Síntese enzimática de biolubrificantes a partir de óleos vegetais ácidos e/ou resíduos industriais do processamento de óleos vegetais

Abstract

Given the current scenario of energy transition, biolubricants are an interesting alternative to replace lubricating oils from fossil sources, which are the most used in the market to reduce friction effects between surfaces, among other several applications Biolubricants are composed of fatty acid esters that can be derived from biomass, such as vegetable oils, from transesterification reactions of oils or esterification of fatty acids with long linear and/or branched-chain alcohols. This work aimed at evaluating the enzymatic production of fatty acid esters for biolubricant bases by esterification of commercial fatty acids and isoamyl alcohol using as a biocatalyst a liquid lipase formulation from Novozymes A/S, Eversa Transform®, which was specially formulated to product biodiesel from lipid material with high free acidity. From experimental data of ester yield or substrate conversion over time, as well as data reported in the literature for the synthesis of esters from fatty acids and DDOS (distillate from the deodorization of soybean oil), kinetic modeling were made to determine which models best fit this type of reaction (classic Michaelis-Mentem, Michaelis-Menten with inhibition, Ping Pong Bi-Bi, etc.), thus allowing the obtaining of kinetic (such as Vmax, Km, KI) and thermodynamic (enthalpy and activation energy) parameters. Also, the specificity of the enzyme for different fatty acids was determined, evaluating its affinity in relation to chain size and the presence of unsaturations, showing best results regarding to fatty acids of saturated medium-to-long chains, such as stearic acid. Regarding the solvent used, heptane proved to be more adequate. Conversion profiles over time using lauric acid (C12:0) and coconut oil (mostly composed of ca. 70% of medium-chain saturated fatty acids – C12:0-C16:0) were also evaluated. For lauric acid, a higher conversion was observed in the interval of 12 to 24 h, reaching a maximum conversion of 45%. For coconut oil, the yield of isoamyl esters was evaluated, obtaining a yield lower than 3.5% at the end of 24 h of reaction.