A method for recovering co-curing from heavy oil streams
By recovering cumulant from heavy oil streams through vacuum distillation and cooling crystallization, the problem of clogging in heavy oil streams was solved, high-purity cumulant was recovered, and economic value was enhanced.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2023-11-27
- Publication Date
- 2026-06-30
AI Technical Summary
Existing technologies are insufficient to effectively recover methyl sulfide from heavy oil streams, resulting in low content and purity. Furthermore, heavy oil streams are prone to solidification, causing pipeline blockages and impacting process operation and economic value.
Heavy oil streams were processed using vacuum distillation and cooling crystallization. Light components were removed by vacuum distillation, and the cooling rate was controlled to precipitate chelate crystals. The purity was improved by washing and recrystallization with different solvents.
It significantly improved the recovery rate and purity of the combined oil, solved the problem of clogging in heavy oil logistics, and enhanced its economic value.
Abstract
Description
Technical Field
[0001] This invention belongs to the field of cumene hydroperoxide recovery technology, and relates to a method for recovering cumene hydroperoxide from heavy oil streams, and more specifically to a method for treating heavy oil streams using a process employing cumene hydroperoxide and recovering cumene hydroperoxide therefrom. Background Technology
[0002] Cumene hydroperoxide (CHP) is a widely used oxidant. A typical example is the CHPPO process, which first oxidizes cumene to CHP, then uses it as an oxidant to oxidize propylene to produce propylene oxide (PO). During the oxidation of propylene, CHP itself is reduced to α,α-dimethylbenzyl alcohol. The CHPPO process usually hydrogenates benzyl alcohol back to cumene for recycling; however, due to side reactions, after recovering cumene, most of the dimethylbenzyl alcohol and cumene are lost, leaving a heavy oil stream containing numerous high-boiling-point and high-melting-point components. Bismuth subsalicylate (BDS) is a very small byproduct in this process. This heavy oil stream has a complex composition, mainly containing components such as acetophenone, phenol, α-methylbenzyl alcohol, 2-phenyl-1-propanol, propylene glycols (mainly dipropylene glycol), and BDS (2,3-dimethyl-2,3-diphenylbutane). The content of methyl benzoate is low, generally ranging from 1% to 25%, and sometimes not exceeding 10%. Furthermore, this heavy oil stream is prone to solidification at lower temperatures, often causing pipeline blockages, leading to operational difficulties and additional costs. Currently, incineration is the most common method of disposal. Therefore, in the complex composition of heavy oil streams, trace amounts of methyl benzoate are difficult to extract, separate, or reuse.
[0003] Lianku can be used as a flame retardant additive for polymer materials, and also as an initiator for polymer reactions such as crosslinking and grafting. It is widely used in the modification of various polymer materials such as polyolefins, polycarbonates, and polyethers. Compared with ordinary free radical initiators, Lianku has the advantage of a higher decomposition temperature (above 200℃), making it suitable for initiation reactions at high temperatures; at the same time, Lianku does not contain oxygen, which is beneficial to improving the final antioxidant and anti-aging capabilities of the treated polymer.
[0004] In existing technologies, cumene-3-ethylhexylene (CHP) is prepared via cumene and a free radical initiator. The free radical initiator used to produce CHP is typically an organic peroxide or an azo initiator. Therefore, in a process system where cumene and CHP are present simultaneously, CHP will naturally be generated. Due to safety requirements for peroxides, most such processes limit the maximum reaction and separation temperature to no more than 200°C. This is beneficial for the formation and stability of CHP, which ultimately enters the heavy oil stream and becomes an important component. However, due to the easily decomposable nature of CHP and the requirements of processes such as CHPPO, the heavy oil stream also includes byproducts of CHP decomposition, such as acetophenone. These components are also present in large quantities in the heavy oil, diluting the concentration of CHP.
[0005] The symmetrical molecular structure of methyl sulfide, with a melting point of 90–110°C, is a major cause of heavy oil solidification. If methyl sulfide can be separated from heavy oil, valuable products can be obtained while effectively improving the flowability of the remaining components, greatly avoiding or alleviating the problem of heavy oil solidification.
[0006] In summary, the main technical challenges in recovering cumulone from heavy oil are: 1) the cumulone content in heavy oil is low, resulting in limited recovery rates; and 2) heavy oil contains many impurities, affecting the purity of the recovered cumulone. Finding a suitable method for recovering cumulone from heavy oil streams has significant practical industrial implications. Summary of the Invention
[0007] To effectively recover cumene sulfide (CLS) and simultaneously address the problem of heavy oil stream blockage, this invention aims to provide a method for recovering CLS from heavy oil streams. This method is applicable to various processes using cumene hydrogen peroxide as an oxidant, effectively recovering most of the CLS from heavy oil and obtaining high-purity products, significantly improving economic value while resolving the problem of heavy oil stream blockage.
