Compatibility Assessment of

Isobutanol-Gasoline Fuel

Blends with Fueling

Infrastructure Materials

Mike Kass, Tim Theiss, Chris Janke,

Steve Pawel, and Jeff Thomson Oak Ridge National Laboratory

Jim Baustian and Les Wolf Butamax Advanced Biofuels, LLC

Wolf Koch Technology Resources International, Inc.

24th National Tanks Conference & Expo

Denver, CO

September 17, 2013

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Isobutanol is of interest since it provides a pathway for meeting the 36BGPY RFS requirement by allowing greater biofuel usage than can be achieved by ethanol alone

• Isobutanol can be produced from existing ethanol production plants via retrofit technology

Property Isobutanol Ethanol Gasoline

Oxygen (wt.%) 21.6 34.7 ----

Blending ratio to achieve

3.7 wt.% oxygen, (%) 16 10 ----

Heating Value relative to

Gasoline (%) 84 66 100

Blending octane 105 122 87

Polarity Index 4 5.2 <2.4

Solubility in water (mL/100mL) 8.7 miscible <0.01

• Isobutanol has a much higher energy density than ethanol

• Water has a relatively low solubility with isobutanol

• Isobutanol has a slightly lower polarity index than ethanol suggesting reduced corrosion potential

Isobutanol Ethanol

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• Prior test fuels included Fuel C, CE10a, CE17a, and CE25a, CE50a and CE85a

• Polymer specimens measured for change in volume, mass, hardness and DMA

• Specimens exposed to test fuel liquid and vapor phase regions

• Ethanol compatibility effort funded by DOE

Metals & Alloys Elastomers Plastics

304 stainless steel Fluorocarbons (2) HDPE

1020 carbon steel NBRs (6) Polypropylene

1100 aluminum Silicone rubber POM (2)

Cartridge brass Fluorosilicone Nylon (4)

Phosphor bronze Neoprene PVDF

Nickel 201 SBR PTFE (Teflon)

Terne-plated steel Polyurethane PPS

Galvanized steel Rubberized cork (2) PET (2)

Cr-plated brass PBT

Cr-plated steel PTU

Ni-plated aluminum Isophthalic polyester

resin (2-types)

Ni-plated steel Terephthalic polyester

resin

Novolac vinyl ester

resin

Epoxy resins (2-types

and 2-cures)

Goal: To provide a data set of material properties for use to the fueling infrastructure community

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Emergency Shear ValveProtector (Iron, steel, brass, SS, Teflon, polyurethane)

Vapor Line Shear Valve(Iron, fluorocarbon, polyurethane)

Flexible connector(SS, fluorocarbon, NBR)

Nozzle (nylon, Al, fluorocarbon, Silicone rubber, NBR, fluorosilicone, HDPE)

Flow limiter (Al, steel)

Breakaway valve (nylon, HDPE, fluorocarbon, NBR, fluorosilicone)

Swivel (SS, fluorocarbon, NBR)

Ball float vent valve (steel, SS)

Extractor fitting (iron, polyurethane, Zn alloy)

Pump (steel, aluminum)

Piping (nylon, PVDF, PPS, polyester resins)

Hose (NBR)

Tank Bottom Protector (Al, SS)

Pressure Vacuum Vent(polypropylene, SS, Al)

LIQUID

VAPOR

Jack Screw(see adapter)

Spill container(Al, fluorosilicone, nylon)

Adapter(Bronze, Al, polyurethane,

nylon, SS, NBR)

Overfill protectionvalve (see adapter)

Tanker Truck Pump Line

UndergroundFuel Storage Tank

Fuel Dispenser

Tank walls (Steel, thermosetting plastic resins)

PTFE,

Many of the materials investigated in this study have direct use in fuel storage and delivery systems

Some materials may have been missed

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Ethanol-blend test fuels were formulated based on SAE J1681, which also served as the basis for the isobutanol-blend test fuels

• Ref Fuel C is a test fuel representing gasoline. It is a mix of 50% toluene and 50% isooctane

• An aggressive isobutanol was formulated based on the constituents and molar concentrations of “aggressive ethanol”

• Oxygen equivalency:

– CE10a corresponds to CiBu16a

– CE17a corresponds to CiBu24a

• CE17a was chosen to represent E15

Component Mass

(g)

Reagent grade isobutanol 797.7

De-ionized water 7.987

Sodium chloride 0.004

Sulfuric acid 0.021

Isobutyric acid 0.088

Material Type Test Fuel Formulation

Fuel C CE10a CE17a CE25a CiBu16a CiBu24a

Elastomers X X X X X X

Metals X X X X X X

Plastics X X X X

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Presented results highlight the volume and hardness change (from the original baseline condition) and the glass-to-rubber transition temperature for the elastomer and plastic materials

Wetted Property Measurement Indicates:

– Extent of solubility

– Extrusion potential (elastomers)

– Extent of softening

– Potential residual stress (plastics)

Dried Property Measurement Indicates:

– Dissolution (removal of one or more

components)

– Embrittlement (removal of plasticizer

components)

– Fluid retention

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Elastomer Types and Applications

Materials

• Fluorocarbon (2 types)

• Fluorosilicone

• NBRs (6-types)

• Neoprene

• Polyurethane

• SBR

• Silicone

High performance seals

(o-rings, gaskets, etc.)

Seals (o-rings, gaskets, etc.)

