Method of marking hydrocarbon liquids

Abstract

The invention concerns a method of marking a hydrocarbon liquid comprising the ##STR00001##
step of adding to said liquid, as a tracer compound, a compound of Formula I or Formula II:
wherein at least one of R.sup.1-R.sup.6 in Formula I and at least one of R.sup.7-R.sup.14 in Formula II is selected from: i. a bromine or fluorine atom; ii. a partially or fully halogenated alkyl group; iii. a branched or cyclic C.sub.4-C.sub.20 alkyl group; iv. an aliphatic substituent linking two positions selected from R.sup.1-R.sup.6 in Formula I to one another or two positions selected from R.sup.7-R.sup.14 in Formula II to one another; or v. a phenyl group substituted with a halogen atom, an aliphatic group or halogenated aliphatic group
and none of R.sup.1-R.sup.6 in Formula I and none of R.sup.7-R.sup.14 in Formula II being a sulphonate group or COOR.sup.15, where R.sup.15 represents H, C.sub.1-C.sub.20 alkyl, C.sub.2-C.sub.20 alkenyl, C.sub.2-C.sub.20 alkynyl, C.sub.3-C.sub.15 cycloalkyl or aryl.

Claims

1. A method of identifying a hydrocarbon liquid, comprising: introducing a tracer compound of Formula I into a hydrocarbon liquid so as to form a marked hydrocarbon liquid, ##STR00004## wherein at least one of R.sup.1-R.sup.6 is selected from a branched, non-halogenated, C.sub.4-C.sub.20 alkyl group; and subsequently analysing a sample of a hydrocarbon liquid for the presence of said tracer compound to determine whether said sample is a sample of said marked hydrocarbon liquid, wherein at least 50% of the tracer compound is retained in the hydrocarbon liquid after a sample of the hydrocarbon liquid containing from 10 to 15 ppbv of the tracer compound has passed through a column of fresh activated charcoal.

2. The method of claim 1, wherein at least one of R.sup.1-R.sup.6 comprises an aliphatic alkyl substituent containing a quaternary-substituted carbon atom.

3. The method of claim 1, wherein the tracer compound has a boiling point within the distillation range of the hydrocarbon liquid or within 10 C. of the boiling point of the hydrocarbon liquid.

4. The method of claim 1, wherein more than one tracer compound is added to the hydrocarbon liquid.

5. The method of claim 1, wherein the tracer compound is added to the hydrocarbon liquid in such a quantity as to produce a final concentration in the liquid of less than or equal to 500 ppbv.

6. The method of claim 1, wherein at least one of R.sup.1-R.sup.6 comprises an aliphatic alkyl substituent containing a quaternary-substituted carbon atom.

7. The method of claim 1, wherein the tracer compound has a boiling point within the distillation range of the hydrocarbon liquid or within 10 C. of the boiling point of the hydrocarbon liquid.

8. The method of claim 1, wherein more than one tracer compound is added to the hydrocarbon liquid.

9. The method of claim 1, wherein the tracer compound is added to the hydrocarbon liquid in such a quantity as to produce a final concentration in the liquid of less than or equal to 500 ppbv.

10. A method of identifying a hydrocarbon liquid, comprising: introducing a tracer compound of Formula I into a hydrocarbon liquid so as to form a marked hydrocarbon liquid, ##STR00005## wherein at least one of R.sup.1-R.sup.6 is selected from a branched, non-halogenated, C.sub.4-C.sub.20 alkyl group, and subsequently analysing a sample of a hydrocarbon liquid for the presence of said tracer compound to determine whether said sample is a sample of said marked hydrocarbon liquid, wherein at least 50% of the tracer compound is retained in the hydrocarbon liquid after a sample of the hydrocarbon liquid containing from 10 to 15 ppbv of the tracer compound has passed through a column of fresh powdered sepiolitic clay.

Description

(1) The invention will be further described in the following examples. In the Examples, the test methods which are used are described below. The meaning of ppb v/v is parts per billion based on the volume of liquid tracer compound in the total volume of liquid. In the following tests, T1 is pentafluorobromobenzene; T2 is 3-(trifluoromethyl)bromobenzene.

