the importance of biodiesel stability

BIODIESEL EXPOSICION TECNICA

Rosario, Argentina, July 11th, 2007

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The Importance of Biodiesel The Importance of Biodiesel Oxidation StabilityOxidation Stability

by Phil BuremanSenior Regional Account ManagerNalco CompanyOlathe, Kansas USA

[email protected]



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Where Is Olathe, Kansas, USA?Where Is Olathe, Kansas, USA?

The Cowboy Boot was invented in Olathe!



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Agenda

• Why is biodiesel oxidatively unstable?

• Why is oxidation stability important in biodiesel?

• What can be done mechanically, operationally and chemically to improve oxidation stability?



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Instability Is Instability Is Also A GoodAlso A Good Thing! Thing!

Why is biodiesel unstable?

Why is stability important?

Managing biodiesel stability

Malbec Grapes

• Biodiesel is derived from natural vegetable or animal feedstocks• Biodiesel is made up of various methyl esters

- All of which break down over time• Biodiesel is “biodegradable”

- This is a good thing for the environment! - But this instability can also result in operational problems in fuels



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Transesterification of Triglycerides




The type of fatty acid (R, R’, R’’) making up the triglyceride will vary with the feedstock

R’-CH2

R-CH

R’’-CH2

CH3-OH

CH2-OH

CH-OH

CH2-OH

Triglyceride (soy oil)

Methanol

+Catalyst

Mixed Methyl Esters (FAME or Biodiesel)

+

Glycerin

O

R-O-CH3

O

R’-O-CH3 O

R’’-O-CH3



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Different Feed Stocks Contain Different of Triglycerides




Stearic Fatty Acid

Palmitic Fatty Acid CH2

Oleic Fatty Acid CH2

CH

Stearic Fatty Acid


Linoleic Fatty Acid CH2

CH

Linoleic Fatty Acid

Linoleic Fatty Acid CH2

Oleic Fatty Acid CH2

CHPalmitic Fatty Acid


Stearic Fatty Acid CH2

CH

The type of fatty acids in the feedstock affects the stability of the biodiesel



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Methyl Ester Make Up Determines Stability

Why biodiesel Is unstable?



Methyl Ester Name

# of Carbons

# of Unsaturated Bonds

Relative Oxidation Stability

Palmitate 16 Zero High

Stearate 18 Zero High

Palmitoleate 16 1 Medium

Oleate 18 1 Medium

Linoleate 18 2 Low

Linolenate 18 3 Low



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Feedstock Choice




• Biodiesel feedstock will vary in degree of Hydrogen Saturation (or the number of double bonds)

• The # of carbon atoms and double bonds affect: – The natural oxidation stability of the biodiesel– And the response to anti-oxidants



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Biodiesel Stability




0

2

4

6

8

10

ULSD X Y Z

B100 Source

Ind

uc

tio

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ime

, h

ou

rsUntreated + 100 ppm Nalco Anti-Oxidant

European Spec

USA Spec



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Unsaturated Bonds Instability

• Oxidative instability begins with an initial chain reaction: RH → R•

• Followed by a propagating reaction that involves unstable peroxides and hydro-peroxides:R• + O2 → RO2•ROO• + RH → R-OOH + R•

• Followed by the termination reactions resulting in aldehydes, alcohols and carbonic acids:R• + R• → R-RROO• + R• → R-OO-R

• The reaction products also will polymerize and form sludge, sediment, varnish & lacquer




KEY POINT: Oxidation catalyzes KEY POINT: Oxidation catalyzes moremore oxidation! oxidation!



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Instability Creates More Instability

The Cycle of Radical Induced Oxidation

KEY POINT: Oxidation catalyzes KEY POINT: Oxidation catalyzes moremore oxidation! oxidation!






