Transesterification Of Glycerol Research Articles

Upgrading of glycerol from biodiesel synthesis with dimethyl carbonate on reusable Sr–Al mixed oxide catalysts

The high demand for renewable energy has led to the upsurge of methanol-assisted biodiesel synthesis. Therefore, glycerol as a byproduct entered the waste stream given the oversupply of biodiesel to the market. The dimethyl carbonate (DMC)-assisted transesterification of glycerol on a catalyst has been a popular approach for converting glycerol into valuable glycerol carbonate (GLC). The synthesis of GLC from the DMC-assisted transesterification of glycerol on mixed oxide catalysts (Srx–Al) with different Sr/Al ratios was examined in this study. A glycerol conversion of 99.4% and a GLC yield of 100% were achieved in a catalyst with Sr/Al=0.5 (Sr0.5–Al). Both values are higher than those in catalysts synthesized with Sr/Al=0.25 and 0.75. The Sr0.5–Al catalyst withstood five transesterification reaction cycles without a serious deactivation induced by the leaching of active SrO. Therefore, the Sr0.5–Al catalyst is suitable for consecutive uses in the DMC-assisted transesterification of glycerol with DMC into GLC.

CaO催化非均相体系制备碳酸甘油酯

以CaO为催化剂，将其用于催化甘油与碳酸二甲酯酯交换反应制备碳酸甘油酯，考察了CaO预处理条件和反应条件对碳酸甘油酯产率的影响。实验结果表明：催化剂焙烧温度对碳酸甘油酯产率影响显著，800℃焙烧的CaO具有较高的催化活性。在反应温度65℃，甘油与碳酸二甲酯摩尔比1:3，催化剂用量5%(基于甘油质量)条件下，CaO催化反应1 h碳酸甘油酯产率可达87.02%。 CaO was applied to glycerol carbonate production by the transesterification of glycerol and dimethyl carbonate. The effects of the catalyst preparation conditions and reactions condition on the performances of CaO in the transesterification were investigated. The results showed that the catalyst activity of CaO was greatly influenced by the different calcination temperatures, and the catalyst possesses a good activity when it was calcined at the temperature 800˚C. A desired glycerol carbonate yield of 87.02% was obtained at glycerol/dimethyl carbonate of 1:3, catalyst amount of 5%, and reaction time of 1 h at 65˚C.

Tandem Synthesis of Glycidol via Transesterification of Glycerol with DMC over Ba-Mixed Metal Oxide Catalysts

Glycerol carbonate (GC) and glycidol (GD) are commercial products possible from glycerol transformation, which has become a subject of great importance. Among several basic catalysts screened in this work, BaO showed the highest glycerol conversion of 71% with almost complete selectivity to GC. A tandem synthesis of GD with a selectivity as high as 80% with 98% glycerol conversion could be achieved with mixed oxides of Ba and lanthanides (La and Ce) prepared by the coprecipitation method. Although BaO alone showed the highest basicity as measured by CO2 TPD, tuning of basicity by incorporation of CeO2 resulted in the formation of GD. Incorporation of Ba into the ceria matrix induced oxygen vacancies in the cerium oxide material. The presence of u″/v″ doublets at 888.7 and 903.2 eV, respectively, in XPS of the Ba–Ce sample also confirmed the oxygen vacancies in the lattice. In this tandem approach to GD, the subsequent decarboxylation of initially formed GC was due to the presence of a CeO2 lattice with de...

High-efficiency and low-cost Li/ZnO catalysts for synthesis of glycerol carbonate from glycerol transesterification: The role of Li and ZnO interaction

A series of efficient and low-cost Li/ZnO catalysts were prepared by a simple impregnation method and investigated for the synthesis of glycerol carbonate (GC) from the transesterification of glycerol with dimethyl carbonate (DMC). The Li/ZnO catalysts were characterized using XRD, SEM, FT-IR, TG-DSC, TPD and XPS. It was found that the basicity of the catalysts highly depended on the Li loading and calcination temperature. The weak and moderate basic sites on the catalyst surfaces originated from the ZnO and Li+ interaction. The strong basic sites were attributed to the substitution of Zn2+ by Li+ in the ZnO lattice, which led to straining of Zn-O bonds and the formation of [Li+ O−] species. It was the strong basic sites rather than the weak and moderate basic sites that catalyzed the transesterification of glycerol with DMC. The highest catalytic activity was observed over the ZnO loaded with 1wt.% LiNO3 and calcined at 500°C. Glycerol conversion of 97.40% and GC yield of 95.84% were obtained over this catalyst at 95°C in 4h.

