Transesterification Of Dimethyl Carbonate Research Articles

Transesterification of Dimethyl Carbonate with Ethanol Catalyzed by Guanidine: A Theoretical Analysis.

Density-functional theory (DFT) was performed to investigate the mechanistic features of different guanidine-based catalysts, namely, 1,1,3,3-tetramethyl guanidine (TMG) and 1,5,7-triaza-bicyclo-[4.4.0]dec-5-ene (TBD), for the transesterification reaction of dimethyl carbonate (DMC) with ethanol (EtOH). Different possible pathways were suggested in which these catalysts act as either nucleophile or base within a homogeneous system. The DFT results allowed not only the study of the thermochemistry aspects of all elementary reactions featured in the two different activation modes but also the accurate calculation of the free energy barriers for each case. Our findings showed that the catalyzed reaction proceeded through simultaneous activation of DMC and EtOH, facilitated by hydrogen bonding for both catalysts. This feature led to the formation of a stable intermediate with a relatively low free energy barrier. TBD exhibited a potentially more efficient mechanism, owing to its planar structure and dual-activation mode. The free energy barrier of the rate-limiting step, identified as the formation of a zwitterionic complex, then declined by approximately 50% when compared with the reaction without catalysts. Overall, the DFT approach provides good insight into the reactivity of both catalysts and helps to find possibilities for further enhancing the mechanistic features of both catalysts for this type of transesterification reaction.

Fine-Tuning Electron-Donor Capability in the Basic Anion of Poly(ionic liquid) Frameworks for Revolutionizing Catalytic Synthesis of Ethyl Methyl Carbonate with Both Ultrahigh Catalytic Activity and Selectivity.

Ethyl methyl carbonate (EMC) is a crucial solvent extensively utilized in lithium-ion battery electrolytes; the transesterification of dimethyl carbonate (DMC) with ethanol is a pivotal reaction for EMC production. However, this reaction faces challenges due to the trade-off between catalytic activity and selectivity from the basic catalysts. In this issue, we report an innovative strategy through fine-tuning the electron-donor capability of the basic phenolate anion ([PhO]) in a novel poly(ionic liquid) (PIL) framework, as synthesized via an alkylation reaction between 1,3,5-tris(bromomethyl)benzene, biphenyldiimidazole, and N,N'-carbonyldiimidazole (CDI) to trigger targeted basicity that can directionally catalyze the transesterification of DMC with ethanol, so as to achieve both ultrahigh catalytic activity and selectivity toward EMC. By varying the substituent groups with electron-withdrawing and electron-donating effects on the phenolate anion, the PILs show expected changes in the catalytic performance, following well with the trend of charge density on these substituted phenolate anions. The optimized catalyst [CPIL-CDI][MeOPhO], induced by p-methoxyphenolate anions, allows an extraordinary EMC yield of 72.19% and an EMC selectivity of 91.48% under mild conditions without any process intensifications, suppressing all of the reported catalysts reported to date. Outcomes and approaches shown in this work have the potential to expedite the systematic design of cations and anions within PILs for industrial-scale EMC production through environmentally friendly transesterification processes.

Kinetics of bis(2‐methyl) butylene carbonate by transesterification of dimethyl carbonate with 1,4‐butanediol

AbstractThe kinetic behavior of bis(2‐methyl) butylene carbonate (BMBC) by the transesterification of dimethyl carbonate (DMC) with 1,4‐butanediol (BDO) was investigated experimentally and theoretically. The Fourier transform infrared spectroscopy (FTIRs) test confirmed that the BMBC was successfully synthesized. The optimum preparation process of BMBC was investigated at atmospheric pressure, where Zn(Ac)2∙2H2O was the best catalyst for this transesterification reaction, and the optimal concentration was 0.3 wt%. The conversion was determined by measuring the amount of methanol produced during the reaction by refractometric method. A kinetic model was proposed according to the experimental results. The results showed that the transesterification reaction was a pseudo‐first‐order reaction. The apparent activation energy (Ea) significantly decreased with the increase of catalyst concentration from 0.1 wt% to 0.5 wt%. The Ea of the reaction was 102.13, 84.36, and 70.18 kJ mol−1, respectively, when the catalyst concentration was 0.1 wt%, 0.3 wt%, and 0.5 wt%. Furthermore, the parameters of the optimal heating curve in the batch reactor was obtained according to the optimal model.

