Patent Grant
11767484
Embodiments of the subject matter disclosed herein generally relate to a composition and method for making the composition, where the composition is a bio-lubricant made from waste cooking oil using a biochar as a catalyst and adsorbent, and more particularly, to using an animal-based biochar for making an adsorbent and a catalyst to be used in a specific chemical process for transforming used cooking oil into a bio-lubricant with a high viscosity point.
Lubricants perform as anti-friction media. They facilitate smooth operations, maintain reliable machine functions, and reduce the risks of frequent failures. At present, the high price of the crude oil, the restrictive distribution of the crude oil reserves in the world, and the shared concern in protecting the environment from pollution have renewed interest in developing and using environment-friendly lubricants derived from alternative sources, for example, a bio-lubricant obtained from waste cooking oil. A bio-lubricant is a renewable lubricant that is biodegradable, non-toxic, and does not add to the natural carbon cycle. Bio-lubricants are used today mainly as hydraulic fluids, lubricants for power tools (e.g., chainsaws), and potentially as motor lubricating fluids.
Bio-lubricants are biodegradable and non-toxic to humans and the environment, in particular to aquatic environments. For instance, vegetable oils have been applied for lubrication purposes for many years. They are known for their biodegradability, high lubricity, viscosity index, and flash point. Practices of using vegetable oils for lubricant applications is not completely new in the market. The technology to process bio-based feedstocks and to produce base oils for lubricants has been adopted by some key lubricant organizations for several years. These companies have added bio-based lubricants to their product portfolio.
However, bio-based lubricants also have several disadvantages. First, the discovery of petroleum and the availability of low-cost mineral oils make the utilization of bio-lubricants less competitive in the market. Second, bio-based lubricants are derived from renewable materials, frequently vegetable-based. These include rapeseed oil, sunflower oil, coconut oil, palm oil and soybean oil; these virgin renewable resources come with more disadvantages as (1) the virgin renewable resources are around 40-50% more expensive compared with conventional base oils, and (2) the virgin vegetable oil could potentially compete with the food value chain turning it into a rather unsustainable feedstock and product value chain.
Therefore, alternatives from waste feedstock are favoured in preparing bio-based lubricants, such as waste animal fats and used vegetable cooking oils (UVCOs). However, a problem with the process of manufacturing the bio-based lubricants is the cost and complications of separation encountered by the UVCOs esters currently used in these processes. Predominantly, the catalysts used to produce esters at industrial scales are homogeneous in phase with the oil. Further, the current catalysts are harmful to humans and the environment in general. Due to the above-mentioned problems (i.e., costs and complications of separation of catalysts from the product stream), their utilization has been discouraged lately. Other major disadvantages of homogeneous catalysts are recycling/recovery of the catalyst and generation of additional waste streams. These limitations were partly addressed by supercritical processes as no catalysts are used and high yields are achieved in short duration [1]. However, the costs associated with the installation and maintenance of such supercritical equipment capable of withstanding such high pressures make this process unattractive. In addition, traditional methods for producing biolubricants from UVCO do not meet the requirements for applications needing higher viscosity grades.
Thus, there is a need for a new process for generating bio-lubricants from waste cooking oil, that is not expensive, does not require sophisticated equipment, and the catalysts are also bio-based and not harmful to the environment.
According to an embodiment, there is a bio-lubricant composition that includes a first component that includes a first triglyceride, which is part of a waste cooking oil, a second component that includes a first epoxidized triglyceride, a third component that includes a hydroxylated triglyceride, a fourth component that includes a first fatty acid ester moiety, a fifth component that includes a first epoxidized fatty acid ester, and a sixth component that includes a hydroxylated fatty acid ester. A mixture of the first to sixth components at room temperature has a viscosity between 40 and 200 centipoise, and the composition is substantially free of free fatty acids.
According to another embodiment, there is a bio-lubricant composition that includes a first component that includes a first triglyceride, which is part of waste cooking oil, a second component that includes a first epoxidized triglyceride, which originates from a second triglyceride, which is part of the waste cooking oil, wherein the second triglyceride has been epoxidated to obtain the first epoxidized triglyceride, a third component that includes a hydroxylated triglyceride, which originates from a third triglyceride of the waste cooking oil, wherein the third triglyceride was epoxidized to form a second epoxidized triglyceride and the second epoxidized triglyceride was hydroxylated to form the hydroxylated triglyceride, a fourth component that includes a first fatty acid ester moiety, which originates from a first free fatty acid of the waste cooking oil, a fifth component that includes a first epoxidized fatty acid ester, which originates from a second free fatty acid of the waste cooking oil, and the second free fatty acid was esterified to form a second fatty acid ester moiety and the second fatty acid ester moiety was epoxidated to form the first epoxidized fatty acid ester, and a sixth component that includes a hydroxylated fatty acid ester, which originates from a third free fatty acid of the waste cooking oil, and the third free fatty acid was esterified to form a third fatty acid ester moiety, the third fatty acid ester moiety was epoxidated to form a second epoxidized fatty acid ester, and the second epoxidized fatty acid was hydroxylated to form the hydroxylated fatty acid ester. A mixture of the first to sixth components at room temperature has a viscosity between 40 and 200 centipoise, and the composition is substantially free of free fatty acids.
