24th International Colloquium Tribology - January 2024 255 High Quality Sustainable Base Oils from Plastic Waste and Biomass Matias de Tezanos 1* , Boris Zhmud 2 1 KATA Circular Pte Ltd, Singapore, Singapore 2 Tribonex AB, Uppsala, Sweden * Corresponding author: mdt@kata.com Plastic pollution is a serious and constantly growing environmental threat. In 2022, global annual plastics production has reached 460 million tons. Estimated global leakage of plastic waste to the environment was 22 million tons in 2019, and this estimate is projected to double by 2060. The use of plastics in agri-food systems and food value chains is particularly widespread. Polyethylene and polypropylene are two common polymers used in agriculture for multiple applications. These polymers can be readily upcycled into value-added products. Unfortunately, despite the fact that plastic waste can be used as raw material in chemical industry, there is a lack of systematic collection and sustainable management. Figure 1: Estimated quantities of agricultural plastics used per hectare of land [1] Pyrolysis is one common technique used to convert a wide range of plastics into a complex mixture of alkanes, alkenes, alkynes, and aromatics that can be further used in traditional petrochemical processes. Another possibility is catalytic hydrogenolysis that uses hydrogen to cleave carbon-carbon bonds producing predominantly alkanes. Unfortunately, so far, these processes have not been economically competitive with traditional crude oil processing due to relatively low crude oil prices. However, the situation is gradually changing thanks to the introduction of carbon credits. Figure 2: Upcycling of waste plastic [2] The Fischer-Tropsch (FT) process is the basis for nearly all technological processes dealing with conversion of natural gas and coal to more valuable liquid hydrocarbons. In the past decades, lubricating oils derived from FT waxes started to gain interest. Unfortunately, the availability of FT waxes is rather limited to cover market needs. Another serious concern is the heavy carbon footprint of such processes. In such a situation, waste plastic avail itself as a perfect substitute for FT and slack waxes from petroleum refining, leading the way to a truly sustainable process with a greatly reduced carbon footprint and environmental impact: instead of dumping waste plastic to landfills, we can convert it into value-added products. KATA has developed an innovative way to chemically upcycle plastic waste originating from agriculture. In the present communication, properties and applications of novel sustainable base oils and additives produced from biomass and plastic waste are presented, with a focus on common physicochemical properties, property blending relationships and tribological performance. KATA technology allows one to convert PE and PP agricultural waste plastic into high quality sustainable fuels, solvents and base oils. Originating from a non-petroleum feedstock, KATA oils contain no aromatic and naphthenic molecules, being 100% composed of iso-paraffins. This leads to improved low temperature flow properties and oxidation stability. Compared to traditional mineral oils, KATA oils have more narrow molecular weights and boiling points distribution, as distillation curves indicate (Figure 3). Figure 3: Distillation curves for conventional mineral base oil and synthetic base oil produced from plastic. The yield of value-added products is close to 80%. The actual partitioning of individual products depends on process conditions. Thus, one can prioritize the production of fuel, the production of wax, etc. Approximate outputs of different product streams are shown in Figure 4. 256 24th International Colloquium Tribology - January 2024 High Quality Sustainable Base Oils from Plastic Waste and Biomass Figure 4: Approximate outputs of different products produced by plastic waste upcycling Thus, Table 1 presents typical properties of sustainable white oil, SBS 100, produced from waste plastic. This oil has been benchmarked against traditional API Group III/ III+ and Group IV base oils in a number of finished lubricants and demonstrated comparable, and in some cases, superior, performance. Table 1: Typical properties of SBS100 white oil Typical Properties Method Unit SBS100 Specific gravity @ 15-°C ASTM D1298 g/ cm 3 0.832 Flash Point ASTM D92 °C 200 Pour Point ASTM D97 °C -38-°C Kin. viscosity @ 40-°C ASTM D445 cSt 16.1 Kin. viscosity @ 100-°C ASTM D445 cSt 3.8 Viscosity Index ASTM D2270 - 130 Noack DIN 51581 % 15 Color ASTM D1500 - <-Lo.5 Sulfur ASTM D2622 ppm <-10 Further, Table 2 shows the properties of a different product an ester derived from castor oil. This product has been evaluated as co-emulsifier and lubricity improver in cutting oils. Table 2: Typical properties of ricinoleic ester Property Method Unit Value Kin. viscosity @ 100-°C ASTM D445 cSt 3.5 Kin. viscosity @ 40-°C ASTM D445 cSt 17.6 Viscosity index ASTM D2270 - 56 Specific gravity @ 20-°C ASTM D4052 g/ cm 3 0.92 Pour point ASTM D6892 °C -24 Flash point ASTM D92 °C 208 KATA operations rely upon a closed loop supply chain, paving the way to a truly sustainable manufacturing ecosystem. Waste plastic is collected from local farmers, converted to value-added products, such as agricultural lubricants, fuels and crop protection oils, which are sold back to the farmers. By co-processing castor oil with rapeseed oil, organic friction modifiers were produced demonstrating outstanding friction-reducing properties when used together with API Group IV base oils. Figures 5(a) and 5(b) show the MTM test data for various organic friction modifiers at 0.5% treat level in PAO4 base oil. “Base” denotes the pure base oil and “XFM” denotes the novel cross-linked polymeric friction modifier. (a) (b) Figure 5: MTM test data comparing the tribological efficiency of various friction modifiers in fresh (2 h at 100- o C) formulations and aged formulations (8 h at 100- o C + 8 h at 130- o C). The XFM polymeric organic friction modifier demonstrates top-of-the-class efficiency and superior effect retention compared to other commercial OFM systems. This makes it attractive for use in industrial and transportation lubricants as a replacement for inorganic friction modifiers [3]. References [1] FAO. 2021. Assessment of agricultural plastics and their sustainability. A call for action. Rome. https: / / doi. org/ 10.4060/ cb7856en [2] R. Hackler, K. Vyavhare, R. Kennedy, et al. Synthetic Lubricants Derived from Plastic Waste and their Tribological Performance, ChemSusChem. 10.1002/ cssc.202100912. [3] B. Zhmud, N. Stawniak, S. Ressel, Metalworking Fluids and Industrial Lubricants Based on Novel Rapeseed Oil Varieties, Lube 174 (2023) 9.