Transesterification Of Ethylene Carbonate Research Articles

La‐Doped Mg‐Al Composite Oxides: Efficient Catalysts for the synthesis of Diethyl Carbonate via Transesterification of Ethylene Carbonate with Ethanol

AbstractSeries of La‐doped Mg−Al composite oxides were prepared by co‐precipitation method and used as catalysts for the synthesis of diethyl carbonate (DEC) via transesterification of ethylene carbonate (EC) with ethanol (EtOH). SEM, XRD, FT‐IR and XPS results confirmed that the introduction of La enhanced the interaction with MgO. The 8 mol % La‐doped Mg−Al composite oxide (calcined catalyst named HTC‐0.8 La) produced strong interactions and improved lattice oxygen content (27.84 %). Based on the N2 adsorption‐desorption and CO2‐TPD results, the HTC‐0.8 La catalysts possessed abundant multistage mesoporous structure, high strong base density and strength (0.941 mmol ⋅ g−1). Therefore, the HTC‐0.8La catalyst exhibited high catalytic activity with 58.5 % yield of DEC and 94.7 % selectivity to DEC (EC: EtOH molar ratio=1 : 6, reaction time=1.5 h, reaction temperature=150 °C and catalyst amount=3.2 wt %). Based on the correlation between catalytic activity and alkalinity, the yield of DEC was positively and linearly related to the strong alkali density of the catalyst. After five replicate experiments, the DEC yield after recovery and roasting reached 54.1 %, indicating that HTC‐0.8La is a renewable heterogeneous catalyst.

Facile one-pot synthesis of niobium-containing carbon nitride and the catalytic application for synthesis of dimethyl carbonate

Dimethyl carbonate (DMC) is a building block in wide chemical-related fields and the transesterification of ethylene carbonate (EC) and methanol/ethanol is a sustainable route for the synthesis of DMC. Herein, in order to explore efficient heterogeneous catalysts, niobium-containing carbon nitride materials were synthesized by a convenient one-pot calcination method. By reserving the main chemical functionalities of carbon nitride, the Nb-CN composites contained both acidic and basic properties, and Nb can be dispersed by carbon nitride. In the transesterification of EC with methanol, under the reaction temperature of 140 °C and reaction time of 4 h, the conversion of EC and the selectivity of DMC reached 53.8% and 100%, respectively, and the activity of the catalyst did not decrease significantly after several recycling runs. Furthermore, the Nb-CN could promote transesterification reactions of other cyclic carbonate and alcohols.

Synthesis of Dimethyl Carbonate via Transesterification of Ethylene Carbonate and Methanol over Mesoporous KF-loaded Mg-Fe Oxides.

A series of KF/Mg-Fe oxides were fabricated via the solid-state reaction between KF and Mg-Fe oxides. Especially, when 20 wt % KF was supported on the Mg-Fe bi-metal oxides and calcined at 400-600 °C, the solid material with more basic sites than the support itself was obtained. When applied as catalyst to dimethyl carbonate (DMC) synthesis through transesterification of ethylene carbonate (EC) and methanol, this material can afforded up to 88 % yield and 97 % selectivity toward DMC in 2 h under reflux conditions with the molar ratio of methanol to ethylene carbonate set at 8. It is worth noting that the catalyst was easily separated and reused, retaining at least 89 % catalytic activity during the first four recycles. Although an attenuated activity was still observed due to the inevitable filtration loss and dissolution, this solid base can still provide clues to the development recyclable catalyst in green synthesis of DMC.

Acid–base bifunctional ZnNbCl/eg-C3N4 materials towards catalytic synthesis of dimethyl carbonate via transesterification of ethylene carbonate

The catalytic transesterification reaction between ethylene carbonate (EC) with methanol is a sustainable approach for the production of dimethyl carbonate (DMC). In this work, exfoliated carbon nitride (eg-C3N4) was supported with ZnCl2 and NbCl5. The synthesized materials (ZnNbCl/eg-C3N4) were analyzed by XRD, N2 adsorption–desorption, FT-IR, XPS, SEM, TG, CO2-TPD, and NH3-TPD. The eg-C3N4 could disperse well Zn2+ and Nb5+ species via nitrogen-containing groups. The combined Zn2+ and Nb5+ components enhanced the alkaline strength of eg-C3N4 and introduced acidic sites, enabling ZnNbCl/eg-C3N4 as solid-base bifunctional catalysts. As heterogeneous catalysts, ZnNbCl/eg-C3N4 exhibited superior activity to ZnCl2/eg-C3N4 or NbCl5/eg-C3N4 in the transesterification of EC. At 140 °C of reaction temperature, EC conversion and DMC selectivity reached 80.1% and 100%, respectively. The catalysts showed good recycling performance and were also compared with other recently reported heterogeneous catalysts.

