Method for preparing base oil from tire pyrolysis oil and base oil obtainable using method
By applying hydrogen processing and distillation to TPO, the method addresses the commercial shortcomings of TPO-derived oils, producing base oil with low sulfur and improved properties for industrial use.
Patent Information
- Application Number
- CN202380079605.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-11-16
- Filing Date
- 2023-11-13
- Publication Date
- 2025-07-15
AI Technical Summary
It is difficult to prepare base oils that meet commercial standards from tire pyrolysis oils, especially the problems of high sulfur content, unclear appearance and low aniline points.
By performing hydrotreating and distillation steps on the tire pyrolysis oil, appropriate conditions are selected to minimize hydrocracking and viscosity reduction, base oils that meet commercial standards are prepared using base metal catalysts.
The obtained base oil has a sulfur content of less than 1.0% by weight, a clear appearance, aniline point is higher than 50°C, and has good low temperature properties and biosource carbon content, which meets the basic requirements of commercial base oil.
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Figure CN120322526A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for preparing base oil from tire pyrolysis oil, and to a base oil obtainable by this method, which base oil exhibits a biogenic carbon content of at least 1% as determined by the ASTM D6866 method. Background Art
[0002] Waste tires are abundant, and there is a growing interest in converting waste tires into useful products such as carbon black, fuel, and oil. It is known to prepare pyrolysis oil (also known as cracker oil) from waste tires. This pyrolysis oil is also referred to as end-of-life tire pyrolysis oil, scrap tire pyrolysis oil, waste tire pyrolysis oil.
[0003] There is a desire to be able to prepare base oil from tire pyrolysis oil (TPO) that can be used in any typical specialty oil application, such as but not limited to metalworking fluids, lubricating oils, greases, transmission fluids, oils for tires and other rubber compounds.
[0004] Okoro et al. concluded in "Modification of waste tire pyrolytic oil as base fluid for synthetic lube oil blending and production: waste tire utilization approach" published in Journal of Material Cycles and Waste Management on March 27, 2020, that waste tire pyrolysis oil can be used as a base oil for lubricants after distillation to remove light hydrocarbon components and sulfur. However, the resulting base oil produced in the study by Okoro et al. was described as a dark brown oily liquid with a strong pungent smoky odor, which may be due to its sulfur content (1.58 wt%). The aniline point of the waste tire pyrolysis oil reported therein at 18 °C indicates a high aromatic compound content. However, no aniline point was reported for the base oil obtained therein. For a base oil to be commercially acceptable, a lower sulfur content is generally required, such as at most 1.0 wt%. In addition, the appearance should preferably be clear and bright, and the aniline point is generally at least 50 °C. Okoro et al. suggested that additives can be used to affect the physical and chemical properties of the base oil produced from waste tires.
[0005] There is still a need for alternative methods for preparing base oil. Preferably, the base oil should meet the basic criteria of conventional commercial base oils, such as sulfur content, appearance, and aniline point.
[0006] The object of the present invention is to provide a method for preparing a base oil from TPO having an acceptable sulfur content, namely a sulfur content of at most 1.0 wt%. Summary of the Invention
[0007] According to the present invention, this object is achieved by subjecting the TPO feedstock to a hydroprocessing step comprising a hydrotreating step and a subsequent distillation step, or to a distillation step and a subsequent hydroprocessing step comprising a hydrotreating step. Base oils meeting the basic criteria of conventional commercial base oils can be obtained by the method of the present invention, the basic criteria being related to the sulfur content, and preferably also related to one or more of the following: appearance, aniline point (related to aromaticity), and acidity. TPO typically has a high acidity. By the method according to the present invention, a base oil with an acceptable acidity can be obtained from TPO.
[0008] According to the present invention, the order of the distillation step and the hydroprocessing step is not important.
[0009] Thus, in one aspect, the present invention relates to a method for preparing a base oil from tire pyrolysis oil, comprising the steps of: subjecting the tire pyrolysis oil to a hydroprocessing step comprising a hydrotreating step to obtain a hydroprocessed tire pyrolysis oil, wherein the hydrotreating step is carried out in the presence of a base metal catalyst at a pressure in the range of 50 - 170 bar, a temperature in the range of 290 - 370 °C, and a liquid hourly space velocity in the range of 0.4 - 2.0 h -1 -1; and distilling the hydroprocessed tire pyrolysis oil obtained from the hydroprocessing step to obtain at least two fractions, thereby obtaining a base oil as at least one fraction.
