Supporting Information

Glycerolysis with Crude Glycerin as An Alternative Pretreatment for Biodiesel Production from

Grease Trap Waste: Parametric Study and Energy Analysis

Qingshi Tu, Mingming Lu, Gerhard Knothe

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Table S1. Summary of the experimental conditions from literature for glycerolysis of fatty acidsReferences Acid Surfactant/Catalyst

FFA-to-glycerol ratio

Surfactant/Catalyst concentration

Temperature (°C) Duration Grade of glycerol

Hartman (1966)

C8:0;C10:0; C12:0;C14:0; C16:0;C18:0; C18:1;C18:2

None 1:1 (both mass and molar ratios)

N/A 180 0.5-10 h Analytical grade

Guner et al.(1996) C18:1 Sulfated iron oxide 1:1(mass ratio)

2.44, 3.47, 5.10, 7.62 wt% 180, 200, 220, 240 200 min Analytical grade

Sanchez et al. (1997)a C18:1 Y-zeolite 0.33:1, 1:1, 3:1

(molar ratio) 0.3,1,3,5 wt% 160,170,180 5 h Pure

Sanchez et al. (1997)b C18:1 Y-zeolite 1:1 (molar ratio) 5 wt% 180 3 h Pure

Szelag and Zwierzykowski

(1998)

C12:0;C14:0; C16:0;C18:0 and mixture (C18:0,

57%; C16:0, 30.8%; C18:1,

7.2%)

Sodium/Potassium Soaps

1:1 (molar ratio)

1:0.7; 1:0.11;1:0.15

(max/min=2.14)(Molar ratio;

Glycerol:Cat.)

140, 150, 160±1 6 h Analytical grade

Macierzanka and Szelag (2004)

C12:0;C14:0; C16:0;C18:0

ZnC 1:1 (molar ratio)

1:0.00625; 1:0.0125; 1:0.025;

1:0.05 (max/min=8)(Molar ratio;

Glycerol:Cat.)

130, 140, 150, 160±1 6 h Analytical grade

Szelag and Sadecka (2009) C12:0 NaC12H25SO4

(SDS)1:1.25 (molar

ratio)

0.001, 0.005, 0.01, 0.025, and 0.05

mol (max/min=50)150±1 6 h Propylene glycol

(C3H8O2)

Pouilloux et al. (1999) C18:1 ion-exchange resin 1:6 (molar ratio) NA 90 up to 50 h Pure

Pouilloux et al. (2000) C18:0 Na2CO3, MgO,

ZnO, PTSA 1:1 (molar ratio) 3 wt% 110 24 h NA

Sánchez, N., Martínez, M., and Aracil, J. (1997)a. Selective esterification of glycerine to 1-glycerol monooleate. 1. Kinetic modeling. Industrial & engineering chemistry research, 36(5), 1524-1528.Sánchez, N., Martínez, M., and Aracil, J. (1997)b. Selective esterification of glycerine to 1-glycerol monooleate. 2. Optimization studies. Industrial & engineering chemistry research, 36(5), 1529-1534.

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Table S2. Summary of the experimental conditions from literature for glycerolysis of oils or FAMEs

References Oil/Methyl Esters Surfactant/CatalystGlycerol to

Oil/ME ratioSurfactant/Catalyst

concentrationTemperature (°C) Duration Grade of glycerol

Kaufman and Garti (1982)

Methyl StearateMethyl Myristate NaOH 0.25:1-3:1 (molar

ratio) 0.15% 95-150 8 h Pure

Noureddini and Medikonduru

(1997)

Soybean oilME NaOH

ME:1:0.25-1:1(pure)

1:0.035-1:1.15 (crude)

(molar ratio for both)

ME: 0.1 wt% (pure)0.3-0.1 wt% (crude)

ME: 230-240 (pure)

200-210 (crude)30 min 1) Pure

2) Crude (purified from biodiesel production)

Oil:2.5:1(molar ratio) Oil:0.18 wt% Oil: 245 20 min

Noureddini et al. (2004) Soybean oil NaOH 2:1,2.5:1,3:1

(molar ratio) 0.18 wt% 200-240 25 min

1) Pure2) Crude (purified from biodiesel production)

Fregolente et al. (2006) soybean oil NaOH 0.18,0.24,0.3:1

(molar ratio) 0.14, 0.2, 0.26 wt% 190-210 90 min Pure

Echeverri et al. (2011) Soybean oil NaOH/NaOCH3 2.5:1 (molar ratio) dependent on the

transesterification 160,180,200,220 60 min1) Pure2) Crude (only MeOH removal)

