PROCESS FOR REMOVING CS2 FROM HYDROCARBON STREAMS

Abstract

A process for producing a hydrocarbon stream with reduced CS.sub.2 content, comprising contacting a hydrocarbon stream containing CS.sub.2 with a solid reactive CS.sub.2-scavenger which contains primary and/or secondary amino group-bearing hydrocarbon residues attached to a solid support, at a temperature in the range of from 0 to 300° C., and separating the obtained reaction product of and reactive CS.sub.2-scavenger from the hydrocarbon stream.

Claims

1-15. (canceled)

16. A process for producing a hydrocarbon stream with reduced CS.sub.2 content, comprising: contacting a hydrocarbon stream containing CS.sub.2 with a solid reactive CS.sub.2-scavenger which contains primary, secondary, or both amino group-bearing hydrocarbon residues attached to a solid inorganic support, at a temperature ranging from 0° C. to 300° C.; and separating the obtained reaction product of CS.sub.2 and reactive CS.sub.2-scavenger from the hydrocarbon stream, wherein the hydrocarbon stream is a naphtha containing stream and the primary, secondary, or both amino group-bearing hydrocarbon residues are aliphatic hydrocarbon residues bearing at least two amino groups.

17. The process according to claim 16, wherein the naphtha containing stream is a steam cracker feed stream or a stream coming from a steam cracker, or subsequent extraction, distillation unit, or both.

18. The process according to claim 16, wherein the solid reactive CS.sub.2-scavenger is in a form of a slurry, a fluidized bed, or fixed bed.

19. The process according to claim 16, wherein the solid inorganic support is chosen from silica, alumina, magnesia, titania, zirconia or mixed oxides thereof or zeolites, aluminosilicates, spinels, or carbon, and wherein the solid inorganic support is coated with organic layers.

20. The process according to claim 16, wherein the hydrocarbon residues each bear at least one primary amino group, at least one secondary amino group, or both.

21. The process according to claim 20, wherein the primary amino group, the secondary amine group or both in the hydrocarbon residue are separated from each other by a linear C.sub.2-C.sub.11-alkylene residue.

22. The process according to claim 20, wherein one primary amino group at the end of and at least one secondary amino group inserted in a linear C.sub.3-20-alkylene residue are attached to the solid support, or wherein at least one tertiary amino group and/or secondary amino group is inserted in a branched or cyclic C.sub.5-20-alkylene residue being attached to the solid support, or both.

23. The process according to claim 16, wherein the aliphatic hydrocarbon residues are coupled with the solid support through an alkoxysilyl group.

24. The process according to claim 16, wherein the solid reactive CS.sub.2-scavenger is formed by reacting a solid support, chosen from silica, alumina, magnesia, titania, zirconia or mixed oxides thereof or zeolites, aluminosilicates, and spinels or carbon with N-(trialkoxysilylalkyl)alkylenediamine, or wherein the solid reactive CS.sub.2-scavenger contains 0.1 mmol to 60 mmol primary and secondary amino groups/g, or both.

25. A solid reactive CS.sub.2-scavenger which contains primary and/or secondary amino group-bearing hydrocarbon residues attached to a solid inorganic support, wherein the solid reactive CS.sub.2-scavenger is formed by reacting a solid support, chosen from silica, alumina, magnesia, titania, zirconia or mixed oxides thereof or zeolites, aluminosilicates, and spinels or carbon with N-[3-(trialkoxysilyl)alkyl]alkylenediamine or N.sup.1-(3-(trialkoxysilyl)alkyldialkylenetriamine.

26. The scavenger according to claim 26, wherein the solid inorganic support is coated with organic layers.

Description

EXAMPLES

Example 1

[0070] The CS.sub.2-scavenger (structure 2 in FIG. 2) used in this example was made according to a modified literature procedure (J. Haz. Mat. 2007, 149, 650-656).

[0071] Silica gel (150.2 g; 0.2 to 0.5 mm silica gel (60 A) from Acros Organics) was mixed with 410 g demi-water in a 1 liter round bottom flask. Eight droplets of surfactant (Dreft from P&G Professional) were added. While swirling the flask, 46.3 gram (200 mmol) of N-(3-(Trimethoxysilyl)propyl)ethylenediamine was dropwisely added. After addition, the flask was connected to a rotary evaporator and heated to 92° C. for 2 hours while rotating the flask at 60 rpm (no vacuum). The flask was then cooled to room temperature, the water layer decanted and the product was washed 3 times with 200 ml demi-water. Finally, the product was filtered and dried in an oven overnight at 105° C.

[0072] Analysis: LOI(105): 1.0 wt %. CNS: 7.1 wt % carbon, 3.1 wt % nitrogen, <0.05 wt % sulfur.

[0073] The thus prepared CS.sub.2-scavenger was tested in a small scale fixed bed reactor. The CS.sub.2-scavenger particles (2.00 ml=1.13 g) were premixed with the same volume of inert material (SiC 0.5 mm granules) and loaded in the reactor (diameter=10 mm; L=50 mm). The bed was dried at 120° C. for 2 hours in an argon flow (4 ml/min) and finally cooled to the operation temperature (30° C. and 60° C.). A heptane feed containing 60 ppm CS.sub.2 (=50 ppm S) was passed over the bed at 0.2 ml/min (LHSV=6) and 3 barg pressure. Samples from the reactor were taken and analyzed for CS.sub.2 content by gas chromatography.

[0074] The CS.sub.2 adsorption from heptane is shown in FIG. 1. FIG. 1 shows the concentration of CS.sub.2 in heptane at the outlet of the reactor at 30° C. and 60° C. in time (LHSV=6 h.sup.−1, and 3 barg). The upper curve was measured at 30° C., the lower at 60° C. The data depicted in FIG. 1 show that the CS.sub.2 adsorbent performs surprisingly well. After 102 hours on stream, the CS.sub.2-scavenger was washed with heptane, dried and analyzed to determine the amount of carbon, nitrogen and sulfur (see Table 1).

