US2321909A - Production of solvents and wood preservatives - Google Patents

Description

June 15, 1943. .1. E. HARVEY, JR 2,321,909

PRODUCTION OF SOLVENTS AND WOOD PRESERVATIVES Filed Aug. 14, 1940 Patented June 15, 1943 f- UNITED STATES PATENT OFFICE PRODUCTION OF lSOLVENTS AND WOOD PRESERVATIVES 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. 352,676

3 Claims. (Cl. ISG-53) matic content and fractions thereof.

Another object of the invention is the joint induction of solvent andvtoxic characteristics in tars of aromatic content and fractions thereof.

Still another object of the present invention is the controlling of reaction conditions so as to induce no substantial percentage of finally liquid chain structures that would preclude final production of a refined solvent having an aromaticity in the order of at least substantially 50%.

Yet another object of the present invention is the controlling of reaction conditions so as to induce no substantial percentage of finally liquid chain vstructures that would preclude the provision of the wood preservative of enhanced toxic value.

Another object of the present invention is the 'controlling of reaction conditions so that the process in continuous practice or discontinuous prac-k tice is not penalized due to coking action which would preclude commercial operation.

Another object of the present invention is the provision of a differential ow of gas and material under treatment whereby to remove newly induced low boiling fractions that tend to lower conversion rate on the high boiling fractions of the material under treatment.

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

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 ac. companying drawing wherein the figure is a diagrammatic sketch of an apparatus for carrying out a form of the process of the invention and wherein the nature ofthe step carried out in each chamber and the contents thereof are indicated by legend.

Errample 1.-A high residue creosote recovered from high temperature coke oven tar, said creosote being characterized by an initial boiling point 'of substantially 190 C. and a coke residue in ex'- cess of 1% is passed through a high pressure re# action chamber while simultaneously iiowing hydrogen therewith at a rate in excess of the ow rate o-f said creosote. The temperature is 400 C. and the pressure 200 atmospheres. Catalyst is molybdenum sulfide 'and the time of reaction sufficient to lower coke residue, specific gravity and viscosity. The gas movement is sufficient to strip newly induced low boiling fractions from the creosote under treatment. By the action of the gas movement the newly induced low boiling fractions are carried from the reaction zone for separation and recovery. The residual stripped material if desired while yet under a pressure of in excess 0f atmospheric is further subjected to the action of hydrogen whereby to induce a solvent Aincrement having an aromaticity of in the order of at least substantially 50%. The beneflciated material is stripped up to 200 C. with the stripped low ends serving as the solvent having an aromaticity of not substantially less than 50%. The residue incidental to said stripping operation is recycled or used as an article of commerce, as for instance, a binder or the like having lowered oxygen content.

Example 2.-A coal tar, specific gravity'substantially 1.1641 and having no preponderance of fractions boiling below C. is subjected to the action of hydrogen at 250 atmospheres pressure and 395 C. while flowing through a high pressure reaction vessel. Hydrogen is maintained in flow in excess of the ow of the tar under treatment so as to provide a stripping action on the newly induced low boiling tar fractions. The movement of gas carries the stripped low ends from the reaction zone for separation and recovery. The residual tar material while yet under pressure in excess of atmospheric is further subjected to the action of hydrogen at a pressure of susbtantially 300 atmospheres and 405 C. for a period of one hour; catalyst molybdenum sulfide. The beneciated tar residual material is stripped to an upper limit of 350 C. to provide the fraction boiling below 200 C. as a solvent having an aroniaticity of in the order of not substantially less than 50%, and the fraction boiling substantially 200-350 C. as a wood preservative of ladded toxic value. The residue may be recycled or used as an article of commerce.

Example 3.-A coal tar fraction having an initial boiling point of substantially 220 C. and in excess of 1% coke residue is passed through a high pressure reaction chamber while simultaneously flowing hydrogen therewith. The flow of hydrogen is in excess of the flow of said tar fraction, and the differential movement is so provided that the gas movement strips newly induced low boiling fractions from the tar fractions under treatment. The pressure is 300 atmospheres and the temperature 390 C.; time of contact 35 minutes and catalyst cobalt sulfide. The movement of gas carriesthe newly induced low boiling fractions away from the reaction zone. The residual stripped material if desired without total release of pressure is conducted to further treatment with hydrogen at a pressure of 300 atmospheres and a temperature of substantially 410 C. for a period of '7 5 minutes while contacting a vanadium sulfide catalyst whereby to reduce cokeresidue, specic gravity and viscosity. The beneciated material is stripped up to 205 C. with a low boiling material serving as the solvent having substantially 50% aromatic content and the residue serving as a wood preservative of added toxicity.

