Energy & Fuels 2005, 19, 625-628
625
Characterization of Polar Components in the UV-Irradiated Hytrotreated Naphthenic Rubber Base Oil Sheng Han,† Chao Qiu,† Xingguo Cheng,‡ Shujie Ma,§ and Tianhui Ren*,† School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, P.R. China, Research and Development Center of PetroChina Lubricating Oil Company, Lanzhou 730060, P.R. China, and Research and Development Center of PetroChina Lubricating Oil Company, Kelemayi 934003, P.R. China Received July 15, 2004. Revised Manuscript Received December 8, 2004
In this paper, polar components in the UV-irradiated hydrotreated naphthenic rubber base oil were analyzed in detail. First, polar components were isolated from the base oil by silica gel column chromatography, and then they were characterized by a series of instrumental techniques, including elemental analysis, infrared spectroscopy, APCI/MS, and XPS. The results of the tests indicate that polar components comprise some aromatic heteroatom compounds of oxygen, sulfur, and nitrogen. Oxygen-containing compounds such as hydroxyl, carbonyl, and carboxyl groups constitute the main body of polar components. Nitrogen-containing compounds (NH2, NH, or NO2 and -NdN-) and sulfur-containing compounds (SO42- and sulfoxides) only account for minor percent of polar components. The molecular weight distribution of polar components is mainly concentrated between 200 and 500.
1. Introduction Rubber oil as a kind of industrial oil is used in a wide range of applications in compounding rubber. It might act as a plasticizer, softening the rubber polymer. Hydrotreated naphthenic rubber base oil produced by the Kelemayi refinery is a new series of health-friendly products.1 In comparison with the conventional solvent refining rubber base oil, it has many excellent merits, such as a high viscosity index, low volatility loss, low aromatic content, and the like.1-5 Particularly due to increased concerns over health and the environment in recent years, the demand for the kind of material has increased rapidly. Unfortunately, hydrotreated naphthenic rubber base oil suffers from the shortcoming that it would tend toward poor stability against ultraviolet light degradation and rapidly discolor when exposed to ultraviolet radiation or sunlight.2-10 This poor stability makes it not meet stringent performance requirements * Author to whom correspondence should be addressed. Tel: 8621-54747118. Fax: 86-21-54741297. E-mail:
[email protected]. † Shanghai Jiao Tong University. ‡ PetroChina Lubricating Oil Company, Lanzhou. § PetroChina Lubrication Oil Company, Kelemayi. (1) Gao, H.; Yang J. Lubr. Oil 2002, 17, 57-63. (2) Huang, W.; Zu, D.; Shi, Y.; Chen, Y.; Liu, G. Acta Petr. Sin., Petr. Process. Sect. 2000, 16, 31-37. (3) Kartzmark, R.; Gilbert, J. B. Hydrocarbon Process. 1967, 46, 143-148. (4) Ushio, M.; et al. ACS Div. Petr. Chem. Inc. Preprints 1992, 37, 1293-1302. (5) Galiano-Roth, N.; Page, M. Lubr. Eng. 1994, 50, 659-664. (6) Zakarian, J. A.; Robson, R. J.; Farrell, T. R. Energy Prog. 1987, 7, 1. (7) Landis, M. E.; Murphy, W. R. Lubr. Eng. 1991, 47, 595-598. (8) Murray, D. W.; MacDonald, J. M.; White, A. M.; Wright, P. G. Proc. 11th World Petr. Congr. London, 1983. (9) Gilbert, J. B.; et al. World Petr. Congr. Proc. 1971, 4, 147-157. (10) Li, C.; Jia, C. Lubr. Oil 2000, 15, 47-51.
of advanced white rubber products, consequently lowering its commercial value. So it is very necessary to research its light stability so as to find effective means to overcome such a disadvantage. For common hydrotreated oil, many workers have testified that a simple, effective, and plausible research method for oil sampling is to analyze sediment formed during ultraviolet radiation so as to better understand the problem of light stability.11,12 However, a very interesting phenomenon is observed for hydrotreated naphthenic rubber base oil. Although it discolors intensely during ultraviolet radiation, no sediment forms such as with common hydrotreated oil; the reason is that all photooxidized products are easy to dissolve in the oil sample because of inherent good solubility of naphthenic base oil. These photooxidized products appear in the polar components. Thus, researching polar components in the UV-irradiated hydrotreated naphthenic rubber base oil could yield similar results to researching sediments of common hydrotreated oil formed during ultraviolet radiation. In this paper, polar components in the UV-irradiated hydrotreated naphthenic rubber base oil were analyzed. Polar components were isolated from the base oil by silica gel column chromatography and then characterized by a series of instrumental techniques, including elemental analysis, infrared spectroscopy, APCI/MS, and XPS. Particularly, two relatively new instrumental techniques of APCI/MS and XPS were used to characterize the composition of polar components in the oil sample. (11) Wang, H.; et al. Acta Petr. Sin., Petr. Process. Sect. 2003, 19, 72-77. (12) Zhu, Y.; et al. Acta Petr. Sin., Petr. Process. Sect. 2002, 18, 1922.
10.1021/ef049830e CCC: $30.25 © 2005 American Chemical Society Published on Web 01/26/2005
626
Energy & Fuels, Vol. 19, No. 2, 2005
Han et al.
Table 1. Physical and Chemical Properties of Rubber Oil charcteristics appearance, 15 °C density viscosity, 40 °C viscosity, 100 °C flash point pour point neutralization sulfur, µg/g nitrogen, µg/g color, saybolt aniline point refractive index, 20 °C viscosity gravity constant UV absorption 260 nm molecular mass boil range hydrocarbon type anal. CN CP CA compositional analysis clay gel, % mass saturates aromatics polar components
unit
test method
ASTM D4176 kg/dm3 ASTM D4052 mm2/s ASTM D4052 mm2/s ASTM D4052 °C ASTM D93 °C ASTM D97 KOH/mg ASTM D974 wt% ASTM D2622 wt% ASTM D156 °C ASTM D611 ASTM D1747 ASTM D2501 L/g‚cm ASTM D2008 ASTM D2502 °C ASTM D2140
typical data clear bright 895.7 130.6 9.666 218 -27 0.01