NaCl catalyzed transesterification and hydrolysis of ethylene carbonate

Sodium chloride (NaCl) was used as catalyst for the production of bulk chemicals of dimethyl carbonate and ethylene glycol by transesterification of ethylene carbonate with methanol first time in high activity with a TON of 770. Mechanism studies by kinetic isotope effect measurements and DFT calculations indicated that NaCl acted as Lewis base to catalyze transesterification via the SN2 mechanism. Moreover, NaCl was demonstrated to be an effective catalyst for the hydrolysis of ethylene carbonate.

Rocket-Shaped Telluroniobate with Efficient Catalytic Activity in the Transesterification Reaction.

A novel telluroniobate, K8Na6H7{[Co(en)2(SO3)][Te4Nb24O79]}·42H2O (en = ethylenediamine), has been synthesized through a diffusion strategy. It consists of a heteropolyoxoniobate [B-β-TeNb9O33]17- cluster and isopolyoxoniobate {Nb7O22} building blocks. In addition, its structure was fully characterized by a series of spectroscopic methods. Furthermore, it exhibits an efficient catalytic performance in the transesterification of ethylene carbonate and methanol to prepare dimethyl carbonate with good catalytic reusability. Also, it demonstrates interesting proton conduction properties, with conductivity achieved at 3.05 × 10-4 S cm-1 (60 °C, 75% relative humidity).

Synthesis of Dimethyl Carbonate via Transesterification of Ethylene Carbonate and Methanol using Recyclable Li/NaY Zeolite

AbstractIn this work, the novel solid base Li/NaY was prepared via the solid state reaction between NaY zeolite and Li2CO3 at high temperature. When applied to the dimethyl carbonate (DMC) preparation through transesterification of ethylene carbonate (EC) and methanol, up to 89% yield of DMC with 99% selectivity can be accessed. The characterization results reveal the as‐synthesized Li/NaY possesses higher basicity than NaY. Furthermore, the Lewis acidity of the Li/NaY material is also enhanced due to the incorporation of lithium. Therefore, the Li/NaY can act as a dual functional catalyst in the transesterification reaction, thus leading to high efficiency. Notably, this catalyst can be easily recovered and reused for at least six times without obvious activity loss. This work provides a green synthetic route to DMC production and also sheds light on the development of solid basic catalysts.

Excess soluble alkalis to prepare highly efficient MgO with relative low surface oxygen content applied in DMC synthesis

The activities of various MgO catalysts, which were prepared from different methods such as hydration synthesis, thermal decomposition, combustion, sol–gel and co-precipitation, were conducted in dimethyl carbonate (DMC) synthesis via transesterification of ethylene carbonate with methanol. MgO-P-Na2CO3-3.14 synthesized by the excess Na2CO3 precipitation compared the best catalytic activity and stability, which could be reused for seven times without obvious deactivation. The DMC yield was as high as 69.97% at 68 °C. The transesterification reaction could be separated into two steps, and the samples obtained by NaOH precipitant exhibited better ring-opening capability, while the catalysts acquired by Na2CO3 precipitant displayed superior transesterification ability. The structure-performance relationship was evaluated by multiple characterization methods. The results indicated that the as-synthesized catalyst derived from dried precursors with more crystalline magnesium carbonate was favorable for the promotion of DMC yield, and MgO-P-Na2CO3-3.14 with more Mg-O pairs, which were the active center for the transesterification of 2-hydroxyethyl methyl carbonate (HEMC) intermediate with methanol, resulted in more moderately basic sites left that was in accordance with the DMC yield variation. MgO-P-Na2CO3-3.14 with greater BET surface area and mesopore volume, relative low surface oxygen content and larger moderately basic sites amount compared the excellent activity in DMC synthesis.

