US3184401A

US3184401A - Process for producing hydrogenenriched hydrocarbonaceous products from coal

Info

Publication number: US3184401A
Application number: US167431A
Authority: US
Inventors: Gorin Everett
Original assignee: Consolidation Coal Co
Current assignee: Consolidation Coal Co
Priority date: 1962-01-19
Filing date: 1962-01-19
Publication date: 1965-05-18
Anticipated expiration: 1982-05-18

Description

United States Patent Ofiice 3,184,40l Patented May 18, 19.65

3,184,401 PROCESS FOR PRODUCING DROGEN- ENRICHED HYDROCARBGNACEOUS PROFE- UCTS FROM COAL Everett Gorin, Pittsburgh, Pa, assignor to Consolidation Coal Company, Pittsburgh, Pa., a corporation of Pennsylvania No Drawing. Filed Jan. 19, 1962, Ser. No. 167,431 3 Claims. (Cl. 208--8) This invention relates to an improved process for producing hydrogen-enriched hydrocarbonaceous products from coal. More particularly, this invention relates to a process for removing ash, i.e., metallic contaminants and the like, from ash-containing coal extract prior to catalytic hydrogenation thereof.

As described in my copending applications Serial No. 61,518, filed October 10, 1960, now US. Patent No. 3,018,242; and Serial No. 154,451, filed November 24, 1961, now US. Patent No. 3,143,489, valuable liquid products such as gasoline may be derived from coal by initially subjecting the coal to solvent extraction, whereby a mixture of coal extract and undissolved coal residue is'bbtained. After separating the extract from the residue, the extract is catalytically hydrogenated to yield a hydrogen-enriched hydrocarbonaceous liquid suitable for subsequent refining to gasoline, for example via a refining scheme such as described in my copending application Serial No. 154,451, supra.

The extract obtained by the solvent extraction of coal, after being separated from the undissolved coal residue, contains a minute, but economically prohibitive, amount of metallic contaminants, sometimes hereinafter referred to as ash. If this ash is not removed from the coal extract, the ash tends to deposit on the catalyst contained in the hydrogenation zone thereby causing a more rapid decrease in the activity of the catalyst than would otherwise be experienced. Such decrease in activity forces resort to more frequent replenishment of the catalyst with either regenerated or fresh catalyst.

While a few methods have been previously suggested for removing ash from coal extract (for example see US. Patent 2,141,615), these methods are economically prohibitive because they all involve deashing the coal extract at a relatively low temperature, generally below 100 C. Since the solvent extraction and catalytic hydrogenation zones are usually operated at a temperature of at least 250 C., and normally 350 to 450 C., the extract must thus be cooled from the relatively high extraction temperature to the relatively low deashing temperature; deashed; and then reheated to the hydrogenation tem perature. Obviously it is desirable that the extract be deashed with the minimum amount of, and preferably without any, cooling and reheating. Furthermore, deashing at low temperatures, i.e., below 100 C., requires the addition of hydrocarbonaceous solvent to the extract in excess of the amount used for solvent extraction in order to render the extract sufficiently fluid for the deashing treatment. The deashing cost is thus increased by the increased Volume of liquid that must be treated and by the cost associated with recovering and recycling the additional hydrocarbonaceous solvent. Unfortunately, a method for deashing ash-containing coal extract without the above disadvantages has heretofore not been developed.

Accordingly, it is an object of this invention to provide a novel and an economic process for producing hydrogenenriched hydrocarbonaceous products from coal via solvent extraction, deashing, and catalytic hydrogenation, which process is free from the aforementioned disadvantages.

It is another object of this invention to provide a novel process for deashing coal extract.

It is still another object of this invention to provide a novel and an economic process for deashing coal extract without having to excessively cool the extract prior to deashing, and reheat the deashed extract prior to hydrogenation.

In accordance with my invention, ash-containing extract obtained via the solvent extraction of coal is deashed in admixture with a hydrogen-transferring hydrocarbonaceous liquid at a temperature which is at least as high as the temperature at which hydrogen is transferred from the liquid. Normally hydrogen is not transferred from a hydrogen-transferring hydrocarbonaceous liquid below 250 C. The temperature at which hydrogen is transferred from the hydrogen-transferring hydrocarbonaceous liquid is hereinafter referred to as hydrogentransferring temperature. The resulting deashed extract is subsequently catalytically hydrogenated to yield the desired hydrogen-enriched hydrocarbonaceous product.

