Effect of impurities in the crude glycerol polymerization reaction to produce polyglycerol

Abstract

Crude glycerol is a low-cost biodiesel industry co-product in a ratio of 1:10 with the main product. The large quantities of crude glycerol produced affect the biodiesel and glycerol markets. Consequently, the exploration of new applications for crude glycerol becomes crucial. As the composition of crude glycerol differs significantly from that of purified glycerol, this work was focused on studying the effect of crude glycerol impurities on its polymerization, as this process, at the same reaction conditions established for the polymerization of purified glycerol, did not result in polymeric products. To identify the reason for this result, the crude glycerol was fully characterized to identify its composition. Hence, an experimental design using simulated crude glycerol was performed to study the effect of the most abundant impurities in the raw glycerol on the polymerization andthe impurities that would persist with such reaction conditions, such as soap and sodium. The response variable for the experimental design was the hydroxyl number of the reaction products. FT-IR spectroscopy was used to analyze differences among the reaction products obtained from different treatments. The presence of soap was identified as primary inhibitory factor and the bottleneck in the formation of polyglycerol via polymerization of crude glycerol. Molecular weights of the polymerization reaction products were determined and analyzed as per the MALDI-TOF technique. The identification of the effect of impurities of crude glycerol polymerization suggests new routes for using it in the production of high value-added chemicals.

Glycerol polymerization degree effect on the emulsifying properties of polyglycerol esters

“…Results of reaction times, hydroxyl numbers, molecular weights, and molecular weight distributions of synthetized polyglycerols are summarized in Table 1. Different polymerization degrees due to etherification 24,25 were evidenced by changes in the hydroxyl number of the reaction products. The hydroxyl number of polymers obtained from polymerization of glycerol were lower than hydroxyl number of pure glycerol (1800 mg KOH/g) 26 .…”

An Evaluation of Glycerol Acetalization with Benzaldehyde over a Ferromagnetic Heteropolyacid Catalyst

“…It is crucial for many industries where glycerol is used as an intermediate compound to obtain added-value products by biochemical, chemical, thermochemical, or catalytic routes. This mainly focuses on the dehydration of glycerol to acrolein (an important chemical intermediate in many industries) [1][2][3], polymerization of glycerol to polyglycerols (surfactants used in the food, detergents, and cosmetics industries) [4][5][6][7], esterification to acylated esters -glyceryl diacetate, glyceryl triacetate (oxygenated fuel additives) [8][9][10], hydrogenolysis of glycerol to propandiol (an important intermediate in the polymer industry) [11][12][13], condensation with carbonyl groups to acetals and ketals (antiknock additives in combustion engines, oxygenated fuel additive, surfactant, and flavoring agent) [14], carboxylation to glycerol carbonate (electrolyte and solvent in batteries) [15,16], and the steam reforming of glycerol to hydrogen (fuel) [17][18][19]. Among them, the condensation of glycerol with carbonyl compounds (ketones and aldehydes) is one of the common glycerol valorization routes described in the literature because valuable cyclic acetals/ketals for various industries are obtained with the formation of H 2 O as a non-toxic co-product.…”