Etherification of glycerol to polyglycerols over MgAl mixed oxides

Influence of acid–base properties of calcined MgAl and CaAl layered double hydroxides on the catalytic glycerol etherification to short-chain polyglycerols

“…In those results, the best catalytic yields towards (DG + TG) ranged between 33% using homogeneous LiOH as catalyst [16], around 33% using homogeneous CsHCO 3 [17], 40% with a Mg/Al calcined layered double hydroxide [23] and 50% using a Mg/Fe calcined layered double hydroxide [24]. However, it is remarkable the high catalytic activity of calcined HCs considering their low values of BET specific surface area (Table 2).…”

“…They found that conversion increased with basicity but also Lewis acidity was involved in the mechanism. Maireles-Torres et al used calcined Mg/Al and Mg/Fe layered double hydroxides [23,24]. The highest conversion (50%) was found for a catalyst prepared using NaOH/Na 2 CO 3 as precipitant agent, with selectivity to di-and triglycerol of 85% and 15%, respectively at 493 K after 24 h of reaction.…”

Optimization of microwave-assisted etherification of glycerol to polyglycerols by sodium carbonate as catalyst

“…Some heterogeneous catalysts cannot be employed in industry because of the difficulty in production and high cost. Other disadvantages of heterogeneous catalysts include leaching of chemicals, solubility in polar solvent, low thermal stability, and high reaction temperature and long reaction time requirements [16][17][18]. For heterogeneous catalysts, especially, mesoporous materials are applied because they can improve selectivity though its limited pore size to favor low molecular weight oligomers, which are DG and TG [23].…”

“…Bigger oligoglycerol molecules such as pentaglycerols and the de-emulsifier cyclic diglycerols are not desired for food applications (JECFA, 1973;JECFA, 1989). The investigations of etherification of glycerol have been done by using both homogeneous and heterogeneous catalysts [16][17][18][19][20][21]. These studies were carried out by conventional heating which usually required longer reaction times.…”

Mixed oxides tuned with alkaline metals to improve glycerolysis for sustainable biodiesel production

“…Heterogeneous catalysis has gained importance in the field of basic catalysis, and different materials such as oxides [12][13][14][15][16], hydroxides [17] and organic modified mesoporous materials [18] have been studied. For this purpose, layered double hydroxides (LDH) have probably been the most studied materials as basic catalysts in the last few years, and there is a vast literature concerning catalysis with this kind of material [19].…”