Improving the Cold Flow Properties of Biodiesel

Chor Huang and David Wilson

91 st AOCS’ Annual Meeting

San Diego, California

April 26, 2000

18071- 1

l Methyl esters of Rapeseed oil (RME) or Soybean Oil (SME)

l Receiving increasing attention in Europe and North America as an alternative to conventional diesel fuel

l Renewable, low toxic & biodegradable fuel

l Potential to lower exhaust particulate emissions (especially soot)

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RME - Typical Properties

PROPERTY

Viscosity 20°C (m&s)

DIESEL RME -

38 . 80 .

Calorific Value (kJ/kg) -37,200

Cetane Number > 50 -52

CFPP (“C) -31 -1 o,..-14

Sulfur (ppm) 350 3

Carbon Residue (%) 0.17 co.02

Carbon Content (%M) 75.8

RME - Cold Temperature Performance

l Despite the advantages of using RME, it has a number of unfavorable cold temperature properties

- Poor cold weather operability

- Unacceptably high Cloud Point (CP), Cold Filter Plug Point (CFPP) and Pour Point (PP)

l By careful choice of additives, individual cold flow properties (i.e. CP, CFPP and PP) can be improved.

Low Temperature Properties of RME

.

RME RME RME RME RME RME

#I #2 #3 #4 #5 #6

Cloud Point (“C) -6 -3 -4 -3 -3 -3

CFW”C) -15 -12 x x -9 -12

Pour Point. (“C) -38” -11 -16 -13 -9 -12

* Pour Point of RME 1 indicates presence of additive.

Pour Point Depressants (PPD’s)

l Widely used in oil industry to improve flow characteristics at low temperatures

l Effectiveness of six PPD’s determined in RME #l-7 - Malan-Styrene Esters, MSC (PPDI & PPD2) - Polymethacrylate, PMA (PPD3, PPD4 & PPD5) - Ethylene Vinyl Acetate, EVA (PPDG)

l CFPP and Pour Point goals set at -2O*C and -35°C respectively

PPD Chemistry

MALAN-STYRENE ESTER (MSC)

n

POLYMETHACRYLATE

(PMN

(-1 0.

n

;c=o R

ETHYLENE VINYL ACETATE (EVA)

Effectiveness of PPDI (MSC)

Additive treat level (%) -5 ’

0

-15

-45

Repeatability of CFPP

Repeatability in RME #5

Unadditized RME

0.75% PPD 1 -23 -25 -22 -24

0.50% PPD5

0.75% PPDl + 0.5% PPD5 -19 -19 -18 -19

Repeatability of Pour Point

Effectiveness of PPD2 (MSC)

Additive treat level -5

-25

Temperature (“C)

Temperature (“C)

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m

Effectiveness of PPD5 (PMA) _,,. j

-5

-45

Additive treat level (%I

Temperature (“C)

m

C (D

PPD Synergism

PPD + Additive treat level (%)

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E

0

-10

-20

-30

-40

-50

CFPP - Performance Stability

Additized=RME#6 stored at -15°C

Initial 4 weeks 8 weeks

0.75% PPDI (MSC) -23...-24 -24 -23

1.00% PPDI (MSC) -22~24 -25 -25

0.50% PPD5 (PMA) -Il...-12 -12 -12

0.75% PPDI + -18 -18 -18 0.50% PPD5

Pour Point - Performance Stability

Additized=RME#6 stored at -15°C

4 weeks 8 weeks

I 0.75% PPDI

I 1 .OO% PPDI

ri-T 0 5OY’ PPD5 -36...-42

I 0.75% PPDI + 0.50% PPD5

Constant Stress Rheometry

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2 E

1600

1400

1200

1000

800

600

400

200

0

-20 -15 -10 -5 0

Temperature (“C)

Effect on RME viscosity

KV40 specification (DIN V 51 606) = 3.5-5.0 cSt.

RME#l RME#2 RME#5 RME#6 RME#7

Pure RME 4.45 4.43 4.39 4.42 4.45

1% PPDl 4.86 4.88 4.85 4.82 4.81

CONCLUSIONS

l Low temperature properties of RME significantly improved by PPD#l (MSC)

- CFPP lowered to -22OC to -23°C - Pour point (PP) lowered to -39°C to -42°C

l Other PPD’s effectively reduced PP to below -35OC

l Combinations of PPDI 815 and PPD2 & 5 showed valuable synergistic effects with pour point

l Low temperature viscometrics showed PPD’s act as flow improvers. Viscosity at -19OC reduced from 1340 mPa to <IO0 mPa