(2) Test for Resistance to Removal by a Solid Adsorbant (Charcoal, Clay or Silica Gel)

(3) A 30 cm long chromatography column, having an inside diameter of 1 cm, was filled with the solid adsorbent to a depth of about 15 cm. The adsorbent was supported in the column on a glass frit. 15 ml of a diesel fuel containing 10 ppb v/v of the test tracer compound was added to the column and allowed to percolate through the adsorbent bed under gravity. The liquid eluting from the column was collected, sealed into an autosampler vial and analyzed immediately by gas chromatography-mass spectrometry (GCMS). The amount of tracer detected in the collected liquid is reported below in Table 1, as a percentage of the original concentration. Approximately 5 ml of liquid was retained on the column, presumably in the pores and voidage of the adsorbent particle bed.

(4) The adsorbents used were:

(5) Charcoal:a powdered activated Norit charcoal (type RBAA-3) from Fluka (product number 29238),

(6) Sepiolitic clay: a pure fine sepiolite clay from RS Minerals

(7) Silica gel 60 from Fluka (product number 60738)

(8) Fine powdered Al.sub.2O.sub.3 from Sigma Aldrich (product number 11028)

(9) Aluminium hydroxide, fine powder from Sigma Aldrich (product number 23918-6)

(10) Kaolin: fine powder from Sigma Aldrich (product number K7375)

(11) TABLE-US-00001 TABLE 1 Adsorbent Tracer Sepiolitic compound clay Charcoal Silica gel Al.sub.2O.sub.3 Al(OH).sub.3 Kaolin T1 90 88 94 97 91 100 T2 99 87 92 95 93 98
Multi-Pass Adsorbant Test

(12) The above test procedure was carried out using 50 ml of diesel fuel marked with 10 ppb v/v of the tracer compound and the eluted liquid was collected in an open beaker before being passed through a second column packed with fresh adsorbent. The liquid from the second column was collected in an open beaker before being passed through a third column packed with fresh adsorbent. A sample of the liquid collected from each column was taken for analysis by GCMS and the concentration of the tracer in the eluted liquid is shown in Table 2 as a percentage of the original concentration. When the concentration is greater than 100%, it is believed that the diesel fuel was retained on the adsorbent in preference to the tracer so that the solution became more concentrated.

(13) TABLE-US-00002 TABLE 2 Tracer Sepiolitic clay Charcoal compound 1.sup.st pass 2.sup.nd pass 3.sup.rd pass 1.sup.st pass 2.sup.nd pass 3.sup.rd pass T1 93 73 53 78 68 41 T2 102 99 94 70 40 18
Test for Loss of Tracer Compound on Standing

(14) 1 ml of diesel fuel marked with 10 ppb v/v of the test tracer compound was placed in an open topped 2 ml autosampler vial, and repeatedly analyzed by GCMS over the course of one day after standing in normal laboratory conditions to determine the concentration of the tracer compound in the diesel. The samples were interspersed with sealed calibration standards to correct for any instrument drift over the period of analysis. The concentration of the tracer in the liquid is shown in Table 3 as a percentage of the original concentration. When the concentration is greater than 100%, it is believed that the diesel fuel evaporated more quickly than the tracer so that the solution became more concentrated.

(15) TABLE-US-00003 TABLE 3 T1 T2 Concentration of tracer after 24 hours (%) 97 95
Test for Stability to Ultra-Violet Radiation

(16) 20 mls of diesel fuel marked with 10 ppb v/v of the test tracer compound were placed in each of two headspace vials which were sealed with airtight crimp tops, one of which was exposed to 365 nm UV light, the other left shaded on the laboratory bench. After 24 hours, approximately 0.5 mls was removed from each vial for analysis and crimp caps replaced with new. This was repeated again after 52 hours. Table 4 shows the % of the original concentration of tracer found by GCMS in the treated sample at the time shown.

(17) TABLE-US-00004 TABLE 4 Tracer compound 0 hrs 24 hrs 52 hrs T1 100 94.6 87 T2 100 98 91.2
Test for Resistance to Removal by Chemical Treatment

(18) A quantity of the diesel fuel marked with 13 ppb v/v of the test tracer compound was shaken vigorously with an equal volume of a chemical agent selected from 10% HCl in deionised water, 10% H.sub.2SO.sub.4 in deionised water, 10% NaOH in deionised water and methanolic KOH (3M aqueous KOH diluted 1:10 in methanol). The mixture was allowed to settle, then shaken for a further minute before settling again. A sample of the diesel layer was analyzed by GCMS and the concentration of the tracer in the treated diesel liquid is shown in Table 5.

(19) TABLE-US-00005 TABLE 5 Tracer 10% 10% 10% compound HCl H.sub.2SO.sub.4 NaOH KOH/MeOH T1 78 87 86 85 T2 73 89 88 88