Composite additive for modifying ethylene tar and preparation method thereof

Abstract

The invention provides a composite additive for modifying ethylene tar and a preparation method of the composite additive. The invention relates to a composite additive for modifying ethylene tar. The composite additive comprises the following components in parts by weight: 2-5 parts of nonylphenol polyoxyethylene ether, 2-5 parts of polyisobutylene succinimide, 1 part of hindered phenol antioxidant and 15-88 parts of heavy aromatic solvent oil. Three functional components, namely nonylphenol polyoxyethylene ether serving as a permeation disintegration type coupling agent, polyisobutylene succinimide serving as a steric hindrance type dispersing agent and hindered phenol antioxidant serving as a chemical stabilizer, are compounded to form a synergistic mechanism of physical dispersion and chemical passivation, so that the problems of high viscosity and instability of ethylene tar are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to a composite additive for ethylene tar, in particular to a composite additive for ethylene tar modification and a preparation method thereof, and belongs to the technical field of deep processing of chemical products. BACKGROUND

[0002] Ethylene tar is a liquid by-product produced by condensation and polymerization of raw materials and products at high temperature during the production of low-carbon olefins such as ethylene by steam cracking of hydrocarbons. Its yield accounts for more than 10% of the total feed amount of the ethylene plant, and the output is huge. Ethylene tar is rich in aromatic hydrocarbon compounds such as benzene, naphthalene and anthracene, and has potential utilization value.

[0003] However, ethylene tar itself has several inherent defects, which seriously restrict its high-value utilization. First, ethylene tar is a complex colloid system, in which asphaltene molecules act as a colloid nucleus and are dispersed in aromatic hydrocarbon solvents under the stabilizing action of resin molecules. This colloid structure results in extremely high viscosity at room temperature, with a kinematic viscosity of 40-50 mm 2 / s at 40℃, poor flowability, and great difficulty in pumping, conveying and atomization. Second, ethylene tar has poor chemical stability, and contains a certain amount of unsaturated compounds such as olefins, acetylenes and conjugated dienes. These active components are prone to free radical chain reactions such as self-polymerization and condensation during storage or heating, generating secondary resins and asphaltenes with larger molecular weight, resulting in further increase in viscosity, and even forming insoluble precipitates or coke, causing serious coking and plugging problems in heat exchangers, furnace tubes or fractionating columns.

[0004] At present, the most common way of using ethylene tar is to burn it directly as low-quality fuel oil, but this not only has low heat value, incomplete combustion and easy pollution of the environment by black smoke, but also has poor compatibility with other oil products, which can cause stratification and precipitation when mixed, affecting the stable operation of the boiler. In order to improve its value, some technologies propose to separate the light fuel oil components from it by vacuum distillation. For this purpose, an additive needs to be added for pre-modification. The modification scheme in the prior art can only solve the problem of aggregation of asphaltenes from a physical point of view, but ignores the self-polymerization reaction of unsaturated components that leads to instability of the system. Therefore, the modified ethylene tar will still generate secondary resins during subsequent heating, causing equipment coking, and the modification effect cannot be sustained. SUMMARY

[0005] Based on the above background, the purpose of the present application is to provide a composite additive for ethylene tar modification and a preparation method thereof, which has a significant and lasting modification effect on ethylene tar.

[0006] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical solutions:

[0007] A composite additive for ethylene tar modification comprises the following components in parts by weight: 2-5 parts nonylphenol polyoxyethylene ether, 2-5 parts polyisobutylene succinimide, 1 part hindered phenolic antioxidant, and 15-88 parts heavy aromatic solvent oil.

[0008] Preferably, the degree of polymerization of the polyoxyethylene in the nonylphenol polyoxyethylene ether is 8-12.

[0009] Preferably, the polyisobutylene succinimide is prepared from polyisobutylene with a molecular weight of 950-1300 Daltons.

[0010] Preferably, the hindered phenolic antioxidant is 2,6-di-tert-butyl-p-cresol or pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid].

[0011] Preferably, the nonylphenol polyoxyethylene ether is in the form of 4 parts by weight, and the polyisobutylene succinimide is in the form of 4 parts by weight.

[0012] A method for preparing a composite additive for ethylene tar upgrading as described above, the method comprising the following steps:

[0013] S1. Preparation of dispersant pre-concentrated solution: In the main reaction vessel, add 70-80% of the total amount of heavy aromatic solvent oil, heat to 70-90℃, then add the total amount of polyisobutylene succinimide, and stir until completely dissolved.