Kinetics measurement of ethylene-carbonate synthesis via a fast transesterification by microreactors

High-purity ethylene carbonate (EC) is widely used as battery electrolyte, polycarbonate monomer, organic intermediate, and so on. An economical and sustainable route to synthesize high-purity ethylene carbonate (EC) via the transesterification of dimethyl carbonate (DMC) with ethylene glycol (EG) is provided in this work. However, this reaction is so fast that the reaction kinetics, which is essential for the industrial design, is hard to get by the traditional measuring method. In this work, an easy-to-assemble microreactor was used to precisely determine the reaction kinetics for the fast transesterification of DMC with EG using sodium methoxide as catalyst. The effects of flow rate, microreactor diameter, catalyst concentration, reaction temperature, and reactant molar ratio were investigated. An activity-based pseudo-homogeneous kinetic model, which considered the non-ideal properties of reaction system, was established to describe the transesterification of DMC with EG. Detailed kinetics data were collected in the first 5 min. Using these data, the parameters of the kinetic model were correlated with the maximum average error of 11.19%. Using this kinetic model, the kinetic data at different catalyst concentrations and reactant molar ratios were predicted with the maximum average error of 13.68%, suggesting its satisfactory prediction performance.

Study on MoO3/SBA-16 catalyzed transesterification to synthesize diphenyl carbonate.

In this paper, the mesoporous molecular sieve SBA-16 with good dispersion was prepared by hydrothermal method. Under the condition of Si/Mo= 1.0, MoO3/SBA-16 catalysts were prepared by iso-dipping method at 550 °C, 650 °C and 750 °C calcination temperature, which for the synthesis of diphenyl carbonate (DPC) from dimethyl carbonate (DMC) and phenyl acetate (PA) was used, and the uncalcined MoO3/SBA-16 was used as a reference. XRD, TG-DTA, XPS, ICP-MS, FT-IR, BET, SEM and TEM characterization. The effects of calcination temperature and reaction conditions on the catalytic performance of MoO3/SBA-16 in transesterification of DMC and PA were investigated. The results show that the MoO3/SBA-16 catalyst prepared at 550 °C has the best catalytic performance in the reaction of DMC and PA ester exchange, and the catalyst has the best catalytic performance in the appropriate reaction strip (n(PA) = 1.0 mol; n (PA)/n (DMC) = 2.0; m (MoO3/SBA-16) = 6.0g; t = 5.0 h; T = 180 °C), the DMC conversion is 78.5%, and the selectivity of methyl phenyl carbonate (MPC) and DPC is 51.1% and 46.5%, respectively. After five cycles, the catalyst activity decreased and the conversion of DMC decreased from 78.5% to 15.8%. However, its crystal structure remained unchanged. The used catalyst can be easily regenerated by calcination in air at 550 °C for 5 h. The catalytic performance of the regenerated catalyst was almost as high as that of the fresh one.

β-Cyclodextrin-Calcium Complex Intercalated Hydrotalcites as Efficient Catalyst for Transesterification of Glycerol

β-cyclodextrin derivative intercalated MgAl-hydrotalcites (β-CD-Ca/LDH) was synthesized to convert glycerol into high value-added glycerol carbonate(GC) by transesterification of dimethyl carbonate (DMC) and glycerol in this paper. β-cyclodextrin-metal complexes and β-CD-Ca/LDH was characterized by XRD, FT-IR, SEM, XPS and nitrogen adsorption-desorption. The enrichment of organic reactants in the hydrophobic cavity of β-cyclodextrin improved the collision probability of reactants. The intercalation of β-cyclodextrin-calcium complex (β-CD-Ca) increased the pore size and basic strength of catalyst. The experiment results showed that the glycerol conversion was 93.7% and the GC yield was 91.8% catalyzed by β-CD-Ca/LDH when the molar ratio of DMC and glycerol was 3:1, the catalyst dosage was 4 wt.%, the reaction temperature was 75 °C and the reaction time was 100 min while the glycerol conversion was 49.4% and the GC yield was 48.6% catalyzed by MgAl-LDH under the same conditions.

Transesterification of dimethyl carbonate with glycerol by perovskite-based mixed metal oxide nanoparticles for the atom-efficient production of glycerol carbonate

