Chemical Route for the Synthesis of Diesel Fuel via Decarboxylation of Vegetable Oils

Description

/ 6 Chemical Route for the Synthesis of Diesel Fuel via Decarboxylation of Vegetable Oils Utility model field

[001] The utility model describes a chemical route for obtaining a fuel with the same chemical composition as fossil-derived diesel using vegetable oils as a substrate. The chemical synthesis route for this diesel fuel involves the initial saponification of the fatty acids present in the vegetable oil and subsequent decarboxylation of the fatty acid salts, producing a mixture of alkanes. As a model of this utility model, a sample of the fuel was produced which, after analysis, contains alkanes with 18-carbon chains in its composition. Fundamentals of the utility model

[002] Currently, there are two forms of diesel developed without using fossil fuels as raw materials, aiming for sustainability. One is biodiesel, which is produced from vegetable oil and has a 100% sustainable origin, but has a very different chemical structure from fossil diesel, making it impossible to completely replace it with biodiesel. The second form of sustainable diesel is called green diesel. Green diesel, or HVO (Hydrotreated Vegetable Oil) diesel, also uses renewable sources such as vegetable oil and produces diesel with a chemical structure identical to fossil diesel. The disadvantage of green diesel is the need for hydrogen gas (of fossil origin) in its production process, in addition to the high production costs.

[003] The chemical route for biodiesel production mainly involves the transesterification of vegetable oils or animal fats. In this process, the oils or fats react with an alcohol (usually methanol or ethanol) in the presence of a catalyst, which can be acidic, alkaline, or enzymatic, to form methyl or ethyl esters of fatty acids (biodiesel) and glycerol as a byproduct (RAMOS, 2016). The advantages of biodiesel lie in its sustainability as it is derived from natural sources. Petition 870260054542, dated 05 / 06 / 2026, page 5 / 12 / 6 renewables, which contributes to reducing dependence on fossil fuels. Its disadvantages are the high production cost compared to fossil fuels and performance and stability problems compared to petroleum diesel.

[004] Green diesel, also known as HVO (Hydrotreated Vegetable Oil), is a type of biofuel produced from vegetable oils or animal fats, but through a different process than conventional biodiesel. The HVO production process involves treating vegetable oils or fats with hydrogen gas at high temperatures in the presence of a catalyst. This process removes oxygen from triglycerides and forms paraffinic hydrocarbons, which are chemically very similar to petroleum diesel (MILANEZ, 2022). The advantages of using green diesel are the high quality of the fuel due to its great chemical similarity to fossil-based diesel, combined with sustainability because it is derived from renewable sources. Its disadvantages are the high production cost compared to conventional biodiesel and its dependence on the use of hydrogen gas, which is obtained from fossil sources. Brief description of the drawings and formulas.

[005] The chemical route used to produce diesel uses the Dumas decarboxylation reaction of fatty acid salts resulting from the saponification reaction of triglycerides present in soybean oil to produce a combination of alkanes that can be used as fuel (CARNEIRO, 2020).

[006] Dumas decarboxylation is a chemical reaction where initially the acid group of an organic compound is neutralized, producing its corresponding salt. Then the compound is heated with soda lime where the decarboxylation of the salt occurs, resulting in an alkane and sodium carbonate (LOPES, 1998). Formula 1 illustrates in detail the Dumas decarboxylation process. Petition 870260054542, dated 05 / 06 / 2026, page 6 / 12 3 / 6 Formula 2 provides a detailed illustration of the chemical synthesis process for diesel fuel. Acetic Acid Sodium Acetate Hydroxide0 Sodium + H2O Water O u XO“ Na+ Sodium Acetate + NaOH Sodium Hydroxide H I H—C—H + Na2CO3 I H Methane Sodium Carbonate Formula 1

[007] The chemical synthesis route for diesel begins with the saponification reaction of soybean oil triglycerides using sodium hydroxide. This reaction produces the corresponding fatty acid salt and glycerol. The glycerol is then separated and removed from the mixture. The fatty acid salt is then mixed with sodium hydroxide and calcium oxide and heated to 50°C. At this point, the Dumas decarboxylation reaction occurs, producing the alkane corresponding to the fatty acid salt and sodium carbonate. The alkane is then separated from the sodium carbonate and purified. Cs1H9806+ 3NaOH - 3C16H3102Na + C3Ha03 Triglyceride of Palmitic acid Sodium Hydroxide Sodium Palmitate Glycerol 3Cl6H3lO2Na + 3NaOH → 3ClaH32 Sodium Palmitate Sodium Hydroxide Pentad ecano + 3Na2CO3 Sodium Carbonate Formula 2 Petition 870260054542, dated 05 / 06 / 2026, page 7 / 12 / 6

[008] An example of the chemical mechanism for obtaining diesel proposed in this patent is the conversion of linoleic acid, the main fatty acid constituent of soybean oil, into its alkene. The chemical route begins with the saponification reaction of sodium hydroxide [1] with linoleic acid triglyceride [2]. This reaction produces glycerol [3] and the sodium salt of linoleic acid [4]. The linoleic acid salt [4] is then mixed with sodium hydroxide [1] and heated to 50°C. At this point, the Dumas decarboxylation reaction of the linoleic acid salt [4] occurs, producing the alkene corresponding to the linoleic acid salt [6] and sodium carbonate [5]. The alkene is separated from the sodium carbonate and purified.