[0010] In another aspect, the present invention relates to a method for preparing a base oil from tire pyrolysis oil, comprising the steps of: distilling the tire pyrolysis oil to obtain one or more fractions; and subjecting the one or more fractions obtained from the distillation step to a hydroprocessing step comprising a hydrotreating step, wherein the hydrotreating step is carried out in the presence of a base metal catalyst at a pressure in the range of 50 - 170 bar, a temperature in the range of 290 - 370 °C, and a liquid hourly space velocity in the range of 0.4 - 2.0 h -1 -1 to obtain one or more hydroprocessed fractions, thereby obtaining one or more base oils.
[0011] The conditions selected for use in the hydroprocessing step of the present invention are such that the degree of hydrocracking is minimized, the reduction in viscosity is minimized, and any ring-opening reactions are minimized. Thereby, a resulting product with more naphthenic characteristics can be obtained.
[0012] In a preferred embodiment, the catalytic dewaxing step comprises being carried out in the hydroprocessing step of the method of the present invention, which is preferably carried out after the hydrotreating step. The catalytic dewaxing step can be used to improve the low-temperature properties of the obtained base oil.
[0013] The method of the present invention allows the use of co-feeds such as any one of pyrolysis oil from plastic waste, crude oil, crude oil distillates, VGO, used oil and waste oil, or any mixture thereof.
[0014] Thus, in one embodiment, waste oil, used oil, pyrolyzed plastic waste oil, crude oil, crude oil distillates, VGO or any combination thereof is provided as a co-feed to the TPO. The co-feed used can be in the range of 5 - 95 wt%, more preferably up to 70 wt%, and even more preferably up to 30 wt%.
[0015] When the TPO is prepared from tires of rubber having a biogenic carbon content such as natural rubber, the TPO will exhibit a biogenic carbon content. In particular, the natural rubber content of truck tires is high.
[0016] According to the present invention, it has been found that the resulting base oil will exhibit a biogenic carbon content similar to that of the feedstock used. Therefore, in order to achieve a high biogenic content of the resulting base oil, TPO prepared from truck tires is preferred. As an example, when a feedstock having a biogenic carbon content of at least 5 wt% is used, the resulting base oil will exhibit a biogenic carbon content of at least 5 wt%. The TPO obtained from truck tires can exhibit a biogenic carbon content of about 50 wt%.
[0017] Thus, in another aspect, the present invention relates to a substantially oxygen-free base oil having a sulfur content of not more than 1 wt%, obtainable by the above method, the base oil exhibiting a biogenic carbon content of at least 1 wt% determined by the ASTM D6866 method and a viscosity index (VI) of not more than 110.
[0018] The disadvantage of prior art non-TPO-derived biogenic base oils, which typically have a biogenic carbon content in the range of 50 - 100%, is an overly high viscosity index, usually higher than 120. In addition, other prior art biogenic base oils prepared from plant-derived feedstocks tend to contain oxygen, which negatively affects the performance and stability of the base oil.
[0019] In summary, by using TPO, a stable base oil can be obtained, which has a biogenic content corresponding to the biogenic content of the rubber from which the TPO is obtained, while avoiding the hydrodeoxygenation (HDO) step. The base oil also has a higher viscosity than known substantially oxygen-free alternative base oils having a biogenic content.
[0020] TPO generally exhibits an oxygen content of less than 5 wt%, more typically an oxygen content of less than 2 wt%, such as an oxygen content of 1 - 2 wt%.
[0021] Other embodiments and advantages of the present invention will be apparent from the following detailed description and the appended dependent claims.
[0022] The term "pyrolysis oil from tires" as used herein is intended to cover any oil obtained by pyrolysis of rubber from tires. This oil may also be referred to as end-of-life tire pyrolysis oil, scrap tire pyrolysis oil, waste tire pyrolysis oil, etc.