The catalytic transesterification of glycerol with dimethyl carbonate (DMC) is an attractive process for the valorization of glycerol, an abundant waste product of the biodiesel industry, by its transformation in industrially attractive glycerol carbonate (GC). Interestingly, perovskites and perovskite-based mixed metal oxides (PBMMOs) were, thus far, only marginally explored for the latter reaction. In this work, a series of PBMMOs were prepared using the non-hydrolytic sol gel (NHSG) methodology as an approach to easily afford nanosized and non-aggregated ternary oxides without calcination steps. The prepared materials were characterized via TEM and SEM microscopies, XRD analysis, XPS, BET surface area and TPD measurements showing that the as-synthesized PBMMOs displayed higher surface areas and larger number of crucial strong basic sites than their analogues produced by calcination at 1000 °C. The catalytic activity of as-synthesized or calcined PBMMOs followed a clear linear trend as a function of the materials basicity with the most basic PBMMOs (SrTiO3-200, YNbO4-200 and BaCeO3-200) performing as the most active catalysts. Selected materials on the basis of catalytic performance and low metal toxicity (SrTiO3-200, YNbO4-200) were subsequently applied to improve the atom economy of the transesterification reaction using low (1:2 or 1:1.5) DMC/glycerol ratios and even equimolar amounts of reagents. Under optimized conditions, the use of SrTiO3-200 as the catalyst allowed the quantitative and selective conversion of glycerol to GC by using 1:2 DMC/glycerol ratio and could be efficiently recycled maintaining at least 95% GC yield at the fifth catalytic run. Albeit slightly less active than SrTiO3-200, YNbO4-200 performed well when working with equimolar DMC/glycerol ratio allowing glycerol conversion and GC yield over 80%.

Rapid Synthesis of Asymmetric Methyl-Alkyl Carbonates Catalyzed by α-KMgPO4 in a Sealed-Vessel Reactor Monowave 50

Dimethyl-carbonate (DMC) is a green carboxymethylation agent for synthesis of the versatile long-chain alkyl carbonates through base-catalyzed transesterification with aliphatic alcohols. Herein, we demonstrated the facile preparation of a novel heterogeneous base catalyst α-KMgPO4 using commercially cheap metal salts via hydrothermal-calcination procedure. The combination of temperature programmed desorption (TPD) and FTIR measurements with CO2 pre-adsorbed revealed the presence of weak and medium base sites on α-KMgPO4. Furthermore, α-KMgPO4 catalyzed transesterification of DMC and n-octanol was performed in a sealed-vessel reactor (Monowave 50). The results show that the reaction was completed in only 10 min with the 97.5% conversion of n-octanol and >99% selectivity to asymmetric methyl-octyl carbonate under the optimal conditions. Additionally, the possible catalytic mechanism is proposed. As an extended contribution, the tribology performance of the asymmetric methyl-alkyl carbonates was further evaluated.

Microwave assisted rapid synthesis of glycerol carbonate from glycerol catalyzed by anhydrous sodium silicate

Glycerol carbonate, a value-added derivative of biomass glycerol, has been synthesized by the transesterification of dimethyl carbonate with glycerol using anhydrous sodium silicate (Na2SiO3) as highly efficient, green and available solid base catalyst. The yield of glycerol carbonate reached up to 93% in 10 minutes under microwave irradiation. The result of leaching test indicated Na2SiO3 was a well-defined heterogeneous catalyst for the reaction. In addition, Na2SiO3 could be reused in 4 runs without significant loss of its catalytic activity.

Synthesis of hydrotalcite-type mixed oxide catalysts from waste steel slag for transesterification of glycerol and dimethyl carbonate

The mixed metal oxides S-CaMgAl MO prepared by acidolysis, coprecipitation and calcination under different temperatures from S95 steel slag of Shanghai Baosteel Co., Ltd. were used to catalyze the transesterification of dimethyl carbonate (DMC) and glycerol for synthesizing glycerol carbonate (GC). The catalysts were characterized by EDS, XRD, FT-IR, SEM, CO2-TPD and nitrogen adsorption–desorption isotherms. S-CaMgAl MO calcined at 600 °C had excellent catalytic performance due to the large pore size and proper alkalinity. The effects of reaction temperature, reaction time and the amount of catalyst on transesterification were investigated to obtain the optimal reaction conditions. The glycerol carbonate yield reached 96.2% and the glycerol conversion was 98.3% under the condition of 3 wt% catalyst, 1:3 molar ratio of glycerol and DMC, 75 °C reaction temperature and 90 min reaction time. In addition, the GC yield and glycerol conversion still achieved above 90% after five cycles of S-CaMgAl MO.

Synthesis and characterization of TiO2-V2O5-MCM-41 for catalyzing transesterification of dimethyl carbonate with phenol

A series of TiO2-V2O5-MCM-41 molecular sieve catalysts were prepared by the impregnation method. The prepared catalysts were characterized by different techniques including X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and N2 adsorption–desorption. These catalysts were applied in the catalytic synthesis of diphenyl carbonate (DPC) by the transesterification of dimethyl carbonate (DMC) with phenol. The synthesis results indicated that the catalysts possessed the high specific surface area and large pore volume and included titanium with four ligands. Due to the vanadium introduction into Ti-MCM-41, the catalytic activity was promoted, by-products were reduced, and the catalytic activity and stability of the catalyst were significantly improved. With 10%V-20%Ti-MCM-41 catalyst, the optimal synthesis results including the conversion rate of DMC of 33.88%, the selectivity of DPC of 35.84%, and the yield of DPC of 12.14% were obtained.

