desulfurization of natural gas liquids

8/11/2019 Desulfurization of Natural Gas Liquids

1/21

DESULFURIZATION OF NATURAL GAS LIQUIDS

Main author

Gkhan Alptekin1

1TDA Research Inc

12345 W 52nd Avenue

Wheat Ridge, CO 80033

[email protected]

Co-authors

Richard Casavecchia22BP America Production Company

501 West Lake Park BlvdHouston, TX 77079

Ambal Jayaraman1

Matthew Schaefer1

John Monroe1

Kristin Bradley1


2/21

Page 2 of 21

Copyright 2008 IGRC2008

1. ABSTRACT

Natural Gas Liquids (NGLs) are sometimes contaminated with organic sulfur species like

mercaptans and dimethyl sulfides (DMS) after a conventional desulfurization step, with

the DMS concentrations as high as 500-1000 ppmw. In order for the NGLs to be apremium product, all forms of sulfur needs to be removed to low levels. Recently TDA

has developed a sorbent (SulfaTrapTM) for desulfurization of natural gas and liquefied

petroleum gas (LPG), which effectively removes sulfur-bearing odorants (e.g.,

thiophenes, mercaptans) with very high capacity. The sorbent is regenerated by

applying a mild temperature swing (by heating up the sorbent bed to 250-300oC), and

several consecutive adsorption/regeneration cycles were demonstrated. Molecular

theory and preliminary findings suggest that the same family of sorbents used for

natural gas and LPG also has the potential to remove sulfur species from higher

hydrocarbon fuels.

BP was interested in TDAs previous work and wanted to assess the performance of TDA

SulfaTrapTM sorbents for removal of DMS from NGLs in the presence of aromatics.

Hence, we modified the natural gas sorbent (SulfaTrapTM) and tailored it for the

desulfurization of NGLs. The SulfaTrapTM-R2A achieved a very high sulfur capacity

(greater than 1.5 % wt. S) using surrogate NGL mixtures (containing heavy

hydrocarbons including aromatic compounds) under representative conditions and

retained its capacity over 30 cycles. The sorbent could achieve even higher sulfur

capacities (up to 3.0% wt. S) in a C5/C6 hydrocarbon stream in the absence of

aromatics. This paper presents the comparison of the results obtained for

desulfurization of a NGL stream with TDAs sorbent (SulfaTrapTM-R2A) and a commercial

zeolite-13X sample in the presence of aromatics and also demonstrate the effect of the

concentration of the aromatic compounds on the sulfur capacity of the two sorbents. In

these tests, the SulfaTrapTM-R2A sorbent showed much better performance than the

commercial zeolite sample.


3/21

Page 3 of 21


C O N T E N T S

1. Abstract ................................................................................................. 2

2. Introduction........................................................................................... 4

3. Experimental.......................................................................................... 4

3.1. NGL Feed Mixtures.............................................................................................5

3.2. Sulfur Analysis ..................................................................................................5

4. Results and Discussion........................................................................... 6

4.1. Comparison of the zeolite-13X and SulfaTrapTM-R2A ...............................................6

4.2. Effect of aromatics .............................................................................................6

4.2.1. Zeolite 13X ..............................................................................................64.2.2. TDA SulfaTrapTM-R2A.................................................................................7

4.2.3. GC-MS Data................................................................................................74.3. Effect of Space Velocity ......................................................................................7

4.3.1. Zeolite 13X ..............................................................................................74.3.2. TDA SulfaTrapTM-R2A.................................................................................7

4.4. Multiple Cycle Tests ...........................................................................................8

4.4.1. Zeolite 13X ..............................................................................................84.4.2. TDA-SulfaTrapTM-R2A ...................................................................................8

4.5. Low Temperature TDA - SulfaTrapTM- R2AM Sorbent ...............................................8

4.6. High Mercaptan (Accelerated) Tests......................................................................9

4.7. Future Work......................................................................................................9

5. Summary................................................................................................ 9

6. References ............................................................................................. 9

7. List of Tables........................................................................................ 10

8. List of Figures ...................................................................................... 11


4/21

Page 4 of 21


2. INTRODUCTION

Natural Gas Liquids are the hydrocarbons that are separated from natural gas as liquids

either at the gas processing plants or in the field processing units. NGLs include ethane,

propane, butane, iso-butane and natural gasoline (mostly pentanes and heavierhydrocarbons). NGLs are valuable by-products of natural gas processing and are used

for enhancing oil recovery in oil wells, and also find use as a raw material and/or source

of energy for oil refineries and petrochemical plants. They are more valuable when used

as a petrochemical feedstock than as an energy source. Hence they are recovered from

natural gas streams as a liquid product and sold separately from the pipeline gas. The

NGLs are sometimes contaminated with organic sulfur species like mercaptans and

dimethyl sulfides (DMS). Conventionally caustic wash or solvent treatment is used to

remove sulfur species from NGLs. This absorption process removes H2S and the light

mercaptans from the NGLs but has shown ineffectiveness in removing DMS. The DMS

present in the NGLs after conventional desulfurization step sometimes could be as high

as 500-1000 ppmw as it concentrates in the C5 boiling range. In order for the NGLs to

be utilized as a premium by-product (such as utilization in gasoline pool), the sulfur

present in the form of DMS must be removed to low levels.

