US2291323A - Production of solvents from coal tar - Google Patents

Description

July 28, 1942- J. HARVEY, JR 2,291,323

4 PRGDUCTION OF SOLVENTS FROM COAL TAR Filed July 13, 1940 /Wf/mr//Y CHA/1455 (CA mL yar: coa/ur @MPM/y0) Patented July 28, 1942 PRODUCTION OE' S'IOAIENTS FROM COAL J acquelin E. Harvey, Jr., Atlanta, Ga., assignor of one-half to Southern Wood Preserving Company, East Point, Ga., a corporation of Georgia Application July 13, 1940, Serial No. 345,438 2 Claims. (Cl. 196-53) The present invention relates to the production of valuable liquids from tars and fractions thereof, crude and/ or rened.

An object of the present invention is the subjection of tars and fractions thereof, crude and/or rened, to the action of hydrogen in stepwise manner, whereby to provide solvents of increased solvency and boiling range.

A further object of the present invention is the production of solvents, the characteristics of which are, among other things, dependent upon hydrogen supply.

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 derived from coal and petroleum, as for instance coke-oven tar, gas house tar, water gas tar and tars of aromatic content derived from petroleum or fractions thereof; tars produced by cracking hydrocarbons; tars resulting from the action of hydrogen or hydrocarbons; tars resulting from catalytic action n hydrocarbons, including polymerization; high boiling aromatic extracts of carbonaceous substances; high boiling hydrocarbons of olenic and naphthenic content; tars and fractions thereof of aromatic content.

Especially attractive as starting material is high temperature coke-oven tar which is available in large quantities at low price.

The present invention may be viewed broadly as providing a process for the production of solvents by subjecting the starting material, in step-wise manner, to the controlled action of hydrogen whereby to produce solvents of increased boiling range 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 thegure 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.

Erample 1.-A coal tar boiling substantially 3% at 2`10 C. waspassed through ahigh pressure reaction chamber at 400 C. and 200 atmospheres pressure; catalyst, molybdenum sulfide; time of contact, 1 hour and gas flow sufcient to provide a beneciated tar having a, lowered solvency, boiling range, specific gravity and viscosity. The thus beneciated tar was stripped to 315 C. and the distillate therefrom boiling:

The stripped material whose end point was substantially 315 C. was passed through a, high pressure reaction vessel at 475 C. and a pressure of 250 atmospheres with ow of hydrogen so controlled as to provide a solvent, as compared to its intermediate parent material, having increased boiling range, and solvency.

Example 2.-A residue from coal tar boiling substantially 3% at 380 C., Conradson carbon 14.5 and specic gravity 1.1208 was passed through a high pressure reaction chamber at 410 C. and 300 atmospheres pressure; time of contact 1 hour; catalyst, cobalt sulfide and gas flow suflicient to provide a beneficiated tar fraction having a specific gravity of 1.0625, a Conradson carbon of 4.89 and lower solvency than the starting product. The thus beneciated tar fraction was stripped to 350 C., the distillate therefrom boiling:

Per cent I. B. P.210 C 4. 6 210-235 C 0. 4 23E-270 C 4. 0 270315 C- 34.0 315-350 C 57.0

The stripped material whose end point was substantially 350 C. was passed through a high pressure reactor at 465 C. and 300 atmospheres pressure, while contacting a molybdenum-tin sulfide catalyst; ow of hydrogen so controlled as to induce a solvent having, as compared to the intermediate starting material, an increased boiling range and solvency.

The solvents so produced maybe fractionated to provide solvents and plasticizers of any boiling range, as for instance:

. C. Benzol 78-120 Toluol -150 Hi-flash naphtha -200 Heavy naphtha 150-290 Plasticizers -360 yfrom the controlled action of hydrogen that,

among other things, increases boiling range.

Looked at in. one manner, the present process provides a method for treating aromatic tars, or

fractions thereof, with hydrogen in step-Wise manner rwhereby to produce solvents,said solvents being characterized by increased solvency, and boiling range when compared to intermediate parent material, as heretofore disclosed. The said step-wise action f hydrogen being characterized by first providing hydrogen in flow that depolymerizes ring multiplicities thereby inducing lowered specific gravity, boiling range and solvency and second, by providing hydrogen in iiow that increases boiling range and solvency.

The aforenamed step-wise actionofhydrogen` thus provides a method for securing solvents of increased solvency and boiling range from heavy or high boiling hydrocarbons of aromatic content, said high boilers characterized by the presence of'ring multiplicities of great thermal susceptibility.

The starting materials of high carbon content, as for instance high temperature coke-oven tar or fractions thereof, are characterized by, in their raw state, such a percentage of high molecular complexes or polymerized products that the solvents of the present invention, that is to say, solvents of increased boiling range'and solvency, are not possible of manufacture therefromv directly, but the starting material must first be subjected to the controls of the present process wherein, hydrogen flow, among other things, depolymerizes said molecular complexes.

The depolymerized or partially depolymerized tar or fraction of tar, is then stripped of a percentage of its low boiling ends whereby to provide the intermediate parent material of the solvents of the present process, said intermediate material having increased boiling range and lowered solvency. The residue incidental to said stripping may, because of its .depolymerized or partially depolymerized condition serve as recycle material, with or without the addition of other Vstarting material to the end that conversion of the starting material may approach volume for volume of said starting material into solvents of the present invention.

