Biodiesel Product Quality Challenges - Wayne State...

2008 © Fuel Quality Services, Inc.

Biodiesel Product Quality Challenges:Gaylord Palm Resort and Convention Center, Orlando Florida, February 4, 2008


Overview

• Introduction

• Product Quality Challenges

– Manufacturing

– Storage

• Conclusion.


Biodiesel is a novel fuel…


Made from renewable sources…

Vegetable Oil

Used Grease

Animal Fat


• Biodiesel and its blends power diesel engines…

• Biodiesel can be handled nearly like a petroleum diesel and…

• Biodiesel is being evaluated as a fuel feed stock for critical turbine engines.

Local Terminals Fueling

AviationFleets Rail MarineIndustrial

Emergency Systems

UtilitiesTelecommunications

Agriculture

Mining


Biodiesel is good for the environment…• It is very biodegradable,

• Exhaust emissions from biodiesel are lower in…

– CO & CO2,

– particulates,

– soot, and

– hydrocarbons


Biodiesel is good for our national security and economy…

• Domestically produced feedstocks reduce the need to import foreign crude oil,

• Domestic production of biodiesel reinvests into our domestic and local economies,


Are there Quality Issues…? • There certainly are…

• Unlike petroleum based diesel fuel, biodiesel is made from a perishable food source,

• Once certain product deterioration processes begin they are irreversible,

• Biodiesel product quality problems can go unnoticed for some time before creating operational issues,


MANUFACTURING


Production ProcessBiodiesel

Transesterification Process

Petroleum Diesel Separation Processvs.


Transesterification Comparison

Source: Understanding Biodiesel Fuel Quality and Performance

Soy Used GreaseAnimal Fat

+

(Catalyst NaOH / KOH)

FAME* + Glycerin + Byproducts

*Vegetable oils will contain natural antioxidants


Two Purification Processes • Wet Method:

– B100 is purified by spraying a fine water mist over the fuel and impurities are removed as the water droplets settle to the bottom of the tank,

– The advantage is that some natural antioxidants remain with the B100 to provide temporary protection against peroxide formation,

– Disadvantage is the additional water results in increased cost, production time and B100 with high water content (>1000ppm)

• Distillation Method:– B100 is purified from the unwanted by-products by distillation,

– The advantage is that the B100 is a much purer product

– The disadvantage is that the natural antioxidants do not carry over with the B100 and the product immediately begins peroxide formation,


Desired Products - Soy FAME (FAME Carbon Lengths C8-C22)

C16:0

C18:0

C18:1

C18:2

C18:3

Unsaturated Molecules

Saturated Molecules


Undesired Reaction Byproducts

Glycerin

Free Fatty Acids

Monoglyceride & Diglyceride

Methanol

Process Catalyst

NaOH / KOH


Potential Product Quality Issues

Issues similar to glycerinMono- & di-Glycerides

Corrosion of FIE, Filter Plugging

Sediment on parts

Provides electrolytes and hastens the corrosion of zinc, Salts of organic acids, Organic compounds formed

Fuel LeakageCauses swelling of some elastomers, nitrile rubbers to soften, swell or harden and crack

Free Fatty Acid

Filter clogging and Injector Coking

Corrodes non-ferrous metals, soaks cellulose filters, sediments on moving parts and lacquering

Free Glycerin

Source: Diesel Fuel Injection Equipment Manufacturers Common Position Statement

Failure ModeEffectCharacteristic

Blocked NozzlesPotassium and sodium compounds solid particlesProcess Catalysts

Low flash pointCorrodes aluminum & zinc, Corrosion of FIEMethanol Carryover


Oxidative Instability

• Saturated oils, fats and FAME:

– Have poor cold temperature characteristics,

– However, tend to be more stable against oxidative degradation formation,

• Unsaturated oils, fats and FAME :

– Have a better cold weather characteristics,

– However, have a greater propensity to undergo oxidative degradation more readily,


