Type of oxide

Regeneration process after filtration

Solvent (number of washing), temperature of drying or calcination (duration)

FAME or FAEE yield

% (1^st run to last run)

Runs number

Reference

CaO

CaO graphite oxide

500˚C

>90 with no significant loss

4

[25]

CaO from mud clam shells

Centrifugation, n-hexane, 900˚C

96.7 to 74.5

5

[38]

CaO

MeOH, dried, 850˚C

89 to 85

5

[39]

CaO

MeOH , 850˚C (2 h)

79.7 to 60.7

3

[58]

CaO used under ultrasonic cavitation

Centrifugation, MeOH, hexane, 500˚C (3 h)

50 to 40

3

[61]

CaO rich catalyst

Acetone, EtOH, 120˚C (overnight), 600˚C - 800˚C (4 h)

75 to 50

4

[64]

CaO from waste cokle shells

MeOH, n-hexane , 900˚C (2 h)

>97

3

[65]

Mixed or supported oxides

Sr/Mg = 0.20

750˚C under N₂ atmosphere

96.8 to 65

3

[9]

CaMgO

Hexane, MeOH, 800˚C (3 h)

>80

4

[11]

CaZnO

Hexane, MeOH, dried in oven (overnight), 800˚C (3 h)

80 with slight decrease

6

[11]

CaO-CeO₂

MeOH (3), 120˚C (5 h), 750˚C under He/O₂: 9/1

83

91

5

[13]

Zr/CaO

Hexane, 700˚C

99 to 80 to 40

1-3-4

[16]

Calcium silicate

600˚C (6 h)

100 to 90 to 70

1-3-8

[20]

K/LaMgO

MeOH, 550˚C

94 to 87

3

[30]

Hydrotalcite (Mg+Al)

MeOH (3), 200˚C (18 h)

90 to 60

3

[59]

Mg_1−x Zn_1+xO₂ (A-FR)

MeOH, 100˚C (48 h),

Dried, 461˚C (4 h 25)

78 to 68

78 to 77

4

[71]

CaO-NiO and CaO-Nd₂O₃

MeOH and hexane,

900˚C (3 h)

>80

6

[73]

CaMnOx

550˚C under O₂ and 750˚C under N₂

>90 with slight change

6

[75]

K doped MgO

MeOH, 700˚C(3 h) in air

>95

2

[79]

KF (40%)/bentonite catalyst

MeOH (several times), 500˚C (3 h)

98.2 to 93.3

5

[81]

KF/CaO

EtOH, 560˚C under air (10 h)

>90 with no apparent loss

14

[82]

K-pumise (CaO natural pumise)

EtOH, dried, 560˚C (10 h), new ionic exchange with KOH, 120˚C (3 h)

90 with no change

6

[88]

MgO-CaO/SiO₂

600˚C under N₂ flow

90.1 to 88.7

3

[91]