METHODS FOR REGENERATING SOLID ADSORBENTS

Field of the Invention

[0001] The invention provides a method for regenerating solid adsorbents used to separate 2- chloro-3,3,3-trifluoropropene (HCFO-1233xf) from 2-chloro-l,l,l,2-tetrafluorpropane (HCFC-244bb) , including spent solid adsorbents comprising activated carbon and molecular sieves. HCFO-1233xf can be desorbed, recovered, and recycled.

Background of the Invention

[0002] Hydrofluoroolefins (HFOs), such as tetrafluoropropenes, including 2,3,3,3- tetrafluoropropene (HFO-1234yf), are known to be effective refrigerants, heat transfer media, propellants, foaming agents, blowing agents, gaseous dielectrics, sterilant carriers, polymerization media, particulate removal fluids, carrier fluids, buffing abrasive agents, displacement drying agents and power cycle working fluids. Unlike chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), both of which potentially damage the Earth's ozone layer, HFOs do not contain chlorine and thus pose no threat to the ozone layer. HFO-1234yf has also been shown to be a low global warming compound with low toxicity and, hence, can meet increasingly stringent requirements for refrigerants in mobile air conditioning. Accordingly, compositions containing HFO-1234yf are among the materials being developed for use in many of the aforementioned applications.

[0003] One manufacturing process for HFO-1234yf uses 1, 1, 2, 3-tetrachloropropene (1230xa) as starting raw material. The process comprises the following three steps:

Step (1): 1230xa + 3HF -> 2-chloro-3,3,3,-trifluoropropene (1233xf) + 3HC1 in a vapor phase reactor charged with a solid catalyst,

Step (2): 1233xf + HF -> 2-chloro-l,l,l,2-tetrafluoropropane (HCFC-244bb) in a liquid phase reactor charged with a liquid catalyst; and

Step (3): 244bb --> 1234yf + HC1 in a vapor phase reactor.

[0004] In Step (2), the conversion of 1233xf is often incomplete, and some 1233xf is carried over to Step (3) along with 244bb. The presence of 1233xf in the Step (3) feed is undesired inasmuch as it renders various advantageous recycles problematic, and raises the potential for unwanted side reactions, among other things. Separating 1233xf from 244bb is thus preferred. U.S. Published Patent Application No. 2013/0085308 relates that activated carbon, used to separate 1233xf from 244bb, can be regenerated by heating, vacuum or an inert gas stream. Regenerating the activated carbon is economically important. Nonetheless, other methods of regenerating activated carbon, and of regenerating other adsorbents useful for separating 1233xf from 244bb, are desired.

Summary of the Invention

[0005] In one aspect, the invention is to a method of regenerating a solid adsorbent used in separating 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf) from 2-chloro-l,l,l,2- tetrafluorpropane (HCFC-244bb), preferably a spent solid adsorbent, such as a molecular sieve or an activated carbon, using stable fluorinated hydrocarbons compounds, as regeneration fluids. In preferred embodiments, saturated hydrofluorocarbons are used as regeneration fluids. Useful examples of said fluorinated hydrocarbons included, but are not limited to, HFC-245cb (1,1,1,2,2-pentafluoropropane), HFC-245fa (1,1,1,3,3- pentafluoropropane), HCF-245eb (1,1,1,2,3-pentafluoropropane), HFC-245ea (1,1,2,3,3- pentalfuoropropane), HFC-245ca (1,1,2,2,3-pentafluoropropane), HFC-236ea (1,1,1,2,3,3- hexafluoropropane), HFC-236fa (1,1,1,3,3,3-hexafluoropropane), HFC-236cb (1,1,1,2,2,3- hexafluoropropane), HFC-236ca (1, 1,2,2,3, 3-hexafluoropropane), HFC-254fa (1,1,3,3- tetrafluoropropane), HFC-254fb (1, 1,1,3-tetrafluoropropane), HFC-254eb (1, 1,1,2- tetrafluoropropane), HFC-254cb (1,1,2,2-tetrafluoropropane), HFC-254ca (1,2,2,3- tetrafluoropropane), HFC-254ea (1,1,2,3-tetrafluoropropane), HFC-263fa (1,1,3- trifluoropropane), HFC-263fb (1,1,1-trifluoropropane), HFC-263ea (1,2,3-trifluoropropane), HFC-263eb (1,1,2-trifluoropropane), HFC-263ca (1,2,2-trifluoropropane), HFC-272fa (1,3- difluoropropane), HFC-272ea (1,2-difluoropropane), HFC-272ca (2,2-difluoropropane), HFC-272fb (1,1-difluoropropane), HFC-281fa (1-fluoropropane), HFC-281ea (2- fluoropropane), HFC-218 (octafluoropropane), HFC-227ca (1, 1, 1,2,2,3,3- heptafluoropropane), HFC-227ea (1,1, 1,2,3,3,3-heptafluoropropane), HFC-116 (1,1,1,2,2,2- hexafluoroethane), HFC-134 (1, 1,2,2-tetrafluoroethane), HFC-134a (1,1,1,2- tetrafluoroethane), HFC-125 (1,1, 1,2,2-pentafluoroethane), HFC-143 (1,1,2-trifluoroethane), HFC-143a (1, 1,1-trifluoroethane), HFC-152 (1,2-difluoroethane), HFC-152a (1,1- difluoroethane), HFC-161 (fluoroethane), FC-14 (tetrafluoromethane), HFC-23 (trifluoromethane), HFC-32 (difluoromethane), HFC-41 (fluoromethane), and mixtures thereof, as regeneration fluids.