[0008] This invention provides a method for recovering methyl ester from a heavy oil stream. The method includes: subjecting the heavy oil stream to vacuum distillation, followed by cooling and crystallization to separate and obtain the recovered methyl ester.
[0009] According to the present invention, the method is applicable to processes using cumene hydrogen peroxide as an oxidant. The heavy oil stream is the heavy oil stream obtained after a process using cumene hydrogen peroxide as an oxidant (CHPPO). The process includes a step of hydrogenolysis and recovery of most of the cumene. In the heavy oil stream, the co-cumulone content is 0.5 wt% to 25 wt%, preferably 1 wt% to 15 wt%.
[0010] According to the present invention, in the method, the content of cumene in the heavy oil stream is further 0.01 wt% to 5 wt%; the content of acetophenone is 5 wt% to 50 wt%; the content of phenol is 1 wt% to 20 wt%; and the content of α-methylbenzyl alcohol is 0.1 wt% to 20 wt%.
[0011] According to the present invention, the vacuum distillation conditions in the method are: a pressure of 5–50 kPaA and a distillation temperature of 170–190 °C. The purpose of vacuum distillation is to remove components with a boiling point below 210 °C at atmospheric pressure. A key component is acetophenone, which is abundant in heavy oil and is a relatively good solvent; the presence of a certain amount of acetophenone will affect the recovery rate of the acetophenone. Distillation should be carried out under reduced pressure so that the distillation temperature can be below 200 °C to avoid the decomposition loss of the acetophenone. Vacuum distillation is preferably carried out in the bottom of a reaction column.
[0012] According to the present invention, in the method, a preferred embodiment is that the content of acetophenone in the bottom liquid after distillation is less than 5 wt%, and a more preferred embodiment is that the residual content of acetophenone is reduced to less than 0.5 wt%. In this case, other components that may affect the recovery rate and purity of the distillate, such as phenol, isopropylphenol, and 2-phenyl-1-propanol, can also be completely or partially removed. More preferably, the content of each of the above-mentioned substances (phenol, isopropylphenol, 2-phenyl-1-propanol, etc.) in the bottom liquid after distillation is less than 5 wt%.
[0013] According to the present invention, in the method, cooling the distilled liquid precipitates tannin crystals. However, rapid cooling often results in the inclusion of impurities in the product that are difficult to wash and remove. To reduce impurity inclusion and thus improve the purity of the precipitated crystals, the cooling operation is preferably carried out at a rate of 1°C / min or higher, preferably 1 to 2°C / min. More preferably, when the temperature is below 40°C, the cooling rate is 0.5°C / min or higher and less than 1°C / min. The temperature is lowered to -10 to 30°C. This cooling operation is beneficial for improving the yield of tannin.
[0014] According to the present invention, in the method, the separation can be filtration. The separated solid can be washed and / or dried. The washing temperature does not exceed the crystallization temperature. Preferably, the washing temperature is -10 to 30°C. The chelate crystals are washed using a first-class solvent, which is a polar solvent, preferably one or more of water, C1-C4 alcohols, nitriles, and halogenated hydrocarbons. More preferably, the washing solvent contains not less than 50 wt% methanol and / or ethanol. Low temperature and polar solvents are beneficial for reducing chelate loss and removing impurities. The drying temperature is 60 to 120°C, and the time is 1 to 12 hours.
[0015] According to the present invention, in the method, a product containing not less than 97 wt% methyl methacrylate (MMA) can be obtained after crystallization. The obtained MMA crystals are in a good needle-like or plate-like crystalline morphology. The mother liquor after crystallization mainly contains components such as propylene glycol, and has good fluidity at room temperature.
[0016] According to the present invention, recrystallization can be performed as needed in the method. The second type of solvent for recrystallization is a non-polar solvent, which can be selected from one or more of alkanes, cycloalkanes, and aromatics, preferably aromatics, and more preferably the solvent composition contains not less than 50 wt% cumene.
