CN110922289B - Decolorizer for recovering styrene from pyrolysis gasoline - Google Patents

Abstract

The invention provides a decoloring agent for recycling styrene from pyrolysis gasoline and a using method thereof. In order to solve the problems of incomplete decoloring effect and large environmental pollution of the conventional decoloring agent 1, the invention adopts components capable of rapidly reacting with chromogenic substances in styrene materials, and provides an efficient pollution-free decoloring agent. The decoloring agent comprises the following components in percentage by weight: 55-70% of cinnamaldehyde and derivatives thereof, 5-15% of nitroxide free radical polymerization inhibitor and 15-30% of solvent. The decoloring agent can be selectively combined with a chromogenic substance to generate a component with the boiling point larger than that of styrene, and then the component is removed by distillation.

Description

Decolorizer for recovering styrene from pyrolysis gasoline

technical field

The invention relates to a decolorizing agent for styrene, in particular to a decolorizing agent used in the refining process of recovering styrene from pyrolysis gasoline.

Background technique

Styrene is a monomer for synthetic rubber and plastics, and is one of the most important olefins. It is mainly used to produce styrene-butadiene rubber, polystyrene and foamed polystyrene; Engineering plastics, such as ABS resin obtained by copolymerization with acrylonitrile and butadiene; it is also one of the raw materials for the production of ion exchange resins and pharmaceuticals. In addition, styrene can also be used in industries such as pharmaceuticals, dyes, pesticides, and mineral processing.

In industry, 90% of styrene is produced through the production process of ethylbenzene dehydrogenation, and the other is the co-oxidation method of ethylbenzene and propylene. These two technologies are mature, the production process is stable, and the obtained styrene products do not have or rarely have the problem of unqualified chroma. In recent years, with the increasing scale of ethylene plants, there are more and more large and super-large ethylene plants in the world. Recovering styrene from the pyrolysis gasoline fraction, a by-product of the ethylene production process, can reduce the hydrogen consumption and energy consumption of pyrolysis gasoline hydrogenation, Styrene products with higher value can also be recovered to obtain better economic benefits. Therefore, more and more large-scale ethylene plants have installed pyrolysis gasoline plants. The composition of the pyrolysis gasoline obtained from the cracking of naphtha is complex and diverse, so the styrene obtained by extraction and recovery has a high chroma, which cannot meet the requirements of high-quality products and needs to be refined and decolorized.

The platinum-cobalt chromaticity (Pt-Co) of the pyrolysis gasoline fraction is greater than 500. After extractive distillation, solvent recovery and refined styrene rectification unit, the problem of styrene chromaticity cannot be solved, and the obtained pure styrene chromaticity is still above 10.

The traditional process uses white clay for decolorization, which consumes a large amount of white clay and is difficult to regenerate. The disposal of these used white clay brings serious environmental protection pressure. In addition, white clay decolorization is an exothermic reaction, which makes styrene easy to polymerize. Strong acidity, when dealing with the styrene-containing stream obtained from pyrolysis gasoline, it will cause styrene and other unsaturated compounds contained in it to polymerize, easily cause tower plugging, and cause a large amount of target substance loss.

U.S. Patents US3763615 and US3763015 disclose a method for decolorizing styrene recovered in pyrolysis gasoline by using nitric acid as a decolorizing agent and building a new decolorizing unit. According to its patent description, the decolorization effect of using sulfuric acid, phosphoric acid, potassium permanganate and maleic anhydride as the decolorizing agent is good, but because nitric acid, sulfuric acid and potassium permanganate are all strong oxidizing agents, their industrial applications exist. Significant disadvantages. These strong oxidants first lead to the occurrence of many side reactions, and the generated by-products are introduced into the final product, which affects the purity of the product; secondly, the use of strong oxidants brings huge environmental pressure, and thirdly, the decolorization process is complicated and requires a large investment in facilities.

