- Email: [email protected]
Kinetic regularities of oxidation of some aircraft oil bases
18
V. V. T~AR~TONOV e t a / .
having stable activity, was 70.5%. On ASK in this case the Value was 13-3% with an overall conversion of 15.6%. On comparing catalysts according to the formation of an ortho-isomer, in case of stable activity, over 80% 2-~-MBP is formed on Zeokar-2. Results therefore indicate that AShNTs-3 and Zeokar-2 industrial catalysts containing zeolite are effective and have high ortho-orientation ability in arylalkylation of phenol with styrene. SUMMARY
1. AShNTs-3 and Zeokar-2 industrial catalysts containing zeolite have higher activity and selectivity in arylalkylation of phenol with styrene than ASK catalysts. 2. Heat and steam treatment of catalysts containing zeolite reduces polymerization properties and stabilizes activity. REFERENCES
1. M. V. KURASHEV, B. Y. ROMANOVSK11 and N. Y. KOLESI~ICHENKO, Nef~khimlya 17, 507, 1977 2. T. G. VERETYAKHINA, M. V. KURASHEV, G. M. MAMEDALIYEV, N. V. KOLESNICHENKO a n d A. Yu. KOSHEVNIK, Zh. organ, khimii 10, 359, 1974 3. L. P. KIRYAKINA, M. N. ZHAVORONKOV a n d A. Z. DOROGOCHINSKII, Zh. fiz. khimii 50, 503, 1976 4. K. V. TOPCHIYEV, KHO SHI TYUANG, Vestn. mosk. un-ta, K h i m i y a No. 2, 221, 1974 5. Kh. M. MINACHEV, Ya. I. ISAKOV, V. P. KALININ, A. L. LAPIDUS and Ya. T. EIDUS, Izv. AN SSSR, Ser. khim., 1334, 1974
0031-6458/78/0101-0018507.50]0
Petrol. Chem.U.S.S.R.Vol. 18, pp. 18-25. (~ PergamonPress Ltd. 1979.Printed in Poland
KINETIC REGULARITIES OF OXIDATION OF SOME AIRCRAFT OIL BASES* V. V. KHARITONOV, V. A. ]~ORISOV a n d O. A. Z~OROZ~SKAYA
(Received 18 August
1977)
THE development of heat-stable synthetic lubricants is an urgent problem of petro]eum chemistry. It is recommended to use polyhydrie alcohol esters and aliphatie carboxylic acids and aliphatic dicarboxylic acid diesters [1, 2] as bases for forming heat-stable oils. * Neftekhhnlya 18, No. 1, 112-117, 1978.
Oxidation of some aircraf~ oil bases
18
For the scientifically sound selection of aircraft oil bases it is essential to know the k~netics and mechanism of initial stages of oxidation. This paper is concerned with the study of kinetic regularities of oxidation of C5-C 9 monocarboxylic acid pentaerythritol ester (PE), di-iso-oetyl ester of sebacic acid (DOS) and MK-8 mineral oil. EXPERIMENTAL
The following aircraft oil bases were used for the study: MK-8 (GOST 6457-66), p 0.8782 g/eros; DOS, p 0.9154 g/cm3; PE, p 0.9917 g/cm s. Commercial pentaerythritol esters of various types (PEV), (PEL) and (PEU) were used in the study. l~ates of auto- and initiated oxidation were determined from oxygen absorption using a balancing pressure gauge. Dicumyl peroxide was the initiator, which ensured during the experiments a constant rate of formation of radicals 1¥~ in the temperature-range of 100140 °. The rate constant of initiation (k~) in the medium of the bases used was assumed to be kt in high pressure polyethylene [3]. Investigations were carried out at a temperature of 120 ° and oxygen was the oxidizing agent (absolute value of P ~ I atm). The reaction volume (1 ml) was heated for 5 to 7 rain and the initiator was added to the system after heating. RESULTS
Oxygen absorption after initiation should be considered during oxidation in the case of short chain length. Since the value of v is fairly high (between 6 and 30) in the system examined, according to a conventional system of oxidation [6], the rate of oxidation is described by the formula (1): W=k2" [RH]. [ROll,
(1)
i.e. depends on the rate constant of'chain extension/c2 and tlm concentration of peroxide radicals [ROll. According to the method of stationary concentrations, the latter is determined by the ratio
where WI is the overall rate of radical formation, equal to the total rate o f radical formation from the initiator (W~) and the rate of radical formation from the substratum (W~0); k6 is the rate constant of recombination of radicals [RO'~]. Since the ratio of k~[RH] is a constant value for each substance under given conditions, denoting it by a we obtain
W---a. ~/W~+W~o
(~)