According to yet another embodiment, there is a method for making a bio-lubricant composition from waste cooking oil, and the method includes purifying the waste cooking oil with an activated biochar to obtain purified cooking oil, wherein the purified cooking oil includes triglycerides and free fatty acids, esterifying the purified cooking oil to transform substantially all the free fatty acids into fatty acid methyl ester moieties, wherein this step maintains a viscosity of the purified cooking oil when transformed into a first mixture of the triglycerides and the fatty acid methyl ester moieties, stabilizing a structure of the triglycerides and the fatty acid methyl ester moieties by epoxidation, which results in a second mixture of epoxidated triglycerides, epoxidated fatty acid esters, the triglycerides, and the fatty acid methyl ester moieties, and increasing the viscosity of the second mixture by opening epoxy rings with a hydroxylation process, which results in a third mixture of the triglycerides, the fatty acid methyl ester moieties, the epoxidated triglycerides, the epoxidated fatty acid esters, hydroxylated triglycerides, and hydroxylated fatty acid esters. The third mixture at room temperature has a viscosity between 40 and 200 centipoise.
For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
The following description of the embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. The following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. The following embodiments are discussed, for simplicity, with regard to forming a bio-lubricant from waste cooking oil using an animal-based biochar as a catalyst and adsorbent. However, one skilled in the art would understand that the embodiments to be discussed next are not limited to waste cooking oil or animal-based biochar, but may be applied to other sources, and/or with other catalysts and/or absorbents.
Reference throughout the specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.
It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first object or step could be termed a second object or step, and, similarly, a second object or step could be termed a first object or step, without departing from the scope of the present disclosure. The first object or step, and the second object or step, are both, objects or steps, respectively, but they are not to be considered the same object or step.
The terminology used in the description herein is for the purpose of describing particular embodiments and is not intended to be limiting. As used in this description and the appended claims, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term “and/or” as used herein refers to and encompasses any possible combinations of one or more of the associated listed items. It will be further understood that the terms “includes,” “including,” “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. Further, as used herein, the term “if” may be construed to mean “when” or “upon” or “in response to determining” or “in response to detecting,” depending on the context.
According to an embodiment, a method for converting used vegetable cooking oil (UVCO) into bio-based lubricants using multifunctional biochar as adsorbent and catalyst is discussed. Biochars are promising materials produced from different thermochemical processes such as hydrothermal carbonization, hydrothermal liquefaction, gasification and pyrolysis. Biochars have been used for high-end applications such as catalyst support apart from toxic metal removal from wastewater, chemical and biodiesel production from biomass and soil amendment. The process of obtaining a biochar for the novel method of converting UVCOs into a biolubricant may be based on the process disclosed in International Patent Application PCT/IB2021/061146 (herein, “the '146 PCT application”), belonging to the assignee of the present application, the entire content of which is included herein by reference. The process disclosed in the '146 PCT application integrates biological processes and thermochemical conversion to give poultry waste a second life.
The use of the biochar obtained from poultry waste (note that a biochar obtained through other paths may also be used) not only establishes a greener process of treating the low-graded UVCOs, but also addresses one or more of the following problems: it replaces the conventional homogeneous catalysts (i.e., sulfuric acid) for the esterification process, as they are corrosive and difficult to recycle from the process, and/or applies renewable biochar adsorbents as produced from other waste streams (e.g., chicken manure, biomass).
The various aspects of the invention are now discussed with regard to the figures. First, the preparation of the biochar as adsorbent and catalyst is discussed followed by the process of treating the UVCOs to obtain the bio-lubricants. As illustrated in
The same raw biochar 110 may be differently activated in step 122 to generate a biochar catalyst 124 by treating the biochar 110 with sulfuric acid 126. Part of the acid 126 is recovered in step 128 by known methods. For example, in step 122, each 10 g of the raw biochar 110 are treated with 4.5 g of acid 126 to generate the biochar catalyst 124. The two activation processes 112 and 122 discussed above are schematically illustrated in
Next, a novel process for transforming the UVCO into a high viscosity bio-lubricant is discussed.
