Green Acetylation of Solketal and Glycerol Formal by Heterogeneous Acid Catalysts to Form a Biodiesel Fuel Additive

Abstract

A glut of glycerol has formed from the increased production of biodiesel, with the potential to integrate the supply chain by using glycerol additives to improve biodiesel properties. Acetylated acetals show interesting cold flow and viscosity effects. Herein, a solventless heterogeneously catalyzed process for the acetylation of both solketal and glycerol formal to new products is demonstrated. The process is optimized by studying the effect of acetylating reagent (acetic acid and acetic anhydride), reagent molar ratios, and a variety of commercial solid acid catalysts (Amberlyst-15, zeolite Beta, K-10 Montmorillonite, and niobium phosphate) on the conversion and selectivities. High conversions (72-95%) and selectivities (86-99%) to the desired products results from using acetic anhydride as the acetylation reagent and a 1:1 molar ratio with all catalysts. Overall, there is a complex interplay between the solid catalyst, reagent ratio, and acetylating agent on the conversion, selectivities, and byproducts formed. The variations are discussed and explained in terms of reactivity, thermodynamics, and reaction mechanisms. An alternative and efficient approach to the formation of 100% triacetin involves the ring-opening, acid-catalyzed acetylation from solketal or glycerol formal with excesses of acetic anhydride.

Effect of Bio‐Based Aldehyde Structure on the Conversion and Selectivity Towards Glycerol Acetal Over Amberlyst‐46 by Using a Solvent‐Free Approach

“…They are shown to have good solubility and stability towards oxidation but hydrolyze in the presence of acid [4] . This class of compound and its derivatives also have shown potential in different applications including as surfactant, [5] fuel additives [6–8] and anti‐freezing agent [9,10] . Dodson et al.…”

“…[3] They are shown to have good solubility and stability towards oxidation but hydrolyze in the presence of acid. [4] This class of compound and its derivatives also have shown potential in different applications including as surfactant, [5] fuel additives [6][7][8] and anti-freezing agent. [9,10] Dodson et al (2014b) showed the anti-oxidant activity exhibited by aromatic glycerol acetal indicated wide range of potential of this class of compound in industrial application including biodiesel industry.…”

Continuous reactive coupling of glycerol and acetone – A strategy for triglyceride transesterification and in-situ valorisation of glycerol by-product

“…Various studies have been carried out on transformation of glycerol into valuable products, such as glycerol carbonate [16][17][18] and solketal [19][20][21][22]. Glycerol carbonate has applications as a curing agent in cement and concrete building, solvent for active medical ingredients in various pharmaceutical formulations, an electrolyte in lithium and lithium-ion batteries, and in production of various polymers and plastics [23,24].…”

Synthesis of 3-alkoxypropan-1,2-diols from glycidol: experimental and theoretical studies for the optimization of the synthesis of glycerol derived solvents

“…[20][21][22][23][24][25] Glycerol esters, ketals and ethers are commonly used as solvents and additives in cleaning, cosmetic, food and pharmaceutical industry. [26][27][28][29][30] Glycerol ethers stand out among other glycerol derivatives by their relative chemical inertness, which make them very suitable as solvents. Apart from the synthesis of glycerol tertbutyl ethers from glycerol and isobutene, deeply studied due to their use as biofuel additives, 31 the synthesis of alkyl glyceryl ethers from glycerol has been investigated in order to obtain a large class of compounds with tunable properties depending on the number and nature of the alkyl chains.…”