US2346664A - Surrefining of coal-tar derivatives and the like - Google Patents

Description

N O S R O C B. B

lFiled July 28, 1941 PWM.

LA rw SUR-REFINING OF COALTAR DERIVATIVES AND THE LIKE I wmv amwm.

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l INVENTOR.` BEN BENNETT Conson.

Patented Apr., 18, 1944 SURBEFINING F CQAL-TAR DERIVATIVES AND THE fmv Ben Bennett Corson, Swissvale, Pa., assigner to Hoppers Company. a corporation of Delaware Application lilly 28, 1941, SerlaiNo. 404,317l

The present invention relates in general to the treatment of carbonaceous substances such as those produced by the destructive distillation of 4fuels and is more specifically concerned with improvements for enhancing the quality of products derived from coal tars; for example, phenolic compounds.

Amongst the objectsof the present invention is I the provision of improved method and means whereby coal-tar derivatives such, for example, as phenols. and the like, can be cheaply, simply, and continuously produced in a high degree of renement in respect of odor, content-of-sulphur, and also of suitability for employment in processes involving a hydrogenation step.

A further object of invention is the provision of an improved reagent and modications thereoi that are e'ective for the above-stated purpose, whether or not the to-be-treated coaltar derivatives are in the liquid or in the vapor phase, and that are easily regenerative for re-use after a period of operation.

The invention has for further objects such other improvements and such other operative advantages or results as may be found to obtain in the processes or apparatus hereinafter described or claimed.

Relatively pure constituents extracted from coal-ters sometimes have admixed therewith varying small .amounts of diilcultly removable products that alter their normal characteristics to greater or lesser degree. In the case of phenols, for example, these associated products may be present in such minor amount as to be undetectable by the usual determinations, for example, l

of freezing or of boiling points, but may be present in amounts sufcient somewhat to disguisetheir characteristic odors and thus depreciate their commercial value. There may be also present sulphur-containing compounds that importantly reduce the eective life of a sulphursensitive catalyst when the same is employed for the hydrogenation of such phenols.

It has now been found that by bringing phenol, such as that above-described, into contact at an elevated temperature and either in its liquid or its vapor phase, with metallic copper prepared in such form that it presents a large surface to the phenol, the resultant phenol products have a greatly improved odor and that their sul-l phur content is so importantly reduced that they can be economically hydrogenated in processes employing a sulphur-sensitive catalyst.

8 Claims. (Cl. 260427) per, even when itl has a minor content of its oxide, presents to the to-be-treated material, the more effective it becomes for the purpose. Considerable improvement in odor and reduction in the sulphur content of a given phenol has been brought about by passing it in vapor form over copper turnings, copper and bronze powders, and over commercial granular copper oxide that has been previously reduced by appropriately treating it with hydrogen, but, according to the present invention for improving the quality of constituents of coal tar, for example phenols, they are preferably passed in vapor form over nely comminuted metallic copper that is supported on such cheap carrier therefor as pumice, the copperk being distributed over the surface of said pumice in a manner hereinafter described in connection 'with one of the specic examples i1- lustrating the operation and results achievable by the present improvement. It has been found that the use of copper to achieve the stated results renders `the present process commercially feasible for the purification oi even relatively inexpensive products because of its cheapness and eectiveness and the ease with which it can be vprepared in practical formand because, when its activity has been so reduced in operation as to lowed by a stream of hydrogen or hydrogen-con- In general, the more finely-dividedthat is, the greater surface a given quantity of metallic cop' 55 the phenols through the copperlzed pumice is render it impractical of employment, it can be restored for further use in a simple manner to close approximation of its original activity and while it is in situ in a plant lay-out. After a cycle of operation, that is interrupted when the treated phenol no longer exhibits the preferred characteristics to the desired degree, an employed mass of copperized pumice can be shunted out of the flow-path of the to-be-treated phenol and another be switched into operation for use while the former said mass is being regenerated by flowing thereover, while in its containing vessel, a current oi' air or oxygen-containing gas for oxidizing any deposited carbonaceous mate`1 rial and sulphided copper, 4this step being foltaining gas for reducing-the resultant oxidized copper compounds. During the said regeneation steps of oxidation and reduction, temperatures not in excess of about 800 C. and not substantially less than 200 C. for the former step are maintained in the treated mass; in some 'instances the copper has retained its activity when reduced from the oxide at 500 C. but the preferred temperature lies between about 200 C. and 350 C.