The method further includes a step 302 of purifying the waste cooking oil 400 with the activated carbon 114 to obtain purified cooking oil 410, where the purified cooking oil 410 includes triglycerides 401 to 403 (two possible chemical structures are illustrated in
An objective of the purification step 302 is to remove impurities obtained from different sources. The activated biochar 114 adsorbs small, polar organic molecules resulting from the high-temperature cooking and contact with various food resources. The adsorbent performance of the biochar 114 is controlled by the average pore diameters and pore volumes of the biochar and related molecular mechanisms. The purification potential of the activated biochar is attributed to the molecular diffusion and physic/chemisorption. The decomposed peroxide molecules and fatty acids of the waste cooking oil have molecule sizes ranging from 0.8 to 1.5 nm, which are much smaller than that of triglycerides (c.a. 5.8 nm). The small molecules adsorb on the biochar adsorbent 114 and are removed by subsequent precipitation and centrifugation processes (not shown). The total surface area and number of oxygenated functionalities are selected in the acid-based catalyst for the esterification of UVCOs. The oxygenated functionalities on the biochar serve as proton donors to catalyze the esterification of fatty acids with alcohol. The total surface area determines the catalytic efficiencies. The purification efficiency depends on the activated biochar applied.
In step 304, the purified cooking oil 410 is esterified to transform all the free fatty acids 404 to 406 into fatty acid methyl ester moieties 414, 415, and 416, where this step maintains a viscosity of a first mixture 420, which includes the triglycerides 401 to 403 and the fatty acid methyl ester moieties 414 to 416. Note that the first mixture 420 is obtained as a result of the esterification of the purified cooking oil 410. Also note that the term “all” used above to indicate that all the free fatty acids 404 to 406 have been esterified means that substantially all of them have undergo this transformation. One skilled in the art would understand that in chemistry, there is always the possibility that traces of the original substances or molecules have not been transformed, and a trace amount of them may be found in the final product. However, these trace elements of the unreacted compound are small and typically ignored when analyzing and reporting the composition of the reacted product. In one application, the amount of free fatty acids found in the first mixture 420 is smaller than 1% of the total mass of the first mixture, and thus, they are considered to be non-existent.
As a result of the esterification step 304, the free fatty acids have been transformed into fatty acids methyl esters 414 to 416, which are schematically illustrated in
The esterification step 304 is performed with a homogenous catalyst, i.e., the sulfuric acid. In one application, the purified cooking oil was first mixed with the methanol and then the sulfuric acid was slowly added to the mixture. The final product, which is a sweet smelling product, was transferred to a separation funnel (not shown). There were two phases observed in the separation funnel. The phase observed in the bottom was water, sulfuric acid and unreacted methanol. The esterified purified UVCO (i.e., the first mixture 420) was at the top and it was collected for subsequent reactions.
In step 306, the structure of some of the triglycerides 401 to 403 and some of the fatty acid methyl ester moieties 414 to 416 is stabilized by epoxidation, which results in a second mixture 430, which includes epoxidated triglycerides 422 and 423, epoxidated fatty acid esters 425 and 426, the triglycerides 401, and the fatty acid methyl ester moieties 414, as schematically illustrated in
The second reaction unit 520′ receives the first mixture 420 from the first reaction unit 520, and also receives sulfonated carbon 124 (which acts as the heterogenous catalyst for the epoxidation reaction) from a first tank 550, hydrogen peroxide 120 from a second tank 552, and an acid 540 (for example, acetic acid) from a third tank 554. In one application, for each 1 kg of the first mixture 420, about 5% of the weight of the first mixture, which is about 50 g, of the sulfonated carbon, about 77% of the weight of the first mixture, which is about 774 g, of the sulfuric acid, and about 155 g of acetic acid are added to the inner tank 522′ for the epoxidation reaction. The reaction takes place at about 60° C., for 6 h, while the stirrer 508 rotates at about 600 rpm. Note that the controller 510 is configured to add the hydrogen peroxide 120 in a dropwise manner. Further note that a heterogenous catalyst has been used in this step, which is derived from the activated biochar 124, thus replacing the use of a corrosive acid, like the sulfuric acid. To the contrary, the esterification step 304 used a homogenous catalyst, i.e., the sulfuric acid.
