Process for obtaining wax fractions from a feed wax

Abstract

A process for obtaining a wax fraction from a feed wax, the process comprising: (a) providing a molten feed wax in a container; (b) solidifying the feed wax by cooling; (c) increasing the temperature of the feed wax to a temperature at which a first fraction of the feed wax melts, said first fraction having a congealing point which is lower than the congealing point of the feed wax; (d) recovering the first fraction of the feed wax; (e) increasing the temperature of the remaining feed wax to a temperature at which a further fraction of the feed wax melts; and (f) recovering the further fraction of the feed wax. The feed wax comprises at least 75 wt.-% of linear alkanes and each recovered fraction comprises at least 19 wt.-% of the feed wax.

Claims

1. A process for obtaining wax fractions from an initial feed wax, the process comprising: (a) providing a molten feed wax in a container; (b) solidifying the feed wax by cooling; (c) increasing the temperature of the feed wax to a temperature at which a first fraction of the feed wax melts; (d) recovering the first fraction of the feed wax, said first fraction having a congealing point which is lower than the congealing point of the feed wax; (e) increasing the temperature of the remaining feed wax to a temperature at which a further fraction of the feed wax melts; and (f) recovering the further fraction of the feed wax; characterized in that the feed wax comprises at least 75 wt.-% of linear alkanes and the feed wax has an oil-content of less than 0.5 wt.-%, that the first fraction recovered in step (d) comprises 19 to 81 wt.-% of the feed wax, and wherein step (e) the temperature is increased to a temperature which is below a final melting temperature of the remaining feed wax and wherein steps (e) and (f) are repeated 1 to 3 times and wherein in the final repetition of step (e) the remaining feed wax is melted completely.

2. The process of claim 1, wherein the feed wax is separated into 2 fractions, each fraction comprising from 20 to 80 wt.-% of the initial feed wax, provided that the sum of the fractions is 100 wt.-%.

3. The process of claim 1, wherein the feed wax is separated into 5 fractions, each fraction comprising 19 to 24 wt.-% of the initial feed wax, provided that the sum of the fractions is 100 wt.-%.

4. The process of claim 1, wherein the feed wax is separated into 4 fractions, each fraction comprising from 20 to 40 wt.-% of the initial the feed wax, provided that the sum of the fractions is 100 wt.-%.

5. The process of claim 1, wherein the feed wax is separated into 3 fractions, each fraction comprising from 20 to 60 wt.-% of the initial feed wax, provided that the sum of the fractions is 100 wt.-%.

6. The process of claim 1, wherein the feed wax comprises >60 wt.-% of n-alkanes with chain lengths between 15 and 65 carbon atoms and a molar mass of 200 to 900 g/mol.

7. The process of claim 1, wherein the feed wax has a congealing point between 40 and 80 C.

8. The process of claim 1, wherein the feed wax is a wax produced by a Fischer-Tropsch-process.

9. The process of claim 1, wherein in steps (c) and (e) the temperature of the wax is increased at a rate of from 0.5 to 3 C. per hour.

10. The process of claim 1, wherein starting at step (c) the temperature is continuously increased throughout the process until the final recovering step (f).

11. The process of claim 1, wherein the fractional crystallization is conducted in a crystallizer comprising a steel box with a number of vertical cooling/heating plates.

12. The process of claim 1, wherein the congealing point of all obtained wax fractions is between 45 to 80 C. and the oil content is below 10 wt.-%.

13. The process of claim 1, wherein the flash point of the final fraction is at least 3 C. higher than the flash point of the initial feed wax, and the flash point of the first fraction is at least 3 C. lower than the flash point of the initial feed wax.

14. The process of claim 1, wherein the viscosity at 100 C. of the first fraction is not more than 0.3 mm.sup.2/s lower than the viscosity at 100 C. of the initial feed wax, and the viscosity at 100 C. of the final fraction is not more than 0.3 mm.sup.2/s higher than the viscosity at 100 C. of the initial feed wax.

15. The process of claim 1, wherein the needle penetration at 25 C. of the first fraction is not more than 6.0 1/10 mm higher than the penetration at 25 C. of the initial feed wax composition, and the penetration at 25 C. of the final fraction is not more than 16.0 1/10 mm lower than the penetration at 25 C. of the initial feed wax; and/or wherein the needle penetration at 40 C. of the first fraction is not more than 100.0 1/10 mm higher than the penetration at 40 C. of the initial feed wax, and the penetration at 40 C. of the final fraction is not more than 65.0 1/10 mm lower than the penetration at 25 C. of the initial feed wax.

16. A wax obtained by the process of claim 1.

17. The process of claim 2, wherein each fraction comprises 40 to 60 wt.-% of the initial feed wax.

18. The process of claim 17, wherein each fraction comprises about 50 wt.-% of the initial feed wax.

19. The process of claim 1, wherein the feed wax is separated into at least two different refined paraffin wax fractions.

20. The process of claim 19, wherein the final fraction has a flash point at least 3 C. higher than the initial feed wax flash point, and the first fraction flash point is at least 3 C. lower than the flash point of the initial feed wax.