[0023] The term "base oil" as used herein is intended to refer to a product that meets the basic criteria of a conventional commercial base oil, in particular a sulfur content of at most 1 wt%, and preferably one or more of the following: appearance, aromaticity (represented by the aniline point), and acidity. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 An overview of the method of the present invention is schematically shown, wherein, in route A, the distillation step precedes the hydroprocessing step, and in route B, the hydroprocessing step precedes the distillation step. In the illustrated embodiment, the distillation step produces two or more fractions, at least one of which is a base oil (route B), or produces a fraction that becomes a base oil after hydroprocessing (route A). DETAILED DESCRIPTION
[0025] The method of the present invention is based on a hydroprocessing step that includes a hydrotreating step and a distillation step.
[0026] According to the present invention, it has been found that the sulfur content obtained by the above two steps is at most 1 wt%, and the same process steps are also used to ensure a suitable aromaticity of the base oil, and thus the aniline point is ensured. The aniline point is affected by viscosity and aromaticity, and is generally well above 50 °C even for TPO-based base oils.
[0027] In the distillation step, the feedstock (see route A in Figure 1 ) or the effluent from the hydroprocessing step (see route B in Figure 1 ) is distilled into two or more fractions. The distillation step is typically carried out at a distillate boiling range of 280 - 500 °C.
[0028] To obtain a base oil with improved low-temperature properties, a catalytic dewaxing step is preferably included in the hydroprocessing step. The catalytic dewaxing step is carried out using a base metal dewaxing catalyst. When included, the catalytic dewaxing step is typically carried out in the following ranges: a pressure in the range of 100 - 160 bar; a temperature in the range of 350 - 400 °C; a LHSV in the range of 0.4 - 2.0 h -1 range. When included, the hydrorefining step is carried out in ranges similar to those used for the hydroprocessing step described above.
[0029] The method of the present invention allows the use of co-feeds such as plastic waste pyrolysis oil, crude oil, crude oil distillates, VGO, used oil or waste oil, or any mixture thereof.
[0030] The raw materials for the method of the present invention should preferably meet certain criteria regarding the impurity levels therein, especially when pyrolysis oil from plastic waste is used as a co-feed.
[0031] Specifically, the content of the following contaminants in the raw materials or co-feeds to be used in the method of the present invention may have to be reduced: particles, water, halogens (especially chlorine and bromine), and silicone.
[0032] For this purpose, depending on the purity of the raw materials and co-feeds to be used in the method, a pretreatment step for reducing the presence of one or more of the above-mentioned contaminants is preferably included in the method of the present invention.
[0033] Base metal catalysts are used in the hydrotreating step. The catalyst is preferably based on Ni, Mo, Co, W, or any combination thereof.
[0034] Base metal catalysts are used in the catalytic dewaxing step. The catalyst is preferably based on Ni, Mo, W, or any combination thereof.
[0035] A hydrofinishing step is preferably included in the hydroprocessing step of the method of the present invention. When used, the order of the different steps in the hydroprocessing step is preferably as follows: hydrotreating, catalytic dewaxing, and finally hydrofinishing.
[0036] The method of the present invention does not require the use of noble metal catalysts. Thus, according to the present invention, a high-pressure separation step for separating unwanted gases (such as NH3, H2S, etc.) and its associated equipment are not required, the presence of which would deactivate noble metal catalysts (if used).
[0037] In a preferred embodiment, the catalysts used in the method of the present invention are selected from base metal catalysts.
[0038] In a preferred embodiment, the method of the present invention does not include a hydrodeoxygenation (HDO) step.
[0039] In a preferred embodiment, the method of the present invention does not include a hydrocracking step.
[0040] In a preferred embodiment, the resulting base oil is suitable for use at low temperatures and includes a large amount of biogenic carbon content. The base oil has a viscosity of 3 - 700 cSt at 40 °C, preferably 3 - 450 cSt at 40 °C. The base oil is typically naphthenic.
[0041] The viscosity index of the base oil is preferably not greater than 110, more preferably not greater than 100, and particularly preferably not greater than 95.
[0042] The base oil of the present invention preferably has a nitrogen content of less than 100 ppm, more preferably less than 40 ppm, such as less than 20 ppm, and even more preferably less than 10 ppm; and preferably has a sulfur content of less than 100 ppm, more preferably less than 50 ppm, especially less than 20 ppm.