Stabilized ladle furnace steel slag for glycerol carbonate synthesis via glycerol transesterification reaction with dimethyl carbonate

Abundant waste from ladle furnace (LF) steel slag industry was utilized to catalyze the glycerol transesterification reaction with dimethyl carbonate (DMC) to synthesize valuable glycerol carbonate (GC). LF slag was modified using various sodium hydroxide (NaOH) loadings (1–15wt.%), and the catalyst samples were characterized using XRD, FTIR, TPD-CO2, and EDS techniques. Modifying the LF using different NaOH loadings enhanced the stability, basicity, and basic strength of LF. Favorable reaction conditions at the best glycerol conversion and GC yield were investigated via reaction influencing parameter screening. Thus, the 10wt.% NaOH incorporated in LF under the reaction conditions of 75°C, DMC-to-glycerol molar ratio of 2, and 3wt.% catalyst dosage achieved 99% glycerol conversion and 97% GC yield. The catalyst exhibited sufficient heterogeneity and was utilized in five successive cycles of the experiment without serious deactivation.

Synthesis of glycerol carbonate from biodiesel by-product glycerol over calcined dolomite

Abstract Glycerol, which threatens the viability of biodiesel industries, can be converted to valuable chemicals and chemical intermediates, such as glycerol carbonate (GC). GC was synthesized by glycerol transesterification with dimethyl carbonate (DMC) on CaO–MgO mixed oxide catalyst prepared from natural dolomite. At calcination temperature of 800 °C, natural dolomite was converted to CaO–MgO mixed oxide to serve as catalyst in the conversion of glycerol to GC. Temperature changes and calcined dolomite surface and textural characteristics caused the glycerol transesterification with DMC to GC. The catalyst with 15

Thermal (Catalyst-Free) Transesterification of Diols and Glycerol with Dimethyl Carbonate: A Flexible Reaction for Batch and Continuous-Flow Applications

An innovative thermal transesterification protocol for the synthesis of linear and alkylene carbonates was investigated under both batch and continuous-flow (CF) conditions. Accordingly, model 1,n-diols (n = 2–4) and glycerol were set to react with dimethyl carbonate (DMC) at T and p of 150–260 °C and 1–50 bar, respectively, in the absence of any catalyst. 1,2-diols afforded the corresponding five-membered ring carbonates as the main products with a quantitative conversion and a selectivity up to 94%, whereas 1,3-diols gave the six-membered ring products along with linear mono- and dicarbonate derivatives. A complete conversion was attained also for glycerol, but the products distribution depended on reaction conditions: the CF mode allowed the synthesis of glycerol carbonate, whereas batch reactions yielded either glycerol carbonate or its derivative from a further transesterification reaction, i.e., methyl (2-oxo-1,3-dioxolan-4-yl)methyl carbonate. The selectivity toward these two compounds was in the range of 83%–94%. An addition of gaseous CO2 (up to 20 bar) allowed to control further the selectivity of batch reactions.

A Novel Process for the Synthesis of Highly Pure n-3 Polyunsaturated Fatty Acid (PUFA)-Enriched Triglycerides by Combined Transesterification and Ethanolysis

In this study, a novel two-step enzymatic reaction was developed for the synthesis of highly pure triacylglycerols (TAGs) with a high content of n-3 polyunsaturated fatty acids (PUFAs). Glyceride mixtures were primarily synthesized by Novozym 435-catalyzed transesterification of glycerol and DHA/EPA-rich ethyl esters (EEs), followed by removal of partial glycerides, for the first time, by immobilized mono- and diacylglycerol lipase SMG1-F278N-catalyzed ethanolysis. TAG yield as high as 98.66% was achieved under the optimized conditions, and highly pure (98.75%) n-3 PUFA-enriched TAGs with 88.44% of n-3 PUFA was obtained after molecular distillation at lower temperature (140 °C). In addition, the EEs produced during ethanolysis had a FA composition similar to that of the original EEs, making them feasible for cyclic utilization. This was the first study reporting removal of partial glycerides by ethanolysis. Through ethanolysis, a higher purity product could be easily obtained at a relatively low temperature compared with the conventional high-temperature molecular distillation.