A practical liquid-space velocity per hour of about 2.5 where unity is that velocity obtaining when a volume of liquid phenol is passed per hour in vapor phase over an equal volume of copperized pumice; the `particular space-velocity employed in any one instance will naturally depend on such factors as the activity of the purication medium, temperature and pressure of treatment, the yquality of the to-be-treated starting material and vthat desired in the finished product.

In the accompanying drawing forming a part of this specification and showing for purposes of exempliiication a preferred apparatus and method in which the invention' may be embodied and practiced but without limiting the claimed invention specifically to such illustrative instance or instances, the single figure shows a diagrammatic representation partly in elevation and partly in vertical section of apparatus for carrying out the improvement provided by the present in- I vention and-further shows indiagrammatic man- Y ner apparatus wherein Vproducts resulting from. its

` practicecan be optionally hydrgenated.V lIn thev` apparatus shown'i'nthe gure the tolie-treated coal-tar product, -for' exampleA phenol, ist continuously flowed into VtheV vaporizer still -or preheate I through line 'l'.V This device can be anyoneof those well-known inV the art and into intimate contact with the comminuted copper purification medium I5, the said contact ing tube I3 and pass in sequence through valved employed for volatilizing or distillingmaterials.-

A nyofthe usual means-'forsupplying heat thereto lcan'be-employed, and line-8 is hereVv shown for supplying fuel gas for its heating. The tobe-reflned phenolic' vapors admixedwith other materials such asv derivatives of sulphur and ill-smelling constituents that may even boil within the same-range asia relatively pure phenol product, Aleave the apparatus I through insulated line 9 at temperatures usually ranging from about 180 C. to about 200 C. and usually but not necessarily at ordinary pressures, said pressures being sufficient to cause a flow of said vapors through the apparatus that follows. In lspeciiic sure will be found advantageous depending on the boiling point of the to-be-treated material. From line 9, the volatilized materials thereafter flow through either one or the other of the valved I branch li'nes I0, II or I2 to the respective and substantially similar treating units 2, 3 or 4. Three'of such units are shown in parallel arrangement to permit the use of one unit for the treatment of the said phenol vapors while aA second unit is being revivifled or reactivated as will be hereinafter described. The third unit is a spare that allows for uninterrupted operation Ain those cases where one of the other two units is temporarily out of service. The treating unit 2 is shown in vertical section and is typical of the others. It comprises a ,casing or tube I3. a layer of insulation Ill and pack- `ing |5, said packing comprising the preferred copperized pumice provided by the linvention. Any of the well-known.' commercial types oi' insulation can be employed to insulate tube I3, the said tube being constructed of any appropriate material capable of resisting temperatures of about 800 C. The treating unitsl are positioned `vertically with downward ilow therethrough to minimize channeling and maintain uniform contact with to-be-treated vapors throughout said copperized pumice.

The to-be-rened phenolic vapors leaving still I through line 9 can ilow, for example, through valved branch line I to the treating unit 2 and while passing through insulated tube I3 will come branch line IS and line I9, and can be optionally owed through valved line to a hydrogenation unit 5 or, if preferred, they can be owed through valved line 23 to a fractionating column 6.

The rate of flowv of phenol vapors through said tube I3 or the liquid-space velocity per h'our that is feasible to remove sulphur impurities and to edulcorate, that is, to removev foreign odors from the phenol vapors, depends o n such factors as the quantity of said impurities present in the phenol vapors. the particular purification medium employed as well asits available surface for contact, and the quantity of sulphides previously accumulated on the latter.

