US2291298A - Production of solvents and wood preservatives - Google Patents

Description

y 1942- J. E. HARVEY, JR 2,291,298

PRODUCTION OF SOLVENTS AND WOOD PRESERVATIVES Filed Aug. 14, 1940 STHET/NG FEED 4ND HYDROGEN- H YDEOGENHT/ON CHAMBER STIEIPP/NG CHHMBEB less/nus LOW BOIL 528 AND HYDROGEN HYDROGEN/=1 TION C'HHMB E12 END PRODUCT FOB FRflCT/O/VflT/ON TO SOLVENTH/VD WOOD PIEESERVAT/VE.

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Patented July 28, 1942 UNITEB STATEE PATENT OFFICE PRODUCTION OF SOLVEN'IS AND WOOD PRESERVATIVES Application August 14, 1940, Serial No. 352,659

1 Claim.

The present invention relates to the joint production of solvents and wood preservatives from hydrocarbons.

An object of the present invention is the joint production of solvents and wood preservatives from tars of aromatic content and fractions thereof.

Another object of the present invention is the joint production of solvents and wood preservatives from tars of aromatic content and fractions thereof under conditions that induce no substantial percentage of fractions of low solvency or low toxicity, or, stated in another manner, under conditions so controlled as to induce no substantial percentage of liquid chain structures.

Another object of the invention is the joint production of solvents of superior solvency and wood preservatives of added toxicity under conditions that induce no substantial percentage of carbonaceous deposition.

Other objects of the invention will become apparent from the following disclosures.

The following examples will serve to illustrate modes of practicing the present invention.

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 of the step carried out in each chamber and the contents thereof are indicated by legend,

Example 1.-A coal tar creosote, specific gravity 1.08, coke residue of 2% and having substantially 35% residue above 355 C. is passed through a high pressure reaction vessel while simultaneously flowing hydrogen therewith, at a temperature of 410 C. and 200 atmospheres pressure. The flow of hydrogen is 12,000 cubic feet per barrel creosote and the contact time is 45 minutes. The beneficiated creosote flowing from the reactor is inspected and will be found to have a reduced coke residue, specific gravity and viscosity; no substantial percentage of liquid chain structures will be induced, nor will there be any appreciable deposition of carbonaceous increment noticeable in the reaction chamber. The beneficiated creosote is distilled to an upper limit of 370 C'. and the distillate subjected to the action of hydrogen at 200 atmospheres pressure and 450 C. for such a length of time as to induce solvent properties and toxic increment, said beneficiation being further characterized by a final increment of low boiling fractions in excess of fractional increment in the higher boiling range. The finally beneficiated material is distilled up to 200 C. to provide the distillate as a solvent of superior solvency and the remainder as a wood preservative of enhanced toxic properties.

By the term enhanced solvency or superior solvency is meant that the solvent or solvents so described are superior in solvency to solvents currently on the market; by the term added toxicity or enhanced toxicity is meant that the wood preservative so described has a toxicity in excess of its parent material.

The point of fractionation between the solvent and wood preservative is not inflexible inasmuch as commercial solvents currently on the market have varied end points'and wood preservatives of current usage have varied initial boiling points. Thus, inasmuch as the end point of the solvent of the present invention substantially corresponds to the initial boiling point of the wood preservative, it will be immediately obvious that the point of fractionation is not inflexible, but may be varied at will.

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

SoLvENTs Identification: End point, C.

Benzol Toluol I-Ii-fiash naphtha 200 Heavy naphtha Above 200 W001) PRESERVATIVES Specifications 1. A. VI. P. A.:

a. Up to 210 C.,'not more than 5% b. Up to 235 C., not more than 25% 2. A. W. P. A.:

a. Up to 210 0., not more than 1% Up to 235 C., not more than 10% 0. Up to 355C not less than 65% 3. A. VJ. P. A.:

11. Up to 235 C.,-not more than 1 2). Up to 300 0., not more than 16 0. Up to 355 (3., not less than 45% A. W. P. A.:

a. Up to 210 0., not more than 8% b. Up to 235 0., not more than 35% 5. A. W. P. A.:

a. Up to 210 0., not more than 10% b. Up to 235 C., not more than 40% 6. A. W. P. A.:

it. Up to 210 0., not more than 5% Up to 235 0., not more than 7. Prussian Ry:

a. Up to 150 0., not more than 3% 5. Up to 200 C., not more than 10% 0. Up to 235 0., not more than 8. N. P. V. & L. A. #220:

a. 5% at 162 C. b. 97% at 270 C. 9. S. P. S. S. 0.:

a. 5% at 137 C. b. 95% at 257 C. 10. N. S. S. O.

a. I. B. P., 150 C. b. 5% at 205 C. c. 95% at 292 C. 11. Carbolineum, 270 C., I. B. P.