V. V. KIL~RITONOVet al.
20
Using formula (2) it is convenient to compare oxidation properties of various :substances. I t is sufficient to measure parameters a and W~0, which can be :readily determined if oxidation is not carried out under conditions of auto,oxidation, b u t b y an unbranched chain reaction, using for example the method o f initiators. Figure 1 shows the relation between W ~ for the materials studied and the value of W~. It can be seen from Fig. 1 that this relationship is complex and n o t linear, as required b y formula (2). It is evident that, in contrast to indivi-
0
I
2
3
Wi ~I0 z, mole/L.sec Fro. 1
'0
1000
200g
% sec
FIG. 2
FzG. 1. Dependence of the square of the initial rate of oxidation of pentaerythritol esters on the rate of initiation: 1--MK-8; 2--PEL; 3--PEV; 4--PEU; 5--DOS. ?Fro. 2. Kinetic curves of oxygen absorption: 1--MK-8; 2--PEL; 3--PEV; 4--PEU; 5--DOS; 6--C~Hs,. dual hydrocarbons, bases of oils contain substances, which can slow down or accelerate oxidation. In this case kinetics of oxygen absorption b y oxidizing bases will not be linear. Figure 2 shows kinetic curves of oxygen absorption b y the bases examined at 120 ° and with W ~ 1 × 10 -6 mole/1..sec. An analysis of curves indicates that initial rates of oxidation of aircraft oil bases are considerably lower than the rate of oxidation of ClsH3~ hydrocarbon. Furthermore, oxidation is clearly auto-catalytic. As time passes the rate of oxidation tends to a constant limiting value Wnm. I f we assume that auto-acceleration in initiated oxidation of hydrocarbons is due to a gradual reduction of inhibitor content, the value of W~ being given, it is easy to determine parameter a from the value of Wnm (W~0 may be ignored, since W~0<
Oxidation of some aircraft oil bases
21
Parameter a~W~o m a y be evaluated diagrammatically from the segment intersected on the ordinate (Fig. 1). Table 1 gives a comparison of a values for the bases examined. To calculate [RH] average molecular weights of substrata were used. To calculate the a v e r Wllm " I0 s,mo/e/l..~eo
15
(we2-w,')'/o~,rno/e//.,eec
"
5
g
0
i i ! 0"5 1.0 1.5 v~#7.1~, ,.o/e '/~ ll. ',~ . 3.~ '/,
FIG. 3
0
I
2
3
w,. . I ~ mo/efl..~ec Fro. 4
FIG. 3. Relationship between the limiting rate of oxidation Wlim and X / ~ : 1--MK-8~ 2--PEL; 3--PEV; 4--PEU; 5--DOS. FIG. 4. Relationship between the difference of the initial ra¢~ of oxidation and the rate of initiation (W--W,) and the rate of initiation W, : 1--MK-8; 2--PEL; 3--PEV; 4--PEU; 5--DOS. age molecular weight of pentaerythritol ester, a formula with a length of t h e acid part of ester of 7 carbon atoms, was used. Experimental results indicate that the bases examined m a y be arranged in the following order in their ability to undergo oxidation (under conditions. of initiated oxidation): MK-8~DOS~PEV~PEL~PEU. MK-8 mineral oil is oxidized to a lesser extent under these conditions (120 °) than DOS and PE. This oil consists of aromatic compounds ( ~ 16%) and paraffinic-naphthenic compounds (~75~o). The value of (/c2/~/~) for MK-8 oil is close to that obtained for reactive fuels containing about 80% naphthene fraction and is in satisfactory agreement with results in the literature concerning individual hydrocarbons (Table 1) [3, 4, 8]. The value of ]c2/x/~-~obtained for P E is 4.5-fold higher than the value k n o w n for pentaerythritol tetravalerate [4, 5], which m a y be explained b y an increase in the number of methylene groups in the acid part of ester. At 120 ° partial rate constants in terms of one ester fragment for P E and diethylene glycol dicaprylate [4, 5] are about 2 × 10 -S.