Brief Description of the Drawings

[0006] Figure 1 graphically depicts the comparative performance of fresh and regenerated activated carbon (Calgon OLC 12X40) for 1233xf adsoption where the regeneration is by nitrogen purge gas at 150° C, 200° C, and 250° C for the time frames indicated. (Feed composition: 97.6957 GC area% 244bb/2.3043 GC area% 1233xf; 50 ml of adsorbent; room temperature; atmosphere pressure)

[0007] Figure 2 graphically depicts the comparative performance of fresh and regenerated activated carbon (Calgon OLC 12X40) for 1233xf adsoption where the regeneration is by vacuum at 150° C, 200° C, and 250° C. at the time frames indicated. (Feed composition: 97.6957 GC area% 244bb/2.3043 GC area% 1233xf; 50 ml of adsorbent; room temperature; atmosphere pressure)

[0008] Figure 3 graphically depicts the comparative performance of fresh and regenerated activated carbon (Calgon OLC 12X40) for 1233xf adsoption where the regeneration is by the organic 1,1,1,3,3-pentafluoropropane (245fa) purge at 150° C, 200° C, and 250° C. at the time frames indicated (Feed composition: 97.6957 GC area% 244bb/2.3043 GC area% 1233xf; 50 ml of adsorbent; room temperature; atmosphere pressure).

[0009] Figure 4 graphically depicts the comparative performance of fresh and regenerated activated carbon (Calgon OLC 12X40) for 1233xf adsoption where the regeneration is by the organic 1,1,1,2,2-pentafluoropropane (245cb) purge at 150° C, 200° C, and 250° C. at the time frames indicated (Feed composition: 97.6957 GC area% 244bb/2.3043 GC area% 1233xf; 50 ml of adsorbent; room temperature; atmosphere pressure).

Detailed Description of the Invention

[0010] In one embodiment, the invention relates to a method of regenerating a solid adsorbent used in separating 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf) from 2-chloro- 1,1,1,2-tetrafluorpropane (HCFC-244bb) wherein the solid adsorbent contains 2-chloro-3,3,3- trifluoropropene (HCFO-1233xf). The method of regenerating comprises contacting at least a portion of the solid adsorbent with a fluorinated hydrocarbon compound under conditions effective to desorb at least a portion of the HCFO- 1233xf. Regeneration can occur at any time as known in the art, preferably when the adsorbent is at or near saturation; that is to say, when the adsorbent is spent or near being spent.

[0011] Suitable solid adsorbents include, without limitation, molecular sieves, carbon molecular sieves, and activated carbons. Molecular sieves that are serviceable in separating 2- chloro-3,3,3-trifluoropropene (HCFO-1233xf) and 2-chloro-l,l, l,2-tetrafluorpropane (HCFC-244bb) include, without limitation, those having a pore size of 5 A or greater. Such molecular sieves include, without limitation, zeolites such as 13X, ZSM-5, H-ZSM-5, MFI or silicalite (an Al-free version of ZMS-5), and combinations thereof. In a preferred practice, the pore size is 5.5A or greater. More preferably, the pore size is 5.5A to 10 A. Other preferred pore sizes include 6A, 6.5A, 7A, 7.5A, 8A, 8.5A, 9A, 9.5A, and all ranges in between. The most preferred pore size is about 10A. The adsorption can occur under static or flow conditions. As used herein, the term molecular sieve includes carbon molecular sieves, such as those derived from natural materials such as coal or from man-made polymers such as discussed in U.S. Patent Nos. 4,820,681 and 6,670,304 and US Publication No.

