556
and acetone using p-toluene sulfonic acid as the catalyst, with glycerol/acetone ratio
of 1:6 [337]. Formation of ketals with several types of ketones besides acetone like
butanone, cyclopentanone, 4-methyl-2-pentanone and 3,3-dimethyl-2-butanone
was investigated by De Torres et al. [338]. In the condensation of glycerol and
cyclopentanone, at a molar ratio 1:1 and at 60 °C temperature, 81.4% solketal was
obtained with fluorosulfonic resins (NR-50 and SAC-13) and K10-montmorillonite
as catalysts over a reaction time of 2 h. Condensation of glycerol with acetone in
continuous-flow mode using several heterogeneous catalysts (Amberlyst wet, zeolite, Amberlyst dry, zirconium sulphate, montmorillonite and polymax) was investigated by Nanda et al. [339]. Under optimized process conditions of 25 °C, acetone/
crude glycerol molar ratio of 4 and WHSV of 2 h
−1
, maximum yield of 94 ± 2%
solketal could be obtained [340] on Amberlyst wet catalyst, which could be regenerated and reused for another 24 h cycle, without any loss of activity.
Similarly, formation of acetals by condensation of glycerol with aldehydes,
using different types of acidic catalysts, has been studied extensively [322]. Like
ketals, acetals are useful as fuel additives and solvents in paint and pesticide industries. Umbarkar et al. [341] have studied acetalization of glycerol with different
aldehydes on well-characterized mesoporous MoO 3 /SiO 2 . Maximum conversion of
72% benzaldehyde with 60% selectivity to acetal was observed on 20% w/w MoO 3 /
SiO 2 at 100 °C in 8 h. Recent developments in the catalysts and features in the processes for acetalization of glycerol have been covered in a review by Amin
et al. [342].
Glycerol could be converted into a number of value-added chemicals/chemical
intermediates (Fig. 30) through chemo- and bio-catalytic routes as described in several reviews [21, 91, 95–99, 322, 323]. Apparently simple conversion like dehydration of glycerol to acrolein has been the subject of intensive studies, mainly devoted
to the development of catalysts that display maximum selectivity at optimum conversion and reasonable life/regenerability. Though Cs salt of heteropoly tungstic
acid supported on silica displayed 100% glycerol conversion and 98% selectivity
for acrolein, the stability of the active phase (leaching) was the challenge [343].
Similarly, on supported NiSO 4 catalyst, 90% glycerol conversion and 70% selectivity to acrolein could be achieved, but the catalyst was prone to deactivation due to
oxidation and loss of sulphur [344]. Multicomponent catalyst with W-Zr-Al active
phase, supported on hexagonal mesoporous silica (HMS) (MUICat-5), displayed
excellent stability, higher glycerol conversion (86%) but moderate acrolein selectivity of 60% [345]. Though zeolite-based catalysts are active at high GHSV (1438 h
−1
),
selectivity for acrolein is low [346]. A compilation of catalysts for dehydration of
glycerol from recent literature is presented in the review by Nda-Umar et al. [322].
Some of the strategies for extending the catalyst life and reactor design aspects are
discussed in another monograph by Cognet and Aroua [323].
Glycerol carbonate (GC) is the other glycerol derivative with widespread applications in the manufacture of polyurethanes, polyesters, polycarbonates and polyamides and useful as substitute for fossil-derived ethylene carbonate or propylene
carbonate. It is also used as solvent in the paint, battery and detergent industries as
well as in the synthesis of very valuable intermediates such as glycidol. GC is
R. Vinayagamoorthi et al.
and acetone using p-toluene sulfonic acid as the catalyst, with glycerol/acetone ratio
of 1:6 [337]. Formation of ketals with several types of ketones besides acetone like
butanone, cyclopentanone, 4-methyl-2-pentanone and 3,3-dimethyl-2-butanone
was investigated by De Torres et al. [338]. In the condensation of glycerol and
cyclopentanone, at a molar ratio 1:1 and at 60 °C temperature, 81.4% solketal was
obtained with fluorosulfonic resins (NR-50 and SAC-13) and K10-montmorillonite
as catalysts over a reaction time of 2 h. Condensation of glycerol with acetone in
continuous-flow mode using several heterogeneous catalysts (Amberlyst wet, zeolite, Amberlyst dry, zirconium sulphate, montmorillonite and polymax) was investigated by Nanda et al. [339]. Under optimized process conditions of 25 °C, acetone/
crude glycerol molar ratio of 4 and WHSV of 2 h
−1
, maximum yield of 94 ± 2%
solketal could be obtained [340] on Amberlyst wet catalyst, which could be regenerated and reused for another 24 h cycle, without any loss of activity.
Similarly, formation of acetals by condensation of glycerol with aldehydes,
using different types of acidic catalysts, has been studied extensively [322]. Like
ketals, acetals are useful as fuel additives and solvents in paint and pesticide industries. Umbarkar et al. [341] have studied acetalization of glycerol with different
aldehydes on well-characterized mesoporous MoO 3 /SiO 2 . Maximum conversion of
72% benzaldehyde with 60% selectivity to acetal was observed on 20% w/w MoO 3 /
SiO 2 at 100 °C in 8 h. Recent developments in the catalysts and features in the processes for acetalization of glycerol have been covered in a review by Amin
et al. [342].
Glycerol could be converted into a number of value-added chemicals/chemical
intermediates (Fig. 30) through chemo- and bio-catalytic routes as described in several reviews [21, 91, 95–99, 322, 323]. Apparently simple conversion like dehydration of glycerol to acrolein has been the subject of intensive studies, mainly devoted
to the development of catalysts that display maximum selectivity at optimum conversion and reasonable life/regenerability. Though Cs salt of heteropoly tungstic
acid supported on silica displayed 100% glycerol conversion and 98% selectivity
for acrolein, the stability of the active phase (leaching) was the challenge [343].
Similarly, on supported NiSO 4 catalyst, 90% glycerol conversion and 70% selectivity to acrolein could be achieved, but the catalyst was prone to deactivation due to
oxidation and loss of sulphur [344]. Multicomponent catalyst with W-Zr-Al active
phase, supported on hexagonal mesoporous silica (HMS) (MUICat-5), displayed
excellent stability, higher glycerol conversion (86%) but moderate acrolein selectivity of 60% [345]. Though zeolite-based catalysts are active at high GHSV (1438 h
−1
),
selectivity for acrolein is low [346]. A compilation of catalysts for dehydration of
glycerol from recent literature is presented in the review by Nda-Umar et al. [322].
Some of the strategies for extending the catalyst life and reactor design aspects are
discussed in another monograph by Cognet and Aroua [323].
Glycerol carbonate (GC) is the other glycerol derivative with widespread applications in the manufacture of polyurethanes, polyesters, polycarbonates and polyamides and useful as substitute for fossil-derived ethylene carbonate or propylene
carbonate. It is also used as solvent in the paint, battery and detergent industries as
well as in the synthesis of very valuable intermediates such as glycidol. GC is
R. Vinayagamoorthi et al.