•2
V.
V , K H A R I T O N O V 8t a~o
Parameter k~/x/~ for DOS is somewhat higher ( ~ 1.7-fold) than for di-isobutyladipate [6], which may be due to an increase in the number of methylene groups in the acid and alcoholic parts for DOS. TABLE 1. PARAMETER a AT 120°C
[RH],
Base
MK-8 DOS PEL PEU PEV Iso-oetane n-Decane Cyclohexane H i g h pressure polyethylene
(mole/1. • sec)*
mole/1.
1"1~0"05 1"3±0.05 1"2i0"05 1-5~0.05 1"0±0.05
3.125 2"149 1"698 1"698 1"698
- -
×
10 s
References
(L/see. mole) ~ u
3"6~0"05 5"9-~0"05 7"0±0"05 8"5-t- 0"05 6-1=1=0'05 1-2 1"5 11"0
m
13] [3] I-4] 15]
0"41
kl * a ~ "~--~-, " [ R H ] × 10 ~.
It is clear, however, that oxidation properties of bases cannot adequately be characterized by parameter / ¢ ~ / ~ , since advanced stages of oxidation can only be compared, when oxidation properties are only determined by composition and parameter a (/ca of the gross process and k 6of the gross proc,ess). Initial stages of oxidation are not described by the system [6] and rate TABLE 2. VALUES OF W AND V OF OXIDATION Base or hydrocarbon MK-8 DOS PEV PEL PEU Cyclohexano Tetralin Isopropylbenzene Benzaldehyde
T, °C 120 120 120 120 120 100 50 100 25
W × 10 e, mole/1., sec
W~ × 106, mole/1., see
23-6.58 22-6"44 18.2-5.14 20.7-6.11 20.2-7.15
4-0.33 3-0.26 3-0.24 2.98-0"26 3-0.24
v 7-20 7-26 6-21 7-24 8-30 525 140 16"6 1050
is not given by formula (2). Table 2 compares initial rates and the chain length v of oxidation of hydrocarbons [7] and aircraft oil bases. It can be seen that the chain length of oxidation of the bases studied is fairly considerable (v>2) and features of oxidation of bases previously noted suggest t h e presence of inhibitors [ Intt] in the system. If the system contains I n H and
Oxidation of some aircraft oil bases
23
all chains undergo linear rupture, W,----2k7[InH] [R0,] and the rate of oxidation t~kes the form: k~.[RH] W~ W= W~+ 2kT[ini_i] (3) Consequently, a linear relatiou is observed between (W--W,) and W~. Figure 4 [(W--W,)-~f(W,)] shows that a linear relation holds good; this is in agreement with the assumption concerning the presence of InH in the bases. TABLE 3. PARAMETERP , FOR AIRCRAFT TABLE 4. VALUE O F / [ I n H]0 FOR ~RCR~FT Om OIL BASES AT 120°C BASES (120°C) Base
MK-8 DOS PEL PEU PEV
Base
P~ × 103 (mole/1.. sec)* 3.64-0.05 1.64-0"05 2.6±0.05 1.3 ± 0"05 0.94-0.05
f [ I n H] × 1 0 5 , mole/1.
[In H] × 105, mole/1. (at f = 2)
337.5 54.0 77"5
168-7 27.0 38-7
MK-8 DOS PEL
Oxidation of hydrocarbons in the presence of InH is described by system (I) I n H ~ l ~ O ~ k, I n ' ~ R 0 0 H I n ' ~ R 0 ~ ~", molecular products
(I)
According to systems [6] and (I), if rupture of R0~ takes place by the reactions given kT[InH] [In']stat = (a) ks W ~
~
W
W,--k6~[~-H]2=2kTEInI~k2i~-H] Wnm= k~[RH]/7;7 x/~ v vv~ (rate of oxidation without InH)
(b) (c)
Replacing k2[RH] according to equation (c) and substituting it in equation (b) we obtain the following formula:
Wlim W--=F---- ,2k7 [Intt]. W
Wlim
~/k6 WI[
The inhibiting effect may be characterized by kinetic parameter p
2k7 I:~-~A [InH]
(4)
V. V. K~.A.RITONOVet
24
al.