Efficient synthesis of dimethyl carbonate via transesterification of ethylene carbonate catalyzed by swelling poly(ionic liquid)s

The synthesis of dimethyl carbonate (DMC) via transesterification of ethylene carbonate (EC) and methanol (MeOH) was an environmental and practical strategy. Herein, poly(ionic liquid)s (PILs) with swelling abilities were synthesized by free radical copolymerization of N-vinylimidazolium ionic liquids, sodium 4-vinylbenzoate and cross-linker 1,8-triethylene glycoldiyl-3,3ʹ-divinylimidazolium bromide ([(EG)3-DVIm]Br2). The swelling abilities of PILs in various solvents were measured, and PILs could swell in methanol (MeOH). The swelling ability of PILs in MeOH could be modulated by changing the cross-linker content and chain length of 3-alkyl-substituents on imidazolium. The swollen state of PILs in MeOH presented a porous cross-linked network structure observed by the cryo-scanning electron microscope (cryo-SEM). The swelling PILs were used to catalyze the transesterification of ethylene carbonate (EC) and MeOH to prepare the DMC, and the catalytic activities was correlated with the swelling abilities of PILs. The PIL with 3-butyl-substituent and 2.5 mol% cross-linker (poly[VBIm-VBA-DVIm]-2.5%) had the highest swelling ratio (Q = 12.4 (g/g)) in MeOH and EC mixed solvents and exhibited excellent catalytic activities, which was similar to corresponding homogeneous ionic liquid. Furthermore, the catalyst could be reused up to seven runs without any considerable loss of its initial activity.

Design and optimization of reactive dividing-wall extractive distillation process for dimethyl carbonate synthesis based on quantum chemistry and molecular dynamics calculation

• Selection of extractants based on quantum chemistry and molecular dynamics calculation. • The process of dimethyl carbonate production by transesterification was designed. • Economic and environmental optimization of several different production separation processes. The preparation of dimethyl carbonate by transesterification of ethylene carbonate and methanol has an important application in industry. The preparation of dimethyl carbonate by reactive distillation and the efficient separation of dimethyl carbonate and methanol are the inevitable requirements of the sustainable development of extractive distillation. Based on the quantum chemistry calculation and molecular dynamics calculation analysis, a better extractant (2-Furaldehyde) was selected. The simulated extractive distillation was designed to separate dimethyl carbonate methanol. The σ - profile was drawn by using COSMO-SAC model, and three different separation processes of dimethyl carbonate production were compared and optimized. Taking TAC as the objective function, the separation process of reactive dividing-wall extractive distillation can reduce about 21% and carbon dioxide emission by about 10% compared with the common reactive distillation process, which has obvious economic advantages and environmental performance. Through the economic and environmental optimization analysis of the production and separation process of dimethyl carbonate, it provides a certain guiding significance for the actual production of dimethyl carbonate and the separation of dimethyl carbonate methanol.

One-step bulk fabrication of a CaO/carbon heterogeneous catalyst from calcium citrate for rapid synthesis of dimethyl carbonate (DMC) by transesterification of ethylene carbonate (EC)

Providing a simpler, more economical and more innovative method for rapid preparation of carbon-based inorganic nanoparticles.

Transesterification of ethylene carbonate with methanol over Zn-La mixed oxide catalysts

The transesterification of ethylene carbonate (EC) with methanol to synthesis dimethyl carbonate (DMC) and ethylene glycol (EG) over ZnO, La2O3 and Zn-La mixed oxides were explored. The catalysts were prepared by co-precipitation method and characterized by BET, XRD, TG-DSC, CO2-TPD and Hammett titration. The influence of Zn/La atomic ratio, calcination temperature and reaction parameters (reaction temperature, reaction time, catalyst amount) on the catalytic activity were investigated. The results indicated that the binary Zn-La mixed oxide with Zn/La atomic ratio of 2:1 calcined at 500°C showed the highest catalytic performance for the title reaction due to its strongest basicity, and the amount of strong basic sites of the catalyst should be responsible for the high transesterification activity.

Calcium oxide-modified mesoporous silica loaded onto ferriferrous oxide core: Magnetically responsive mesoporous solid strong base

The design of new type of solid strong base with ideal activity, stability, and reusability is strongly urged by the growing demand of green chemistry and sustainable development. In this study, a new type of mesoporous solid strong base, denoted as CaO/mSiO2/Fe3O4, is successfully fabricated by successively coating SiO2 onto Fe3O4 magnetic nanoparticles and loading CaO into the mesoporous SiO2. Compared with a series of other typical solid bases, the CaO/mSiO2/Fe3O4 exhibits higher activity towards the synthesis of dimethyl carbonate by the transesterification of ethylene carbonate and methanol. The activity of the CaO/mSiO2/Fe3O4 is not observed to decrease obviously even after sextic catalyst recirculation, and in particular, the recovery of the catalyst without quality loss is very convenient due to the good magnetic responsiveness of the Fe3O4 cores.

