Relationship between Lubricating Basestock Composition and the Effects of Additives on Oxidation Stability

Hsu, Stephen M.; Ku, C. S.; Lin, Rong-Yan

doi:10.4271/821237

Cited by 15 publications

(5 citation statements)

References 8 publications

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“…In a similar manner to the ashless antioxidants, the response pattern of the ZnDTPs used in these fluids is strongly influenced by the degree of raffination of the base stock [82].…”

Section: Industrial Lubricantsmentioning

confidence: 98%

Oxidative Degradation and Stabilisation of Mineral Oil-Based Lubricants

Aguilar

Mazzamaro

Rasberger

2009

Chemistry and Technology of Lubricants

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Thermally induced hydrocarbon oxidation is a self-accelerating autoxidation process and is divided into 'low'-, 30-120 • C, and 'high'-, >120 • C, temperature phases. The first has four stages -induction of radical chain reactions, propagation, branching and then termination. Mechanisms of these processes are described and discussed. Differences in hydrocarbon reactivity are related to molecular structure. For hydrocarbon oxidation >120 • C, the first stage is the same as low-temperature oxidation but with reduced selectivity and increased reactivity; second, the oxidation phase becomes diffusion controlled as hydrocarbon viscosities increase from progressive polycondensation of higher molecular weight products, causing varnish and sludge formation. Base oil oxidation stabilities depend upon their derivation, whether solvent neutral, hydrocracked or synthetic, and their response to antioxidant treatment. Lubricant oxidation control focuses on radical scavengers and hydroperoxide decomposers and their synergistic mixtures.Engine oils increasingly use phenolic and aminic antioxidants as radical scavengers with organometallic complex antioxidants. Sterically hindered phenols substituted at 2-and 6-positions by t-butyl groups are particularly effective, reacting successively with peroxy radicals to form stable cyclohexadieneone peroxides. Secondary amines as either two aryl or phenyl and naphthyl groups are very effective at eliminating four peroxy radicals per molecule. They are more effective by a ratio of 4:2 than the sterically hindered phenols below 120 • C. At higher temperatures a catalytic cycle is suggested as an extended stabilisation mechanism. Transition metal ions with two valence states, Fe 2+/3+ , Cu 1+/2+ , etc. as trace quantities of metal soaps catalyse/retard autoxidation according to concentration and/or combination of metals. They catalyse or inhibit oxidation by complexing and decomposing hydroperoxides or can also oxidise peroxy radicals and reduce alkyl radicals to inert products. Organomolybdenum complexes such as molybdenum dialkyldithiocarbamates, MDTC, are increasingly used to stabilise engine lubricants particularly because of synergy with other antioxidants such as alkylated diphenylamines. 107 R.M. Mortier et al. (eds.), Chemistry and Technology of Lubricants, 3rd edn.,

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“…In a similar manner to the ashless antioxidants, the response pattern of the ZnDTPs used in these fluids is strongly influenced by the degree of raffination of the base stock [82].…”

Section: Industrial Lubricantsmentioning

confidence: 98%

Oxidative Degradation and Stabilisation of Mineral Oil-Based Lubricants

Aguilar

Mazzamaro

Rasberger

2009

Chemistry and Technology of Lubricants

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“…The high DBE species of HC (odd-electron) class are lost after oxidation; these are most likely structures with multiple aromatic cores. Multiring aromatics have been suggested to have an antioxidant effect due to formation of phenols; however, as their concentration in Group II base oils is low, they are not expected to have a significant effect on the oxidation. , In comparison, only a small number of species are lost from the HC [H] class, highlighting that HC and HC [H] classes represent chemically different species. A significant number of new HC [H] species are observed at an increased carbon number, likely generated by the reaction of alkyl radicals with hydrocarbon species.…”

Section: Discussionmentioning

confidence: 99%

Influence of Biodiesel on Base Oil Oxidation as Measured by FTICR Mass Spectrometry

Jones

Lozano

Huener³

et al. 2021

Energy Fuels

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Internal combustion engine lubricants are subject to thermo-oxidative degradation during use and must be designed to withstand oxidation in order to extend their useful life. Understanding the complex chemical process of thermo-oxidative degradation is essential to designing higher performing engine lubricants. In this study base oil samples composed of a Group II base oil, doped with three different levels of biodiesel (B0, B15, and B100), were subjected to benchtop oxidation testing of up to 168 h, which mimics the conditions experienced in an internal combustion engine. The resulting samples were analyzed by Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) for ultrahigh-resolution characterization to monitor oxidation as a function of time and biofuel content. Both negative-ion nanoelectrospray ionization and positive-ion atmospheric pressure photoionization were utilized. Most of the oxidation products were found to be polyoxygenated species containing 1–8 oxygen atoms, with the number of detected species increasing with oxidation time. Assessment of the maximum carbon number of protonated classes indicated the involvement of oligomerization reactions; additionally, modeling of mean double bond equivalents (DBE) for each protonated class suggests increasing carbonyl content for each particular class with increasing oxidation time. The oxidations of B15 and B100 doped samples were compared to that of B0. B15 samples were found to correspond closely to B0 samples, with a similar number of species detected. B100 samples showed a significant increase in number of species generated at 24–72 h relative to B0 and B15; however, a similar number of species were observed at 168 h for all samples, indicating a similar level of base oil oxidation at the final oxidation point. FTICR MS is shown to afford new insights into base oil oxidation as a function of time and biofuel content.

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“…44 Murray et al 45 concluded that the relationship between VI and oxidation performance of solvent-refined base oils held only for base oils from the same crude source and refining process. Robson 46 found that oxidation of lubricants formulated with hydrocracked base oils correlated inversely with aromatics content.…”

Section: Correlation Of Base Oil Composition and Lubricantmentioning

confidence: 99%

Lubricant Base Oils: Analysis and Characterization of

Shugarman¹

2000

Encyclopedia of Analytical Chemistry

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Lubricant base oils, or base stocks, are hydrocarbon lubricant components which are combined with performance additives to make finished industrial and automotive lubricants. A lubricant is a substance that reduces friction and wear between surfaces. Base oils typically comprise 80–99% of the finished lubricant. They are refined from selected crude oils, re‐refined from used oil, synthesized from specific organic compounds, or extracted from renewable resources, such as seed oils. Base oils formulated into finished lubricants help to reduce friction and wear between moving surfaces, remove heat, seal, cushion against shock loads, and remove abrasives and contaminants from the lubricated area. Base oil analysis and characterization is important for understanding how the physical and chemical properties of these materials relate to performance in finished lubricants. It is also essential for maintaining quality control (QC) over the manufacturing process, for quality assurance (QA) of the finished product, and for setting specifications between buyer and seller.

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Relationship between Lubricating Basestock Composition and the Effects of Additives on Oxidation Stability

Cited by 15 publications

References 8 publications

Oxidative Degradation and Stabilisation of Mineral Oil-Based Lubricants

Oxidative Degradation and Stabilisation of Mineral Oil-Based Lubricants

Influence of Biodiesel on Base Oil Oxidation as Measured by FTICR Mass Spectrometry

Lubricant Base Oils: Analysis and Characterization of

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