The refined phenol vapors thatl leave treating tube I3 through valved branch line I5 and line I9 canflow, when valved line 20-is closed, through valved line 23 to a fractionating column 6 for the separation of a phenol product havingy a narrower boiling range.` The vapors flowing from column 6 through` line Y24 enter water co'oled dephlegmator 25 to` be reiluxed, the narrower boilingrange vapors leaving through valved line 25 to be condensed and stored (nctshown)y while higher boiling yaand condensed constituents return to fractionating column 6 through line 21. Then higher boiling phenol product leaves columns through valved line 28V for further. disposition. -1 Itv isvof courseunderstood that instances, either subor super-atmospheric presany additional heat required in column Bvfor the above-described operation can be supplied as required. When valved line 23 is closed, the refined, edulcorated phenolic vapors in line I9 can flow through valved line 20 tol hydrogenaltion apparatus 5 for conversion Ywith a sulphursensitive nickel catalyst, for example, tb cyclo hexanol. The hydrogenation apparatus 5, diagrammatically illustrated in the drawing,-can be one of any well-known types of apparatus chosen with consideration for treatment of the phenol accordingly as it is to be done either in the vapor or liquid phase; The hydrogenated product leaving apparatus 5 can flow either through valved line 2I to suitable storage (not shown) or through valved vbranch line 22 to fractionating Vcolumn 6, where further separation of a narrow- Where treating unit 2, for example, has been in operation for the stated purpose 'a predetermined time, depending mainly on the impurity concentration of said phenol vapors, it will thereafter be necessary for continuous and e'icient treatment thereof to carry on the said refining operation in one of the other treating units while unit 2 undergoes revivication. Thereafter, the said phenol vapors in line 9 that has been previouslyA flowing through valved branch line III, refining unit 2 and valved branch line I6 will ow through, for example, valved branch line I I, re'ning unit 3 and valvedl branch line I1 while said valved branch lines I0 and I6 are closed as are those numbered I2 and I8.

During operation of the instant improvement on the phenolic fraction of coal tar to highly refine it, metallic copper of the-` copperized pumice is usualw converted -to sulphides of copper and some carbonaceous material as welt is laccumulated thereon. In the reviviflcation of such spent copperiaed pumice, the sulphides and carbonaceous material are first omdized with air or other oxygen-containing gas and thereafter the resultant oxidized copper compounds. are again reduced to metallic copper with hydrogen. For this purpose, airat gradually increasing temperatures and within a range defined by about 200 C and 800 C. is flowed through line 20, valved branch line 30 to and through tube I3. The oxidation reaction may become very vigorous, especially at the beginning thereof and can be controlled by first employing a gas of low-oxygen content, for example, air mixed with nitrogen or other inert gas in preferred ratio. The excess air and other gaseous reaction products leave said tube through valved branch line 33 that connects with vent liney 36. After the said oxidation, its resulting oxidation-products in the copperized mass are extensively reduced to metallic copper with a stream of hydrogen at temperatures ranging fromapproximately 250 C. to 350 C., the said hydrogen also being owed through line 29, valved branch line I0, treating tube i3, valved branch line 33 to vent line 35. IThereafter, the treating unit 2 is again ready for another cycle of operation for the stated-purpose. It is preferred to minimize explosion hazards in the treating units by employing an inert, oxygen-free gas as a purge gas before the air oxidation, before the hydrogen reduction and before phenol vapors are again passedthrough them after revivication. `For this reason, all valves should lbe free of leaks when closed.

In the above-given description of `the instant novel process and the employed apparatus for highly refining coal-tar products to improve, for example, their odor and remove constituent sulphuncontact between the reiining media, such as nnely-divided copper or copper-impregnated inerts, and the to-be-treated material, is eiected when the latter is in the vapor phase. rIt has been found that the beneficial results of the invention can be also obt 'in a modification of the des scribed process wherein a coal-tar derivative, for example phenol, is treated in the liquid phase Withthe copperized pumice or lwith other forms ci nnely divided copper. When the process` is practiced in the latter fashion, the toberefined product can be reuxed in the presence of the chosen medium. The time of contact depends on the form oi the chosen refining medium and on the impurity-content of the to-be-treated material and may vary from. about ve to about twelve hours. Thereafter, the so-treated product can be vaporized to separate it from the refining medium and, as above described, the vapors can be directly this wise impregnated with 6.1 per cent by weight of comminuted metallic copper was packed to a depth of about iifty inches in an insulated iron tube having an internaldiameter of 2.2 inches; the total volume occupied therein by the rening medium was about 190 cubic inches. The said iron tube was connected by an insulated pipe with a still for vaporizing the to-be-rened phenol product, which was a product known in the trade as 90% phenol." and was a coal-tar derivative having a melting point of about-36 C. This particular phenol product was chosen since it had both a foreign odor, that somewhat disguised the characteristic odor of phenol, 'and had a sulphur content of about 0.02 per cent by weight. t had been found previouslyA that even a phenol fraction of narrow boiling range derived from this "90% phenol and having a melting point of about 40 C. could not be successfully hydrogenated for any considerable period because suilcient of the sulphur-containing impurities distilled over with thisrelatively pure material to poison in a relatively short time the sulphursensitive nickel catalyst employed for the hydrogenation thereof to cyclohexanol.