When ash-contm'ning extract is deashed without first substantially cooling the extract, for example, at a tem erature above 250 C., degradation of the extract occurs such that the resulting deashed extract is more difiicult to catalytically hydrogenate and gives poorer hydrogenation yields than extract which has not been deashed. The degradation is manifested by the formation of coke and by the increase in the high molecular weight, hydrogen deficient portion of the extract. The benzene insoluble content of the extract is a measure of this undesirable, high molecular weight extract portion. For example, when extract is deashed with acidic reagents at above 250 C., not only is coke formed, but the benzene insoluble content of the extract increases from about 38 weight percent in the feed extract to more than weight percent in the deashed extract. Surprisingly, however, when the same deashing treatment is conducted at even higher temperatures (above 300 C.), but in the presence of a hydrogen-transferring hydrocarbonaceous liquid, degradation of the extract is not only prevented, but sufficient hydrogen transfer occurs to actually reduce the benzene insoluble content of the treated extract.

Thus, by deashing ash-containing coal extract by the process of this invention the following occur:

(a) The economically undesirable cooling-reheating cycle is at least markedly minimized;

(b) The necessity for hydrocarbonaceous solvent in excess of the solvent used for solvent extraction is eliminated, as more fully explained hereinafter;

(c) The extract does not undergo harmful degradation during deashing;

(d) The resulting deashed extract is easier to hydrogenate and gives better hydrogenation yields than extract which has not been deashed; and

(e) Most importantly, hydrogenation catalyst life is markedly extended when deashed extract is used.

Hydrogen-transferring hydrocarbonuceous liquids Suitable hydrogen-transferring hydrocarbonaceous liquids are those predominantly polycyclic hydrocarbons which are partially or completely hydrogenated. Polycyclic hydrocarbon mixtures are generally employed, and are preferably derived from intermediate or final steps of the process of this invention. Normally the polycyclic hydrocarbons or mixtures thereof boil above 200 C. and preferably between 260 and 425 C.

Partially hydrogenated polycyclic hydrocarbons are the most active and preferred type of hydrogen-transfer liquids. Examples of such materials are the di, tetra, and octa hydro derivatives of anthracene and phenanthrene; etrahydronaphthalene; and alkyl substituted sponding partially hydrogenated compounds. If desired,

non-hydrogen-transferring liquids such as naphthalene, anthracene, biphenyl, and their alkyl substituted derivatives may be present in admixture with the hydrogentransferring materials, for example, such is the case when the hydrogen-transferring hydrocarbonaceous liquid is obtained from intermediate or final steps of the process of this invention. a

' While other materials may be admixed with the hydrogen-transferring hydrocarbonaceous liquid during deashing according to the process of this invention, it is important that sufiicient hydrogen-transferring liquid be present to prevent extract degradation. Normally, the ration of hydrogen-transferring hydrocarbonaceous liquid to extract which is used during deashing varies between about 0.5/1 and /1, and preferably between l/l and 2/1.

Specific deashing methods Any deashing process which is suitable for removing at least a portion of the ash contained in coal extract at a temperature above 250 C.'is applicable to the process of this invention. The essence of my invention is that the deashing must be accomplished in the presence of the hydrogen-transferring hydrocarbonaceous liquid when extract is deashed above 250 C.

Suitable specific deashing methods are, for example, washing the ash-containing extract with organic or inorganic acids such as described in US. Patent 2,141,615. Aqueous solutions of strong inorganic acids such as hydrochloric acid and phosphoric acid are particularly suitable. i i

For a better and more complete understanding of my invention, its objects and advantages, reference should be had to the following description.

Preferred embodiment I The following is a description of the. preferred embodiment of this invention. Briefly, the process of the preferred embodiment comprises:

Coal, preferably high volatile bituminous coal such. as Pittsburgh Seam coal, is subjected to solvent extraction under the following conditions.

Solvent extraction conditions Conditions Broad Preferred Temperature 800 to 500.C 375 to 420" 0. Pressure 1 to 6500 p.s.i.g-;" 1 to 600 p.s.i.g. Solvent to coal (wt. r 0.5/1 to 4/1- 1/1 to 2/1. Residence time 1 to 120 min 5 to 30 min.

Any solvent extraction process may be used in the process of this invention. Preferably, the extraction process is as described in my copending applications, supra.

Any of the well-known coal extraction solvents'may be used in the extraction zone. It is preferred, however, that the solvent be a hydrogen-transferring hydrocarbonaceous liquid such as previously described. Thus, the solvent can be introduced with the extract into a deashing zone without having to add additional hydrogen-transferring liquid. 7

The mixture of extract, solvent, and residue is conducted, without substantial cooling, to a conventional type separation zone wherein the residue is separated from the extract and solvent. Preferably, substantially all of the residue is recovered from the liquid extractsolvent mixture.' The separately recovered residue may be subsequently used as boiler fuel or subjected to a fluidized low temperature carbonization process such as described in my copending applications, supra.

