Methods of inhibiting polymerisation of vinyl aromatic compounds during extractive distillation

FIELD: chemistry.

SUBSTANCE: method of inhibiting polymerisation of vinyl aromatic compounds during extractive distillation includes the following steps: a) providing a mixture containing styrene; b) adding one 2-sec-butyl-4,6-dinitrophenol (DNBP) inhibitor to the mixture; and c) performing extractive distillation of the mixture after step b) to of separate styrene; d) forming less than 200 ppmw of a polymer from the styrene.

EFFECT: minimum polymer formation.

5 cl, 1 tbl, 1 ex

 

This application claims the priority of provisional patent application U.S. 61/226628 from July 17, 2009, patent application U.S. No. 12/705937 from February 15, 2010, each of which is included in the description of the invention by reference in full.

The technical FIELD TO WHICH the INVENTION RELATES.

Styrene and related aromatic compounds are the building blocks of many types of industrial products, such as, for example, polymers and resins. Styrene can be obtained as a commercial chemical product by selection from a stream of hydrocarbons (for example, from a pyrolysis gasoline) or by dehydrogenation of ethylbenzene. Vinylaromatic compounds (e.g. styrene) are usually isolated from pyrolysis gasoline extraction distillation, in which vinylaromatic connection is typically exposed to elevated temperature and/or oxygen. Both these factors can initiate undesirable thermal or free-radical polymerization or oligomerization. Polymerization can lead to loss of product and often leads to clogging of the equipment used to allocate vinylaromatic compounds from a stream of hydrocarbons.

To reduce the risk of polymerization vinylaromatic compounds when released from a stream of hydrocarbon extractive distillation typically Prov is car Ried out under reduced pressure to minimize contact with oxygen and low temperature to minimize heat. However, even in the best case vinylaromatic connection in contact with small amounts of oxygen and heated to temperatures in the range of about 80°C-160°C in a period of time from several seconds to several hours. Thermal polymerization of styrene may occur by heating styrene monomers to a temperature of about 100°C. or higher for several minutes. In addition to the above mentioned interaction with oxygen and thermal effects vinylaromatic compounds can react with various impurities contained in the source of hydrocarbons, such as, for example, sulfur containing compounds and colored impurities that may cause undesired polymerization.

There are various ways to reduce the risk of polymerization vinylaromatic compounds, in particular styrene, by adding small amounts of inhibitor to purified or unpurified vinylaromatic connections. For example, for inhibiting polymerization vinylaromatic compounds during vacuum distillation used dinitrophenol (for example, 2,6-dinitro-and-cresol). Also for inhibiting polymerization vinylaromatic compounds in the absence of oxygen or under atmospheric pressure, used a combination of steric obstruction of phenol (e.g., dinitrophenol), it is interesting hydroxylamine and phenylenediamine. Similarly for inhibiting polymerization vinylaromatic compounds used a combination of dinitrophenol and free radical not containing nitroxyl. In addition, for inhibiting polymerization vinylaromatic compounds used a combination of 2-NITROPHENOL with acid.

Although these systems are quite effective inhibitors in the production and purification of styrene by traditional dehydrogenation of ethylbenzene, the applicants believe that these inhibitors are not suitable in the case of extractive distillation of styrene and other vinylaromatic connections from a source of hydrocarbons, such as pyrolysis gasoline. Therefore, new methods of inhibiting polymerization vinylaromatic compounds in the course of their separation from the stream of hydrocarbons. Recent advances in the development of technologies for extraction allow to obtain styrene from pyrolysis gasoline product from steam cracking of naphtha, gas oil and liquefied natural gas. New types of separation technologies include conditions of heat and contact with oxygen, which are important parameters that ensure the maintenance of styrene and other vinylaromatic compounds in neapolitanum condition. Below effective ways to solve these problems.

The INVENTION

<> This results in various embodiments, methods of inhibiting polymerization vinylaromatic compounds during extraction distillation. These methods include the following stages: a) preparation of a mixture containing at least one vinylaromatic connection, (b) adding to the mixture at least one dinitrophenol inhibitor and (C) carrying out the extraction distillation of the mixture after stage b) to allocate at least one vinylaromatic connection. In some embodiments, allocate one vinylaromatic connection. In other embodiments, this only vinylaromatic compound is styrene.

Features of the present invention have been described above in General terms for a better understanding of the subsequent detailed description. The following are additional features and benefits, which are further presented in the claims.

The IMPLEMENTATION of the INVENTION

In the following description summarizes some of the details, such as specific quantities, sizes, etc. necessary for a complete understanding of the disclosed here options. However, experts in this field will be obvious that the present invention can be implemented without these specific details. In many cases, details of such consideration and such they were excluded who, because they were not necessary for a full understanding of the present invention and known qualified specialists in the respective field.