Adsorption is a viable technique for removing DMS from NGLs. 13X molecular sieve

(zeolite) adsorption of DMS has been discussed as an option (Harruff 1998). However,

the NGLs can also contain aromatic species like benzene, toluene, ethyl benzene and

xylenes in concentrations as high as 9.5 % on molar basis. Hence, the key challenge in

the desulfurization of NGLs by adsorption is to develop a sorbent that retains its

selectivity for organic sulfur species in the presence of aromatic compounds. Recently

TDA has developed sorbents (SulfaTrapTM R series) for the desulfurization of natural

gas and liquefied petroleum gas (LPG), where the sorbent effectively removed sulfur-

bearing natural gas odorants (e.g., thiophenes, mercaptans) with very high capacity,

and does so in the presence of aromatics and olefins. The sorbent can be regenerated

by applying a mild temperature swing (by heating up the sorbent bed to 250-300o

C).Molecular theory and preliminary findings suggests that this same family of sorbents

also has the potential to remove organic sulfur species from higher hydrocarbon fuels.

BP was interested in TDAs previous work and wanted to assess the performance of TDA

SulfaTrapTM sorbents for removal of DMS from NGLs in the presence of aromatics.

Hence, a modified version of the natural gas sorbent (SulfaTrapTM-R2A) was evaluated

for its potential use in desulfurization of NGLs. This paper presents the results of bench-

scale evaluations of the SulfaTrapTM-R2A sorbent and benchmarks the sorbents

performance to a commercial zeolite-13X molecular sieve. The impact of aromatic

compounds on the sulfur capacity of the two sorbents is particularly highlighted.

3. EXPERIMENTAL

We used an automated testing apparatus to carry out unattended flow experiments

through multiple-cycles under representative conditions. The unit is capable of testing

30 mL of sorbent samples in the form of cylindrical pellets (1/16). The test reactor was

in diameter and 6 in length. High temperature heat tapes wrapped around the

reactor were used to control the temperature and a high pressure liquid

chromatography (HPLC) pump was used to introduce the NGL to the test cell at the

desired flow rate. After passing through the reactor the NGL was vaporized in-line and


5/21

Page 5 of 21


sent to a HP-GC equipped with a flame photometric detector (FPD) to monitor the sulfur

breakthrough. The sorbent regeneration was carried out using a counter current flow of

an inert gas stream (N2). A valve system was in place to pass the regeneration gas

through the sorbent bed and flow directly to the analytical system for the analysis of the

regeneration products. The apparatus is fully automated and can run without an

operator for long periods of time, including overnight. We used Control EG software tocontrol test conditions, log analytical data, and to safely shut down the apparatus. The

test apparatus uses only Silcosteel (Restek) coated components to minimize sulfur

adsorption on the system components, such as transfer lines, gas manifolds. A coated

steel reactor allowed testing at elevated pressures. An automated sampling valve

provided sampling ability around the clock. After exiting the analytical system, the

effluent gas stream was sparged into an absorber solution where any sulfur in the gas

phase transferred into the solution and formed salts or acids to minimize their emissions

into the atmosphere.

3.1. NGL Feed Mixtures

After passing through traditional desulfurization processes, some NGL streams can

contain as high as 9.5% mol. aromatics and 1000 ppmw of total sulfur, which are

mostly DMS (95%) and some other heavier mercaptan and trace thiophenes. For

purposes of this testing, we lumped together the heavier sulphur components as n-

propyl mercaptan (PM). To support testing using a representative NGL stream, BP

supplied TDA with a simplified, custom C3+ NGL mixture (BP NGL mixture) based on

their operating experience. Table 1 shows the composition of BP NGL mixture. The

total sulfur and aromatics concentrations used in this mixture was 367 ppmw and 3.5%

mol. respectively. In addition to BPs NGL mixture, TDA prepared a simulated mixture

using hexane as the major component with 3.5% mol. toluene (TDA NGL mixture(1))

for use in long duration multiple cycle experiments. Also, in order to fully assess the

impact of heavy hydrocarbons and aromatics, TDA prepared another simulated mixture

(TDA NGL mixture(2)) with 8.6% mol. aromatics (with toluene, benzene, ethyl

benzene, and xylene at levels present in actual NGLs) in hexane. Table 2 and Table 3show the composition of TDA NGL mixture(1) and TDA NGL mixture(2), respectively.

3.2. Sulfur Analysis

The analysis of the sulfur compounds was carried out using a gas chromatograph

equipped with flame photometric detectors (FPD). FPD operates on the principle that

combusted sulfur emits light at a wavelength of 393 nm. The detector contains a photo

multiplier tube with a filter attached that allows only the sulfur light emission to be

detected. A capillary column was used to separate the sulphur compounds (RTX-5, 30

meter, 0.32 mm ID, with 1.0 micron film thickness manufactured by Restek

Corporation). A 0.5 mL sample loop was used to inject the vaporized NGL effluent from

the reactor on to the capillary column. The sulfur detection limit in these experimentswas approximately 0.1 ppmv. Figure 1 shows a sample chromatogram of the NGL feed

provided by BP (BP NGL mixture). In the zoomed in portion of the chromatogram, the

two well separated sulfur peaks for DMS and n-propyl mercaptan (PM) could be clearly

observed. We observed small baseline drifts for the hydrocarbons present in the NGL

feed. These baseline drifts were monitored to qualitatively assess the HC adsorption on

the sorbent surface. Although FPD is not designed to detect or measure hydrocarbon

species (HC), it proved to be a useful tool for qualitative assessment of HC adsorption

on the sorbents tested. We also used a gas chromatograph equipped with mass


6/21

Page 6 of 21


spectrometer to quantitatively assess the hydrocarbon adsorption on the benchmark

and the baseline sorbents.

