CS247496B1 - Process for the production of resins from heavy pyrolysis products - Google Patents

Abstract

A method for producing resins from heavy pyrolysis products by thermal and/or catalytic polymerization of a fraction of monomeric unsaturated hydrocarbons originating from pyrolysis and containing in particular indene and its homologues, homologues of styrene and other unsaturated hydrocarbons C9_jQ. The starting fraction for polymerization is a residue from the vacuum distillation of a fraction of pyrolysis gasoline, or a distillate from the vacuum distillation of pyrolysis oil, or a residue from the vacuum distillation of all pyrolysis gasoline.

Description

In the production of olefins by pyrolysis of hydrocarbons, in addition to the basic olefins Cj, there are also heavier, unsaturated or aromatic fractions. The unsaturated nature of these substances provides a basic prerequisite for their use in the production of resins. So-called gasoline resins are known, produced on the basis of olefins contained in the pyrolysis fraction Cg, or possibly also C _g _g. These gasoline resins can form a cheap, although not in all respects satisfactory component of coatings.

The pyrolysis fraction with a distillation range of approximately 45 to 190 to 200 °C is referred to as pyrolysis gasoline. It is usually processed by separating the Cg fraction by distillation, then the strongly aromatic _Cg to _Cg fraction /so-called BTX fraction/ from which aromatics are obtained and the remainder is the so-called Cg ₊ fraction. The Cg ₊ fraction is used as a component of motor fuels after hydrogenation to 1 or 11°, or as a solvent. The Cg ₊ fraction contains Cg and predominantly aromatic hydrocarbons.

A production process for utilizing heavier hydrocarbons from pyrolysis gasoline for the production of light resin with the trade name PYROLEN /product BLR/ is known. The basic hydrocarbon for this product is styrene and to a lesser extent Cg hydrocarbons. The disadvantage of this process is that it uses a relatively valuable raw material with a high styrene content, from which valuable benzene or toluene can be produced by various dealkylation processes after prior hydrogenation to I or II °C.

The heaviest pyrolysis product is the so-called pyrolysis oils, which are fractions boiling above 200 °C. Usually one pyrolysis oil is discarded, in some pyrolysis units it is possible to extract the lighter pyrolysis oil, the so-called gas pyrolysis oil, and the heavier pyrolysis oil, the so-called heating pyrolysis oil.

Compared to other pyrolysis products, pyrolysis oils are the least valuable products. The process of using pyrolysis oil for the production of resins is known, either by direct polymerization of pyrolysis oil or by atmospheric distillation separation of its lightest parts and polymerization.

In both cases, resins can be obtained, but their quality, especially in terms of dark to black color and lower softening point, is not satisfactory for use in coatings.

These resins can be used, for example, as a plasticizer in the rubber industry or as adhesives.

A method has now been found for producing resins from heavier fractions of pyrolysis gasoline or lighter fractions of pyrolysis oil. The method for producing resins from heavy products of pyrolysis of hydrocarbons and hydrocarbon fractions by thermal and/or catalytic polymerization of unsaturated hydrocarbons consists, according to the invention, in that a fraction from pyrolysis containing in particular indene and its homologues, homologues of styrene and other unsaturated hydrocarbons C _g to C ₁₀ , preferably a residue from the vacuum distillation of pyrolysis gasoline from a water wash of pyrolysis gasoline containing 35 to 40 wt. % indene and 14 to 16 wt. % methylstyrene, or a distillate from the vacuum distillation of pyrolysis gas oil containing 35 to 40 wt. % indene and 6 to 9 wt. % methylstyrene or the residue from the vacuum distillation of all pyrolysis gasoline after separation of the Cg-fraction containing 18 to 20 wt. % indene, 18 to 24 wt. % methylstyrene and 50 to 55 wt. % C _1Q homologues of indene and styrene.

The advantage of the process from the heavier fractions of pyrolysis gasoline is that the raw material is indene and its homologues and also the homologues of styrene Cg and C _1Q , but not styrene itself. The resin obtained is suitable for use in paints in terms of color. The advantage of the process from the lighter fractions of pyrolysis oil is that this way it is possible to evaluate the relatively least valuable product of pyrolysis and that, using a suitable technological process, it is also possible to produce light-colored resins, suitable for use in all paints, including varnishes.

The obtained resins are characterized by water resistance, unsaponifiable nature and a high softening point of around 100 ° C. In addition, due to their light color, these resins can replace expensive imported rosin.

The fraction of the desired composition suitable for polymerization can be obtained by distillation treatment of pyrolysis gasoline. A suitable fraction is the residue from vacuum distillation at a pressure of 3 to 40 kPa, a temperature at the bottom of the column up to 160 °C, preferably up to 130 °C, into which is introduced as a raw material a portion of pyrolysis gasoline, which is condensed in a pyrolysis gas water scrubber at a temperature at the top of 30 to 45 °C, at the bottom of 70 to 85 °C and a pressure of 0.03 to 0.08 MPa, while the pyrolysis gasoline obtained by primary distillation of pyrolysis products contains most of the indene contained in the pyrolysis products, preferably over 90% by weight, and a minimum content of naphthalene, preferably up to 1% by weight.