Contents of the invention

The technical problem to be solved by the present invention is the technical problem that the decolorizing agent used in the process of recovering styrene from pyrolysis gasoline is complicated to use, the decolorizing efficiency is low, and it is easy to have side reactions with styrene. The advantage of side reactions.

An embodiment of the present invention provides a decolorizing agent for recovering styrene from pyrolysis gasoline, the decolorizing agent components include by weight percentage: 55% to 70% of cinnamaldehyde and/or cinnamaldehyde derivatives, 5% to 70% of nitrogen oxide radical polymerization inhibitor 15%, solvent 15-30%.

In some embodiments of the present invention, the derivatives of cinnamaldehyde are selected from -NR ₃ , -F, -Cl, -Br, -I, -NO ₂ , -CN, -COOH, -C=O, -OCH ₃ , -C ₆ H ₅ group substituted cinnamaldehyde.

In some embodiments of the present invention, the amount of cinnamaldehyde used in weight percentage is not less than 10%.

In some embodiments of the present invention, the amount of cinnamaldehyde derivatives used is not less than 10% by weight.

In some embodiments of the present invention, the nitroxide radical polymerization inhibitor is a phosphorous acid (4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide radical) mixed ester.

In some embodiments of the present invention, the solvent is an aromatic hydrocarbon solvent with a high boiling point.

In some embodiments of the present invention, the distillation range of the aromatic hydrocarbon solvent is 188-206°C.

In some embodiments of the present invention, the weight ratio of the cinnamaldehyde to the cinnamaldehyde derivative is 1-3:1.

The decolorizing agent in the present invention is used for the decolorization of materials in the styrene extraction process.

The pyrolysis gasoline involved in the present invention mainly uses naphtha or light diesel oil as a by-product of steam cracking to produce ethylene, which contains a large amount of unsaturated hydrocarbons, and some of the unsaturated hydrocarbons are hydrocarbons with conjugated unsaturated bonds. Under the influence of conjugated unsaturated bonds, this kind of compound can absorb light in a specific wavelength range to develop color, and make the styrene recovered from pyrolysis gasoline appear yellow. To decolorize yellow styrene, it is necessary to remove this kind of conjugated Hydrocarbons with unsaturated bonds. Due to the special structure of the conjugated unsaturated bond, it can act as a dienite and undergo a Diels-Alder reaction with a decolorizing agent as a dienophile to generate a compound with a higher boiling point than styrene, and then these compounds can be purified by distillation. The resulting compounds are removed to obtain styrene with the required color. Styrene has strong activity, and it is easy to have a polymerization reaction with the decolorizing agent, resulting in a high polymer content in the styrene product, and the generated polymer is easy to accumulate on the inner wall of the material pipeline to form scale, which in turn blocks the material system, and in severe cases causes Parking; the nitroxide free radical polymerization inhibitor selected in the present invention can effectively prevent the polymerization reaction of styrene and decolorizer, and itself is a stable free radical, which can quickly eliminate free radicals in the medium and inhibit macromolecular polymerization The generation of things.

The method of using the decolorizing agent of the present invention is simple, and it can be directly injected into the styrene material pipeline through the injection system during use. The decolorizing agent directly reacts with the color-developing substance during the progress of the styrene material along with the styrene, and the reaction product can be obtained by distillation. A product whose chromaticity meets the requirements is obtained without additional devices, and the process is simple.

The decolorizer of the present invention has very strong selectivity in the Diels-Alder reaction with the chromogenic substance in the styrene-containing stream. Compared with other dienophiles such as maleic anhydride, cinnamaldehyde and its derivatives are relatively It is difficult to have a side reaction with styrene, and because of the presence of a polymerization inhibitor, it hardly reacts with styrene, which will neither cause the loss of styrene materials nor block the pipeline due to polymerization scaling; in summary As mentioned above, the decolorizing agent provided by the present invention has a wider scope of application and has achieved remarkable technical effects.