4. RESULTS AND DISCUSSION

4.1. Comparison of the zeolite-13X and SulfaTrapTM-R2A

We tested the zeolite-13X sorbent in the BP-NGL mixture and the results are provided in

Figure 2. The zeolite-13Xsorbent achieved 0.4% wt. and 0.67% wt. sulfur capacity at 5

ppmw and 50 ppmw DMS breakthrough respectively. After regeneration under N2for 8

hours at 350oC the zeolite-13X sorbent also maintained a stable capacity. During

regeneration the desorption products were monitored with two DMS desorption peaks

observed at 150 and 350oC. Figure 3 shows the temperature programmed desorption

(TPD) profile for total sulfur under regeneration conditions. During regeneration in

addition to DMS and some amounts of PM (PM not fully removed from the sorbent at the

selected regeneration conditions) small amounts of PM derivatives (disulfides and other

dimers) were also observed. We also found that when high levels of aromatics are

present in the NGL feed the full regeneration of the zeolite-13X sorbent bed required

heating the bed to temperatures in excess of 350oC.

Under identical conditions, TDAs SulfaTrapTMR2A sorbent achieved over 1.5% wt.

sulfur capacity in the first 5 cycles with BP NGL mixture where the sorbent capacity was

measured at 50 ppmw DMS breakthrough (Figure 4); this is more than 2 times the

capacity of the zeolite-13X. The regeneration duration was between 4 8 hrs at 350 oC.

Figure 5 shows the TPD profile for total sulfur under regeneration conditions, indicating

that complete sorbent regeneration by heating the bed up to 425oC. During

regeneration in addition to DMS and PM desorption peaks, we also observed other sulfur

compounds (dimers and decomposition products).

The comparison of the zeolite 13X and SulfaTrapTM-R2A sorbents were carried out inboth the BP and TDA NGL feed mixtures at two different aromatic levels. TDAs

SulfaTrapTM-R2A sorbent outperformed the zeolite-13X sorbent and in general has more

than twice the sulfur capacity of zeolite-13X at 50 ppmw DMS breakthrough. In the BP

NGL mix with 3.5% aromatics TDAs SulfaTrapTM-R2A sorbent achieved 1.5% wt. sulfur

capacity compared to 0.7% wt. for zeolite-13X. In the TDA NGL mix(2) with 8.6%

aromatics zeolite-13X achieved only 0.2% wt. sulfur capacity compared to 0.5% wt. for

SulfaTrapTM-R2A sorbent (Figure 6).

4.2. Effect of aromatics

4.2.1. Zeolite 13XThe effect of aromatics content of the NGL stream on sulfur adsorption was studied both

for zeolite-13X and SulfaTrapTM-R2A sorbents. Figure 7 shows the DMS breakthrough on

the two TDA NGL mixtures at 3.5% and 8.6% mol. aromatics. There is a drop in

adsorption capacity from 0.28% wt. to 0.17% wt. with increase in aromatic

concentration. It is likely that the aromatic compounds compete for adsorption sites in

the zeolite-13X sorbent and reduce the available active sites for sulfur adsorption. This

assessment can be qualitatively confirmed by the baseline drifts observed in the FPD

data shown in Figure 8. Early in the adsorption step, the baseline drift due to toluene


7/21

Page 7 of 21


(residence time of 10.5 min) was not observed. The absence of this drift was attributed

to the adsorption of toluene on zeolite-13X sorbent. There is no evidence for adsorption

of other hydrocarbon species. It is expected that ethyl benzene and other aromatics

would too have a similar tendency to adsorb on the zeolite-13X.

4.2.2. TDA SulfaTrap

TM

-R2AFigure 9 shows the DMS breakthrough on the two TDA NGL feed mixtures at 3.5% and

8.6% mol. aromatics. There is only a marginal drop in adsorption capacity with increase

in aromatic concentration (which could be due to pore diffusion limitations for the high

aromatic NGL stream). There was no competition for adsorption sites from aromatic

compounds in SulfaTrapTM-R2A sorbent. The qualitative GC-FPD results indicated no

evidence of toluene or other hydrocarbon adsorption over SulfaTrapTM-R2A sorbent. As

shown in Figure 10 unlike the GC profiles for zeolite-13X sorbent, the toluene peak was

observed in the early chromatograms in the adsorption step (suggesting that it did not

adsorb on the sorbent). This shows that SulfaTrapTM-R2A is highly selective to sulfur,

which may be an advantage for high aromatic NGL feeds. The adsorption of other

aromatics like ethyl benzene, benzene and xylene is not expected on SulfaTrapTM-R2A.

4.2.3. GC-MS Data

The liquid samples collected in bench-scale tests using TDA-NGL mix were analyzed in a

GC-MS to confirm aromatic adsorption. The results from GC-MS analysis are shown in

Figure 11. The adsorption of aromatic hydrocarbons was evident on zeolite-13X sorbent

and no hydrocarbon adsorption was observed for the SulfaTrapTMsorbents. This shows

that the decline in performance with high aromatic NGL feeds in zeolite-13X is due to

competitive adsorption between aromatics and sulfur and the marginal decline in

SulfaTrapTM-R2A can be related to diffusion effects.

4.3. Effect of Space Velocity

4.3.1. Zeolite 13X

Figure 12 provides the effect of space velocity on the desulfurization of BP NGL mix.

We observed very little or no dependency on space velocity in the BP- NGL mix, which is

a light hydrocarbon mixture that contains lower amounts of aromatics (3.5% mol.). In

the case of TDA NGL mixture(1), which contains 3.5% mol. aromatics in hexane, the

space velocity has more impact (Figure 13). The sulfur capacity was significantly higher

at lower LHSV of 1.2 h-1compared to LHSV of 2.8 h-1. This dependence is likely due to

diffusion limitations in the heavier hexane fuel (i.e., larger resistance for the sulfur

compounds to diffuse through the NGL and reach the sorbent surface).