The preparation and efficacy of SrO/CeO2 catalysts for the production of dimethyl carbonate by transesterification of ethylene carbonate

The need for eco-friendly fuels has given a fillip to search for new molecules and their cost-effective synthesis. A series of ceria-strontium (CexSr1−xO2; x = 0 to 1) catalysts were prepared by a citric acid assisted sol–gel method. These catalysts were characterized by BET, XRD, SEM-EDAX, ICP-MS, FTIR, NH3-TPD and CO2-TPD techniques and tested for the synthesis of dimethyl carbonate (DMC) in a batch reactor for the transesterification of ethylene carbonate (EC). The activity of the synthesized catalysts was found to be closely related to basic and acidic sites, and the surface area of the catalysts. The catalyst, Ce0.6Sr0.4, showed highest basicity and acidity, and was found to be most effective in the formation of DMC from transesterification of EC. Reactions were carried out by varying the particle size (50–800 μm) and agitation speed (200–600 rpm) for minimizing the internal mass transfer resistance and the external mass transfer resistance, respectively. Further, Ce0.6Sr0.4 catalyst was used to optimize the reaction conditions such as methanol/EC molar ratio (in the range of 4–12), catalyst dose (in the range of 2–5 wt% of EC), reaction time (in the range of 2–6 h) and temperature (in the range of 100–180 °C) for DMC yield and EC conversion. At the optimum conditions of methanol/EC molar ratio of 8, 3 wt% of catalyst, 5 h reaction time and 150 °C temperature, the DMC selectivity was 87% and EC conversion of 82%, with a reaction rate of ∼0.547 mol/L.h (with respect to EC). The reusability of the Ce0.6Sr0.4 catalyst for EC conversion with turn-over frequency and DMC selectivity were also studied.

MgFeCe Ternary Layered Double Hydroxide as Highly Efficient and Recyclable Heterogeneous Base Catalyst for Synthesis of Dimethyl Carbonate by Transesterification

A series of Mg3:Fex + Ce1−x LDHs (3:1) were synthesized by co-precipitation method by varying molar ratio of Fe:Ce between 1:0 to 0:1 (LDH-1 to LDH-6). All synthesized LDHs were characterized by XRD, FT-IR, TEM, N2 sorption, benzoic acid titration and XPS in detail and evaluated for selective synthesis of dimethyl carbonate by transesterification of ethylene carbonate with methanol. It was demonstrated that the structural and basic properties of synthesized LDHs were strongly dependent on the Fe:Ce molar ratio (Ce concentration). The correlation between their physicochemical properties and catalytic performance was studied in detail. Among all synthesized LDHs the best result was obtained with LDH-3 (Fe:Ce = 0.85:0.15) where LDH structure remained intact, and showed high number of strong basic sites on LDH surface. LDH-3 was recycled 7 times while maintaining high catalyst activity and selectivity towards DMC. The obtained results elucidate the important role of Ce in modifying the basic properties of LDH in enhancing the catalytic activity for DMC synthesis.

Layered double hydroxides as base catalysts for the synthesis of dimethyl carbonate

In this work, we have prepared two series of layered double hydroxides (LDHs) based on three different divalent cations (Zn2+, Ni2+ and Mg2+), that were ion-exchanged by a trivalent cation (Al3+). The charge was balanced with interlayer anions, either silicate or carbonate. Thus, we have synthetized six different samples and we have studied their physicochemical properties by a wide range of techniques, in order to elucidate their properties. Finally, we have used the prepared materials as catalysts in the transesterification of ethylene carbonate with methanol to produce dimethyl carbonate and ethylene glycol. We have found that materials containing Ni as divalent cation present better catalytic activity due to their basic properties, whereas catalysts containing silicate as interlayer anion yield better selectivity, since they have a lower amount of acid sites.