The chemical structures of the epoxidated triglycerides 422 and 423 are illustrated in
For increasing the viscosity of the resulting second mixture 430, the epoxy rings 800 (see
The hydroxylation step is performed for branching in the final molecule and
In this step, an alcohol (e.g., 1-hexanol) 562 in the presence of activated carbon/biochar catalyst 124 was used to open the rings 800 present in the epoxidized UVCO mixture 430. In a hydroxylation reactor 520″, which can be similar to the reactor 520 or 520′, for each 1 kg of the second mixture 430 (i.e., the epoxidized purified UVCO), 20 g of activated carbon catalyst 124 was added and stirred at about 600 rpm. Then, for each 1 kg of the second mixture 430, about 182 g of 1-hexanol 562 was added and the stirring process was continued. The temperature inside the inner container 522″ was raised to 80° C. and the mixture was kept at this temperature for 2 h. After 2 h, the third mixture 440 was generated and then it was filtered to remove the activated carbon. The filtered product is the final bio-lubricant base oil 450. Note that the alcohol 562 is stored in a corresponding tank 564.
At a minimum, according to this embodiment, the final composition 450 includes six different groups of molecules (or components) 441 to 446, where the first group or component 441 includes the first triglyceride 401, the second component 442 includes the first epoxidized triglyceride 422, the third component 443 includes the hydroxylated triglyceride 433, the fourth component 444 includes the first fatty acid ester moiety 414, the fifth component 445 includes the first epoxidized fatty acid ester 425, and the sixth component 446 includes the hydroxylated fatty acid ester 436. It was observed that a mixture of the first to sixth components at room temperature has a viscosity between 40 and 200 centipoise, and the composition 450 is substantially free of free fatty acids.
The first epoxidized triglyceride 422 originates from the second triglyceride 402, which is part of the cooking oil 400, and the second triglyceride 402 has been epoxidated to obtain the first epoxidized triglyceride 422. The hydroxylated triglyceride 433 originates from the third triglyceride 403 of the cooking oil 400, where the third triglyceride 403 was previously epoxidized to form the second epoxidized triglyceride 423 and the second epoxidized triglyceride 423 was hydroxylated to form the hydroxylated triglyceride 433.
The first fatty acid ester moiety 414 originates from the first free fatty acid 404 of the cooking oil 400 and was obtained from the esterification of the first free fatty acid 404. The first epoxidized fatty acid ester 425 originates from the second free fatty acid ester 405 of the cooking oil 400, and the second free fatty acid 405 has been esterified to form the second fatty acid ester moiety 415 and the second fatty acid ester moiety 415 has been epoxidated to form the first epoxidized fatty acid ester 425. The hydroxylated fatty acid ester 436 originates from the third free fatty acid 406 of the cooking oil 400, and the third free fatty acid 406 has been esterified to form the third fatty acid ester moiety 416, the third fatty acid ester moiety 416 has been epoxidated to form the second epoxidized fatty acid ester 426, and the second epoxidized fatty acid ester 426 has been hydroxylated to form the hydroxylated fatty acid ester 436.
The inventors have studied the chemical composition of the composition 450 and they found traces of the biochar 114/124 that is used as a catalyst and absorbent, where the biochar is feedstock based. In this regard, the carbon/biochar 110 was treated with sulfuric acid to produce the activated carbon 124 with sulfonyl sites. A mixture with sulfuric acid (98%) and water in the ratio of 80:20 (v/v) was prepared in one application. About 50 g of the activated carbon was mixed with 950 g sulfuric acid-water mixture. This mixture was heated to 80° C. and stirred at 600 rpm using a magnetic stirrer for 12 h. After 12 h, this activated carbon was then washed with distilled water (ambient conditions) and filtered (similar filtration procedure). The recovered activated carbon 124 with sulfonyl sites was dried in an oven at 120° C. for 8 h.
From the chemical analysis of the composition 450, the inventors found that the biochar activated as an adsorbent 114 (for the catalyst 124, additional products may be present) has the composition shown in the table of
The type of UVCO-derived fatty acid methyl esters (FAMEs) and those derived from vegetable cooking oil (VCO) are illustrated in
The branching imparted to the third mixture 440 in step 308 controls the viscosity of the final composition 450. The inventors have measured the viscosity of the synthesized bio-lubricant base oil 450 and when compared to the International Standard Organization (ISO) graded lubricant oils, the results are as presented in the table of
Ball wear scars were generated for different oil lubrications (not shown). The ball wear scars resulted from frequent metal-to-metal contacts and subsequent adhesive forces that remove contacting surface material. Lubrication with UVCO bio-lubricant 450 reduced the ball wear scar size by approximately 20% as compared to Group II base oil 1410. The carbonyl and hydroxyl groups present in the UVCO-derived bio-lubricant 450 enhanced the molecular interaction with the metallic surfaces, forming protective oil films that reduce surface material wear. The addition of multifunctional polyether to the UVCO bio-lubricant could synergize with UVCO bio-lubricant and further reduced ball wear scar by 25%.