4.3.2. TDA SulfaTrapTM-R2A

Figure 14 provides the effect of space velocity on the desulfurization of BP NGL mix

using SulfaTrapTM-R2A sorbent. Similar to zeolite-13X sorbent, TDA SulfaTrapTM-R2A is

also microporous and shows a similar dependency (between capacity and space

velocity). In the case of TDA NGL mixture(2), which contains 8.6% mol. aromatics in

hexane, the effect of space velocity was highly visible (Figure 15) and significantly

higher sulfur capacity (0.46% wt. sulfur at breakthrough) was observed at lower space

velocity of 1.6 h-1compared to that at 4.5 h-1.


8/21

Page 8 of 21


4.4. Multiple Cycle Tests

4.4.1. Zeolite 13X

We carried out 31 adsorption/regeneration cycles. Between cycle #5 and cycle #28,

TDA NGL mixtures with 3.5% or 8.6% mol. aromatics with benzene/toluene/ethyl

benzene/xylene was used instead of the BP NGL mix with 3.5% mol. toluene. The

change was made to conserve the BP NGL mix and also to observe the effect of

aromatics because of the high aromatic adsorption in zeolite-13X. The zeolite-13X

sorbent was able to maintain a stable sulfur capacity of 0.75 wt. (26 mL/g of sorbent) at

50 ppmw DMS breakthrough with BP NGL mix after 31 cycles provided the

regenerations were carried out at 425oC temperature. When switched back from high

aromatic TDA-NGL (2) mix to low aromatic BP NGL mix (Cycle #27), the capacity

dropped by half (compared to Cycle#1 with BP NGL mix), likely due to heavy aromatic

adsorption during previous cycles. Once regenerated at 425oC for two cycles, the sulfur

capacity was restored to the initial cycle values. Figure 16 shows the DMS breakthrough

results for multiple cycle experiments and the summary of the breakthrough sulfur

capacities at 5 ppmw DMS breakthrough is reported in Figure 17.

4.4.2. TDA-SulfaTrapTM-R2A

We then carried out 31 cycles on TDA SulfaTrapTM-R2A sorbent. Between cycle #7 and

cycle #28 the feed was changed to TDA NGL mixtures with 3.5% or 8.6% mol.

aromatics with benzene/toluene/ethyl benzene/xylene in comparison to the BP NGL

mix with 3.5% mol. toluene only. The change was made to conserve the BP NGL mix

and also to observe the effect of aromatics. SulfaTrapTM-R2A was able to maintain a

stable sulfur capacity of 1.52 wt. (67 mL/g of sorbent) at 50 ppmw DMS breakthrough

with BP NGL mix after 31 cycles provided the regenerations were carried out at 425 oC

temperature. When switched back from high aromatic TDA NGL (2) to low aromatic BP

NGL (Cycle#29), the capacity drop is only marginal (compared to Cycle#1 with BP

NGL mix) and once extended regenerations were carried out at 425 oC the sulfur

capacity was restored to the initial cycle values. Figure 18 shows the DMS breakthroughresults for multiple cycle experiments and the summary of the breakthrough sulfur

capacities at 5 ppmw DMS breakthrough is reported in Figure 19.

4.5. Low Temperature TDA - SulfaTrapTM- R2AM Sorbent

Due to the importance of achieving full regenerations at low temperatures (e.g.,

reduced time needed for heating/cooling transitions, reduced heat input to support

sorbent regeneration) TDA also developed a modified version of its baseline sorbent

(SulfaTrapTM-R2AM) that can be regenerated at even lower temperatures. SulfaTrapTM-

R2AM (modified sorbent) achieves comparable performance with the baseline

SulfaTrapTM-R2A sorbent at 350oC regeneration temperature instead of a 425oC

regeneration temperature in both the BP and TDA NGL feed mixtures (Figure 20). TDAs

SulfaTrapTM-R2AM sorbent achieved 1.37% wt. sulfur capacity with BP NGL mixture (low

aromatics 3.5%) and 0.52% wt. sulfur capacity with TDA NGL mixture(2) (high

aromatics 8.6%) at 50 ppmw DMS breakthrough. The sorbent showed a stable

performance in an 8-cycle test. The results are presented in Figure 21. Figure 22 shows

the TPD profile for total sulfur under regeneration conditions, which shows that

complete sorbent regeneration could be achieved by heating the bed up to 350 oC.

During regeneration in addition to DMS and PM desorption peaks we also observed other

sulfur compounds (dimers and decomposition products) similar to the zeolite-13X and

SulfaTrapTM-R2A sorbents.


9/21

Page 9 of 21


4.6. High Mercaptan (Accelerated) Tests

In order to see the effect of various aromatic species and regeneration of PM we tested

the sorbents in high PM hydrocarbon mixtures containing up to 8.6% aromatics. To

expedite the tests we used 1,020 ppmw S as PM and 75 ppmw S as DMS in hexane and

the experiments were carried out at 2 psig and liquid samples were collected from the

reactor exit and analyzed for sulfur. Figure 23 shows the effect of the presence ofaromatics in the high PM feed mixture for zeolite-13X and SulfaTrapTM-R2A. Zeolite-13X

had a very high sulfur capacity (4.3% wt) in the absence of aromatics. In the presence

of aromatics the capacity dropped drastically and we observed a rollover of the sulfur

breakthrough curve (sulfur levels going above the inlet concentration) indicating that

the aromatic species are replacing the sulfur species and the sorbent is more selective

to aromatics than PM. In the case of SulfaTrapTM-R2A we did not observe any rollover of

sulfur breakthrough curves indicating the sorbent is selective to PM than aromatics and

the drop in capacity is only marginal when aromatic species were introduced. We also

observed dipropyl disulfide (DPDS) formation in both zeolite-13X and SulfaTrapTM-R2A

and it breaks through before both DMS and PM.