Or, the raw material for polymerization can be a distillate from vacuum distillation of pyrolysis gas oil at a pressure of 2 to 30 kPa, a temperature at the bottom of the column of up to 170 °C, preferably 140 °C with a naphthalene content of up to 10%, preferably 3%, and with a minimum temperature gradient in the column reboiler, with the temperature regime of primary distillation being controlled so that indene from the pyrolysis products enters the pyrolysis gas oil in an amount of over 50%.

Finally, the raw material for polymerization can be the residue from the vacuum distillation of all pyrolysis gasoline, from which the C^-fraction is separated by distillation and the residue is subjected to vacuum distillation at a pressure of 10 to 40 kPa, a temperature in the head of 75 to 95 °C, in the bottom of 140 to 170 °C with a minimum temperature gradient in the column reboiler.

The basis of the technological process for preparing raw materials for polymerization into resins is the prevention of oxygen access and gentle vacuum distillation with a low thermal load for a short dwell time during distillation and heating of the feed to a higher temperature, which should be as low as possible, but no more than 170 °C at the bottom of the column, and then a suitably selected mode of the so-called primary column, in which pyrolysis oils are separated so that the appropriate proportion of indene or methylindenes passes into the fraction from which the raw material for polymerization is obtained by subsequent rectification.

From pyrolysis gasoline, the raw material for polymerization is obtained as a vacuum residue. From pyrolysis oil, the raw material for polymerization is obtained as a vacuum distillate. Polymerization inhibitors can be added during distillation, but their effect is not decisive.

For the production of light resins, it is crucial that the monomer fraction for polymerization is light. This requirement can be met by vacuum distillation of pyrolysis oil under the above conditions, whereby the raw material for polymerization is obtained as a distillate that is not as thermally loaded as the distillation residue, nor is it colored by hydrocarbon compounds with oxygen, or sulfur and nitrogen, which are present in pyrolysis oil, albeit in traces, and accumulate in the residue during distillation.

In the case where the raw material for polymerization is obtained as a distillate from pyrolysis gas oil, the temperature regime of the primary column is controlled so that a larger proportion of indene remains in the pyrolysis oil. To verify the quality of the resins as a final product, polymerization tests were carried out in a conventional manner. However, the focus of the invention lies in the process for producing a suitable raw material for polymerization, from which resins can be economically produced by more or less known processes.

In the production process based on the above-described pyrolysis gasoline, the primary column regime is controlled in such a way that most of the indene contained in the pyrolysis products leaves the column overhead, but no naphthalene passes into the distillate, i.e. heavy pyrolysis gasoline. These requirements are achieved by a suitable choice of parameters affecting the temperature profile of the primary column, in particular the amount of reflux.

It was further found that it is advantageous not to start from the entire amount of pyrolysis gasoline, as is commonly done in pyrolysis units, but to start from the heaviest fraction of this pyrolysis gasoline. This is the fraction that condenses in the pyrolysis gas water scrubber at a temperature of 30 to 45 °C at the top, 70 to 85 °C at the bottom and at a pressure of 0.03 to 0.08 MPa. This fraction contains most of the polymerizable hydrocarbons formed during pyrolysis in the sense of this invention. The advantage of this process is that for the same amount of raw material for polymerization or. for the same amount of resins produced, it is sufficient to process less heavy pyrolysis gasoline.

because the desired hydrocarbons are present in a higher concentration. This results in smaller dimensions of the vacuum distillation column and lower operating costs.

If the production process based on pyrolysis gasoline is based on all pyrolysis gasoline, the pyrolysis gasoline is first fed to a depentanizer, where the Cg hydrocarbon fraction containing valuable isoprene is distilled off, and the residue from the depentanizer is fed to a vacuum column, where at a pressure of 10 to 40 kPa and a temperature at the top of the column of 75 to 90 °C and 150 to 175 °C at the bottom of the column, the fraction containing benzene, toluene, xylene and most of the Cg aromatics is distilled off, and the residue containing the desired indene, methylindenes and styrene homologues is used as a raw material for polymerization into synthetic resins.

The overhead product from the vacuum column can, for example, be hydrogenated to 1° and subjected to dealkylation to benzene, or hydrogenated to 11° and the contained aromatics obtained by extraction and distillation, or the 1° or 11° hydrogenate can be used as a valuable component of automotive gasoline.

The advantage of the process based on all pyrolysis gasoline is manifested in pyrolysis units where a column is installed for processing pyrolysis gasoline, so the process can be implemented with minimal modifications to the equipment. This process achieves a concentration of the desired polymerizable substances of at least 40%.

