Aug. 4, 1964 E. GoRlN 3,143,489 PROCESS FOR MAKING LIQUID FUELS FROM COAL Filed NOV. 24, 1961 Immun I.. 3,143,489 United States Patent C) ice Patented Aug. d, i‘àfîlâ 1 2 For example, in the Pott-Broche Process as close to 100 3,143,489 weight percent of the coal as possible is converted to coal PRÜCESS FÜR MAKING ‘LIQUID FUELS extract. It was believed the resulting coal extract would FROM CGAL Everett Gerin, Pittsburgh, Pa., assigner to Consolidation be more amenable to subsequent catalytic hydrogenation Coal Company, Pittsburgh, Pa., a corporation of 5 than the original coal. Unfortunately, when substantial Pennsylvania ly all of the coal is converted to extract, the resulting ex Filed Nov. 24, 1961, Ser. No. 154,451 tract is as diflicult to hydrogenate as the coal. More 9 Claims. (Cl. 208-8) over, the expense of extracting substantially all of the coal is economically prohibitive, as fully discussed in my This invention relates lto a process for making liquid copending application, Serial No. 61,518, filed October fuels from coal. More particularly, this invention relates l0, 1960, now Patent No. 3,018,242 which is assigned to to a process for making gasoline from coal at a cost the assignee of the kpresent application. which is equal to or less than the cost per gallon of simi I have found that liquid fuels such as gasoline can be lar gasoline made from petroleum (based on present economically obtained from coal if the coal is subjected coal and petroleum prices). to a “partial conversion process.” By this I mean a proc For many years investigators have been trying to de ess wherein the coal and the intermediate coal-derived velop commercially feasible processes for the production products are sequentially and incrementally upgraded in of hydrogen-enriched liquid fuels such as gasoline from a series of process steps, each of which is designed to par materials other than petroleum. Inasmuch as coal is the tially upgrade the particular feed material. It is surpris most abundant natural energy supply (on a B.t.u. basis) 20 ing, in view of the number of process steps that are used in the United States, much of the research eñort in this in my partial conversion process, that the gasoline pro country to find a synthetic liquid fuel has been devoted duced therefrom is less expensive than the gasoline pro to coal. Obviously, the importance of an economic proc duced via the aforementioned “complete conversion ess for producing gasoline from coal is immeasurable in processes,” i.e., the Bergius, Fischer-Tropsch, and Pott terms of the national welfare and defense. 25 Broche Processes. Coal is an ash-containing and hydrogen-deficient hy Accordingly, it is the primary object of this invention drocarbonaceous solid. By ash I mean metallic con to provide an economic process for the production of taminants and the compounds of silica that are present in synthetic liquid fuels from coal such that the resulting coal and coal-derived materials. In addition to contain fuels can be marketed on a competitive basis with simi ing ash, coal contains relatively large amounts of oxygen, 30 lar fuels produced from petroleum. sulfur, and nitrogen compounds which are undesirable in A further and more specific object of this invention is hydrogen-enriched liquid fuels such as gasoline. The to provide an economic, commercially feasible process for most serious disadvantage of coal, however, particularly the production of liquid fuels such as gasoline from coal with regard to the production of liquid fuels therefrom, by a series of sequential process steps, in each of which is the low hydrogen content of coal. For example, the 35 hydrogen is added or carbon is rejected, as the case may hydrogen to carbon ratio (weight ratio) of a representa be, under the most etiicient conditions for obtaining a tive Pittsburgh seam bituminous coal is about 0.06 to product which is most amenable to treatment in the suc 0.07, while the hydrogen to carbon ratio (weight ratio) ceeding process step. l of premium gasoline is about 0.14 to 0.18. It follows, In accordance with my invention, a process is provided therefore, that in any process for the production of liquid 40 for the conversion of coal to synthetic liquid fuels which fuels from coal, it is necessary to raise the hydrogen to comprises a series of sequential, partial conversion steps, carbon ratio of the coal either by the direct addition of each of which is designed to effect most efficiently the hydrogen or by the rejection of carbon or both. incremental addition of hydrogen or the progressive re Historically, only three processes to produce liquid jection of carbon, as the case may be. In its broadest fuels such as gasoline from coal have been tested com 45 embodiment the process comprises: mercially or semi-commercially to date. The oldest proc (l) Coal extraction; ess is the hydrogenation process, that is, the Bergius Proc (2) Separation of extract from undissolved coal ess. In the Bergius Process substantially all of the coal residue; is