The present invention may be viewed broadly l or (2) a solvent as a distillate and a wood preservative as a residue or (3) a solvent as a distillate and a wood preservative as a distillate.

In the rst cycle of hydrogen action, the hydrogen is provided in flow that removes from the reaction zone at least a portion of the newly formed low boiling fractions whereby to redirect the action of hydrogen to the high boiling fractions under treatment. The first cycle of hydrogen action is characterized, among other things, by a reduction of coke residue, specic gravity and viscosity. The residual treated material if desired without total release of pressure is further treated with hydrogen at a temperature in excess of 300 C. and a pressure in excess of 50 atmospheres whereby to induce in the material under treatment, (1) solvent characteristics or (2) solvent and toxic characteristics.

After the induction of (1) solvent characteristics or (2) solvent and toxic characteristics, the material treated is then subjected to a stripping action, as for instance, by distillation, to recover the products having newly induced characteristics, as heretofore stated.

The ow of hydrogen may be used in excess of 10,000 cubic feet per barrel material under treatment, however, in some instances gas flows less than 10,000 cubic feet may be employed.

By the term beneficiated as used herein and in the appended claims is meant the starting or intermediate material at least once subjected to the action of hydrogen according to the present process.

Process variables, as for instance, temperature and pressure, are so coordinated with respect to other variables as to induce no substantial percentage of nally liquid chain structures that would preclude the production of solvents having an aromaticity of not substantially lower than 50% or that would preclude the production of wood preservatives having a toxicity in excess of the parent material, or a toxicity in excess of a fractional cut of comparable boiling range on the parent material.

When employing as starting materials a mixture of tar fractions having substantial residue above 355 C., the first cycle of hydrogen action may be described as depolymerizing or partially depolymerizing the high molecular complexes contained in the starting material, the while maintaining conditions that induce no substantial carbonaceous increment other than is inherent to the process as for instance, carbonaceous increment that causes closing down and turning around every three, four, or six months or longer.

Mixtures of tar fractions of aromatic content at least once refined by the action .of hydrogen serve as suitable starting materials.

Catalyst effective in the presence of hydrogen may be employed; as for instance, the oxides `and/or sulfides of the 6th and 8th periodic groups,

in admixture or separately; in any form or shape, as for instance, extruded in lengths, pellets, comminuted, or supported on carriers, as for instance, gels or the like. Oxides and/or suldes or molybdenum, tin, cobalt, vanadium, tungsten, uranium, manganese or the like are especially effective. Acid, acids, alkali, alkalis, halid, halids, halogen, halogens and/or derivatives thereof including substitution and addition products thereof, may also be employed for catalytic purposes incidental to the process. All catalysts effective in the presence of hydrogen for the indicated purpose may be used.

The first cyclel of hydrogen action is further characterized by a condensation of the boiling range toward the low ends.

The stripping action of hydrogen previously mentioned is so controlled that an inordinately high rate of gas flow does not cause excess coking conditions in the stripped material remaining in the reaction zone. A few trials with any of the starting materials will readily determine the desired flow when coordinated with other process variables. The gas flow in lesser amounts :s also maintained to preclude substantial coking conditions.

Under fixed conditions of temperature, pressure and feed characteristics the percentage of low boiling fractions stripped will vary as the gas flow. Under certain conditions stripped fractions -may include some boiling up to 300 C. 0r above.

By carrying on the process so that newly induced low boiling fractions, and others if desired, are removed, the material under treatment is placed in Aconditions so that subsequent actions of hydrogen may be directed to a greater extent to the higher boiling fractions on which it is desired to act preferentially.

After the final action of hydrogen, and in the event only a solvent is recovered from the benenciated material, said beneciated material may be further stripped to an upper limit to recover a substitute for any or all of the boiling ranges noted below:

Product: Boiling range Benzol 'Z8-120 C. Toluol 10Q-150 C. Hi-flash naphtha 15G-200 C. High boiling crudes 1'75-360'C. Heavy naphtha 15o-29rd#- Plasticizers 1GO-360 C.

Instead of controlling the process to provide a low boiling end of 78 C., as for instance, in the benzol shown, processing may be controlled to produce lower boiling products. The beneciated material may be distilled to 360 C., or above, with a distillate being fractionally cut according to the need at hand.

