US2913397A

US2913397A - Hydrogenolysis of coal hydrogenation products

Info

Publication number: US2913397A
Application number: US610795A
Authority: US
Inventors: Jr James V Murray; John D Fales; Marion A Eccles
Original assignee: Union Carbide Corp
Current assignee: Union Carbide Corp
Priority date: 1956-09-19
Filing date: 1956-09-19
Publication date: 1959-11-17
Anticipated expiration: 1976-11-17

Description

Ow Oh O0 Om Ov Om ON O- O 5 Sheets-Sheet 1 J. V. MURRAY, JR., ETAL HYDROGENOLYSIS OF COAL HYDROGENATION PRODUCTS Nov, 17, 1959 Filed sept. 19, 1956 '9, aunlvuadwn smnloe /Nl/ENTORS` JAMES v. MUR'RAY,JR. JOHN D. FALEs MAR|oN A. EccLEs By gwcbx FM^` ATTORNEY 5 Sheets-Sheet 2 J. V. MURRAY, JR., ET AL HYDROGENOLYSIS OF COAL HYDROGENATION PRODUCTS Nov. 17, 1959 Filed Sept.

Nov. 17, 1959 J. v. MURRAY, JR., ETAL 2,913,397

HYDRoGENoLYsIs oF com. HYDROGENATION PRODUCTS Filed sept. 19, 195e 5 sheets-sheet s omni- .55 .Fzmu im .Pro-m3 D, BtlnlVtI-ldwl QNI'IIOE /Nl/ENTORS JAMES V. MURRAY,JR. JOHN D. FALES MARION A. ECCLES ,9v A M ATTORNEY u Nov. 17, 1959 J. v. MURRAY, JR., ETAL 2,913,397

HYDROGENOLYSIS OF COAL HYDROGENATION PRODUCTS Filed sept. 1e, 195e 5 sheets-sheet 4 loo l N1 /NvE/v Tons JAMES V. MURRAY,JR. JOHN D. FALES n MARION A. ECCLES A TTORNEY Nov. 17, 1959 J. V. MURRAY, JR., ETAL HYDROGENOLYSIS OF COAL HYDROGENATION PRODUCTS 5 Sheets-Sheet 5 Filed Sept. 19, 1956 OO VQ .LO 9 om w a. um w3 Hw OWN oom

/Nl/E/vroRs JAMES V. MURRAY,JR. JOHN D. FALES MARION A. ECCLES .Maf @ra-Ja.

Y ATTORNEY HYDROGENOLYSIS OF COAL HYDROGENATION PRODUCTS James V. Murray, Jr., South Charleston, John D. Fales,

St. Albans, and Marion A. Eccles, Nitro, W. Va., assgnors to Union Carbide Corporation, a corporation of New York Application September 19, 1956, Serial No. 610,795

'14 Claims. (Cl. 208-107) This application relates to chemical processes. More particularly it relates to an improvement in processes for obtaining chemicals from coal.

Various processes have been proposed for the purpose of obtaining chemicals from coal. Among the most promising of these have been those involving coal hydrogenation. Broadly speaking, such processes encompass contacting the coal with hydrogen in such a manner that the coal is converted to gaseous and liquid products, p lus a. pitch residue, and in most instances a small amount of ash. While such processes have made available a vast number of chemicals from coal, the very prolificacy of these processes, in terms of the variety of chemical compounds produced thereby, has raised the problem of separating these compounds, which is highly important to the economic feasibility of the entire coal hydrogenation process.

Our present improvement is directed to a hydrogenolysis of coal hydrogenationl products, whereby the individual compounds comprising such -products are de-v alkylated and/or aromatized to compounds of simpler structure which can be readily separated and recovered. In the process of the invention the material to be processed, as for example the liquid product of coal hydrogenation, is subjected to reaction with hydrogen at elevated temperatures and under increased pressure, in the absence of a catalyst, for the purpose of achieving the desired hydrogenolysis and consequent simplification of the product. For a full understanding of the invention, a detailed consideration of a typical coal hydrogenation product which can be benefited by the process of the invention will be of value. In a typical liquid product from coal hydrogenation, there will be found a large number of different compounds, as many as 200 or more. While certain ring structures, as for example the benzene ring and the naphthalene ring, predominate, such a structure will be found in a wide variety of actual compounds which will vary in degree of saturation, type of substituents on the rings, number of such substituents, etc. Moreover, in most cases liquid coal hydrogenation products will contain compounds having a wide range of boiling points, yet each having a boiling point only very slightly different from one or more other compounds in the liquid product.

Among the coal hydrogenation products to which the invention is applicable is the liquid and semi-liquid portion of the whole product of the coal hydrogenation process, including the pitch, after removal of the gaseous constituents and the ash. This liquid product can have a boiling point range of from about 75 C. at atmospheric pressure up to about 350 C. at reduced pressures of as low as 50 mm. of mercury. Such a coal hydrogenation liquid product with its 200 or more usual constituents is conveniently divided by boiling temperature range into three main fractions or categories.

The iirst is a light oil fraction which may be approximately defined as that portion of the whole product having a boiling temperature range between 75 C. and

2.704 iC. at atmospheric pressure. This fraction contains nited States Patent D mais? Patented Nov. 17, 1959 a large number of aromatic ring compounds, including some nitrogen bases and phenolic compounds. When the nitrogen bases and the phenolic compounds have been removed the product is commonly known as neutral light oil. This neutral light oil is comprised predominantly of benzene and naphthalene and various other compounds having either the benzene or naphthalene ring structure. Some of these latter compounds are those with less aromaticity than benzene or naphthalene'while-a Vast number are substituted benzenes or naphthalenes. The substituted benzenes and naphthalenes may have one or more alkyl groups attached to the ring and these alkyl groups or chains may be composed of from 1 to 5 or more carbon atoms.

