Síntese e caracterização de biolubrificantes obtidos através de modificações químicas no óleo de soja refinado

Abstract

Estimates of the lack of petroleum in the near future have motivated research to investigated fuels and refined products to petroleum alternative. Synthesizing various vegetable oils lubricants, to reduce the contamination caused by the use of conventional lubricants. The objective of this work is to carry out chemical modification of soybean oil by transesterification reaction followed by epoxidation, alkoxy- hydroxylation, di-hydroxylation and acetylation to improve the characteristics of these oil lubricants. Transesterification were performed using methanol at a molar ratio oil/methanol 1:6 and 0.7% catalyst. The epoxides were produced using commercial 15% peracetic acid, reaching oxirane oxygen content of 13.2%. The alkoxy-hydroxylation were catalyzed by Fe2(SO4)3 and p-toluenesulfonic acid (APTS) using different alcohols (methanol, ethanol and 1-propanol) and water. Fe2(SO4)3 was the catalyst more efficient. The best conditions to alkoxy-hydroxylation reactions were with 3% ratio of catalyst to oil/ethanol 1:3, and 5% of catalyst relative to oil/water, In these conditions, the oxirane oxygen levels were reduced to zero. Acetylation was carried out using acetic anhydride in a molar ratio oil/reagent 1:2.5. The reaction of alkoxy-hydroxylation caused a significant increase in the kinematic viscosity of 34.18 mm².s-1 ; 54.82 mm².s-1 ; 46.34 mm².s-1 and 100.02 mm².s-¹ for o EMOSRMH, EMOSREH, EMOSRPH and the EMOSRDH respectively. These results show that the viscosities of alkoxy-hydroxy and di-hydroxylated lubricants are superior to refined soybean oil. With the acetylation of alkoxy-hydroxides and di-hydroxylated lubricants, kinematic viscosity values were 46.22 mm².s-1; 42.22 mm².s-1; 28.44 mm².s-¹ and 49.30 mm².s-1 for EMOSRMA, EMOSREA, EMOSRPA and MOSRMDA, respectively. The increase in viscosity for the alkoxy-hydroxylated lubricants occurs in the following order: DH, EMH, EEH and EPH. For acetylated order is EMA, EEA, EPA and DHA. These results indicate that the size of the ester chain branching alters the viscosity. All products were characterized by Physicochemical analyzes and by 1H and 13C NMR spectra. It can be concluded that the method presented here enables obtaining potential biodegradable lubricants.