In the conversion of the starting material, partially or approaching unity, into the solvents of the present process, temperatures of as low as 300 C. are usable; pressures as low as 50 atmospheres may be used. However, temperatures and pressures of an increased range provide better commercial practice of the present invention. The time element is desirably that period which aords commercial recoveries of the products of. and incidental to, the present invention.

Concerning gas flow, flows of hydrogen or hy-v drogen containing gas are usually held in excess of 2.000 cubic feet per barrel material treated. In the step-wise application of hydrogen whereby to provide the solvents of the present invention, a few trials when using any of the starting materials will determine the gas flow, when coordinated with the selected temperature and pres, sure conditions to effect aforesaid depolymerizing conditions. 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 ow that provides depolymerizing conditions to the end that solvency. specic gravity, viscosity and boiling'range are lowered.

Concerning the gas flow that increases boiling intermediate starting materials under chosen coordination of temperature and pressure will readily determine the desirable gas flow. For a given coordination of temperature and pressure, the gas flow in the last instance is lower 4than the gas flow in the rst instance..

Using some starting materials, a gas flow of from 10,000 to 15,000 cubic feet per barrel, or

higher, has proven satisfactory for aforesaid depolymerizing conditions, and gas flows in the order of 46,000 to 8,000 cubic feet, or lower when increasing solvency and boiling range has proved satisfactory.

By the term benefciated 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 one or more steps of the present invention.

After the starting tar or fraction thereof has been subjected to depolymerizing action as aforestated, the stripping step may be effected at any point selected within a wide range to provide a cut which after further processing is capable of providing substitutes for benzol and/or toluol and/or Xylol and/or naphthas, and plasticizers.

Thus the depolymerized starting material may be cut to secure a low boiling product according to the need at hand, said low boiling cut then being subjected to the action of hydrogen that increases solvency and boiling range. The residue from said cut being recycled, if desired, to the end that substantially total conversion be eiected.

All catalysts effective in the presence of hydrogen for aforementioned purposes are usable.v

As for instance, chromiummolybdenum, vanadium, uranium, cobalt, copper and their compounds, for instance suliides and/or oxides; promoted or not; with Vor without small amounts of alkali, acid or halide, or derivatives thereof; small amounts of halogen or halogens, assuch, or incorporated with lother substances; effective catalysts deposited on carriers, as for instance gels, earths, carbon, or the like; in various shapes, as for instance forms, extruded shapes or lengths, pellets, comminuted; mixed with other material possessing desired action or not; with or without'other material effecting splitting or not.

When using catalysts, it may be desirable at times to use a comminuted catalyst during the period of the process characterized by depolymerization; thereafter, and during the period characterized by increase in solvency and boiling points, to use a rigid catalyst.

By the terms 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 aforenamed materials to the process of the present invention, it may be desirable prior to the depolymerizing step to at least partially depolymerize the molecular complexes by the use of a solvent. Said solvent may be added in small amounts, or up to volume for volume, or more, may be used. Refractory solvents are desirable, but others more susceptible to the reactions inherent in and to the present process are usable.

range and solvency, a few trials with any of the COIlCelIlIlg Solvents. it may be Said that '6313 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 depolymerizing action of hydrogen, as aforestated, may be effected in one or more cycles or chambers, with or without releasing the pressure and with or without variations of process controls, including changes in either temperature, pressure and/or gas flow; the final action of hydrogen according to the present invention may be effected in one or more cycles or chambers, with or without releasing pressure and with or Without variation of process controls, including changes in either temperature, pressure and/or gas flow.

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 action of hydrogen that increases solvency and boiling point. 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 a single high pressure chamber, a series thereof, a parallelism thereof, including a multiplicity thereof.

The solvent of the present invention may, as aforestated, be fractionated to provide solvents of various boiling ranges, and in the instance where said solvents are processed from a deep cut on the depolymerized material, the highest boiling fractions thereof serve as especially eicacious products in the coating industry or the like, however, no further mention is herein made of same.

The term coal tar as used herein means tar produced by the high temperature carbonization of coal, as for instance, high temperature coke oven tar and gas house tar.

Minor changes may be made without departing from the spirit of the present invention.

I claim:

1. In the production of solvents from a mixture of high temperature coal tar fractions, the process which comprises: subjecting said mixture of tar fractions to a first action of flowing hydrogen whilst contacting a cobalt compound as catalytic material, with time, temperature and pressure so controlled as to provide a beneciated material of lowered boiling range; stripping low boiling fractions from the beneciated material and subjecting at least a portion of said low boiling fractions to a second action of hydrogen wherein the flow is less than about 8,000 cubic feet per barrel material treated, with time, temperature and pressure so controlled as to increase boiling range and solvency.

2. The process of claim 1 in which the rst gas flow is in excess of about 10,000 cubic feet per barrel material treated and the second gas flow is selected between the limits of 2,000-8,000 cubic feet per barrel material treated.

JACQUELIN E. HARVEY, JR.

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