The second major fraction of the coal hydrogenation product is commonly referred to as the middle oil fraction and has a boiling temperature range at atmospheric pressure of from 270 C. to 330 C. This fraction is comprised predominantly of substituted ring compounds containing the basic ring structure of benzene, Vnaphthalene, iluorene or phenanthrene, while a smaller percentage of these are present as the unsubstituted aromatic compounds themselves. The majority are the hydrogenated and the alkyl substituted derivatives of benzene, naphthalene, uorene or phenanthrene. As in the light oil these derivatives vary in degree in the number of side groups attached to the ring and the number of carbon atoms in the side groups or chains.

A third major fraction of liquid product of coal hydrogenation is referred to as heavy oil. This heavy oil comprises the compounds of the liquid product having a boiling temperature above 330 C., but not including the pitch. It is comprised predominantly of complex multiple ring compounds, particularly phenanthrene, fluoranthene, carbazole and pyrene and their alkyl-substituted derivatives.

Yet another fraction of the coal hydrogenation liquid product is the semi-liquid pitch. The pitch is that portion of the coal hydrogenation product remaining after the ash and unreacted carbon is removed by filtration and the light oil, middle oil and heavy oil are removed by distillation, Ordinarily a solid at room temperature, coal hydrogenation pitch has a softening point temperature above 50 C. It is composed principally of very high boiling condensed ring compounds, and is substantially soluble in hot pyridine.

Because of the proximity of the boiling temperatures of the compounds making up the whole liquid product, the separation and recovery of individual compounds is made extremely diicult. Fractional distillation is incapable of making such separations and recourse must be had to solvent extraction and other complicated and expensive methods of separation. Even so basic a separation as that of the aromatic compounds from the nonaromatic compounds is impossible by distillation alone. The mixtures of compounds obtained, even in a fraction or cut with a relatively small boiling temperature range, are of limited usefulness.

As a solution to this problem of a highly complex product a .number of separation methods have been employed. Foremost among these have been solvent extraction processes wherein selective solvents are used to extract compounds or groups of compounds. A number of such processes are workable and can be employed to greatly decrease the complexity of the coal hydrogenation process. Separation of individual compounds by such processes are rare, however, and their usual product is a group of homologous or closely related compounds. Any such separation process is by nature a complicated and expensive one and adds greatly to the cost of producing chemicals from coal. Most such separations additionally require fractional distillation to separate the solvent from the extract and to purify the product.

In our solution to the problem of the difficult to separate product produced by coal hydrogenation we have taken into consideration the following. While a wide variety of individual compounds are produced, only a relatively few have wide application and find a ready market. For example, benzene, naphthalene, toluene and phenol are basic aromatic chemicals and are in constant demand. Likewise the methyl and ethyl substituted aromatic compounds have many uses. The highly alkylated aromatics, however, have much more limited direct applications and there is no economic incentive to recover highly substituted compounds individually. Thus it would be desirable in a coal hydrogenation process to produce a high percentage of the unsubstituted or less substituted aromatic compounds such as benzene, naphthaleue, methylnaphthalene, phenanthrene, and the like, and relatively small percentages of the highly alkyl substituted compounds. Furthermore, these unsubstitutedfor less substituted aromatic compounds have markedly different boiling temperatures and hence may be readily separated from one another by conventional means such as fractional distillation.

it is therefore an object of the invention to provide an improvement in coal hydrogenation processes whereby a product is obtained having a high proportion of highly aromatic and unsubstituted ring compounds, which may be readily separated from one another, because of their different boiling temperatures, by such methods asv fractional distillation. A further object of the invention is to provide a process whereby a coal hydrogenation product mixture, which contains substituted and par-` tially or fully hydrogenated ring compounds may be so altered that these compounds are converted to unsubstituted or less substituted aromatic compounds.

According to the process of our invention the above objects are achieved and a product is obtained which is rich in unsubstituted and methyl and ethyl substituted aromatic compounds by subjecting the liquid product of coal hydrogenation, including the pitch, to hydrogen pressure of more than 1000 pounds per square inch gauge at a temperature above 525 C. and in the absence of a catalyst. In the process of' the invention, which is of the hydrogenolysis type, the following reactions occur. The majority of the aliphatic hydrocarbons present in the feed are either aromatized or Cracked to gases. Hydrogenated ring structures are eliminated by aromatiza-v tion or ring opening. Alkyl substituents on the aromatic ring structures are cracked olf. The product of these reactions, therefore, is a greatly simplified mixture in that it contains no appreciable proportion of liquid aliphatic compounds and because the alkylbenzenes have been dealkylated toward benzene, the alkylnaphthalenes toward naphthalenes, and the other alkylated aromatics have been dealkylated in a similar manner.

Except under the most severe conditions, however, the product will contain appreciable proportions of toluene, xylenes, ethylbenzene and methylnaphthalenes, and a small proportion of more highly substituted compounds. Those distillation fractions of the product from which it might be diflicult to separate pure compounds may be recycled to the process.

