US2210395A - Method of treating cracking still residues - Google Patents

Description

g- 6, 1940- w.- H. CARMODY 2.210395 METHOD OF TREATING CRACKING STILL RESIDUES Filed Oct. 12, 1937 PURE .sr/u RES/DUE (Rm/nus: oar/1mm //v 015m LA770N or cur: or LIGHT o/zs mam/cm //v BY- mower cam/v5 of mu) 8 TEAM I DIS TILL l l H/fih' BOIILING OILS RES/N CRACK WITH A161 SIMPLE eesl/vous AROMA T16 o/zs RES/05 HEA7,' e. T0 250 cv I fi Auow RES/DUE SIMPLE r0 SETTLE AROMATIC OILS 'SLUIDEE I 0/LY LAYER FILTER FILTER g 0/L'- CAAIE WAS/1' WITH SOLVENT F/L rm OIL CAKE so4uno/v V STEAM DIST/LL I W on; RES/N INV IN OR. 1 MM ig 7C2 ATTORNEYS.

Patented Aug. 6, 1940 METHOD OF TREATING CRACKING STEL RESIDUES William H. Carmody, Pittsburgh, Pa., assignor to The Neville Company, Pittsburgh, Pa, a corporation of Pennsylvania Application October 12, 1937, Serial No. 168,641

9 Claims.

covered from the wash oil by distillation. Thismixture of light oils is fractionated and the individual cuts are treated so as to obtain commercially pure solvent oils therefrom. The last step of this process is a distillation operation in which the oils are obtained as distillates; the still residue left in the distilling retort is known as pure still residue.

The still residues comprise polymers of unsaturated compounds, mainly in the form of resins, and other reacted bodies which appear as high boiling oils. This still residue has been of such low market value that usually it was disposed of by adding it to coke oven tar, or burned as a fuel, as no more profitable mode of handling it was known.

In my copending application Serial No. 85,747, filed June 17, 1936, now Patent No. 2,149,577, granted March '1, 1939, I have disclosed and claimed a process for treating these still residues so as to recover products of increased value therefrom. That process comprises steam distilling the still residue at elevated temperatures with recovery of high boiling oils and a resinous residue. The high boiling oils and resins obtained by that process possess greater commercial value than the still residues.

In another copending application Serial No. 168,963, filed November 3, 1936, now Patent No. 2,149,577, granted March '7, 1939, I have disclosed and claimed a process for treating the high boiling oils obtained from the pure still residue by practicing the process described in my aboveidentified application. The process described in application Serial No. 108,963 comprises heating and catalytically cracking the high boiling oils so as to obtain simple, and aromatic solvent oils therefrom, as by heating the oil to, say, 265 to 300 C., in admixture with a cracking catalyst, e. g.,,aluminum chloride. Al-

though the process mainly yields these simple aromatic oils and is primarily used for their production, a substantial amount of resinous .residue remains in the cracking retort.

The catalytic cracking of the high boiling oils is carried out by a batch operation, and the more valuable, 1

cracking retorts must be cleaned at the end of each run. This cleaning operation has been difiicult because the resinous residue obtained often solidifies when its temperature is lowered below about C. Thus the residue is dimcult to remove from the cracking retort. This problem is aggravated by the fact that the resinous material can not ordinarily be brought out of the cracking retort hot because it tends to flash and therefore it must be cooled to a rather low temperature before exposing it to the atmosphere. Necessarily the removal of the residue has been a difiicult operation, and unsuccessful attempts have been made to provide a better method for removing the resinous residue from the retort. One of the objects of the instant invention is to provide an uncomplicated method of treatment by which the cracking still residue produced in the cracking of aromatic solvent oil recovered .from pure still residues can cheaply and easily ment of the invention.

I have discovered that if the residue produced in cracking high boiling oil recovered by steam distillation of pure still residues be diluted with a less viscous lower melting substance obtained in the recovery of coke oven light oils, the cracking still residue of the resulting mixture can readily be cooled without attendant solidification. This mixture may then be thinned further, as with a low boiling aromatic oil, after which the mixture may be allowed to settle to produce an oily supernatant layer which is decanted from the remaining material and subjected to steam distillation to drive off the volatile oils therein and leave a resinous residue'of improved properties.

The cracking still residue with which the instant invention is concerned is largely a product of the cracking reaction. The catalyst first breaks down a portion of the high boiling oil present with the production of unsaturated units and active hydrogen and it then acts to aid in polymerizing the unsaturated units into resinous materials. Some of the remaining uncracked oil appears to be hydrogenated to form oils and resins resistant to cracking, and these oils together with unspent catalyst substantially commay be of substantial amount, e. g., between 12 to 15 per cent of the original still residue.

