SYNERGICALLY INTEGRATED PRE-PROCESSES FOR OBTAINING BIOFUELS

Description

PRIOR RELATED APPLICATIONS

The present application claims priority to Brazilian Application BR 1020240024729, filed on Feb. 6, 2024. The entire content of prior application is incorporated by reference herein.

This invention is located in the field of chemistry, specifically fuels, more specifically renewable fuels, precisely pre-processes integrated synergistically to produce biofuels, in particular biodiesel and biokerosene.

Hydrotreated vegetable oils (HVO) commonly referred to as renewable diesel and green diesel, or hydroprocessed esters and fatty acids (HEFA) are produced through the hydroprocessing of oils and fats. Hydroprocessing is a process of transforming lipids into hydrocarbons by using hydrogen to remove the oxygens present in triglycerides, fatty acids or esters. HVO/HEFA are straight chain paraffinic hydrocarbons free of aromatics, oxygen and sulfur and with high cetane content. Therefore, HVO can normally be used on all diesel engines. In addition, the use as aviation fuel (biojet) has been approved in several countries around the world, including Brazil. Both the production of green diesel and biokerosene occur in the presence of valuable metal-based catalysts in these processes. The service life of these catalysts varies dramatically according to the purity of the raw materials.

An in-depth analysis of the current technology reveals a gap when it comes to combining biofuel production processes in order to maximize yields for green diesel and biokerosene, enhance the value of co-products and increase the durability of catalysts, as can be seen in patent CA3056537, “Hydrodeoxygenation process of vegetable oils for obtaining green diesel”, filed by Mexicano Inst Petrol on Sep. 27, 2018, which refers to a hydrodeoxygenation process for transforming mainly vegetable oils or non-edible animal fats, but not exclusively, to produce green diesel. The process involves contacting vegetable oil or inedible or edible animal fat with a catalyst synthesized from a mixture of transition metals of 4 to 6 periods and groups IV-XI of the periodic table supported on mesoporous materials. The inedible or edible vegetable oil may be palm oil or others. Triacylglycerides transform into a mixture of paraffin, propane, carbon dioxide, carbon monoxide, and water.

Also, document US2023332057, “Catalysts and selective process for the production of renewable aviation fuels and biofuel produced”, of Petróleo Brasileiro SA, with priority of Aug. 24, 2020, which discloses a process for converting vegetable oils, animal fats, residual edible oils and carboxylic acids into renewable liquid fuels, such as bionafta, bioJET-A1 and renewable diesel, for use in a mixture with fossil fuels. The process consists of two steps: hydrotreating and hydrocracking. The effluent from the hydrotreatment stage contains aromatics, olefins and compounds resulting from the polymerization of esters and acids. This is due to the use of partially reduced catalysts and without the injection of sulphide, and makes it possible to obtain a bioJET-A1 of suitable quality for use in a mixture with fossil kerosene. At the same time, the process generates, in addition to products from the naphtha distillation range, kerosene and diesel, linear paraffins of high molecular weight (up to 40 carbon atoms).

Finally, protection US2008229654, “Fuel Composition,” owned by Bradin David on Sep. 28, 2005, discloses compositions and methods for forming hydrocarbon products from triglycerides. In one aspect, the methods involve thermal decomposition of fatty acids, which may be derived from triglyceride hydrolysis. Thermal decomposition products can be combined with low molecular weight olefins, such as Fischer-Tropsch synthesis products, and subjected to molecular averaging reactions. Alternatively, the products may be subjected to hydrocracking reactions, isomerization reactions, and the like. The products can be isolated in the gasoline, aviation and/or diesel ranges. Thus, vegetable oils and/or animal fats can be converted using water, catalysts, and heat, into conventional products in the gasoline, aviation, and/or diesel ranges. These products are virtually indistinguishable from those derived from their petroleum-based analogues, except that they can have virtually no aromatic, sulfur or nitrogen content, are derived in whole or in part from renewable resources.