Storage Issues


Storage Issues

• Decades ago it was discovered that stored oils and fats would degrade (rancid) when exposed to oxygen. This was eventually solved by the use of antioxidants,

• Oils and fats will undergo degradation in the presence of certain oxygen species, metals and acids to produce peroxides and hydroperoxides,

• The rate of degradation depends on the number of double bonds per molecule and their relative location,

• Biodiesel is made from a variety of oils, fats and greases,


Reactive Sites

More Reactive

(Bis-Allylic Site)

Most Reactive

(Bis-Allylic Site)

Least Reactive

Reactive Sites

(Allylic Site)

C16:0

C18:0

C18:1

C18:2

C18:3

Saturated Molecules

Unsaturated Molecules


Reaction Sites

Unsaturated products tend to be less stable. The double bond makes it easier for allylic carbons to lose the hydrogen to form a radical.

H H

Allylic Carbon

H H

Bis - Allylic Carbon

Saturated products tend to be more stable reducing radical formation,

Methyl CarbonH H

HH HH

C CC


Peroxide FormationInitiation

H + X + XHH

H•Radical

H

Termination

+ Stable ProductO--O

--

O--O

--(c)

H• H•+ Stable Product(b)

+ H-AntioxidantH H

+ •AntioxidantH•

(a)

H

H H

Peroxide

Propagation

+ O2+ +

H•H• H HO--O

--

O--OH

--

HydroperoxideRadical•


Various Biodiesel FeedstocksWeight Percent of Fatty Acids in Fat and Oil Feedstocks


Storage B100, B20 & B5

• Studies suggest that B100 can be exposed to oxidation degradation immediately after production:

– Wet purification will carry over some of the natural antioxidants providing short term protection to B100,

– Distillation purification does not carry over the natural antioxidants from B100, therefore no short term protection.

– Non-vegetable based B100 do not contain natural anti-oxidants thus possess no short term protection.



• Oxidation Stability Index (Rancimat) studies have shown:

– B100 with an induction period <3hrs, will likely go out of specification for acid value and oxidation stability within 4 months with formation of free fatty acid (FFA) and insoluble deposits,

– Even B100 with an induction period >7hrs (from natural antioxidants), still could go out of specification for oxidation stability after approximately 4 months,



• Studies suggest that B100 should not be stored for more than several months (or shorter) unless treated with a synthetic antioxidant, (hindered phenolic compounds)

• Studies also suggests that B100 treated with an synthetic anti-oxidant and that demonstrate an induction period of >3hrs will,

– Produce a B5 that will remain stable for 12 months,

– Produce a B20 that should remain stable for 12 months,


Catalytic Effect of Metal Species

• Studies also indicate that FAME can undergo peroxide formation in the presence of metals,

• Certain metals can facilitate peroxide formation in FAME,

• For example copper appears to exert the greatest catalytic degradation affect on FAME products (Cu+2 + e-è Cu+3)

• This is why biodiesel and biodiesel blends should not come in contact with copper, yellow metals (copper alloys), zinc, etc.


Effects of Excess Water

• Traditionally, above ground and underground storage tanks contain a volume of free water on the bottom of the fuel storage tank which is drained seasonally,

• Generally, the greatest concern with water in petroleum fuel systems is corrosion and microbial growth which will lead to fuel degradation and microbially influenced corrosion (MIC),

• Unlike petroleum diesel, FAME products have a much greater propensity toward microbial degradation.