After the cracking of the high boiling oils recovered from still residue has proceeded to sub stantial completion, a less viscous lower melting material than the resulting residue is slowly added thereto. I have discovered that excellent and unpredictable results are obtained when still residue is added to the cracking still residue. The still residue is slowly added to the cracking still residue while heat is applied to the cracking retort to maintain the contents at approximately 250 C. This heating serves to dissolve a portion of the resins in the oils present and in general to thin the mixture so that more intimate contact with the catalyst results. As a portion of thestill residue comprises high boiling uncracked oils, and also due to the factthat uncracked'oils remain in the cracking retort, a slow cracking reaction occurs during the addition of the still residue because some of the aluminum chloride has at least partially retained its catalyzing ability. Thus some simple solvents are distilled from the. mixture and may be recovered in any desired manner. After this, the mixture may be cooled to atmospheric temperature without danger of solidification.

Usually further thinning is desirable, either before or after withdrawing the residue from the retort, so that the mixture may be handled and treated more easily. This thinning may be done by adding the necessary volume of any suitable solvent, such as the simple aromatic oils obtained by cracking pure still residues, then the mixture is allowed' to settle until a definite oily -layer ,manner, while that remaining can be recovered by putting the sludge through a filter press and washing it with a solvent, such as simple aromatic oils. The oil recovered from the filtration operation and the washings of the filter cake are then added to the decanted oil and the entire voliune is subjected to steam distillation. The temperature to which the oil is heated when being steam distilled varies with the particular mixture of oils being treated, but excellent results may be obtained by using temperatures from 275 C. to 300 C. Distillation is continued until substantially no oil is carried over by the steam.

After distilling ofi the oils, a resinous residue remains in the distilling retort. This comprises a black resin which is quite brilliant and which has a bright fracture. Upon analysis the ash content of a typical resin, having a melting point of 118 C., was found to be 1.26 per cent, which was far below the expected ash value in that.

resin produced from still residues usually contains up to 18 per cent ash. Thus at least 8 or 9 per cent ash'would be expected in the resin produced in accordance with this invention. The resin was 17:2 per cent insoluble in V. M. 8; P. naphtha.

While the nature of the reactions transpiring by which the ash content is-reduced is not certain, it is'thought that the aluminum chloride present in the cracking still residue reacts in some manner with the alkaline ash of the still residue and results in a more or less complete precipitation or settling out of both constituents.

A typical example of the portions of the various ingredients used in my novel treatment is as follows: 550 cc of pure still residue dry steam distillate were cracked with aluminum chloride and to theresulting resinous residue 217 grams of pure still residue were added, keeping the whole mass heated to about 250 during the addition. Upon cooling the mixture it was further diluted with a light solvent after which the solution was settled,.the top layer removed and distilled to obtain the final resin which was black, brilliant and had a bright fracture and ash content of 2.6 per cent. About 230 grams of the resin were finally obtained. In addition to the desirable physical properties and appearance of the resin obtained, the percentage yield is such that it enhances the commercial value of the instant process.

In a modification of my novel process the cracking still residues are diluted with high boiling oil which is obtained by the steam distillation of still residues. Suitably there is used high boiling oil in an amount corresponding, by volume, to the residue. This oil is slowly added to the cracking retort while the temperature of the resulting mixture is maintained. above 240 C. Then the mixture is cooled to atmospherictemperature at which time it appears as a thick, viscous, grainy material. Next the mixture is thinned, settled and decanted as in the embodiment described'hereinabove; However, the oily layer produced in this manner carries an appreciable amount of catalyst which may be removed in any suitable manner. Thus, it may be washed with water in order to remove all but traces of the catalyst therefrom. The resulting washed oil is then'steam distilled as in the preferred practice to produce volatile oils and resinous residue. A typical resin produced by this process had a melting point of 92 C. and an ash content of only .03 per cent. It was 6.6 per cent insoluble in V. M. & P. naphtha.

In the commercial practice of my modified procedure 7300 gallons of high boiling oil have been cracked with 4400 pounds of aluminum chloride to produce about 4400 gallons of cracked distillate and approximately 2900 gallons of residual oil and resin mixed in with the catalyst. In completing the treatment of this mixture, in accord ance with the present invention, between 8000 and 9000 pounds of a black resin having properties as described were obtained.

It will be understood that in some instances it may be desirable to recover the resins and oils present in the cracking still residue in a different manner from that herein described. In all events, after practicing the initial steps of the instant process, the cracking still residues can be pumped or drawn from the cracking retort at any desired temperature with no danger of them solidifying in the retort or flashing when exposed to the atmosphere.v

, A further advantage of the process is that the materials added to the cracking still residues to permit their convenient withdrawal from the cracking retort are readily available and are readily recovered subsequently. Also, the addicontents, that they are particularly adapted for use where a bright finished appearance is'desired. Thus in practicing the process of the invention not only are useful products obtained, but also 75 I v a serious problem to the art has been solved by an inexpensive, uncomplicated mode of procedure.

