US2132365A - Treatment of hydrocarbons - Google Patents

Description

Oct. 4, 1938. c. c. TOWNE TREATMENT OF HYDROCARBONS Filed Dec. 18, 1937 Patented ct. 4, 1938 Charles G. Towne, Beacon, N. Y., assigner to 'litre 'llexas Company, New York, N. Y., a corporation of Delaware Application December 18, i937, Serial No. 130,555

Claims.

This invention relates to the manufacture of motor fuel and resins from hydrocarbon oils, and has to do particularly with a process in which hydrocarbon oils are converted into a. motor fuel naphtha having antiknock properties, the extraction of this naphtha with a selective solvent to form an extract in which the aromatics and unsaturates are in concentrated form, and the treatment of the resultant extract with a polymerizing agent to form a resin.

It has been known heretofore that cracked hydrocarbon distillates may be treated with an anv hydrous metallic halide catalyst to convert unsaturated and aromatic constituents thereof into w resins. However, in the manufacture of resins from cracked distillates, such as commercial cracked gasolines, there is diiilculty in obtaining a resin of satisfactory yield and quality due to the unsatisfactory nature of the product treated, particularly with respect to the resin-formingv constituents. An object of the present invention is to overcome this diiliculty.

In accordance with the present invention, the manufacture ofthe cracked distillate is combined with the resin-forming operation to form a unitary process, whereby both an improved cracked distillate, from the motor fuel standpoint, is obtained as well as improved quality of resin. By practicing the invention with such a unitary process, it is possible to obtain a high antiknock gasoline and good quality resin without substantial sacrice in yields. The improved results are due at least in part, to improved methods of operation, including the extraction of the cracked distillate with a selective solvent,

whereby the resin-forming constituents are concentrated and separated from the non-resinforming constituents which are usually of lower antiknock value and may be recycled to the conversion operation. 4Furthermore, the invention permits more drastic conversion conditions to be maintained in the conversion operation due to the more eiiicient utilization of the normally gaseous hydrocarbons formed, comprising retreatment of these gaseous hydrocarbons in the system to produce polymerization and reactions in the nature of gas reversion with the hydrocarbon oil undergoing conversion.

In practicing the invention, hydrocarbon oil charging'stock is subjected to conversion conditions of temperature and pressure to form a motor Afuel fraction, such as cracked gasoline.

Charging stocks which may be treated may be any heavy oil suitable for the conversion into lower boiling products, such as naphtha, gas

oil or reduced crude. The invention is particularly adapted to the reforming of naphtha in which a naphtha of low antiknock value is' subjected to conversion conditions to eiect transformation of hydrocarbons of low antiknock 5 value into products of improved antiknock value. Such naphthas include virgin naphthas as Well as heavy ends of both virgin and cracked naphthas. The conversion operation may be carried out utilizing the principle of gas reversion l0 wherein the oils are subjected to conversion conditions in the presence of normally gaseous hydrocarbons, which may be those developed and recycled in the system or all or in part those from an extraneous source, such as natural or refinery l5 gases, or fractions thereof, such as propane or butane or mixtures of propane and butane.

The cracked naphtha is subjected to treatment with a selective solvent to eifect separation between the parains and the olefins and aro- 20 matics. Solvents which may be used for this purpose are sulfur dioxide, ortho nitrodiphenyl ether, ortho nitrodiphenyl and para-aminodiphenyl. I prefer to use liquid sulfur dioxide, according to the methods disclosed in U. S. Pat- 25 ents 911,553 and 1,526,665 of Edeleanu and U. S. Patent 2,028,121 of Cottrell.

The extract separated from the cracked distillate is subjected to a resin-forming operation by treatment under suitable conditions with a 30 metallic halide polymerizing agent, such as iron and zinc choride, preferably anhydrous aluminum chloride. The method disclosed in the patents to Thomas and Hochwalt 1,836,629 and 1,982,707 may be used. 35

The invention will be further understood from the following description which should be read in connection with the accompanying drawing showing diagrammatically one form of apparatus for carrying out the process of the invention.