TABLE-US-00001 TABLE 1 Spent analysis % C % N % S 30° C. 6.7 2.7 1.9 60° C. 7.1 2.6 2.1

Example 2

[0075] Other CS.sub.2-scavengers (structures 1, 3, 4, 5 from FIG. 2) containing different amine functionalities were prepared using different amine precursors in a similar way as described in Example 1. The thus prepared CS.sub.2-scavengers were also tested in the removal of CS.sub.2 from heptane. The preparation method and the CNS-analysis of the spent adsorbents are summarized in Table 2.

[0076] A material described in structures 6 and 7 in FIG. 2 can be envisaged to work as CS.sub.2-scavengers similarly.

TABLE-US-00002 TABLE 2 Struc- Preparation.sup.1) CNS of spent adsorbent.sup.2) ture NH.sub.2 Run (see Grafting Temp groups Carbon Nitrogen Sulfur no. FIG. 2) solvent ° C. mmol/g % % % 1 1 H.sub.2O 92 1.2  4.6 1.5 0.5 2 2 H.sub.2O 92 1.15 6.7 2.5 1.3 3 3 H.sub.2O 92 1.1  8.9 3.3 2.5 4 2 Methanol 35 1.19 6.3 2.5 2.2 5 2 Toluene 92 1.15 8.6 2.5 2.8 (dry) 6 4 H.sub.2O 92 1   11.3 2.6 2.9 7 5 Toluene 92 1.1  15.1 2.5 2.7 (dry) .sup.1)As described in Example 1; NH.sub.2 groups by mass balance .sup.2)Test conditions: 2 cc; 30° C.; 3 bar; LHSV = 6; 50 ppm S in heptane

Example 3

[0077] In another test, the selectivity of the CS.sub.2-scavenger (structure 2 in FIG. 2; 1.2 mmol —NH.sub.2/g) towards other sulfur-containing molecules was investigated.

[0078] In four different 20 ml flasks, 200 mg of the CS.sub.2-scavenger was mixed with 10 ml of heptane. To these flasks was subsequently added an 11-fold excess of CS.sub.2, ethyl sulfide, thiophene and propanethiol. The mixture was stirred at ambient temperature and pressure for 18 hours. After filtering and air drying, the carbon, nitrogen and sulfur content of the spent CS.sub.2-scavengers were analyzed (see Table 3.)

TABLE-US-00003 TABLE 3 Spent analysis Sulphur % C % N % S CS.sub.2 6.7 2.7 1.4 Propanethiol 6.7 2.7 <0.05 Ethyl sulphide 6.6 2.7 <0.05 Thiophene 6.6 2.7 <0.05

Example 4

[0079] In another test, a scavenger was prepared and tested on 1 to 3 mm spherical silica particles. (structure 2 in FIG. 2; 1.2 mmol —NH.sub.2/g)

[0080] 40.0 g of Perlkat 97-0 silica particles (1 to 3 mm), were mixed with 109 g demi-water in a 250 milliliter round bottom flask. Four droplets of surfactant (Dreft from P&G Professional) were added. While swirling the flask, 12.3 gram (55 mmol) of N-(3-(trimethoxysilyl)propyl)-ethylenediamine was dropwisely added. After addition, the flask was connected to a rotary evaporator and heated to 92° C. for 2 hours while rotating the flask at 60 rpm (no vacuum). The flask was then cooled to room temperature, the water layer decanted and the product was washed 3 times with 100 ml demi-water. Finally, the product was filtered and dried in an oven overnight at 105° C.

[0081] Analysis: LOI(105): 0.2 wt %. CNS: 5.6 wt % carbon, 2.6 wt % nitrogen, <0.05 wt % sulfur.

[0082] The CS.sub.2-scavenger was then tested in a fixed bed reactor. A bed of 10 ml of the CS.sub.2-scavenger particles prepared as described above (10 ml=5.4 g) was premixed with the same volume of inert material (SiC 0.5 mm granules=17 gram) and loaded in the reactor (diameter=9.1 mm; L=23.5 cm). A heptane feed containing 60 ppm CS.sub.2 (=50 ppm S) was started over the bed in upflow mode at 0.5 ml/min (LHSV=3) at ambient temperature and 3 barg pressure. Samples from the reactor were taken and analyzed for CS.sub.2 content by gas chromatography.

[0083] FIG. 3 shows the concentration of CS.sub.2 in heptane at the outlet of the reactor against hours on stream (10 cc adsorbent bed; LHSV=3/h; ambient T; 3 barg). The CS.sub.2 adsorption from heptane is show in FIG. 3. The data depicted in FIG. 3 show that the CS.sub.2 adsorbent performs surprisingly well even at 1 to 3 mm spherical silica particles at high space velocity.

[0084] After 140 hours on stream, the test was stopped. The adsorbent was isolated from the inert material. After air drying, the material was analyzed for CNS.

[0085] Analysis: CNS: 6.5 wt % carbon, 2.6 wt % nitrogen, 1.5 wt % sulfur.

Example 5

[0086] In a test using the CS.sub.2 scavenger from Example 4, 200 mg of scavenger was mixed with 10 ml heptane. To this mixture an 11-fold excess of CS.sub.2 was added. The mixture was stirred at ambient temperature and pressure for 18 hours. After filtering and air drying, the carbon, nitrogen and sulfur content of the spent CS.sub.2-scavengers were analyzed.

[0087] Analysis: CNS: 6.0 wt % carbon, 2.5 wt % nitrogen, 3.0 wt % sulfur.