4.7. Future Work

As the next step, a larger scale test rig will be installed temporarily on site to run a

slipstream of actual plant feed over 120-cycles. This will help us with scale up to

commercial size as well as avoid potential surprises with feed components that we have

not considered in this study.

5. SUMMARY

We have developed very effective sorbents (SulfaTrapTM-R2A and SulfaTrapTM-R2AM) for

the desulfurization of natural gas liquids that are highly selective to sulfur species in the

presence of aromatics. These sorbents could be used to desulfurize the high sulfur NGLs

and convert them to a valuable product.

TDAs SulfaTrapTM-R2A sorbent achieves a sulfur capacity of 1.52% wt. in BP-NGL

Mix, which is more than twice the adsorption capacity of zeolite-13X (0.66% wt.).

It also achieved more than twice the adsorption capacity of zeolite-13X in high

aromatic NGL (0.46% Vs 0.17%).

Both SulfaTrapTM-R2A and zeolite-13X sorbents require a regeneration temperature

of 425oC to maintain stable capacity.

The modified sorbent SulfaTrapTM-R2AM has a similar sulfur capacity to SulfaTrapTM-

R2A and it can be regenerated at a much lower temperature (350oC).

We observed disulfide formation in both zeolite-13X and TDA sorbents in high

mercaptan environment.

TDA sorbents retained their superior performance in high mercaptan and high

aromatic NGL feeds.

6. REFERENCES

1. Harruff, L.G.; Martinie, G.D.; Rahman, A. Oil & Gas Journal1998, 96 (41), 72-76.


10/21


11/21

Page 11 of 21


8. LIST OF FIGURES

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.0010.0011.0012.0013.0014.000

500000

1000000

1500000

2000000

2500000

3000000

3500000

4000000

4500000

5000000

5500000

6000000

6500000

7000000

7500000

8000000

8500000

9000000

9500000

Time

Response_

RUN-24.D\FPD2B

View Mode: Integration

Time (min)

FPDS

ignal

1.0x107

PM

DMS

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.0010.0011.0012.0013.0014.000

500000

1000000

1500000

2000000

2500000

3000000

3500000

4000000

4500000

5000000

5500000

6000000

6500000

7000000

7500000

8000000

8500000

9000000

9500000

Time

Response_

RUN-24.D\FPD2B


Time (min)

FPDS

ignal

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.0010.0011.0012.0013.0014.000

500000

1000000

1500000

2000000

2500000

3000000

3500000

4000000

4500000

5000000

5500000

6000000

6500000

7000000

7500000

8000000

8500000

9000000

9500000

Time

Response_

RUN-24.D\FPD2B


Time (min)

FPDS

ignal

1.0x107

PM

DMS

Gas ChromatogramBP-NGL Mixture

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.0010.0011.0012.0013.0014.000

500000

1000000

1500000

2000000

2500000

3000000

3500000

4000000

4500000

5000000

5500000

6000000

6500000

7000000

7500000

8000000

8500000

9000000

9500000

Time

Response_

RUN-24.D\FPD2B


Time (min)

FPDS

ignal

1.0x107

PM

DMS

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.0010.0011.0012.0013.0014.000

500000

1000000

1500000

2000000

2500000

3000000

3500000

4000000

4500000

5000000

5500000

6000000

6500000

7000000

7500000

8000000

8500000

9000000

9500000

Time

Response_

RUN-24.D\FPD2B


Time (min)

FPDS

ignal

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.0010.0011.0012.0013.0014.000

500000

1000000

1500000

2000000

2500000

3000000

3500000

4000000

4500000

5000000

5500000

6000000

6500000

7000000

7500000

8000000

8500000

9000000

9500000

Time

Response_

RUN-24.D\FPD2B


Time (min)

FPDS

ignal

1.0x107

PM

DMS


0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.0011.0012.0013.0014.00

40000

42000

44000

46000

48000

50000

52000

54000

56000

58000

60000

62000

64000

66000

68000

70000

72000

74000

76000

Time

Response_

RUN-24.D\FPD2B

Time (min)

FPDS

ignal

8.0x104

Pentane

Propane

Butane

Propyl Mercaptan (PM)

Heptane Toluene

Di-Methyl Sulfide (DMS)

Hexane

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.0011.0012.0013.0014.00

40000

42000

44000

46000

48000

50000

52000

54000

56000

58000

60000

62000

64000

66000

68000

70000

72000

74000

76000

Time

Response_

RUN-24.D\FPD2B

Time (min)

FPDS

ignal

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.0011.0012.0013.0014.00

40000

42000

44000

46000

48000

50000

52000

54000

56000

58000

60000

62000

64000

66000

68000

70000

72000

74000

76000

Time

Response_

RUN-24.D\FPD2B

Time (min)

FPDS

ignal

8.0x104

Pentane

Propane

Butane


Heptane Toluene


Hexane

(Zoomed In)


0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.0011.0012.0013.0014.00

40000

42000

44000

46000

48000

50000

52000

54000

56000

58000

60000

62000

64000

66000

68000

70000

72000

74000

76000

Time

Response_

RUN-24.D\FPD2B

Time (min)

FPDS

ignal

8.0x104

Pentane

Propane

Butane


Heptane Toluene


Hexane

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.0011.0012.0013.0014.00

40000

42000

44000

46000

48000

50000

52000

54000

56000

58000

60000

62000

64000

66000

68000

70000

72000

74000

76000

Time

Response_

RUN-24.D\FPD2B

Time (min)

FPDS

ignal

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.0011.0012.0013.0014.00

40000

42000

44000

46000

48000

50000

52000

54000

56000

58000

60000

62000

64000

66000

68000

70000

72000

74000

76000

Time

Response_

RUN-24.D\FPD2B

Time (min)