Echeverri et al.(2013)a

Castor oilME

NaOHSoap 2.5:1 (molar ratio)

NaOH (1.7% of glycerin)

Soap (7.4% of glycerin)

180 (oil)180/200 (FAME)

30 min (oil)20/5 min (FAME)

88.1% purity glycerin

Echeverri et al.(2013)b Soybean FAME NaOH

Soap1.5-3:1 (molar

ratio)

NaOH (1.73% of glycerin)

Soap (7.41% of glycerin)

160-200 up to 60 min1) Pure2) 88.07% purity glycerin

Rukprasoot et al. (2005)

Palm stearin(98.7% with TAG,

1.3 DAG)

NaOH (only for pure glycerol)

2:1, 2.5:1, 3:1(molar ratio)

2.8 wt%180, 200, 230,

25015,20,30,60,90

min

1) Commercial grade (>95%);2) Crude (70% with 3.7% MAG, 2.8% Na2O

Schulz et al. (2011) FAME of linseed oil H2SO4, CaO,NaOH 3:1,4:1,5:1,6:1

(molar ratio) 0.5,1,5 130 0.5-15 h Pure

Felizardo et al. (2011)

20-50% FFA in acidulated soap-

stocksZn, AcZn 1:1.04~1:1.65

(molar ratio)0.1,0.2,0.3 wt%

(mass of Zn) 180,210,220,230 90,180 min Crude and neutralized by H2SO4

3

Gole and Gogate (2014) Nagchampa oil Zinc acetate 2:1

(molar ratio) 0.1% of oil 200240 min25 min

(microwave)Pure

Costa et al. (2015) Sludge from WWTP NA 1:2 (mass ratio) NA 200 120 min Pure

Kombe et al. (2013) Jatropha NA 2.24:1 (mass ratio) NA 65 73 min Pure

Kombe (2015) Castor NA 2.34:1 (mass ratio) NA 56 85 min Pure

Echeverri, D. A., Perez, W. A., and Rios, L. A. (2013a). Synthesis of maleated-castor oil glycerides from biodiesel-derived crude glycerol. Industrial Crops and Products, 49, 299-303.Echeverri, D. A., Cardeño, F., and Rios, L. A. (2013b). Glycerolysis of crude methyl esters with crude glycerol from biodiesel production. Journal of the American Oil Chemists' Society, 90(7), 1041-1047.

4

Table S3. Analytical results of FOG composition by ASTM D6584 method200 ºC FFA Glycerin MAG DAG TAGTime (min) min ave max min ave max min ave max min ave max min ave max

0 25.96 1.35 0.01 3.83 68.8530 0.93 17.76 0.47 0.14 0.14 0.10 1.22 1.31 0.89 2.15 23.79 2.37 3.77 56.99 4.4460 0.47 14.50 0.93 0.01 0.01 0.01 0.28 0.31 0.49 3.02 28.72 6.00 5.33 56.46 3.7790 3.50 11.92 2.80 0.00 0.00 0.01 0.26 0.28 0.31 1.87 26.21 0.99 1.53 61.59 2.78

120 4.21 9.82 2.81 0.00 0.00 0.01 0.28 0.29 0.35 2.33 22.95 4.58 5.92 66.94 6.82150 1.87 8.88 2.34 0.01 0.01 0.00 0.16 0.18 0.09 1.63 23.80 2.77 1.26 67.13 2.26180 1.87 7.48 2.34 0.00 0.00 0.00 0.12 0.13 0.09 3.48 25.57 6.78 5.01 66.81 3.89210 2.57 4.67 1.64 0.01 0.01 0.02 0.34 0.36 0.43 4.57 24.12 8.55 6.43 70.84 3.99240 0.47 2.57 0.24 0.00 0.00 0.00 0.07 0.09 0.10 2.64 20.20 1.43 1.59 77.13 3.14

215 ºC FFA Glycerin MAG DAG TAGTime (min) min ave max min ave max min ave max min ave max min ave max

0 25.96 1.35 0.01 3.83 68.8530 1.83 15.84 1.30 0.03 0.03 0.02 0.59 0.63 0.47 3.50 20.45 5.10 6.89 63.05 4.0460 2.96 11.38 1.87 0.00 0.00 0.01 0.34 0.38 0.43 3.80 19.80 4.76 6.28 68.44 4.2790 2.70 7.61 1.74 0.01 0.01 0.01 0.10 0.14 0.05 3.84 22.86 4.65 5.65 69.38 3.62

