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Shelf llfe determination and Shelf llfe determination and
antioxidant additives evaluation antioxidant additives evaluation
of soya bean mehyl biodiesel of soya bean mehyl biodiesel
stored in 1L steel containers stored in 1L steel containers
in tropical environments & in tropical environments &
corrosion behavior studiescorrosion behavior studies
Eduardo H S Cavalcanti & Vera Eduardo H S Cavalcanti & Vera ResendeResende
Corrosion & Degradation Corrosion & Degradation DivisionDivision
Rio de Janeiro, 01/10/2013Rio de Janeiro, 01/10/2013
•WBS 2013
7th World Bioenergy Symposium/COPPE-UFRJ
SummarySummary
IntroductionIntroduction
Testing MethodologyTesting Methodology
ResultsResults
CommentsComments
ConclusionsConclusions
INT’s Historical Background in INT’s Historical Background in BiofuelsBiofuels
19801980
19771977
19251925 19831983
19831983
19871987
19861986
19831983
19911991
70-80’s : FED GOVERNMENT R&D PROGRAMME > OLVEG
BABASSU BURITI SOY PALM SUN CASTOR FLOWER OIL
DENDÊ
INT’s Historical Background in INT’s Historical Background in BiodieselBiodiesel
1978 INT’s Governmental . Funded (FINEP) Project
Rio urban buses trials : peanuts oil preliminary tests Also tested ternary mixtures: diesel + Anh. Ethanol <3% + peanuts oil <20% = INTOL Mixture First trials: intense erosion in the engines' components
using pure oils Improvements were however observed when using esters rather than pure vegetal oil
MotivationMotivation
National Biodiesel Governmental Program launchedNational Biodiesel Governmental Program launchedin 2003 -> today 2nd largest world producer: 1,76 BLin 2003 -> today 2nd largest world producer: 1,76 BL
Large continental country (8 500 000 kmLarge continental country (8 500 000 km22) : 7 Biomass) : 7 Biomass
Great diversity of climates; high humidity and Great diversity of climates; high humidity and temperature variationstemperature variations
Predominance of types of biodiesel such as soya,Predominance of types of biodiesel such as soya,highly instable in terms of oxidation that requires highly instable in terms of oxidation that requires compulsory antioxidant additivation in order to guaranteecompulsory antioxidant additivation in order to guaranteequality on the delivery pointsquality on the delivery points
Most producers concentrated on the Southwest & SouthMost producers concentrated on the Southwest & South
Great logistical effort & many stakeholders involvedGreat logistical effort & many stakeholders involved
B5 introduced in 2010 > complains reported by B100B5 introduced in 2010 > complains reported by B100consumers and diesel dealersconsumers and diesel dealers
Biodiesel chemical instability > Limited shelf lifeBiodiesel chemical instability > Limited shelf life
Antioxidants efficiency needed to be assessed in the fieldAntioxidants efficiency needed to be assessed in the field
MotivationMotivation: : Biodiesel Real Life Storage & Logistic Biodiesel Real Life Storage & Logistic
ChallengesChallenges
Operational Aspects
Transportation, Handling,, Storage Stability & Related Problems (Sediments & Microbial Sludge Formation) , Distribution & Retail
Contatc with
Cu,Zn, Fe, Mn, etc.
O2 H2 O
Microbial Contamination
High Humidity Seasons & Regions
Crystallization and
Cold filter plugging
Corrosion
Oxidation
Oxidation
Biodiesel
Free Radicals
Peroxides
By products > Oligomers
O2
Complex reaction mechanismsComplex reaction mechanisms
• • Generally hydroperoxides Generally hydroperoxides OOHOOH initially formedinitially formed ll -CH--CH-
• • Variety of (secondary) reactions leading to different Variety of (secondary) reactions leading to different products including shorter-chain compounds, free products including shorter-chain compounds, free fatty acids, aldehydes, other oxygenates, higher fatty acids, aldehydes, other oxygenates, higher molecular weight materialsmolecular weight materials. .
• • Dependence on various parametersDependence on various parameters..
Factors that influence oxidation
Kind of feedstockContact with metalsTemperatureTime for antioxidant addition Fabrication Process (Temperature) >> residual natural antioxidants presence (e.g. tocopherols)Exposure to air and humidity
0% 20% 40% 60% 80% 100%
SOYA
SUNFLOWER
CORN
COTTOM
CANOLA
PALM
COCONUT
The higher the unsaturation degree higher is the oxidation susceptibility Antioxidant addition are of paramount importance to retard the oxidation processes of soya biodiesel
Raw Materials > Vegetal OilsRaw Materials > Vegetal Oils
SATURATED SATURATED MONOINSATURATED MONOINSATURATED POLINSATURATED POLINSATURATED
Antioxidants
Compulsory utilization in soy biodiesel
MaterialsMaterials
Brazilian Soy Methyl Ester > Biodiesel (SOMB100)
SOMB100 > produced by ADM In accordance to Brazilian B100Spec ANP 014//2012 withoutadditivation
Identification Concenttion Basic Composition
Pure SOMB 0 ppm No Additives Added
Additive 1 250 ppm Phenolic compounds
Additive 2 250 ppm Hidroquinone/ Glicol Salts
Additive 3 250 ppm Phenolic Compounds
Additive 4 250 ppm2,2-Methylen-bis(4-methyl-6-tert-butyl-
phenol)
Additive 5 250 ppm Phenolic Compounds
5 Antioxidants tested
MethodologyMethodology
Rancimat Test (EN 14112)
Based on Hadorn & Zurcher [1974] proposed test for olive oil ageing assessment .