Transesterification of Dimethyl Carbonate with Phenol to Diphenyl Carbonate Over Magnesium Oxide Nanosheets

Transesterification of Dimethyl Carbonate with Phenol to Diphenyl Carbonate Over Magnesium Oxide Nanosheets

Preparation of polycarbonate diols (PCDLs) from dimethyl carbonate (DMC) and diols catalyzed by KNO3/γ-Al2O3.

γ-Al2O3 loaded with potassium nitrate (KNO3/Al2O3) catalysts were prepared, characterized and employed as a type of heterogenous solid base catalyst in the synthesis of polycarbonate (1,4-butane carbonate)-diol (PBC–OH) via the transesterification of dimethyl carbonate (DMC) and 1,4-butanediol (BD). The relationship between physicochemical properties and catalytic performance for KNO3/Al2O3 in this transesterification reaction was investigated using various techniques. The results demonstrated that the performance of KNO3/Al2O3 catalysts was highly influenced by basic site amount and strength. The medium and strong basic sites were beneficial for this reaction. The catalyst with a KNO3 loading of 35% and a calcination temperature of 700 °C exhibited the best catalytic activity due to its highest basic site amount and appropriate base strength. The highest BD conversion and PBC–OH yield of 80.2% and 68.4% were obtained under optimal reaction conditions. Also, this solid base catalyst was successfully employed in the synthesis of copolycarbonate diols from DMC and two different diols. Different scanning calorimetry results indicated that the thermal properties of the copolycarbonate diols can be adjusted by regulating the average segment lengths, Mn and copolymer composition structure.

Synthesis of glycerol carbonate from transesterification of glycerol with dimethyl carbonate catalyzed by CaO from natural sources as green and economical catalyst

CaO catalysts derived from natural sources were investigated in the transesterification of dimethyl carbonate with glycerol to produce glycerol carbonate. The obtained CaO catalysts were characterized by several techniques, namely TG-DTA, XRD, XRF, BET surface area, SEM, FT-IR, CO2-TPD, and Hammett indicator test. The transesterification was simply monitored and analyzed by NMR technique. Under the optimized reaction conditions of dimethyl carbonate to glycerol molar ratio of 3:1, catalyst loading amount of 3 wt.% and reaction temperature of 80 °C; over 92.1% yield of glycerol carbonate product could be achieved within 2 h.

Dynamic controllability comparison of reactive distillation columns with single and double reactive sections for two-stage consecutive reactions

The purpose of this study is to compare the dynamic controllability of different reactive distillation column configurations including two stage consecutive reversible reactions. Comparison is done between two configurations; the conventional column with single reactive section (RDC-SRS) and the novel column with double reactive sections (RDC-DRS) using two illustrative examples; one ideal generic system and one real system which is the transesterification of dimethyl carbonate with ethanol to form diethyl carbonate. The dynamic results demonstrate that the control performance of RDC-SRS and RDC-DRS are quite similar for both case studies. Thus, the novel RDC-DRS is an acceptable alternative to the conventional RDC-SDR for the separation of two-stage consecutive reversible reactions in terms of both steady-state and control performances.

Di-methyl carbonate transesterification with EtOH over MOFs: Basicity and synergic effect of basic and acid active sites

The catalytic activity of metal-organic frameworks (MOFs) towards the transesterification of dimethyl carbonate with ethanol has been unprecedented assessed. The relation between the catalytic activity and the amount of base active sites has been proved as well as the inability of the Lewis acid sites alone to catalyze this transesterification. The synergic effect of both acid and base sites cannot be completely excluded and a plausible reaction mechanism has been proposed. MOF-808 resulted to be more efficient than every heterogeneous commercial catalyst. MOF-808 can be recycled up to 4 times with exceptional retention of both catalytic activity and crystal structure.