Predominantly hydrocarbon mixtures which also contain some phenols and nitrogen bases may be subjected to the process of the invention without prior removal of the phenols and nitrogen bases. The phenolic compounds undergo dealkylation and dehydroxylation while the nitrogen bases are both dealkylated and deaminated. Thus it is possible to process raw product streams, reducing the gross mixture to one containing a relatively small number of simple aromatic components which can be separated one from another or into valuable fractions by known techniques. Thus the whole liquid product of coal hydrogenation may be processed, either as a Whole or as the separated raw light oil, raw middle oil, raw heavy oil or pitch or fractions thereof, without any necessity for first removing any phenols and nitrogen bases present.

The relative proportions of liquid and gaseous products resulting from the process of the invention depends in large measure on the type of material fed to the process. For example, coal hydrogenation neutral light oil contains about 30 percent by weight of aliphatic compounds, most of which are readily cracked to gases upon heating, and in the process of the invention the formation of additional gas results from the cracking olf of alkyl side chains from the aromatic compounds. Thus, after hydrogenolysis of coal hydrogenation neutral light oil according to the invention, there is about 50 percent by weight liquid yield and 50 percent by weight yield of gaseous products. The liquid recovery from coal hydrogenation middle oil, however, amounts to percent by weight or higher, for middle oil contains only a small proportion of aliphatic compounds, and the main reaction is dealkylation. Coal hydrogenation heavy oil and pitch contain practically no aliphatic compounds and hence the yield is almost all liquid plus, of course, some aliphatic gases from dealkylation reactions. The fact that an appreciable proportion of the total feed of coal hydrogenation whole liquid product is gasified does not mean a loss as far as value is concerned, however. The gases produced by the process of the invention comprise primarily methane, ethane and propane and constitute an excellent cracking stock for olefin production. They are readily recovered from the process for such utilization.

The efficiency of the process of the invention and the degree to which the various feed streams of coal hydrogenation products are converted to readily separated compounds rnay beunderstood more fully from a consideraf tion of the drawing.

In the drawing:

Fig. l is a graph of a distillation curve for a neutral light oil from coal hydrogenation which was used as feed in the process of the invention and a distillation curve for the product obtained after subjectingy the neutral light oil to the process of the invention.

Fig. 2 is a graph of a distillation curve for a raw middle oil from coal hydrogenation which was used as feed in the process of the invention and a distillation curve for the product obtained after subjecting the raw middle oil to the process of the invention.

Fig. 3 is a graph of distillation curves for the neutral fraction of a raw light oil from coal hydrogenation which was subjected to the process of the invention. The phenols and nitrogen bases were removed from a sample of the raw light oil feed and the neutral light oil remainder was distilled, the distillation curve being illustrated. After hydrogenolysis of the raw light oil according to the process of the invention, a sample of the neutral fraction of the product was separated and distilled and the distillation curve plotted is also illustrated in Fig. 3.

Fig. 4 is a graph of distillation curves for the phenol fraction of a raw light oil from coal hydrogenation which was subjected to the process of the invention. This is the same raw light oil as that of Fig. 3 and the phenol fraction of a sample of the raw light oil feed was separated and distilled, the distillation curve being illustrated in Fig. 4. Also illustrated in Fig. 4 is a distillation curve for a sample of the phenol fraction of the product resulting from the hydrogenolysis according to the invention of the coal hydrogenation raw light oil.

Fig. 5 is a graph of a distillation curve for a raw heavy oil from coal hydrogenation which was used as feed in the process of the invention and a distillation curve for the product obtained after subjecting the raw heavy oil to the process of the invention.

Inspection of the graphs of Figs. 1, 3 and 4 reveals clearly the change in proportions andV character of ther chemical constituents of the light oil during hydrogenolysis according to the process of the invention. In each case the distillation curve before hydrogenolysis is an almost smooth curve because of the proximity of the boiling temperatures of the various constituents. After the dealkylation, aromatization and similar conversions by the hydrogenolysis process of the invention, however, the curves have definite extended plateaus illustrating the high proportions of a relatively few compounds such as benzene, toluene, xylenes, ethylbenzene, naphthalene, phenol and cresols. When a coal hydrogenation light oil, as defined above, is subjected to hydrogenolysis according to the process of the invention, the total weight proportion of benzene, toluene, naphthalene and phenol is increased. Conversion of at least l5 percent by weight of the light oil to a mixture of benzene, naphthalene, toluene and phenol is achieved by the process of the invention and conversion of -as much as 45 percent by weight is possible. A further advantageous effect is the removal of aliphatic compounds, nearly all of which are cracked to gases. The light oil feed to the process may contain as much as 30 percent by weight or more of aliphatics, but the product will contain substantially none, less than one percent by weight. Yet another advantage of the process is the conversion of higher boiling phenols in the light oil fraction to more useful lower boiling phenols. By the process of the invention there is conversion of at least l5 percent of the phenolic compounds having boiling temperatures above 205 C. to phenolic compounds having boiling temperatures below 205 C., and conversion of as much as 40 percent is possible.

