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In this work the etherification reaction of glycerol with isobutene (IB) and tert-butyl alcohol (TBA) has been studied with the aim of preparing mixtures with high content of poly-substituted ethers. The results obtained using solid acid catalysts have shown that the reaction with IB proceeds at a high rate but the formation of undesired di-isobute...
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Citations
... The reaction mixture was heated to 70 • C in 0.5 h, whereas each reaction typically lasted for 7 h at the reaction conditions [12]. A stainless-steel jacketed batch reactor was subjected to a stirring frequency of 1200 min −1 in order to limit the influence of external mass transfer phenomena [55,56]. Fixed bed flow reactor was also used for this reaction in a temperature range of 70 • C to 110 • C [57] with various pressure conditions such as vacuum pressure with continuous removal of water which was formed during the reaction [58], autogenous pressure of 0.5 MPa [15] up to 1.5 MPa [16,59] as well as specified pressure in the range of 2.5 bar at room temperature and upon heating to 80 • C [60] for 40 min which increased the pressure from 12 bar [61] to 20 bar [62]. ...
... The reaction mechanism of glycerol etherification with TBA is shown in Figure 5 [41]. Besides that, the dehydration of TBA to isobutene (IB) is an independent side reaction that not only results in the undesired consumption of glycerol but also produces 3 wt% to 6 wt% of IB in the product mixture, depending on reaction conditions [56,66,[81][82][83][84][85][86][87][88][89][90][91]. The production of isobutene was aided by the concentration of H 3 O + ions in the reaction pathway. ...
... These ions were formed because of the hydrolysis of Sn 2+ cations through water that were produced during the dehydration of alcohol [113,114]. Moreover, the formation of IB will trigger another side reaction, which is the dimerization of isobutene, leading to the formation of di-isobutene (DIB) [56,81,82,84,89]. Several researchers did not observe the formation of DIB in the glycerol etherification process when amorphous organosilica-aluminum phosphates were being utilized [86]. ...
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.
... This result clearly demonstrated that the presence of water makes the formation of h-GTBE difficult, in agreement with Klepàcová et al. [64]. To overcome the problem of the presence of water in the reaction mixture, Cannilla et al. [67,68] employed a water permselective membrane, allowing the equilibrium to be shifted toward the formation of poly-ethers. This membrane selectively removed the water formed by the recirculation of the gas phase. ...
Biodiesel production has considerably increased in recent decades, generating a surplus of crude glycerol, which is the main drawback for the economy of the process. To overcome this, many scientists have directed their efforts to transform glycerol, which has great potential as a platform molecule, into value-added products. A promising option is the preparation of oxygenate additives for fuel, in particular those obtained by the etherification reaction of glycerol with alcohols or olefins, mainly using heterogeneous catalysis. This review collects up-to-date research findings in the etherification of glycerol, either with isobutene (IB) or tert-Butyl alcohol (TBA), highlighting the best catalytic performances reported. Furthermore, the experimental sets employed for these reactions have been included in the present manuscript. Likewise, the characteristics of the glycerol ethers–(bio)fuel blends as well as their performances (e.g., quality of emissions, technical advantages or disadvantages, etc.) have been also compiled and discussed.
... Recently, available Amberlyst-15 has played an important role in organic synthesis. This review summarizes the versatile synthetic applications of Amberlyst-15 in various chemical transformations (Cannilla et al., 2012). The present research work reports the use of Amberlyst-15 resin as an efficient heterogeneous catalyst for the synthesis of OBMF from 5-HMF under mild reaction conditions. ...
... Recently, available Amberlyst-15 has played an important role in organic synthesis. This review summarizes the versatile synthetic applications of Amberlyst-15 in various chemical transformations (Cannilla et al., 2012). The present research work reports the use of Amberlyst-15 resin as an efficient heterogeneous catalyst for the synthesis of OBMF from 5-HMF under mild reaction conditions. ...
... Recently, available Amberlyst-15 has played an important role in organic synthesis. This review summarizes the versatile synthetic applications of Amberlyst-15 in various chemical transformations (Cannilla et al., 2012). The present research work reports the use of Amberlyst-15 resin as an efficient heterogeneous catalyst for the synthesis of OBMF from 5-HMF under mild reaction conditions. ...
An ultrasonic-assisted method to obtain 5,5 (oxy-bis(methylene))bis-2-furfural a prepolymer and an antiviral precursor was presented in the present paper. Amberlyst-15 was used as an efficient and recy-clable heterogeneous catalyst to realize the etherification of 5-hydroxymethylfurfural. The crucial role of ultrasound in terms of improving the time and catalyst efficiency, reaction yield was also discussed.