While most used terms understandable to experts in this field, however, it should be borne in mind that unless it is specifically agreed that the terms should be interpreted in the sense which is accepted by specialists in this field. In cases where the expression could be understood as meaningless or completely meaningless, its definition should be taken from Webster's Dictionary Webster's Dictionary, 3rd Edition, 2009. Do not enter the definition and/or interpretation of other related or unrelated patent applications, patents and publications, unless specifically set forth in this description or introduction is necessary to preserve meaning.

Used here, the term "aromatic" refers to aromaticity, i.e. chemical property, which provides a stronger stabilization of the coupled-loop containing unsaturated communication, lone-electron pair or vacant orbitals than would be expected if only one pair. Aromaticity can also be viewed as a manifestation of cyclic delocalization and resonance stabilization. Usually it is believed that this effect is due to free electrons in cycles atoms, which are interconnected alternating ordinary and double bonds.

Used here, the term "aliphatic" refers to compounds with carbon atoms, which can be connected to each other in unbranched chains, branched chains or rings (in this case they are called alicyclic). They can connect ordinary bonds (alkanes), double bonds (alkenes) or triple bonds (alkynes).

Used herein, the term "polymer" refers equally to polymers vinylaromatic compounds, including dimers, trimers, and higher oligomers and polymers.

In addition to working examples, or where otherwise indicated, all numbers, determining the number of components used in all the examples, you can add the word "about".

Variants of the present description generally relate to methods of inhibiting thermal or free-radical polymerization vinylaromatic compounds during extraction distillation. In the methods of extraction distillation vinylaromatic connection can be in contact with oxygen at low concentrations and at high temperatures (about 80°C-160°C) for different periods of time. These conditions contribute to the initiation of the polymerization vinylaromatic compounds. As shown here, high concentrationcontrolled inhibitor can be minimized or substantially inhibit polymerizatio vinylaromatic compounds during extraction distillation under such conditions, when in the absence of inhibitor polymer can be formed within a few minutes. In some embodiments, the dinitrophenol is a 2-sec-butyl-4,6-dinitrophenol (buffen, DNBP), which one is used for inhibiting polymerization.

In various embodiments, the present description discloses methods of inhibiting polymerization vinylaromatic compounds during extraction distillation. These methods include stages: a) preparation of a mixture containing at least one vinylaromatic connection, (b) adding to the mixture of at least one inhibitor of dinitrophenol and (C) carrying out the extraction distillation of the mixture after stage b) to allocate at least one vinylaromatic connection. In some embodiments, at least one aromatic compound is a styrene. In other embodiments, when the extraction distillation allocate only one vinylaromatic connection. In still other embodiments, only vinylaromatic compound is styrene.

In various embodiments, the mixture also includes impurities, which should be separated vinylaromatic connection. Such impurities include, for example, aliphatic compounds, aromatic compounds, other vinylaromatic compounds, sulfur containing compounds, colored impurities and the x combinations.

Later styrene presented as an example vinylaromatic connection, which can be distinguished by the methods described in this invention. However, the person skilled in the art know that other vinylaromatic compounds can be distinguished by the usual experimental modification described herein options that meet the spirit and scope of the present description.

In other embodiments, the styrene can be distinguished from pyrolysis gasoline by methods described in U.S. patent 5849982 and 5877385, each of which is incorporated herein by reference in its entirety. Among the conclusions of these patents provides a method of obtaining the average fraction of pyrolysis gasoline, which after removal of octane and heptane contains approximately 25-35% of styrene. After selective hydrogenation to remove phenylacetylene conduct extractive distillation for the separation of styrene from the other components of the mixture. Styrene goes into the solvent, which is then fed to the column separation of the solvent to remove the solvent and extraction of styrene. The separated solvent is then returned to the extraction column distillation. During the excretion of styrene temperature can reach at least about 100°C for a long time, especially in the superheating systems and in the lower part of the column is xtraction distillation. In the absence of inhibitor in these conditions can be formed polymer and its accumulation will lead to a complete disruption of the entire system. In various embodiments, the extraction distillation is carried out at a temperature of at least about 100°C. In other embodiments, the extraction distillation is carried out at a temperature from about 80°to about 160°C.

Although dinitrophenol and related NITROPHENOL known in this field, applicants believe that, in this description for the first time shown that the use of these compounds in high concentrations leads to inhibition of the polymerisation conditions, usually implemented with extraction distillation. In various embodiments can be minimized or substantially inhibit polymerization vinylaromatic compounds with additives dinitrophenol or related NITROPHENOL to the flow of hydrocarbons to highlight vinylaromatic compounds from the stream. In various embodiments, the dinitrophenol is a 2-sec-butyl-4,6-dinitrophenol (DNBP). In other embodiments, the flow of hydrocarbons is a stream of pyrolysis gasoline.

In various embodiments, inhibit thermal polymerization. In other embodiments, inhibit free-radical polymerization.