2002/0025290. It will be understood that the term sorb and its cognates (e.g. adsorbent) as used herein includes the act of adsorption, absorption and the like, and is not limited to any particular type of adsorption or absorption in any physical or thermodynamic sense. The term is intended to encompass whatever processes or mechanism, or combinations thereof, are present, by which HCFO-1233xf and HCFC-244bb are separated.

[0012] Carbon molecular sieves useful in the present invention include, without limitation, those derived from natural materials such as coal or from man-made polymers such as discussed in U.S. Patent Nos. 4,820,681 and 6,670,304 and US Publication No.

2002/0025290. These carbon molecular sieves are distinguished from activated carbons, which are also derived from natural materials but have much larger pore sizes. The carbon molecular sieves useful for the separation described herein have an exemplary pore size of 5.0 A or greater.

[0013] Serviceable activated carbons include coconut shell based activated carbon, a coal based activated carbon, or combinations thereof. In certain embodiments, the activated carbon is designed by the manufacturer for use in vapor phase applications. In certain embodiments, the activated carbon is designed by the manufacturer for use in liquid phase applications. Calgon Carbon Corporation of Pittsburgh, Pa. manufactures and sells a number of such activated carbons, including products having the following designations; BPL, RVG, OVC, COCO, AT-410, and VPR, as examples. [0014] One parameter used to characterize activated carbons is the Iodine Number. The Iodine Number is generally used as a measure of activity level, a higher number indicates a higher degree of activation, and it also serves as an indicator of the micropore content of the activated carbon. The Iodine Number is defined as the milligrams of iodine adsorbed by one gram of carbon when the iodine concentration in the residual filtrate is 0.02 normal.

[0015] In the present invention, activated carbons having a minimum Iodine Number of 900 are expected to sorb at least a portion of the olefin impurities. Activated carbons having a minimum Iodine Number of 1000 are expected to sorb more of the olefin impurities.

Activated carbons having a minimum Iodine Number of 1100 are expected to sorb even more of the olefin impurities. Finally, activated carbons having a minimum Iodine Number of 1200 are expected to sorb still more of the olefin impurities. Other solid adadsorbents having properties similar to those of the activated carbons are also expected to be useful herein.

[0016] In one practice, the fluorinated hydrocarbon compound is selected from the group consisting of HFC-245cb (1,1,1,2,2-pentafluoropropane), HFC-245fa (1,1,1,3,3- pentafluoropropane), HCF-245eb (1,1,1,2,3-pentafluoropropane), HFC-236ea (1,1, 1,2,3,3- hexafluoropropane), HFC-134a (1,1, 1,2-tetrafluoroethane), HFC-125 (1, 1,1,2,2- pentafluoroe thane), and mixtures thereof. HFC-245cb is preferred as the predominant or sole regenerating fluid. In one practice, HFC-245cb is obtained as a by-product of Step (2) shown above and can be conveniently used as the regenerating fluid. Inert gases can be used in admixture with the fluorinated hydrocarbons.

[0017] The temperature at which regeneration is below that which will cause reactions with the fluorinated organics to occur, or otherwise, but must be high enough to allow desorption to occur. For activated carbons, a preferred temperature is about 100°C to 300°C, more preferably about 150° C. to about 250° C. When the adsorbent is a molecular sieve as described herein the temperature is preferably about 50° C. to about 250° C, more preferably about 100° C. to about 200° C.