Also known as Rancimat test: 3g of biodiesel exposed to an air flux (10 L/h) a 110ºC
As volatilization of organic acids increases demineralized water conductivity raises
Sudden increase indicates setting up of propagation stages of oxidation
PI = Oxidation Stability Index (OSI) > reflects the antioxidation reserve of the biodiesel
Longer IEO > better long term behavior > usually OSI > 6hs are acceptable by EU and Brazilian Specs at the factory
Antioxidants tends to increase IEO
MethodologyMethodology
800 mL of non additive containing soya biodiesel kept inside 1L steel container vessels
Local humidity and temperature daily monitored
Shelf Life Tests
Characteristics weekly monitored on top of IEOAppearance (ASTM Turbidity Haze Chart – ASTM 4176)
Water Content (Karl Fisher Coulometric – ASTM D 6304)
Kinematic Viscosity at 40ºC (ASTM D 445)
Specific Gravity at 20ºC (ASTM D 4052)
Testing MethodologyTesting Methodology
Samples Characterization and Preparation
Coupons: C steel AISI 1020 -> 40 mm x 25 mm x 2 mm -> grinded up to # 220Injection Components -> as received conditions provided by BoschMass measurements -> high precision scale: ± 0.01 mg accuracy
Photographic and Surface Characterization: Optical & 3D IFM DigitalSurface Analysis
Testing MethodologyTesting Methodology
Immersion & Corrosion TestsImmersion & Corrosion Tests
In accordance to ASTM G1 and G31 Corrosion Tests Stand. MethodsIn accordance to ASTM G1 and G31 Corrosion Tests Stand. Methods Quadruplicate samplesQuadruplicate samples
25ºC 25ºC ± 2 ºC± 2 ºC
43ºC ± 0.143ºC ± 0.1 ºC (ASTM D 4625)ºC (ASTM D 4625)
Six Weeks Duration Immersion TestsSix Weeks Duration Immersion Tests
ResultsResults
INT’s Local Temperature & RU% Monitoring
Average Temperature: 28ºC >Temperature ranges: 24-30ºCAverage UR%: 50% > Range: 30 to 70%
ResultsResults
Pure SOMB Quality Monitoring in 1L Storage Tanks Tests Pure SOMB Quality Monitoring in 1L Storage Tanks Tests
Non Additive containing B100 Quality Monitoring With Time
Time (Weeks)
Appearance
Water Content (mg/kg) Viscosity 40°C (mm2/s) Specific Gravity(kg/m3)
T0 OK 255.55 4.10 881.33
T1 OK 305.11 4.13 881.90
T2 OK 398.34 4.17 882.53
T3 OK 415.76 4.25 883.56
T4 OK 498.44 4.35 883.94
T5 OK 677.47 4.37 884.07
T6 OK 808,.48 4.45 885.00
Limited Shelf Life: Out of specification from the 5th week onwardsLimited Shelf Life: Out of specification from the 5th week onwards
ResultsResults
B100 Quality Monitoring in Storage Tanks Tests B100 Quality Monitoring in Storage Tanks Tests
LImited shelf life under storage conditions of B100LImited shelf life under storage conditions of B100
ResultsResults
IEO Monitoring in 1L Storage Tanks Tests IEO Monitoring in 1L Storage Tanks Tests
Limited Shelf Life to 4 Weeks in terms of Oxidation StabilityLimited Shelf Life to 4 Weeks in terms of Oxidation Stability Out of specification from the 4th week onwardsOut of specification from the 4th week onwards
Only one Additive was capable of keeping the oxidation stability in Only one Additive was capable of keeping the oxidation stability in accordance to Brazilian ANP Specification (IEO>6hs) accordance to Brazilian ANP Specification (IEO>6hs)
T 0W T 4W T 8W T 12W T 16W
Additive 0 4,65h 2,71h 1,82h 1,18h 1,00h
Additive 1 10,10h 6,50h 4,73h 3,21h 2,15h
Additive 2 10,29h 5,47h 3,31h 2,07h 1,78h
Additive 3 9,03h 5,12h 2,31h 0,72h 0,32h
Additive 4 7,22h 4,76h 3,13h 2,07h 1,80h
Additive 5 9,28h 5,17h 3,31h 2,34h 2,20h
Corrosion ResultsCorrosion Results
Appearance of the coupons surface after 6 weeks of immersion at 25ºC
No pitting & no evidence of uniform attack at X200 magnificationAverage roughness of profile: Ra = 399 nm
ResultsResults
Appearance of the coupons surface after 6 weeks of immersion at 25ºC
No pitting & no evidence of uniform attack at X200 magnificationAverage roughness of profile: Ra = 399 nm
ResultsResults
Appearance of the coupons surface after 6 weeks of immersion at 43ºC
No pitting & no evidence of uniform attack at X200 magnificationAverage roughness of profile: Ra = 503 nm
ResultsResults
Corrosion rates after 6 weeks of immersion at 25ªC and 43ºC
FuelFuel Sample TypeSample Type Average Corrosion Rate Average Corrosion Rate (mm/yr) at 25ªC(mm/yr) at 25ªC
Average Corrosion Rate Average Corrosion Rate (mm/yr) at 43 ºC(mm/yr) at 43 ºC
SOMB100SOMB100
C Steel C Steel Rectangular Rectangular CouponsCoupons
0.00550.0055 0.0110.011
SOMB5%SOMB5%
C Steel C Steel Rectangular Rectangular CouponsCoupons
0.00120.0012 0.00280.0028
Negligible corrosion rates !Negligible corrosion rates !
