Bonded High retentive and selective Silica PLOT column for analyzing hydrocarbons and halogenated compounds

Transcription

1 Bonded High retentive and selective Silica PLOT column for analyzing hydrocarbons and halogenated compounds J. de Zeeuw, B.Bromps, T. Vezza and G. Stidsen Restek Corporation

2 Problems in the field Need shorter run times for gases and volatiles Need selective adsorbent materials as capillary column Present solutions have limited application and stability

3 Separation of volatiles Need Retention Retention is generated by: Partition chromatography using thick films like Rtx-1, 5.. problem is that plates decrease rapidly if films > 1 micron Adsorption chromatography using alumina, Q-BOND.. About 50x more retention Surface interactions, very efficient, high plate counts

4 Strategy for fast analysis The α has biggest impact on the Resolution Practical approach for reducing analysis time: 1 Maximize α 2 Optimize column dimensions 3 Set operational Parameters

5 Refinery gas on Rt Alumina BOND/ Na2SO4 0 Column : 50m x 0.53mm Al2O3/Na2SO4 BOND df = 6 μm Oven : 45ºC (1min), 10ºC/min to 200ºC (3.5) Injection : Split Injection; 80 ml/min; 200ºC Detector : FID, 200ºC Carrier gas : H2, 57 kpa, 8 psi pentenes Methane 2. Ethane 3. Ethylene 4. Propane 5. Propylene 6. Iso-butane 7. n-butane 8. Propadiene 9. Acetylene 10. Trans-2-butene butene 12. Iso-butylene 13. Cis-2-butene 14. Iso-pentane 15. n-pentane 16. 1,3-butadiene 17. Trans-2-pentene methyl-2-butene pentene 20. cis-2-pentene

6 Aluminium Oxide Limitations

7 Alumina columns: Limitations T max = 200C, Above 200C polarity changes; Not for all halogenated components Reactivity for 1,2 Butadiene, Pentadienes Highly sensitive for water Adsorbs sulfur and all oxygenated compounds

8 Activity of alumina Surface: 1,2 butadiene at 150ºC Dimerization of of 11,2-BD 11,2-BD while while traveling through through the the column column

9 Impact of halogenated hydrocarbons: Repeated injections of C4 hydrocarbon with 5% methyl chloride.. 11 TRACE GC-B BH23564F TRACE GC-B Lyo ndell TRACE GC-B Lyondell TRACE GC-B Lyondell Unstable baseline developes caused by MeCl reactivity.. 7 Millivolts 6 6 Millivolts Injection without mecl Minutes

10 Impact of water

11 Impact of water Original retention propyne i-c5 C5 1,3-BD FID1 A, (I:\R_MORE~1\WATER\TEST0014.D) counts After water exposure of ng H2O min propyne i-c5 C5 1,3-BD min

12 Water & alumina Often there is some water in the sample stream: Retention changes Selectivity changes To work with this Use temperature program to 200/250C to remove water: Takes a lot of extra time Time depends on amount of water Conditioning when the peaks are out of the window Use polar Rtx-Wax pre-column with valve (complex)

13 Problem makers for alumina Impacting retention Water Alcohols, ethers, polars CO2, NH3, Sulfurs Oils, heavy hydrocarbons

14 Silica adsorbent Is already available under names like Gaspro or SilicaPLOT, both from Agilent group; Also available as: silica Gel packed columns

15 Challenges for existing silica based PLOT solutions Sensitivity for water: retention time and selectivity Temperature stability and response reproducibility Elution of sulfur components Fragility availability

16 New Silica based PLOT: Rt-Silica BOND Very Stable layer, no particles Water minimally impacts retention times Better peak shape for sulfurs and halo carbons Minimal Reactivity

17 Silca BOND: stable porous layer No particle release Reproducible flow behavior Also usable in switching and MS systems

18 Silica adsorbent: hydrocarbon separations: what is different from alumina? Different selectivity then alumina Unique separations Higher temperature range Easier to elute heavier hydrocarbons Higher inertness Elutes sensitive hydrocarbons like 1,2 BD, pentadiene Elutes halocarbons, ethers, ketones and sulfurs

19 Hydrocarbons C1 C3, 30m x 0.32mm 80 e th a ne ethy len e a ce ty len e p rop an e acetylene propane 60 m e th a ne p ro py len e propylene 40 Methyl acetylene m e th yl ac e ty le n e min

20 Peak shape acetylene Propane

21 C1 - C5 hydrocarbons

22 C4 - C5 hydrocarbons Complete Different separation compared with alumina

23 Hydrocarbon Linearity for methyl acetylene

24 Activity of alumina Surface: 1,2 butadiene at 150ºC Dimerization of of 11,2-BD 11,2-BD while while traveling through through the the column column