In various embodiments, the concentration DNBF or other dinitrophenol inhibitors in the flow angle is avodarto determines the efficiency of inhibition of polymerization vinylaromatic compounds. For example, in the presented here options DNBF in high concentrations can significantly slow down the polymerization vinylaromatic compounds. Concentration DNBF and other dinitrophenol inhibitors described in the presented here options, considerably higher than the values typically used in other cases when it is necessary to inhibit the polymerization vinylaromatic compounds. In some embodiments described herein, the concentration of DNBF is at least about 10000 mass. ppm relative to at least one vinylaromatic connection. In other embodiments, the concentration DNBF is about 10000 mass. ppm to about 20,000 masses. ppm In the following embodiments, the concentration DNBF is about 10000 mass. ppm to about 15,000 masses. ppm, In some embodiments, the concentration DNBF approximately 14,000 masses. ppm

Experimental example

The following example is provided to further illustrate certain disclosed above options. For specialists in this field it is important that described in this example techniques offer the ultimate model for the practical application of the invention. In light of this description professionals should take into account that in these specific ways you can make many changes, which do not deviate from duhai scope of this invention, with the same or similar result.

In the following example, the analysis for polystyrene was performed using a modified version of ASTM methods D2121 by precipitation of the polymer from a mixture of styrene/reagent for extraction using methanol and then filtering and drying the precipitated polymer. The threshold sensitivity of the assay was 200 mass. ppm polymer.

Example 1. Model raw with dinitrophenol inhibitor, corresponding to the composition of the mixture in the bottom of the column extractive distillation of styrene was prepared by mixing 95% reagent for extraction with 5% of styrene, whether or not containing different doses DNBF, as shown in table 1. Table 1 shows the data obtained after heating 35 g of this mixture at a temperature of 120-160°C for 0-180 minutes. The mixture was heated in a durable sealed tube. Samples for time = 0 minutes was removed from the heating zone, as soon as the sample temperature reached the set temperature. Relative quantity formed by heating the polystyrene is shown by the color of the corresponding cell of the table.

Based on the above description, the person skilled in the art can easily establish the main characteristics of this invention and, without departing from its amnestie volume, to make various changes and modifications to adapt the description to the various applications and conditions. Described above are only illustrative and are not intended to limit the scope of the invention defined by the claims.

1. Method of inhibiting polymerization vinylaromatic compounds during extraction distillation, comprising the following stages:
a) preparation of a mixture which contains styrene;
b) introducing the mixture of one inhibitor 2-sec-butyl-4,6-dinitrophenol (DNBP); and
c) carrying out the extraction distillation of the mixture after stage b) for separating styrene;
d) education less than 200 mass. ppm polymer of styrene.

2. The method according to claim 1 in which the extractive distillation is carried out at a temperature of at least about 100°C.

3. The method according to claim 1 in which the extractive distillation is carried out at a temperature of about 80°C to 160°C.

4. The method according to claim 1, wherein using the extraction distillation to separate the styrene.

5. The method according to claim 1, in which the concentration dinitrophenol inhibitor is at least about 10000 mass. ppm relative to styrene.



 

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12 cl

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1 cl, 8 ex, 1 tbl

FIELD: chemistry.

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1 tbl, 2 dwg

FIELD: chemistry.

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3 cl, 1 tbl, 3 dwg

FIELD: chemistry.

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14 cl, 3 ex, 6 dwg

FIELD: process engineering.

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FIELD: chemistry.

SUBSTANCE: invention relates to method of reducing acidity of hydrocarbon raw material, which includes: (a) contact of hydrocarbon raw material, which contains organic acid, with phosphonium ionic liquid, non-mixable with hydrocarbon raw material, including tetrabutyl phosphonium methane sulfonate, with obtaining mixture, which contains hydrocarbon and said liquid; (b) separation of mixture with obtaining effluent, which contains hydrocarbon, and effluent, which contains phosphonium ionic liquid, containing organic acid. In addition, method includes contact of effluent, which contains ionic liquid, with regenerating solvent and separation of effluent, containing ionic liquid, from regenerating solvent with obtaining flow of extract, which contains organic acid, and flow of regenerated ionic liquid, which contains phosphonium ionic liquid, non-mixable with raw material, where regenerating solvent contains water, and flow of regenerated ionic liquid additionally contains water and where effluent, which contains hydrocarbon, contains phosphonium ionic liquid, non-mixable with raw material, additionally including washing of, at least, part of effluent, which contains hydrocarbon, with water with obtaining effluent, containing washed hydrocarbon, and flow of waste water, and flow of waste water contains phosphonium ionic liquid, non-mixable with raw material; with, at least, part of flow of waste water being, at least, part of regenerating solvent.

EFFECT: claimed method can ensure removal of up to eighty percent of organic acids from hydrocarbon.

10 cl, 2 dwg, 5 ex, 1 tbl

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