Analysis and Chromatographic Separation of Oxygenates · PDF fileAnalysis and Chromatographic Separation of Oxygenates in Hydrocarbon Matrices Simon Jones Application Engineer Folsom,

Analysis and ChromatographicChromatographic

Separation of Oxygenates in yg

Hydrocarbon MatricesSimon JonesApplication EngineerFolsom, CAA t 20 2009August 20, 2009

GS-OxyPLOT Agilent Restricted

Pittcon 2007, Chicago, IL

Agenda

WCOT vs. PLOT columns

OxyPlot A Unique stationary phaseOxyPlot – A Unique stationary phaseTrace oxygenates in reformulated gasoline

Capillary Flow Technology (CFT)Capillary Flow Technology (CFT)Heart cutting and back-flushing



WCOT vs. PLOT

Type Stationary ChromatographicP

Stationary Type Phase Process Phases

WCOT Liquid orgum

Gas / Liquidpartition

PolysiloxanesPEG

PLOT Solid Gas solid Porous Polymers,So dadsorption

o ous o y e s,Al2O3,

Zeolites, etc.



Film Thickness and Retention (WCOT): Isothermal

Thickness (µm) Retention Change0.10 0.400.25 1.001.0 4.003.0 12.05.0 20.0

Constant DiameterN li d t 0 25



Normalized to 0.25 µm

Film Thickness and Resolution

Wh l t k 5 Rdf

When solute k < 5

or T(early eluters)

or T

RWhen solute k > 5 df

or T(later eluters)



WCOT Ethylene Analysis



PLOT Ethylene Analysis



Capillary Column Types

P L O T b (PLOT)

Carrier Gas

Porous Layer Open Tube (PLOT)

Solid ParticlesCarrier Gas

W ll C t d O T b (WCOT)Wall Coated Open Tube (WCOT)

Liquid PhaseCarrier Gas



PLOT Columns

"Solid"PorousPorousLayer

F d SiliFused Silica Tubing

Ideal for the anal sis of gases d e toIdeal for the analysis of gases due totheir increased retention (k) and uniqueselectivity (α) compared to WCOT



selectivity (α) compared to WCOT

Selectivity Interactions in PLOT Phases

Shape / Size SurfaceZeolites Al2O3

Porous Polymers

Bonded Carbon Bonded SilicaMolecular Sieves



Surface Interactions in PLOT Columns

+ + + + + + + + + + + + +

Gas Flow δ- δ- δ+δ+

neutral

+ + + + + + + + + + + + +

Vapor pressure always plays a leading role in solute interactions



Vapor pressure always plays a leading role in solute interactions

Considerations for PLOT Column AnalysisColumn Analysis

• Inlet issues• split versus direct injection• gas sampling valves• low dead volume• column ID and flow rate

• Detector issues• particle generation or “spiking”; particle traps• column ID and flow rate



Considerations for PLOT Column AnalysisColumn Analysis

• Column issues• selectivity• capacity; overloaded peaks• inertness• temperature limits• Elution order of major peak

• Column contamination • efficiency loss; “ghost peaks”; increase in bleed

water CO high molecular weight hydrocarbons?• water, CO2, high molecular weight hydrocarbons?• Carrier gas purifiers



J&W / Agilent PLOT Columns

•GS-OxyPlot

GS Alumina

• HP-PLOT MoleSieve

• GS CarbonPLOT•GS-Alumina

• HP-PLOT Al2O3 “M”

• GS-CarbonPLOT

• HP-PLOT Q

• HP-PLOT Al2O3 “S”

• HP-PLOT Al2O3 “KCl

• HP-PLOT U

• GS-GasPro



Application SummaryPetrochemical and Chemical companies have a need toPetrochemical and Chemical companies have a need to quantitatively measure low level oxygenates in petroleum products

Gas

Oil FieldsShipping Ctrs

Distribution CentersCrude Oil

Light HCsGasJet FuelDieselRefineries

Fuel Oil

Shipping Ctrs DieselFuel Oil

Diesel



Application SummaryPetrochemical and Chemical companies have a need toPetrochemical and Chemical companies have a need to quantitatively measure low level oxygenates in petroleum products

