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United States Patent (19) 11 Patent Number: 5,414,189 Chen Et Al

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United States Patent (19) 11 Patent Number: 5,414,189 Chen Et Al . US005414189A United States Patent (19) 11 Patent Number: 5,414,189 Chen et al. 45 Date of Patent: May 9, 1995 54) ISOLATION OF HIGH PURITY (56) References Cited DAMONDOD FRACTIONS AND COMPONENTS U.SS. PATENT DDOCUMENTS M 3,944,626 3/1976 Honna et al. ....................... 585/812 75) Inventors: Catherine S. H. Chen, Berkeley Heights; Steven E. Wentzek, East OTHER PUBLICATIONS Brunswick, both of N.J. Aldrich Catalog (1991) by Aldrich Chemical Co. pp. 73) AssigneeAssignee: Mobilobul UalOil Corporation,Uorporation, Fairfax, Va.Va Vogel,1727. “Practical Organic Chemistry”, 3rd Ed (1956) 21 Appl. No.: 111,222 (Longman) pp. 108-122. 22 Filed: Aug. 23, 1993 Primary Examiner-Asok Pal Attorney, Agent, or Firm-Alexander J. McKillop; Related U.S. Application Data Dennis P. Santini; Robert B. Furr, Jr. (63) Continuation-in-part of Ser. No. 933,799, Aug. 24, 57 ABSTRACT 1992, abandoned. A process is disclosed for separating high purity dia 51 Int. Cl. ........................... C07C 7/04; CO7C 7/14 mondoid fractions from a mixture containing substi 52 U.S. C. .................................... 585/801; 585/812; tuted and unsubstituted diamondoid compounds. 585/815 58) Field of Search ........................ 585/812, 815, 801 4 Claims, 5 Drawing Sheets U.S. Patent May 9, 1995 Sheet 2 of 5 5,414,189 00'000€ +' SENWINWWW|02 00’000Z SONOOGS/HWII ENWINWWWQW-Bºld MOTSMETIO8 00'09 "?INH3 U.S. Patent May 9, 1995 Sheet 3 of 5 5,414,189 FIG. 3A 220.00 ADAMANTANES FRACTION 60.00 A. Gd 2. 2 N EC c 100.00 40.00 1000.00 2000.00 3000.00 TIME/SECONDS SOLATED ADAMAN ANE IN HEPANE 110.00 geA 80.00 Z N 2 5000 20.00 1000.00 2000.00 3000.00 TIME/SECONDS U.S. Patent May 9, 1995 Sheet 4 of 5 5,414,189 FIG. 4A DAMANTANES FRACTION 60.00 u2 £o 4000s NN so a 20.00 0.00 1000.00 2000.00 3000.00 TIME/SECONDS SOLATED DAMANTANE IN HEPANE 40.00 ge 30.00 N£ 5 2000 10.00 0.00 F 1000.00 2000.00 3000.00 TIME/SECONDS U.S. Patent May 9, 1995 Sheet 5 of 5 5,414,189 RAMANTANES - TETRAMANTANES 30.00 A. Gd J£ 2000-: d a. 10.00 0.00 1000.00 2000.00 3000.00 TIME/SECONDS SOAED TRMANANE IN HEPANE 20.00 9/2 Od 52. s 10.00 0.00 1000.00 2000.00 3000.00 TIME/SECONDS 5,414,189 1. 2 mercially useful. As mentioned above, conventional SOLATION OF HIGH PURITY DAMONDOD distillation of diamondoid-containing solvent mixtures FRACTIONS AND COMPONENTS is complicated by the fact that diamondoid compounds exhibit vapor pressures which are unusually high for CROSSREFERENCE TO RELATED 5 their molecular weights. APPLICATIONS U.S. Pat. No. 5,120,899 to Chen and Wentzek, which This application is a Continuation-in-Part of U.S. is incorporated by reference as if set forth at length application Ser. No. 07/933,799, filed Aug. 24, 1992, herein, teaches a method of recovering the total dia now abandoned. mondoid mixture without contamination using a high O boiling point solvent which is injected into the natural FIELD OF THE INVENTION gas wellbore. The present invention relates to a method for recov Thus it would be desirable to provide a method for ering high purity diamondoid fractions and components separating these recovered diamondoid mixtures into from a mixture containing substituted and unsubstituted high purity fractions and components. diamondoid compounds. 15 SUMMARY OF THE INVENTION BACKGROUND OF THE INVENTION This invention provides a method for separating high Many hydrocarbonaceous mineral streams contain purity diamondoid fractions and components from a some small proportion of diamondoid compounds. mixture of alkylated and non-alkylated diamondoid These high boiling, saturated, three-dimensional poly 20 compounds. The steps of this invention are both coun cyclic organics are illustrated by adamantane, diaman terintuitive and highly effective for separating high tane, triamantane and various side chain substituted purity, high melting, unsubstituted diamondoids such as homologues, particularly the methyl derivatives. These adamantane, diamantane, and triamantane from a com compounds have high melting points and high vapor plex mixture of substituted diamondoids. pressures for their molecular weights and have recently 25 been found to cause problems during production and In addition, removing higher melting fractions from refining of hydrocarbonaceous minerals, particularly the diamondoid mixture useful as a feedstock in this natural gas, by condensing out and solidifying, thereby invention naturally lowers the freeze point of the result clogging pipes and other pieces of equipment. For a ing mixture, rendering the mixture more desirable as a survey of the chemistry of diamondoid compounds, see 30 component in a fuel or lubricant. The term “freeze Fort, Jr., Raymond C., The Chemistry of Diamond point’ as used herein refers to the highest temperature Molecules, Marcel Dekker, 1976, as well as U.S. Pat. at which the liquid mixture precipitates solids from the Nos. 5,019,660 to Chapman and Whitehurst and mixture. Freeze point behavior