[0043] The base oil of the present invention preferably exhibits an aromatic content suitable for typical base oil applications, including a polycyclic aromatic hydrocarbon (PAH) content of 10 specified PAHs of less than 10 mg / kg determined using the measurement method EN 16143, and a PCA content of less than 3 wt% determined according to IP346.
[0044] The aniline point of the base oil of the present invention determined using the standard method ASTM D611 is typically at least 50 °C.
[0045] The base oil preferably has low-temperature properties suitable for base oil applications according to the oil standard methods ASTM D7346 and ASTM D97.
[0046] The base oil obtainable by this method preferably exhibits a biogenic carbon content of at least 1%, preferably at least 5%, more preferably at least 10%, more preferably at least 30%, and even more preferably at least 50%, determined using the method ASTM D6866. As described above, the feedstock of the process, i.e., only TPO or TPO with a co-feed, should be selected to exhibit a biogenic carbon content corresponding to the desired biogenic carbon content of the resulting base oil.
[0047] Examples
[0048] Example 1
[0049] In this example, a base oil was prepared from commercially available TPO. The properties of the TPO used, as well as the standard measurement methods used, have been set forth in Table 1 below. In this example, in the first step, the TPO was subjected to a TPO distillation / fractionation step to obtain a TPO distillate. Then, in the second step, the TPO distillate was subjected to hydrotreating to obtain a base oil. In the third step, the properties of the resulting base oil were further improved by subjecting the base oil to a dewaxing step. In the fourth step, the improved base oil from the third step was subjected to hydrofining. The details of this method will be further described below.
[0050] The properties of the TPO used have been set forth in Table 1 below.
[0051] Table 1. TPO properties
[0052]
[0053] Subject the TPO to distillation. Then blend the fractions obtained from the distillation to produce the TPO distillate feed used in Example 1. Table 2 shows the properties of the TPO distillate feed and the measurement methods used.
[0054] Table 2. TPO Distillate Feed Used in Example 1
[0055]
[0056]
[0057] Perform the hydrotreating step (2) using a base metal catalyst (NiMo) with the aim of removing sulfur, nitrogen and saturating aromatic compounds. The operating conditions of step 2 are shown in Table 3 below, and the properties of the resulting product (i.e., base oil) from step 2 are shown in Table 4 below.
[0058] Table 3. Hydrotreating Operating Conditions of Step 2
[0059]
[0060] Table 4. Properties of the Liquid Product (Base Oil) from Step 2
[0061]
[0062] The aim of step 3 is to improve the cold flow properties of the liquid product from step 2. A commercial metal-based catalyst (nickel) and zeolite are used in this step and it is carried out in the same reactor as the subsequent step 4. The catalyst (NiMo) used in step 4 is similar to the step 1 catalyst. Steps 3 and 4 carried out sequentially in the same reactor have similar operating conditions as shown in Table 5 below.
[0063] Olefin saturation and color adjustment occur in the final hydrofinishing step (4).
[0064] Table 5. Dewaxing (Step 3) and Hydrofinishing (Step 4) Operating Conditions
[0065]
[0066] *Based on total catalyst volume
[0067] The properties of the products from steps 3 and 4 are described in Table 6 below.
[0068] Table 6. Product Properties
[0069]
[0070] Example 2
[0071] In this example, base oil is prepared from commercially available TPO. The properties of the TPO used and the standard measurement methods employed are illustrated in Table 7 below. In this example, the TPO is subjected to a TPO distillation / fractionation step in the first step to obtain a TPO distillate. Then, in the second step, the TPO distillate is subjected to hydrotreating to obtain base oil. In the third step, the properties of the resulting base oil, especially the low-temperature properties, are further improved by subjecting the base oil to a dewaxing step. In the fourth step, the improved base oil from Step 3 is subjected to hydrofinishing. The objectives, method steps, and catalysts of Steps 2, 3, and 4 are the same as those in Example 1. However, the feed properties, operating conditions, and product properties are different. The details of the method will be further described below.