Referring to the drawing, the oil to be converted is charged by the pump l through line 2, heat exchanger coils 3 and d, 4and line 5 to heating coil 'l located in a heater or furnace 8. In the heating coil l, the oil is subjected to con- 45 version conditions of temperature and pressure which may be about 800 to 1000 F. and 200 to 1000 pounds for cracking higher boiling oils into lower boiling oils, or about 900 to 1100 F. and 200 to 1000 pounds for naphtha reforming. The 50 conversion products are transferred through the line 9 to a separator l0 in whichV any high boiling products, such as residuum; recycle stocks or other carbonaceous material are separated and withdrawn from the lower portion thereof. 'I'he 55 upper portion of the separator I0 may be cooled by the heat exchange coil 4, referred to heretofore. The uncondensed vapors and gases are passed from the upper portion of the separator I0 through the vapor line II to a fractionator I2. In this fractionator the cracked distillate is condensed, with the aid of the cooling coil 3, and collected in the lower portion thereof. The normally gaseous hydrocarbons uncondensed in the fractionator I2 are passed through the line I4 to a fractionator I5 .wherein the heavier constituents such as the' C3 and C4 hydrocarbons are condensed and separated from the fixed gases which are released from the top of the fractionator through the line I1. The condensed normally gaseous hydrocarbons are withdrawn fromthe lower portion of the fractionator I5 by the pump I8 and recycled through the line I9 to the heating coil 1. The normally gaseous hydrocarbons recycled through the line I9 may be augmented by extraneous natural or refinery gases introduced into the fractionator I5 through the line 20. The recycling of the normally gaseous hydrocarbons is optional but is preferred because it has been found that much more drastic conditions may be maintained in the heating coil by recycling these gases, whereby more extensive conversion may be effected and a product of improved antiknock value and increased unsaturate and aromatic content may be obtained.

The apparatus shown in the drawing is obviously diagrammatic and may be modified to carry out any well known or preferred type of cracking or reforming operation. For example, reaction or soaking drums and additional fractionators may be used. The apparatus is adapted for a` once-through operation such as commonly used in naphtha reforming. However, it may be modied to provide for carrying out recycle operations of the clean or super-clean type. Also operations running to fuel oil or coke are contemplated.

The converted naphtha collected in the bottom of the fractionator I2 is withdrawn by the pump 22 and forced through line 23 to a mixer 25. In the line 23 is a cooling coil 26 located in an exchanger 21 through which may be passed a refrigerating medium to cool the distillate to a temperature suitable for the subsequent extraction in the mixer 25. Such temperatures will depend upon the solvent used, for example with sulfur dioxide temperatures of about 40 F. or lower may be used. In the mixer 25 the distillate is intimately contacted by a stirrer 28 with a selective solvent introduced through the line 29. The mixture is drawn from the bottom of the mixer through the pump 30 and line 3l, and introduced into a settler 32 wherein the product is allowed to separate into extract and rainate phases. If the solvent is of higher specific gravity than the oil, the extract phase will separate in the bottom of the separator 32, while the rainate, comprising the undissolved or parafin hydrocarbons, collects in the top of the settler. The raffinate is withdrawn through the pump 33 and line 34 to a stripper or still 35 wherein the solvent is distilled off and passed through vaporline 36 and condenser coil 31 to the tank 38. The raffinate freed ,from solvent is conducted from the bottom of the still 35 through the line 39 andl all or a portion thereof forced by pump 40 through di and line it to the heating coil 1. All or a portion of the raffinate may be by-passed through the line d2 to the accumulator 44. A portion oi? the ranate may be passed through line 45 to 50 to a still 52. `rated from the extract by fractional distillation the polymerizer 41 to be used as a solvent or diluent.