Detailed ways

In order to deepen the understanding of the present invention, the scale inhibitor of the present invention will be described in detail below in conjunction with the examples, but this does not constitute a limitation to the protection scope of the present invention; the present invention will be further illustrated by the examples below.

Example 1

The crude styrene recovered by extraction and rectification is taken from the styrene extraction device, and its color is about 500 as measured by the Pt/Co method, and the styrene content is 80-99%, ethylbenzene, p-xylene, The content of m-xylene, o-xylene, dicyclopentadiene and a small amount of C9 and above components is 8-12%. Get above-mentioned crude styrene of 500g, add decolorizing agent 5g of the present invention, wherein decolorizing agent is by weight 65% cinnamaldehyde, 10% cinnamon-COOH derivative, 5% phosphorous acid (4-hydroxyl-2,2,6 , 6-tetramethylpiperidine nitroxide radical) mixed ester, 20% aromatic solvent S-1500, fully stirred for 2 hours at normal temperature and pressure, the chromaticity was 4 in terms of platinum-cobalt units, and the calculated recovery rate of styrene was 97%.

Example 2

The raw material to be decolorized and the implementation steps are the same as in Example 1, get the above-mentioned crude styrene of 500g, add decolorizing agent 5g of the present invention, wherein decolorizing agent is 25% cinnamaldehyde, 30% cinnamaldehyde-COOH derivative, 15% by weight % Phosphorous acid (4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide free radical) mixed ester, 30% aromatic hydrocarbon solvent S-1500, fully stirred for 2 hours at normal temperature and pressure, the chromaticity is measured by platinum cobalt The unit is counted as 9, and the recovery rate of styrene is calculated to be 99%.

Example 3

The raw material to be decolorized and the implementation steps are the same as in Example 1, get the above-mentioned crude styrene of 500g, add decolorizing agent 15g of the present invention, wherein decolorizing agent is by weight 35% cinnamaldehyde, 30% cinnamaldehyde- _NO Derivatives, 10% phosphorous acid (4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide free radical) mixed ester, 15% aromatic hydrocarbon solvent S-1500, fully stirred for 2 hours at normal temperature and pressure, and the chromaticity was measured by platinum The cobalt unit is 7, and the recovery rate of styrene is calculated to be 98%.

Example 4

The raw materials to be decolorized and the implementation steps are the same as in Example 1. Get 500g of the above-mentioned crude styrene and add 10g of the decolorizing agent of the present invention, wherein the decolorizing agent is by weight cinnamaldehyde-NO ₂ , each 35% of the -COOH derivative, 10 % Phosphorous acid (4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide free radical) mixed ester, 20% aromatic hydrocarbon solvent S-1500, fully stirred for 2 hours at normal temperature and pressure, the chromaticity is measured by platinum cobalt The unit is counted as 4, and the recovery rate of styrene is calculated to be 99%.

Example 5

The raw material to be decolorized and the implementation steps are the same as in Example 1, get the above-mentioned crude styrene of 500g, add the decolorizing agent 5g of the present invention, wherein the decolorizing agent is 25% cinnamaldehyde, 45% cinnamaldehyde-CN derivative, 15% by weight % Phosphorous acid (4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide free radical) mixed ester, 15% aromatic hydrocarbon solvent S-1500, fully stirred for 2 hours at normal temperature and pressure, the chromaticity is measured by platinum cobalt The unit is counted as 4, and the recovery rate of styrene is calculated to be 99%.

Example 6

Naphtha is used as raw material for steam cracking, and the composition percentage of the C8 fraction of cracked gasoline obtained is: 30% styrene, 12% ethylbenzene, 5% xylene, and the rest is non-aromatic, and its color is determined by the Pt/Co method for 300. Get the above-mentioned pyrolysis gasoline fraction of 500g, add decolorizing agent 5g of the present invention, wherein decolorizing agent is by weight 45% cinnamaldehyde, 30% cinnamaldehyde-C=O derivative, 10% phosphorous acid (4-hydroxyl-2 , 2,6,6-tetramethylpiperidine nitroxide radical) mixed ester, 15% aromatic hydrocarbon solvent S-1500, fully stirred at room temperature and pressure for 2 hours, the chromaticity is 7 in terms of platinum cobalt unit, and styrene The recovery rate is 98%.