CaAl-layered double hydroxides as active catalysts for the transesterification of glycerol to glycerol carbonate

Several hydrocalumite-type materials (CaAl-LDHs) were prepared by precipitation using nitrate or chloride salts with and without ultrasound, and aged hydrothermally in autoclave or by refluxing with and without microwaves. These samples were tested as catalysts for the transesterification of glycerol with dimethyl carbonate to glycerol carbonate. After 3h of reaction, all catalysts showed high glycerol conversion (70–84%) and moderate selectivity values to glycerol carbonate (52–65%) accompanied by the formation of low amounts of glycidol (7–15%). These results are very interesting taking into account the low specific surface area of these catalysts (7–25m2/g). No significant catalytic differences were observed between the catalysts. This can be due to the similar surface and basic characteristics observed for all of them. By increasing the reaction time, an increase of conversion was observed arriving practically to total conversion after 24h of reaction, with selectivity to glycerol carbonate in the range 65–75%. Several catalytic reuses favoured the decarboxylation of glycerol carbonate resulting in the formation of higher amounts of glycidol (30%) but still maintaining high selectivity values to glycerol carbonate (70%).

Glycerol Carbonate Synthesis by Hierarchically Structured Catalysts: Catalytic Activity and Characterization

The surge in biodiesel production in recent years has resulted in enhanced research interest in the conversion of glycerol to other valuable chemicals such as glycerol carbonate (GLC). In the present study, the catalytic transesterification of glycerol with dimethyl carbonate (DMC) for the production of GLC was studied with calcium–lanthanum mixed-oxide catalysts at different Ca/La molar ratios. These catalysts were synthesized using an exo- and endotemplating method. The physicochemical characteristics of the catalysts were determined using powder X-ray diffraction (XRD), N2 sorption, scanning electron microscopy (SEM), and temperature-programmed desorption (TPD) of CO2 and NH3. The transesterification of glycerol was found to be highly dependent on the basicity of the catalysts. The catalyst with a Ca/La molar ratio of 3 (3CaLa) showed the highest glycerol conversion and GLC yield. Optimization of the reaction parameters and reusability of the catalyst were studied with the 3CaLa catalyst in terms of gl...

Transesterification of glycerol with dimethyl carbonate over calcined Ca-Al hydrocalumite

A series of Ca-Al hydrocalumite with different Ca/Al ratios (1–6) were synthesized and used in the transesterification of glycerol with dimethyl carbonate (DMC) to glycerol carbonate (GC) under mild conditions. The calcined Ca-Al hydrocalumites were active with a selectivity toward GC that reached 97% at 93% conversion of glycerol over the sample with Ca/Al = 2 at 70 °C, 3 h, and DMC/glycerol = 3. The glycerol conversion depended mainly on the proportion of strong basic sites in the calcined Ca-Al catalysts. The Ca12Al14O33 phase in the calcined catalysts was stable, but CaO was lost in recycle experiments and thus brought deactivation.

Transesterification of glycerol with dimethyl carbonate over nanocrystalline ordered mesoporous MgO–ZrO2 solid base catalyst

One-pot nanocrystalline mesoporous MgO- ZrO2 solid solution was synthesised by a simple evapora- tion induced self assembly route with ZrO(NO3)28H2O and Mg(NO3)24H2O as precursors along with triblock co- polymer of Pluronic P123 as structure directing agent. The prepared catalysts were characterised by X-ray diffraction studies (XRD), N2 adsorption/desorption isotherms, Four- ier transform infrared spectroscopy, TPD of CO2 and transmission electron microscopy (TEM). XRD results confirm the formation of nanocrystalline ordered meso- porous structure of MgO-ZrO2 (MZx). Additionally the TEM and N2 sorption study confirms the ordered meso- porous nature of MZx materials. The Mg 2? incorporation into zirconia lattice presumably stabilizes the tetragonal phase and avoids excessive growth of zirconia crystals. The activity of the prepared samples was tested for the trans- esterification of glycerol. Among all tested, the MZ2 cat- alyst (Mg:Zr ratio 1:2) proved to be efficient for the transesterification of glycerol by dimethyl carbonate (96 % conversion and 88 % yield). We attribute the high effi- ciency of MZ2 to its basic nature and highly dispersed MgO species.