Other things being equal, intense process conditions producelower boiling points in the solvent, and the converse is true under certain conditions.

When recovering a solvent and a wood preservative from the finally beneciated material, the point of fractionation between the solvent and the wood preservative is not an inflexible point; inasmuch as the end point of the solvent of the present invention substantially corresponds to the initial boiling point of the wood preservative of the present invention, and inasmuch as commercial solvents have varying end boiling points and wood preservatives of commercial acceptance have varied initial boiling points, it is immediately obvious that the point of fractionation between the solvent and wood preservative is not inflexible, but may be varied at will.

In the tabular data shown below are solvents and wood preservatives of commercial acceptance, their end point and initial boiling point, respectively:

Solvents f Identification: End point Benzol 120 C. Toluol 150 C. Hi-ilash naphtha 200 C. Heavy naphtha Above 200 C.

Wood preservatives Identification: Initial point American Wood Preservers Association 5% at 210 C. American Wood Preservers Association 1% at 210 C. American Wood Preservers Association 11/2% at 210 C. American Wood Preservers Association at 210 C. Prussion Ry 3% at 150 C. Neville shingle stain oil 150 C. Southern Pine shingle stain oil 92 C. Carbolineum 270 C.

Starting materials of the present process comprise tars of aromatic content and fractions thereof, as for instance, those derived from wood, coal, petroleum or fractions thereof, gas and/or gases of carbon content.

As is well known in the art, the action of hydrogen proceeds at lowered temperatures and pressures, however, elevated temperatures and pressures provide for better commercial operation. Temperatures in excess of 250 C. are preferred and more especially temperatures in the order of or above 375 C., with the higher limit thereof being so controlled as to induce no substantial percentage of coking. Pressures of 50 atmospheres may be used, however, pressures in the order of 200-300 atmospheres are preferred. Pressures as high as practicable may be employed.

The time element in the rst cycle of hydrogen action includes that period necessary under the chosen temperature and pressure `conditions to strip, among other substances, at least a percentage of the newly induced low boiling fractions; with some starting materials, periods of in the order of 30 minutes will suice, however, longer or shorter periods may be used.

In the second cycle of hydrogen action, the time element is that period necessary to induce (l) solvency or (2) solvency and toxicity. With some of the intermediate vparent materials, periods of in the order of 30 minutes may be used, however, longer or shorter periods are usable.

It will be understood that, since an effect of hydrogenation is to lower boiling points, it may vbe expected that newly induced fractions will be vaporized as rapidly as their` boiling point is reduced below the temperature of the oven, the existing pressure being given consideration. The result therefore of continued actuation at a uniform temperature, with stripping of vapors by gas flow will be a removal of a material of a relatively narrow range of boiling points as compared to the starting material.

Therefore it becomes possible to conduct such operation by maintaining uniform temperature and pressure conditions, a feed of fresh starting material to maintain a uniform Volume and a gas flow for actuation and removal of the wanted product.

If the operating controls are such as to produce a high grade solvent, it will be all the more valuable because of its uniformity.

Minor changes may be made within the scope of the appended claims without departing from the spirit of the invention.

I claim:

1. In the production of solvents and wood preservatives, the process which comprises: subjecting a mixture of high temperature coal tar fractions to the action of hydrogen at a pressure of at least 250 atmospheres, a temperature at least in the order of 375 C. and for such a length of time as to reduce coke residue; so carrying on the process in a continuous manner as to provide a differential flow between the hydrogen and the mixture of tar fractions, said hydrogen flow being suicient to strip newly induced low boiling fractions from the material under treatment; subjecting the stripped residual material in entirety while yet under superatmospheric pressure to further hydrogen action at a temperature and pressure within the limits above named and for such a length of time as to provide newly formed oil which if distilled up to a temperature of about 205 C. will provide as a residual an oil of the wood preserving type boiling not more than about 10% at 210 C.; and dividing the treated residual to provide a relatively low boiling solvent and a relatively high boiling oil of the wood preserving type, said oil last named boiling not in excess of about 10% at 210 C.

2. The process of claim 1 wherein the temperature employed in said further hydrogen treatment is higher than when treating the overall starting material.

3. The process of claim 1 wherein the pressure employed in said further hydrogen treatment is higher than when treating the overall starting material.

J ACQUELIN E, HARVEY, J R.

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