G

Oil FieldsDistribution

C tCrude Oil

Light HCsGas

Gas

Fuel Oil FieldsShipping Ctrs

CentersOilJet FuelDieselFuel Oil

Refineries Oil

Diesel

The need to measure trace oxygenates from 10to 1000 ppm in Gasoline

• Problems with MTBE in reformulated gasoline• MTBE causing groundwater contamination• Desire to use ethanol as a renewable, green fuel additive



Oxygenates in Gasoline and NaphthaWhy is this measurement neededy• Oxygenated additives in reformulated gasoline

– Needed for clean air regulations and petroleum fuel extenders• Problems with groundwater contamination

– Ethers in gasoline (MTBE, ETBE, TAME) in underground tanks– Greater toxicity than alcohol additives

– Move toward biofuels– Fuels derived from renewable agricultural products– Ethanol from fermentation of biomass– Lower toxicity than other alcohols

• Improve quality of feedstocks– Gasoline and naphtha used as feedstock for other HPI productsp p– Traces of oxygenates poison catalyst

• lower production yields• lower product quality



lower product quality

Traditional Oxygenates Methods

ASTM D4815• Valve based using TCEP packed/ DB 1 capillary column• Valve based using TCEP packed/ DB-1 capillary column• Used to measure oxygenated additives (0.1 wt% to 15 wt%)• ASTM study shows that D4815 has interference problems

– TCEP column cannot separate trace oxygenates from trace olefins

ASTM D5599ASTM D5599• Single column method using oxygen selective detector (OFID)• Expensive system that is dedicated to only one application• Expensive system that is dedicated to only one application• Selectivity and sensitivity may not be good enough for low ppm



New Method Under Development by ASTM D2Method ScopeMethod Scope

• Trace oxygenates in finished gasoline from 10 ppm to 1000 ppm (wt/wt)• Oxygenates include:

– methanol, n-propanol, i-propanol, n-butanol, s-butanol, t-butanol, s-butanol, t-pentanol

– MTBE, ETBE, DIPE, TAME– Ethanol additive from 1 to 15 wt%– Internal standard: 1,2-dimethoxyethane (DME)

Other capabilitiesOther capabilities

• can measure other oxygenate contaminants– ketones and other alcohols and ethers

• can be used for naphthas• sensitivity range can be lowered to 1 ppm with no changes in method conditions



New Proposed ASTM Method Instrumentation ConfigurationConfiguration

• Uses valve switching 2-D GC

• DB-1 column separates oxygenates/light hydrocarbons from heavy hydrocarbons

• New Agilent GS-OxyPLOT column separates light g y p ghydrocarbons from oxygenates



Proposed ASTM Methods Uses 2-D GC with Oxygenate Selective PLOT ColumnOxygenate Selective PLOT Column

FIDS/SLFlowSource

DB-1

Vent

OxyPLOT1

2

3

4

5

61. Sample introduction of gasoline onto DB-1 pre-column GS-

30m x 0.53mmid x 5um

AuxEPC

10m x 0.53mmidof gasoline onto DB-1 pre-column.

FIDS/SLFlowSource

DB-130m x 0.53mmid x 5um

Vent

OxyPLOT10m x 0.53mmid

1

2

3

4

5

6

2. Oxygenates and light hydrocarbons transfer to GS-OxyPlot. Heavy hydrocarbons remain on DB-1 pre-

lGS-

AuxEPC

Vent

column.

FIDS/SLFlowSource

DB-130m x 0.53mmid x 5um

OxyPLOT10m x 0.53mmid

1

2

3

4

5

6

3. Heavy hydrocarbons vented from DB-1 pre-column. Oxygenates resolved on GS-OxyPlot column.

GS-



AuxEPC

What Is GS-OxyPLOT?A 10 0 53 I D 10 fil thi k P L O• A 10 m x 0.53 mm I.D., 10 µm film thickness, Porous Layer Open Tubular (PLOT) Capillary Column. New Agilent p/n 115-4912.

