US2319990A - Production of solvents - Google Patents

Description

PRODUCTION OF SOLVENTS Filed Aug. 14 1940 5w fue @muc/Mz: CAA/1455 szw/PFW@ CHA M55? Pf6/ouf l l www! wb Patented May 25, 1943 PRODUCTION OF SOLVENTS Jacquelin E. Harvey, Jr., Atlanta, Ga., assigner of one-half to Southern Wood Preserving Company, East Point, Ga., a corporation of Georgia Application August 14, 1940, Serial No. 352,671 1 claim. (o1. 19e- 53) The present invention relates to the production of valuable liquids from tars of aromatic content and fractions thereof, crude and/or refined.

An object of the present invention is the sube jection of tars of aromatic content and fractions thereof, crude and/or refined, to the action of hydrogen in step-wise manner, whereby to provide solvents of increased solvency, said solvents being characterized when compared to an intermediate sta'rting material of the process, by a fractional increment in the low boiling range in excess of fractional increment in the higher 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.

Starting materials of the present invention include tars and fractions thereof derived from coal, 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; as for instance tars of aromatic content derived from coal and fractions thereof; tars produced by cracking hydrocarbons; tars resulting from the' action of hydrogen on hydrocarbons; tars resulting from polymerization; high boiling extracts of carbonaceous substances; high boiling hydrocarbons of aromatic content having olefinic and/or naphthenic content.

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 W boiling fractions from the starting material, high boiling fractions and pitches. Starting material previously subjected to the action of hydrogen are suitable.

Especially suitable as starting material is high Cil temperature coke oven tar which is available in` Y 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 mannen'to the controlled action of hydrogen whereby to produce solvents having. enhanced solvency, and as compared to the intermediate parent material, an increment of fractions in the low boiling range in excess of fractional increment in the higher boiling range,

, a specific gravity of in the order of 1.06, and

substantially 25% residue above 355 C., is subjected to the action of hydrogen at 385 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 explained. The creosote of lowered sulfur content is then passed in liquid phase through a high pressure reaction vessel while simultaneously iiowing hydrogen therewith in the presence of a molybdenum oxide catalyst at a temperature of 400 C. and 350 atmospheres pressure. The time of contact is one hour 'and the flow of gas 15,000 cubic feet per barrel refined creosote. The beneciated creosote upon inspection Will be found to have a lowered boiling range, specific gravity, coke residue and viscosity. Solvency in some of the lower fractions of the' beneciated creosote will be reduced as compared to solvents extant of comparable boiling range.

The beneciated creosote is stripped to an up-` per 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 in coordination with other process variables is so controlled as to induce a solvent having increased solvency and an increment of fractions' in the lower boiling range in excess of fractionalincrement/ lof fraction in the higher boiling range.-

The solvent so produced may be fractionated to provide rened solvents of lowered corrosivity of any boiling range within the limits of the immediate parent material, as for instance:

Degrees centigrade Benzol 78-120 Toluol -150 Hi-lash naphtha -200 Heavy naphtha 150-290 Plasticizers -360 or others.

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

In the foregoing example 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 in the presence of an oxide kcatalyst whereby to produce an intermediate product of lowered solvency, specific gravity, boiling range, coke residue and viscosity; stripping from the beneciated material a low boiling fraction thereof and subjecting at least a portion of low boiling ends to the controlled action of hydrogen whereby to enhance solvehCy, and produce as compared to the immediate starting material, an

increment of fractions in the lower boiling rance in excess of fractional increment in the higher boiling range, 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 tars of aromatic content, and fractions thereof, with hydrogen in step-wise manner whereby to produce refined Solvents of lowered corrosivity, said solvents beine characterized by increased solvency as compared to their immediate starting material as heretofore disclosed. The step-wise action of hydrogen is characterized rst by providing hydrogen in levv that depolymerizes ring multiplicities thereby inducing lowered specific gravity, coke residue, boiling range, solvency and viscosity, and last, by providing hydrogen in flow that, among other things, increases solvency.