has been studied exten 5,053,434 to Chapman. sively, particularly in the fields of jet and rocket engine In recent times, new sources of hydrocarbon minerals 35 fuels. In these applications, it is generally accepted that have been brought into production which, for some blending in a lower molecular weight solvent such as unknown reason, have substantially larger concentra hexanes or heptanes will effectively lower the freeze tions of diamondoid compounds. Some of these diamon point. Removing lower boiling fractions from the feed doid mixtures cause severe plugging problems in down stock useful in the present invention, on the other hand, stream processing equipment. Other diamondoid mix 40 surprisingly causes no substantial increase in the freeze tures remain in the liquid phase under natural gas pro point, also has been found to beneficially depress the cessing conditions and can be easily removed in a liquid freeze point. This behavior runs counter to the industry knockout drum. practice of blending lighter fractions with heavier frac The problem of diamondoid deposition and plugging tions to lower the freeze point of the resulting mixture. in natural gas production equipment has been success 45 Further, the lower boiling components are useful as fully addressed by a controlled solvent injection pro specialty chemicals and as feedstocks for pharmaceuti cess. U.S. Pat. No. 4,952,748 to Alexander and Knight cals. teaches the process for extracting diamondoid com The method of the invention comprises the steps of pounds from a hydrocarbon gas stream by contacting (a) providing a feed mixture of diamondoid com the diamondoid-laden hydrocarbon gas with a suitable SO pounds containing at least about 40 total weight percent solvent to preferentially dissolve the diamondoid com substituted and unsubstituted adamantane, at least about pounds into the solvent. U.S. Pat. No. 5,016,712 to 30 total weight percent substituted and unsubstituted Cullick and Roach teaches a method for locating the diamantane, and at least about 5 total weight percent solvent injection point within the natural gas wellbore. substituted and unsubstituted triamantane; Further studies have revealed that separating dia 55 (b) distilling an overhead fraction from said feed mix nondoid compounds into high purity fractions is com ture of diamondoid compounds, said overhead fraction plicated by their overlapping boiling points and rela characterized by an average carbon number which is tively high vapor pressures. U.S. Pat. Nos. 4,952,747, lower than the average carbon number of said feed 4,952,749, and 4,982,049 to Alexander et al. teach vari mixture, and having a freeze point which is higher than ous methods of concentrating diamondoid compounds 60 the freeze point of said feed mixture; which dissolved in a solvent for, among other reasons, (c) cooling said overhead fraction to a temperature recycling the lean solvent fraction for reuse, and each of above the freeze point of said feed mixture; and these processes produces an enriched solvent stream (d) recovering unsubstituted diamondoid solids from containing a mixture of diamondoid compounds. While said overhead fraction at a purity of at least about 90 these techniques meet the industrial need for a constant 65 weight percent. supply of relatively lean solvent for continuous recycle, In a preferred embodiment, the method further com the diamondoid-enriched streams rejected by these pro prises recrystallizing the unsubstituted diamondoid cesses are not sufficiently pure to themselves be com solids obtained in the recovery step (d) in a suitable 5,414,189 3 4 solvent such as hexanes or heptanes to a purity of at though this is not required. If the feedstock contains least about 99 weight percent. more than about 25 weight percent of diamondoid com The invention provides, in a second aspect, a method pounds which are normally solid under ambient condi for separating high purity diamondoid fractions from a tions, the method of the invention preferably comprises mixture of diamondoid compounds comprising the steps an additional short-path distillation step in the absence of: of reflux, or filtration at ambient temperature to remove (a) providing a feed mixture of diamondoid com solids. For a general description of short-path distilla pounds containing unsubstituted adamantane, unsubsti tion, see U.S. Pat. No. 5,120,899 to Chen and Wentzek, tuted diamantane, unsubstituted triamantane, and substi which is incorporated by reference as if set forth at tuted diamondoid compounds; O length herein. If the feedstock contains less than about (b) distilling a first overhead fraction from said feed 25 weight percent of diamondoid compounds which are mixture, said first overhead fraction characterized by an normally solid under ambient conditions, then the average carbon number which is lower than the average method may be carried out in a multistage distillation carbon number of said feed mixture, wherein said first apparatus without the optional short-path distillation or overhead fraction is further characterized by a higher 15 filtration steps.
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