120 1.61 5.82 1.19 0.01 0.01 0.01 0.13 0.15 0.09 5.69 22.20 4.54 5.77 71.83 5.18150 2.49 4.59 1.64 0.01 0.01 0.00 0.12 0.14 0.14 6.96 23.56 8.57 9.57 71.70 5.34180 1.30 3.25 1.43 0.01 0.01 0.00 0.13 0.20 0.14 1.31 20.70 0.99 2.41 75.85 1.31210 0.68 3.02 0.88 0.00 0.00 0.00 0.15 0.17 0.09 5.38 25.18 7.15 7.03 71.64 4.65240 0.63 2.03 1.09 0.00 0.00 0.01 0.07 0.10 0.09 1.71 21.78 3.23 2.58 76.09 2.08

230 ºC FFA Glycerin MAG DAG TAGTime (min) min ave max min ave max min ave max min ave max min ave max

5

0 25.96 1.35 0.01 3.83 68.8530 3.37 8.05 4.42 0.01 0.01 0.01 0.66 0.69 1.08 1.67 29.55 2.31 2.08 61.69 1.4960 0.88 4.00 0.68 0.01 0.01 0.00 0.07 0.08 0.10 1.88 25.66 1.56 1.87 70.25 2.8090 1.15 2.55 2.13 0.01 0.01 0.01 0.05 0.06 0.06 2.24 23.99 1.67 0.59 73.39 0.42

120 1.56 1.56 2.34 0.00 0.00 0.00 0.17 0.18 0.15 0.87 25.76 0.85 3.02 72.50 1.64150 0.52 0.52 1.04 0.00 0.00 0.00 0.18 0.20 0.14 6.68 28.07 9.45 9.07 71.21 5.83180 0.26 0.26 0.52 0.01 0.01 0.01 0.04 0.06 0.03 1.62 25.78 3.05 2.82 73.89 1.67210 0.17 0.17 0.35 0.02 0.02 0.01 0.09 0.11 0.05 4.43 26.36 5.33 5.21 73.34 4.20240 0.00 0.00 0.00 0.00 0.01 0.00 0.09 0.12 0.14 8.53 26.14 5.62 5.76 73.74 8.62

Table S4. Design parameters of the key operation units in oil pretreatment and biodiesel productionEsterification Trans. from glycerolysis/esterification

FLASH Pressure 0.5 atm - Temperature 60 C -Distillation column # of stages 10 5 Pressure 0.1 atm 0.8 atm Reflux ratio 0.3 0.1

Table S5. Composition of high FFA oil, pretreated oil and resulting biodiesel from glycerolysis-transesterification (GT) and esterification-transesterification (ET) process routes

Mass % High FFA oil Pretreated oil BiodieselGT ET GT ET

Trioleina 70% 99.48% 62.54% 1.81% 1.29%Residual MeOH 30% - 9.34% 0.09% 0.06%Biodiesel - - 27.85% 88.9% 92.08%Oleic acida - 0.52% 0.27% - -Glycerin - - - 9.2% 6.57%aTriolein and oleic acid are used as the surrogates for mono-/di-/triglycerides and FFA

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Figure S1: a) manhole of the grease trap; b) heating raw trap grease at 105 ºC for 30 min; c) heating raw trap grease at 105 ºC for 24 h; d) the FOG collected after separation

Figure S2. Treated oil after glycerolysis process

Figure S3. (a) Crude biodiesel and glycerin mixture after 1st batch of water washing; (b) Purified biodiesel (top layer) and water (bottom layer)

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0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

-2.5

-2.0

-1.5

-1.0

-0.5

0.0f(x) = − 0.495712360165544 x − 0.0148016629042095R² = 0.943683519283246

t (h)

ln(C

FFA/

CFFA

0 )

Figure S4. Plot of ln(CFFA/CFFA0) vs t for glycerolysis conducted under 200 ºC, 1:1 glycerin-to-FFA molar ratio

8

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

-3.0

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

f(x) = − 0.606290920514111 x − 0.182396197004585R² = 0.982814334320404

t (h)

ln(C

FFA/

CFFA

0)

Figure S5. Plot of ln(CFFA/CFFA0) vs t for glycerolysis conducted under 215 ºC, 1:1 glycerin-to-FFA molar ratio

9

0.0 0.5 1.0 1.5 2.0 2.5

-4.5

-4.0

-3.5

-3.0

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

f(x) = − 1.42449912456008 x − 0.233343410542373R² = 0.973807797519585

t (h)

ln(C

FFA/

CFFA

0 )