• The stationary phase is a “proprietary, salt deactivated adsorbent”.K h t i ti• Key characteristics are:– Strong selectivity to oxygenated hydrocarbons.– Methanol (BP 65 °C) elutes after Tetradecane (BP 254°C)

Solute MTBE Iso-Butylaldehyde

Methanol Acetone

RI* 1236 1368 1418 1450RI* 1236 1368 1418 1450

– Upper temperature limit 350°C with no column bleed

*150°C

pp p– Stabilized phase coating, minimizing particle generation and

detector spiking



GS-Oxy-PLOT “Electronic” Selective Interactions

Distinct Advantages• Adsorption interactions are much stronger than the polar/non-polar

interactions in “liquid” stationary phasesinteractions in liquid stationary phases. – Oxygenated hydrocarbons, un-retained in a WCOT column even at

sub-ambient temperatures can exhibit high retention in a PLOT column at GC oven temperatures above ambientcolumn at GC oven temperatures above ambient

– Non-polar solutes are essentially un-retained except for their vapor pressure interaction at a given oven temperature.

– Ideal column for selective solute-value cut applications

• Column phase is surprisingly inert to the polar compounds it so stronglyColumn phase is surprisingly inert to the polar compounds it so strongly interacts with.– Good for low concentration, quantitative GC analysis



OxyPlot Column Separation of Trace Oxygenates and Ethanol Additive in Reformulated Gasolineand Ethanol Additive in Reformulated Gasoline

Light HydrocarbonsEthanolEthanol

EthersMethanol

C3 to C5 Alcohols

5 10 15 20 25 min.

Methanol

BE

E nol

ETB

EM

TBD

IPE TA

ME

OH

Pro

pano

l

t,s,i-

But

a n

But

anol

-Pen

tano

l

E(IS

)

E D

MeO

i,n-P n-B t-

1,2-

DM

E



min12.5 13.5 14.5 15.5 min22 23 24 25 26 27

Ethanol Influenced Retention Time Shifts

12 wt% ethanol

1 wt% ethanol

12 14 16 18 20 22 24 min.

ETBE12.498

MTBE12.660 DIPE

12.789

TAME13.755

MeOH15.463

12.753 13.852

min12 12 5 13 13 5 14 14 5 15 15 5

12.601 12.886 15.687



min12 12.5 13 13.5 14 14.5 15 15.5

Excellent Quantitative Precision

Expected Avg Std Dev RSD(ppm)* (ppm)* (ppm)*

High Concentration QA/QC Check SampleExpected Avg Std Dev RSD

(ppm)* (ppm)* (ppm)*

Low Concentration QA/QC Check Sample

(pp ) (pp ) (pp )ETBE 780 758 1.3 0.2%MTBE 795 816 1.5 0.2%DIPE 795 758 1.1 0.2%TAME 779 779 1.4 0.2%

(pp ) (pp ) (pp )ETBE 49 48 0.7 1.4%MTBE 49 46 1.0 2.1%DIPE 49 93 0.7 0.8%TAME 48 48 0.3 0.6%

Methanol 802 759 1.6 0.2%Ethanol* 12.0% 11.3% 0.0 0.4%i,n-Propanol 1619 1566 14.7 0.9%t,s,i-Butanol 2399 2372 4.4 0.2%n-Butanol 798 791 1 7 0 2%

Methanol 50 67 0.6 0.8%Ethanol* 1.0% 0.9% 0.0 2.2%i,n-Propanol 101 95 1.3 1.4%t,s,i-Butanol 150 152 2.4 1.6%n-Butanol 50 47 0 8 1 6%

*ethanol results are in wt%

n-Butanol 798 791 1.7 0.2%t-Pentanol 801 766 0.6 0.1%

n-Butanol 50 47 0.8 1.6%t-Pentanol 50 47 0.2 0.5%

Each QA/QC sample prepared in reformulated gasolineEach QA/QC sample prepared in reformulated gasolineFive consecutive runs of each sample



New Method Under Development by ASTM D2 for Analysis of Oxygenates in Ethene, Propene, C4Analysis of Oxygenates in Ethene, Propene, C4 and C5 Hydrocarbon Matrices

Method ScopeMethod Scope

•Oxygenates in these light hydrocarbon matrices from 500 ppb to 100 ppm (wt/wt)•Oxygenates include 25 alcohols, ketones, aldehydes and ethers (e.g.):