Simple preparation of MgO/g-C3N4 catalyst and its application for catalytic synthesis of dimethyl carbonate via transesterification

Graphitic carbon nitride (g-C3N4) was employed as a catalyst support to load MgO. The physicochemical properties of the supported catalyst (MgO/g-C3N4) were characterized using several characterization techniques, including XRD, FT-IR, SEM, XPS and CO2-TPD. The incorporation of MgO has effectively enhanced the overall basicity of g-C3N4. In the transesterification of ethylene carbonate (EC) with methanol to dimethyl carbonate (DMC), MgO/g-C3N4 catalysts demonstrated high catalytic activity and good recyclability, affording the maximum DMC yield of 70% at 140°C. Moreover, the catalytic performance has also been compared with other reported heterogeneous catalysts.

Dimethyl carbonate synthesis via transesterification of ethylene carbonate and methanol using ionic liquid catalysts immobilized on mesoporous cellular foams

Dimethyl carbonate (DMC) was synthesized via transesterification of ethylene carbonate and methanol with ionic liquid catalysts. For this reaction, 1,4-diazobicyclo[2.2.2]octane (DABCO), [Choline]OH, and [BMIM]Cl were used as a homogeneous catalyst, and hydrotalcite, [DABCO]OH@MCF, [DABCO]Cl@MCF, and DABCO/MCF were used as a heterogeneous catalyst. To support the ionic liquids, mesoporous cellular foam (MCF) was prepared and characterized by SEM, TEM and BET surface area analyzer. The average cell and window sizes of the prepared MCF were 34.4 and 21.3 nm, respectively. The prepared MCF had a well structured three-dimensional structure. Among the homogeneous catalysts used, DABCO showed the highest DMC yield about 84 %, and among the heterogeneous catalysts, [DABCO]OH@MCF showed the highest DMC yield about 77 %. In the reusability test of the used catalysts, there was only 8 % point decrease in DMC yield with [DABCO]OH@MCF, whereas 58 percent point decrease in DMC yield with DABCO/MCF after four times recycling tests. The effects of an anion on the catalytic activity were investigated. The optimum reaction condition for DMC synthesis was also investigated with [DABCO]OH@MCF catalyst.

Fast and facile preparation of metal-doped g-C3N4 composites for catalytic synthesis of dimethyl carbonate

Zn-doped g-C3N4 materials (Zn-g-C3N4) were prepared by a simple mixing and calcination, using dicyandiamide as a precursor and zinc halide as a dopant. The characterization results of CO2 temperature-programmed desorption and elemental analysis revealed that the introduction of Zn species enhanced the overall basic quantity of g-C3N4. In the transesterification of ethylene carbonate with CH3OH to dimethyl carbonate (DMC), the Zn-g-C3N4 catalysts showed superior catalytic activity to the pure g-C3N4, and the highest DMC yield reached 83.3%, along with stable catalytic reusability and reproducibility. Furthermore, other transition-metal halides (including FeCl3, CuCl2, NiCl2, etc.) could be utilized as dopants for g-C3N4, and the obtained doped g-C3N4 materials also showed high EC conversions above 70%. The upgradation of basic quantity of g-C3N4 was attributed to the reaction between metal halide and the active amine species of g-C3N4. Despite their low surface areas, under the same catalytic conditions, Zn-g-C3N4 catalysts demonstrated remarkably higher catalytic activity than other mesoporous carbon nitride materials.

Efficient synthesis of dimethyl carbonate via transesterification of ethylene carbonate over a new mesoporous ceria catalyst

Mesoporous ceria materials (CeO2-meso) have been prepared through a soft-templating method using cetyltrimethylammonium bromide as a template and cerium nitrate as a precursor. The synthesized CeO2-meso materials possess narrow pore size distributions of 5.1–5.4nm and tunable surface areas (109–182 m2g−1). As heterogeneous catalysts in the transesterification of ethylene carbonate (EC) with methanol to dimethyl carbonate (DMC), CeO2-meso materials demonstrate superior catalytic performance to the commercial ceria. N2 adsorption–desorption and CO2-TPD characterization results indicate that the catalytic activity obtained over various CeO2-meso samples depends on their surface areas and basicity. The highest activity is achieved over CeO2-meso-400, affording a DMC yield as much as 73.3%, together with excellent recycling ability. Besides the transesterification of EC with methanol, CeO2-meso is found to be able to catalyze the reactions of other cyclic carbonates and alcohols. In view of the high catalytic performance along with the convenience in catalyst preparation, CeO2-meso-400 compares favorably with the ionic liquids as well as other ceria-based catalytic systems.