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Other Factors

• Biodiesel contains natural anti-oxidants such as tocopherols– Tallow and palm oils tend to be more

naturally stable than soy oil• Excess water will decrease oxidation

stability– Water can be entrained in biodiesel by:

• Free fatty acids (FFA)• Soaps formed by FFA & excess caustic• Free glycerin and MAG, DAG & TAG

• Air entrainment will decrease oxidation stability






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Other FactorsSterol Glucosides

• SG’s occur naturally in vegetable oils and animal fats but are initially soluble– During the biodiesel manufacturing

process, SG’s become insoluble (acylated to non-acylated form)

• As little as 30 ppm of SG’s can result in filter plugging complaints, – SG problems are sometimes mistaken for

stability problems: Both plug filters– Anti-oxidants will not remove SG’s or

prevent filter plugging by SG’s






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Other FactorsSterol Glucosides

• See technical paper: “The Role of Sterol Glucosides on Filter Plugging”, – by ADM’s Inmok Lee, Lisa M.

Pfalzgraf, George B. Poppe, Erica Powers and Troy Haines, Biodiesel Magazine, April 2007

– http://www.biodieselmagazine.com/article.jsp?article_id=1566

• Use Google: SG+ADM+Biodiesel+Magazine– Currently, SG’s can only be removed via

filtration through diatomaceous earth. See the paper above for more information.






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Other Factors

• Petro diesel fuel solvency– Hydrotreating to remove sulfur makes

petro diesel a poorer solvent for sludges sediments varnishes and laquers

– What remained soluble before, may not be soluble in the future!

• Sunlight: Do not store biodiesel in anything that light can penetrate such as polyethylene plastic totes




But why all this concern over stability?But why all this concern over stability?



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It’s All About Customer Satisfaction!

• Biodiesel oxidation results in: – Sludges, sediments and laquers that:

• Change fuel color from light to dark• Clog fuel filters and injectors • Collect in tank bottoms• Lead to other problems such as corrosion

– Unplanned down time– Excess maintenence cost






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It’s All About Customer Satisfaction!




Instability Product

Cost to Equipment Cost to Customer

Insoluble Polymers: sludge & sediment

-Filter Plugging-Deposits on injector and in fuel system-Seizure of moving parts

-Stalling, No Start-Increased smoke-Decreased Fuel Economy

Soluble Polymers - Lacquer formation inside injector cylinder

-Stalling, No Start-Increased cost

Acids -Corrosion of metal parts-Soap formation with metal ions

-Unnecessary costs-Stalling, No Start

Peroxides Embrittlement of elastomers -Fuel leaks-Unplanned downtime

Paraphrased from Robert Bosch Corp. comments @ California Energy Commission, Bioenergy Action Plan Workshop, March 9, 2006

http://www.energy.ca.gov/bioenergy_action_plan/documents/2006-03-09_workshop/2006-03-09_ROBERT_BOSCH.PDF



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• Biodiesel instability can also affect the engine oil – Biodiesel has higher viscosity, density

& surface tension more “fuel blow by”– Resulting in dilution of the lubricant by

the fuel:• More sludge in lubricant; More friction• Increased costs!

– See Lubes & Greases Magazine, June 2007

• www.LNGPublishing.com




It’s All About Customer Satisfaction



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It’s All About Customer Satisfaction




So how do we manage fuel stability?So how do we manage fuel stability?

• The fuel business is a high volume, low margin business!

• Fuel quality must be right ALL THE TIME!– Never give the customer a reason to

blame your fuel for a problem– Even minor equipment failure can lead

to large liability for the fuel supplier• Tow charges, lost wages, demurrage

– Fuel customers have long memories



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• Many soy based biodiesels have high stability initially, i.e. 5+hrs Rancimat– Do not be fooled– This good stability rating can drop

significantly in a short period of time– Plugged fuel filters are the most common

all season biodiesel complaint in the USA• There are several mechanical and

operational issues that can affect biodiesel oxidation stability




1st, Recognize Stability is an Issue with all Biodiesel Fuels



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• You must manage fuel stability:

Mechanically,

Operationally and

Chemically




1st, Recognize Stability is an Issue with all Biodiesel Fuels



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Mechanical Solutions

• Add N2 blanketing capability to storage tanks and rail cars– Expensive “up front” but offers good “ROI”

