New Qualities of Base Oils for Lubricants Resulting from Mixing Renewable Soybean Hydrocarbons with Conventional Group I, II, and III Base Oils

In line with the growing global demand for high-performance and more sustainable lubricants, this study investigated the production of renewable hydrocarbons by hydrodeoxygenation (HDO) of soybean oil, using the commercial NiMoS2/γ-Al2O3 catalyst (3% w/w). The objective was to obtain a partially renewable base oil by blending the HDO product with mineral base oils, aiming for its application in the formulation of biolubricants. The soybean oil was characterized by gas chromatography (GC-FID) and the catalyst by X-ray fluorescence and N2 adsorption/desorption. The HDO reactions were carried out in a batch reactor (350 °C, 70 bar H2, 800 rpm, 5 h), resulting in a conversion greater than 99% and a selectivity of approximately 91% for hydrocarbons within the adopted base oil range (C15 - C22). The renewable product ─RH─, composed mainly of C17 and C18 n-alkanes, displayed limitations for direct use as a base oil, mainly due to its low viscosity (3.96 mm2/s at 40 °C) and flash point (67 °C), as well as its high pour point (21 °C). To overcome these limitations, the RH II blend was formulated (25% RH and 75% Group II base oil), characterized according to ASTM standards, and compared with mineral base oils from Groups I, II, and III. The formulation satisfied important lubrication properties, such as high viscosity index (VI = 122), high flash point (176 °C), and elevated thermo-oxidative stability. Due to its VI, saturated content (99.3%), and absence of sulfur, RH II was classified as a Group III base oil according to ANP and API/ATIEL standards. Thus, the incorporation of 25% renewable hydrocarbons upgraded the Group II mineral oil to the high-performance category of Group III, highlighting the potential of soybean oil HDO to enhance the performance of mineral base oils and promote the production of more sustainable lubricants.