Parameter P1 is normally de~ermined from the dependence of the rate of consumption InH on concentration [7]. Since we are unable to vary InH content in the system, parameter Pa is determined diagrammatically from the dependence of F on 1/~/-W, (Fig. 5). Table 3 shows calculated values of parameter P1 for the substrata examined. The concentration of an unknown inhibitor in the substrata studied was also determined (from induction periods) (Table 4). r
0
0-5
l.O
1-5
( ¢W[)-I ,10-~, mote'~.t.'/~, sec'/= FIG. 5. l~elationship between 2' and 1/X/~: 1--MK-8; 2--PEL; 3--PEV; 4--PEU; 5--DOS. It follows from experimental results (Table 3) that the bases examined may be arranged in the following order based on the inhibiting effect of InH (accordin~ to parameter P1) MK-8>PEL:>DOS > P E U > P E V MK-8 mineral oil, which contains an inhibitor with the highest inhibiting effect, is the most stable under these conditions (at 120°C). The authors are grateful to Ye. T. Denisov for his help in discussing experimental results and conclusions. SUMMARY
1. Methods were proposed for determining parameters, which give a quantitative description of initial stages of oxidation of mineral (MK-8) and synthetic (di-iso-octyl sebacate (DOS), pentaerythric ethers (PE)) aircraft oil bases. Aircraft oil bases occupy the following order in their ability to oxidize MK-8PEL>DOS>PEU>PEV
Lubricating properties of hydrocarbons of oil fractions
25,
REFERENCES 1. R. S. GUNDERSON a n d A. V. KItORT, Sinteticheskiye smazochnyye m a t e r i a l y i zhidkosti (Synthetic Lubricants and Liquids). K h i m i y a , Moscow, 1965 2. T. M. ITSIKSON, M. B. RAPOPORT and V. N. MIKHEYEV, K h i m i y a i t e k h n o l o g i y a topliv i masel, No. 4, 34, 1969 3. V. V. FEDOROVA a n d V. V. KHARITONOV, K i n e t i k a i kataliz 15, 866, 1974 4. G. G. AGLIULLINA, V. S. MARTEM'YANOV, Ye. T. DENISOV, O. A. KULAGINA a n d M. M. KUKOVITSKII, l~eftekhimiya 16, 262, 1976 5. G. G. AGLIULLINA, V. S. MARTEM'YANOV, Ye. T. DENISOV and T. I. YELISEYEVA, Izv. A_~ SSSR, Ser. khim., 50, 1977 6. Ye. T. DENISOV, N. L MITSKEVICH and V. Ye. AGABEKOV, Mekhanizm zhidkofaznogo okisleniya kislorodosoderzhashchikh soyedinenii (Liquid-Phase O x i d a t i o n Mechanism of Compounds Containing Oxygen). N a u k a i tekhnika, Minsk, 1975 7. N. M. EMANUEL', Ye. T. DENISOV and Z. K. MAIZUS, Tsepnyye reaktsii o k i s l e n i y a uglevodorodov v zsidkoi faze (Liquid-Phase Chain Reactions of Oxidation of H y d r o carbons). Nauka, Moscow, 1965 8. G. I. KOVALEV, L. D. GOG1TIDZE, V. I. KURANOVA and Ye. T. DENISOV, Neftek h i m i y a 17, 3, 1977
Petrol. Chem. U.S.S.R. Vol. 18, pp. 25-30. (~) Pcrgamon Press Ltd. 1979. Printed in Poland
0031-6458/78/0101-0025507.50[@,
RELATIONSHIP BETWEEN LUBRICATING PROPERTIES OF HYDROCARBONS OF OIL FRACTIONS AND THEIR ADSORPTION PROPERTIES ON METAL* G. I. K i c n x i ~ and A. A. MARKOV (Received 28 July 1976)
.ADsoRPTION of lubricants by metal surfaces is of considerable significance ir~ technology. I t is assumed that in the majority of cases the wear of friction surfaces with boundary lubrication is prevented as a rpsult of the adsorption of lubricant constituents or additives, which under high conditions of friction are converted from adsorbed layers into chemically modified ones. It is assumed t h a t the more intensive the adsorption, the more effectively the lubricant protects the friction surface from wear [1-3]. From this p o i n t of view it was interesting to examine the adsorption properties of individual groups of hydrocarbons contained in mineral oils in relation to metals. To solve this problem we used two methods: measurements of electron release energy (EI~.E) of the metal [3] and adsorption heat using a continuoua calorimeter [4]. * Neftekhimiya 18, No. 1, 133-137, 1978.