[0014] S2. Preparation of active micelle pre-concentrated solution: In the auxiliary reaction vessel, add the remaining 20-30% of heavy aromatic solvent oil and all the metered hindered phenolic antioxidants, stir to dissolve, and then add all the metered nonylphenol polyoxyethylene ether at 40-50℃, and stir to form active micelles encapsulating the hindered phenolic antioxidants.

[0015] S3, High-shear microemulsion fusion: Start the high-shear homogenizer in the main reactor and slowly inject the active micelle pre-concentrate prepared in step S2 into the main reactor under high-speed shear to fuse with the dispersant pre-concentrate;

[0016] S4. Homogenization: After injection, continue high-shear homogenization for 15-30 minutes to obtain the composite additive.

[0017] Preferably, in step S3, the rotation speed of the high-shear homogenizer is 5000-8000 rpm.

[0018] Preferably, in step S3, the injection time of the active micelle pre-concentrated solution is 10-20 minutes.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] The complex additive for ethylene tar modification and the preparation method thereof provided by the present application are prepared by compounding the three functional components of a penetration disintegration coupling agent nonylphenol polyoxyethylene ether, a steric hindrance dispersant polyisobutylene succinimide and a chemical stabilizer hindered phenolic antioxidant. The coupling agent and the dispersant synergistically act to disintegrate and stably disperse asphaltene colloidal particles from the physical level, and at the same time, the chemical stabilizer captures active free radicals from the chemical level to terminate the self-polymerization reaction of unsaturated hydrocarbons, thereby forming a synergistic mechanism of physical dispersion and chemical passivation, solving the problems of high viscosity and instability of ethylene tar. Since the physical aggregation and chemical reaction are simultaneously inhibited, the complex additive provided by the present application not only can greatly reduce the viscosity of ethylene tar, but also greatly improves the thermal stability and storage stability thereof, and can effectively inhibit the generation of secondary colloid and coke in the subsequent long-term storage or heating rectification process, thereby ensuring the persistence of the modification effect. DETAILED DESCRIPTION

[0021] The technical solutions of the present application are further specifically described below through specific examples. It should be understood that the implementation of the present application is not limited to the following examples, and any form of variation and / or change made to the present application will fall within the scope of protection of the present application.

[0022] In the present application, unless specified, all parts, percentages are weight units, and the equipment and raw materials used can be purchased from the market or are commonly used in the art. The methods in the following examples are all conventional methods in the art, unless otherwise specified. The components or equipment in the following examples are all general standard components or components known to those skilled in the art, and their structure and principle can be known to those skilled in the art through technical manuals or through conventional experimental methods.

[0023] Example 1

[0024] The present example provides a complex additive for ethylene tar modification and a preparation method thereof. The components of the complex additive are as follows (in parts by weight):

[0025] Nonylphenol polyoxyethylene ether (EO polymerization degree is 10): 4 parts

[0026] Polyisobutylene succinimide (prepared from polyisobutylene with a molecular weight of 1000): 4 parts

[0027] 2,6-Di-tert-butyl-p-cresol (BHT): 1 part

[0028] Heavy aromatic solvent oil (S-150): 45 parts

[0029] The preparation method of the complex additive is a stepwise microemulsion-high shear fusion method, and the specific steps are as follows:

[0030] S1, in the main reactor with high shear homogenizer, add 36 parts (80% of the total solvent) of heavy aromatic solvent oil, start stirring, heat to 80℃. Slowly add 4 parts of polyisobutylene succinimide, continue stirring for 30 minutes until completely dissolved, form a uniform transparent viscous solution, get the dispersant pre-concentrate.

[0031] S2, in a 250 mL side reactor, add 9 parts (20% of the total solvent) of heavy aromatic solvent oil and 1 part of BHT, stir to dissolve. Then control the temperature at 45℃, slowly add 4 parts of nonylphenol polyoxyethylene ether, continue stirring for 20 minutes, form active micelle pre-concentrate wrapped with BHT.

[0032] S3, start the high shear homogenizer of the main reactor, control the speed at 6000 rpm. The active micelle pre-concentrate in the side reactor is slowly injected into the main reactor under high shear by peristaltic pump within 15 minutes.

[0033] S4, after injection, continue high shear homogenization for 20 minutes, then cool down and discharge, get the transparent and uniform light yellow composite additive finished product.

[0034] Example 2

[0035] This example provides a composite additive for ethylene tar modification and its preparation method. The weight parts of the components of the composite additive are:

[0036] Nonylphenol polyoxyethylene ether (EO polymerization degree is 8): 2 parts

[0037] Polyisobutylene succinimide (prepared from polyisobutylene with a molecular weight of 950): 5 parts

[0038] Tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol ester (antioxidant 1010): 1 part

[0039] Heavy aromatic solvent oil (S-150): 24 parts

[0040] The preparation method of the composite additive is the same as example 1, the difference is:

[0041] S1, add 18 parts (75% of the total solvent) of heavy aromatic solvent oil in the main reactor, heat to 70℃, add 5 parts of polyisobutylene succinimide.

