TGA‐DTAGroup 4

Norazana, Daniel, Johan

BiofuelsGS‐2

Analytical techniques in combustion

Part 4, ÅA

• Comparison of DTA and TGA techniques

• Group works

G1. Indium (DTA)

G3. Oxalate (TGA) 

G2. KCl (TGA‐DTA)

G5. K2SO4 (TGA‐DTA)

G4. KCl‐K2SO4 eut mix (TGA‐DTA)

Presentation outline

Method approval

Phase diagram

DTA‐TGAone instrument – two functions

DTA 

• Temperature difference

• Thermocouple 

• Structural changes– Chrystallization

– Melting

• Chemical reactions causing temperature changes

TGA

• Mass change

• Microbalance

• Mass change by phase transition– Vaporization

– Sublimation

• Mass change by chemical reactions

Indium

• Standard for DTA

• Melting point:– Litterature: 156,6°C– Experimental: 153,95 °C

Method: Blank In-Al 25-700 °C_LF 25.0-700.0°C 30.00°C/min N2 50.0 ml/min

Method Name: Blank In-Al 25-700 °C_LF

Experiment: In-Al 25-700 °C_LF, 22.09.2009 16:10:35

SDTA In-Al 25-700 °C_LF,23.09.2009 10:29In-Al 25-700 °C_LF, 181.3201 mg

°C

-2.2

-2.0

-1.8

-1.6

-1.4

-1.2

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

min

°C50 100 150 200 250 300 350 400 450 500 550 600 650

0 2 4 6 8 10 12 14 16 18 20

^exo

SW 8.10eRTASLab: METTLER

Integral -37.96 s°C normalized -0.21 ks°Cg -̂1Onset 153.95 °CHeating Rate 30.00 °Cmin -̂1Result Mode Sample Temp

[]SDTA In-Al 25-700 °C_LF,23.09.2009 10:In-Al 25-700 °C_LF, 181.3201 mg

°C

-1.4

-1.2

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

min

°C120.0 130.0 140.0 150.0 160.0 170.0 180.0 190.0 200.0 210.0 220.0 230.0 240.0 250.0 260.0 270.0 280.0

3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5

^exo

SW 8.10eRTASLab: METTLER

Calcium oxalate, CaC2O4•H2O

• Common material to show the TGA performance

• Step 1: release of water

• Step 2: release of CO

• Step 3: release of CO2

Module: TGA/SDTA851e/LF1600/UMT5/552, 01.12.2004 14:28:43

Method Name: Blank, no Lid, Oxalate

Experiment: oxalate group 3, 22.09.2009 09:36:40

!oxalate group 3oxalate group 3, 7.0000 mg

%

40

50

60

70

80

90

100

min

°C50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44

SW 8.10eRTASLab: METTLER

-H2O

-CO

-CO2

KCl‐K2SO4 experiments

• In these experiments the 2 pure salts and an eutectic mixture were analyzed by DTA‐TGA 

• The results were compared with theoretical values

• In order to create a complete phase diagram of a salt mixture the melting behavior of the pure salts and several mixtures are needed.

Method KCl Pure KCl

KCl – K2SO4 eutectic mixture

ExpectedMp(KCl):  771 °CMp(Eut.): 690 °C

Temp prog.Start T: 25 °CEnd T: 830 °CHeating rate: 20 °C/minGas: N2Flow rate: 50 ml / min

1

N250 ml/min

°C

0

100

200

300

400

500

600

700

800

900

1000

min0 5 10 15 20 25 30 35 40 45 50

TG KCl blank 25-830_LF 22.09.2009 12:39:36

SW 8.10eRTASLab: METTLER

Pure KCl

• Melting point:– Litterature: 771 °C

– Experimental: 770,29 °C

Integral -66.57 s°C normalized -12.80 ks°Cg -̂1Onset 770.29 °CHeating Rate 20.00 °Cmin^-1Result Mode Sample Temp

[]SDTA KCl_100%_group2,22.09.2009 14:52:KCl_100%_group2, 5.2000 mg

°C

-2.4

-2.2

-2.0

-1.8

-1.6

-1.4

-1.2

-1.0

-0.8

-0.6

-0.4

-0.2

min

°C620 640 660 680 700 720 740 760 780 800 820

29 30 31 32 33 34 35 36 37 38 39

^exo

SW 8.10eRTASLab: METTLER

SDTA KCl_100%_group2,22.09.2009 14:52:35KCl_100%_group2, 5.2000 mg

°C

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

0.5

min

°C50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38

^exo

SW 8.10eRTASLab: METTLER

Pure K2SO4

• Phase transition:– Litterature: 587 °C

• Melting point:– Litterature: 1069 °C

Method: Blank + Lid_K2SO4 100%_25-1090_LF 25.0-1090.0°C 20.00°C/min N2 50.0 ml/min

Experiment: K2SO4 100%_25-1090_Group 5, 23.09.2009 13:49:24

SDTA !K2SO4 100%_25-1090_Group 5,K2SO4 100%_25-1090_Group 5, 4.1000 mg

°C

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0

0.2

0.4

0.6

0.8

min

°C50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000

0 5 10 15 20 25 30 35 40 45 50

^exo

SW 8.10eRTASLab: METTLER

???

Correct Baseline ??