According to the provisions of the patent statutes, I have explained what I now consider to be the preferred practice of my invention. However, I wish it to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

I claim: a

'1. That method of treating aromatic solvent oil recovered from pure still residues derived from fractionation of light oils produced in high temperature by-product coking of coal, which comprises heating and catalytically cracking the solvent oil with aluminum chloride,- diluting the hot cracking still residue with a less viscous lower melting and high boiling substance obtained in the recovery of coke oven light oils, allowing the mixture to settle with production of an oily layer, decanting the oily layer from the resulting sludge, and steam distilling the decanted oily layer to distill oil. and recover the volatile oils therein and to obtain a resinous residue.

2. That method of treating aromatic solvent oil recovered from pure still residues derived from fractionation of light oils produced in high temperature by-product coking of coal, which comprises heating and catalytically cracking the solvent oil with aluminum chloride, diluting the hot cracking still residue with a less viscous lower melting and high boiling substance obtained in the recovery of coke oven light oils, cooling the resulting mixture, thinning the mixture further with low boiling aromatic oil, allowing the mixture to settle with production of an oily layer, decanting the oily layer from the resulting sludge, and steam distilling the decanted oily layer to distill ofi and recover the volatile oils therein and to obtain a resinous residue.

3. That method of treating aromatic solvent oil recovered from pure still residue derived from fractionation of light oils produced in high temperature by-product coking of coal, which comprises heating to a cracking temperature a mixture of the solvent oil and aluminum chloride cracking catalyst and taking oif overhead volatile cracking products, thinning the resultant hot cracking still residue with pure still residue 4. That method of treating aromatic-solvent oil recovered from pure still residue derived from fractionation of light oils produced in high temperature by-product coking of coal, which comprises heating to a cracking temperature a mixture of ,the solvent oil and aluminum chloride and taking off overhead volatile cracking products, slowly thinning the resultant hot cracking still residue with pure still residue and maintaining the cracking still residues above 250 C. during the thinning thereof, cooling the mix ture, further thinning the mixture with low boiling aromatic oil and then allowing it to settle with production of an oily layer, decanting the oily layer, and steam distilling the oily layer to drive off at least a portion of the volatile material therein and obtain a resinous residue.

That method of treating cracking still residues produced in the aluminum chloride cracking of aromatic solvent oil produced from pure still residues derived from fractionation of light oils produced in high temperature by-product coking of coal, which comprises slowly feeding a high boiling coke oven light oil into the hot cracking still residues to lower the solidifying temperature thereof, cooling the mixture and then further thinning 'it'with low boiling aromatic oil, settling the mixture with production of an oily layer and decanting the oily layer, and steam distilling the oily layer to drive off volatile oils therein and recover a resinous residue 6. That method of treating cracking still residues produced in the aluminum chloride catalytic cracking of aromatic solvent oil produced solidifying temperature thereof, maintaining the cracking still residue at a temperature above 240 C. during the addition of the light oil, cooling the mixture and then further thinning it with low boiling aromatic oil, settling the mixture and decanting the oily layer which rises to the top thereof, washing the oily layer with .water to remove catalyst therefrom, andsteam distilling the washed oily layer to drive off volatile oils therein and recover a resinous residue.

'7. That method of treating aromatic solvent oil recovered from pure still residuesderived from fractionation of light oils produced in high temperature 'by-product coking of coal, which comprises heatingand catalytically cracking the solvent oil. with aluminum chloride, diluting the hot cracking still residue in the cracking still resulting sludge, and steam distillirig the decanted oily layer to distill off and recover the volatile oils therein and to obtain a resinous residue.

8. That method of treating aromatic solvent oil recovered from pure still residue derived from fractionation of light oils produced in high temperature by-product coking of coal, which come prises heating to a cracking temperature a mixture of the solvent oil and aluminum chloride and taking off overhead volatile cracking products, slowly thinning the resultant hot cracking still residue in the cracking still with pure still residue and maintaining the mixture above 250 C. during the thinning thereof, withdrawing the mixture from the still, cooling the mixture, further thinning the mixture with low boiling aromatic oil, allowing the withdrawn thinned mixture to settle with production of an oily layer, decanting the oily layerand steam distilling it to drive ofi at least a portion of the volatile material therein and obtain a resinous residue. 9. That method of treating cracking still resi-. due produced in the aluminum chloride cracking of aromatic solvent oil produced from pure still residues derived from fractionation of light oils produced in high temperature by-product coking of coal, which comprises slowly feeding a high ture thereof, maintaining the cracking still residue in the cracking still at a temperature above 240 C. during the addition of said light oil, withdrawing the resultant mixture from the cracking still, cooling the mixture and further thinning it with low boiling aromatic oil, settling the withdrawn and thinned mixture and decanting the oily layer which rises to the top thereof, washing said oily layer with water to remove catalyst therefrom, and steam distilling the'washed oily layer to drive ofi volatile oils therein and recover a resinous residue.

WILLIAM H. CARMODY.

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