21. The process of claim 19, wherein viscosity at 100 C. of the first fraction is not more than 0.3 mm.sup.2/s lower than viscosity at 100 C. of the initial feed wax, and viscosity at 100 C. of the final fraction is not more than 0.3 mm.sup.2/s higher than the viscosity at 100 C. of the initial feed wax.

22. The process of claim 19, wherein needle penetration at 25 C. of the first fraction is not more than 6.0 1/10 mm higher than needle penetration at 25 C. of the initial feed wax composition, and needle penetration at 25 C. of the final fraction is not more than 16.0 1/10 mm lower than needle penetration at 25 C. of the initial feed wax; and/or wherein needle penetration at 40 C. of the first fraction is not more than 100.0 1/10 mm higher than needle penetration at 40 C. of the initial feed wax, and needle penetration at 40 C. of the final fraction is not more than 65.0 1/10 mm lower than needle penetration at 25 C. of the initial feed wax.

23. The process of claim 19, wherein congealing point of the first fraction and congealing point of the final fraction differ at least 2 C. from the initial feed wax congealing point.

24. The process of claim 23, wherein the congealing point of the first fraction is at least 2 C. lower than the congealing point of the initial feed wax and the congealing point of the final fraction is at least 2 C. higher than the congealing point of the initial feed wax.

25. The process of claim 19, wherein the first fraction has a lower concentration of n-alkanes than the feed wax and the last fraction has a higher concentration of n-alkanes than the feed wax.

26. The process of claim 19, wherein at least two different refined paraffin wax fractions have congealing points, determined according to DIN ISO 2207, of between 54 to 68 C. and wherein at least one refined paraffin wax fraction has a congealing point of between 56 to 64 C.

27. The process of claim 19, wherein at least two different refined paraffin wax fractions meet the industry standard specifications for Fully Refined Paraffin 56-58, Fully Refined Paraffin 58-60, Fully Refined Paraffin 60-62, and/or Fully Refined Paraffin 62-64.

Description

EXAMPLES

Example 1

Separating Feed Waxes into Three Fractions

(1) Two feed waxes, a hydrotreated Fischer Tropsch derived wax (Sasolwax M5, hydrotreated and deoiled) and a fully refined crude petroleum-derived paraffin wax with a congealing point of 58-60 C. (Sasolwax 5803), both with an n-alkanes content of above 75 wt.-% and an oil-content according to DIN ISO 2908 of below 1 wt.-% were fractionated by crystallization into three different wax fractions with 33 wt.-%. The characteristics of the feed waxes are summarized in Table 2.

(2) TABLE-US-00002 TABLE 2 Properties of feed waxes Feed wax 1 (hydrotreated + Feed wax 2 deoiled FT-wax) (FRP 58-60) Parameters Unit Sasolwax M5 Sasolwax 5803 Congealing point C. 59.0 59.0 DIN ISO 2207 Oil content w/w % 0.43 0.45 DIN ISO 2908 PenN.sup.1) 25 C. 0.1 mm 12 15 DIN 51579 PenN.sup.1) 40 C. 0.1 mm 48 57 DIN 51579 Density 70 C. kg/m.sup.3 756.3 776.1 DIN EN ISO 12185 Viscosity 100 C. mm.sup.2/s 3.9 4.3 ASTM D7042 Flash point (COC) C. 235 247 ASTM D92 Sulphur content ppm 4.1 11.0 Saybolt Color 8 30 ASTM D156 n-alkanes content.sup.2) % 96.1 78.3 i-alkanes content.sup.2) % 3.9 21.7 .sup.1)needle penetration .sup.2)determined by gas chromatography according to EWF Method 001/03

(3) Fractional crystallization was conducted in a 6 liter laboratory crystallizer comprising an insulated double jacket steel pipe which was provided with steel rings in its inside. The crystallizer was separately charged with of 5 kg of each feed wax. The temperature was adjusted according to the profile shown in Table 3; temperature was controlled by a thermostat filled with water. Fractions were collected with an automatic sampling system.

(4) TABLE-US-00003 TABLE 3 Temperature profile of fractional crystallization Time Time Temperature [min] [min] [ C.] Filling 10 10 70 Cooling 240 250 49 Holding 60 310 49 Melting 483 796 70

(5) Feed wax 1 (hydrotreated and deoiled FT-wax) was separated into three 33.3% fractions. The properties of these fractions are shown in Table 4. The first fraction had an oil-content of 1.19% and a congealing point (CP) of 55.5 C. It meets the industry standard of a semi-refined paraffin wax (SRP 54-56; see Table 1). The second fraction had an oil-content of 0.4% and a congealing point of 57.5 C., and the third fraction had an oil-content of 0.18% and a congealing point of 63.0 C. These fractions meet the industry standard of fully refined paraffin waxes of grade FRP 58-60 and FRP 62-64, respectively (see Table 1).