[0018] In another embodiment, the HCFO-1233xf can be desorbed by techniques known in the art, for example, by degassing, including by vacuum. The desorbed HCFO-1233xf can be collected afterward and repurposed, such as recycle. In certain practices, the desorbed HCFO- 1233xf also comprises at least a portion of the fluorinated organic compound used for regeneration. The desorbed HCFO-1233xf can be separated from this fluorinated organic compound, for example by distillation, and the HCFO-1233xf thereafter recovered. All or a portion of the recovered HCFO-1233xf can be recycled, for example, back to Step (2) of the HFO-1234yf process shown above. [0019] The another embodiment, the invention is to a method of preparing 2,3,3,3- tetrafluoropropene (HFO-1234yf) comprising contacting a first intermediate composition comprising 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf) with HF in the presence of a fluorination catalyst under conditions effective to produce a second intermediate composition comprising 2-chloro-l, l,l,2-tetrafluorpropane (HCFC-244bb) and unreacted HCFO-1233xf; separating the unreacted HCFO-1233xf from the HCFC-244bb by contacting the second intermediate composition with a solid adsorbent under conditions effective such that the solid adsorbent sorbs the unreacted HCFO-1233xf thereby separating it from at least a portion of the HCFC-244bb; regenerating the solid sorbent by contacting the solid sorbent with a fluorinated hydrocarbon compound under conditions effective to desorb at least a portion of the HCFO-1233xf; and dehydrochlorinating at least a portion of the HCFC-244bb separated in step (b) to produce a reaction product comprising HFO-1234yf.

[0020] The following examples are illustrative only and are not limiting to the present invention.

Example 1

[0021] A cylindrical Monel reactor of ¾" diameter immersed into a 3 -zone electrical furnace was used in all of the experiments of adsorption tests. Process temperatures were recorded using a multi -point thermocouple placed inside the reactor and within the solid adsorbent bed. The distance between two adjacent probe points was 4". The solid adsorbent was loaded in such a way that its bed was within three adjacent probe points. The solid adsorbent was dried in nitrogen flow for 4 hours at 200° C. After drying step, the reactor was cooled down to room temperature (typically between 20° and 30° C). 244bb feed was then fed into the bottom of the vertically mounted reactor and was vaporized before reaching the bed of solid adsorbent. Effluent gases were periodically analyzed by means of gas chromatograph (GC) to determine the adsorption efficiency of each adsorbent.

[0022] Various molecular sieves were tested for adsorbing 1233xf included in 244bb feed with a 244bb feed containing 2.304 GC area% 1233xf. The capacity of each adsorbent was calculated based on individual isothermal adsorption curve and the results are presented in Table 1. The molecular sieve 13X showed the highest adsorption capacity (ca. 1.6 wt% of its own weight). Table 2 presents the performance of 13X. During the effective period of time (where the adsorption percentage of 1233xf was > 95%), the 1233xf concentration in effluent stream was below 1000 ppm.

Table 1 Capacity of various molecular sieves for adsorbing 1233xf at room temperature and atmosphere pressure*

* Feed composition: 97.6957 GC area% 244bb/2.3043 GC area% 1233xf; 50 ml of adsorbent

Table 2 Performance of 13X molecular sieve during 1233xf adsorption at room temperature and atmosphere pressure*

* Feed composition: 97.6957 GC area% 244bb/2.3043 GC area% 1233xf; 50 ml of adsorbent

Example 2

[0023] The same set-up and procedure as in Example 1 were used in Example 2. Various activated carbons (AC) were tested for adsorbing 1233xf included in 244bb feed with a 244bb feed containing 2.304 GC area% 1233xf. The capacity of each adsorbent was calculated based on individual isothermal adsorption curve and the results are presented in Table 3. Calgon OLC 12X40 AC showed the highest adsorption capacity (ca. 5.3 wt% of its own weight). Table 4 presents the performance of Calgon OLC 12X40 AC. During the effective period of time (where the adsorption percentage of 1233xf was > 95%), the 1233xf concentration in effluent stream was below 1000 ppm. Table 3 Capacity of various carbons for adsorbing 1233xf at room temperature and atmosphere pressure

Table 4 Performance of Calgon OLC 12X40 AC during 1233xf adsorption at room temperature and atmosphere pressure*

11 - 12 5.2 0.0591 99.8635 0.0775 96.6 0.1158

12 - 13 5.2 0.0167 98.5792 1.4041 39.1 0.0468

13 - 14 5.3 0.0082 98.0500 1.9418 15.7 0.0192

14 - 15 5.1 0.0067 97.9688 2.0245 12.1 0.0143

15 - 16 5.1 0.0058 97.9276 2.0666 10.3 0.0121

16 - 17 5.4 0.0053 97.7773 2.0891 9.3 0.0116

17 - 18 5.3 0.0053 97.8879 2.1067 8.6 0.0105

18 - 19 5.2 0.0047 97.8258 2.1695 5.8 0.0070

19 - 20 5.5 0.0049 97.7875 2.2076 4.2 0.0053

20 - 21 5.2 0.0047 97.7436 2.2516 2.3 0.0027

21 - 22 5.3 0.0042 97.7569 2.2389 2.8 0.0035

22 - 23 5.2 0.0042 97.7495 2.2463 2.5 0.0030

* Feed composition: 97.6957 GC area% 244bb/2.3043 GC area% 1233xf; 50 ml of adsorbent