Heretofore, irrespective of factors of economy or convenience, no practical means has been known for separating useful products from coal hydrogenation middle oil, as defined above. This recovery is made possible, however, by the hydrogenolysis process of the invention, which has a three-fold effect on the raw middle oil. The hydrogenolysis causes extensive dealkylation of many of the compounds in the middle oil with the result that at least 25 percent by weight of these compounds are so dealkylated as to reduce their boiling temperature below 270 C., or into the light oil range. By the process of the invention there is conversion of at least l5 percent by weight of the middle oil into a mixture of benzene, toluene, phenol, naphthalene, uorene and phenanthrene, with a conversion of as muchV as 40 percent possible. These compounds are readily separated out by conventional methods such as distillation. Some of the components of the middle oil are aromatized to compounds having boiling temperatures above the middle oil range of 270 C. to 330 C. at atmospheric pressure, principally to phenanthrene, which is readily recovered by distillation. The compounds remaining in the middle oil temperature range after hydrogenolysis, principally uorene, have quite different boiling temperatures and may be readily separated by distillation. Fig. 2 of the drawing shows in detail the effect of hydrogenolysis on the distillation curve of the middle oil. It can be seen that many of the compounds have been converted to diierent compounds of higher or lower boiling temperature and that whereas before hydrogenolysis the distillation curve was smooth due to the proximity of the boiling temperatures of the components, after hydrogenolysis the plateaus of the individual compounds are seen, indicating their ready separability by distillation. The product contains less than 1 percent by weight of aliphatic compounds, though the feed may have contained 8 percent by weight or more.

When raw heavy oil from coal hydrogenations is subjected to hydrogenolysis according to the process of the invention at least one-quarter by weight of the components of the heavy oil are converted to compounds having boiling temperatures below 330 C. at atmospheric pressure, the lower boiling temperature limit of heavy oil. By the process of the invention the total weight proportion of benzene, toluene, naphthalene, phenol, phenanthrene, methylphenanthrene, pyrene and uoranthene in the heavy oil is increased by converting at least 20 percent by weight of the heavy oil to a mixture of these compounds. As much as 50 percent can be so converted.

Subjecting pitch derived frorn coal hydrogenation to the hydrogenolysis process of the invention results in the conversion of a substantial proportion of the pitch to chemical compounds having boiling point temperatures below the boiling point temperature range of pitch, as shown in Example V. At least 20 percent by weight of the pitch is converted to chemical compounds having boiling temperatures below 400 C. and as much as 40 percent can be so converted. Chemical compounds thus obtained from pitch include pyrene, uoranthene, phenanthrene, naphthalene and benzene.

The hydrogenolysis process of the invention may be operated either as a batch or continuous operation. For batch operation any suitable Vessel capable of withstanding the required pressure and capable of being heated to the necessary temperatures may be employed. Preferably, however, the process is carried out continuously. In the preferred embodiment a tubular reactor is employed. The tubular reactor must be capable of withstanding the pressures described below and there must be provision for maintaining the necessary temperature within the tube. The length of the tubular reactor must be such as to provide the desired residence time when the desired throughput or velocity of reaction is ernployed. In such a tubular reactor the hydrogen under high pressure and the feed are continuously passed into one end of the reactor and the product is withdrawn continuously from the other end. Four operation factors aifect the process. These are temperature, pressure, residence time of the feed in the reactor and the mol ratio ofV hydrogen to feed.

It is essential to the process that the temperature in the reactor be at least 525 C. The process can be operated at temperatures up to 700 C. or more, with a temperature between 550 C. and 650 C. being preferred. In general, the higher the temperature at which the process is operated, other variables being constant, the greater the simplicity of the product. That is to say, the product will be simpler in that it will have a higher proportion of unsubstituted aromatic compounds. For example, in the processing of a neutral light oil hydrocarbon fraction having a boiling temperature range of from C. to 260 C., and with the process operated under a pressure of 3000 pounds per square inch gauge, with a mol ratio of hydrogen to feed of 7.8 to 1, and with residence time of 5.0 minutes, the effect of temperature was as follows. Benzene, toluene, and naphthalene, which together accounted for only 6.1 percent by weight of the feed, constituted 24.1 percent by weight of the liquid product when the process was operated with a temperature of 550 C., 66.5 percent by weight with a temperature of 575 C. and 76.6 percent by Weight with a temperature of 600 C.

The pressure within the reactor for the process must be maintained above 1000 pounds per square inch gauge. A pressure of from 2000 to 3500 pounds per square inch gauge is preferred. In general, the higher the pressure under which the process is operated, other variables being constant, the greater the simplicity of the product. That is to say, the product will be simpler in that there will be a high proportion of unsubstituted aromatic compounds. For example, inthe processing of a neutral light oil hydrocarbon fraction having a boiling temperature range of from 100 C. to 260 C. and with the process operated at a temperature of 575 C. with a mol ratio of hydrogen to feed of 7.8 to 1, and with a residence time of 4.9 minutes, the effect of the pressure was as follows. Benzene, toluene and naphthalene, which together accounted for only 6.1 percent by weight of the feed, constituted 41.1 percent by weight of the liquid product when the process was operated under a pressure of 1000 pounds per square inch gauge, 42.6 percent by Weight with a pressure of 2000 pounds per square inch gauge and 66.5 percent by weight with a pressure of 3100 pounds per square inch gauge.

In general, other variables being constant, the longer the residence time the greater the simplicity of the product, as defined above. The intensity of this elfect diminishes, however, as the residence time increases. Although longer residence times may be employed if desired, a residence time of less than minutes is preferred for practical operation. For example, in the processing of a neutral light oil hydrocarbon fraction having a boiling temperature range of 100 C. to 260 C., and with. the process operated at a temperature of 575 C., under a pressure of 3200 pounds per square inch gauge and with a mol ratio of hydrogen to feed of 3.9 to 1, the eifect of residence time was as follows. Benzene, toluene and naphthalene, which together accounted for only 6.1 percent by weight of the feed, constituted 12.3 percent by weight of the liquid product after a residence time of 1.0 minutes, 21.7 percent after 5.5 minutes, 26.1 percent after 6.9 minutes and 28.5 percent after 10.0 minutes.