(6) TABLE-US-00004 TABLE 4 Properties of fractions obtained from Feed wax 1 Oil- n- CP cont. PenN 25 PenN 40 alkanes Viscosity FP Corresponds Fraction % [ C.] [%] [0.1 mm] [0.1 mm] [%] [mm.sup.2/s] [ C.] to Feed 100 59.0 0.43 12 48 96.0 3.9 235 FRP 58-60 wax 1 1 33.3 55.5 1.19 18 146 95.7 3.6 219 SRP 54-56 2 33.3 57.5 0.40 12 72 96.2 3.9 227 FRP 58-60 3 33.3 63.0 0.18 9 25 96.8 4.6 251 FRP 62-64

(7) Table 4 shows that Fraction 3 has a much higher flash point (FP) than the feed wax. This is an additional advantageous because the flash point is an important parameter for high-temperature applications because fire hazard is reduced.

(8) Feed wax 2 (FRP 58-60) was also separated into three 33.3% fractions. The compositions of these fractions are shown in Table 5. The first fraction had an oil-content of 0.78% and a congealing point (CP) of 56.5 C. It meets the industry standard of a semirefined paraffin wax (SRP 54-56; see Table 1). The second fraction had an oil-content of 0.18% and a congealing point of 58.5 C., and the third fraction had an oil-content of <0.1% and a congealing point of 62.0 C. These fractions meet the industry standard of fully refined paraffin waxes of grade FRP 58-60 and FRP 62-64, respectively (see Table 1).

(9) TABLE-US-00005 TABLE 5 Properties of fractions obtained from Feed wax 2 Oil- N- CP cont. PenN 25 PenN 40 alkanes Viscosity FP Corresponds Fraction % [ C.] [%] [0.1 mm] [0.1 mm] [%] [mm.sup.2/s] [ C.] to Feed 100 59.0 0.45 15 57 78.3 4.3 247 FRP 58-60 wax 2 1 33.3 56.5 0.78 20 152 72.8 4.2 245 SRP 56-58 2 33.3 58.5 0.18 14 62 78.3 4.4 248 FRP 58-60 3 33.3 62.0 <0.1 11 29 83.9 4.5 250 FRP 62-64

Example 2

Separating Feed Waxes into Two Fractions

(10) In analogy to Example 1 feed waxes 1 and 2 were separated into two 50 wt.-% fractions. The composition of the fractions is shown in the following tables 6 and 7. Feed wax 1 gave a first fraction which meets the industry standard of a semi-refined paraffin wax (SRP 54-56) and a second fraction which meets the standard of a fully refined paraffin wax (FRP 60-62). Feed wax 2 gave two fractions which both correspond to the industry standard of fully refined paraffin wax (FRP 56-58 and FRP 60-62).

(11) TABLE-US-00006 TABLE 6 Separation of Feed 1 into two fractions by fractional crystallization Oil- n- CP cont. PenN 25 PenN 40 alkanes Viscosity FP Corresponds Fraction % [ C.] [%] [0.1 mm] [0.1 mm] [%] [mm.sup.2/s] [ C.] to Feed 1 100 59.0 0.43 12 48 96.0 3.9 235 FRP 58-60 1 50 56.0 0.98 16 127 95.8 3.6 222 SRP 54-56 2 50 61.5 0.29 11 51 96.6 4.2 242 FRP 60-62

(12) TABLE-US-00007 TABLE 7 Separation of Feed 2 into two fractions by fractional crystallization Oil- n- CP cont. PenN 25 PenN 40 alkanes Viscosity FP Corresponds Fraction % [ C.] [%] [0.1 mm] [0.1 mm] [%] [mm.sup.2/s] [ C.] to Feed 2 100 59.0 0.45 15 57 78.3 4.3 247 FRP 58-60 1 50 57.0 0.56 18 119 74.7 4.4 247 FRP 56-58 2 50 61.0 <0.1 11 31 82.5 4.6 250 FRP 60-62

Example 3

Fractionation of Unhydrotreated FT Wax

(13) Unhydrotreated Sasolwax M5 (Feed Wax 3) was subjected to the crystallization process of Example 2. Two fractions of 50 wt.-% were isolated. The first fraction had a congealing point of 49.5 C. and an oil-content of 6.7%. It meets the industry standard of a slack wax (Slackwax 45-55; Table 9). The second fraction had a congealing point of 65.0 C. and an oil-content of 0.9%, it meets the industry standard of a semi-refined paraffin wax (SRP 58-68; Table 9). This example shows that even feed waxes with comparatively high oil content can be fractionated by the crystallization process of the present invention.

(14) TABLE-US-00008 TABLE 8 Properties of fractions obtained from Feed wax 3 Oil- n- CP cont. PenN 25 PenN 40 alkanes Viscosity Corresponds Fraction % [ C.] [%] [0.1 mm] [0.1 mm] [%] [mm.sup.2/s] to Feed 100 57.5 3.4 27 98 80.5 3.4 Slackwax 56-64 wax 3 1 50 49.5 6.7 nd nd 64.1 3.1 Slackwax 45-55 2 50 65.0 0.9 11 33 85.8 4.2 SRP 58-68 nd: not determined