The aforenamed step-Wise action of hydrogen thus provides a method for securing refined solvents of lowered corrosivity from heavy or high boiling hydrocarbons of aromatic content, said high boilers characterized by the presence of ring multiplicities of great thermal susceptibility.

Example HA sulfur containing coal tar, specic gravity 1.1641, a coke residue in excess of 5%, and in excess of 35% boiling at 355 C. is subjected to the action of hydrogen at 380 C. and 200 atmospheres pressure for such a length of time as to lower sulfur content, the while precluding substantial induction of low boiling ends. The coal tar of lowered sulfur content is then passed in liquid phase through a high pressure reaction chamber while simultaneously flowing therewith hydrogen at a pressure of 300 atmospheres and a temperature of 410 C.; time of contact is one hour, catalyst vanadium oxide, and ilow of hydrogen 15,000 cubic feet per barrel feed stock. The thus treated coal tar is found to have a lowered specific gravity, viscosity, and coke residue. In some of the fractional parts of the treated coal tarthere will be lowered solvency as compared to solvents extant of comparable boiling range.

The beneficiated tar is then stripped to an upper limit of 360 C. and the low ends thereof subjected to the action of a flow of hydrogen at 4509 C. and 200 atmospheres pressure for such a length of time as to increase solvency and produce an increment of fractions, as compared to the immediate starting material, in the lower boiling range in excess of fractional increment in the higher boiling range, thus providing the refined solvent of the present process.

Example 3.A high boiling coal tar fraction of sulfur content, initial boiling D Oint of substantially 245 C. is subjected to the action of hy` drogen at 375 C. and 250 atmospheres pressure for such a length of time as to reduce sulfur content. 'Ihe coal tar of reduced sulfur content is then passed in liquid phase through a high pressure reaction chamberwhile simultaneously flewing hydrogen therethrough at a temperature of 410 C. and 300 atmospheres pressure; the catalyst is molybdenum oxide and flow of hydrogen so controlled as to induce no substantial percentage of coke in the reaction chamber, nor percentage of chain structures as to preclude final solvent production as stated.

- Upon inspection the beneilciated coal tar frection will be found to have a lowered specific grav- Y, ity, coke residue, boiling range and viscosity, and,

in the case of some fractional parts of the beneficiated material a lowered solvency as compared to solvents extant.

The beneciated material is stripped at 290 C. and the distillate subjected to the action of hydrogen at 450 C. and 200 atmospheres pressure, flow of hydrogen 5,000 cubic feet per barrel feed and the time so controlled as to providean increment of low boiling fractions inexcess of fractional increment in the higher boiling range. The solvency of the finally processed material is in excess of the solvency of the immediate starting material. `The time in the last step may be a fractional part of a minute or more.

The residue incidental to the stripping steps may be recycled or used as an article of commerce of enhanced value, as for instance binders, plasticizers or the like.

The starting material of high carbon content, as for instance coke oven tar is characterized by. in its raw state, such a percentage or high mo1eeular complexes or polymerized products that the refined solvents of the present invention are not possible of manufacture therefrom directly, but must be produced in step-wise manner, as heretofore explained, whereby among other things, the action of hydrogen depolymerizes 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 low ends whereby to provide the intermediate parent material of the refined solvents of lowered corrosivity, said rened solvents beingA characterized, as compared to the immediate starting material, by an increment of fractions in the lower boiling range in excess of fractional increment in the higher boiling range; the residue incidental to said stripping may, because of its depolymerized or partially depolymerized condition serve as recycle material to the end that conversion of the starting material in the percentage nally remaining liquid approaches volume for volume of the starting material into the refined solvents of the present invention.

In the conversion of starting material, partially or approaching unity, into the refined solvents of lowered corrosivity, 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 0f, and incidental to, the present invention. Temperatures are preferred that cause no substantial amount of coking.