V. V. T~AR~TONOV e t a / .
having stable activity, was 70.5%. On ASK in this case the Value was 13-3% with an overall conversion of 15.6%. On comparing catalysts according to the formation of an ortho-isomer, in case of stable activity, over 80% 2-~-MBP is formed on Zeokar-2. Results therefore indicate that AShNTs-3 and Zeokar-2 industrial catalysts containing zeolite are effective and have high ortho-orientation ability in arylalkylation of phenol with styrene. SUMMARY
1. AShNTs-3 and Zeokar-2 industrial catalysts containing zeolite have higher activity and selectivity in arylalkylation of phenol with styrene than ASK catalysts. 2. Heat and steam treatment of catalysts containing zeolite reduces polymerization properties and stabilizes activity. REFERENCES
1. M. V. KURASHEV, B. Y. ROMANOVSK11 and N. Y. KOLESI~ICHENKO, Nef~khimlya 17, 507, 1977 2. T. G. VERETYAKHINA, M. V. KURASHEV, G. M. MAMEDALIYEV, N. V. KOLESNICHENKO a n d A. Yu. KOSHEVNIK, Zh. organ, khimii 10, 359, 1974 3. L. P. KIRYAKINA, M. N. ZHAVORONKOV a n d A. Z. DOROGOCHINSKII, Zh. fiz. khimii 50, 503, 1976 4. K. V. TOPCHIYEV, KHO SHI TYUANG, Vestn. mosk. un-ta, K h i m i y a No. 2, 221, 1974 5. Kh. M. MINACHEV, Ya. I. ISAKOV, V. P. KALININ, A. L. LAPIDUS and Ya. T. EIDUS, Izv. AN SSSR, Ser. khim., 1334, 1974
0031-6458/78/0101-0018507.50]0
Petrol. Chem.U.S.S.R.Vol. 18, pp. 18-25. (~ PergamonPress Ltd. 1979.Printed in Poland
KINETIC REGULARITIES OF OXIDATION OF SOME AIRCRAFT OIL BASES* V. V. KHARITONOV, V. A. ]~ORISOV a n d O. A. Z~OROZ~SKAYA
(Received 18 August
1977)
THE development of heat-stable synthetic lubricants is an urgent problem of petro]eum chemistry. It is recommended to use polyhydrie alcohol esters and aliphatie carboxylic acids and aliphatic dicarboxylic acid diesters [1, 2] as bases for forming heat-stable oils. * Neftekhhnlya 18, No. 1, 112-117, 1978.
Oxidation of some aircraf~ oil bases
18
For the scientifically sound selection of aircraft oil bases it is essential to know the k~netics and mechanism of initial stages of oxidation. This paper is concerned with the study of kinetic regularities of oxidation of C5-C 9 monocarboxylic acid pentaerythritol ester (PE), di-iso-oetyl ester of sebacic acid (DOS) and MK-8 mineral oil. EXPERIMENTAL
The following aircraft oil bases were used for the study: MK-8 (GOST 6457-66), p 0.8782 g/eros; DOS, p 0.9154 g/cm3; PE, p 0.9917 g/cm s. Commercial pentaerythritol esters of various types (PEV), (PEL) and (PEU) were used in the study. l~ates of auto- and initiated oxidation were determined from oxygen absorption using a balancing pressure gauge. Dicumyl peroxide was the initiator, which ensured during the experiments a constant rate of formation of radicals 1¥~ in the temperature-range of 100140 °. The rate constant of initiation (k~) in the medium of the bases used was assumed to be kt in high pressure polyethylene [3]. Investigations were carried out at a temperature of 120 ° and oxygen was the oxidizing agent (absolute value of P ~ I atm). The reaction volume (1 ml) was heated for 5 to 7 rain and the initiator was added to the system after heating. RESULTS
Oxygen absorption after initiation should be considered during oxidation in the case of short chain length. Since the value of v is fairly high (between 6 and 30) in the system examined, according to a conventional system of oxidation [6], the rate of oxidation is described by the formula (1): W=k2" [RH]. [ROll,
(1)
i.e. depends on the rate constant of'chain extension/c2 and tlm concentration of peroxide radicals [ROll. According to the method of stationary concentrations, the latter is determined by the ratio
where WI is the overall rate of radical formation, equal to the total rate o f radical formation from the initiator (W~) and the rate of radical formation from the substratum (W~0); k6 is the rate constant of recombination of radicals [RO'~]. Since the ratio of k~[RH] is a constant value for each substance under given conditions, denoting it by a we obtain
W---a. ~/W~+W~o
(~)
