Search Results (3)

In this work, tin and zinc salts of silicotungstic and phosphotungstic acids were synthesized, characterized, and tested as catalysts for esterification reactions of glycerol with acetic acid (HOAc) to produce glycerol esters such as monoacetyl glycerol (MAG), which are used as additives in the pharmaceutical and food industries and in the manufacturing of explosives, or, in the case of di- or triacetyl glycerol (DAG and TAG), green bioadditives for diesel or gasoline. The activity of metal-exchanged salts (Zn, Sn) in H₃PW₁₂O₄₀ and H₄SiW₁₂O₄₀ heteropolyacids was evaluated in esterification reactions at room temperature. Among the catalysts tested, Sn_2/3PW₁₂O₄₀ was the most active and selective toward the glycerol esters. The process’s selectivity can be controlled by changes to reaction conditions. The maximum selectivitiesy of DAG and TAG were 60% and 30%, respectively, using a 1:3 molar ratio of glycerol/HOAc and a Sn_3/2PW₁₂O₄₀/673 K catalyst load of 0.4 mol%. Under these conditions, a glycerol conversion rate of 95% was observed and selectivity towards DAG and TAG was observed at 60% and 30%, respectively. The results were achieved after an 8 h reaction at a temperature of 333 K. The Sn_3/2PW₁₂O₄₀/673 K catalyst demonstrated the highest efficiency, which was attributed to its higher degree of acidity. Full article

In this work, a series of vanadium-substituted phosphomolybdic acids were synthesized and tested as the catalysts for the synthesis of solketal, a green fuel bioadditive, from the condensation reaction of glycerol with acetone. The objective was to demonstrate that an easily synthesizable solid catalyst can efficiently promote glycerol condensation with acetone at room temperature. The activity of pristine heteropolyacid (i.e., H₃PMo₁₂O₄₀) and its vanadium-substituted cesium salts (Cs_3+nPMo_12-nV_nO₄₀; n = 0–3) was evaluated in condensation reactions carried out at room temperature. Among the catalysts tested, Cs₄PMo₁₁VO₄₀ was the most active and selective towards a five-member ring solketal isomer (dioxolane). A high yield of solketal (i.e., 95% conversion and 95% selectivity to solketal) was achieved in glycerol condensation with acetone at room temperature within a short reaction time (2 h). The influence of the main reaction parameters, such as the acetone–glycerol molar ratio, catalyst load, and reaction temperatures, was investigated. The greatest activity of the Cs₄PMo₁₁VO₄₀ catalyst was correlated to its greatest acidity. Full article

Currently, the global issue for countries is the search for raw materials and the production of bioenergy within their country; bioenergy also includes biodiesel fuels. One of the most promising biodiesel fuels is the green diesel fuel produced by the hydrogenation of vegetable oils. Three methods have been proposed to obtain high-quality biodiesel and environmentally friendly diesel fuel: compounding green diesel with hydro-treated diesel fuel, compositions of the improved fuel «green diesel» with bio-additives, and two-component mixtures of environmentally friendly diesel fuel with bio-additives. Using these methods, it is possible to produce fuel for diesel engines with improved lubricating properties, the wear scar diameter is reduced to 232 microns, according to EN 590: 2009, this value standard is up to 460 microns. The optimal quantitative composition of three-component environmentally friendly diesel fuel with improved lubricity was established. The dependence of the change in the lubricating properties of environmentally friendly diesel fuel on the quantitative and qualitative composition are established. A mathematical equation describing the dependence of the change in the corrected wear spot on the amount of anti-wear additive in the green diesel fuel is derived. Three-component compositions of environmentally friendly diesel fuel make it possible to obtain fuel that meets the requirements of the EN 590: 2009 standard and to expand the resources for obtaining fuel, as well as to improve the environmental and operational characteristics of the fuel. Full article