The foregoing abbreviations are explained as follows: A. W. P. A., American Wood Preservers Association; N. S. S. 0., Neville Shingle stain Oil; S. P. S. S. 0., Southern Pine Shingle Stain Oil.

Among other things, the present process is adapted to provide treatment of tars of aromatic content, or fractions thereof, with hydrogen as heretofore described, whereby to provide a newly induced low boiling point which comprises if desired the initial boiling point of the solvent, and may be controllably held at any point, as for instance:

SoLVEN'rs Identification: Initial point, C.

Benzol 78 Toluol 100 Hi-fiash naphtha 150 High boiling crudes 175 Heavy naphtha 150 Plasticizers 160 and above or, solvents of special nature may be produced, as for instance having lower boiling points than above listed.

The intitial or low boiling point of the beneficiated material is determined by intensity of process controls. Controls of lesser intensity producing higher initial boiling points and controls of greater intensity producing lower initial boiling points.

Example 2.--A coal tar, specific gravity 1.1641 and the coke residue in excess of 5% is passed through a high pressure reaction chamber while simultaneously flowing hydrogen therewith at a temperature of 400 C. and pressure of 225 atmospheres. The flow of hydrogen is 12,000 cubic feet per barrel feed stock and the time of contact is substantially one hour. The beneficiated material is found upon inspection to have reduced coke residue, specific gravity and viscosity; further inspection will show that no substantial percentage of liquid chain structures have been induced and that the controls of the process have induced no substantial percentage of carbonaceous increment. The beneficiated material is distilled to an upper limit of 330 C. and the distillate subjected to the action of hydrogen while flowing through a reactor at 440 C. and 200 atmospheres pressure. The hydrogen flow is 6,000 cubic feet per barrel feed and the time element so controlled as to induce solvent and toxic properties; the beneficiated material is further characterized by final increment of low boiling fractions in excess of fractionalincrement in the higher boiling range. The overall beneficiated material may be used as such or distilled to recover the solvent as a distillate and the remainder as a wood preservative, or, the wood preservative and the solvent both may be recovered as distillates, with the residue therefrom being recycled or serving as an article of commerce, for instance as a hinder, or plasticizer, valuable by reason of its enhanced value.

The term coal tar in this country is understood to meanitar produced by high temperature carbonization of coal, as for example, high temperature coke oven tar and gas house tar.

Example 3.--A coal tar pitch, specific gravity 1.23 and boiling substantially 15% at 355 C. is subjected to the action of hydrogen at 385 C. and 200 atmospheres pressure for a period of one hour. An identical cycle of hydrogen action is repeated upon the once hydrogenated pitch. The beneficiated pitch is then distilled to an upper limit of 325 C. and subjected to the action of hydrogen at a temperature of 465 C. and 225 atmospheres and for such a length of time as to induce solvent and toxic properties; the beneficiated material is characterized by a final increment of low boiling fractions in excess of fractional increment in the higher boiling range. The beneficiated material is distilled to an upper limit of 200 C. to provide the distillate as the solvent of the present invention and the remainder thereof as the wood preservative of an enhanced toxic value.

The term pitch as used herein includes the higher boiling fractions of tars, in other words, tar from which low boiling ends have been stripped, such low boiling ends being suitable for use per se as creosote, other wood preservative, or solvent. For instance, the final residue resulting from evaporating tar to dryness and then stripping wood preservative from the distillate is a very suitable pitch for use as a starting material of the present process.

The point of stripping the first beneficiated material characterized by reduction of coke residue, specific gravity and viscosity, is dependent upon the end point of the wood preservative desired.

An especially attractive mode of practicing the invention is to provide the out between the solvent and wood preservative around 270 C. The wood preservative of the indicated initial boiling point may serve as a substitute for carbolineum wood preserving oils; and the higher boiling portion of the solvent fraction serving as a substitute for certain plasticizing oils.