The extract comprising the solvent and dissolved hydrocarbons, including olenns and aromatics is withdrawn from the bottom of the settler 32 by the pump 49 and forced through line In this still the solvent is sepaeither by release of pressure or by addition of heat, for example, by heating coil 53 located in the lower portion thereof. In case the solvent is of lower boiling point than the hydrocarbon oil, as in the case of SO2, the vapors of the solvent pass from the top of the still through the vapor line 55 and condenser 56 to the accumulator 38. 'Ihe solvent may be withdrawn from the accumulator by the pump 51 and recycled through the line 58 to the mixer 25. The still bottoms comprising the extracted hydrocarbons are withdrawn from the bottom of the still by the pump 60 and forced through the line 6I to the polymerizer 41. It will be understood in case the solvent is of higher boiling point than the hydrocarbon extract that the hydrocarbons may be recovered as a distillate whiley the solvent will remain as the bottoms in the still 52. In any case, however, the ultimate disposition of the solvent and the extract is intended to be the same.

In the polymerizing chamber 41 the hydrocarbons are contacted by means of the stirrer B3 with a polymerizing catalyst which may be introduced through the line 64. The amount of catalyst is usually about 1 to 5% and preferably about 3% by weight. A suitable diluent may be added to the polymerizer, if desired, through the line S5 or naphtha'from line 45 may be introduced thereto through the line 45, referred to heretofore. The diluent, which may be naphtha or benzol or other solvent, is intended to be added, if necessary, to maintain the proper consistency of the products in the polymerizer. The temperature in the polymerizer is usually maintained at about to 210 F. and preferably about 140 to F. This temperature may be maintained by a heating jacket surrounding the polymerizlng chamber or any other suitable means. The reaction time required in the polymerizer is usually around 10 to 30 minutes although considerably longer periods of time, as much as 2 or 3 hours, may be used if necessary. 'I'he reaction products are withdrawn from the bottom of the polymerizer by the pump 61 and forced through the line 68 to a settler 10 wherein any sludge is allowed to settle out and is drawn off from the bottom thereof through the line 12. About 3 to 5% of sludge may settle out in the settler 10 and may be treated for the separation of a resin, as will be described hereinafter in connection with the main product.

A product substantially free from sludge is withdrawn from the settler 10 through the pump 13 and line 14 to a still 15. In this still the materials are contacted with an alkaline material, such as a 10% solution of sodium carbonate, introduced through the line 11 to effect neutralizatinon of acids and decomposition of the metallic halide hydrocarbon compounds. Steam may be introduced into the lower portion of the still through the line 'It to accelerate decomposition and to effect distillation of ,low boiling hydrocarbons and diluent. The mixture of resinous material and aqueous salt solutionris withdrawn from the bottom of the still through the pump 80 and line ai to settling chamber 82 wherein separation is allowed to take place and the aqueous the fractionator 88.

neutralization products withdrawn through the line 84 and the resin through the line 85.

The vapors are removed from the top of the still 15 through vapor line 81 and introduced into In this fractionator the higher boiling hydrocarbons or diluent are condensed and withdrawn from the lower portion thereof through the line 89 by pump 90. A portion or all of this material may be recycled through the line 9| and line 92 to the polymerizer 63, or through the line and lines 4l and i9 to the heating coil l. The uncondensed vapors are conducted from the top of the fractionator 88 through the vapor line 93 and condenser 94 to an accumulator 44. The product collected in the accumulator 44 is ordinarily highly aromatic and may contain a large proportion of benzol and toluol. A portion of this product may be recycled to the polymerizer as a diluent, if desired, or may be combined, all or in part, in accumulator 49 with the naphtha from line 42, referred to heretofore, to form a high antiknock motor fuel product. A

The resin withdrawn from the settler 82 may be ready for use, although ordinarily it is desirable to mix therewith a suitable thinner or drier. A nished product, such as one suitable for use as a protective coating, may contain about 25% vof a thinner, such as naphtha. The resin is a light colored product and is suitable for use in paints and varnishes.