Phase transition and meltingExperimental

• 582,54 °C • 1071,94 °C

Integral -20.93 s°C normalized -5.10 ks°Cg -̂1Onset 1071.94 °CHeating Rate 20.00 °Cmin^-1Result Mode Sample Temp

[]SDTA ! K2SO4 100%_25-1090_Group 5,K2SO4 100%_25-1090_Group 5, 4.1000 mg

°C

-1.8

-1.6

-1.4

-1.2

-1.0

-0.8

-0.6

min

°C1000.0 1005.0 1010.0 1015.0 1020.0 1025.0 1030.0 1035.0 1040.0 1045.0 1050.0 1055.0 1060.0 1065.0 1070.0 1075.0 1080.0 1085.0

48.6 48.8 49.0 49.2 49.4 49.6 49.8 50.0 50.2 50.4 50.6 50.8 51.0 51.2 51.4 51.6 51.8 52.0 52.2 52.4 52.6 52.8 53.0

^exo

SW 8.10eRTASLab: METTLER

Integral -4.21 s°C normalized -1.03 ks°Cg -̂1Onset 582.54 °CHeating Rate 20.00 °Cmin^-1Result Mode Sample Temp

°C

-0.10

-0.05

0.00

0.05

0.10

0.15

min

°C520.0 530.0 540.0 550.0 560.0 570.0 580.0 590.0 600.0 610.0 620.0 630.0 640.0 650.0

25.0 25.5 26.0 26.5 27.0 27.5 28.0 28.5 29.0 29.5 30.0 30.5 31.0

^exo

SW 8.10eRTASLab: METTLER

Sample preparationKCl – K2SO4 eutectic mixture

• 26 mole‐% K2SO4

• 74 mole‐% KCl

• 45 mg K2SO4

• 55 mg KCl

TGA curveKCl – K2SO4 eutectic mixture

!KCL-K2SO4 eut.mixt. 25-830°C_Group 4KCL-K2SO4 eut.mixt. 25-830°C_Group 4, 4.2000 mg

%

83

84

85

86

87

88

89

90

91

92

93

94

min

°C50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38

SW 8.10eRTASLab: METTLER

SDTA curveKCl – K2SO4 eutectic mixture

Integral -56.01 s°C normalized -13.34 ks°Cg -̂1Onset 683.85 °CHeating Rate 20.00 °Cmin^-1Result Mode Sample Temp

Integral -2.07 s°C normalized -0.49 ks°Cg -̂1Onset 580.08 °CHeating Rate 20.00 °Cmin^-1Result Mode Sample Temp

Method Name: KCl blank 25-830_LF

Experiment: KCL-K2SO4 eut.mixt. 25-830°C_Group 4, 24.09.2009 10:09:58

!SDTA KCL-K2SO4 eut.mixt. 25-830°C_GroupKCL-K2SO4 eut.mixt. 25-830°C_Group 4, 4.2000 mg

k°Cg -̂1

-0.50

-0.45

-0.40

-0.35

-0.30

-0.25

-0.20

-0.15

-0.10

-0.05

0.00

0.05

min

°C50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38

SW 8.10eRTASLab: METTLER

Integral -5.48 s°C normalized -1.30 ks°Cg -̂1Onset 579.42 °CHeating Rate 20.00 °Cmin -̂1Result Mode Sample Temp

°C

-0.14

-0.12

-0.10

-0.08

-0.06

-0.04

-0.02

0.00

0.02

0.04

min

°C530.0 540.0 550.0 560.0 570.0 580.0 590.0 600.0 610.0 620.0 630.0 640.0

25.5 26.0 26.5 27.0 27.5 28.0 28.5 29.0 29.5 30.0 30.5 31.0

^exo

SW 8.10eRTASLab: METTLER

Phase transformation peakKCl – K2SO4 eutectic mixture

Phase Transformation 587 °C

Integral -51.87 s°C normalized -12.35 ks°Cg -̂1Onset 683.87 °CHeating Rate 20.00 °Cmin^-1Result Mode Sample Temp

k°Cg -̂1

-0.50

-0.45

-0.40

-0.35

-0.30

-0.25

-0.20

-0.15

-0.10

-0.05

0.00

min

°C630.0 640.0 650.0 660.0 670.0 680.0 690.0 700.0 710.0 720.0 730.0

30.0 30.5 31.0 31.5 32.0 32.5 33.0 33.5 34.0 34.5 35.0

SW 8.10eRTASLab: METTLER

Melting peakKCl – K2SO4 eutectic mixture

Mp. 690 °C

TGA‐DTAKCl – K2SO4 eutectic mixture

°C

-2.2

-2.0

-1.8

-1.6

-1.4

-1.2

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0.2

min

°C50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38

%

83

84

85

86

87

88

89

90

91

92

93

94

min0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38

^exo

SW 8.10eRTASLab: METTLER

DTA

TGA

[°C] KCl Eut. Mix. K2SO4

PT theory ‐ 587 587

PT exp. ‐ 580,08 582,54

MP theory 771 690 1069

MP exp. 770,29 683,85 1071,94

PT = phase transition

MP = melting point

Summary

Conclusions

• KCl and K2SO4 system:

DTA results are in good agreement with the theoretical phase diagram

• Depending on fuel mixtures the melting range of the possibly forming salts have to be taken into careful consideration