Example 3

A cylindrical Monel reactor of ¾" diameter immersed into a 3 -zone electrical furnace was used in this adsorption tests using carbon molecular sieves. Process temperatures were recorded using a multi-point thermocouple placed inside the reactor and within the solid adsorbent bed. The distance between two adjacent probe points was 4". The solid adsorbent was loaded in such a way that its bed was within three adjacent probe points. The solid adsorbent was dried in nitrogen flow for 4 hours at 200° C. After drying step, the reactor was cooled down to room temperature (typically between 20° and 30° C). 244bb feed was then fed into the bottom of the vertically mounted reactor and was vaporized before reaching the bed of solid adsorbent. Effluent gases were periodically analyzed by means of gas chromatograph (GC) to determine the adsorption efficiency of each adsorbent.

Various carbon molecular sieves were tested for adsorbing 1233xf included in 244bb feed with a 244bb feed containing 2.3043 GC area% 1233xf. The capacity of each adsorbent was calculated based on individual isothermal adsorption curve and the results are presented in Table 5. The X2M4/6 showed the highest adsorption capacity (ca. 6.2 wt% of its own weight). Table 6 presents the performance of X2M4/6 carbon molecular sieve. During the effective period of time (where the adsorption percentage of 1233xf was > 95%), the 1233xf concentration in effluent stream was below 1000 ppm.

Table 5 Capacity of various carbon molecular sieves for adsorbing 1233xf at room temperature and atmosphere pressure*

* Feed composition: 97.6957 GC area% 244bb/2.3043 GC area% 1233xf; 50 ml of adsorbent

Table 6 Performance of X2M4/6 carbon molecular sieve during 1233xf adsorption at room temperature and atmosphere pressure*

13 - 14 5.1 0.0381 98.511 1.4509 25.6254 0.0276

14 - 15 4.9 0.0336 98.363 1.6034 17.8081 0.0184

15 - 16 5.0 0.0301 98.2906 1.6793 13.9174 0.0147

16 - 17 5.0 0.0278 98.2391 1.7331 11.1595 0.0118

17 - 18 5.1 0.0259 98.1925 1.7815 8.6785 0.0094

18 - 19 5.1 0.0244 98.1692 1.8065 7.3970 0.0080

19 - 20 5.1 0.0254 98.1349 1.8397 5.6951 0.0061

20 - 21 5.0 0.0237 98.125 1.8512 5.1056 0.0054

21 - 22 5.1 0.0242 98.1068 1.8689 4.1983 0.0045

22 - 23 5.1 0.0231 98.0325 1.9444 0.3281 0.0004

* Feed composition: 97.6957 GC area% 244bb/2.3043 GC area% 1233xf; 40 ml of adsorbent

Example 4

[0024] After reaching adsorption saturation over the Calgon OLC 12X40 AC in Example 2, the regeneration of the spent Calgon OLC 12X40 AC was first conducted in nitrogen flow by ramping temperature to 150° C. and holding at the same temperature for 2.5h. After regeneration and cool down, the adsorption experiment was re-started at room temperature. The regeneration at 200° C. and 250° C. was done similarly. As shown in Figure 1, the spent AC was regenerable with N2 as purging gas and required a temperature > 200° C.

Example 5

[0025] One issue associated with using nitrogen as purging gas for regeneration is the material loss during the recovery of adsorbed 244bb and 1233xf due to its difficulty to be condensed. Regeneration of the spent Calgon OLC 12X40 AC was then conducted under vacuum by ramping temperature to 150° C, 200° C, or 250° C. and holding at the same temperature for an extended period of time. A YELLOW JACKET Pump (Model 93540), which can pull a vacuum down to 15 microns, was used to pull the vacuum. As shown in Figure 2, the linear increase period for 1233xf adsorption was shorter after the regeneration under vacuum than that after the regeneration in nitrogen flow. Neverthess, similar to the regeneration with N2 as purging gas, the regeneration under vacuum required a temperature > 200° C. as well. Example 6

[0026] A regeneration method was used, in which purging (desorption) step was conducted with 1,1,1,3,3-pentafluoropropane (245fa) as purging agent. As shown in Figure 3, the length of the linear increase period for 1233xf adsorption after regeneration in 245fa flow at each of three temperatures (150° C, 200° C, and 250° C.) tested was almost the same as the fresh activated carbon. This indicates after each cycle of regeneration, the length of operation time is almost the same as the fresh activated carbon.