V. V. KIL~RITONOVet al.
20
Using formula (2) it is convenient to compare oxidation properties of various :substances. I t is sufficient to measure parameters a and W~0, which can be :readily determined if oxidation is not carried out under conditions of auto,oxidation, b u t b y an unbranched chain reaction, using for example the method o f initiators. Figure 1 shows the relation between W ~ for the materials studied and the value of W~. It can be seen from Fig. 1 that this relationship is complex and n o t linear, as required b y formula (2). It is evident that, in contrast to indivi-
0
I
2
3
Wi ~I0 z, mole/L.sec Fro. 1
'0
1000
200g
% sec
FIG. 2
FzG. 1. Dependence of the square of the initial rate of oxidation of pentaerythritol esters on the rate of initiation: 1--MK-8; 2--PEL; 3--PEV; 4--PEU; 5--DOS. ?Fro. 2. Kinetic curves of oxygen absorption: 1--MK-8; 2--PEL; 3--PEV; 4--PEU; 5--DOS; 6--C~Hs,. dual hydrocarbons, bases of oils contain substances, which can slow down or accelerate oxidation. In this case kinetics of oxygen absorption b y oxidizing bases will not be linear. Figure 2 shows kinetic curves of oxygen absorption b y the bases examined at 120 ° and with W ~ 1 × 10 -6 mole/1..sec. An analysis of curves indicates that initial rates of oxidation of aircraft oil bases are considerably lower than the rate of oxidation of ClsH3~ hydrocarbon. Furthermore, oxidation is clearly auto-catalytic. As time passes the rate of oxidation tends to a constant limiting value Wnm. I f we assume that auto-acceleration in initiated oxidation of hydrocarbons is due to a gradual reduction of inhibitor content, the value of W~ being given, it is easy to determine parameter a from the value of Wnm (W~0 may be ignored, since W~0<
Oxidation of some aircraft oil bases
21
Parameter a~W~o m a y be evaluated diagrammatically from the segment intersected on the ordinate (Fig. 1). Table 1 gives a comparison of a values for the bases examined. To calculate [RH] average molecular weights of substrata were used. To calculate the a v e r Wllm " I0 s,mo/e/l..~eo
15
(we2-w,')'/o~,rno/e//.,eec
"
5
g
0
i i ! 0"5 1.0 1.5 v~#7.1~, ,.o/e '/~ ll. ',~ . 3.~ '/,
FIG. 3
0
I
2
3
w,. . I ~ mo/efl..~ec Fro. 4
FIG. 3. Relationship between the limiting rate of oxidation Wlim and X / ~ : 1--MK-8~ 2--PEL; 3--PEV; 4--PEU; 5--DOS. FIG. 4. Relationship between the difference of the initial ra¢~ of oxidation and the rate of initiation (W--W,) and the rate of initiation W, : 1--MK-8; 2--PEL; 3--PEV; 4--PEU; 5--DOS. age molecular weight of pentaerythritol ester, a formula with a length of t h e acid part of ester of 7 carbon atoms, was used. Experimental results indicate that the bases examined m a y be arranged in the following order in their ability to undergo oxidation (under conditions. of initiated oxidation): MK-8~DOS~PEV~PEL~PEU. MK-8 mineral oil is oxidized to a lesser extent under these conditions (120 °) than DOS and PE. This oil consists of aromatic compounds ( ~ 16%) and paraffinic-naphthenic compounds (~75~o). The value of (/c2/~/~) for MK-8 oil is close to that obtained for reactive fuels containing about 80% naphthene fraction and is in satisfactory agreement with results in the literature concerning individual hydrocarbons (Table 1) [3, 4, 8]. The value of ]c2/x/~-~obtained for P E is 4.5-fold higher than the value k n o w n for pentaerythritol tetravalerate [4, 5], which m a y be explained b y an increase in the number of methylene groups in the acid part of ester. At 120 ° partial rate constants in terms of one ester fragment for P E and diethylene glycol dicaprylate [4, 5] are about 2 × 10 -S.
•2
V.