The said 90% phenol product was pumped at an approximate rate of two gallons per hour to the still, the volatilized phenol issuing therefrom and having a temperature oi' from` 180 C. to 1900, C. was owed into contact with copperized pumice prepared as above described, the said rate of flow corresponding to a liqiud-space velocity of about 2.5 and an approximate contact time of two seconds. The phenol vapors after this treat-k ment were condensed. The resultant sweetened product had the fresh aromatic odor characteristic of pure phenol and was thereafter ysuccessfully hydrogenated with a sulphur-sensitive nickel catalyst to cyclohexanol, without impairing the spent copperized pumice was regenerated or reviviiied in situ first for about twelve hours with passed to hydrogenation means or to a fraction The following specific examples are illustrative 0f the of the results .obtainable by the operation present process.

Example 1 A quantity of copper'lzed-puinice rening meair increasing progressively in temperature from about 200 C. to 500 C. and' thereafter for approximately six hours with hydrogen at about 300 C. to 350 C. Approximately seventeen cubic feet of air per hour and 1.5 cubic feet of hydrogen per hour, bothmeasured at standard conditions,

' were employed for the oxidation and reduction dium was prepared by soaking pea-sized pumice -in` het, concentrated copper sulphate solution. The"so-impregnated pumice was drained and yiried and thereafter the absorbed copper sulphate was reduced to copper in a stream of hydrogen at about 300 C. Approximately '2.8 pounds of .above-described and the resultant product remained comparable in purity with that produced during the said reagent's initial use. To minimize the hazard of explosion the treating VunitA was purged with nitrogen to sweep out gases and vapors present therein before each ofthe oxidation, reduction and refining steps. During lthe rst hour or so of the oxidation step a mixgen content being thereafter progressively reduced until straight air was employed.

Example 2 The following is an example oi' the beneiicial results obtained when a standard commercial 90% phenol product was refined according to the present invention in the liquid phase while employing ilnely-divided copper as the rening medium. The employed finely-divided copper treating medium was prepared by adding sodium carbonate to a solution of copper sulphate also containing diatomaceous earth. The precipitate of basic copper carbonate on diatomaceous earth was separated by iiltration, dried andthe metalliccopper obtained by reduction with hydrogen at about 300 C. The so-prepared teratingv medium1 comprised about 'Z5 per cent copper and 25 per cent `diatomaceous earth.

An admixture comprising a 90% phenol prod# uct similar to that treated in Example l, and the said copper treating medium in a weight ratio ofabout 100 to 1, respectively, was boiled under substantially complete reiiux for about six .hours and thereafterthe copper treating medium vilas filtered oiland the liquid portion'distilledyi In the distincte, approximateiy `so per cent ofthe' starting material 'was-recovered as phenol ,hav

. slightly above its boiling point. However, when treating other materials having the same origin, ,their/physical' characteristics, the temperature atjwhicli preferred results are obtained'and the 'degiee'tOwhichthey are to be rened will some- `vvhat`gde'termirfie1 the employed procedure and mustbe' empiricallyv determined.

1Y",Itfftlleabovegiven discussion, the"action of copperjalorie has been described as thje f active reagent, 'bi' 1t it interestinj g tol note, that other metals in' combinationV with' 'copper` give y'favoring a'melting point of substahtially 40 C. and

the characteristic odor 'of highly rened phenol. A phenol product having substantially the same melting pointy but recovered fromfrthe starting produced by the copper treatmentr was hydro- 'material without the said coppertgeatment had a decidedly less'agreeable odor. "-,t'he said phenol is more than about 150? C. lotver'j,th

genated' to cyclohexanol within, nickel catalyst without lunusual' reduction in itsactivity due to presence of sulphur. i