Any conventional type separation 'zone may be used, for example,'filtration zone, settling zone, and the like.

The separated extract, with or without the extraction solvent, is conducted with minimal or no cooling into a deashing zone wherein at least a portion of the ash contained in the extract is removedtherefrom. The extract is deashed in the presence of a hydrogen-transferring hydrocarbonaceous liquid.

In no event is the extract cooled below 250 C: As to whether the extract is deashed at substantially the same temperature as extraction or slightly cooled before deashing depends on the. specific deashing treatment used. For example, when-extract is deashedwith a relatively dilute aqueous reagent, it is necessary to cool the extract below the critical point of water, i.e., 'below- 373 C., more fully described, and specifically claimed in the copending application of George P. Curran, Serial No. 437,626, filed February 19, 1965, and assigned to the assignee of the present application. However, if the extract is deashed with concentrated aqueous or nonaqueous reagents, the deashing maybe conducted at substantially the same temperature as the extraction temperature.

As previously mentioned, the extraction solvent itself may supply a portion or all of the hydrogen-transferring liquid. If desired, however, a portion or all of the solvent may be removed from the extract prior to deashing, for example, via distillation, and theextract deashed in admixture with fresh hydrogen-transferring hydrocarbonaceous liquid. Many methods of removing solvent and adding hydrocarbonaceous liquid will occur to those skilled in the art. The important step, however, is that the extract be deashed in the presence of a hydrogentransferring hydrocarbonaceous liquid.

, If desired, the extract may be deashed .without first separating the residue therefrom. Preferably, however, all of the residue and a-portion of the extraction solvent is separated from the extract (for recycle to the extraction zone) prior to deashing.

The deashed extract is introduced into a conventional type catalytic hydrogenation zone to yield hydrogenenriched hydrocarbonaceous liquids suitable for subsequent refining to gasoline and the like. Preferably, a portion of the hyrogen-transferring hydrocarbonaceous liquid is removed from the deashed extract prior to hydrogenation and conveyed directlly to the refining operations.

Because at least a portion and preferably all of the .ash has been removed from the extract, the hydrogenation catalyst life is markedly improved.

As previously mentioned, a portion of the hydrogenenriched hydrogenation products are recycled to extraction and deashing to provide the extraction solvent and hydrogen-transferring hydrocarbonaceous liquid, respectively.

The conditions generally employed during the catalytic hydrogenation of extract are a temperature in the range of 400 to 550 C.; a pressure in the range of 1000 to 10,000 p.s.i.g.; a hydrogen feed rate of from 5 to 100 standard cubic feet per pound, of extract; and a liquid feed rate of from 10 to 100 pounds per cubic foot of reaction volume. The catalytic hydrogenation zone may ,be any one of the conventional hydrogenation zones employed by-those skilled in the art such as a liquid phase or a vapor phase hydrogenation zone employing catalyst in the form of a fixed, gravitating, or fluidized bed therein. In addition, the catalyst may also be dispersed within the extract in the form of a slurry and thenintroduced into a slurry phase, catalytichydrogenation zone such that the catalyst is introduced into, maintained therein,

and withdrawn therefrom in the form of a slurry or a suspensoid. Suitable catalysts are, for example, metals of groups 5 to 8 of the Periodic Chart, preferably oxides r sulfides and combinations thereof. A preferred catalyst is one containing a metal oxide or sulfide of group 6 of the Periodic Chart, i.e., molybdenum combined with a relatively minor amount of a transition group metal oxide or sulfide such as cobalt or nickel. The active hydrocracking metals are preferably supported on a hydrous oxide support such as alumina gel.

The following is an example of the use of the process described in the preferred embodiment of this invention. Pittsburgh Seam coal is treated in a solvent extraction zone with a solvent recovered from a previous hydrogenation of extract under the following conditions:

Process conditions:

Temperature C 380 Pressure p.s.i.g 70 Solvent/coal ratio 1.0 Residence time hours 1.0

The solvent comprises a mixture of a 260 to 325 C. fraction and a 325 to 425 C. fraction in the ratio (by weight) of 1 to 1, respectively. The yields of the extraction treatment are:

Wt. percent original MAP 1 coal Extracts 57.8 Gases+H O 7.3 Residue 34.9

1 MAE means moisture-free and ash-free.

The extract is separated from the residue by filtration and the extract is then introduced into a topping still while the residue is carbonized in a fluidized low temperature carbonization retort.