Synthesis of a new “green” sponge via transesterification of dimethyl carbonate with polyvinyl alcohol and foaming approach

In this article, the low toxicity of polyvinyl alcohol (PVA) and dimethyl carbonate (DMC) were used to synthesize polyvinyl alcohol carbonate (PVAC) sponge via a simple transesterification-foaming approach, and the structure and morphology of PVAC sponge were characterized; moreover, the influence of dosage of K2CO3, PVA, distilled water and n-pentane on the water retention capacity of PVAC sponge were investigated, and the influence of reaction temperature and reaction time on the water retention capacity of PVAC sponge were also surveyed. Based on those, it was confirmed that 9.00 g PVA and 5.00 mL DMC in the presence of 2.00 g K2CO3 and 50.00 mL water could be used to synthesize PVAC polymer at 75 °C and for 2.5 h via the transesterification approach, and PVAC polymer in the presence of 5.00 mL n-pentane could be used to synthesize PVAC sponge at 55 °C and for 10 h via the foaming approach, and PVAC sponge owned the structure of six-membered lactone ring and the polyporous morphology, and the maximal water retention capacity was 21.50 g/g.

Excellent performance of TiO2(B) nanotubes in selective transesterification of DMC with phenol derivatives

TiO2(B) nanotubes and anatase TiO2 were synthesized, and the transesterification of dimethyl carbonate (DMC) with phenol and its derivative bisphenol A (BPA) were carried out over them. When reaction was carried out over TiO2(B) nanotube at 150°C, phenol conversion obtained 7.8% and transesterification selectivity reached 99.8%. As reaction temperature increased to 170°C, phenol conversion came up to 54.6% and transesterification selectivity can still maintain a good yield at 99.2%. When bulk BPA reacted with DMC at 150°C, transesterification selectivity and BPA conversion reduced to 92.4% and 3.9%. Raising temperature to 170°C, BPA conversion increased to 43.4%, but transesterification selectivity declined to 90.3%. However, the transesterification of DMC with phenol and BPA took place at 150°C over anatase TiO2, the transesterification selectivity significantly declined to 92.7% and 76.1%, and phenol and BPA conversion only achieved 5.1% and 3.0%. The higher activity of TiO2(B) nanotubes in transesterification was due to its larger surface area, higher pore size and more structure defects. Importantly, in situ DRIFT and TG–MS were used to characterize DMC adsorption, activation and decomposition process over TiO2(B) surface, which provided more information about the mechanism of transesterification and methylation.

Heterogeneous Transesterification of Dimethyl Carbonate and Phenol to Diphenyl Carbonate over Vanadium Pentoxide Microstructures

Vanadium pentoxide (V2O5) microstructures were synthesized by calcining acidtreated NH4VO3 at 773 K in air, which were used as heterogeneous catalysts for the synthesis of diphenyl carbonate (DPC) by the transesterification of dimethyl carbonate (DMC) with phenol. The effects of the types of acid and the transesterification reaction time on catalytic activities were investigated. Under the conditions of reaction temperature of 453 K, a catalyst amount of 0.2% (molar ratio to phenol), molar ratio of DMC/phenol of 1:2 and a reaction time of 13 h, the maximum conversion of DMC and total yields of methyl phenyl carbonate (MPC) and DPC were 23.23 and 23.44%, respectively. The selectivity to the transesterification was nearly 100%. The plausible mechanism of the transesterification catalyzed by the V2O5 microstructures was also probed preliminarily. X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM) characteristics of the catalyst samples had been recorded.

Studies on biodiesel production from DDGS-extracted corn oil at the catalysis of Novozym 435/super absorbent polymer

The corn oil extracted from distillers dried grains with solubles (DDGS), which has a high acid value of 41.6mgKOH/g and a high water content of 4.5%, is used to produce biodiesel in this article. The transesterification of dimethyl carbonate (DMC) and DDGS-extracted corn oil was studied at the catalysis of Novozym 435. Meanwhile, several water removal agents, which include acrylic super absorbent resin (SAP), 4A-molecular sieve, blue silica-gel and tert-butanol, were added to absorb the water during the reaction. The yield of fatty acid methyl esters (FAMEs) was analyzed by GC with internal standard method. The effect of different reaction conditions (type of water absorbent, molar ratio of DMC to oil, reaction time and temperature, lipase and SAP amount) on the yield of FAMEs were also discussed. Then the highest yield of FAMEs could reach 91.0% at 60°C for 18h with molar ratio of DMC to oil 15:1, Novozym 435 amount of 20wt% and SAP amount of 10wt% (based on the oil mass). Finally, Novozym 435/SAP showed excellent operational stability without losing any catalytic activity after 8 cycles of repeated use, and the water absorbed by Novozym 435/SAP can be dried at mild temperature (60°C). Because it is easy to be recycled, the Novozym 435/SAP has a great potential to be used in the continuous biodiesel apparatus such as the fixed bed reactor.