In view of the gaps in the technique, the proposed invention is a synergistic combination of pretreatment processes aimed at maximizing yields for green diesel and biokerosene, valuing co-products and increasing the durability of catalysts, bringing greater competitiveness with the integration of processes.

Any chemical analysis of vegetable oils and animal fats presents triglycerides, or triacylglycerols, as the main class of molecules present in this medium. In addition to diglycerides, monoglycerides and fatty acids, there is even, in lower concentrations, a non-negligible amount of other organic and inorganic compounds. We can cite carotenoids, tocopherols and phospholipids as other organic compounds and the presence in ppm concentrations of sodium, potassium, calcium, magnesium and iron as examples of inorganic impurities usually found in lipids. The HVO and HEFA processes make use of heterogeneous metal catalysts in continuous reactor catalytic beds. The life expectancy of these catalysts ranges from 12 to 18 months, but this is only possible with the significant reduction of impurities. A typical condition for the raw material to enter this process is: (P+Na+K+Ca+Mg)<10 ppm. To achieve this level of purity, the processes are not trivial. Some strategies should be taken to optimize this removal. For the removal of phospholipids, enzymatic degumming is the most indicated. Phospholipids are classified according to their degree of hydration (hydratable and non-hydratable). Hydratable phospholipids (HPL) become oil insoluble in the presence of water and are easily separated by centrifugation. Most non-hydratable phospholipids (NHPL) are complexed with calcium (Ca), magnesium (Mg) and iron (Fe) and, in order to be removed, they need the addition of a chelating agent (citric acid or EDTA) to sequester the metal ions, allowing them to be precipitated and separated by centrifugation. Enzymatic degumming is a process of removing phospholipids from crude oil by means of phospholipases (enzymes). Phospholipases hydrolyze the ester bonds present in phospholipid molecules, releasing diacylglycerols (DAGs) or free fatty acids (FFAs). The most commonly used phospholipases are: phospholipase A1 and phospholipase A2 which remove the fatty acid from position 1 and 2 relative to glycerol, and phospholipase C (PLC) which hydrolyzes the bond between the acylglycerol and the phosphate group to release diacylglycerols (DAG). In addition to phosphorus removal, the use of phospholipases has the advantage of increasing oil yield, decreasing effluent generation, and decreasing production costs. After this removal of the phospholipids by the enzymatic route, the oil must be hydrolyzed for efficient separation of the fatty acids from the glycerin. The glycerol present in triglycerides results in gases, especially propane. Through hydrolysis, glycerin is removed with high purity and, consequently, with a higher market value than propane. Another advantage of this route is the optimization of the HVO process that will receive only fatty acids, generating a higher hydrocarbon yield (about 90%, against 80% of the conventional process). Hydrogen consumption is reduced since there will be no hydrotreatment of glycerol. Several authors propose that this reaction is carried out in steps, starting from triglycerides to diglycerides, monoglycerides and glycerol, and at each step there is release of a fatty acid. This reaction is homogeneous of the first order in the oil phase. Because water and oil are insoluble at low temperature, the reaction at these conditions is extremely slow. By increasing the temperature, the solubility of the oil in water increases and the reaction rate accelerates rapidly. The degree of hydrolysis is not a function of temperature to obtain yield approximately equal to thermodynamic equilibrium at the temperature of 225, 240, and 280° C.; the reaction rates varied with temperature. The water-oil ratio is the limiting factor for this reaction. Yield at equilibrium is independent of the temperature or catalyst and is determined by the water-oil ratio. The reason is due to the fact that the displacement of the reaction occurs in the direction of the reactants with the increase in the concentration of glycerol; so it is of fundamental importance to control the percentage of water. The reactors in this process are typically continuous and counter-current and a reactive column is the most suitable system. At the top of the column comes out the fatty acid, less dense. At the bottom, the glycerin/water mixture comes out, which is subjected to controlled evaporation and treatment with ion exchange resins and activated carbon to obtain a minimum of 98% glycerin. This treatment has the additional advantage of removing from the oil or fat, practically all the presence of metal ions, such as sodium, potassium, calcium, iron, among others. After hydrolysis, the fatty acid mixture is vacuum dried and is able to receive adsorbents such as clays and silica for removal of traces of other impurities. Typically, after this step, filter presses remove the adsorbent particles. After that, the fatty acids are ready for the hydrotreating and hydroisomerization process, without prejudice to the catalysts of these steps, since the sum of metal ions plus phosphorus will be below 10 ppm. The biodiesel production process, known as the transesterification process, includes not only chemical reactors, but also the removal of glycerin, either by decantation or centrifugation. This removal itself removes much of the impurities from the oil from the ester phase. The biodiesel washing steps ensure virtually complete removal of organic impurities. Thus, we can also think of the use of methyl ester, that is, biodiesel, as a raw material for the production of HVO/SAF. Similarly to the alternative of using fatty acids obtained by hydrolysis, glycerin is preserved, which can be a co-product of significant value in the process.