The solvent boiling below 325 C. is removed in the topping still. The remaining solvent and extract are introduced into a deashing zone wherein the extract is contacted with aqueous hydrochloric acid (13.5 percent acid concentration in the aqueous phase) to remove ash therefrom. The extraction solvent that is not removed by topping supplies the desired hydrogen-transferring hydrocarbonaceous liquid.

The deashing conditions are as follows:

Process conditions:

Temperature C 315 Pressure p.s.i.g 1,600 Parts of aqueous phase per part extract 1.0

Process conditions:

Temperature 441 C.

Pressure 3,500 p.s.i.g.

Residence time (on fresh feed) 2.8 hours.

Catalyst COO-M003 on A1 0 base.

Wt. percent Yields: fresh feed 4 C -325 C. distillate 80.6

Because of deashing the extract prior to hydrogenation, 620 pounds of extract per pound of catalyst may be hydrogenated before the catalyst loses 10 percent of its activity as measured by hydrogen uptake. However, if the extract is not deashed and is hydrogenated under the same conditions, only pounds of extract per pound of catalyst can be hydrogenated before the catalyst is deactivated to the same extent.

Thus not only is the extract deashed without harming the extract via the process of this invention, but the deashing is accomplished without substantial cooling and reheating as was heretofore required.

According to the provisions of the patent statutes, I have explained the principles, preferred construction, and mode of operation of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. In a process for producing hydrogen-enriched hydrocarbonaceous products from coal wherein said coal is subjected to solvent extraction at a temperature between 300 and 500 C. to yield an ash-containing extract, at least a portion of which is subsequently catalytically hydrogenated to yield a hydrogen-enriched hydrocarbonaceous product, the improvement which comprises subjecting said extract, prior to any catalytic hydrogenation thereof, to treatment with an aqueous deashing reagent in admixture with a hydrogen-transferring hydrocarbonaceous liquid at a temperature above 250 C. but not above the temperature at which said coal was subjected to solvent extraction.

2. In a process for producing hydrogen-enriched hydrocarbonaceous products from coal wherein said coal is subjected to solvent extraction at a temperature between 300 and 500 C. to yield an ash-containing extract, at least a portion of which is subsequently catalytically hydrogenated to yield a hydrogen-enriched hydrocarbonaceous product, the improvement which comprises subjecting said extract, prior to any catalytic hydrogenation thereof, to treatment with a dilute aqueous deashing reagent in admixture with a hydrogen-transferring hydrocarbonaceous liquid at a temperature between 250 C. and 373 C.

3. In a process for producing hydrogen-enriched hydrocarbonaceous products form coal wherein said coal is subjected to solvent extraction at a temperature between 300 and 500 C. to yield an ash-containing extract, at least a portion of which is subsequently catalytically hydrogenated to yield a hydrogen-enriched hydrocarbonaceous product, the improvement which comprises subjecting said extract, prior to any catalytic hydrogenation thereof, to treatment with dilute aqueous hydro chloric acid in admixture with a hydrogen-transferring hydrocarbonaceous liquid at a temperature between 250 C. and 373 C.

References Cited by the Examiner UNITED STATES PATENTS 2,606,141 8/52 Meyer 208-214 3,018,241 1/62 Gorin 208--8 3,018,242 1/ 62 Gorin 2088 3,044,956 7/62 Burk et a1 208-252 ALPHONSO D. SULLIVAN, Primary Examiner.

Claims

1. IN A PROCESS FOR PRODUCING HYDROGEN-ENRICHED HYDROCARBONACEOUS PRODUCTS FROM COAL WHEREIN SAID COAL IS SUBJECTED TO SOLVENT EXTRACTION AT A TEMPERATURE BETWEEN 300 AND 500*C. TO YIELD AN ASH-CONTAINING EXTRACT, AT LEAST A PORTION OF WHICH IS SUBSEQUENTLY CATALYTICALLY HYDROGENATED TO YIELD A HYDROGEN-ENRICHED HYDROCARBONACEOUS PRODUCT, THE IMPROVEMENT WHICH COMPRISES SUBJECTING SAID EXTRACT, PRIOR TO ANY CATALYTIC HYDROGENATION THEREOF, TO TREATMENT WITH AN AQUEOUS DEASHING REAGENT IN ADMIXTURE WITH A HYDROGEN-TRANSFERRING HYDROCARBONACEOUS LIQUID AT A TEMPERATURE ABOVE 250* C. BUT NOT ABOVE THE TEMPERATURE AT WHICH SAID COAL WAS SUBJECTED TO SOLVENT EXTRACTION.