Sulfur Detection at ppb Levels in Light

Hydrocarbon Streams

Based on a New Super Permeable PLOTColumn

Agilent Select Low Sulfur

Johan KuipersChannel Training Specialist

Oct 12th, 2010

October 18, 20101

Sulfur compounds in refinery streams

Boiling point range of the feedstock determines presence type of sulfurs

•H2S•COS•Mercaptans•Thiophenes•Disulfides•Sulfides

Sulfur compounds even at < 100ppb level

•Poison Ziegler-Natta, Metallocene catalysts

•Drastically reduce the polymer yield of polyolefin feeds

Propylene, polypropylene

Sources of Propylene for polypropylene feed

• Refinery Fluidized Catalytic Cracking (FCC) byproduct• Ethylene Cracking Furnaces, byproduct of ethylene production• Propane catalytic dehydration

Refinery FCC byproduct is by far the largest source

Ethylene, Propylene Matrix

Low ppb level detection of H2S, COS, MercaptanesThe major challenges:

•Absorption of H2S and mercaptanes on active surfaces– Stability of calibration standards– Sample introduction path– Possible GC column absorption

•Sensitive sulfur specific detection required– Pulsed Flame Photometric Detector (PFPD)– Sulfur Chemiluminescence Detector (SCD)– Atomic Emission Detector (AED), limited sensitivity– Quenching due to co-eluting hydrocarbon species, matrix

What is needed of GC column for Sulfur Analysis?

October 18, 2010Confidentiality Label

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Response

Selectivity Loadability

Low detection limitsLinearity of responseInert sample flow path

Low detection limitsMinimal detector quencing

Low detection limitsLarge injection volumes

Requirements GC Columns for Sulfurs

Which columns are available?

Excellent H2S response, poor selectivity

CP-Sil 5CB - 30m*0.32mm*5.0µm

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Ret. Time

Sign

al in

µV

1 100 ppb H2S 2 100 ppb COS

12

PDMS , 30m x 0.32mm x 5μm

Analysis 30°CDetection PFPD

Excellent H2S recovery

100 ppb H2S and COS, same response

Co-elution C3=Leads to detectorQuenching

Excellent selectivity, poor response

SilicaPLOT

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nal

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1

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4

1 COS (± 100 ppb)2 H2S (± 100 ppb)3 Propane4 Methyl mercaptan

3

1. 100 ppb COS2. 100 ppb H2S3. Propane (matrix)4.Methylmercaptane

Analysis 100°CDetection PFPD

< 60% H2S recovery

Porous Silica 30m x 0.32mm

Current GC column materials for H2S/COS

Non-Polar Liquid Phase, PolyDimethylSiloxanes, Thick film 5μm•Highly inert column with excellent H2S responses•Not selective, COS/propylene co-elutes, detector quencing

Porous polymer PLOT columns•Absorption of H2S at low ppm levels•H2S/COS and propylene well separated

Porous Silica, PLOT columns•COS/ethylene,propylene well separated•H2S/ethylene, propylene well separated•Absorption of H2S at low ppb levels

All these columns either exhibit a poor selectivity or a poor H2S response

Agilent J&W Select for Low Sulfur

Agilent J&W Select for Low Sulfur•Near 100% recovery for H2S at ppb levels•Excellent sulfur selectivity for propylene matrices•Excellent prospects for ethylene matrices•PFPD, SCD, AED Compatible

•Porous Layer Open Tubelar (PLOT) column•Super Permeable & Porous Stationary Phase

– proprietary material•Zero particle loss•Dimension 60m x 0.32mm

Sulfur components approx 100 ppb

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Time [min]

signa

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H2S

COS

MM

EM

iPM

PMColumn: Varian Select for Low Sulfur

60m x 0.32mmOven: 65°C (6.5) --> 185°C, Flow: 2.0 ml/min HeInj: 50ul @ atmospheric

split 1:50Det: PFPD

Ca. 100 ppb in N2

High response

Varian Select for Low Sulfur

Hydrocarbon elution profile on Select for Low Sulfur

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C2

C4'sC3

C3=

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MA

AC

C2=

Column: Varian Select for Low Sulfur60m x 0.32mm

Oven: 65°C (6.5) --> 185°C, Flow: 2.0 ml/min HeInj: 50ul @ atmospheric

split 1:50Det: PFPD

C1 – C4 Hydrocarbons selectivity

Sulfurs & HC’s on Select Low Sulfur

October 18, 2010Confidentiality Label

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3 4 5 6 7 8Time [min]

Select Low Sulfur - 60m*0.32mmOverlay of H2S, COS and Methyl mercaptan with hydrocarbons

H2S C

OS P

ropy

lene

Met

hyl m

erca

ptan

met

hane

etha

ne

ethy

lene

Air

acet

ylen

e

prop

ane

Conditions:Column: Select Low Sulfur,

60m x 0.32mmTemperature: 65°C Carrier Gas: Helium, constant

flow 2 mL/minInjector: 200°CDetector: PFPD

Excellent separation COS/Propylene

Column Selectivity & Loadability

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3 4 5 6 7 8Time [min]