As an example of the operation of the invention, a straight run naphtha of about 40 octane value is subjectedvto reforming at a. temperature of about 1050" F. and under a pressure of about 1000 pounds. The reformed naphtha is separated and the normally gaseous hydrocarbons comprising C3 hydrocarbons and lighter and all or a portion of the C4 hydrocarbons, are subjected to further fractionation under about 800 pounds pressure to separate the xed gases, including the methane and hydrogen and all or a portlonof the C2 hydrocarbons. The heavier normally gaseous hydrocarbons are recycled to the reforming operation. The amount of recycle gases is approximately 25% of the fresh charge. About 85l to 90% of reformed naphtha of about 75 to 80 octane is obtained 'I'he reformed naphtha is lsubjected to solvent extraction with liquid SOz at about 40 F. Using a ratio of solvent to naphtha of about 1:1, an extract yield of about 40%, and a raillnate yield of about 60%v are obtained. A portion of the ramnate, amounting to about 25% of the furnace charge, is recycled to the reforming operation. The extract is treated with about 3% by weight of the anhydrous aluminum chloride at about to 160 F. for about 2.0 minutes. 'Ihe resulting product, after the separationbf sludge, is treated with an aqueous solution of 10% sodium carbonate in suflcient amount to elfect neutralization and the mixture is then distilled. About 70 to75% of a light oil, based on the naphtha extract and consisting largely of benzol and toluol is recovered as a distillate which is combined with the reformed naphtha. product to form a nished motor fuel. A resin is separated from the undistilled mixture, comprising resin and salt solution. The resin amounts to about 25% of the mixture after dehydation.

. The present invention has the advantage of permitting deep cracking or reforming of the oil,

whereby naphtha of high antiknock value and containing a large proportion of unsaturates and aromatics is obtained. Whereas normally considerable loss would be experienced as a result of gas formation during the drastic conversion operations, according to the present invention, these gases are largely converted into naphtha products of unsaturated or aromatic character. The naphtha produced is highly satisfactory for the production of resins and also affords a means of producing a high yield of relatively pure aromatic compounds, such as benzol and toluol.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

l. The process which comprises subjecting hydrocarbon oil to a cracking operation to convert higher boiling oils into lower boiling oils of the class of gasoline, separating from the cracked products a cracked naphtha, extracting said naphtha with a solvent having selective solvent properties for unsaturated and aromatic' hydrocarbons, separating an extract containing said aromatic and unsaturated hydrocarbons in concentrated form, and treating said extract With an anhydrous metallic halide polymerizing agent to produce a synthetic resin.

2. The process which comprises subjecting hydrocarbon oil and normally gaseous hydrocarbons to conversion conditions under temperatures sufcently high to produce gasoline hydrocarbons, separating from the reaction products a naphtha fraction containing said gasoline hydrocarbons, extracting said naphtha fraction with a selective solvent thereby producing an extract rich in oleiinic and aromatic hydrocarbons, and treating said extract with an anhydrous metallic halide polymerizing agent to produce a synthetic resin.

3. The process which comprises subjecting a naphtha of low antiknock value to reforming temperatures whereby hydrocarbons of low antiknock value aretransformed into hydrocarbons of high antiknock value, extracting the reformed naphtha with a selective solvent to separate oleflnic and aromatic hydrocarbons from paraf,

nic hydrocarbons, separating an extract containing olens and aromatics in concentrated form, and treating said extract with an anhydrous metallic halide polymerizing agent to produce a synthetic resin.

4. The process which comprises subjecting a naphtha of low antiknock value in the presence of normally gaseous hydrocarbons to reforming temperatures suiciently high to eiect transformation vof hydrocarbons of low antiknock value into products of high antiknock value, including substantial amounts of unsaturates and aromatics, subjecting the reformed naphtha to solvent extraction with a selective solvent adapted to effect substantial separation of unsaturates and aromatics from paraiins, separating an extract fraction containing 'the unsaturates and aromatics in concentrated form, and treating said fraction with an anhydrous metallic halide polymerizing agent to produce a resin.

5. A process according to claim 4 in which the polymerizing agent is aluminum chloride.

CHARLESC. TOWNE.

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