US2319988A - Production of solvents - Google Patents

Description

May 25 1943 J. E.y HARVEY, JR 2,319,988

PRODUCTION OF SOLVENTS Filed Aug'. 14, 1940 Patented May 25, 1943 UNITED STATES PATENT OFFICE PRODUCTION OF SOLVENTS Application August 14, 1940, serial No. 352,669

1 Claim.

The present invention relates to the production of valuable liquids from tars and fractions thereof, crude and/or refined.

An object of the present invention is the subjection of tars and fractions thereof, crude 'and/ or rei-ined, to the action of hydrogen in step-wise manner, whereby to provide refined solvents of increased solvency and boiling range.

A further object of the present invention is the production of refined solvents of lowered corrosivity, the characteristics of which are, among other things, dependent upon hydrogen supply, as hereafter explained.

Other objects of the present invention will be apparent from the following disclosures.

Suitable starting materials of the present invention include tars and fractions thereof of aromatic content derived' from coal and petroleum and gas or gases of carbon content, as for instance coke oven tar, water gas tar, gas house tar, and tars of aromatic content in general, tars produced by cracking hydrocarbons; tars resulting from the action of hydrogen on hydrocarbons; tars resulting from polymerization; high boiling aromatic extracts of carbonaceous substances; high boiling hydrocarbons of 'aromatic content having olenic and/or naphthenic content.

Especially attractive as starting material is high temperature coke oven tar and fractions thereof which is available in large quantities at low prices.

The present invention may be viewed broadly as a process for the production of refined solvents of lowered corrosivity by subjecting the starting material, in step-wise manner, to the controlled action of hydrogen whereby to produce said solvents having increased boiling points and enhanced solvency.

The invention will be understood from the following description of illustrative steps comprising various methods of securing the objects of the invention, when read in connection with the accompanying drawing wherein the ligure is a diagrammatic sketch of an apparatus for carrying out a form of the process of the invention and wherein the nature of the step carried out in each chamber and the contents thereof are indicated by legend.

Example 1.-A sulfur bearing coal tar creosote, characterized by in excess of 1% coke residue, a specic gravityof in the order of 1.05, and substantially 215% residue abovel 355 C. is subjected to the action of hydrogen at 375 C. and 200 atmospheres pressure whereby to lower sulfur content, thereby lowering corrosivity, at least providing for lowered corrosivity in the finished material as hereinafter described, the while inducing no substantial percentage of low boiling ends. The creosote of lowered sulfur content is passed in liquid phase through a high pressure reaction .s no

vessel while simultaneously fnowingl, hydrogen therewith in the presence of a molybdenum oxide catalyst at a temperature of 400 C. and 250 atmospheres pressure. The time of contact is one hour and the ow of gas 15,000 cubic feet per barrel refined creosote. The beneficiated creosote upon inspection will be found to have a lowered boiling range, specific gravity and viscosity. Solvency in some of the lower fractions of the beneficiated creosote will be a lowered quantity as compared to solvents extant of a comparable boiling range.

The beneciated material is stripped to an upper limit of 300 C. and the distillate is passed through a high pressure reactor at 455 C. and 200 atmospheres pressure while contacting a molybdenum oxide catalyst. The flow of hydrogen is controlled at 3000 cubic feet per barrel material thereby inducing a solvent having, as compared to the intermediate starting material, increased boiling points and increased solvency.

The solvent so produced may be fractionated to provide refined solvents of lowered corrosivity of any boiling range within the limitations of the nally processed material, as for instance:

Degrees centigrade Benzol '78-120 Toluol 1GO-150 Hi-flash naphtha 150-200 Heavy naphtha 150-290 Plasticizers i60-360 or others.

VThe rened solvents of lowered corrosivity serve as substitutes for the commercial solvents noted.

In the foregoing examples, it will be noted that the present process` provides a method for contacting the starting material with hydrogen whereby to lower sulfur content, thereafter, contacting the material of lowered sulfur content with hydrogen while contacting an oxide catalyst whereby to produce an intermediate product of lowered solvency, specic gravity, boiling range and viscosity; stripping from the beneiiciated material a fraction thereof and subjecting at least a portion of the distillate to the controlled action of hydrogen whereby to enhance solvency and increase boiling points thus providing the refined solvent of lowered corrosivity of the present invention.

Looked at in one manner, the present process provides a method for treating sulfur bearing ters of aromatic content, and fractions thereof, with hydrogen in step-wise manner whereby to produce refined solvents of lowered corrosivity, said solvents being characterized by increased solvency and boiling points when compared to the intermediate parent material, as above disclosed.

of hydrogen depolymerizes, at least to a degree, said molecular complexes contained in the starting material.