The described procedures can be illustrated with the following examples:

Example 1

Heavy pyrolysis gasoline obtained by condensation of pyrolysis gas in a pyrolysis gas water scrubber at a temperature in the head of 36 °C, in the bottom of 80 °C and at a pressure of 0.06 MPa was subjected to vacuum distillation at a pressure of 2.4 kPa and a temperature in the column reboiler of 98 to 100 °C and a reflux ratio of 1.0. 18.3% of distillation residue and 76.7% of distillate were obtained /losses of 5.0% vol./.

The composition of the products was as follows:

Distillate component

Product composition /% wt./ dist. residue

Cg hydrocarbons:

oxyclopentadiene

Cg-Cg nonaromatics benzene toluene

1.4

0.2

3.8

0.1

0.1

Cg aromatics:

p-xylene m-xylene o-xylene ethylbenzene styrene

2.2

6.1

5.7

3.1

17.9

0.1

Cg aromatics:

1-propylbenzene n-propylenebenzene 1,3,5-trimethylbenzene 1,2,4-trimethylbenzene 1,2,3-trimethylbenzene ethyltoluene methylstyrene Indane indene

C _1Q+ non-aromatics and aromatics

0.2

1.3 1, 7

5.3 2.2

10.8

19.6

1.0

8.4 9.1

0.1

1.1

2.1

6.0

0.8

14.6

2.7

36.8

35.5

The distillation residue was subjected to thermal polymerization at 180°C for 5 hours and catalytic polymerization at 180°C for 5 hours with 0.1 wt% AlCl2.

Resins obtained:

thermal polym. catalytic pol. yield % wt. to the rest 20 to 25 22 to 30 softening point ring-ball, °C 102 to 105 95 to 96 color light yellow to yellow light yellow to yellow

Example2

Pyrolysis gas oil with a distillation range of 196 to 320 °C was subjected to vacuum distillation at a pressure of 2.0 kPa, a temperature in the column reboiler of 98 to 100 °C at a reflux ratio of 0.5, and 32.7 vol. % distillate and 67 vol. % residue were obtained (dist. loss 0.3 vol. %).

The composition of the distillate was as follows:

Folder Composition of distillate /% by weight/ Cg-Cg nonaromatics 0.1 C _g aromatics: xylenes 0.2 styrene 0.3 Cg aromatics: n-propylbenzene 0.1 1,3,5-trimethylbenzene 0.2 1,2,4-trimethylbenzene 1.1 1,2,3-trimethylbenzene 4.3 ethyltoluene 0.8 methylstyrene 7.2 indane 2.2 everyday 38.5 ^C 10+ ^{ηβ3ΓΟΓη} ^Υ ^and aromatics /including naphthalene 0.2/ 45.0

The distillate was subjected to thermal polymerization at 200 °C for 5 hours and catalytic polymerization at 200 °C for 5 hours with 0.1 wt. % AlCl ₃ . Unpolymerized portions were vacuum distilled from the product.

Resins obtained:

Thermal polym. Catalytic polym.

yield, and mass.

for distillate 23 to 27 28 to 34 softening point ring-ball, °C 90 to 96 80 to 85 color almost transparent almost transparent

to light yellow to light yellow

Example 3

In the operating equipment, the C _g fraction was separated from pyrolysis gasoline with a distillation range of 70 to 190 °C (heavy pyrolysis gasoline) and the residue was (without prior hydrogenation) subjected to vacuum distillation at a pressure of 20 kPa, a temperature of 162 °C at the bottom of the column and 85 °C at the top. The distillation residue was obtained with a yield of 14% by weight.

Composition of the distillation residue: /% by weight/

styrene 0.17 indane 2.4 everyday 19.5 methylstyrene 20.5 dicyclopentadiene 3.3 aromatics 54.1 /homologies of indene and styrene/

The distillation residue was subjected to laboratory thermal polymerization.

Resins obtained:

yield, wt.%

ring-ball softening point, °C color thermal polymerization

Claims (1)

A process for producing the resins from the heavy products of pyrolysis of hydrocarbons and hydrocarbon fractions thermal and / or catalytic polymerization of unsaturated hydrocarbons, characterized in that the polymerization subjecting fractions from pyrolysis containing mainly indene and its homologues, homologues of styrene and other unsaturated hydrocarbons, _Cg-Q1, preferably a residue from a vacuum distillation of pyrolysis gasoline from a water scrubber of pyrolysis gasoline with a content of 35 to 40% by weight. % indene and 14 to 16% methylstyrene, or a distillate from the vacuum distillation of pyrolysis gas oil containing 35 to 40 wt. % indene and 6-9 wt. methylstyrene, or any residue of vacuum distillation of pyrolysis gasoline after separation of C _g -fractions containing 18 to 20% by weight. % of indene, 18-24% by weight of methylstyrene, and 50-55% by weight of methylstyrene; C _{1Q of} homologues of styren and styrene.