Gas flows are usually held in excess of 2,000 cubic feet per barrel feed treated. In the stepwise application of hydrogen a few trials when using any of the starting materials will determine the gas flow when coordinated. with' the selected temperature and pressure conditionsto effect said depolymerization.'v 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.

i Concerning the gas iioW that' increases solvency and provides an increment of low boiling fractions in excess of fractional increment in the higher boiling range, said gas flow is held at that point which induces no percentage of final liquid chain structures that would preclude the enhanced solvents of the present invention; For a given coordination of temperature and pressure, the gas ow in the last instance is lower than the gas ow in the preceding instance.

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

Viewed broadly the hydrogen flow in the instance of obtaining depolymerizing conditions may be lower than 10,000 cubic feet per barrel feed, and the flow in the last instance is held at that point that increases solvency.

In the hydrogen action that reduces sulfur content, the action of hydrogen may be effected in an intermittent autoclave or in a continuous plant, and in the event of continuous practice, the gas flow is maintained so as to assist in sulfur reduction and the removal thereof from the reaction zone, 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 of the present process,

By the term beneflcated as used herein and in the appended claim 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 fur.- ther processing, substitutes for the boiling ranges of benzol, toluol, xylol, the various naphthas and the various plasticizers.

Thus, the depolymerized starting material may be cut according to the need at hand, said out then being subjected to the action of hydrogen that increases solvency as heretofore explained.

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, howevery dicultly reducible oxides are preferred. The catalyst in any form may be employed, as for instance pellets, comminuted, supported on carriers or the like; in any effective form.

If desired, comminuted catalyst 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 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 1nvention,'it may be desirable Yprior tothe 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. Refractory solvents are desirable, but others more susceptible to the reactions inherent' inv and to the present process are usable. T

Concerning solvents, it may be said that tar Y in itself, as for instance 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.l

' The action of hydrogen may be effected inone or more cyclesor in one or several chambers, with or without releasing the pressure, and with or without variation of process controls.

Various modes of practicing the present invention are possible, as 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. 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 reaction chamber, a series thereof, a parallelism thereof including a multiplicity thereof.

The refined solvent of the present invention may 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 or others, 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 sulfides 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.

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.

The term pitch as used herein includes the higher boiling fractions of tar, in other Words tar from which low boiling ends have been removed, such low boiling ends being suitable per se as creosote, other wood preservative, or solvent. For instance the nal residue resulting from evaporating tar to dryness or substantial dryness (coke or hard pitch) and then stripping Wood preservative from the distillate is a very suitable pitch for use as a starting material of the .present process. Minor changes may be made within the scop of the appended claim without departing from the vspirit of the invention.

I claim: l In the production of solvents from a mixture of sulfur-bearing high temperature coil 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 ow of hydrogen whilst contacting as catalytic material an oxide of a metal, said hydrogen ow being selected from the range fractions in the lower boiling range in excess of fractional increment in the higher boiling range by subjecting said stripped low boiling material to the action of a relatively low flow of hydrogen, a temperature and pressure of at least 300 C. and 50 atmospheres, respectively, to produce a solvent.

JACQUELIN E. HARVEY, J n.

1 CERTIFICATE 0E CORRECTION. Patent No. 2,519,990. May 25, 19.1.5.

JACQUELIN E. HARVEY, JR.

It is hereby certified that error appears in the printed specification of the above nmbered patent requiring correction as follows; Page l, first column, line 56, .after the word "removed" insert aperiod; second column, line 51T, for "50o c." read --5000 0.--, line lia, for "fraction" read --fractons--g page 5, second column, line l1, strike out "in"^; and that the said Letters -Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office. v

Signedand sealed-this 6th day of July, A. D. 1914.5.

` Henrr Van Arsdale, (Seal) Acting Commissioner of Patents.

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