[0027] Example 7

A regeneration method was used, in which purging (desorption) step was conducted with 1,1,1,2,2-pentafluoropropane (245cb) as purging agent. As shown in Figure 4, the length of the linear increase period for 1233xf adsorption after regeneration in 245cb flow at each of three temperatures (150° C, 200° C, and 250° C.) tested was almost the same as the fresh activated carbon. This indicates after each cycle of regeneration, the length of operation time is almost the same as the fresh activated carbon. Other hydrofluorocarbons such as 245eb, 236ea, 125, 134a are used as purging gases during regeneration, and similar results are achieved. Table 7 presents the performance of regenerated Calgon OLC 12X40 AC. One can see during the effective period of time (where the adsorption percentage of 1233xf was > 95%), the 1233xf concentration in effluent stream was below 1000 ppm.

Table 7 Performance of regenerated Calgon OLC 12X40 AC during 1233xf adsorption at room temperature and atmosphere pressure*

6-7 4.9 0.0055 99.9904 0.0041 99.8221 0.1127

7-8 5.6 0.0051 99.9949 0.0000 100.0000 0.1290

8-9 5.5 0.0056 99.9944 0.0000 100.0000 0.1267 -10 5.5 0.0060 98.0910 0.1849 91.9759 0.11660-11 5.4 0.0036 98.3491 1.6473 28.5119 0.03551 - 12 5.6 0.0025 97.8440 2.1535 6.5443 0.00842-13 5.3 0.0000 97.8126 2.1862 5.1252 0.00633 - 14 5.3 0.0000 97.7811 2.2189 3.7061 0.0045

0-1 3.4 0.9372 98.9511 0.1117 95.1525 0.0745

1-2 5.5 0.4447 99.4409 0.1145 95.0310 0.1204

2-3 5.3 0.0110 99.9572 0.0319 98.6156 0.1204

3-4 5.5 0.0375 99.9555 0.0070 99.6962 0.1264

4-5 5.6 0.2150 99.9597 0.0188 99.1841 0.1280

5-6 5.2 0.0069 99.9595 0.0338 98.5332 0.1181

6-7 5.2 0.0075 99.9888 0.0037 99.8394 0.1196

7-8 5.6 0.0090 99.9458 0.0451 98.0428 0.1265

8-9 5.8 0.0114 99.9854 0.0032 99.8611 0.1335 -10 5.3 0.0097 99.3474 0.6429 72.1000 0.08810-11 5.2 0.0055 98.0420 1.9524 15.2714 0.01831 - 12 5.6 0.0045 97.9183 2.0773 9.8511 0.01272-13 5.2 0.0041 97.8986 2.0973 8.9832 0.01083 - 14 5.7 0.0033 97.8205 2.1761 5.5635 0.00734- 15 5.7 0.0028 97.8411 2.1561 6.4315 0.0084

0-1 2.2 0.0390 99.8529 0.0328 98.5766 0.0000

1-2 5.1 0.0206 99.9489 0.0122 99.4706 0.0504

2-3 5.2 0.0200 99.9727 0.0067 99.7092 0.1172

3-4 5.0 0.0164 99.9800 0.0000 100.0000 0.1198 4-5 5.0 0.0120 99.9836 0.0000 100.0000 0.1152

5-6 4.5 0.0090 99.9880 0.0000 100.0000 0.1152

6-7 5.2 0.0090 99.9910 0.0000 100.0000 0.1037

7-8 5.5 0.0073 99.9910 0.0000 100.0000 0.1198

8-9 5.1 0.0067 99.9927 0.0000 100.0000 0.1267

9-10 5.7 0.0081 99.9933 0.0000 100.0000 0.1175

10-11 5.3 0.0055 99.9537 0.0382 98.3422 0.1292

11 - 12 5.4 0.0042 98.7224 1.2721 44.7945 0.0547

12-13 5.5 0.0038 98.1693 1.8265 20.7351 0.0258

13 - 14 5.5 0.0034 98.1138 1.8824 18.3092 0.0232

* Feed composition: 97.6957 GC area% 244bb/2.3043 GC area% 1233xf; 50 ml of adsorbent

[0028] The foregoing description is by way of example only and is not limiting to the scope of the invention.