Microwave-assisted transesterification of industrial grade crude glycerol for the production of glycerol carbonate

This study is the first of its kind to report on the transesterification of industrial grade crude glycerol (GLY) to glycerol carbonate (GC) using microwave processing. Pure and two grades of crude GLY at 70% and 86% purity were transesterified with dimethyl carbonate (DMC) using calcium oxide (CaO) as catalyst. A comparison study was made of the conventional and microwave-assisted transesterification process. It was found that 70% purity of crude GLY gave higher yield in both conventional and microwave-assisted transesterification processes with the latter technique showing better energy efficiency. The highest GC yield of 93.4% was obtained from GLY with purity of 70% under microwave irradiation system with 1wt% of catalyst, 2:1M ratio of DMC:GLY at 65°C in five minutes reaction time. The yield of GC was observed to increase with temperature, time and molar ratio but not the catalyst loading. The impurities such as methanol (MeOH) and sodium methylate (NaOMe) in the crude GLY were found to increase GC yield by four times. This indicates that the impurities which might not be desirable for the transesterification process under normal circumstances have unconventionally demonstrated positive effects on the performance of transesterification under microwave irradiation.

Microwave Assisted Solvent-Free Catalytic Transesterification of Glycerol to Glycerol Carbonate

Microwave Assisted Solvent-Free Catalytic Transesterification of Glycerol to Glycerol Carbonate

Production of glycerol carbonate via reactive distillation and extractive distillation: An experimental study

A process for the production of glycerol carbonate (GC) is proposed with the transesterification of glycerol (GL) and dimethyl carbonate (DMC) with CaO as catalyst by reactive distillation and extractive distillation. The performance of solvents in separating DMC-methanol azeotrope and the effects of operation parameters on the reactive distillation process are investigated experimentally. The results indicate that both the GL conversion and GC yield increase with the DMC/GL molar ratio, reflux ratio, final temperature of tower bottom, and CaO/GL molar ratio and decrease as the recycle number of CaO increases. The calcium concentration in the residual reaction mixture also decreases remarkably as the DMC/GL molar ratio increases. At DMC/GL molar ratio 4.0, reflux ratio 1.0, final temperature of tower bottom 358K, and CaO/GL molar ratio 0.05, both the GL conversion and GC yield can reach above 99.0%, and the mass concentration of calcium in the product is less than 0.08%.

Kinetics of the production of glycerol carbonate by transesterification of glycerol with dimethyl and ethylene carbonate using potassium methoxide, a highly active catalyst

The biodiesel industry has been dealing with the issue of glycerol oversupply for some time, leading to blossoming research regarding its valorisation to yield value-added derivatives. This work presents the production of glycerol carbonate through the transesterification of glycerol with dimethyl carbonate (DMC) and ethylene carbonate (EC), also obtaining valuable methanol and ethylene glycol, respectively. CH3OK was used as catalyst, with kinetic runs being conducted under mild operation conditions: temperature (50–70°C using DMC; 40–60°C using EC), molar excess of organic carbonate to glycerol (1.5–3) and low catalyst loads (1000–2500ppm for DMC; 50–150ppm for EC). Kinetic models were proposed, fitted and verified considering the transition from a biphasic to a single phase liquid system and a first order deactivation of the catalyst. In the reaction with DMC, the model contemplates an irreversible reaction with activation energy of 28.4±1.5kJ·mol−1 and deactivation constant of 0.03±0.01min−1. Using EC, the activation energies were 83.0±1.6kJ·mol−1 and 58.7±11.4kJ·mol−1 for the direct and reverse reactions, respectively, and the deactivation constant was 0.11±0.02min−1. This catalyst demonstrates a much higher activity for these reactions than K2CO3.