–methanol, ethanol, n-propanol, n-butanol, s-butanol, t-butanol, s-butanol–DME, MTBE, DIPE, TAME–Acetone, acetaldehyde Liquid

SampleGas

Sample

Similar in principle to Fused Silica

Restrictor

1 mL

2 µLp pthe oxygenates in gasoline method DB-1

25 m X 0.53mm I.D., 1.0 µm GS-OxyPLOT

10 m X 0.53mm I.D., 10 µm

2 µL



Hydrocarbons and Oxygenates Separation Using DB-1 Stripper Column and GS-OxyPLOT Separation Column

Isooctane

Benzene

1. Dimethyl ether

2. Diethyl ether

3. Acetaldehyde

4. Ethyl t-butyl ether

13. Acetone14. Isovaleraldehyde15. Valeraldehyde16. MEK17 Ethanol

Column 1: DB1, 25 m x 0.53 mm x 1 um

P/N 125-102J

Column 2: GS-Oxy-PLOT, 10 m x 0.53 mmP/N 115-4912

Carrier gas: Helium, 40 cm/s @ 50°C

8 5. Methyl t-butyl ether

6. Diisopropyl ether

7. Propionaldehyde

8. Tert-amyl methyl ether

9 P l th

17. Ethanol18. 1-Propanol19. Isopropyl Alcohol20. Allyl Alcohol21. Isobutyl Alcohol

Carrier gas: Helium, 40 cm/s @ 50 CInjection volume: 1 uLInlet: Split, 250

• Temperature: 225 oC• Split Ratio: 10:1• Column flow: 11 mL/min

n-Octane

2

3

4

5 6

9

21,22,23

9. Propyl ether

10. Isobutylaldehyde

11. Butylaldehyde

12. Methanol

22. t-Butyl Alcohol23. s-Butyl Alcohol24. n-Butyl Alcohol25. 2-Methyl-2-pentanol

3

7

10

11

12

13

14

15

1819

2017Backflush occurs here

Oven

• Initial temp 50 oC• Initial hold 5 min• Ramp rate: 10 oC/min• Final temp 240 oC

1

11 13 15

16 24 25

Final temp 240 C



SummaryA New Proposed ASTM Method for Trace Oxygenates inA New Proposed ASTM Method for Trace Oxygenates in Reformulated Gasoline• designed to measure 10 to 1000 ppm oxygenates in gasoline with 1 to 15

wt% ethanol additive

Agilent 7890A GC System with GS-OxyPlot Column meets method requirementsmethod requirements• excellent separation of oxygenates from light hydrocarbons• resolves all ethers (ETBE, MTBE, DIPE, and TAME)• high quantitative precision for both high and low concentrations in the

presence of percent ethanol

A New Proposed ASTM Method for Trace Oxygenates in LightA New Proposed ASTM Method for Trace Oxygenates in Light Hydrocarbon Matrices• designed to measure 500 ppb to 100 ppm oxygenates in matrices with



g pp pp ygBPts less than 200°C

Old vs. New Switching Technology

Previous Slides depicted “Old-school” method of switching column flow

Newer method uses Capillary Flow Technology (CFT)No moving partsNo moving partsLow dead volumeLow thermal mass



Challenges For Inside the Oven Devices

– Inertness (it is in the sample path)L d d l (i i i h i h)– Low dead volume (it is in the separation path)

– Leak free (especially with repeated temp cycling)– Fast thermal response (follow rapid oven ramping)– High temp tolerance (GC oven can go over 350C)– Reliable and easy to use



Types of Connectors Used In The GC OvenLi it ti

Metal Packed columns, Not inert, no ferrule

Advantages Limitations

Fittings reliable for capillary columns

Press Fit Glass

Low dead volume, inert, low cost

Difficult to assemble, comes apart

Graphite High temperature Sheds active graphite particles into sample path

Polyimide Low initial leakage

path

Loosens and leaks with oven cycling,



y gsolvent tailing

IF We Only Had A Technology That Provided Easy, Reliable Flow Structures In The GC Oven...Reliable Flow Structures In The GC Oven...It would open up many new (and old) capabilities for GC

– Column connections (connect pre-column)– Column connections (connect pre-column) – Change MSD columns (without venting) – Backflush (Reverse flow through column)– Detector splitter (effluent split to two or more detectors)– Merge flows (2 columns to 1 MSD)

Deans switch (heart cut select peaks to 2nd column)– Deans switch (heart cut select peaks to 2nd column)– Comprehensive 2-D GC (cut all peaks to 2nd column) – etc.