The mol ratio of hydrogen to feed is another factor of major importance in the operation of the process of the invention. To determine this ratio in the invention the molecular weight of the feed is employed. As used herein the term molecular weight is a number representing the average molecular weight of the feed. In the present work this number was estimated from the boiling range and composition of the feed stock in question. lf desired, it may be determined by other known techniques, such as the vapor-density method or the cryoscopic method. To insure an adequate proportion of hydrogen for the hydrogenolysis reaction it is essential that the mol ratio of hydrogen to feed be at least 2 to 1 and preferably 4 to 1 or higher. Above 2 to 1, with other variables being held constant, increases in the mol ratio of hydrogen to feed result in a more simplified product, as deiined above. Mol ratios of greater than to 1 are not recommended because the relatively slight increase in simplicity in product thereby obtained is not great enough to compensate for the increased cost of the added hydrogen. The preferred range for this ratio is between 4 and 20 mols of hydrogen per mol of feed. The effect on the product obtained of increasing the ratio can be seen from the following. ln the processing of a neutral light oil hydrocarbon fraction having a boiling temperature range of 100 C. to 260 C. and with the process operated at a Y temperature of 575 C., under a pressure of 3100 pounds per square inch gauge and with a residence time of 5 minutes, changes in the mol ratio of hydrogen to feed produced these results. Benzene, toluene, and naphthalene, which together accounted for only 6.1 percent by weight of the feed, constituted 34.8 percent of the product after operation with a hydrogen to feed mol ratio of 3.4 to 1, 46.6 percent with a mol ratio of 6.0 to l and 66.5 percent with a mol ratio of 7.9 to 1.

Example I There was obtained by the hydrogenation of coal a product fraction having a boiling temperature range of 114 C. to 260 C., from which the acidic and basic components had been removed. Such a fraction is known as a neutral light oil. This fraction was subjected to the process of the invention in a continuous operation. The apparatus used consisted of a reactor coil of 20 feet of high pressure tubing. The tubing, which had an effective volume of about 100 cubic centimeters, was immersed in a lead bath whereby the reactor tube was heated. The neutral light oil and hydrogen gas were passed continuously into the reactor tubing in the ratio of 7.9 mols of hydrogen per mol of oil. The residence time in the reactor tube for the reactants was 5.0 minutes. The pressure in the reaction tubing was 3100 pounds per square inch gauge and the temperature was 575 C.

The neutral light oil feed to the reactor contained no benzene, 0.7 percent by weight toluene, and 5.4 percent naphthalene, and none of the components of the feed could be separated therefrom by any economical method. After hydrogenolysis by the process of the invention the liquid recovery was 50 percent by Weight. The liquid product contained, by weight, 22;7 percent benzene, 16.7 percent toluene and 27.1 percent naphthalene, for a total of 66.5 percent by weight recovered as high purity compounds by simple fractional distillation. Another 11.3 percent by weight of the liquid product was found to be mixed Xylenes and ethyl-benzene and 3.6 percent was mixed methylnaphthalenes. The boiling temperature ranges of the feed and liquid product in relation to the volume are shown graphically in Figure 1 of the drawing.

The gas recovered from this run of the process contained, on a hydrogen-free basis, by Weight, 41 percent methane, 35 percent ethane, 17 percent propane and some higher molecular weight aliphatic hydrocarbons.

Example Il There was obtained by the hydrogenation of coal a product fraction known as raw middle oil and having a boiling temperature range of 260 C. to 330 C. This fraction was subjected to the process of the invention in a continuous operation. The apparatus used consisted of a reactor coil of 20 feet of high pressure tubing, the tubing having an inside diameter of one-quarter inch. The coiled tubing, which had an effective reaction volume of about 100 cubic centimeters, was immersed in a lead bath whereby the reactor tube was heated. The raw heavy oil and hydrogen gas were passed continuously into the reactor tubing in the ratio of 8 mols of hydrogen per mol of oil. The residence time in the reactor tube for the reactants was 2.0 minutes. The pressure in the reactor tubing was 3000 pounds per square inch gauge and the temperature was 600 C.

The raw middle oil feed to the reactor contained hydrocarbons, phenols and nitrogen base. The hydrocarbon fraction was separated from a sample of the feed and it was found that the boiling temperatures within the fraction were so close to one another that none of the components could be separated therefrom by any economical method. After hydrogenolysis by the process of the invention the liquid recovery was percent by Weight. The hydrocarbon and phenol fractions were separated from the product. Of the hydrocarbon fraction, 58 percent by Weight had been so reduced in boiling ternperatures as to be in the classification of light oil. The hydrocarbon fraction contained, by weight, 6.3 percent benzene, 5.0 percent toluene, 14.7 percent naphthalene, 5.9 percent fluorene and 10.5 percent pheuanthrene, all easily separated and purified. The boiling temperature ranges of the hydrocarbon fractions of the feed and of the product are shown graphically in Figure 2 of the drawing.