FPDS

ignal

8.0x104

Pentane

Propane

Butane


Heptane Toluene


Hexane

(Zoomed In)


DMS

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.0010.0011.0012.0013.0014.000

500000

1000000

1500000

2000000

2500000

3000000

3500000

4000000

4500000

5000000

5500000

6000000

6500000

7000000

7500000

8000000

8500000

9000000

9500000

Time

Response_

RUN-24.D\FPD2B


Time (min)

FPDS

ignal

1.0x107

PM

DMS

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.0010.0011.0012.0013.0014.000

500000

1000000

1500000

2000000

2500000

3000000

3500000

4000000

4500000

5000000

5500000

6000000

6500000

7000000

7500000

8000000

8500000

9000000

9500000

Time

Response_

RUN-24.D\FPD2B


Time (min)

FPDS

ignal

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.0010.0011.0012.0013.0014.000

500000

1000000

1500000

2000000

2500000

3000000

3500000

4000000

4500000

5000000

5500000

6000000

6500000

7000000

7500000

8000000

8500000

9000000

9500000

Time

Response_

RUN-24.D\FPD2B


Time (min)

FPDS

ignal

1.0x107

PM

DMS


0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.0010.0011.0012.0013.0014.000

500000

1000000

1500000

2000000

2500000

3000000

3500000

4000000

4500000

5000000

5500000

6000000

6500000

7000000

7500000

8000000

8500000

9000000

9500000

Time

Response_

RUN-24.D\FPD2B


Time (min)

FPDS

ignal

1.0x107

PM

DMS

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.0010.0011.0012.0013.0014.000

500000

1000000

1500000

2000000

2500000

3000000

3500000

4000000

4500000

5000000

5500000

6000000

6500000

7000000

7500000

8000000

8500000

9000000

9500000

Time

Response_

RUN-24.D\FPD2B


Time (min)

FPDS

ignal

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.0010.0011.0012.0013.0014.000

500000

1000000

1500000

2000000

2500000

3000000

3500000

4000000

4500000

5000000

5500000

6000000

6500000

7000000

7500000

8000000

8500000

9000000

9500000

Time

Response_

RUN-24.D\FPD2B


Time (min)

FPDS

ignal

1.0x107

PM

DMS


0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.0011.0012.0013.0014.00

40000

42000

44000

46000

48000

50000

52000

54000

56000

58000

60000

62000

64000

66000

68000

70000

72000

74000

76000

Time

Response_

RUN-24.D\FPD2B

Time (min)

FPDS

ignal

8.0x104

Pentane

Propane

Butane


Heptane Toluene


Hexane

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.0011.0012.0013.0014.00

40000

42000

44000

46000

48000

50000

52000

54000

56000

58000

60000

62000

64000

66000

68000

70000

72000

74000

76000

Time

Response_

RUN-24.D\FPD2B

Time (min)

FPDS

ignal

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.0011.0012.0013.0014.00

40000

42000

44000

46000

48000

50000

52000

54000

56000

58000

60000

62000

64000

66000

68000

70000

72000

74000

76000

Time

Response_

RUN-24.D\FPD2B

Time (min)

FPDS

ignal

8.0x104

Pentane

Propane

Butane


Heptane Toluene


Hexane

(Zoomed In)


0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.0011.0012.0013.0014.00

40000

42000

44000

46000

48000

50000

52000

54000

56000

58000

60000

62000

64000

66000

68000

70000

72000

74000

76000

Time

Response_

RUN-24.D\FPD2B

Time (min)

FPDS

ignal

8.0x104

Pentane

Propane

Butane


Heptane Toluene


Hexane

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.0011.0012.0013.0014.00

40000

42000

44000

46000

48000

50000

52000

54000

56000

58000

60000

62000

64000

66000

68000

70000

72000

74000

76000

Time

Response_

RUN-24.D\FPD2B

Time (min)

FPDS

ignal

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.0011.0012.0013.0014.00

40000

42000

44000

46000

48000

50000

52000

54000

56000

58000

60000

62000

64000

66000

68000

70000

72000

74000

76000

Time

Response_

RUN-24.D\FPD2B

Time (min)

FPDS

ignal

8.0x104

Pentane

Propane

Butane


Heptane Toluene


Hexane

(Zoomed In)


DMS

Figure 1. Sample Chromatogram in GC-FPD with BP-NGL Mixture.

BP - NGL Mix Desulfurization

Zeolite - 13X Cycling Data

N2- regen @350oC 8 h

0

2

4

6

8

10

12

14

0 5 10 15 20 25

mL NGL Desulfurized/g of Sorbent

DMSconcn

.(ppmw)

Cycle #1

Cycle #2

Cycle #3

Cycle #4

Cycle #5

Figure 2. BP NGL mixture desulfurization at T = 40oC and P = 150 psia

on zeolite-13X.


12/21

Page 12 of 21


0 100 200 300

Time (min)

FPDSarea

0

50

100

150

200

250

300

350

400

Temperature,

oC

Total Sulfur

Reactor Temp.

2.5x109

Figure 3. TPD profile for zeolite-13X after sulfur adsorption from BP-NGL mixture.


SulfaTrapTM-R2A Cycling Data

0

20

40

60

80

100

120

140

0 20 40 60 80 100


DMSconcn.

(ppm

w)

Cycle #1

Cycle #2

Cycle #3

Cycle #5

Figure 4. BP NGL mixture desulfurization at T = 40oC and P = 150 psia

on SulfaTrapTM-R2A.


13/21

Page 13 of 21


0 200 400 600 800 1000

Time (min)

FPDSarea

0

50

100

150

200

250

300

350

400

450

Temperature,

oC

Total Sulfur

Reactor Temp.

4.0x109

Figure 5. TPD profile for SulfaTrapTM-R2A after sulfur adsorption from BP-NGL mixture.