V , K H A R I T O N O V 8t a~o
Parameter k~/x/~ for DOS is somewhat higher ( ~ 1.7-fold) than for di-isobutyladipate [6], which may be due to an increase in the number of methylene groups in the acid and alcoholic parts for DOS. TABLE 1. PARAMETER a AT 120°C
[RH],
Base
MK-8 DOS PEL PEU PEV Iso-oetane n-Decane Cyclohexane H i g h pressure polyethylene
(mole/1. • sec)*
mole/1.
1"1~0"05 1"3±0.05 1"2i0"05 1-5~0.05 1"0±0.05
3.125 2"149 1"698 1"698 1"698
- -
×
10 s
References
(L/see. mole) ~ u
3"6~0"05 5"9-~0"05 7"0±0"05 8"5-t- 0"05 6-1=1=0'05 1-2 1"5 11"0
m
13] [3] I-4] 15]
0"41
kl * a ~ "~--~-, " [ R H ] × 10 ~.
It is clear, however, that oxidation properties of bases cannot adequately be characterized by parameter / ¢ ~ / ~ , since advanced stages of oxidation can only be compared, when oxidation properties are only determined by composition and parameter a (/ca of the gross process and k 6of the gross proc,ess). Initial stages of oxidation are not described by the system [6] and rate TABLE 2. VALUES OF W AND V OF OXIDATION Base or hydrocarbon MK-8 DOS PEV PEL PEU Cyclohexano Tetralin Isopropylbenzene Benzaldehyde
T, °C 120 120 120 120 120 100 50 100 25
W × 10 e, mole/1., sec
W~ × 106, mole/1., see
23-6.58 22-6"44 18.2-5.14 20.7-6.11 20.2-7.15
4-0.33 3-0.26 3-0.24 2.98-0"26 3-0.24
v 7-20 7-26 6-21 7-24 8-30 525 140 16"6 1050
is not given by formula (2). Table 2 compares initial rates and the chain length v of oxidation of hydrocarbons [7] and aircraft oil bases. It can be seen that the chain length of oxidation of the bases studied is fairly considerable (v>2) and features of oxidation of bases previously noted suggest t h e presence of inhibitors [ Intt] in the system. If the system contains I n H and
Oxidation of some aircraft oil bases
23
all chains undergo linear rupture, W,----2k7[InH] [R0,] and the rate of oxidation t~kes the form: k~.[RH] W~ W= W~+ 2kT[ini_i] (3) Consequently, a linear relatiou is observed between (W--W,) and W~. Figure 4 [(W--W,)-~f(W,)] shows that a linear relation holds good; this is in agreement with the assumption concerning the presence of InH in the bases. TABLE 3. PARAMETERP , FOR AIRCRAFT TABLE 4. VALUE O F / [ I n H]0 FOR ~RCR~FT Om OIL BASES AT 120°C BASES (120°C) Base
MK-8 DOS PEL PEU PEV
Base
P~ × 103 (mole/1.. sec)* 3.64-0.05 1.64-0"05 2.6±0.05 1.3 ± 0"05 0.94-0.05
f [ I n H] × 1 0 5 , mole/1.
[In H] × 105, mole/1. (at f = 2)
337.5 54.0 77"5
168-7 27.0 38-7
MK-8 DOS PEL
Oxidation of hydrocarbons in the presence of InH is described by system (I) I n H ~ l ~ O ~ k, I n ' ~ R 0 0 H I n ' ~ R 0 ~ ~", molecular products
(I)
According to systems [6] and (I), if rupture of R0~ takes place by the reactions given kT[InH] [In']stat = (a) ks W ~
~
W
W,--k6~[~-H]2=2kTEInI~k2i~-H] Wnm= k~[RH]/7;7 x/~ v vv~ (rate of oxidation without InH)
(b) (c)
Replacing k2[RH] according to equation (c) and substituting it in equation (b) we obtain the following formula:
Wlim W--=F---- ,2k7 [Intt]. W
Wlim
~/k6 WI[
The inhibiting effect may be characterized by kinetic parameter p
2k7 I:~-~A [InH]
(4)
V. V. K~.A.RITONOVet
24
al.
