Oligomers, olefinic, synthetic

Hydrocarbons. Synthesized hydrocarbons are the most popular of the synthetic base stocks. These are pure hydrocarbons (qv) and are manufactured from raw materials derived from cmde oil. Three types are used olefin oligomers, alkylated aromatics, and polybutenes. Other types, such as cycloahphatics, are also used in small volumes in specialized apphcations. 

The transportation fuels produced and marketed (Table 18.9)40 met the South African fuel specifications of that time and included some coal-derived liquids (not shown in Figure 18.5). Although the refinery originally produced no jet fuel, it was demonstrated that the hydrogenated kerosene range oligomers from olefin oligomerization over a solid phosphoric acid catalyst met the requirements for jet fuel.38 (Semisynthetic jet fuel was approved in 1999 and fully synthetic jet fuel was approved in 2008 DEFSTAN 91-91/Issue 6). 

Hydrocarboxylation of the Ce-Cs a-olefins with cobaltcarbonyl/pyridine catalysts at 200 °C and 20 MPa gives predominantly the linear carboxylic acids. The acids and their esters are used as additives for lubricants. The Ce-Cio a-olefins are hydroformylated to odd-numbered linear primary alcohols, which are converted to polyvinylchloride (PVC) plasticizers with phthalic anhydride. Oligomerization of (preferably) 1 -decene, applying BF3 catalysts, gives oligomers used as synthetic lubricants known as poly-a-olefins (PAO) or synthetic hydrocarbons (SHC) [11, 12]. The C10-C12 a-olefins can be epoxidized by peracids this opens up a route to bifunctional derivatives or ethoxylates as nonionic surfactants [13]. 

Developments in PAO technology include using acidic aluminosilicate shape-selective catalysts. Use of chromium on silica gel catalyst and a shape-selective metallosilicate produced olefin oligomers as suitable intermediates for reaction with an enophile to produce polar synthetic base stocks [33],... 

The choice of synthetic hydrocarbons for lubricant use is not restricted to olefin oligomers. It is entirely credible that among the thousands of hydrocarbons of various structures will be found many whose properties make them worthy of attention as possible lubricants. For example, Wilgus, Ettling and Pino [1] investigated the potential usefulness as high-temperature, radiation-resistant hydraulic fluids of a series of diarylalkanes of the general type... 

Despite its unique effectiveness as a cocatalyst, MAO still remains a black box . Depending on the nature of the hydrated salt (the H2O source) used for the MAO synthesis and the exact MAO synthetic reaction conditions, MAO-activated metallocenes may exhibit widely differing activities in olefin polymerization. The MAO structure can hardly be elucidated directly because of the multiple equilibria present in MAO solutions, and residual trimethylaluminum in MAO solutions appears to participate in equilibria that interconvert various MAO oligomers. There are two types of TMA present in typical MAO solutions free TMA and associated TMA (eq 3). 

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