Synergistic pre-processes for obtaining biofuels can be synthesized by their main steps: fatty acids are generated from the non-catalytic hydrolysis of oils and/or fats that occurs in countercurrent continuous reactors, in the temperature range between 250° C. and 300° C., pressure between 20 and 50 bar, in spatial time from 1 to 4 hours, with an oil/water feed mass ratio between 0.5 and 2; the oils are degummed by enzymatic degumming and the glycerin is recovered in the aqueous phase and concentrated and purified with ionic resins and activated carbon.

Alternatively the fatty acids and/or biodiesel are hydrotreated by commercial HVO and SAF catalysts, at the temperature of 300 to 350° C., pressure between 20 and 80 bar and the cold properties are adjusted to the conditions of green diesel, biokerosene or other derivative in a second continuous hydroisomerization reactor.

The invention can be better understood with the aid of the FIGURES.

FIG. 1 is a flowchart of the synergistic integration of the high-throughput pre-processes.

EXAMPLE 1

Example 1—Bovine tallow of acidity 5% was subjected to continuous hydrolysis without catalyst, at 270° C. and pressure of 30 bar. For every 100 kg of tallow, 100 kg of water was used, that is, a stoichiometric excess of water. Under the above reaction conditions and with a spatial time of two hours, 94 kg of fatty acid was obtained for every 100 kg of tallow. By subjecting this fatty acid to the hydrotreating process with Ni—Mo/Alumina catalyst, 340° C. and 70 bar, for 8 hours, 89 kg of liquid hydrocarbons were obtained for each 100 kg of fatty acids. This result is significantly higher than the yield obtained in the direct conversion of fats in the hydrotreatment, which is always less than 80%. In addition, as there is no hydrotreatment of glycerol (present in lipids) to propane, there is a lower total hydrogen consumption through this route.

Example 2—Soybean biodiesel was subjected to the hydrotreating process with Ni—Mo/Alumina catalyst, 340° C. and 70 bar, for 8 hours, 88.5 kg of hydrocarbons were obtained for each 100 kg of biodiesel. From oils and fats, the mass yield of conventional processes is always less than 80%. The same advantages observed in example 1 apply to example 2.

In summary, the new process brings the benefits of maximizing yields for green diesel and biokerosene production, enhancing co-products and increasing catalyst durability.

This invention is not limited to the representations commented or illustrated herein, and should be understood in its broad scope. Many modifications and other representations of the invention will come to the mind of one skilled in the art to which this invention belongs, having the benefit of the teaching presented in the previous descriptions and attached drawings. Furthermore, it is to be understood that the invention is not limited to the specific form disclosed, and that modifications and other forms are understood to be included within the scope of the appended claims. Although specific terms are employed herein, they are used only in a generic and descriptive manner and not for the purpose of limitation.