Hoses (all applications)

Seals (gaskets, etc.)

Applications

Coatings

Seals (gaskets, etc.)

?

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Volume Swell Results for Elastomers:

• Fluoroelastomers swelled the least; while SBR and silicone swelled the highest

• The addition of ethanol or isobutanol was observed to increase swell, and in most cases, isobutanol produced slightly lower swelling than equivalent levels of ethanol

NBRs swelled15-25% with

Fuel C and an additional 10%

with the oxygenated test fuels

Isobutanol had no added

effect for SBR and silicone.

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Wet Hardness Results for Elastomers: The swelling was accompanied by a reduction in hardness (softening). In general, the extent of softening corresponded to the level of swell.

Polyurethane was softened

by ethanol and isobutanol

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Dried Volume Results for Elastomers: After drying for 20h at 60oC, shrinkage was observed for the NBRs, neoprene, SBR, and polyurethane (shrinkage is indicative of extraction)

• Fluorocarbons maintained a small level of expansion

• Shrinkage observed for NBRs, neoprene, and SBR was primarily caused by Fuel C

• Polyurethane was the elastomer most affected by the alcohol components (especially ethanol)

• Fluorosilicone and silicone returned to their starting geometries

Key Observations:

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Dried Hardness Results for Elastomers: The change in hardness results after drying showed that the hardness was increased (embrittled) for the NBRs and neoprene

• Fluorocarbons remained softened

• Fluorosilicone and silicone returned to their starting values

• Polyurethane remained softened by the alcohols

• In general the added isobutanol performed similar to ethanol

• SBR showed more sensitivity to isobutanol than ethanol

Key Observations:

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Glass to rubber transition temperature results for the elastomers showed small changes from original unexposed baseline condition

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Plastic Types and Applications

Materials

• PPS

• PET (Mylar)

• PTFE (Teflon)

• PVDF

• Nylon 12

• Nylon 6

• Nylon 6,6

• Nylon 11 (vegetable oil derived)

• HDPE

• Vinyl ester resin

• Terephthalic polyester resin

Permeation barriers for

plastic piping

Applications

Structural support and

outer walls of flexible

plastic piping

Resins for fiberglass

tanks and piping

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Volume Swell Results for Plastics:

• Terephthalic polyester resin exhibited 7% swelling with Fuel C and ~25%with exposure to the oxygenated fuel compositions

• Compared to terephthalic polyester, the vinyl ester resin exhibited better compatibility to the test fuels, except for CE25a

• Barrier materials exhibited the lowest level of swell

• The results for the nylons varied according to type. Nylon 12 expanded 7-10% with exposure to the oxygenated fuels. Nylon 6 and Nylon 6,6 exhibited only slight swell with the isobutanol test fuels

Nylon 11 swelled 5% with

Fuel C and 18% with CE25a

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Wet Hardness Results for Plastics:

For many plastics, the hardness results did not change much. The most affected were Nylon 11 and terephthalic polyester

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Dried Volume Results for Plastics: When dried many of the plastics exhibited volume expansion (compared to baseline) • Barrier materials and HDPE returned to their original volumes

• Nylons 6 and 6,6 were not affected by Fuel C and isobutanol, but they did show expansion with CE25a

• After drying, the resins remained swollen following exposure to CE25a, CiBu16a and CiBu24a

• Of the two resins studied, the vinyl ester resin exhibited better compatibility to the test fuels, except for CE25a

Nylon 12 experienced

shrinkage

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Dried Hardness Results for Plastics: Observed softening corresponds to the level of retained fuel (or volume increase)

Deviation from

baseline is low

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Glass Transition Temperature Results for Plastics: These results indicate that some structural change had occurred for PET, nylon, and resins with exposure to one or more of the test fuels

PET showed no accompanying

changes in volume and hardness

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Summary of Key Findings

• Of the two classes of polymers studies, elastomers usually exhibited higher levels of swelling than plastics

– Much of this volume expansion can be attributed to Fuel C, however, the NBRs and neoprene showed additional expansion with the fuels containing ethanol or isobutanol

• In general, after drying, the elastomers experienced some level of shrinkage.

– The NBRs and neoprene exhibited a measureable hardness increase (embrittlement) indicating that the plascticer components may have been extracted by the test fuels.

– The fluorosilicone and silicone specimens returned to their original volumes

– Polyurethane was structurally degraded

• The plastics exhibited a wide range of swelling

– The permeation barriers swelled the least

– The results for the nylons varied according to type

– The resins swelled over 20% with CE25a

• After drying the plastics remained swollen (except for Nylon 12 which lost volume)

– The resins had exhibited higher volume expansion with exposure to the oxygenated test fuels

• In general the addition of ethanol and isobutanol produced similar results. In most cases the level of swell and softening was less with isobutanol compared to oxygen equivalent levels of ethanol.

• Structural changes may exist even if the hardness and volume are not affected

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Thank You for Your Attention!

• Further information can be found in the following report:

Compatibility Study for Plastic, Elastomeric, and Metallic Fueling

Infrastructure Materials Exposed to Aggressive Formulations of Isobutanol-

blended Gasoline

http://info.ornl.gov/sites/publications/Files/Pub44488.pdf

www.osti.gov/servlets/purl/1092302/

• Future work is being planned. If there is a material that you think should be

included, please let us know and we’ll add it to the matrix