The depolymerized or partially depolymerized tar or fractions thereof of lowered sulfur content is then stripped of a percentage of its newly in- The aforenamed step-wise action of hydrogen ring multiplicities of great thermal susceptibility. Example 2 A sulfur containing coal tar,

`high boilers characterized by the presence of specific gravity 1.1641, a coke residue in excess of 5%, and in excess of 35% boiling at 355 C. is subjectedto the Aactionof hydrogen at 360 C. and 200 atmospheres pressure for such a length of time as to lower sulfur content. The coal tar of lowered sulfur content is passed in liquid phase through a high pressure reaction chamber while simultaneously flowing hydrogen therewith at a pressure of 300 atmospheres and a temperature of 420 C. Time of contact is one hour, catalyst vanadium oxide, and flow of hydrogen `12,000 cubic feet per barrel feed stock. The thus treated coal tar is found to have an overall lowered specific gravity, viscosity and coke residue, and in some of its fractional parts a lowered solvency as compared to solvents extant. The beneflciated tar is then stripped to an upper limit of 360 C. and the distillate subjected to the action of a ow of hydrogen at 450 C. and 225 atmospheres pressure, withV the time of contact and gas flow so controlled as to increase boiling points and solvency. YThe flow of gas in this instanceis chosen from between 2500 and 3500 cubic feet per barrel feed stock.

Example 3,-A high boiling coal tar fraction of sulfur content, initial boiling point of substantially 250 C. is subjected to the action of hydrogen at 375 C. and 300 atmospheres pressure for such a time as to reduce sulfur content, the while inducing no substantial percentage of lowboiling fractions. The coal tar'of reduced sulfur content is then passed in liquid phase through a highpressure reaction chamberY while simultanously owing hydrogen therethrough at a temperature of 410 C. and 300 atmospheres pressure; catalyst, molybdenum oxide. Upon inspection the beneficiated coal tarfraction will be found to have a lowered specific gravity, viscosity, coke residue, boiling range, and, in the case of some fractional parts of the beneflciated material a lowered solvency as compared to solvents extant.

Ihe beneficiated material is stripped to 290 C. and the distillate subjected to the action of hydrogen at 450 C. and 300 atmospheres pressure; flow of hydrogen 2,500 cubic feet per barrel feed and the time so controlled as to increase boiling points and solvency. The time in the last step maybe a fractional minute or more, as for instance several minutes.

The residues incidental to the stripping actions aforenamed may be recycled or used as an article of commerce of enhanced value, as for instance binders or the like.

The starting material of high carbon content, as for instance, high temperature coke oven tar in its raw state, is characterized by such a perduced low ends whereby to provide the interjmediate parent material of the refined solvents of lowered corrosivity said refined solvents characterized by increase of boiling points and solvency; the residue incidental to said stripping may, because of its depolymerized or partially depolymerized conditions serve as recycle material to the end that conversion of the starting material in the percentage remaining nally liquid approaches volume for volume of the starting material into the refined solvents of the present invention.

In the conversion of starting materials, partially or approaching unity, into the refined solvents of lowered corrosivity of the present invention temperatures as low as 300 C. may be employed; pressures as low as 50 atmospheres may be used. However, temperatures and pressures of an increased range provide better commercial practice. The time element is desirably that period which affords commercial recoveries of the products of, and incidental to, the present invention. Temperatures are preferred that cause no ccking.

Gas flows are usually held in excess of 2,000 cubic feet per barrel material treated, as for instance 2,500 cubic feet or above. In the stepwise application of hydrogen a few trials when using any of the starting materials will determine the gas ow, when coordinated with the selected temperature and pressure conditions to effect said depolymerizing. The gas flow in this instance may be a variable quantity because of the varying ranges of coordinated temperature and pressure that may be selected. When using any chosen coordination of temperature and pressure, a few trials will readily determine the gas flow that provides depolymerizing conditions to the end that solvency, specific gravity, viscosity and boiling range are lowered.

Concerning the gas ow that increases boiling range and solvency, said gas ow is held at that point that increases boiling range and solvency thus providing the refined solvent of lowered corrosivity of the present invention. A few trials with any of the intermediate starting materials under chosen coordination of temperature and pressure will readily determine the desirable gas ow. For a given coordination of temperature and pressure, the gas ow in the last instance is lower than the gas flow in the preceding instance.

Using some starting materials, a gas ow of 10,000-15,000 cubic feet per barrel, or higher, has proven satisfactory for depolymerizing conditions, and, gas flow in the order of 6,000-8,000 or lower when increasing solvency, and boiling points has proven satisfactory.

In the hydrogen action that reduces sulfur content, the action of hydrogen may be effected in an autoclave or in a continuous plant, and in the event continuous practice is used, the now of gas is maintained so as to assist in reduction of sulfur content, the while inducing no substantial percentage of carbon, low boiling fractions or percentages of liquid chain structures that would preclude the provision of the refined solvents of superior solvency as stated.

By the term beneciated as used herein and in the appended claims is meant the starting material at least once subjected to the action of hydrogen in accordance with the present process.

