Valorization of Solketal Synthesis from Sustainable Biodiesel Derived Glycerol Using Response Surface Methodology

Abstract

Biodiesel production has gained considerable importance over the last few decades due to the increase in fossil fuel prices as well as toxic emissions of oxygen and nitrogen. The production of biodiesel via catalytic transesterification produces crude glycerol as a co-product along with biodiesel, amounting to 10% of the total biodiesel produced. Glycerol has a low value in its impure form, and the purification of glycerol requires sophisticated technologies and is an expensive process. The conversion of crude glycerol into value-added chemicals such as solketal is the best way to improve the sustainability of biodiesel synthesis using the transesterification reaction. Therefore, the conversion of crude glycerol into the solketal was investigated in a batch reactor simulation model developed by the Aspen Plus V11.0. The non-random two liquid theory (NRTL) method was used as a thermodynamic property package to study the effect of four input ketalization parameters. The model was validated with the findings of previous experimental studies of solketal synthesis using sulfuric acid as a catalyst. The influence of the following operating parameters was investigated: reaction time of 10,000 to 60,000 s, reaction temperature of 303 to 323 K, acetone to glycerol molar ratio of 2:1 to 10:1, and catalyst concentration of 0.005 to 0.03 wt %. The optimum solketal yield of 81.36% was obtained at the optimized conditions of 313 K, 9:1, 0.03 wt %, and 40,000 s. The effect of each input parameter on the ketalization process and interaction between input and output parameters was investigated by using the response surface methodology (RSM) optimizer. The relationship between independent and response variables developed by RSM fit most of the simulation data, which showed the accuracy of the model. A second-order differential equation fit the simulation data well and showed an R2 value of 0.99. According to the findings of RSM, the influence of catalyst amount, acetone to glycerol molar ratio, and reaction time were more significant on solketal yield. The effect of temperature on the performance of the reaction was not found to be significant because of the exothermic nature of the process. The findings of this study showed that biodiesel-derived glycerol can be effectively utilized to produce solketal, which can be used for a wider range of applications such as a fuel additive. However, further work is required to enhance the solketal yield by developing new heterogeneous catalysts so that the industrial implementation of its production can be made possible.

Catalysis for Oleochemical Platforms

“…Despite many obvious disadvantages of using such strong acids (product separation, purification workups, corrosion of plants, hazards), laboratory‐scale examples of their use are still present in literature, due to the high activity of these catalysts. Examples are the use of p‐TSA reported in 2011 by Suriyaprapadilok and Kitiyanan [91] and the use of sulfuric acid in 2021 by Arun et al [92] …”

“…(product separation, purification workups, corrosion of plants, hazards), laboratory-scale examples of their use are still present in literature, due to the high activity of these catalysts. Examples are the use of p-TSA reported in 2011 by Suriyaprapadilok and Kitiyanan [91] and the use of sulfuric acid in 2021 by Arun et al [92] To overcome the drawbacks of the use of homogeneous Brønsted acids, heterogeneous catalysts were later preferred. The most used ones were zeolites, sulfonated resins, heteropolyacids, metal oxides.…”

Ultrasonication Assisted Catalytic Transesterification of Ceiba Pentandra (Kapok) Oil Derived Biodiesel Using Immobilized Iron Nanoparticles

“…The negative value of entropy (∆S) indicates that the degree of ordered alignment of the transition state is better as compared to reactant in the ground state. In Figure 7b, the positive value of Gibbs free energy (∆G) indicates that the reaction was unspontaneous and endergonic [57]. The immobilized magnetite catalyst-based Fuels 2022, 3 transesterification reaction of Gibbs free energy and enthalpy are comparatively better than those of the heterogeneous and homogenous catalytic transesterification reaction and only a few works have been reported in the literature [24,27,55].…”

Heteropoly Ionic Liquid Functionalized MOF-Fe: Synthesis, Characterization, and Catalytic Application in Selective Acetalization of Glycerol to Solketal as a Fuel Additive at Room Temperature, Solvent-Free Conditions

“…Furthermore, these energy sources are nonrenewable, and their reserves are depleting. As a result, significant studies have been investigated to explore possible replacements of fossil fuels with biofuels. , This is because biodiesel’s features include being environmentally benign, nontoxicity, lubricity, biodegradability, viscosity, renewability, having a high flash point, etc. − The most common method of producing biodiesel is by the transesterification of vegetable oils, which results in glycerol as a byproduct in huge amounts with environmental issues. , It also affects the economy of biodiesel production . Therefore, many studies have been done to convert glycerol into value-added products through various reactions, including esterification, hydrogenolysis, etherification, oxidation, acetalization, etc.…”

“…39,40 It also affects the economy of biodiesel production. 41 Therefore, many studies have been done to convert glycerol into value-added products through various reactions, including esterification, 42 hydrogenolysis, 43 etherification, 44 oxidation, 45 acetalization, 46 etc. Among different glycerol-derived products, glycerol acetalization efficiently converts glycerol into valuable chemicals.…”