Abstract
Biodiesel plants are struggling to find value added applications for fatty acid methyl esters (FAME). One option for FAME valorization would be dibasic esters, which can be transesterified with 2-ethylhexyl (2EH) or other alcohols to produce lubricant basestocks and achieve the most widespread viscosity grades VG46 and VG32. Biocatalytic, metathesis and other synthetic pathways are available to produce dibasic esters. Using a ruthenium-based catalyst, methyl oleate was converted into monounsaturated dibasic ester by metathesis and reached VG22 after transesterification with 2EH in this investigation. Synthesized 2EH esters of other dibasic acids showed distinct viscometric trends. Their correlation implied that FAME from gondoic and erucic acids should result in VG32 and VG46 respectively, if converted into 2EH dibasic esters. Pour points demonstrated excellent low temperature fluidity and resistance to heat thinning when monounsaturation was retained. Oxidative stability properties remained acceptable, volatility was lower than that of VG46 mineral oils. Mixed alcohols, acids and esters can also be used for meeting VG specifications or achieving higher biobased contents. Currently petrochemical ester basestocks dominate in high performance hydraulic fluids (HF). However, fractionation of FAME into high-erucic/gondoic esters in biodiesel plants can produce a valuable biobased feedstock for large volume manufacture of HF and other lubricants.
Highlights
With petroleum prices uctuating around relatively low levels, biodiesel plants o en have operational difficulties
Synthesized 2EH esters of other dibasic acids showed distinct viscometric trends. Their correlation implied that fatty acid methyl esters (FAME) from gondoic and erucic acids should result in VG32 and VG46 respectively, if converted into 2EH dibasic esters
While saturated FAME are o en removed to improve low temperature uidity, other FAME of various chain lengths or double bond positions typically remain intermixed with the dominating methyl oleate and linoleate
Summary
Free FA as a raw material for various niche applications. Segregation of individual free FA is quite complicated, because they are not fractionated and distillation o en results in decarboxylation.[1]. In case of FAME, e.g. methyl oleate, selfmetathesis would lead to a monounsaturated difunctional methyl ester of a,u-C18:1-D9 dibasic acid.[12] Self-metathesis of FAME has already been attempted for several applications, but the HF basestock has only been pursued in patent literature.[13] Ole ns from FA metathesis had already been considered for motor oil basestocks.[14] the side products of selfmetathesis can be utilized for lubricants, just not as ester, but as hydrocarbon basestocks. In this investigation the experiments are limited to low temperature uidity, volatility and oxidative stability testing, i.e. the properties which are the most relevant to the basestock itself
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