The phenols comprised 6.8 percent by weight of the liquid product. Of the phenols mixture thus obtained 41 percent by weight consisted of phenol, cresols, ethylphenols, and Xylenols, which could readily be distilled into fractions of commercial value. The gas recovered from this run of the process contained on a hydrogenfree basis, by weight, 49 percent methane, 39 percent ethane, l2 percent propane and some higher molecular weight aliphatic hydrocarbons.

Example III There was obtained by the hydrogenation of coal a product fraction known as raw heavy oil and having a boiling temperature range of 200 to 300 C. at a pressure of 60 millimeters of mercury. This fraction was subjected to the process of the invention in a continuous operation. The apparatus used consisted of a reactor coil of 20 feet f high pressure tubing, the tubing having an inside diameter of one-quarter inch. The coiled tubing, which had an effective reaction volume of about 100 cubic centimeters, was immersed in a lead bath whereby the reactor tube was heated. The raw heavy oil andl hydrogen gas were passed continuously into the reactor tubing in the ratio of 8 mols of hydrogen per mol of oil. The residence time in the reactor tube for the reactants was 1.0 minute. The pressure in the reactor tubing was 3000 pounds per square inch gauge and the temperature was 600 C.

After hydrogenolysis. by the process of the invention the'liquid recovery was 90 percent by weight. Thirty percent by weight of the liquid product boiled at temperatures below the boiling temperature range of the raw heavy oil feed. Analysis of the feed and of the liquid product showed that the concentrations of -a number of the important components of the feed were greatly increased, in most cases by 100 percent or more, by the process of the invention. Thus the Value of the raw heavy oil was increased by the process of the inventlon and these components, being present in much larger quantities, were much more easily recovered from the mixture. Illustrative was the increase in phenanthrene from 6 percent by weight in the feed to 15 percent by weight in the product and in the methylphenanthrenes from less than percent by weight in the feed to 10 percent by weight in the product. The proportion of liuoranthene was 3 percent by weight in the feed but was raised to 6 percent in the product. Likewise pyrene increased from 4 percent by weight of the feed to 7 percent by weight of the product. Example IV .There was obtained by the hydrogenation of coal a product fraction known as a raw light oil and having a boiling temperature range of 100 C. to 260 C. This fraction, containing hydrocarbons, phenols and nitrogen bases, was subjected to the process of the invention in a continuous operation. The apparatus used consisted of a reactor coil of 20 feet of high pressure tubing, the tubing having an inside diameter of one-quarter inch. The coiled tubing, which had an effective reaction volume of about 100 cubic centimeters, was immersed in a lead bath whereby the reaction tube was heated. The raw light oil and hydrogen were passed continuously into the reactor tubing in the ratio of 8.2 mols of hydrogen per mol of raw light oil. The residence time in the reactor tube for the reactants was 1.9 minutes. The pressure in the reactor was 3000 pounds per square inch gauge and the temperature was 600 C.

The raw light oil feed to the reactor consisted of 60.9 percent by weight hydrocarbons, 34.5 percent phenols and 4.6 percent nitrogen bases. Specifically, the raw light oil feed contained, by weight, 0.3 percent benzene, 1.0 percent toluene, 4.1 percent naphthalene and 4.0 percent phenol, none of which could be separated from the feed by any economical method. After hydrogenolysis by the process of the invention the liquid recovery was 68.0 percent by weight. The liquid product consisted, by weight, of 64.4 percent hydrocarbons, 30.5 percent phenols and 5.1 percent nitrogen bases. Specifically, the liquid product contained 11.0 percent benzene, 12.5 percent toluene, 15.6 percent napthalene and 14.6 percent phenol. Thus, while the raw light oil feed consisted by weight of a total of only 9.4 percent of these four valuable components, namely benzene, toluene, naphthalene and phenol, the liquid product of the process of the invention consisted of 53.7*percent by weight of these compounds, a percentage permitting ready recovery by conventional methods such as fractional distillation.

The beneiiciation of the raw light oil by the process of the invention, as exemplified in this example, may be further appreciated by reference to Figures 3 and 4 of the drawing. To obtain the graphs of these figures, sam- 10 plesjwere taken of both the feed and the product Iin the experiment of this example. These samples were then separated into three fractions, the phenols, the nitrogen bases and the hydrocarbon remainder or neutral light oil.v Distillation curves were then plotted for the hydrocarbons and phenol fractions. Figure 3 shows distillation curves for the neutral light oil fraction before and after hydrogenolysis by the process of the invention, while Figure 4 shows before and after curves for the phenols. From comparison of the two curves of each fraction it can readily be seen that the proportions of valuable constituents were greatly increased in each fraction, and their removal by ordinary fractional distillation was made possible.

Example V There was obtained by the hydrogenation of coal a product fraction which contained 57 percent heavy oil, 43 percent pitch and no light oil or middle oil. This fraction was subjected to the process of the invention in a continuous operation. The apparatus used consisted of a reactor coil of 15 feet of high pressure tubing, the tubing having an inside diameter of three-eighths inch. The coiled tubing, which had an effective reaction volume of 350 cubic centimeters, was immersed in a lead bath whereby the reactor was heated. The feed material and hydrogen gas were'passed continuously into the reactor tubing in the ratio of more than l0 mols of hydrogen per mol of feed. The residence time in the reactor tube for the reactants was 1.5 minutes. The pressure in the reactor tubing was 300 pounds per squareinch gauge and the temperature was 600 C.