Synthesis of Glycerol Carbonate by Transesterification of Glycerol with Urea Over Zn/Al Mixed Oxide.

Reactions of glycerol carbonate using glycerol and urea have been carried out previously using ZnSO4 and ZnO catalysts, and high yields have been reported using ZnSO4 as catalyst. However, this salt is soluble in glycerol, and recycling of catalyst is difficult after the reaction. In this study, we prepared a mixed metal oxide catalyst using Zn and Al, and this catalyst consisted of a mixture of ZnO and ZnAl2O4. We confirmed the conversion of glycerol and the yield of glycerol carbonate of the amount of Al. As a result, we obtained a yield of 82.3% and a conversion of 82.7%. In addition we obtained high yield in recycling of catalyst. The yield of the glycerol carbonate increases with an increase of acid and base site of catalysts and the highest catalytic activity was obtained when acid/base ratio was approx. 1. From this result, we may conclude that the acid and base site density and ratio of catalysts were very important parameters in the synthesis of glycerol carbonate from urea and glycerol.

Ordered mesoporous BaCO3/C-catalyzed synthesis of glycerol carbonate from glycerol and dimethyl carbonate

BaCO3/C composites were synthesized by a multi-component co-assembly method combined with a carbonization process using phenolic resol as carbon source, barium nitrate as barium precursor, and triblock copolymer Pluronic F127 as template. The synthesized materials were characterized by X-ray diffraction, transmission electron microscopy, N2 physical adsorption, thermogravimetric analysis, and temperature-programmed desorption of CO2. When BaCO3 contents were increased from 9.1 wt% to 44.7 wt%, pore size increased from 3.1 to 4.3 nm and the BET (Brunauer-Emmett-Teller) surface area initially increased to a maximum value of 390 m2 g−1 (at a BaCO3 content of 18.5 wt%) before subsequently decreasing. BaCO3 was well dispersed in the amorphous carbon framework, and no phase separation was observed. The mesoporous Ba-CO3/C composites exhibited high catalytic activities toward the transesterification of glycerol and dimethyl carbonate into glycerol carbonate. A glycerol conversion of 97.8% and a glycerol carbonate selectivity of 98.5% were obtained under the optimized reaction conditions.

One-pot synthesis of glycidol from glycerol and dimethyl carbonate over KF/sepiolite catalyst

Abundantly available natural material, sepiolite was used in combination with KF to develop a transesterification catalyst and used to synthesize glycidol from glycerol and dimethyl carbonate (DMC) in a one step reaction. The composition of the sepiolite determined by X-ray florescence (XRF) makes it a unique candidate for transesterification of glycerol as most of its components have previously been used either in combinations or singly as catalyst for transesterification reactions. Other characterizations of the developed 30%KF/sepiolite catalyst were done by XRD, BET, and FTIR. The optimum reaction conditions of the KF/sepiolite catalyst on transesterification of glycerol with DMC were obtained at 85°C reaction temperature, 2:1 DMC/glycerol, 4% by weight catalyst loading and 90min reaction time. The developed catalyst can be reused up to four cycles with a minimal reduction in its efficiency in transesterification activities.

A review on the performance of glycerol carbonate production via catalytic transesterification: Effects of influencing parameters

Driven by high energy demand and environmental concerns, biodiesel as a substitute for fossil fuels is recognized to be promising renewable and clean energy. The increase in the biodiesel plant dramatically leads to the oversupply of its by-product glycerol in the biodiesel industries. Developing new industrial uses for glycerol is essential to increase the net energy and sustainability of biodiesel. Moreover, glycerol has great potential to be converted into marketable and valuable chemicals. The conversion of glycerol to glycerol carbonate (GC) has been extensively studied and transesterification of glycerol to GC has been proven to be the most promising route. Aimed to reveal the underlying mechanism of this successful conversion path, this paper reviews the chemo- and biocatalytic transesterification of glycerol with different carbonates sources. Also, a detail elucidation of the influence of the catalysts and operating conditions on the GC yield is included to provide an insight into the process. In addition, the future direction of glycerol carbonate production via catalytic transesterification is provided in this review.