c
I
A
I
13 5 Minute Unknown
I I I
I I
-
I I I
weight in the range 250-300. The rich mixture of peaks in the SnC12 run (Figure 2) between naphthalene and the "13.5-min unknown" presumably represenh low-boiling products in the oil, derived from the SRC with SnClz catalyst. It is noteworthy that these peaks are almost absent in the Co/Mo/Al208 run (Figure 3). As pointed out above, the chromatogram shown in Figure 2 is consistent with the high Hz consumption and the very low material balances when SnClz is used. Oil constituents with retention times longer than 13.5 min a t 270 "C, the highest temperature chosen for use with the OV-101 columns, would not have been detected; the GC analysis was terminated a t this point.
Figure 3. Chromatogram of oil fraction from run 3A.
Acknowledgment The authors are grateful to the Energy Research and Development Administration and to the Hooker Chemical Co. obtained on the oil fractions. Figure 2 is for the oil from Run for partial support of this research. D. Elmore and M. LaRosa 2A (SnC12);Figure 3 is for the oil from Run 3A (Co/Mo/Al~o~). established the solubility of SRC in various solvents; Miss E. In both cases there was some residual (unstripped) solvent, Rabcewicz and C. Orcheski measured the molecular weights typically a mixture of tetralin and naphthalene. In both cases of oil and asphaltene samples. P. Ho and J. Scinta provided there was a major, sharp peak with a retention time of 13.5 min continuous advice and assistance. (at 270 "C) in this temperature-programmed chromatogram. Literature Cited The identity of this component is unresolved. However, corKawa, W., Friedman, S.,Wu, W. R. K., Frank, L. V., Yavorsky, P. M.. 167th Narelations of relative retention time vs. carbon number and vs. tional Meeting of the American Chemical Society, Los Angeles, Calif., Mar normal boiling point were used to predict that the 13.5-min 31-Apr 5, 1974. peak could correspond to a compound analogous to an alkane Lovetro, 0.C., M. S. Thesis, Department of Chemical Engineering, State University of New York at Buffalo, April 1977. of carbon number C20-C21 and a normal boiling point of ca. Weller, S.,Pelipetz, M. G., Roc. 3rd Worldfetrol. Cong., Sect. IV, Subsect. 1, 365 "C. The sharpness of the peak and the estimated carbon 91 (1951a). Weller, S., Pelipetz, M. G., lnd. Eng. Chem., 43, 1243 (1951b). number make it tempting to attribute the peak to some diYen, Y. K., Furlani, D. E., Weller, S. W., lnd. Eng. Chem., Prod. Res. Dev., 15, meric ke., (320, with M N 260) species originating from the 24 (1976). tetralin solvent, and not from the SRC. Our determinations, by vapor-phase osmometry, of the molecular weight of the Received for review June 27,1977 total oil fractions routinely showed an average molecular Accepted August 8,1977
Neopentyl Polyol Ester Lubricants-Boundary
Composition Limits
Edmund L. Niedrieiskl E. 1. du font de Nemours & Company, Petroleum Laboratory, Wilmington, Delaware 19898
Composition limits for mixed pentaerythritol/dipentaerythritol (PE/diPE) esters of various normal carboxylic acids were defined by a method that simultaneously satisfies the product specifications on viscosity (210 and -40 O F ) , volatility (flash point), and low-temperature flow (pour point). The boundaries were represented in terms of PE and diPE molecular weights, mixed ester molecular weight, and molar concentrations of carboxylic acids. The 210 O F viscosity specification was generally the most restrictive on product ester molecular weight, averaging between 566 and 629. The -40 O F viscosity specification imposed an upper limit on the diPE content. This analysis was carried out separately using data obtained on mixtures of odd-numbered(C,,CT,and Cd,evennumbered (C4, c g , and C8 or cg, C8,and Clo), and consecutively-numbered (C, to C9)normal carboxylic acids.
Introduction The flexibility in the physical properties.of the neopentyl poly01 ester lubricants was shown to be due to the redistri300
Ind. Eng. Chem., Prod. Res. Dev., Vol. 16, No. 4, 1977
bution phenomenon which takes place during the synthesis of the ester (Gunderson and Hart, 1962; Niedzielski, 1976). The functionality of the polyol was found to have a greater
Table I. Specifications on Bulk Properties of Neopentyl Poly01 Ester Lubricants
PWA-521C Viscosity, cSt at 500 OF at 400 OF at 210 OF at 100 OF at -40 O F Pour point, OF Flash point, OF
MIL-L23699B(2)
...
... ...
1.0 min
5.5 max 100 max 13 000 max -75 max' 400 rnin
MIL-L27502 1.0 min
5.0-5.5 25 rnin 13 000 max -65 max 475 rnin
... ... ...