One of the advantages of the UVCO bio-lubricant 450 over the synthetic lubricants listed in
Other advantages that may be achieved with the composition 450 discussed above includes: reusing the biochar produced from chicken manure, reducing the corrosive acid use in bio-lubricant productions, recycling the biochar adsorbent and catalysts from bio-lubricant productions, removing hazardous contaminates and chemicals from the process, reducing the amount of energy lost to friction in moving parts by providing a superior biolubrication, removing the use of fossil derived lubricants, reusing waste and used cooking oil that would be destined for disposal or combustion, and removing carbon emissions by creating durable carbon in the form of long lifetime bio-lubricants. The process discussed above with regard to
The disclosed embodiments provide a method for making a bio-lubricant with enhanced properties and a bio-lubricant composition with a viscosity between 40 and 200 centipoise, based on waste cooking oil. It should be understood that this description is not intended to limit the invention. On the contrary, the embodiments are intended to cover alternatives, modifications and equivalents, which are included in the spirit and scope of the invention as defined by the appended claims. Further, in the detailed description of the embodiments, numerous specific details are set forth in order to provide a comprehensive understanding of the claimed invention. However, one skilled in the art would understand that various embodiments may be practiced without such specific details.
Although the features and elements of the present embodiments are described in the embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the embodiments or in various combinations with or without other features and elements disclosed herein.
This written description uses examples of the subject matter disclosed to enable any person skilled in the art to practice the same, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the subject matter is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims.
The entire content of all the publications listed herein is incorporated by reference in this patent application.
This application claims priority to U.S. Provisional Patent Application No. 63/323,137, filed on Mar. 24, 2022, entitled “BIOCHAR AS ADSORBENT AND CATALYST FOR CLEAN BIOLUBRICANT PRODUCTION,” and U.S. Provisional Patent Application No. 63/432,716, filed on Dec. 15, 2022, entitled “BIO-LUBRICANT WITH HIGH VISCOSITY AND METHOD,” the disclosures of which are incorporated herein by reference in their entirety.
| Number | Name | Date | Kind |
|---|---|---|---|
| 8809026 | Vanhercke | Aug 2014 | B2 |
| Number | Date | Country |
|---|---|---|
| WO 2022118198 | Jun 2022 | WO |
| Entry |
|---|
| Bullo, T.A., et al., “Biosynthesis of Sulfonated Carbon Catalyst from Carbohydrate Polymer Derivatives for Epoxidation of Croton Macrostachyus Seed Oil,” Carbohydrate Polymer Technologies and Applications, Jun. 2022 (available online May 26, 2022), vol. 3, 100221, pp. 1-8, Elsevier. |
| Musik, M., et al., “Advanced Methods for Hydroxylation of Vegetable Oils, Unsaturated Fatty Acids and Their Alkyl Esters,” Coatings, 2022 (published Dec. 23, 2021), vol. 12, No. 13, pp. 1-18. |
| Rios, L., et al., “Hydroxylation of Vegetable Oils using Acidic Resins as Catalysts,” Industrial Crops and Products, May 2013, vol. 43, pp. 183-187, Elsevier B.V. |
| Warabi, Y., et al., “Reactivity of Triglycerides and Fatty Acids of Rapeseed Oil in Supercritical Alcohols,” Bioresource Technology, Feb. 2004, vol. 91, No. 3, pp. 283-287, Elsevier Ltd. |
| Borugadda, V.B., et al., “Hydroxylation and hexanoylation of epoxidized waste cooking oil and epoxidized waste cooking oil methyl esters: Process optimization and physico-chemical characterization,” Industrial Crops & Products, vol. 133, 2019 (Available online Mar. 14, 2019), pp. 151-159. |
| Borugadda, V.B., et al., “Physicochemical and Rheological Characterization of Waste Cooking Oil Epoxide and Their Blends,” Waste Biomass Valor, vol. 7, 2016 (Published online Sep. 23, 2015), pp. 23-30. |
| International Search Report and Written Opinion of the International Searching Authority (Forms PCT/ISA/220, PCT/ISA/210 and PCT/ISA/237), dated May 31, 2023, for corresponding/related International Application No. PCT/IB2023/052873. |
| Zhang, W., et al., “Green preparation of branched biolubricant by chemically modifying waste cooking oil with lipase and ionic liquid,” Journal of Cleaner Production, vol. 274, Article 122918 Nov. 20, 2020, pp. 1-11. |
| Number | Date | Country | |
|---|---|---|---|
| 63432716 | Dec 2022 | US | |
| 63323137 | Mar 2022 | US |