• Design process and storage tanks and loading systems with bottom fill – Minimize air entrainment

• Never expose biodiesel to copper, zinc or any yellow metal alloys– These metals act as oxidation catalyst– Double check the metal used in your steam

coils– Remove all galvanized pipe and fittings






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• Paint storage tanks white to reduce temperature– Always block any sunlight exposure

• Install water sumps on all storage tanks– Regularly check for and remove water and

check for biological growth• Install desicant breathers to reduce

condensation in storage tanks• Drain, clean and inspect storage tanks

at least every 5 years– SG’s are known to collect in storage tank

bottoms, especially after cool weather






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• Choose biodiesel resistant elastomersWhy biodiesel Is unstable?





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• Buy new storage tanks or clean used tanks very thoroughly before use– Biodiesel will quickly remove old petro

diesel sludges, sediments, laquers & varnish and put that “gunk” in your fuel

• And into your customers fuel filter!• Pro-actively warn customers about this




Let me show you an exampleLet me show you an example



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Biodiesel will clean petro diesel “gunk” from used fuel systemsBiodiesel will clean petro diesel “gunk” from used fuel systemsFuel filters from Dodge pickup truck with ~ 32,000 km, burning it’s first B33 w ULSD

From km 320 to km 640

NewFrom km 130 to

km 320

From km 1 to km 130

What else can you do?What else can you do?

(Photo courtesy of Tri-City Energy Biodiesel)



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Operational Solutions

• Give your self some room for error!• Stability, as measured by the Rancimat

test, has significant test error:– Repeatability +/- 5 %– Reproducibility +/- 11%– Recommend discarding used sample reaction tube

glassware after each test

• Rancimat stability can quickly decrease: – 20-40% in 2-3 weeks of air and light exposure at room

temperature– 10-20% in a open bottle on a lab bench in just 2 weeks






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Operational Solutions

• Minimize water contamination– Maintain low FFA, glycerin, and soap

• Consider a “bio-filter” to remove SG’s– Check for SG’s via the “filter blocking tendency test”

(FBT)—ASTM Method D 2068• If you install vacuum distillation or cation

exchange drying resin– Remember these systems will remove natural anti-

oxidants– These systems can solve other major issues so they

still may be good choices• But they will reduce biodiesel stability!




What about anti-oxidant?What about anti-oxidant?



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Chemical Solutions

• Many good anti-oxidants are available• Some anti-oxidants may be effective

but may cause color changes:– A big issue in the USA and Canada

• Red dye is used to denote sulfur and tax status

• Performance is influenced by the feed stock chemistry (tallow vs soy)– What works well in soy may not

work well in beef tallow or sunflower






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Chemical Solutions

• “Best practice” is to add small amount of oxidation inhibitor every day– Even when initial stability is above

required minimum– This is critical if storage tanks have no N2

blanketing • Apply anti-oxidants as early as

possible to new biodiesel– Anti-oxidants will not remove existing

oxidation damage– Effectiveness is always better in new fuel






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Chemical Solutions

• When choosing an oxidation inhibitor check for:– Fuel additive registration requirements

in the country where the biodiesel will be used

• Most countries restrict usage of fuel additive chemistries or require prior additive/fuel registration– USA requires all CHONS components– Canadian DSL list can be challenging






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Chemical Solutions

• Some anti-oxidants have cold flow or crystalization concerns– Even as high as 10o C.

• Flammability may be a concern• Good mixing is always desired

– Inject upstream of a biodiesel pump• Anti-oxidant treat rate control is vital!

– Too low, results in poor stability• Customer complaints• Producer liability

– Too high, results in excessive costs– Ask your inhibitor supplier to help






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Chemical Solutions

• Regularly monitor and report oxidation stability– Analyze trends– Indentify & solve root cause of deviation– Recognize potential need to change treat

rate target • Change in feedstock (soy to soy/tallow blend)

• Regularly monitor and report oxidation inhibitor usage vs target – Analyze trends– Indentify & solve root cause of devation






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Chemical Solutions

• Make oxidation stability a priority!Why biodiesel Is unstable?