After hydrogenolysis of the process of the invention the liquid recovery was 68 percent by weight, the remaining 32 percent consisting predominantly of gases and coke. Only 16 percent by weight of the recovered liquid was pitch; 58 percent comprised chemicals in the heavy oil range; 17 percent comprised chemicals in the light oil range and 9 percent comprised chemicals in the middle oil range.

Example VI There was obtained by the hydrogenation of coal a phenolic product fraction having a boiling temperature range of 114 C. to 260 C. and containing substantially all phenolic compounds. This fraction was subjected to the process of the invention in continuous operation. The apparatus used consisted of a reactor coil of 20 feet of high pressure tubing. The tubing which had an effective volume of about cubic centimeters, was immersed in a lead bath whereby the reactor tube was heated. The phenolic compound mixture and hydrogen gas were passed continuously into the reactor tubing in the ratio of 8.0 mols of hydrogen per mol of phenolic compounds. The residence time in the reactor tube for the reactance was l minute. The pressure in the reactor tube was 3000 pounds per square inch gauge and the temperature was 600 C. v

After hydrogenolysis by the proce-ss of the invention t-he liquid recovery was 8l percent by weight. It was determined lthat 28 percent of the phenols had been converted to hydrocarbons and water. The proportions o-f low-boiling phenols, those having boiling temperatures between 180 C. and 205 C., was increased from 32 percent by weight in the feed to 55 percent by weight in the phenolic product. The proportions of intermediate phenols, those having a boiling temperature range between 205 C. and 270 C., was decreased from 36 percent by weight in the feed to 25 percent by weight in the product. The proportions of high-boiling phenols, those having boiling temperatures between 230 C.' and 260 C. wasdecreased from 32 percent by weight in the feed to 19 percent by weight in the phenolic product. Theconcentration of phenol itself was increased from from 4.3 percent by weight in the feed to 22.0 percent' by weight in the phenolic product. There was a substantial increase in tbe proportion of meta-substituted phenols as a result of the process. This proportionate increase in meta-substituted phenols increased the reactivity of the mixture with formaldehyde, thereby causing the product to be a better raw material for the production of resins and plasticizers, and also facilitating the recovery of pure phenol.

What is claimed is:

1. A process applied to the products of coal hydrogenation which comprises intimately contacting a feed containing said products with gaseous hydrogen in the amount of at least two mols of hydrogen per mol of feed, said process being carried out in the absence of a catalyst, at a temperature of from 525 C. to 700 C. and at a pressure above 1000 pounds per square inch gauge, for no more than 15 minutes.

2. A process applied to the products of coal hydrogenatio-n which comprises intimately contacting a feed containing said productsv with gaseous hydrogen in the amount of from 4 to 20 mols of hydrogen per mol of feed, said process being carried out in the absence of a catalyst, at a temperature of from 550 C. to 650 C. and at a pressure of from 2000 to 3500 pounds per square inch gauge, for no more than-15 minutes.

3. A process applied to the whole liquid product of coal hydrogenation which comprises intimately contacting a feed containing said Whole liquid product with gaseous hydrogen in the amount of at least two mols of hydrogen per mol of feed, said process being carried out in the absence of a catalyst, at a temperature of from 525 C. to 700 C. and at a pressure above 1000 pounds per square inch gauge, for no more than 15 minutes.

4. A process applied to the light oil product of coal hydrogenation which comprises intimately contacting a feed containing said light oil with gaseous hydrogen in the amount of at least two mols of hydrogen per mol of feed, said process being carried out in the absence of a catalyst, at a temperature of from 525 C. to 700 C. and at a pressure above 100 pounds per square inch gauge, for no more than 15 minutes.

5. A process applied to the neutral light oil product of coal hydrogenation which comprises intimately contacting a feed containing said neutral light oil with gaseous hydrogen in the amount of at least two mols of lhydrogen per mol of feed, said process being carried out in the absence of a catalyst, at a temperature of from 525 C. to 700 C. land at a pressure above 1000 pounds per square inch gauge, for no more than l5 minutes.

6. A process applied to the middle oil product of coal hydrogenation which comprises intimately contacting a feed containing said middle oil with gaseous hydrogen in the amount of at least two mols of hydrogen per mol of feed, said process being carried out in the absence of a catalyst, at a temperature of from 525 C. to 700 C. and at a pressure above 1000 pounds per square inch gauge, for no more than minutes.

7. A process applied to the heavy oil product of coal hydrogenation which comprises intimately contacting a feed containing said heavy oil with gaseous hydrogen in the amount of at least two mols of hydrogen per mol of feed, said process being carried out in the absence of a catalyst, at a temperature of from 525 C. to 700 C. and at a pressure above 1000 pounds per square inch gauge, for no more than 15 minutes.

8. A process applied to the pitch product of coal hydrogenation which comprises intimately contacting a feed containing said pitch with gaseous hydrogen in the amount of at least two mols of hydrogen per mol of feed, said process being carried out in the absence of a catalyst, at a temperature of from 525 C. to 700 C. and at a pressure above 1000 pounds per square inch gauge, for no more than 15 minutes.