The increase in biodiesel production has resulted in the oversupply of glycerol into the market. Purified and processed glycerol has found many direct applications in pharmaceuticals, food, etc. However, the cost of processing and market value of processed glycerol has driven the research of direct utilization of crude glycerol to industrially essential chemicals. Various methods and research have been devoted to using glycerol to produce value-added products separately. Glycerol can undergo several transformation reactions like hydrogenation, oxidation, alcoholysis, and etherification. Etherification of glycerol can be divided into three main reactions: self-etherification, using alcohol, and olefins and these products have vast applications such as fuel additives, plasticizer, etc. The current review presents a comprehensive summary of glycerol etherification to value-added products and their applications. The catalytic system developed along with reaction conditions and the factors responsible for the better activity is also discussed. Overall, the review presents a detailed discussion on the catalytic system developed, the utilization of different alcohols and olefins, and the application of products. Moreover, the environmental and economic aspects of the etherification of glycerol via various conversion routes while assessing the process parameters needs to be tackled to attain wider adoption of the process.
In this work, phosphomolybdic acid salts were synthesized exchanging their protons by the Sn(II) cations (i.e., H3-xSnx/2PMo12O40; x = 0.0, 1.0, 2.0, 3.0), and evaluated in the etherification reactions of glycerol with tert-butyl alcohol (TBA). The catalytic activity of the phosphomolybdate salts containing a variable load of Sn(II) ions was further compared to phosphotungstic and silicotungstic acid salts (i.e., H3-xSnx/2PW12O40; x = 0.0, 1.0, 2.0, 3.0 and H4-xSnx/2PW12O40; x = 0.0, 1.0, 2.0, 4.0, respectively). The integrity of the Keggin anion after the synthesis was confirmed by infrared spectroscopy analysis. Physical properties were determined through thermal analyses, powder X-Rays diffraction patterns, N2 adsorption-desorption isotherms, and scanning electron microscopy. The acidity properties were analyzed by adsorbed pyridine FT-IR spectroscopy, NH3-programmed-temperature desorption, and potentiometric titration. Among all the Sn(II) heteropoly salts tested, the Sn3PMo12O40 was the most active and selective catalyst toward glyceryl ethers. The highest activity of Sn3PMo12O40 was assigned to the greater Lewis acidity strength. Modeling, simulation, and economic analysis allowed to evaluate the viability of the process. An annual capacity of 30,000 metric tons was developed, and the process is feasible with a return on investment (ROI) of 30.7%.
A preliminary evaluation of the techno-economic feasibility of an industrial glycerol etherification process for bio-additives production has been carried out. The attention has been focused on the etherification reaction in presence of isobutylene (IB) or tert-butanol (TBA) in a batch reactor, catalyzed by an optimized heterogeneous system. Specifically, the Hyflon-based catalyst resulted more efficient and selective to desired products than commercial resin, limiting the competitive reactions of IB oligomerization and byproduct formation. In case of IB, a mixture of poly-ethers, suitable as oxygenated additives for diesel engines, containing very low amount of mono-tert-butylethers (<2 wt%) was obtained in a single step. This allowed a simplification of the process without the need of separation units and a lower production cost with respect to other reference processes. When TBA was used and water was formed as byproduct, a permeoselective membrane was exploited improving the glycerol conversion and enhancing the poly-ethers productivity by continuous water removal. In fact, very high poly-ethers yield (>85%) was achieved under optimized reaction conditions. The analysis of the whole process demonstrated the techno-economic sustainability of the proposed routes, leading to a production price of glycerol poly-ethers of 1,14 USD/kg and 2,38 USD/kg, by using IB or TBA respectively.
In this work, efficient solid acid catalysts were obtained from the stoichiometric reactions of Keggin heteropolyacids with SnSO4 and evaluated in the etherification reactions of glycerol with tert-butyl alcohol (TBA). Among the salts synthesized, the Sn2SiW12O40 catalyst was the most active and selective toward glyceryl ethers. High yields of mono and di glyceryl tert-butyl ethers were achieved after 4 h of reaction at 393 K. The impacts of the main reaction parameters such as stoichiometry of the reactants, catalyst load, time and reaction temperature were assessed. The efficiency of the Sn2SiW12O40 catalyst was also assessed in etherification reactions of ethylene glycol with TBA, and etherification reactions of glycerol with other alcohols (i.e., n- or sec butyl alcohol, and n- or isopropyl alcohol). A proposal that describes the reaction pathway including the catalyst participation was also described. The Sn2SiW12O40 catalyst was easily recovered and reused without loss activity.