H2S, COS and Methyl mercaptan in Propylene matrix

H2SCOS

Propylene Methyl mercaptan

Conditions:Column: Select Low Sulfur,

60m x 0.32mmTemperature: 65°C Carrier Gas: Helium, constant

flow 2 mL/minInjector: 200°CDetector: PFPDInj. Volume: 1 mL, split 1:20

Ca. 500 ppb

Low PPB Sulfur Levels

October 18, 201015

87.87.67.47.276.86.66.46.265.85.65.45.254.84.64.44.243.83.6

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Hydro

gen s

ulfid

e

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onyl sulfid

e

Meth

yl m

erc

apta

n

RT [min]

Select Low Sulfur 5209025_20_2.DATAµV

Chromatogram of H2S with calculated ppb concentration of 21 ppb:

Linearity on Select Low Sulfur

October 18, 201016

R² = 0.9981

R² = 0.9977

R² = 0.9972

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sqrt

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rea

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Concentration in ppb

Linearity on the Select Low Sulfur column of active sulfurs using GC-PFPD

H2S

COS

methyl mercaptan

Sample: gas mixture of H2S (11.4 ppm), COS (11.3 ppm) and MM (11.6 ppm) in N2.Sample loop: 1 ml, Variable split ratio’s (1:40 – 1:110)

Repeatabilty on SCD

October 18, 201017

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H2S, COS and MM on Select Low Sulfur using SCD

H2S

COS

Methyl mercaptan

Conditions:Column: Select Low Sulfur, 60m x 0.32mmTemperature: 50°C for 8 minutes, with °C/min to 185°C for 10 minutes Carrier Gas: Helium, constant flow 2 mL/minInjector: 200°CDetector: SCD, base temperature 200°C, burner temperature 800°C, oxidizer 65 mL/min,

hydrogen 40 mL/minSample: 250ul, split 1:60, 11 ppm

Average area

st dev Area

% RSD

H2S 3426 65 1.9%COS 3631 65 1.8%MM 3146 50 1.6%

recovery 94%

60 pg on column

8.93 PPM S as COS

3.15 PPM S as H2SS/N 60

(Est. DL ~0.3 PPM)23.4% Propane

Propylene

TANK #2

8.93 PPM S as COS, 3.15 PPM S as H2S, 23.4% PROPANE, BALANCE PROPYLENE1-mL Gas Sample Loop, 50:1 Split Ratio, Inject Time 0.2 Minute Varian Beta Low Sulfur, 30-m X 0.32-mm ID, 1 mL/min He CarrierIsothermal Oven at 40 °COI PFPD Optimized For Sulfur Detection (Linear Mode)

Courtesy: Laura Chambers, OI Analytical

Sulfurs in Propane/propylene matrix

9.93 PPM S as COS

3.63 PPM S as H2SS/N 50

(Est. DL ~0.3 PPM)Propane

1% Propylene

TANK #3

20.7% Ethane

9.93 PPM S as COS, 3.63 PPM S as H2S, 20.7% ETHANE, 1% PROPYLENE, BALANCE PROPANE1-mL Gas Sample Loop, 50:1 Split Ratio, Inject Time 0.2 Minute Varian Beta Low Sulfur, 30-m X 0.32-mm ID, 1 mL/min He CarrierIsothermal Oven at 40 °COI PFPD Optimized For Sulfur Detection (Linear Mode)

Sulfurs in Ethane/Propane/Propylene matrix

Courtesy: Laura Chambers, OI Analytical

Conclusions

Agilent J&W Select for Low Sulfur

•Linear response H2S,COS and MM at 20 – 200 ppb level

•One dimension, 60m x 0.32mm

•Best accuracy and repeatability

•Low ppb H2S detection limits in propylene

•Mechanically stable PLOT column, zero particle loss

•Introduction December 2010, tentative

Acknowledgement

•Helena Jacobse, Agilent Technologies. The Netherlands

•Frans Biermans, Agilent Technologies. The Netherlands

•Laura Chambers, OI Analytical

Sulfur Detection at ppb Levels in Light Hydrocarbon StreamsSulfur compounds in refinery streamsPropylene, polypropyleneEthylene, Propylene MatrixWhat is needed of GC column for Sulfur Analysis?Requirements GC Columns for SulfursExcellent H2S response, poor selectivityExcellent selectivity, poor responseCurrent GC column materials for H2S/COSAgilent J&W Select for Low SulfurVarian Select for Low SulfurHydrocarbon elution profile on Select for Low SulfurSulfurs & HC’s on Select Low SulfurColumn Selectivity & LoadabilityLow PPB Sulfur LevelsLinearity on Select Low SulfurRepeatabilty on SCDSlide Number 18Slide Number 19ConclusionsAcknowledgement