The residues from any of the distillation steps may be recycled for conversion to the products of the present invention. It has been found that the step-wise action of hydrogen has the eifect of causing coke residue to substantially or totally disappear.

All catalysts effective in the presence of hydrogen are usuable; especially effective are those based on metals of the sixth and eighth periodic groups, as for instance sulfiides and/or oxides, separately or in admixture; in any shape or form, as for instance comminuted, pellets, extruded lengths, supported on carriers as for instance on gels. or the like. Other materials essentially effective in the presence of hydrogen, as for instance splitting agents, may be added. Especially effective are the oxides and/or sulfides of chromium, vanadium, tungsten, cobalt, tin, molybdenum, or the like.

Hydrogen may be supplied as such, or in the form of hydrogen containing gas. Materials capable of supplying or generating hydrogen may be used.

Starting materials are tars of aromatic content or fractions thereof, said tars being derived from coal, wood, petroleum, gas and/or gases. Among such tars are included coke oven tar, gas house tar, low temperature tar, water gas tar, synthetic coal tar of petroleum derivation including gas and/or gases. Aromatic tars or fractions thereof at least once refined by hydrogen are especially effective starting materials.

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 from the starting material, high boiling fractions and pitches.

When using starting materials containing high molecular complexes, the molecular complexes may be depolymerized or reduced, including in size, in step-wise fashion until, if desired, sub-- stantially the entirety thereof which remains liquid appears in the solvents and wood preservatives of the present process.

By the term beneficiated 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.

As is well known, the action of hydrogen proceeds at lowered pressures, and the present process may be carried on at pressures as low as 50 atmospheres, however, pressures of in the order of 200 atmospheres and thereabove, as for instance 200-500 atmospheres, are preferred. The action of hydrogen in accordance with the present process proceeds at lowered temperatures, however, temperatures of in excess of 300 C. are preferred, the upper limit thereof being lower than that temperature which causes inordinate deposition of carbonaceous increment, as for instance coking.

The time element, because of the possible varied characteristics of the starting or intermediate starting materials, cannot be stated as an arbitrary period; in the first cycle of hydrogen action the time element is that period necessary for reduction of coke residue, specific gravity and viscosity and is generally in the order of one hour. However, using certain feed stocks, periods shorter than one hour have proven effective. Longer periods may be used. In the second cycle of hydrogen action, the period may be as short as one minute, at times more as for instance several minutes; broadly considered, the time element in the second cycle of hydrogen action is that period necessary for joint induction of solvent and toxic characteristics. Generally speaking, the time element in the second cycle is less than the time element of the first cycle.

The first action of hydrogen, when using certain starting feeds is characterized by a condensation of the boiling range toward the low ends.

Gas flows of in the order of 10,000-20,000 cubic feet per barrel feed stock in the first cycle of hydrogen action have proven satisfactory, however, higher or lower flows may be used; in the second cycle of hydrogen action gas flow of from 5,000-8,000 cubic feet per barrel feed stock has proven satisfactory, however higher or lower flows may be used.

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.

A convenient test for enhanced solvency is by evaluating the well-known Kauri-butanol number. Toxicity evaluations ma be made in accordance with the method described under the caption Method of conducting the tests, page 2, Technical Bulletin No. 346, March, 1933, U. S. Dept. of Agriculture.

Minor changes may be made in the steps of the process without departing from the spirit of the invention.

I claim:

In the joint production of solvents and wood preservatives, the process which comprises: subjecting a mixture of high temperature coal tar fractions to the action of a relatively high fiow of hydrogen with time, temperature and pressure so controlled as to reduce coke residue, specific gravity and viscosity; stripping the beneficiated material at a temperature not substantially in excess of 3'7 0 C. and subjecting at least a portion of the stripped low boiling materials in a stream to the action of a relatively low flow of hydrogen not in excess of about 6000 cubic feet per barrel material treated at a temperature in excess of 300 C., a pressure in excess of atmospheres and for such a length of time as to provide fractional increment of low boiling fractions in excess of fractional increment in the higher boiling range; and dividing the entirety of the treated material into a relatively low boiling solvent and a relatively high boiling oil of the wood preserving type, said oil last named boiling in accordance with specifications accepted in the trade for a tar derived wood preservative.

JACQUELIN E. HARVEY, JR.

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