[009] As a way of representing the example and the route of chemistry, we have prepared 4 Figures which are included in the Drawing. Figure 1 illustrates a triglyceride molecule (glycerol esterified with three long-chain saturated fatty acids) next to sodium hydroxide (NaOH), representing the mixture for the saponification reaction (oil / fat + strong base). Figure 2 shows three soap molecules, that is, the sodium salts of long-chain fatty acids (R-COO” Na+) alongside sodium hydroxide (NaOH), representing the mixture for the Dumas reaction (thermal decarboxylation of fatty acid salts). Figure 3 details a set consisting of sodium carbonate (Na2CO3) and a long-chain saturated hydrocarbon (alkane, RH), products resulting from the thermal decarboxylation of fatty acid salts (Dumas). Figure 4 highlights a glycerin / glycerol molecule accompanied again by the three soap molecules (sodium salts of long-chain fatty acids), representing the mixture resulting from the saponification reaction. Description of the utility model Petition 870260054542, dated 05 / 06 / 2026, page 8 / 12 / 6

[0010] In order to confirm the chemical viability of the diesel production synthesis route via Dumas decarboxylation, a small-scale synthesis was carried out on a laboratory bench. A beaker containing 200 ml of soybean oil was heated to 50°C on a hot plate. The beaker was then removed from the heat and 25.387 g of sodium hydroxide was added. This mixture was allowed to react for one hour. After this hour, the mixture was heated again and water and sodium chloride were added. The mixture was then transferred to a separatory funnel where it was allowed to settle for 24 hours. After this period, a layer containing glycerol, sodium chloride, and non-reactive sodium hydroxide was formed, along with another layer containing the fatty acid salts of the soybean oil. This last layer was collected and transferred to another 500ml beaker where it was mixed with soda lime (25.387g of sodium hydroxide and 71.17g of calcium oxide) and heated to 50°C.The reaction was allowed to proceed for 30 minutes. The resulting mixture was removed from the heat, transferred to a separatory funnel, and left to settle for 24 hours. After this period, two layers formed again, one possibly containing alkanes and the other containing sodium carbonate, sodium hydroxide, calcium oxide, glycerol, and non-reactive impurities. The layers were separated by decantation, and the layer containing the alkanes was collected and sent for chromatographic characterization. This layer showed that 87% of its volume was composed of the hydrocarbon octadecane. Bibliographic references CARNEIRO JÚNIOR, AR; Lima, IDR; Lima, MOB de; Araújo, MA dos S. A sustainable activity: soap production from fat generated in the production process of a dairy. Ciências Exatas e Tecnológicas, Alagoas, v. 6, n. 2, p. 142-155, Oct. 2020. Available at: periodicos.set.edu.br. LOPES, VM; Rzyski, BM Immobilization of solutions containing citric acid in Portland cement. Institute of Energy and Nuclear Research - IPEN-CNEN / SP, P.O. Box 11049, 05422-970, 1998, São Paulo, Brazil. Petition 870260054542, dated 05 / 06 / 2026, page 9 / 12 / 6 MILANEZ, AY; Maia, GB da S.; Guimarães, DD; Ferreira, CLA. Biodiesel and green diesel in Brazil: recent overview and perspectives. BNDES Sept., Rio de Janeiro, v. 28, n. 56, p. 41-71, Sept. 2022. RAMOS, LP; Kothe, V.; César-Oliveira, MAF; Muniz-Wypych, AS; Nakagaki, S.; Krieger, N.; Wypych, F.; Cordeiro, CS Biodiesel: Raw Materials, Production Technologies and Fuel Properties. Rev. Virtual Quim., 2017, 9 (1), 317-369. Web publication date: December 9, 2016. Petition 870260054542, dated 05 / 06 / 2026, page 10 / 12

Claims

CLAIMS [001] FUEL DIESEL characterized by having a chemical synthesis route of diesel with chemical characteristics of fossil diesel via Dumas decarboxylation of vegetable oils. [002] FUEL DIESEL, characterized by having a chemical synthesis route of diesel with chemical characteristics of fossil diesel via decarboxylation of animal fats. Petition 870250108351, dated 11 / 26 / 2025, page 6 / 16

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