5 Key Developments in Capillary Flow Technology

Easy to use, do not loosen or leak with oven cycling to 400°C

Metal Ferrules

Complex flow structures with low thermal massManifold Plates

Makes metal surfaces as inert as columnDeactivation of Metal

Backflushing now possible, change MSD columns without venting, known column outlet pressure

EPCpressure

Accurately predict flows and pressures BEFORE installing devicesCalculators



BEFORE installing devices

Capillary Flow Technology- Design a proprietary Agilent Technology

• Photolithographic chemical milling for low dead volume

… a proprietary Agilent Technology

g p g

• Diffusion bond two halves to form a single flow plate

• Small, thin profile provides fast thermal response

• Projection welded connections for leak tight fittings

• Deactivation of all internal surfaces for inertness



The Metal FerruleDoes not loosen (leak) even with thousands of runs to 350C

Seal region

Does not loosen (leak) even with thousands of runs to 350CDoes not shed particles

Square cut is



not critical

Capillary Flow Technology

Column 1 In

Restrictor 1

out to vent

Restrictor 2

or Column 2out to vent

Nut

or Column 2

Ferrule

Channel

Plate



Plate

Comparison of New Fitting with Polyimide Fitting

PolyimidePolyimide Fitting

Exposure to polyimide and unpurged annular spaces is greatly reduced

New Fitting

Ferrule Ejector Hole



Ferrule Ejector Hole

Pentane test chromatogramFitting Design Minimizes Tailing

6

PolyimideFID direct

4

5

FID directCapillary Flow fitting

2

3

0

1

Capillary Flow Technology fittings avoid tailing with ll b t ll t d d l

1.1 1.15 1.2 1.25 1.3

0



small but well swept dead volume

Capillary Flow Technology- Capabilities

Solvent Bypass

Heart Cutting (Deans Switch)

D S li i

Backflush

Detector Splitting

QuickSwapQuickSwap

Modulation (GCXGC)



Modulation (GCXGC)

Dean SwitchHeartcutting 2-D GC provides extremely high

Cut

Heartcutting 2-D GC provides extremely high chromatographic resolution

Auto-sampler

Deans Switch

FID1 FID2

Switch

Column 1 Column 2

7890A GC

Column 1 Column 2



2-D Separation of Sulfur Compound in Diesel FuelCompound is completely resolved and can be analyzed

Heart Cut to Column 2

Compound is completely resolved and can be analyzed with FID

Heart Cut to Column 2

Column 1 - FID 1

Diesel Fuel

Trace Sulfur Compound(4,6-DMDBT)

C l 2 FID 2Hydrocarbon

MatrixColumn 2 – FID 2 Matrix



0 2 4 6 8 10 12 14 16 18 min.

QuickSwapChange MSD columns without ventingChange MSD columns without ventingBackflush heavy components out split vent

MSD TransferlineAuto-sampler

AUX EPC4 psig

171 mm X 0 121 mm id

Column

0.121 mm id restrictor

7890A GC

5975C InertMSD



QuickSwap MSD Interface

Remove column w/o venting– Air & H2O blocked2

Safe disconnection of column from inlet for inlet maintenance

Column Effluent

– Reversed flow through column during inlet maintenance

BackflushingMSD TransferLiBackflushing

– Removes heavies from column

Maintain constant flow to MSD

Line

Maintain constant flow to MSD

Aux EPC In



(flow rates exceeding 2 mL/min require an MSD with Performance Turbo)

Thank you!y

Questions?

Feel free to contact Agilent Application Support at:

1-800-227-9770 Option 3.3.1….or…..

via e-mail at:

[email protected]



Analysis and Chromatographic Separation of Oxygenates · PDF fileAnalysis and Chromatographic Separation of Oxygenates in Hydrocarbon Matrices Simon Jones Application Engineer Folsom,

Documents