Oxidation stability, separators

In another example of this technique, D. E. Cranton,36 at Imperial Oil, as part of a study on base stock oxidation stability, separated a midcontinent 150N solvent refined oil by thermal analysis and the ten fractions obtained were then further separated into saturates and aromatics by silica gel chromatography. Mass spectral analyses (Tables 3.11 and 3.12) show the results of the separation obtained in... 

Lube oil extraction plants often use phenol as solvent. Phenol is used because of its solvent power with a wide range of feed stocks and its ease of recovery. Phenol preferentially dissolves aromatic-type hydrocarbons from the feed stock and improves its oxidation stability and to some extent its color. Phenol extraction can be used over the entire viscosity range of lube distillates and deasphalted oils. The phenol solvent extraction separation is primarily by molecular type or composition. In order to accomplish a separation by solvent extraction, it is necessary that two liquid phases be present. In phenol solvent extraction of lubricating oils these two phases are an oil-rich phase and a phenol-rich phase. Tne oil-rich phase or raffinate solution consists of the "treated" oil from which undesirable naphthenic and aromatic components have been removed plus some dissolved phenol. The phenol-rich phase or extract solution consists mainly of the bulk of the phenol plus the undesirable components removed from the oil feed. The oil materials remaining... 

Steam-turbine lubricants Lubricants in steam turbines are not exposed to such arduous conditions as those in engines. The main requirement is for high oxidation stability. However, they may be exposed to aqueous condensate or, in the case of marine installations, to sea water contamination, so they have to be able to separate from water easily and to form a rustpreventing film on ferrous surfaces, and it is usual to employ rust inhibitors. The problem of tin oxide formation on white-metal bearings is associated with the presence of electrically conducting water in lubricants and can be over-come by keeping the lubricant dry . 

The choice of a suitable oil has special importance. Besides beneficial effects of the oil on the oxidative stability of the separator, other consequences have to be considered. From the chemical mixture of which an oil naturally consists, polar substances may migrate into the electrolyte. Being of lower density than the electrolyte, they accumulate on its surface and may interfere for instance with the proper float function of automatic water refilling systems. Some oils which fully meet both of the above requirements have been identified, i.e., they provide sufficient oxidation stability without generating black deposits [53],... 

Spinel oxides are important industrial catalysts, possessing good thermal and chemical stability and an ability to maintain catalytic activity at high temperatures. The study reported here is concerned with the properties ofZn(II)-Cr(III) spinel oxides prepared from a carbonate containing LDH precursor. For this study the spinel oxide was separated, by treatment with dilute mineral acid, from the oxide mixture (ZnO and ZnC O, ) obtained by the thermal decomposition of LDH. For comparison, Zn(II)-Cr(lII) spinel oxides were also prepared by more standard synthesis methods. Structural and textural properties were evaluated, using PXRD, TG/MS, FT-IR and N2 adsorption. 

Segmented polyimide-polydimethylsiloxane copolymers have been successfully synthesized both in laboratory and industrial quantities to produce multiphase siloxane-modified polyimides. The siloxane detracts somewhat from the otherwise excellent thermo oxidative stability of the polyimide, but it does produce a number of important properties. These include multiphase behavior, improved adhesion to many substrates, improvements in fire resistance and enhanced gas and liquid separation membranes, where one wishes not only to maximize the contribution of the siloxane to permeability, but also to utilize the imide to re-... 

Tricresylphosphate from receptacle 9 enters flusher 11, which is a cylindrical apparatus with an agitator. First of all, tricresylphosphate is washed with 3% sodium hydroxide to neutralise residual hydrochloric acid and separate cresol (the allowable cresol content in tricresylphosphate is 0.6 g/1). It is also recommended to treat the product with diluted solution of potassium permanganate to improve the colour and oxidation stability of tricresylphosphate. 

Is the Iodine Value found in EN 14214 based on science It is certainly not so in an absolute way, but some relation cannot be denied. Frankel (2005) for example clearly states that oxidation stability is a function of two things the number of double bounds, and their position towards one another in the fatty acid. Oleic acid with one double bound oxidizes 40 times slower than linoleic acid with two double bounds, and one bis-allylic position in-between both. Linolenic acid with three double bounds separated with two bis-allylic positions oxidizes only 2.5 times faster than linoleic acid. Oxidation is a radical driven reaction, and the bis-allylic positions are a much more favorable point of attack than the allylic positions next to the double bound. 

In the fractionation process, the minor components of the original oil become concentrated in the separated fractions. This concentration has a considerable effect on the oxidative stability of the individual fractions. Relative to the starting oil, the liquid or soft fraction is enriched in tocopherols and depleted of trace metals. The reverse occurs with the hard or stearine fraction, which becomes appreciably more susceptible to oxidation despite its lower content of unsaturates. The stearine fraction is also the recipient of other impurities remaining in the oil after rehning and bleaching, such as phosphatides and soap. 

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