Parameter P1 is normally de~ermined from the dependence of the rate of consumption InH on concentration [7]. Since we are unable to vary InH content in the system, parameter Pa is determined diagrammatically from the dependence of F on 1/~/-W, (Fig. 5). Table 3 shows calculated values of parameter P1 for the substrata examined. The concentration of an unknown inhibitor in the substrata studied was also determined (from induction periods) (Table 4). r
0
0-5
l.O
1-5
( ¢W[)-I ,10-~, mote'~.t.'/~, sec'/= FIG. 5. l~elationship between 2' and 1/X/~: 1--MK-8; 2--PEL; 3--PEV; 4--PEU; 5--DOS. It follows from experimental results (Table 3) that the bases examined may be arranged in the following order based on the inhibiting effect of InH (accordin~ to parameter P1) MK-8>PEL:>DOS > P E U > P E V MK-8 mineral oil, which contains an inhibitor with the highest inhibiting effect, is the most stable under these conditions (at 120°C). The authors are grateful to Ye. T. Denisov for his help in discussing experimental results and conclusions. SUMMARY
1. Methods were proposed for determining parameters, which give a quantitative description of initial stages of oxidation of mineral (MK-8) and synthetic (di-iso-octyl sebacate (DOS), pentaerythric ethers (PE)) aircraft oil bases. Aircraft oil bases occupy the following order in their ability to oxidize MK-8
Lubricating properties of hydrocarbons of oil fractions
25,
REFERENCES 1. R. S. GUNDERSON a n d A. V. KItORT, Sinteticheskiye smazochnyye m a t e r i a l y i zhidkosti (Synthetic Lubricants and Liquids). K h i m i y a , Moscow, 1965 2. T. M. ITSIKSON, M. B. RAPOPORT and V. N. MIKHEYEV, K h i m i y a i t e k h n o l o g i y a topliv i masel, No. 4, 34, 1969 3. V. V. FEDOROVA a n d V. V. KHARITONOV, K i n e t i k a i kataliz 15, 866, 1974 4. G. G. AGLIULLINA, V. S. MARTEM'YANOV, Ye. T. DENISOV, O. A. KULAGINA a n d M. M. KUKOVITSKII, l~eftekhimiya 16, 262, 1976 5. G. G. AGLIULLINA, V. S. MARTEM'YANOV, Ye. T. DENISOV and T. I. YELISEYEVA, Izv. A_~ SSSR, Ser. khim., 50, 1977 6. Ye. T. DENISOV, N. L MITSKEVICH and V. Ye. AGABEKOV, Mekhanizm zhidkofaznogo okisleniya kislorodosoderzhashchikh soyedinenii (Liquid-Phase O x i d a t i o n Mechanism of Compounds Containing Oxygen). N a u k a i tekhnika, Minsk, 1975 7. N. M. EMANUEL', Ye. T. DENISOV and Z. K. MAIZUS, Tsepnyye reaktsii o k i s l e n i y a uglevodorodov v zsidkoi faze (Liquid-Phase Chain Reactions of Oxidation of H y d r o carbons). Nauka, Moscow, 1965 8. G. I. KOVALEV, L. D. GOG1TIDZE, V. I. KURANOVA and Ye. T. DENISOV, Neftek h i m i y a 17, 3, 1977
Petrol. Chem. U.S.S.R. Vol. 18, pp. 25-30. (~) Pcrgamon Press Ltd. 1979. Printed in Poland
0031-6458/78/0101-0025507.50[@,
RELATIONSHIP BETWEEN LUBRICATING PROPERTIES OF HYDROCARBONS OF OIL FRACTIONS AND THEIR ADSORPTION PROPERTIES ON METAL* G. I. K i c n x i ~ and A. A. MARKOV (Received 28 July 1976)
.ADsoRPTION of lubricants by metal surfaces is of considerable significance ir~ technology. I t is assumed that in the majority of cases the wear of friction surfaces with boundary lubrication is prevented as a rpsult of the adsorption of lubricant constituents or additives, which under high conditions of friction are converted from adsorbed layers into chemically modified ones. It is assumed t h a t the more intensive the adsorption, the more effectively the lubricant protects the friction surface from wear [1-3]. From this p o i n t of view it was interesting to examine the adsorption properties of individual groups of hydrocarbons contained in mineral oils in relation to metals. To solve this problem we used two methods: measurements of electron release energy (EI~.E) of the metal [3] and adsorption heat using a continuoua calorimeter [4]. * Neftekhimiya 18, No. 1, 133-137, 1978.