9. In a coal hydrogenation process wherein the major portion of the coal is converted to a liquid product having a boiling temperature range between 75 C. at atmos# pheric pressure and about 350 C. at a pressure of 50 mm. of mercury, said liquid product containing substantial quantities of alkyl substituted aromatic and cycloaliphatic compounds, the further improvement which comprises converting a majority of said alkyl substituted aromatic and cycloaliphatic compounds to unsubstituted and less substituted aromatic compounds by intimately contacting a feed containing said liquid product With gaseous hydrogen in the amount of at least two mols of hydrogen per mol of feed, said process being carried out in the absence of a catalyst, at a temperature of from 525 C. to 700 C. and at a pressure above 1000 pounds per square inch gauge, for no more than l5 minutes.

l0. In a coal hydrogenation process wherein a portion of the coal is converted to a light oil fraction having a boiling temperature range between 75 C. and 270 C. and consisting predominantly of aromatic compounds, substituted aromatic compounds and hydrogenated ring compounds, the further improvement which comprises converting at least l5 percent by weight of said light oil to a mixture of benzene, toluene, naphthalene and phenol by intimately contacting a feed containing said light oil fraction with gaseous hydrogen in the amount of from 4 to 20 mols of hydrogen per mol of feed, said process being carried out in the absence of a catalyst, at a temperature of from 550 C. to 650 C. and at a pressure above 1000 pounds per square inch gauge, for no more than 15 minutes.

1l. In a coal hydrogenation process wherein a portion of the coal is converted to a phenolic fraction having a boiling temperature range between 75 C. and 270 C. and consisting predominantly of phenolic compounds, the further improvement which comprises converting at least 15 percent by weight of the phenolic compounds in saidV fraction boiling at temperatures above 205 C. to phenolic compounds boiling at temperatures below 205 C., by intimately contacting a feed containing said phenolic fraction with gaseous hydrogen in the amount of from 4 to 20 mols of hydrogen per mol of feed, said process being carried out in the absence of a catalyst, at a temperature of from 550 C. to 650 C. and with a pressure above 1000 pounds per square inch gauge, for no more than 15 minutes.

12. In a coal hydrogenation process wherein a portion of the coal is converted to a middle oil fraction having a boiling temperature range at atmospheric pressure between 270 C. and 330 C. and consisting predominantly of aromatic compounds, substituted aromatic compounds and hydrogenated ring compounds, the further improvement which comprises converting at least one-quarter by Weight of said middle oil to compounds having a boiling temperature at atmospheric below 270 C. and converting at least 15 percent by weight of said middle oil to a mixture of benzene, toluene, naphthalene, phenol, fluorene and phenanthrene by intimately contacting a feed containing said middle oil fraction with gaseous hydrogen in the amount of from 4 to 20 mols of hydrogen per mol of feed, said process being carried out in the absence of a catalyst, at a temperature of from 550 C. to 650 C. and at a pressure above 1000 pounds per square inch gauge, for no more than 15 minutes.

13. In a coal hydrogenation process wherein a portion of the coal is converted to a heavy oil fraction having a. boiling temperature range at atmospheric pressure above 330 C. and consisting predominantly of aromatic compounds, substituted aromatic compounds and hydrogenated ring compounds, the further improvement which comprises converting at least one-quarter by weight of said heavy oil fraction to compounds having a boiling temperature at atmospheric pressure below 330 C. and converting at least 20 percent by lweight of said heavy oil to a mixture of benzene, toluene, phenol, naphtha- Iene, pyrene, phenanthrene, methylphenanthrene and fluoranthene, by intimately contacting a feed containing said heavy oil fraction with gaseous hydrogen in the amount of from 4 to 20 mols of hydrogen per mol of feed, said process being carried out in the absence of a catalyst, at a temperature of from 550 C. to 650 C. and at a pressure above 1000 pounds per square inch gauge, for no more than 15 minutes.

14. In a coal hydrogenation process wherein a portion of the coal is converted to a pitch comprised predominantly of condensed ring compounds having high boiling point temperatures, the further improvement which comprises converting at least 20 percent by weight of said pitch to compounds having boiling temperatures below 400 C., by intimately contacting a feed containing said pitch with gaseous hydrogen in the amount of from 4 to 20 mols of hydrogen per mol of feed, said process being carried out in the absence of a catalyst, at a temperature-of from 550 C. yto 650 C. and at a pressure above 1000 pounds per square inch gauge, for no more than 15 minutes.

References Cited in the tile of this patent UNTED STATES PATENTS 1,251,954 Bergius et al. Jan. 1, 1918 1,920,887 Pier Aug. 1, 1933 2,605,215 Coghlan July 29, 1952 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Nef, 2,913,397 November 1'7 1959 James V, Murray Jr. `et a3.o

It is hereby certified that error appears in the-printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Golem 9, line 28 for "fluoranthene" read we fluoranthrene me;

column lO, line 3l, for "BOO pounds read e SOOO pounds en; line 33, for "of the process" read e by the' process e Signed and sealed this 31st day of May 1960.,

(SEAL) Attest:

KARL H., AXLINE HUBERT C. WATSON Atteating Officer Commissioner of Patents

Claims

1. A PROCESS APPLIED TO THE PRODUCTS OF COAL HYDROGENATION WHICH COMPRISES INTIMATELY CONTACTING A FEED CONTAINING SAID PRODUCTS WITH GASEOUS HYDROGEN IN THE AMOUNT OF AT LEAST TWO MOLS OF HYDROGEN PER MOL OF FREED, SAID PROCESS BEING CARRIED OUT IN THE ABSENCE OF A CATALYST, AT A TEMPERATURE OF FROM 525* C. TO 700* C. AND AT A PRESSURE ABOVE 1000 POUNDS PER SQUARE INCH GAUGE, FOR NO MORE THAN 15 MINUTES.