Etherification of glycerol with C 4 and C 5 reactive olefins

Energies, 2019

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.

Applied Catalysis A: General, 2009

The Scientific World Journal

The etherification of glycerol with propylene over acidic heterogeneous catalysts, Amberlyst-15, S100, and S200 resins, produced mono-propyl glycerol ethers (MPGEs), 1,3-di- and 1,2-di-propyl glycerol ethers (DPGEs), and tri-propyl glycerol ether (TPGE). The propylation of glycerol over Amberlyst-15 yielded only TPGE. The glycerol etherification with 1-butene over Amberlyst-15 and S200 resins produced 1-mono-, 2-mono-, 1,2-di-, and 1,3-di-butyl glycerol ethers (1-MBGE, 2-MBGE, 1,2-DBGE, and 1,3-DBGE). The use of Amberlyst-15 resulted in the propylation and butylation of glycerol with higher yields than those obtained from the S100 and S200 resins. The PGEs, TPGE, and BGEs were evaluated as cold flow improvers and octane boosters. These alkyl glycerol ethers can reduce the cloud point of blended palm biodiesels with diesel. They can increase the research octane number and the motor octane number of gasoline.

Bioresource Technology, 2012

The synthesis of oxygenated fuel additives via solvent freebase-catalyzed etherification of glycerol is reported. The products of glycerol etherification arediglycerol (DG) and triglycerol (TG) with DG being the favorable one. The catalytic activity of different homogeneous alkali catalysts (LiOH, NaOH, KOH and Na 2 CO 3) was investigated during the glycerol etherification process. LiOH exhibited an excellent catalytic activity during this reaction, indicated by the complete glycerol conversion with a corresponding selectivity of 33% toward DG. The best reaction conditions were a reaction temperature of 240°C, a catalyst/glycerol mass ratio of 0.02 and a reaction time of 6 h. The influences of various reaction variables such as nature of the catalyst, catalyst loading, reaction time and reaction temperature on glycerol etherification were elucidated. Industrially, the findings attained in this study might contribute towards promoting the biodiesel industry through utilization of its by-products.

Catalysts

The etherification of glycerol with tert-butyl alcohol in the presence of acid catalysts gives rise to the production of ethers (monoethers, diethers and triethers) of high added-value, which can be used as oxygenated additives in fuels. This reaction is limited by the thermodynamic equilibrium, which can be modified by the addition of solvents that selectively solubilize the products of interest along with tert-butyl alcohol, leading to the progress of the reaction. In this work, it has been demonstrated that the addition of dibutyl ether allows shifting the reaction equilibrium, increasing the production of diethers. From the study of the main operating conditions, it was determined that an increase in the concentration of the solvent has a positive effect on the selectivity towards the production of diethers, the concentration of the catalyst (a commercial ion exchange resin, Amberlyst 15, named A-15) and the reaction temperature were also determining variables. Working with conc...

Applied Catalysis A: General, 2010

Etherification of glycerol by isobutylene was conducted in a batch mode using acidic and partially neutralized Amberlyst-15 ionic resin, p-toluenesulfonic acid, silicotungstic acid, cesium salt of silicotungstic acid, and ionic liquid containing sulfonic acid groups. All the catalysts are comparable in terms of the initial rate of glycerol conversion into mono-ether (except cesium salt of heteropolyacid), but differ substantially with respect to the yields of higher ethers of glycerol.

Material Science and Applied Chemistry, 2013

Glycerol ethers could be the good fuel additives. In recent years, the etherification of glycerol has been widely investigated. We tried to perform the synthesis of glycerol ethers using different alcohols-ethanol, isopropanol, tert-butanol. Amberlyst-15, Amberlyst-36, Montmorillonite K 10, β-zeolite were used as catalysts. The etherification reaction between glycerol and alcohols was carried out under atmospheric pressure, by operating at different temperatures ranging from 60 °C to boiling temperatures, at different reaction times and at both different catalyst/glycerol and alcohol/glycerol rates. We also tried to perform this reaction using ultrasonic and microwave conditions. The best results were achieved, when toluene as a solvent and Amberlyst-36 as a catalyst were used.

2011

The present study is focused on the etherification of glycerol with anhydrous ethanol over arenesulfonic acid-functionalized mesostructured silicas to produce ethyl ethers of glycerol that can be used as gasoline or diesel fuel components. Within the studied range, the best conditions to maximize glycerol conversion and yield towards ethyl-glycerols are: T = 200ºC, ethanol/glycerol molar ratio = 15/1, and catalyst loading = 19 wt.%. Under these reaction conditions, 74% glycerol conversion and 42% yield to ethyl ethers have been achieved after 4 h of reaction but with a significant presence of glycerol by-products. In contrast, lower reaction temperatures (T=160ºC) and moderate catalyst loading (14 wt.%) in presence of a high ethanol concentration (ethanol/glycerol molar ratio = 15/1) are necessary to avoid the formation of glycerol by-products and maximize ethyl-glycerols selectivity. Interestingly, a close catalytic performance to that achieved using high purity glycerol has been obtained with low-grade water-containing glycerol.

Korean Journal of Chemical Engineering, 2011

Etherification of glycerol by isobutylene was performed using ion-exchange resin Amberlyst 15, partially neutralized Amberlyst 15 as heterogeneous catalyst, and p-toluenesulfonic acid as a homogeneous catalyst. Amberlyst 15 exhibited strong internal diffusion limitations for the initial composition of reaction mixture. Diffusion limitations decrease in the course of reaction due to the accumulation of mono-ether having excellent solubilizing properties. Oligomerized isobutylene is a dominant by-product for high isobutylene-to-glycerol ratio and long contact time in the case of Amberlyst 15. Density reduction of acidic protons in Amberlyst 15 by partial ion exchange with sodium ions leads to considerable reduction of isobutylene affinity to Amberlyst 15, and as a result, it reduced losses of isobutylene. This partial neutralization leads to lower space-time yields of target products, but enhances selectivity to higher ethers with maintaining conversion of glycerol over 95%.

Central European Journal of Chemistry, 2014

In this work the etherification reaction of glycerol with isobutene (IB) and tert-butyl alcohol (TBA) has been studied with the aim of obtaining mixtures with high content of poly-substituted ethers. The results obtained using solid acid catalysts have shown the reaction with IB proceeds at a high rate but the formation of undesired di-isobutene (DIB) presents a serious problem when catalysts with high density of acid sites, such as Amberlyst, are used. When using TBA as a reactant, the main problem is the formation of water that, due to thermodynamic reasons, which prevents the formation of poly-substituted ethers regardless of the catalyst used. Some preliminary experiments carried out with a water permselective tubular membrane have demonstrated that the yield of poly-substituted ethers significantly increases once water was selectively removed from the reaction medium by recirculation of the gas phase.