[0017] Compared with the prior art, the main advantages of this invention include:
[0018] In this invention, the inventors discovered that in the heavy oil stream of the CHPPO process, there are three main issues: first, the content of cumene hydroperoxide (CH2O) is low, making effective crystallization difficult; second, the small amount of acetophenone and other components in the heavy oil stream acts as an effective solvent for CH2O, and the presence of a certain amount of acetophenone affects the recovery rate of CH2O; and third, phenol or other components with high melting points solidify together with CH2O when cooled, affecting the purity of the solid product. Therefore, the recovery of CH2O from the heavy oil stream is ineffective. In this invention, firstly, light components with a boiling point below 210℃ at atmospheric pressure are removed by vacuum distillation, which greatly increases the concentration of CH2O in the heavy oil. The distilled light fraction can also be easily refined to obtain valuable products. The concentrated CH2O can crystallize out, and by controlling the crystallization rate to reduce impurities in the mother liquor, washing and recrystallizing with different solvents yields a high-purity CH2O product. This invention is applicable to various processes using cumene hydrogen peroxide as an oxidant, the characteristics of which dictate the inevitable presence of CH2O. To ensure a heavy oil stream that can be processed according to the method of this invention, the preferred process includes a step of hydrogenolysis to recover most of the cumene. After recovering the cumene, a stream containing various high-boiling-point components usually remains, which is the target of this invention. The method of this invention can effectively recover most of the cumene from heavy oil and obtain a high-purity product, significantly improving economic value. It also solves the problem of clogging in heavy oil streams. Detailed Implementation
[0019] In this invention, the purity of the product was analyzed by chromatography. The instrument used was an Agilent 7890 gas chromatograph with an InnoWax capillary column, nitrogen as the carrier gas, a vaporization chamber temperature of 250°C, a column oven temperature of 50–280°C, and a flame ionization detector.
[0020] Some preferred embodiments of the present invention are described in detail below. However, the specific parameters in the embodiments do not limit the scope of the claims made by the present invention.
[0021]
Example 1
[0022] The heavy oil sample from the CHPPO unit contained 21 wt% acetophenone, 11 wt% benzo[a], 4 wt% phenol, 5 wt% α-methylbenzyl alcohol, 0.7 wt% cumene, and the balance being other impurities.
[0023] A 2.5 kg sample was subjected to vacuum distillation under the following conditions: pressure 10 kPaA and reboiler temperature 180 °C. After distillation, the reboiler liquid contained: 0.9 wt% acetophenone, 0.4 wt% phenol, 0.3 wt% α-methylbenzyl alcohol, 0.01 wt% cumene, and 46 wt% bismuth substrate, with the remainder being other impurities.
[0024] The liquid from the bottom of the column was transferred to a flask heated in a water bath. The initial water bath temperature was 90°C, and no solid precipitation was observed. The flask was kept still, and the water bath temperature was gradually reduced to 40°C at a rate of 1°C / min, and then further reduced to 10°C at a rate of 0.5°C / min. A large amount of white, slightly transparent, flaky crystals precipitated out.
[0025] The crystals were filtered out of the mother liquor, washed with 100 mL of methanol at 5 °C, and then dried at 80 °C for 12 h after filtration.
[0026] The product weighed to obtain 197g, of which the content of methyl thiocyanate was 98.1wt%.
[0027] The product was subjected to secondary crystallization using a recrystallization solvent of 80 wt% cumene and 20 wt% cyclohexane, and the final product had a purity of 99.2 wt%.
[0028]
Example 2
[0029] The heavy oil sample obtained in the pilot study using CHP epoxidized butene contained 17 wt% acetophenone, 10.3 wt% benzo[a], 7.1 wt% phenol, 0.6 wt% α-methylbenzyl alcohol, 1.1 wt% cumene, and the balance being other impurities.
[0030] 500g of sample was subjected to vacuum distillation under the conditions of 8.0 kPaA and a reboiler temperature of 185℃. After distillation, the reboiler liquid contained: 1.1 wt% acetophenone, 0.9 wt% phenol, 0.1 wt% α-methylbenzyl alcohol, 0.02 wt% cumene, and 37.5 wt% bismuth substrate, with the balance being other impurities.
[0031] The liquid from the bottom of the column was transferred to a flask heated in a water bath. The water bath temperature was gradually reduced to 40°C at a rate of 1°C / min, and then further reduced to 10°C at a rate of 0.5°C / min. A light-colored solid precipitated out.
[0032] The crystals were filtered out of the mother liquor, washed with 25 mL of methanol at 5 °C, filtered, and dried at 80 °C for 12 h.
[0033] The product was subjected to secondary crystallization using cumene as a recrystallization solvent, and the final product had a purity of 99.3 wt%.
[0034] The product was weighed and found to be 18.7g.
[0035]
Example 3
[0036] The same 500g sample as in Example 1 was subjected to the same vacuum distillation procedure. The sample was then cooled to precipitate flaky crystals. The cooling parameters were the same as in Example 1.
[0037] The crystals were filtered out of the mother liquor, washed with 50 mL of a solvent containing 50 wt% ethanol and 50 wt% water at 5 °C, filtered, and dried at 80 °C for 12 h.
[0038] The product weighed to obtain 40.1g, of which the content of methyl thiocyanate was 97.0wt%.