There has beendescribed a process, reagents and apparatus'ior treating,- more especially,

otherwise relatively highly refined by-product derivatives lof the carbonization of coal to remove therefrom contaminants that are usually relatively low in yconcentration in 'such derivative products,'yet whosepresence therein can appre' ciably reduce their commercial value for a particular purpose. The present process is adapted to be practiced per se or in combination withother processes for purication and utilization oi' such products; it can -be used to enhance the value of an existing product by further reiiriingv desirable constituents, an for the removal of` which the present process is peculiarly adapted, and especially so for those malodorous constituents and for those ingredients that 'materially reduce the eillciency of certain hydrogenation catalysts.

For treatment of said derivative products acable results and'consequently itis not desired broadly to limit the claimed invention specically'to the use "of copper alone because metallic mixtures in which copper,hasgairiactivefpart are of utility vandincertain instances' have advantages. For example, greater economy ca n yresult in consequenceo'f a lowered temperatureoi hydrogen reduction to'tlfie4 activefiietallic',states, which inthe case of copper admixed' ith zinc tion temperatur e 'ior.fz"inc',fsaid yzifn 1 by itself, being A`an ineiiectivefreageht Also, the more expensive copper can' be partly p ced by cheaper iron in an fadmixture'fof fthese", riietals.

` For example, when a commercial phenolicfproduct that was somewhat .,mfalodorous' lvvashrought into contact at about itsb'oil point and in the vapor phase with iron vv that adbeen 4reduced at about450 C., ,thesaid ated product exhibited no improvement inI A 'or `1`"ed'u'`:t`ion in its sulphur content. Howe 1;, 2y on'y theother hand, an admixture comprisingv about .10 per cent FezOa and 30 per cent CuO was; after reductionin hydrogen at 200 C., an effective treating reagent and saidA reagents activity to edulcorate and remove sulphur 'from said phenolic product was considerably greaterr than would be anticipated onthe basis of its copper content alone; in other words its ironl content, for the instant purpose, showed activity in the presence of copper. Combinations of metals, one of whose constituentsis copper are thus of economic import in the present improvement.

In the case of phenolic compounds that have been produced by the present process, the freshly prepared product is substantially colorless but gradually takes on a pinkish tint, Its color stability can, however, be increased by bringing it at elevated temperatures into contact with such cording to the present invention ordinary pressures are usually employed that are sufiiciently above atmospheric pressure to direct the iiow of said products through the treating and other lalisorptive bodies as clays or gels; rtor instance,

Attapulgus clay or activated alumina. They can be simply employed in combination with the present process by packing them in a treating unit substantially similar to those already described for the active copper-containing reagents and they can be incorporated advantageously into the apparatus, shown in the drawing, be- ,I

tween the treating units 2, 3, and 4, and the fractionating column 6. They .should be'of such Size as to provide a liquid-space-velocity of about 1.0. in the case of Attapulgus clay, to remove accesos color-producing constituents. A sotreatedphe no1 product remains colorless for long periods.

The invention as hereinabove set forth is enri bodied in particular form and manner but may be variously embodied within the scope of'the claims hereinafter made. i

I claim:

1. A process of sur-rehning a phenol containing approximately .02 of sulphur which comprises, passing the same through a body of copper absorbent produced by dispersing a copper compound on an inert porous carrier and then reduced to metallic copper by means of hydrogen and heat.

2. A process of sur-reiining a phenol containing approximately .02 of sulphur which comprises, passing the same through a body of copper absorbent produced by dispersing a copper compound on an inert porous carrierof pumice and then reduced to metallic copper by means of 4hydrogen and heat.

3. A process as claimed in claim 2, and in which the proportion of the copper to the puinice is about six per cent by weight.

which the copper absorbent is comprised oi 75 l0 per cent copper and 25 per cent diatomaceous earth.

6. A process as claimed in claim 1, and in which the phenol is passed through the body of copper absorbent in vapor phase.

is 7. A process as claimed in claim 1, and in which the phenol is passedfthrough the body of copper absorbent in liquid phase.

8. A process as claimed in claim 1, and in which the copper is associated on the carrier with at '2d least one of the group of metals consisting of iron and zinc.

BEN BENNETT CORSQN.

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