3.5% aromatics

0

20

40

60

80

100

120

140

0 20 40 60 80 100


DMSconcn

.(ppmw) Zeolite-13X

SulfaTrap-R2A

TDA - NGL Mix Desulfurization

8.6% aromatics

0

100

200

300

400

500

600

0 10 20 30 40


DMSconc

n.

(ppmw)

Zeolite-13X

SulfaTrap-R2A

Figure 6. Comparison of zeolite-13X Vs SulfaTrapTM-R2A sorbent in low aromatic

and high aromatic NGL at T = 40oC, P = 150 psia, LHSV = 4 h-1and T = 40oC,

P = 135 psia, LHSV = 2.8 h-1respectively.


14/21

Page 14 of 21



Zeolite - 13X

LHSV = 2.8 h-1

0

100

200

300

400

500

600

0 10 20 30 40


DMSconcn.

(ppm

w)

3.5% aromatics

8.6% aromatics

Figure 7. Effect of aromatics on zeolite-13X sorbent for TDA NGL feeds at T = 40oC, P = 135

psia and LHSV = 2.8 h-1.

1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.0010.0011.0012.0013.0014.00

43800

43900

44000

44100

44200

44300

44400

44500

44600

44700

44800

44900

45000

45100

45200

45300

45400

45500

45600

45700

45800

45900

46000

Time

Response_

RUN-02.D\FPD2B

Time (min)

Pentane

Propane

Butane

Heptane

Hexane

FPDS

ignal

5.0x104

1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.0010.0011.0012.0013.0014.00

43800

43900

44000

44100

44200

44300

44400

44500

44600

44700

44800

44900

45000

45100

45200

45300

45400

45500

45600

45700

45800

45900

46000

Time

Response_

RUN-02.D\FPD2B

Time (min)

Pentane

Propane

Butane

Heptane

Hexane

FPDS

ignal

5.0x104

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.0010.0011.0012.0013.00

43400

43600

43800

44000

44200

44400

44600

44800

45000

45200

45400

45600

45800

46000

46200

46400

46600

46800

47000

Time

Response_

RUN-10.D\FPD2B

Time (min)

Pentane

Propane

Butane

Heptane

Hexane

FPDS

ignal

5.0x104

Toluene

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.0010.0011.0012.0013.00

43400

43600

43800

44000

44200

44400

44600

44800

45000

45200

45400

45600

45800

46000

46200

46400

46600

46800

47000

Time

Response_

RUN-10.D\FPD2B

Time (min)

Pentane

Propane

Butane

Heptane

Hexane

FPDS

ignal

5.0x104

Toluene

t = 125 min, ~ 13.1 mL/g fuel treated


Figure 8. Toluene adsorption on zeolite-13X sorbent as seen in FPD Signal for desulfurization of

BP NGL mix at T = 40oC, P = 150 psia.


15/21

Page 15 of 21



SulfaTrapTM-R2A

LHSV = 2.0 h-1

0

100

200

300

400

500

600

0 5 10 15 20 25


DMSconcn.

(ppm

w)

3.5% aromatics

8.6% aromatics

Figure 9. Effect of aromatics on SulfaTrapTM-R2A sorbent for TDA NGL feeds

at T = 40oC, P = 135 psia and LHSV = 2.0 h-1.

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.0011.0012.0013.0014.00

43000

43200

43400

43600

43800

44000

44200

44400

44600

44800

45000

45200

45400

45600

45800

46000

46200

46400

46600

46800

47000

47200

47400

47600

47800

Time

Response_

RUN-02.D\FPD2B


Time (min)

Pentane

Propane

Butane

HeptaneHexane

FPDS

ignal

5.0x104

Toluene

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.0011.0012.0013.0014.00

43000

43200

43400

43600

43800

44000

44200

44400

44600

44800

45000

45200

45400

45600

45800

46000

46200

46400

46600

46800

47000

47200

47400

47600

47800

Time

Response_

RUN-02.D\FPD2B


Time (min)

Pentane

Propane

Butane

HeptaneHexane

FPDS

ignal

5.0x104

Toluene


0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.0010.0011.0012.0013.0014.00

40000

42000

44000

46000

48000

50000

52000

54000

56000

58000

60000

62000

64000

66000

68000

70000

72000

74000

76000

Time

Response_

RUN-24.D\FPD2B

Time (min)

FPDS

ignal

8.0x104

Pentane

Propane

Butane


Heptane Toluene


Hexane

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.0010.0011.0012.0013.0014.00

40000

42000

44000

46000

48000

50000

52000

54000

56000

58000

60000

62000

64000

66000

68000

70000

72000

74000

76000

Time

Response_

RUN-24.D\FPD2B

Time (min)

FPDS

ignal

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.0010.0011.0012.0013.0014.00

40000

42000

44000

46000

48000

50000

52000

54000

56000

58000

60000

62000

64000

66000

68000

70000

72000

74000

76000

Time

Response_

RUN-24.D\FPD2B

Time (min)

FPDS

ignal

8.0x104

Pentane

Propane

Butane


Heptane Toluene


Hexane

t = 0 min, Feed mixture

Figure 10. Sulfur Selectivity for SulfaTrapTM-R2A sorbent as seen in FPD Signal for

desulfurization of BP NGL mix at T = 40oC, P = 150 psia.


16/21

Page 16 of 21


Zeolite-13X

0

0.2

0.4

0.6

0.8

1

1.2

0 5 10 15 20 25

mL NGL Desulfurized/g sorbent

NormalizedHydrocarbonpeak

AreafromG

C-M

S

Benzene

Toluene

Ethyl Benzene

Xylene

SulfaTrapTM-R2A

0

0.2

0.4

0.6

0.8

1

1.2

0 5 10 15 20


TotalSulfurConcn.(ppmw

S)

Benzene

Toluene

Ethyl Benzene

Xylene

Figure 11. Comparison of GC-MS data showing adsorption of aromatics

for zeolite-13X and SulfaTrapTM-R2A.