[0042] S2, in the side reactor, add 6 parts (25% of the total solvent) of heavy aromatic solvent oil, 1 part of antioxidant 1010 and 2 parts of nonylphenol polyoxyethylene ether, prepare active micelle pre-concentrate II at 40℃.

[0043] S3, the speed of high shear homogenizer is 5000 rpm, the injection time is 10 minutes.

[0044] S4, homogenization for 15 minutes.

[0045] Example 3

[0046] This example provides a composite additive for ethylene tar modification and a preparation method thereof. The weight parts of the components of the composite additive are as follows:

[0047] Nonylphenol polyoxyethylene ether (EO polymerization degree is 12): 5 parts

[0048] Polyisobutylene succinimide (prepared from polyisobutylene with a molecular weight of 1300): 2 parts

[0049] 2,6-di-tert-butyl-p-cresol (BHT): 1 part

[0050] Heavy aromatic solvent oil (S-150): 64 parts

[0051] The preparation method of the composite additive is the same as that of Example 1, except that:

[0052] S1, 51.2 parts (80% of the total solvent) of heavy aromatic solvent oil are added to the main reaction kettle, heated to 90°C, and 2 parts of polyisobutylene succinimide are added.

[0053] S2, 12.8 parts (20% of the total solvent) of heavy aromatic solvent oil, 1 part of BHT and 5 parts of nonylphenol polyoxyethylene ether are added to the auxiliary reaction kettle to prepare an active micelle pre-concentrate at 50°C.

[0054] S3, the high shear homogenizer speed is 8000 rpm, and the injection time is 20 minutes.

[0055] S4, homogenization for 30 minutes.

[0056] Comparative Example 1

[0057] The weight parts of the components of the composite additive are as follows:

[0058] Nonylphenol polyoxyethylene ether 4 parts, polyisobutylene succinimide 4 parts, heavy aromatic solvent oil 36 parts.

[0059] The preparation method is simple physical mixing.

[0060] Comparative Example 2

[0061] The weight parts of the components of the composite additive are as follows:

[0062] Polyisobutylene succinimide 4 parts, BHT 1 part, heavy aromatic solvent oil 20 parts.

[0063] The preparation method is simple physical mixing.

[0064] Comparative Example 3

[0065] The weight parts of the components of the composite additive are as follows:

[0066] Nonylphenol polyoxyethylene ether 4 parts, BHT 1 part, heavy aromatic solvent oil 20 parts.

[0067] The preparation method is simple physical mixing.

[0068] Comparative Example 4

[0069] The components of the composite additive are the same as in Example 1.

[0070] The preparation method is simple physical mixing, i.e. nonylphenol polyoxyethylene ether 4 parts, polyisobutylene succinimide 4 parts, BHT 1 part, and heavy aromatic solvent oil 45 parts are added at one time into a reaction kettle, and stirred at 60°C for 1 hour.

[0071] Take ethylene tar produced by a petrochemical enterprise as is (kinematic viscosity at 50°C is 48.5 mm 2 / s), respectively add 1.0% (by weight) of the additives prepared in Examples 1-3 and Comparative Examples 1-4, stir at 60°C for 30 minutes to make them fully mixed, and then perform performance testing. The test results are shown in Table 1.

[0072] Table 1: Performance comparison test results of composite additives

[0073] Sample No. 50 °C kinematic viscosity (mm 2 / s) Viscosity reduction rate (%) Kinematic viscosity at 50°C (mm 2 / s) after aging Viscosity change rate (%) Ethylene tar as is 48.5 - 102.3 110.9 Example 1 23.8 50.9 25.1 5.5 Example 2 25.2 48.0 26.8 6.3 Example 3 24.5 49.5 26.0 6.1 Comparative Example 1 24.1 50.3 45.6 89.2 Comparative Example 2 39.8 17.9 65.2 63.8 Comparative Example 3 25.5 47.4 88.9 248.6 Comparative Example 4 28.6 41.0 35.5 24.1

[0074] As can be seen from Table 1, the additives prepared in Examples 1-3 can all greatly reduce the viscosity of the ethylene tar, and the viscosity reduction rate reaches about 50%; more importantly, after the severe accelerated aging test, the viscosity only has a very small increase (the viscosity change rate is only 5.5%-6.3%), while the viscosity of the as-is sample increases by more than 100%. This proves that the composite additive of the present application has excellent viscosity reduction capacity and outstanding thermal stability.