Biodiesel Additive Personal Service ReportCustomer: Big Biodiesel By P BuremanLocation: Soy, IA Date 2/15/2007

Key Manufacturing ParametersMax 4.50 60 405 0.50 0.020% 0.240%Min 1.50 30 135 0.10 0.010% 0.200%Average 2.50 45 225 0.28 0.010% 0.202%

Limits 3 Report 360 0.5 0.020% 0.240%Test Method EN 14112 D2500 D6217 D 664 D 6854 D 6854

Property/ Date

Oxidation Stability (Hours) [min] Cloud Point (oF)

Cold Soak Filtration Test

(seconds) [max] Acid Number

(mg KOH/g) [max]Free Glycerin

(mass %) [max]Total Glycerin (mass %) [max]

2/12/2007 1.50 45 135 0.3 0.010% 0.200%2/11/2007 2.00 45 180 0.3 0.010% 0.200%2/10/2007 3.50 50 315 0.2 0.010% 0.200%2/9/2007 4.50 60 405 0.1 0.010% 0.200%2/8/2007 4.00 55 360 0.3 0.010% 0.200%2/7/2007 2.50 45 225 0.3 0.010% 0.200%2/6/2007 2.00 45 180 0.5 0.020% 0.240%2/5/2007 1.50 45 135 0.5 0.020% 0.240%

Click here first then enter new data in row 15



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Chemical Solutions• Make inhibitor treat rate control a priority in your

plant!Why biodiesel Is unstable?



Biodiesel Additive Personal Service Report

Mass Balance Treat Rate

Additive

Date Opening Kg Kg's Recv'd Ending Kg's Kg's UsedTonnes Biodiesel Treated (1000 Kg)

Kg's Biodiesel Treated

Treat Rate (ppmw)

2/12/2007 41,000 - 32,500 8,500 16,500 16,500,000 515 2/1/2007 30,000 20,000 41,000 9,000 18,300 18,300,000 492 1/1/2007 40,000 - 30,000 10,000 21,000 21,000,000 476

12/1/2006 29,000 20,000 40,000 9,000 18,100 18,100,000 497 11/1/2006 40,000 29,000 11,000 22,200 22,200,000 495 10/1/2006 20,000 30,000 40,000 10,000 20,100 20,100,000 498 9/1/2006 33,000 20,000 13,000 26,000 26,000,000 500

Anti-Oxidant EC 5208A

Click here first then enter new data in row 7



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Chemical Solutions• Make inhibitor treat rate control a priority in your

plant!Why biodiesel Is unstable?



Anti-Oxidant, EC 5208A Treat Rate Vs Target of 500 ppmw

-

100

200

300

400

500

600

9/1/

2006

9/8/

2006

9/15

/200

6

9/22

/200

6

9/29

/200

6

10/6

/200

6

10/1

3/20

06

10/2

0/20

06

10/2

7/20

06

11/3

/200

6

11/1

0/20

06

11/1

7/20

06

11/2

4/20

06

12/1

/200

6

12/8

/200

6

12/1

5/20

06

12/2

2/20

06

12/2

9/20

06

1/5/

2007

1/12

/200

7

1/19

/200

7

1/26

/200

7

2/2/

2007

2/9/

2007

pp

mw



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Summary

• Biodiesel is much more unstable than petro diesel

• This instability can result in quality complaints and significant liability for biodiesel producers and resellers

• Biodiesel stability can be efficiently managed through mechanical, operational and chemical best practices

• The biodiesel producer must recognize stability as a priority!






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Questions and Comments

• The biodiesel industry is new to us all

• No producer, marketer or vendor has all the answers

• Please share your experience and knowledge with the group......






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Biodiesel ….. Biodiesel ….. It’s Time Has ComeIt’s Time Has Come

the importance of biodiesel stability

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