[0039] The product was subjected to secondary crystallization using a recrystallization solvent of 80 wt% cumene and 20 wt% cyclohexane, and the final product had a purity of 99.0 wt%.
[0040]
Example 4
[0041] The same 500g sample from Example 1 was subjected to vacuum distillation under the following conditions: pressure 44.0 kPaA and reboiler temperature 190°C. After distillation, the reboiler liquid contained: 2.1 wt% acetophenone, 1.9 wt% phenol, 1.7 wt% α-methylbenzyl alcohol, 0.02 wt% cumene, and 41 wt% bismuth substrate, with the balance being other impurities.
[0042] The solid precipitated by cooling. The cooling procedure was the same as in Example 1. The crystals were filtered from the mother liquor, washed with 50 mL of methanol at 5°C, filtered again, and dried at 80°C for 12 h.
[0043] The product weighed to obtain 19.2g, of which the content of chloroquine was 98.3wt%.
[0044] The product was subjected to secondary crystallization using a recrystallization solvent of 80 wt% cumene and 20 wt% cyclohexane, and the final product had a purity of 99.3 wt%.
[0045] Comparative Example 1
[0046] The same 500g sample as in Example 1 was subjected to vacuum distillation under the following conditions: pressure 30 kPaA and reboiler temperature 160°C. The reboiler composition consisted of 6.1 wt% acetophenone, 3.3 wt% phenol, 2.6 wt% α-methylbenzyl alcohol, 0.02 wt% cumene, and 20 wt% methylbenzyl alcohol.
[0047] The cooling and washing steps were the same as in Example 1. The content of chloroquine was analyzed to be 51 wt%.
[0048] Recrystallization was performed using the same recrystallization solvent as in Example 1, and the final product had a purity of 77 wt%.
[0049] Comparative Example 2
[0050] The same 500g sample as in Example 1 was subjected to the same vacuum distillation operation.
[0051] The liquid in the column reboiler was rapidly placed in a refrigerator for cooling. The cooling rate was 3.8°C / min for the first 30 minutes, after which the temperature reached 65°C. After 30 minutes, the cooling rate was 1.5°C / min, and this rate was maintained to reduce the temperature to the same level as in Example 1.
[0052] In this case, a large number of dark, fine particles were precipitated.
[0053] The particles were filtered out of the mother liquor, washed with 100 mL of methanol at 5 °C, and dried at 80 °C for 12 h.
[0054] The product weighed to obtain 176g, of which the content of chloroquine was 81.8wt%.
[0055] The product was subjected to secondary crystallization using a recrystallization solvent of 80 wt% cumene and 20 wt% cyclohexane, and the final product had a purity of only 92 wt%.
[0056] Based on the results of the examples and comparative examples, removing acetophenone as much as possible is the key to the effective precipitation of acetophenone, while excessively rapid cooling is not conducive to ensuring the purity of the acetophenone product.
[0057] The specific embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.
Claims
1. A method for recovering dicyclopentadiene from a heavy oil stream comprising: The heavy oil stream is subjected to vacuum distillation, then cooled and crystallized to obtain the recovered cumulant. The conditions for vacuum distillation are: pressure of 5~50 kPaA and distillation temperature of 170~190℃; After distillation, the content of acetophenone in the bottom liquid of the column was less than 5 wt%. The cooling operation is carried out at a rate of 1℃ / min or higher; When the temperature is below 40℃, the cooling rate is greater than or equal to 0.5℃ / min and less than 1℃ / min; The heavy oil stream comes from the CHPPO process, which uses cumene hydrogen peroxide as an oxidant. In the heavy oil stream, the content of cumene is 0.5wt%~25wt%; the content of cumene is 0.01wt%~5wt%; the content of acetophenone is 5wt%~50wt%; the content of phenol is 1wt%~20wt%; and the content of α-methylbenzyl alcohol is 0.1wt%~20wt%.
2. The method of claim 1, wherein, The cooling operation is carried out at a rate of 1~2℃ / min.
3. The method of claim 1, wherein, The heavy oil stream contains 1 wt% to 15 wt% coke.
4. The method of claim 1, wherein, Lower the temperature to -10~30℃.
5. The method of claim 1, wherein, The washing temperature should not exceed the crystallization temperature.
6. The method of claim 5, wherein, The washing temperature is -10~30℃.
7. The method of claim 1 wherein, The precipitated chlorine crystals were washed with a polar solvent of type I.
8. The method according to claim 7, characterized in that, The first type of solvent is selected from one or more of the following: water, C1-C4 alcohols, nitriles, and halogenated hydrocarbons.
9. The method according to claim 1, characterized in that, After crystallization, recrystallization is carried out; the second type of solvent for recrystallization is a non-polar solvent, which is one or more of alkanes, cycloalkanes, and aromatics.