liquefied (via hydrogenation) in the presence of a (3) A primary catalytic hydrocracking zone; diluent hydrocarbon oil, hydrogen, and catalyst, under 50 (4) Catalytic hydroiining; and pressures up to 10,000 p.s.i.g. or higher. The eñiuent hy (5 ) A secondary catalytic hydrocracking zone. drogenation product is subsequently treated with addi In the foregoing listed steps, progressive, incremental tional hydrogen to yield liquid fuels. A second process is addition of hydrogen is effected in the following general the well-known Fischer-Tropsch Process wherein sub ized fashion. In the coal extraction step a small amount stantially all of the coal is gasiñed (via reaction with 55 of hydrogen is added to the extraction zone either by steam and oxygen). The raw synthesis gas is subsequent the use of a hydrogen-transfer solvent or by the intro ly catalytically treated to yield liquid fuels. The third duction of hydrogen gas or both. The purpose of this process is the Pott-Broche Process wherein substantially additional hydrogen is to permit the solvent extraction all of the coal is liquefied (via solvent extraction). ’I'he of up to 80 weight percent of the MAF (MAF means resulting coal extract is subsequently catalytically hydro 60 moisture-free and ash-free) coal. It is obviously desir genated to yield liquid fuels. In spite of extensive re able (for economic reasons) to recover a major portion search and development programs, however, none of the of the coal as coal extract. However, coal as such has above processes are economically attractive for the pro limited solubility in those solvents which it is practical duction of liquid fuels from coal in the United States to use in this process, unless hydrogen is added to partially today. 65 upgrade the coal. While larger addition of hydrogen will If any one reason can be attributed for the failure to permit greater depths of extraction, I have found that as develop a commercially feasible coal-to-gasoline process the depth of extraction exceeds 80 weight percent, the in the United States, it is the erroneous belief that sub hydrogen addition required to exceed such depths be stantially all of the coal substance should be immediate comes economically prohibitive, as further explained ly converted (via either gasiñcation or liquefaction) to an 70 ereinafter. intermediate product such as coal extract, raw synthesis The products of extraction are separated in the second gas, etc. which is then upgraded to the desired liquid fuel. step to yield extract and undissolved coal residue. Most 3,143,489 3 4 of the ash in the feed coal, that is, 99 weight percent or merely for convenience of reference and does not mean more, is recovered with the residue. The extract is a that the secondary hydrocracking Zone is subordinate to solid at room temperature and contains very little (in the primary hydrocracking ione. general, less than about 5 weight percent) . material boil For a better and more complete understanding of my ing below 400° C. The remainder of the extract is sub invention, its objects and advantages, reference should be stantially non-distillable without decomposition. had to the following description and to the accompanying Itis highly desirable that the extract be free of ash drawing which is a diagrammatic illustration of the pre~ before it or its upgraded products are introduced into ferred embodiment of the present invention. the hydrogenation zones, particularly the latter two hy PREFERRED EMBODIMENT drogenation zones. The presence of such ash constituents, 10 The following, with reference to the drawing, is a even in amounts as small as hundredths of one percent, seriously affects the activity and selectivity of the catalysts description of the preferred embodiment of the present in the three hydrogenation zones. Deashing can be ef invention. The preferred embodiment comprises: fected in the separation zone, in a distinctly separate ( 1) A solvent extraction zone 10 wherein the coal is deashing zone, in the primary hydrocracking zone, or in extracted; all three of these zones, as will be more fully discussed (2) A separation zone 20 wherein the extract is later. For the moment, it is sufficient to point out that separately recovered from the residue; the ash that is left in the coal extract following separation (3) A carbonization zone 26 wherein the residue is from the residue is quite different in composition from carbonized to produce a liquid distillate and a solid hydro that of the gross ash in the coal feedstock. carbonaceous solid product, referred to as “char”; The function of the primary catalytic hydrocracking (4) A deashing zone 40 wherein at least a portion of zone is to convert at least a portion of and preferably the residual ash remaining in the extract subsequent to the major portion of the non~distillable coal extract to separation from the residue is removed; an ash-free, distillable hydrocarbonaceous liquid boiling (5) Three primary catalytic hydrocracking Zones 50 below about 500° C.