. B. ROZENBLIT, Neftepererabotka i neftekhimiya, 9, 29, 1978 4. D. BREK, Tseolitnye molekulyarnye sita (Zeolite Molecular Sieves), 791, pp., Mir, Moscow, 1976 5. L. N. MALASHEVICH, V. S. KOMAROV and A. B. PIS'MENNAYA, Vestsi AN BSSR Ser. khim. nauk, 6, 21, 1987 6. F. RAATZ, C. MARCILLY and E. FREUND, Zeolites 5, 5, 329, 1985 7. E. E. SENDEROV and N. I. KHITAROV, Tseolity, ikh sintez i usloviya obrazovaniya v prirode (Zeolites, Their Synthesis, and Conditions of Their Natural Formation), p. 118, Nauka, Moscow, 1970
Petrol. Chem. U.S.S.R. Vol. 29, No. I, pp. 29-34, 1989 Printed in Poland
0031-6458/S9 Sio.o0+.o0
O 199oPergamonPnm ple
N-MONO- AND N,N-DIALKANOYLACET.AMIDES AND THEIR THIO ANALOGUES AS ADDITIVES TO LUBRICANTS* A. B. K t a . l ~ v , M. M. DZ~VADOV, O. A. ~ and T. SrL GASANOYA
v
Institute of Chemistry of Additives, Azerbaidzhan Academy of Sciences (Received 27 June 1988)
Tt-m results of earlier investigations have shown that amides o f thiocarboxylic, diethyldithiocarbaminic, and isopropylxanthogenic acids are effective additives to lubricants [1-51. In order to find more effective additives, in the present paper N - m o n o - and N,N-dialkanoylacetamides and their thio analogues were synthesized, and their effect on the qua}ity o f lubricants was investigated. These investigations are also of interest in that they make it possible to study the comparative effectiveness of primary, secondary, and tertiary amides and thioamides as additives to lubricants. ~aN-Mono- and N,N-dialkanoylacetamides were synthesized by the reaction o f acetamide with c,arboxylic acid chloiides; in turn the latter were obtained by the * Neftekh;m;ya 29, No. 1, 96-100, 1989.