Sulfur Detection at ppb Levels in Light Hydrocarbon Streams Based on a New Super Permeable PLOT Column Agilent Select Low Sulfur Johan Kuipers Channel Training Specialist Oct 12 th, 2010 1 October 18, 2010
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, Mercaptanes The 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? Response Low detection limits Linearity of response Inert sample flow path Selectivity Low detection limits Minimal detector quencing Loadability Low detection limits Large injection volumes 5 Confidentiality Label October 18, 2010
Requirements GC Columns for Sulfurs Which columns are available?
Excellent H2S response, poor selectivity PDMS, 30m x 0.32mm x 5μm CP-Sil 5CB - 30m*0.32mm*5.0µm 4500 4000 100 ppb H2S and COS, same response 1 2 1 100 ppb H 2 S 2 100 ppb COS 3500 3000 Excellent H2S recovery Analysis 30 C Detection PFPD Signal in µv 2500 2000 1500 1000 Co-elution C3= Leads to detector Quenching 500 0 0 0.5 1 1.5 2 2.5 3 3.5 4 Ret. Time
Excellent selectivity, poor response 5000 4500 4000 3500 1 SilicaPLOT Porous Silica 30m x 0.32mm 1 COS (± 100 ppb) 2 H 2 S (± 100 ppb) 3 Propane 4 Methyl mercaptan 1. 100 ppb COS 2. 100 ppb H2S 3. Propane (matrix) 4.Methylmercaptane Signal in µv 3000 2500 2000 1500 1000 500 2 < 60% H 2 S recovery 3 4 Analysis 100 C Detection PFPD 0 0 1 2 3 4 5 6 Ret. Time
Current GC column materials for H 2 S/COS Non-Polar Liquid Phase, PolyDimethylSiloxanes, Thick film 5μm Highly inert column with excellent H 2 S 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 H 2 S 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
Varian Select for Low Sulfur Sulfur components approx 100 ppb 4500 4000 3500 3000 Column: Oven: Flow: Inj: Det: Varian Select for Low Sulfur 60m x 0.32mm 65 C (6.5) --> 185 C, 2.0 ml/min He 50ul @ atmospheric split 1:50 PFPD PM signal in µv 2500 2000 H2S Ca. 100 ppb in N 2 ipm 1500 High response COS EM 1000 500 MM 0 0 2 4 6 8 10 12 14 16 18 Time [min]
Hydrocarbon elution profile on Select for Low Sulfur 20000 C2 C1 C4 Hydrocarbons selectivity signal [µv] 15000 C1 C2= C3= C3 C4's Column: Oven: Flow: Inj: Det: Varian Select for Low Sulfur 60m x 0.32mm 65 C (6.5) --> 185 C, 2.0 ml/min He 50ul @ atmospheric split 1:50 PFPD 10000 5000 AC MA PD 0 0 2 4 6 8 10 12 14 16 18 Time [min]
Sulfurs & HC s on Select Low Sulfur Select Low Sulfur - 60m*0.32mm Overlay of H 2 S, COS and Methyl mercaptan with hydrocarbons methane H 2 S ethane COS Propylene Conditions: Column: Temperature: 65 C Carrier Gas: Injector: 200 C Detector: PFPD Select Low Sulfur, 60m x 0.32mm Helium, constant flow 2 ml/min Air acetylene ethylene propane Methyl mercaptan 3 4 5 6 7 8 Time [min] Excellent separation COS/Propylene 13 Confidentiality Label October 18, 2010
Column Selectivity & Loadability H 2 S, COS and Methyl mercaptan in Propylene matrix Ca. 500 ppb H 2 S COS Conditions: Column: Temperature: 65 C Carrier Gas: Select Low Sulfur, 60m x 0.32mm Helium, constant flow 2 ml/min Injector: 200 C Detector: PFPD Inj. Volume: 1 ml, split 1:20 Propylene Methyl mercaptan 3 4 5 6 7 8 Time [min] 14 Confidentiality Label October 18, 2010
Low PPB Sulfur Levels 20 10 µv Select Low Sulfur 5209025_20_2.DATA 0-10 -20-30 -40-50 -60-70 Hydrogen sulfide Carbonyl sulfide -80-90 -100-110 -120-130 Methyl mercaptan -140-150 -160 RT [min] 3.6 3.8 4 4.2 4.4 4.6 4.8 5 5.2 5.4 5.6 5.8 6 6.2 6.4 6.6 6.8 7 7.2 7.4 7.6 7.8 8 Chromatogram of H 2 S with calculated ppb concentration of 21 ppb: 15 October 18, 2010
Linearity on Select Low Sulfur Linearity on the Select Low Sulfur column of active sulfurs using GC- PFPD 6.0 sqrt of Area counts [µv.min-1] 5.0 4.0 3.0 2.0 1.0 R² = 0.9981 R² = 0.9977 R² = 0.9972 H2S COS methyl mercaptan 0.0 0 10 20 30 40 50 60 Concentration in ppb Sample: gas mixture of H 2 S (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) 16 October 18, 2010
Repeatabilty on SCD 4000 3500 H2S, COS and MM on Select Low Sulfur using SCD 60 pg on column 3000 2500 H2S Area 2000 1500 1000 500 0 0 10 20 30 40 50 COS Methyl mercaptan Average area st dev Area % RSD H2S 3426 65 1.9% COS 3631 65 1.8% MM 3146 50 1.6% recovery 94% # of injections Conditions: Column: Select Low Sulfur, 60m x 0.32mm Temperature: 50 C for 8 minutes, with C/min to 185 C for 10 minutes Carrier Gas: Helium, constant flow 2 ml/min Injector: 200 C Detector: SCD, base temperature 200 C, burner temperature 800 C, oxidizer 65 ml/min, hydrogen 40 ml/min Sample: 250ul, split 1:60, 11 ppm 17 October 18, 2010
Sulfurs in Propane/propylene matrix TANK #2 8.93 PPM S as COS 8.93 PPM S as COS, 3.15 PPM S as H2S, 23.4% PROPANE, BALANCE PROPYLENE 1-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 Carrier Isothermal Oven at 40 C OI PFPD Optimized For Sulfur Detection (Linear Mode) 3.15 PPM S as H 2 S S/N 60 (Est. DL ~0.3 PPM) Propylene 23.4% Propane Courtesy: Laura Chambers, OI Analytical
Sulfurs in Ethane/Propane/Propylene matrix TANK #3 9.93 PPM S as COS 3.63 PPM S as H 2 S S/N 50 (Est. DL ~0.3 PPM) 9.93 PPM S as COS, 3.63 PPM S as H2S, 20.7% ETHANE, 1% PROPYLENE, BALANCE PROPANE 1-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 Carrier Isothermal Oven at 40 C OI PFPD Optimized For Sulfur Detection (Linear Mode) 20.7% Ethane 1% Propylene Propane Courtesy: Laura Chambers, OI Analytical
Conclusions Agilent J&W Select for Low Sulfur Linear response H 2 S,COS and MM at 20 200 ppb level One dimension, 60m x 0.32mm Best accuracy and repeatability Low ppb H 2 S 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