Base Stock Properties

Processing steps which act by chemical separation The undesirable chemical compounds (e.g., polyaromatics) are removed using solvent-based separation methods (solvent refining). The by-products (extracts) represent a yield loss in producing the base stock. The base stock properties are determined by molecules originally in the crude, since molecules in the final base stock are unchanged from those in the feed or... 

A number of papers have looked at the development of relationships between base stock composition as measured by NMR and either physi-cal/chemical properties or their performance.22 27 Most of this work has been focused on group II and III base stocks, with less or little attention paid to solvent extracted ones. These have all relied on various techniques to simplify the spectra and the assignments of peaks and make peak integration more reliable. These have many acronyms,23 for example, GASPE (gates spin echo), PCSE (proton coupled spin echo), INEPT (insensitive nuclei enhancement by polarization transfer), DEPT (distortionless enhancement by polarization), QUAT (quaternary-only carbon spectra), 2D COSY (two-dimensional homo-nuclear spectroscopy), and HETCOR (heteronuclear shift correlated spectroscopy)]. Table 4.10 provides an example of some of the chemical shift data generated26 and employed in this type of work, and Adhvaryu et al.25 were able to develop the correlations between base stock properties and carbon types in Table 4.11, whose main features correspond to intuition (e.g., the values of API and aniline points are both decreased by aromatic carbon and increased by the... 

Equations Developed by Adhvaryu et al. for the of Base Stocks Property Prediction Repeatability Error of of Standard ... 

Provides a chemical composition background to base stock properties including viscosity and its temperature dependence, pour point, and oxidation stability... 

Table 2. Lubricant base stock property comparison C30-C42 hydrocarbons made from different...

Uses Solubilizer for fat-sol. vitamins, dill oil emulsifier for edible shortenings and oils, whipped toppings syn. flavoring agent In food Features Veg. source base stock Properties Solid HLB 15.0 100% cone. 

Each lubricating oil is composed from a main base stock, into which additives are mixed to give the lubricant the properties required for a given application. 

Table 4. Advantages and Limiting Properties of Synthetic Base Stocks ...

Vegetable and seed oils as well as some synthetic base stocks present a new class of biodegradable base stocks. These fluids (10) have excellent biodegradation properties as measured by criteria developed by the Environmental Protection Agency (EPA) or Organization of Economic Cooperation and Development (OECD). OECD 301 and EPA 560/6-82-003 measure the biodegradation of lubricants. These tests were developed to measure the degradation of oil, especially two-cycle ok, on waterways. Aquatic toxicity criteria toward fish is also found to be acceptable for this class of fluids as measured by EPA 560/6-82-002 and OECD 203 1-12. 

Although p oly (a-olefin) s (PAO) and esters are the prominent synthetic base stocks for automotive appfications, combinations of the two are becoming the choice in offering a balance of properties such as additive solubility, sludge control, and elastomer compatibility (34). 

If asphalts having properties in the area above the blowing curve are desired, the producer may resort to the use of oxidation catalysts, which have been the subject of extensive study in recent years (7,12,19, 36, 56, 77,118). The only catalysts known to be in large scale use are ferric chloride and phosphorus pentoxide (36, 45). Table II illustrates that asphalts of the same ring and ball softening point oxidized in the presence of these catalysts have markedly higher 77° and 32° penetrations than another prepared from the same base stock in the absence of catalyst. 

The crown-ether compounds as boundary lubricants and antioxidation additives. On the sliding surface, bromobenzo-15-crown-5 coordinates with ferrous ions and forms a strong reaction layer which protects the underlying metal surface. In the base stock solution, the crown ring can capture the metal ions which catalyze the oxidation of oil formulation (Brois and Gutierrez, 1987, 1989, 1992 and 1994 Le Suer and Norman, 1965 and 1966 Moreton, 1998). Bromobenzo-15-crown has excellent antiwear, antifriction and antioxidation properties, better than the ZDDP tested. 

Diester synthetic base stock lubricants formulated with 2-ethylhexanol (e.g., di-2-ethylhexyl adipate) provide excellent low temperature starting properties in automotive crank case applications and are also employed as lubricants for industrial machinery such as compressors and turbines. 

It is the complex relationship between the yield of base stock, its VI and its cold flow properties (pour point and/or cloud point) that leads to the differentiation and optimization of selective dewaxing catalysts and processes, where shape selective catalysis is of critical importance. For example, Figure 8.10 shows the advantages of MSDW-2 over earlier technologies such as solvent dewaxing and MSDW-1 (25). 

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