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Abstract: The lubricants of the future have to be more environmentally adapted, have a higher level of performance. Synthesis esters (SEs) which can be used as raw materials for biodegradable lubricant base oils are increasing in popularity due to superior technical properties. Direct esterification of trimethylolpropane (TMP) with fatty acid in a solvent free system, by immobilized lipase from Candida sp. 99–125 was studied. Investigations of important factors were carried out involving temperature, time, enzyme amount, substrates molar ratio and water content. For 2g caprylic acid, under the optimal conditions, with 0.4g immobilized lipase, at substrates molar ratio 1:10 (TMP to acid), temperature 40°C and water content controlled under 0.8% (w/w), the total conversion of fatty acid with TMP reached up to 96% and the formation of trisubstituted TMP esters reached 93%. Water content controlled during esterification process was found to be critical for high yield of direct esterification. [Copyright &y& Elsevier]

Biolubricants produced by chemically modifying vegetable oils are promising to replace mineral-based lubricants. However, the performances of biolubricants synthesized through traditional chemical modification routes, such as transesterification/esterification, epoxidation with further ring opening, and estolide formation, cannot satisfy the demands of extreme conditions. Meanwhile, complicated multi-step reactions cause expensive costs, which hinders their large-scale application. In this study, pelargonic acid (PA) derived from the cleavage of oleic acid was esterified with trimethylolpropane (TMP) to produce branched-chain esters (tri-TMP esters) catalyzed by the lipase (Candida sp. 99–125), focusing on batch stability of the lipase, thermal-oxidation stability and lubrication performance of the product. The lipase maintained high activity for 4 continuous batches in 5 L enzyme reactor with the conversion of PA > 96% and the accumulation of tri-TMP esters > 84% in each batch. The obtained tri-TMP esters had a pour point of − 56 °C, a viscosity index of 137, and a flash point of 276 °C. Anti-oxidation stability test and thermogravimetric behaviors showed that the biolubricant had favorable thermal-oxidative stability. Friction tests verified that the product displayed excellent lubrication performance with a minimum coefficient of friction (COF) of 0.099 and an average wear spot diameter (WSD) of 221.5 µm. The green and high-selective synthetic pathway fills the defect of existing routes for the preparation of biolubricants from chemically modified vegetable oils. [Display omitted] • Lipase-catalyzed synthesis of branched-chain esters based on PA and TMP was proposed. • The lipase maintained high activity for 4 continuous batches. • The tri-TMP esters has superior low-temperature performance and thermal-oxidative stability. • This biolubricant displayed excellent lubrication performance in HFRR tests. [ABSTRACT FROM AUTHOR]

In this work, the acetone-butanol-ethanol (ABE) fermentation was upgraded in order to improve its economy. Fed-batch fermentation was integrated with two-stage gas stripping-pervaporation unit. The permeated ABE condensate was used as substrate for oleates production. Candida sp. 99–125 cells, being rich in lipase activity, were used as full-cell catalyst. Different ABE feeding strategies in the esterification process were compared. As results, 10.1%, 68.6% and 72.5% of butyl oleate were obtained in the one-step added scenario, the stepwise-added scenario, and the simultaneous fed-batch scenario, respectively. The novel hybrid process was energy-saving, environmentally friendly and profitable, showing promise in future industrialization. [ABSTRACT FROM AUTHOR]

In this work, phytosterol ester was synthesized using Yarrowia lipolytica lipase Ylip2 that had been immobilized on inorganic support in a solvent-free system and reacted in a computer-aided water activity controlled bioreactor. The immobilization of Ylip2 on celite led to a remarkable increase in the phytosterol conversion compared to that of free lipase. An investigation of the reaction conditions were oleic acid as the fatty acid variety, 10,000 U/g substrate, and a temperature of 50 °C for phytosterol ester synthesis. Controlling of the water activity at a set point was accomplished by the introduction of dry air through the reaction medium at a digital feedback controlled flow rate. For the esterification of phytosterol ester, a low (15%) water activity resulted in a considerable improvement in phytosterol conversion (91.1%) as well as a decreased reaction time (78 h). Furthermore, Ylip2 lipase immobilized on celite retained 90% esterification activity for the synthesis of phytosterol oleate after reused 8 cycles, while free lipase was only viable for 5 batches with 90% esterification activity remained. Finally, the phytosterol oleate space time yield increased from 1.65 g/L/h with free lipase to 2.53 g/L/h with immobilized lipase. These results illustrate that the immobilized Yarrowia lipolytica lipase Ylip2 in a water activity controlled reactor has great potential for the application in phytosterol esters synthesis. [ABSTRACT FROM AUTHOR]

Highlights: [•] Lipase was absorbed on surface hydrophobic modified silk fibers. [•] Immobilized lipase and feeding methods improve synthesis of tri-TMP esters. [•] Immobilized lipas showed increase esterification activity and decrease hydrolysis activity. [•] TMP-feeding methods kept a high molar ratio of fatty acid to TMP during process. [Copyright &y& Elsevier]