US3687838A - Coal dissolution process - Google Patents

Abstract

PROCESS FOR DISSOLVING BITUMINOUS COAL BY HEATING A MIXTURE OF SAID COAL, A HYDROGEN DONOR OIL, CARBON MONOXIDE, WATER, AND AN ALKALI METAL OR AMMONIUM MOLYBDATE AT A TEMPERATURE OF ABOUT 400-450*C. AND UNDER A TOTAL PRESSURE OF AT LEAST ABOUT 4000 P.S.I.G.

Description

United States Patent @fice 3,687,838 Patented Aug. 29, 1972 3,687,838- COAL DISSOLUTION PROCESS Walter H. Seitzer, West Chester, Pa., assignor to Sun Oil Company, Philadelphia, Pa. No Drawing. Filed Sept. 14, 1970, Ser. No. 72,178 Int. Cl. Cg 1 06 US. Cl. 208-10 4 Claims ABSTRACT OF THE DISCLOSURE Process for dissolving bituminous coal by heating a mixture of said coal, a hydrogen donor oil, carbon monoxide, water, and an alkali metal or ammonium molybdate at a temperature of about 400-450 C. and under a total pressure of at least about 4000 p.s.i.g.

Much effort has been expended in attempting to convert coal into useful liquid fuels. A desirable approach is to liquefy the coal and subject it to the usual cracking and hydrocracking operations to provide fuel oils, gasoline, and the like. Much difficulty has been encountered, however, in the step of bringing the solid coal into liquid form so that it can be readily subjected to refinery operations and this has been particularly true with bituminous coals. Heretofore, available processes have yielded only limited solubility of bituminous coals and significant amounts of insolubles had to be removed by one means or another, all of which were expensive and decreased the efiiciency of the overall process.

It has now been found that bituminous coal may readily be essentially completely solubilized by an economical highly efiicient process. This is accomplished by subjecting a mixture of powdered coal, a donor solvent oil, carbon monoxide, water, and an alkali metal or ammonium molybdate to an elevated temperature of about 400-450 C. at a pressure of at least about 4000 p.s.i.g. {In this way the coal is essentially completely solubilized and the liquid which is obtained is readily handled and subjected to normal refinery operations to provide useful liquid fuels.

Coal useful in the process will be a bituminous coal and Illinois bituminous coal is particularly useful. However, other bituminous coals are also useful such as Rock Springs Wyoming coal, Utah coal, western Pennsylvania coal, and the like.

As indicated in the oil used in the process of the invention is a hydrogen donor solvent. These donor solvent materials are well known and comprise aromatic hydrocarbons which are partially hydrogenated, generally having one or more of the nuclei at least partially saturated. Several examples of such materials are tetralin, dihydronaphthalene, dihydroalkylnaphthalenes, dihydrophenanthrene, dihydroanthracene, dihydrochrysenes, tetrahydrochrysenes, tetrahydropyrenes, tetrahydrofluoranthenes and the like. Of particular value in the process of this invention as hydrogen donor solvents are the hydrophenanthrenes and hydroanthracenes such as dihydroanthracene. It will be understood that these materials may be obtained from any source, but are readily available from coal processing systems as anthracene oil, and the like. Of particular value are recycle oils from the coal dissolving process of the invention.

The molybdate salts which promote solution of the coal will preferably be an alkali metal (e.g. sodium, potassium, lithium, etc.) or an ammonium salt of molybdic acid; e.g., 6MO7024 4H20.

In carrying out the process of the invention, coal is powdered and mixed with the donor solvent, which is preferably anthracene oil, recycle oil, or its equivalent. Generally the ratio of coal to oil will be from about 1:4 to about 1:1 on a weight basis with a 1 to 1 ratio being preferred. Water and the molybdate are then added to the mixture and preferably this is added in the form of a solution of the molybdate in water. The amount of water present should be sufiicient to generate a water vapor pressure in the system of at least about one-fifth of the total pressure. Similarly, the amount of carbon monoxide will be suificient to generate at least one-fifth of the total pressure. It will be understood that the water pressure and carbon monoxide pressure account primarily for the total pressure in the system. The mixture of coal, oil, water and molybdate is then placed in a pressure vessel and pressured with carbon monoxide to the desired pressure and the contents of the pressure vessel heated to a temperature of about 400-450 C. Total pressure generated will be between about 4000 and about 6000 p.s.i.g. Dis solution of the coal occurs in a relatively short time, being on the order of about 0.5 to about 3 hours, and solution is essentially complete with very little if any insoluble material being present. Liquefied coal produced by the method of the invention is then subjected to normal cracking and hydrocracking reactions to obtain a liquid fuel such as gasoline, fuel oil, kerosene and the like.

The following examples will serve to further illustrate the invention:

EXAMPLE 1 A one-liter rocking autoclave is charged with g. of powdered bituminous coal (Illinois No. 6) and 75 g. of anthracene oil and then 75 g. of water containing 2.5 g. of ammonium molybdate. This represents 3.3% of the molybdate based on the coal charged. The reactor is sealed, pressure tested, and then pressured with carbon monoxide 'to 1200 p.s.i.g. The reactor is heated to 415 C. for one hour, allowed to cool, and the product then filtered to remove the solids which are washed with a toluene acetone mixture, dried, and weighed. The percent of organic solids undissolved is 10% whereas 33% is undissolved when the run is repeated without the molybdate.

'When the above example is repeated with sodium molybdate, essentially the same results are obtained.

It will be understood that numerous variations may be made from the above description and examples without departing from the scope of the invention.

The invention claimed is:

1. A process for dissolving bituminous coal which comprises heating at about 400 C. to about 450 C. under a total pressure of at least about 4000 p.s.i.g., a mixture of said finely divided coal, a hydrogen donor oil in an amount such that the weight ratio of coal to oil is from about 1:4 to about 1:1, carbon monoxide, water, and as a promoter an alkali metal or ammonium molybdate.

2. The process of claim 1 where the coal is an Illinois No. 6 coal, the oil is anthracene oil and the promoter is an alkali metal molybdate.

3 4 3. The process of claim 1 where the oil is a recycle oil 3,505,204 4/1970 Hoffman 208-10 and the promoter is sodium molybdate. 1,994,075 3/1935 Krauch et a1. 20810 4. The process of claim 1 where the oil is a recycle oil 2,002,997 5/1935 Herold et a1. 208-10 and the promoter is ammonium molybdate.

5 TOBIAS E. LEVOW, Primary Examiner References Cited P. F. SHAVER, Assistant Examiner UNITED STATES PATENTS 2,860,101 11/1958 Pelipetz 20810 2,191,156 2/1940 vPier et a1 20s 10 10 208-9 3,536,608 10/1970 Riedl et a1. 208-10