[0072] Table 7. TPO Properties
[0073]
[0074] Table 8. Hydrotreating (Step 2) Operating Conditions
[0075]
[0076] Table 9. Properties of the Liquid Product (Base Oil) from Step 2 (Hydrotreating)
[0077]
[0078]
[0079] As can be seen from the comparison of Tables 7 and 9, the high acidity of the TPO used did not affect the resulting base oil. This indicates that base oil with an acceptable acidity can be obtained from TPO using the method of the present invention.
[0080] Table 10. Dewaxing and Hydrofinishing (Steps 3 and 4) Operating Conditions
[0081]
[0082] * Based on total catalyst volume
[0083] Table 11. Product Properties of the Improved Base Oil Obtained from Steps 3 and 4
[0084]
[0085] Evaluation of the base oil samples in Tables 4 and 9 showed an average biogenic carbon content of 50% according to ASTM D6866 and a PAH content of less than 10 ppm for 10 specific PAHs according to EN 16143.
[0086] The miscibility experiments confirm the miscibility of TPO with the different co-feeds listed and support the co-processing ability based on the chemical composition of the fluids and experience in conventional refining.
Claims
1. A method for preparing a base oil with a sulfur content not exceeding 1 wt% from tire pyrolysis oil, comprising the following steps: Subject the pyrolysis oil of the tire to a hydroprocessing step including a hydrotreating step to obtain a hydroprocessed pyrolysis oil of the tire, wherein the hydrotreating step is carried out at a pressure in the range of 50 - 170 bar, a temperature in the range of 290 - 370 °C and a liquid hourly space velocity in the range of 0.4 - 2.0 h -1 in the presence of a base metal catalyst; and Distilling the hydroprocessed tire pyrolysis oil obtained from the hydroprocessing step to obtain at least two fractions, wherein at least one fraction is a base oil.
2. A method for preparing a base oil with a sulfur content not exceeding 1 wt% from tire pyrolysis oil, comprising the following steps: Distilling the tire pyrolysis oil to obtain one or more fractions; and Subjecting the one or more fractions obtained from the distillation step to a hydroprocessing step comprising a hydrotreating step, wherein the hydrotreating step is carried out in the presence of a base metal catalyst at a pressure in the range of 50 - 170 bar, a temperature in the range of 290 - 370 °C and a liquid hourly space velocity in the range of 0.4 - 2.0 h -1 to obtain one or more hydroprocessed products, wherein at least one product is a base oil.
3. The method according to claim 1 or 2, wherein the hydroprocessing step further comprises a catalytic dewaxing step in the presence of a base metal catalyst.
4. The method according to claim 3, wherein the catalytic dewaxing step is carried out at a pressure in the range of 100 - 160 bar, a temperature in the range of 350 - 400 °C, and a LHSV in the range of 0.4 - 2.0 h -1 under the conditions as mentioned above.
5. The method according to any one of claims 1-4, wherein the hydroprocessing step further comprises a hydrorefining step.
6. The method according to any one of claims 1-5, wherein waste oil, used oil, pyrolytic plastic waste oil, crude oil, crude oil distillate, VGO or any combination thereof is provided as a co-feed to the method and is processed together with the tire pyrolysis oil.
7. The method according to any one of claims 1-6, wherein the catalyst used in the method is selected from base metal catalysts.
8. The method according to any one of claims 1-7, wherein the tire pyrolysis oil exhibits a biogenic carbon content of at least 1 wt% determined according to ASTM D6866 method.
9. The method according to any one of claims 1-7, wherein the tire pyrolysis oil exhibits a biogenic carbon content of at least 5 wt%, more preferably at least 10 wt%, and even more preferably at least 30 wt% determined according to ASTM D6866 method. Base oil having a sulfur content of not more than 1% by weight obtainable by the process of claim 8, characterized in that Exhibits a biogenic carbon content of at least 1 wt% determined according to ASTM D6866 method, a viscosity index (VI) not greater than 110 and is substantially oxygen-free.
11. The base oil according to claim 9, which has a biogenic carbon content of at least about 5 wt%, more preferably at least 10 wt%, and even more preferably at least 30 wt% determined according to ASTM D6866 method.
12. The base oil according to claim 10 or 11, which has a viscosity of 3-700 cSt at 40 °C.