25 1,2 butadiene at 150ºC on silica surface Column : 15m x 0.32mm Silica Oven : 150ºC Carrier : H2, 5 psi Split : 80 ml/min Injection : split, temp. 250ºC Detection : FID No decomposition/reactivity for 1,2 BD Time (min)

26 Silica Allows correct measurement of reactive hydrocarbons like 1,2 butadiene pentadienes

27 Impact of water using silica adsorbent

28 Elution of water from Silica BOND coating Detection by 120 C Abundance TIC: D\ data.ms Water elutes from silica adsorbent Time-->

29 Impact of water 9 splitted injections of water,1 ul, 1:20 pa 100 *FID1 A, Front Signal (SILICA PLOT\012413F D) *FID1 A, Front Signal (SILICA PLOT\012413F D) before after Low water levels have no impact on retention time min

30 Impact of water Effect of 1 ul water, On-column pa 100 *FID1 A, Front Signal (SILICA PLOT\012913F D) *FID1 A, Front Signal (SILICA PLOT\012913F D) Slight difference in selectivity and retention times not quite as bad as the Varian column min

31 Findings Silica can tolerate water much better then alumina Reproducible retention times Usable at lower iso temperatures Large water amounts will affect retention, but impact is very low. A simple conditioning step will remove water as silica has little affinity

32 Sulfur testing And benchmarking

33 Sulfur testing New silica PLOT columns were tested for sulfur response using an Agilent MSD 30m x 0.32mm silica columns were installed in a GC/MS and compared using same injection system and temperatures.

34 New Silica BOND technology Abundance Ion (59.70 to 60.70): D\data.ms Ion (33.70 to 34.70): D\data.ms Ion (42.70 to 43.70): D\data.ms Ion (46.70 to 47.70): D\data.ms H2S Time-->

35 Peak shape of H2S 4.50

36 Comparison of peak shape H2S peak for the 3 columns Agilent silica type 1 Agilent silica type 2 Rt-Silica BOND 4.50

37 Better peak shape means Higher response when analyzing traces Lower detection limits More correct results at trace levels Trace impurities in C2 and C3 streams 4.50

38 Analysis of sulfur contaminants in GPL (Butane or Propane) by Gas Chromatography with PFPD Detector and specific Capillary Column. Project Intertek Marseille, done with Interscience

39 Typical chromatogram of Gas Bottle#1. Sulfur in 100% Propane. Propane elutes between COS and H2S Ref: Interscience /Intertek Marseille

40 Typical chromatogram of Gas Bottle#2. Sulfur in 100% Butane. Butane elutes just before CS2 Ref:Interscience / Intertek Marseille

41 Typical chromatogram customer sample. Commercial Propane. A second hydrocarbon is present. It s probably Pentane because this sample has been injected on RGA Analyser in order to determinate hydrocarbons. Ref:Interscience / Intertek Marseille

42 Sulfur LOD in butane using PFPD LOD Butane Conc Bottle(ppm) Noise(mV) Height(mV) LOD(ppm) H2S COS MeSH EtSH CS propanethiol DMS DMDS Table 8. Sulfur LOD in Propane

43 54 ppb H2S and 64 ppb COS in N2 SClD detection COS 64 ppb H2S 54 ppb SF6 10ppb Ref: Lou d Agostaro, DCG partnership

44 Halogenated compounds Silica is very inert and will also elute volatile halogenated compounds

45 Numbering system CFC Take the numbering and add 90 to it The first numeral gives the nr of Carbon atoms; The second gives the nr of Hydrogen atoms; The Third numeral gives the nr of Fluor atoms; The rest of the carbon bonds have Chlorine atoms; Example: CFC 115 : = Carbon, 0 Hydrogen, 5 Fluor So, there is 1 Chlorine Pentafluoro, (mono)chloroethane

46 CFC separations FID1 A, Front Signal (SILICA PLOT\010913F D) pa CFC12 CFC113a CFC CFC22 CFC11 MeCl2 CFC mi

47 Beta testing fort CFC compounds Retention time [min] Peak Identification R13B1 R290 R32 R218 R115 R125 R143 + R12 R22 R600a R134a R600 R152a R114 R124 R142b R11 R141b Klaas van Dijk laboratory safety advisor transport of dangerous goods (ADR) Crealis Nederland B.V. Van Konijnenburgweg PL Bergen op Zoom The Netherlands

48 Time (min)

49 Summary A new silica based PLOT column has been developed with improved characteristics Stable layer, no particle release Water minimally impacts retention times Better peak shape for sulfurs and halo carbons