Various Biodeterioration Rates

* Reduce mineralization rate due in part to the need to oxidize the reduced hydrocarbon to the fatty acid

Biodiesel Metabolism EPA Standard 560/6-82-003,

87.7926.24*75.9578.4585.5486.4088.4986.9228

80.1921.0470.1270.4777.8378.4080.7279.1514

59.8413.2060.5758.3968.467.6866.3269.017

0.000.000000000

Dextrose#2

Diesel

Neat

Soy

Neat

Rape

Soy Methyl Ester

Soy Ethyl Ester

Rape

Methyl Ester

Rape Ethyl Ester

Days

CO2 Evolution (%)


Biodeterioration of Biodiesel Product

||O

O

CH3

Microbial enzymatic attack of the terminal methyl group

Fatty Acid Methyl Ester

||O

O-( + CH3 )

Free Fatty Acid Methyl Group


Biodegradation Order of Petroleum Fuels

(Comparison Discussion)

1. Linear & branched

hydrocarbons

2. Cyclic

(Unsubstituted/Substituted)

3. Aromatic & Polyaromatic

R


Biodeterioration Petroleum Product

n-Alkane

1° Alcohol

Aldehyde

CarboxylicAcid

OH

||O

||O

OH

[O2]

[O2]

[O2]Oxidation of the petroleum product makes the material more available for microbial metabolism

In its reduced form petroleum fuels slow to microbial degradation


Biodeterioration of FAME and Petroleum Diesel

||O

O-( + CH3 )

Free Fatty Acid Methyl Group

||O

O-

Oxidized Petroleum Product

( + H+ )

Proton


Conclusion


Putting Things Into Perspective

24

18 6

12

Biodiesel

(4 Hours)

Petroleum Diesel

(24 Hour)

(1900–2008), the petroleum industry has had a century to resolve many product quality issues dealing with:

• Manufacturing & Chemistry,• Material compatibility, • Long term storage,• MIC, etc.

(1990-2008), the biodiesel industry has had just 2 decades to address product quality issues involving: • Manufacturing & Chemistry,• Material compatibility, • Long term storage,• MIC, etc.


Manufacturing / Purchasing Considerations

• If manufacturing, B100 must meet ASTM Specifications (ASTM D67581- XX) to ensure consistent product quality especially regarding biodiesel blends,

• If purchasing B100, request a Certificate of Analysis (COA) to confirm product quality. Reject any B100 that fails to meet any of the ASTM Specification.


Long Term Use and Product Storage• For long term storage (not defined), the user should

consider monitoring several quality parameters of the blended fuel product to ensure product remains in specification such as – Formation of insolubles, – Peroxide Value (PV),– Total Acid Number (TAN)– Viscosity– Ester Content– Polymer Content,– Microbial Contamination


Long Term Use and Product Storage• Based on the surveillance results or the presence of

excess free water present in the storage tank, the biodiesel and biodiesel blends may need to be treated with the appropriate additive(s) to minimize on-going degradation mechanisms:

– Anti-Oxidants

– Metal Deactivators

– Multifunctional Stabilizer Packages

– Microbicides !!!!


Long Term Use and Product Storage

Microbicides!!!!Microbicides!!!!

Multifunctional Stabilizers

Metal Deactivator

AntioxidantsAntioxidants

BlendsB100


Industry Support

• Is the national trade association representing the biodiesel industry as the coordinating body for research and development in the US.

• BQ-9000 helps companies improve their fuel testing and greatly reduce any chance of producing or distributing inadequate fuel.

• BQ-9000 is open to any biodiesel manufacturer, marketer or distributor of biodiesel and biodiesel blends in the United States and Canada.


Reference Sources


Industry Peer Groups

ASTM D6751


THANK YOU.

Edward W. EnglishFuel Quality Services, Inc.

[email protected]


References1. T.W. Graham Solomons, Organic Chemistry,1976, pg. 755.

2. John Chandler, “Improving Cold Flow Performance of Biodiesel”, ASTM Biodiesel Workshop, December 4, 2005.

3. Gerhard Knothe and Robert O. Dunn, “Dependence of Oil Stability Index of Fatty Compounds on Their Structure and Concentration and Presence of Metals, 2003.

4. Empirical Study of the Stability of Biodiesel and Biodiesel Blends, NREL/TP-540-41619, May 2007.

5. Characterization of Biodiesel Oxidation and Oxidation Products, CRC Project N. AVFL-2b, August 2005.

Biodiesel Product Quality Challenges - Wayne State...

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