Example 7

The raw material to be decolorized and the implementation steps are the same as in Example 6, get 500g of the above-mentioned pyrolysis gasoline fraction, add 10g of the decolorizing agent of the present invention, wherein the decolorizing agent is derived from 10% cinnamaldehyde, 50% cinnamaldehyde-C=O by weight 10% phosphorous acid (4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide radical) mixed ester, 30% aromatic hydrocarbon solvent S-1500, fully stirred at room temperature and pressure for 2h, the color Calculated as 6 in platinum-cobalt units, the calculation shows that the recovery rate of styrene is 98%.

Example 8

The raw material to be decolorized and the implementation steps are the same as in Example 6, get 500g of the above-mentioned pyrolysis gasoline fraction, add 5g of the decolorizing agent of the present invention, wherein the decolorizing agent is derived from 25% cinnamaldehyde, 40% cinnamaldehyde-C=O by weight 15% phosphorous acid (4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide free radical) mixed ester, 20% aromatic solvent S-1500, fully stirred at room temperature and pressure for 2h, the color Calculated as 3 in platinum-cobalt units, calculations show that the recovery rate of styrene is 97%.

Example 9

The raw material to be decolorized and the implementation steps are the same as in Example 6. Get 500g of the above-mentioned pyrolysis gasoline cuts and add 5g of the decolorizing agent of the present invention, wherein the decolorizing agent is derived from 15% cinnamaldehyde and 50% cinnamaldehyde-C=O by weight. 15% phosphorous acid (4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide radical) mixed ester, 20% aromatic hydrocarbon solvent S-1500, fully stirred at room temperature and pressure for 2h, the color Calculated as 5 in platinum-cobalt units, the calculation shows that the recovery rate of styrene is 99%.

Example 10

The raw material to be decolorized and the implementation steps are the same as in Example 6, get 500g of the above-mentioned pyrolysis gasoline fraction, add 5g of the decolorizing agent of the present invention, wherein the decolorizing agent is derived from 50% cinnamaldehyde, 10% cinnamaldehyde-C=O by weight 10% phosphorous acid (4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide radical) mixed ester, 30% aromatic hydrocarbon solvent S-1500, fully stirred at room temperature and pressure for 2h, the color Calculated as 6 in platinum-cobalt units, the calculation shows that the recovery rate of styrene is 98%.

Claims (4)

1. The decoloring agent for recycling styrene from pyrolysis gasoline is characterized by comprising the following components in percentage by weight: 55-70% of cinnamyl aldehyde and cinnamyl aldehyde derivatives, 5-15% of nitroxide free radical polymerization inhibitor and 15-30% of solvent; the cinnamaldehyde derivative is selected from quilt-NR ₃ ，-F，-Cl，-Br，-I，-NO ₂ ，-CN，-COOH，-C=O，-OCH ₃ ，-C ₆ H ₅ Cinnamaldehyde substituted by a group; the cinnamaldehyde dosage in weight percent is not less than 10%; the amount of the cinnamaldehyde derivative is not less than 10% by weight; the nitroxide radical polymerization inhibitor adopts phosphorous acid (4-hydroxy-2, 6-tetramethyl piperidine nitroxide radical) mixed ester; the weight ratio of the cinnamyl aldehyde to the cinnamyl aldehyde derivative is 1-3:1.

2. The decolorizer according to claim 1, wherein the solvent is an aromatic hydrocarbon solvent having a high boiling point.

3. The decolorizer according to claim 2, wherein the aromatic solvent has a distillation range of 188 to 206 ℃.

4. The decolorizer according to any one of claims 1 to 3, which is used for decolorization of materials in a styrene extraction process.