After the starting tar has been subjected to depolymerizing action, the stripping step may be effected at any point selected within a wide range to provide a cut capable of providing, after further processing, substitutesI for the boiling range or ranges of benzol, toluol, xylol, naphthas, and/or plasticizers.

Thus, the depolymerized starting material may be cut according to the need at hand, said cut being then subjected to the action of hydrogen that increases solvency and boiling points.

The catalysts of the present invention are oxides; as for instance oxides of metals of the 6th and 8th periodic groups; the oxides of other groups may be used, however, diflicultly reducible oxides are preferred. The catalyst in any form may be employed, as for instance pellets, comminuted, supported on carriers or the like.

If desired, comminuted catalysts may be used in the hydrogen step characterized by depolymerization; and in the step characterized by solvency increase, a rigid catalyst may be used.

By the term multiplicity of rings, high molecular complexes and polymerized products are meant high boiling fractions of aromatic content, a portion of which at least may be viewed as ring multiples; or said terms, any or all, may be used to describe high boiling fractions of the starting material which because of high carbon content are especially susceptible to thermal degradation.

When subjecting high boiling fractions of the starting material to the process of the present invention, it may be desirable prior to the depolymerizing step, or the sulfur reduction step, to at least partially depolymerize the molecular complexes by use of a solvent. Said solvent may be added in a small amount, or up to volume for volume or more may be used. Refractory solvents may be desirable, but others more susceptible to the reactions inherent in and to the present process are usable.

Concerning solvents, it may be said that tar itself, as for instance high temperature coke oven tar, is constituted of high molecular complexes dissolved, cut back or depolymerized with a solvent, said solvent being the .lower boiling fractions of said tar.

The action of hydrogen as aforestated may be eifected in one or more cycles or chambers, with or without releasing the pressure and with or without variation of process controls, including changes in either temperature, pressure and/or gas ow.

Various modes of practicing the present invention are possible; for instance the depolymerized starting material may be stripped as for instance by gas movement; the low ends thus stripped may then, with or without releasing pressure, be subjected to the further action of hydrogen that increases solvency and boiling points. Or the desired stripped material may be obtained by partial release of pressure which would correspond to the fractional recovery desired or predetermined.

The process may be practiced in an autoclave and/or a single high pressure reaction chamber, a series thereof, a parallelism thereof, including a multiplicity thereof.

The refined solvent of the present invention characterized by lowered corrosivity and superior solvency may, as aforestated, be fractionated to provide solvents and/or plasticizers of various boiling ranges, and in the instance Where solvents are processed from a deep cut on the depolymerized material, the highest boiling fraction thereof may serve as a substitute for certain plasticizers.

In the first cycle of hydrogen action that reduces sulfur content, said reduction of sulfur may be accomplished in the presence of a catalyst. Catalysts effective in the presence of hydrogen are usable, as for instance the oxides and/or suliides of molybdenum, vanadium, uranium, cobalt, tin, manganese, tungsten, or the like.

In the disclosures herein made the removing of low boiling fractions by gas movement or pressure release is considered the equivalent of distillation.

When reference is made to high molecular complexes contained in the starting material, and when the starting material contains low boiling fractions that are not considered high molecular complexes, it is of course obvious that the high molecular complexes contained in the starting material are to a certain extent depolymerized by the solvent present.

Starting materials of the present process also include tars of aromatic content from which low boiling fractions have been removed, as for instance tars from which solvent oils have been removed. Viewed broadly, the starting materials of the present process are tars of aromatic content, fractions of said tar more viscous than the starting material due to removal of low boiling fractions, high boiling fractions and pitches.

It will be seen that by reduction of sulfur content of the material under treatment during any stage of hydrogen action, the oxide catalyst used during subsequent stages is at least partially protected from the effect of the sulfur.

Minor changes may be made Within the scope of the appended claim without departing fro the spirit of the invention.

I claim:

In the production of solvents from a mixture of sulfur bearing high temperature coal tar fractions, the process which comprises: subjecting said tar fractions to the action of hydrogen with time, temperature and pressure so controlled as to reduce sulfur content; subjecting said tar fractions of lowered sulfur content to the action of a relatively high flow of hydrogen whilst contacting an oxide catalyst, said hydrogen ow being selected from the range above 10,000 cubic feet per barrel material treated, at a pressure of at least about 250 atmospheres, and a temperature of at least 400 C.; carrying on the process for such a length of time as to provide a material of lowered specific gravity and viscosity; stripping low boiling fractions from the beneiiciated material; and increasing the boiling points of at least a chosen portion of said stripped fractions by subjecting same to the action of a relatively low flow of hydrogen not in excess of about 8,000 cubic feet per barrel material treated whilst maintaining a pressure and temperature not substantially lower than about 200 atmospheres and 450 C., respectively, to produce a solvent.

JACQUELIN E. HARVEY, JR.

Images