Glycerine esterification with free fatty acids: Homogeneous catalysis

Study on the Formation Mechanism of Cold-Rolled Sludge and the Biodiesel Production from Sludge

Cold-rolled sludge (CRS) has become a challenge due to its large volumetric capacity and high toxicity and is difficult to be degraded under natural conditions. This article aims to explore the feasibility of the solvent extraction method for recovering oil and fat from CRS and utilizing it as a raw material to prepare biodiesel with the application of a homogeneous catalyst H2SO4 to mediate esterification and transesterification. The formation mechanism of CRS was proposed with its detailed analysis; hydroxylates were preferentially adsorbed on the metal surface by hydrogen bonds, and free fatty acids were hooked by carbon chains to form a second layer of adsorption. It revealed the reason for the residual oil content on the surface of the extracted solid phase. Experimental data represented an optimum biodiesel yield of 96.5% at a catalyst dosage of 25 wt %, a reaction time of 24 h, a methanol-to-oil molar ratio of 70:1, and a reaction temperature of 60 °C. The main properties of the biodiesel were tested and confirmed to meet ASTM D6751 standards.

Critical Review of the Various Reaction Mechanisms for Glycerol Etherification

This review provides in-depth coverage of numerous mechanisms available for the etherification process of glycerol, including alcohol solvent, olefin solvent and solvent-free routes along with products that are formed at various stages of the reaction. Mono tert-butyl glycerol ether (MTBG), di tert-butyl glycerol ether (DTBG), and tri tert-butyl glycerol ether (TTBG) are the three general ether compounds obtained through tert-butyl alcohol (TBA) etherification. Glycerol etherification with n-butanol results in the formation of glycerol ether products that are linked to the substituted butyl groups. These products include two mono-butyl glycerol ethers, two di-butyl glycerol ethers and a tri-butyl glycerol ether. Two mono-benzyl glycerol ether isomers, two di-benzyl glycerol ether isomers and tri-benzyl glycerol ether are the most reported results when benzyl alcohol is used as a solvent in the etherification reaction. The etherification of glycerol with 1-butene involves a series of equilibrium reactions to produce mono-ethers, di-ethers, and tri-ethers, whereas the etherification of glycerol with isobutene is carried out via tert-butylation of glycerol, yielding similar glycerol ether products when TBA is used as a solvent. As the by-product may be easily removed, the solvent-free glycerol etherification approach may have several advantages over the other conventional methods. Therefore, further studies on base-catalyzed glycerol etherification that employs a solvent-free reaction route may reveal a method for improving the conversion, selectivity, and yield of reaction products. This review study is crucial in improving knowledge of numerous mechanisms and how they relate to the effectiveness of the product’s catalytic process.

Production of Sustainable Biochemicals by Means of Esterification Reaction and Heterogeneous Acid Catalysts

In recent years, the use of renewable raw materials for the production of chemicals has been the subject of different studies. In particular, the interest of the present study was the use of oleins, mixtures of free fatty acids (FFAs), and oleic acid to produce bio-based components for lubricants formulations and the investigation of the performance of a styrene-divinylbenzene acid resin (sPSB-SA) in the esterification reaction of fatty acids. This resin has shown good activity as a heterogeneous catalyst and high stability at elevated temperatures (180 °C). It was tested in the esterification reaction of oleic acid with 1,3-propanediol and of oleic acid with glycerol. In particular, the esterification reactions were performed in a steel stirred batch reactor and a PBR loop reactor. Tests were conducted varying the reaction conditions, such as alcohol type, temperature, reaction time, and catalysts, both homogeneous and heterogeneous ones. From the obtained results, acid resin (both in reticulated and not-reticulated form) showed high activity in esterification reaction of oleic acid with 1,3-propanediol and of oleic acid with glycerol and good resistance to the deactivation; thus, they can be considered promising candidates for future applications in continuous devices. Viscosity tests were performed, underlining the good properties of the obtained products as lubricant bases.