[0075] Comparative Example 1 lacks a chemical stabilizer, although its initial viscosity reduction rate is comparable to that of Example 1, but after aging, its viscosity increases sharply, and the viscosity change rate is as high as 89.2%. This proves that the addition of a chemical stabilizer (a hindered phenolic antioxidant) plays an indispensable role in inhibiting the secondary polymerization of ethylene tar under heat conditions and maintaining its long-term stability.

[0076] Comparative Example 2 lacks a coupling agent, and its viscosity reduction rate is only 17.9%, indicating that it cannot effectively disperse asphaltene colloids. Comparative Example 3 lacks a dispersant, although the initial viscosity reduction rate is acceptable, but after aging, the viscosity increases sharply, and the viscosity change rate is as high as 248.6%, indicating that the dispersed asphaltene particles have undergone severe secondary aggregation. This proves that the coupling agent and the dispersant must exist together to achieve effective physical modification of first dispersion and then stabilization.

[0077] Comparative Example 4 is identical to Example 1 in terms of components and proportions, the only difference is the preparation method. Comparative Example 4 uses simple physical mixing, and its viscosity reduction rate (41.0%) and viscosity change rate (24.1%) are significantly worse than Example 1 which uses the stepwise microemulsion-high shear fusion method of the present application. This proves that the specific preparation method of the present application is not simply mixing, but through the construction of a specific microstructure, the synergistic effect between components is maximized, thereby bringing unexpected technical effects.

[0078] In summary, the present application is prepared by compounding specific three functional components and using a unique stepwise microemulsion-high shear fusion method. The resulting composite additive can efficiently modify ethylene tar from both physical and chemical dimensions, and has excellent and lasting viscosity reduction and stabilization effects.

[0079] The principles and implementation modes of the present application are described by applying specific examples in this paper, and the above examples are only used to help understand the method of the present application and its core idea. It should be pointed out that for ordinary skilled persons in the technical field, some improvements and modifications can be made to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A composite additive for ethylene tar upgrading, characterized in that: The composite additive comprises the following components in parts by weight: 2-5 parts nonylphenol polyoxyethylene ether, 2-5 parts polyisobutylene succinimide, 1 part hindered phenolic antioxidant, and 15-88 parts heavy aromatic solvent oil.

2. The composite additive for ethylene tar upgrading according to claim 1, characterized in that: The degree of polymerization of the polyoxyethylene in the nonylphenol polyoxyethylene ether is 8-12.

3. The composite additive for ethylene tar upgrading according to claim 1, characterized in that: The polyisobutylene succinimide is prepared from polyisobutylene with a molecular weight of 950-1300 Daltons.

4. The composite additive for ethylene tar upgrading according to claim 1, characterized in that: The hindered phenolic antioxidant is 2,6-di-tert-butyl-p-cresol or pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid].

5. The composite additive for ethylene tar upgrading according to claim 1, characterized in that: The nonylphenol polyoxyethylene ether is 4 parts by weight, and the polyisobutylene succinimide is 4 parts by weight.

6. A method for preparing a composite additive for ethylene tar upgrading as described in any one of claims 1-5, characterized in that: The method includes the following steps: S1. Preparation of dispersant pre-concentrated solution: In the main reaction vessel, add 70-80% of the total amount of heavy aromatic solvent oil, heat to 70-90℃, then add the total amount of polyisobutylene succinimide, and stir until completely dissolved. S2. Preparation of active micelle pre-concentrated solution: In the auxiliary reaction vessel, add the remaining 20-30% of heavy aromatic solvent oil and all the metered hindered phenolic antioxidants, stir to dissolve, and then add all the metered nonylphenol polyoxyethylene ether at 40-50℃, and stir to form active micelles encapsulating the hindered phenolic antioxidants. S3, High-shear microemulsion fusion: Start the high-shear homogenizer in the main reactor and slowly inject the active micelle pre-concentrate prepared in step S2 into the main reactor under high-speed shear to fuse with the dispersant pre-concentrate; S4. Homogenization: After injection, continue high-shear homogenization for 15-30 minutes to obtain the composite additive.

7. The method for preparing a composite additive for ethylene tar upgrading according to claim 6, characterized in that: In step S3, the rotation speed of the high-shear homogenizer is 5000-8000 rpm.

8. The method for preparing a composite additive for ethylene tar upgrading according to claim 6, characterized in that: In step S3, the injection time of the active micelle pre-concentrated solution is 10-20 minutes.