Zeolite - 13X

0

2

4

6

8

10

12

14

0 5 10 15 20 25 30


DMSconcn.

(ppmw)

LHSV = 4.0 h-1

LHSV = 1.5 h-1

Figure 12. Effect space velocity on desulfurization of BP NGL mix at

T = 40oC and P = 150 psia on zeolite-13X sorbent.


Zeolite - 13X 3.5% aroma tics

0

100

200

300

400

500

600

0 10 20 30 40 50


DMS

concn.(ppmw)

LHSV = 2.8 h-1

LHSV = 1.2 h-1

Figure 13. Effect space velocity on desulfurization of TDA NGL mix(1) at

T = 40oC and P = 135 psia on zeolite-13X sorbent.


17/21

Page 17 of 21



SulfaTrapTM-R2A

0

2

4

6

8

10

12

14

0 20 40 60 80


DMSconcn.

(ppmw)

LHSV = 6.7 h-1

LHSV = 3.5 h-1

Figure 14. Effect space velocity on desulfurization of BP NGL mix at

T = 40oC and P = 150 psia on SulfaTrapTM-R2A sorbent.


SulfaTrapTM-R2A

8.6% aromatics

0

100

200

300

400

500

600

0 10 20 30 40 50


DMSconcn.

(ppmw)

LHSV = 1.6 h-1LHSV = 4.5 h-1

Figure 15. Effect space velocity on desulfurization of TDA NGL mix(2) at

T = 40oC and P = 135 psia on SulfaTrapTM-R2A sorbent.


18/21

Page 18 of 21



Zeolite - 13X Cycling Data

0

2

4

6

8

10

12

14

0 5 10 15 20 25


DMSconcn.

(ppm

w) Cycle #1

Cycle #2Cycle #3

Cycle #4

Cycle #5

Cycle #27

Cycle #28 - 425C

Cycle #29 - 425C

Cycle #30

Cycle #31

Figure 16. DMS breakthrough in the multiple cycle test on zeolite-13X at

T = 40oC, P = 150 psia and LHSV = 1-4 h-1.

Figure 17. Summary of 30-cycle test with zeolite-13X (benchmark sorbent).


19/21

Page 19 of 21



SulfaTrap

TM

-R2A Cycling Data

0

20

40

60

80

100

120

140

0 20 40 60 80 100


DMSconcn.

(ppmw) Cycle #1

Cycle #2

Cycle #3

Cycle #5

Cycle #29 -

8hrs@425CCycle #30 -

12hrs@425CCycle #31 -

LHSV 1.1 (1/h)

Figure 18. DMS breakthrough in the multiple cycle test on SulfaTrapTM-R2A at

T = 40oC, P = 135-150 psia and LHSV = 1-7 h-1.

Breakthrough at 5 ppmw DMS

0.0%

0.4%

0.8%

1.2%

1.6%

2.0%

0 10 20 30 40Cycle #

TotalSLoading(%

wt.S)

BP-NGL Mix

TDA-NGL Mix-1

TDA-NGL Mix-2

Figure 19. Summary of 30-cycle test with SulfaTrap

TM

-R2A (baseline sorbent).


20/21

Page 20 of 21



3.5% aromatics

0

100

200

300

400

500

600

700

800

0 20 40 60 80 100 120


DMSconcn

.(ppmw)

SulfaTrap-R2AM

SulfaTrap-R2A


8.6% aromatics

0

100

200

300

400

500

600

0 10 20 30 40 50


DMSconcn

.(ppmw)

SulfaTrap-R2AM

SulfaTrap-R2A

Figure 20. Comparison of SulfaTrapTMsorbents in low aromatic and high aromatic NGL at T =

40oC, P = 135-150 psia.

SulfaTrapTM-R2AM Cycling Data

0

2

4

6

8

10

12

14

0 10 20 30 40 50 60


DMSconcn.

(ppmw)

Cycle #2 BP-NGL (3.5% aromatics)

Cycle #3 BP-NGL (3.5% aromatics)

Cycle #5 TDA-NGL (8.6% aromatics)

Cycle #8 TDA-NGL (8.6% aromatics)

Figure 21. DMS breakthrough in multiple cycle test on SulfaTrapTM-R2AM.at

T = 40oC, P = 135-150 psia and LHSV = 0.9-4.5 h-1.


21/21

Page 21 of 21

0 100 200 300 400 500

Time (min)

FPDSarea

0

50

100

150

200

250

300

350

400

Temperature,

oC

Total Sulfur

Reactor Temp.

5.0x109

Figure 22. TPD profile for SulfaTrapTM-R2AM Sorbent.

Zeolite-13X

0

300

600

900

1200

1500

1800

2100

0 20 40 60 80 100


TotalSulfurConcn.

(ppmw

S)

Hexane/Toluene/Benzene/EB/Xylene

(8.6% aromatics)

Hexane (no aromatics)

SulfaTrapTM-R2A

0

200

400

600

800

0 5 10 15 20 25 30


TotalSulfurConcn.

(ppmw

S)

Hexane/Toluene/Benzene/EB/Xylene

(8.6% aromatics)

Hexane (no aromatics)

Figure 23. Comparison of zeolite-13X and SulfaTrapTM-R2A sorbents in high mercaptan feeds at

T = 40oC, P = 2 psig, LHSV = 4 h-1, DMS = 75 ppmw S, PM = 1020 ppmw S.

desulfurization of natural gas liquids

Documents