15 000 max -65 max 475 rnin
effect on the bulk properties than the number of mixed ester compounds in the redistribution mixture. T o determine the range of compositions of mixed esters that would actually satisfy the product specifications given in Table I, composition limits for mixed pentaerythritol/dipentaerythritol (PE/diPE) were determined in terms of the mixed poly01 molecular weight, product ester molecular weight, and molar concentrations of carboxylic acids.
Procedure for Defining Composition Limits Mixtures of PE/diPE and several classes of carboxylic acid mixtures were studied. These classes are identified as follows. Class identification
Normal carboxylic acids
Data
C B ,C I , and Cg cq,c6,and C S or c6, C S , and C I O CB, c6, c7,CS, c9
Table I1 Table I11
1 2
3
A description of the relationships between lubricant properties and composition variables was obtained by means of an empirical model (Draper and Smith, 1966). Models of the general form of eq 1were found to be adequate for such description. In eq 1, Y represents the lubricant properties (viscosities, etc.), X 1 = PE/diPE (polyol) average molecular weight, X 2 = mixed ester molecular weight, X 3 = molar concentration (%) of a specific carboxylic acid, and the E's are coefficients estimated through the use of the above model and the data of Tables 11-IV. Y = Bo + B l X l + B2Xz + B3X3 + BlzX1X2 t B23X2B3 BllX1' BzzX2'
+
+
The poly01 molecular weights, X I , corresponding to the PE/diPE mixtures used in the study are given in Table V. The product molecular weight, X z , is calculated using eq 2, where 7 = poly01 functionality, f i = molar concentration of carboxylic acid C i , and wi = molecular weight of carboxylic acid Ci.
[(
xZ= x1+
if=f4 i
wi)
- 18]
(2)
The use of eq 1to represent lubricant property vs. composition relationships can be described as a multidimensional mathematical procedure analogous to that of using a French curve to draw a smooth trend line on a two-dimensional X-Y plot. Separate models were used for each set of data (cf. Tables 11-IV). The specific model forms used for each carboxylic acid class are identified in Appendix I. The criterion used for estimating the coefficients was least squares, which minimizes the sum of squares of the difference (data value minus smoothed value) over all data points. Equation 1 was also used to provide a representation of carbon number = average number of carbon atoms corresponding to each carboxylic acid mixture used. For example, the carbon number for a mixture containing 30% Cg, 50% C7, and 20% Cg equals 0.3(5) 0.5(7) 0.2(9) = 6.8.
+
Table IV
+ B13X1X3 + B33X3' (1)
+
Table 11. Composition and Property Data Cg, C,, and CSCarboxylic Acid Esters Mol 96 PE 1
diPE
100.0
0.0
93.2
6.8
85.55
14.45
81.5 16.87 66.9 66.9
18.5 23.13 33.1 33.1
2 3 4 5 6 7 8
9 10 11
12 13 14 15 16 17 18
19 20 21 22 23 24 25 26 27
c5
c 7
C9
7
MW
cSt at 210°F
20.0 20.0 20.0 40.0 33.3 10.0 5.0 50.0 20.0 25.0 22.0 20.0 25.0 30.0 25.0 35.0 45.0 30.0 45.0 45.0 45.0 60.0 32.0
60.0 20.0 50.0 20.0 33.3 80.0 90.0
20.0 60.0 30.0 40.0 33.3 10.0 5.0 50.0 20.0 25.0 18.0 10.0 15.0 20.0 27.0 25.0 35.0 10.0 25.0 15.0 15.0 20.0 8.0 10.0
4.00
585 630 590 585 585 585 585 585 608 608 603 598 598 598 612 598 598 585 585 574 598 586 606 647 596 599 586
5.11 5.51 5.19 5.03 5.05 4.91 4.90 4.98 5.25 5.32 5.18 5.26 5.16 5.20 5.38 5.20 5.25 5.05 5.12 4.964 5.35 5.21 5.31 5.83 5.41 5.72 5.67
10.0
60.0 80.0 90.0
0.0
60.0 50.0 60.0 70.0 60.0 50.0 48.0 40.0 20.0 60.0 30.0 40.0 40.0 20.0 60.0 80.0 30.0 10.0 5.0
10.0
10.0 5.0
4.14
4.29 4.37 4.46 4.66 4.66
cSt at -40°F
Pour point, OF
Flash point, OF
9600 Solid Solid Solid Solid 6838 6913 Solid 8106 8129 8028 9360 7819 7857 8727 8200 8136 7463 7692 7394 8737 8310 8759
-65.0 -10.0 -40.0 -40.0 -40.0 -55.0 -55.0 -25.0 -65.0 -65.0 -65.0 -65.0 -65.0 -65.0 -60.0 -65.0 -65.0 -70.0