ResultsResults
Corrosion behavior of injection system components after 6 weeks of immersion at 25ªC and 43ºC
FuelFuel Sample TypeSample TypeOptical Optical ExaminationExamination
Average Mass Average Mass Change (mg) Change (mg) at 25 ºCat 25 ºC
Average Mass Average Mass Change (mg) at Change (mg) at 43ºC43ºC
SOMB100SOMB100
Armature Plate
No local No local attack < 2 µm attack < 2 µm
resolutionresolution<0,01 mg <0,01 mg <0,02 mg<0,02 mg
SOMB100SOMB100No local No local
attack < 2 µm attack < 2 µm resolutionresolution
<0,01 mg<0,01 mg <0,02 mg<0,02 mg
No corrosion observed!
ResultsResults
Corrosion behavior of injection system components after 6 weeks of immersion at 25ªC and 43ºC
FuelFuel Sample TypeSample TypeOptical Optical ExaminationExamination
Average Mass Average Mass Change (mg) at Change (mg) at 25 ºC25 ºC
Average Mass Average Mass Change (mg) at Change (mg) at 43ºC43ºC
SOMB5%SOMB5%No local attack < 2 No local attack < 2
µm resolutionµm resolution
<0,01 mg<0,01 mg <0,01 mg<0,01 mg
SOMB5%SOMB5%No local attack < 2 No local attack < 2
µm resolutionµm resolution<0,01 mg<0,01 mg <0,01 mg<0,01 mg
No corrosion observed !
Corrosion Studies CommentsCorrosion Studies Comments
B100 Coupons: Negligible average corrosion rates (CRs) were observed
According to the literature (M.G. Fontana 1986): CRs < 0.02 mm/yr can be associated with materials showing an outstanding corrosion resistance
Fontana’s relative corrosion resistance scale ranks the present
materials as on top of the list: e.g. level 5 correspond to excellent
corrosion resistance grade for these applications
Irrespective of the changes on the B100 chemistry at the final stages of
the experiment the average corrosion rates remained within the 0.02
mm/yr limit
ConclusionsConclusions
Shelf life of soy biodiesel under storage conditions was limited to 4
weeks
Only one additive was capable of keeping the oxidation stability in Only one additive was capable of keeping the oxidation stability in
accordance to Brazilian ANP Specification (IEO>6hs) in the long accordance to Brazilian ANP Specification (IEO>6hs) in the long
term but also limited to 4 weeks term but also limited to 4 weeks
TheThe study has showed the importance of when selecting a study has showed the importance of when selecting a
antioxidant to also take in consideration the long term field behavior antioxidant to also take in consideration the long term field behavior
and not rely only on Rancimat standardized factory testing carried and not rely only on Rancimat standardized factory testing carried
out on freshly produced biodiesel, particularly in tropical and out on freshly produced biodiesel, particularly in tropical and
continental countries of complex logistics like Brazil.continental countries of complex logistics like Brazil.
ConclusionsConclusions
Considering the behavior of carbon steel coupons and injection system
components maintained immersed for 6 weeks at 25ºC and 43ºC in B100
and B5 blend no evidence of uniform corrosion as well as no visible extent
of localized corrosion (at 200X magnification) were noticed
Considering the complex logistics of the Brazilian market and the present
needs of the biodiesel manufacturing industries better antioxidants
showing a long term performance, e.g. at least 60 days, shelf life are
needed to developed
Irrespective of the changes on the B100 chemistry at the final stages the
average corrosion rates remained within the 0.02 mm/yr limit
PETROBRAS PETROBRAS
ACKNOWLEDGMENTSACKNOWLEDGMENTS
UFPBUNBUFRJ
OBRIGADO !OBRIGADO !
Dr. Eduardo CavalcantiDr. Eduardo CavalcantiINT/DCOR/LACORINT/DCOR/LACOR
e-mail: [email protected]: [email protected]. (55 21) 2123 1198/1210Tel. (55 21) 2123 1198/1210
(55 21) 96128487(55 21) 96128487