Figure S6. Plot of ln(CFFA/CFFA0) vs t for glycerolysis conducted under 230 ºC, 1:1 glycerin-to-FFA molar ratio (4 h data point was not included as the reaction reached equilibrium after 3.5 h)

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Process simulation model for glycerolysisFigure S7 shows the process flow diagram (PFD) of the glycerolysis process. The operational condition is as follows, glycerin-to-FFA molar ratio=1:1 . The input oil and glycerin are mixed (MIX1) and the resulting flow (stream “MIXTURE”) is sent to a “RYield” reactor (R1). The choice of “RYield” over other types of reactors, such as stoichiometric reactor or Gibbs reactor, is due to the fact that no detailed kinetics data is currently available for the complex glycerolysis process. Therefore, this simulation uses the yield data (e.g. % of triglycerides in the glycerolysis product) from laboratory experiments (Table S3, 230°C, 150 min). After the reaction, the resulting mixture (stream “PROD-HOT”) is sent to a heat changer (HX1, approximately by a cooler with 80% energy recovery efficiency) to cool the treated oil to 65 C (stream “PROD-65”) for the subsequent transesterification step and to recover the heat for energy saving.

Process simulation model for acid-catalyzed esterificationThe PFD of esterification process is shown in Figure S8. Three input streams on the left are: high FFA oil (stream “OIL”), H2SO4 (stream “H2SO4”), and makeup methanol (stream “MAKEUP”). The recycled (excess) methanol stream is mixed with makeup methanol stream by a mixer (MIX3) and then mixed with H2SO4 stream via another mixer (MIX1). The high FFA oil and the MeOH-H2SO4 mixture are mixed (MIX2) and sent to a stoichiometric reactor (R1), where the conversion of FFA to fatty acid methyl ester (FAME) is assumed to be 99%. After the reaction, the treated oil mixture (steam “PROD-MIX”) goes through a flash evaporator (FLASH1) where the majority of methanol (with water) are evaporated (stream “MEOH-H2O”). The flash process is controlled such that sufficient amount of methanol are left in the bottom flow from the Flash (stream “PROD”) for the subsequent transesterification step. The “MEOH-H2O” stream is sent to a distillation column (COL1) to separate methanol from water. The top stream (steam “MEOH-REC”) from the distillation column contained recycled methanol with a high purity (>99%) and goes through a compressor (COM1) and a heat changer (HX1, approximately by a cooler with 80% energy recovery efficiency) before being mixed with the makeup methanol flow. The material dosage for the esterification process is determined from Chai et al. (2014): MeOH-to-FFA molar ratio 13:1, H2SO4=5 wt% of FFA, 60 C.

Process simulation model for transesterification of pretreated oilFigure S9 (a) and (b) show the PFD for transesterification of pretreated oil from glycerolysis and esterification processes. The reaction (with 98% conversion yield) is assumed to be carried out under a 6:1 molar ratio between methanol and oil (mono-/di-/triglycerides only), a catalyst dosage of 3.3 g NaOCH3 per L oil and 60 C. The major difference is the mass balance for methanol streams. As there is carry-over methanol from esterification process, no make-up methanol is necessary during transesterification in this case. The design parameters for the key operation units, such as flash and distillation column, are summarized in Table S4 for both glycerolysis-transesterification (GT) and esterification-transesterification (ET) routes.

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Figure S7. Process flow diagram (PFD) of glycerolysis process

12

Figure S8. Process flow diagram (PFD) of esterification process

13

Figure S9 (a). Process flow diagram (PFD) of transesterification process following glycerolysis

14

Figure S9 (b). Process flow diagram (PFD) of transesterification process following esterification

15

Figure S10. Overall retention times and peaks of components (FOG before reaction)

16

Figure S11. Retention times and peaks for diglycerides (FOG before reaction)

17

Figure S12. Retention times and peaks for monoglycerides (FOG before reaction)

18

0 30 60 90 120 150 180 210 2400.0

0.5

1.0

1.5

2.0

2.5

MAG

Glycerin

Time (min)

Actu

al C

once

ntra

tion

(wt%

)

Figure S13. Concentration of MAG and glycerin over time (200 ºC)

19

0 30 60 90 120 150 180 210 2400.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

MAG

Glycerin

Time (min)

Actu

al C

once

ntra

tion

(wt%

)

Figure S14. Concentration of MAG and glycerin over time (215 ºC)

20

0 30 60 90 120 150 180 210 2400.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

MAG

Glycerin

Time (min)

Actu

al C

once

ntra

tion

(wt%

)

Figure S15. Concentration of MAG and glycerin over time (230 ºC)

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24

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