Synthesis Of Dimethyl Carbonate Research Articles

A Review of Catalysts for Synthesis of Dimethyl Carbonate

Dimethyl carbonate (DMC) is widely used as an intermediate and solvent in the organic chemical industry. In recent years, compared with the traditional DMC production methods (phosgene method, transesterification method), methanol oxidation carbonylation method, gas-phase methyl nitrite method, and the direct synthesis of CO2 and methanol method have made much progress in the synthesis process and development of catalysts. The key to the industrial application of DMC synthesis technology is the design and development of high-performance catalysts. Therefore, this paper reviews the research status of the methanol oxidative carbonylation method, gas-phase methyl nitrite method, and direct synthesis method of CO2 and methanol in the aspects of new catalyst design, catalyst preparation, and catalytic mechanism, and puts forward the problems to be solved and the future development direction of DMC catalysts.

Dimethyl Carbonate Synthesis from CO2 over CeO2 with Electron‐Enriched Lattice Oxygen Species

AbstractDirect synthesis of dimethyl carbonate (DMC) from CO2 plays an important role in carbon neutrality, but its efficiency is still far from the practical application, due to the limited understanding of the reaction mechanism and rational design of efficient catalyst. Herein, abundant electron‐enriched lattice oxygen species were introduced into CeO2 catalyst by constructing the point defects and crystal‐terminated phases in the crystal reconstruction process. Benefitting from the acid‐base properties modulated by the electron‐enriched lattice oxygen, the optimized CeO2 catalyst exhibited a much higher DMC yield of 22.2 mmol g‐1 than the reported metal‐oxide‐based catalysts at the similar conditions. Mechanistic investigations illustrated that the electron‐enriched lattice oxygen can provide abundant sites for CO2 adsorption and activation, and was advantageous of the formation of the weakly adsorbed active methoxy species. These were facilitating to the coupling of methoxy and CO2 for the key *CH3OCOO intermediate formation. More importantly, the weakened adsorption of *CH3OCOO on the electron‐enriched lattice oxygen can switch the rate‐determining‐step (RDS) of DMC synthesis from *CH3OCOO formation to *CH3OCOO dissociation, and lower the corresponding activation barriers, thus giving rise to a high performance. This work provides insights into the underlying reaction mechanism for DMC synthesis from CO2 and methanol and the design of highly efficient catalysts.

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.

Boosting Dimethyl Carbonate Production from CO2 and Methanol using Ceria-Ionic Liquid Catalyst.

As a crucial strategy towards a sustainable chemical industry, the direct synthesis of dimethyl carbonate (DMC) from renewable carbon dioxide (CO2) and methanol (MeOH) is studied using CeO2 nanoparticles modified with 1-butyl-3-methylimidazolium hydrogen carbonate ([BMIm][HCO3]) devoid of stoichiometric dehydrating agents. The synthesized CeO2@[BMIm][HCO3] catalyst having high thermal stability harnesses the unique physicochemical properties of CeO2 and the ionic liquid to exhibit a DMC yield of 10.4 % and a methanol conversion of 16.1 % at optimal conditions (pressure of CO2=5 MPa; temperature=130 °C). The catalytic behavior of CeO2@[BMIm][HCO3] studied with a detailed XRD, XPS, CO2 and NH3-TPD, Raman spectroscopy, TGA, FTIR, SEM and TEM suggests that the synergy between the two catalytic components originating from an increased surface oxygen vacancies boosts the overall catalytic performance. After several recycling tests, the catalyst demonstrated no significant reduction in DMC yield and methanol conversion. This platform is an attractive approach to synthesize thermally stable nanoparticle@ionic liquid that retains and merges the physical attributes of both materials for producing useful bulk chemicals from readily available chemical resources.

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.

Dimethyl Carbonate Synthesis from CO2 over CeO2 with Electron-Enriched Lattice Oxygen Species.

Direct synthesis of dimethyl carbonate (DMC) from CO2 plays an important role in carbon neutrality, but its efficiency is still far from the practical application, due to the limited understanding of the reaction mechanism and rational design of efficient catalyst. Herein, abundant electron-enriched lattice oxygen species were introduced into CeO2 catalyst by constructing the point defects and crystal-terminated phases in the crystal reconstruction process. Benefitting from the acid-base properties modulated by the electron-enriched lattice oxygen, the optimized CeO2 catalyst exhibited a much higher DMC yield of 22.2 mmol g-1 than the reported metal-oxide-based catalysts at the similar conditions. Mechanistic investigations illustrated that the electron-enriched lattice oxygen can provide abundant sites for CO2 adsorption and activation, and was advantageous of the formation of the weakly adsorbed active methoxy species. These were facilitating to the coupling of methoxy and CO2 for the key *CH3OCOO intermediate formation. More importantly, the weakened adsorption of *CH3OCOO on the electron-enriched lattice oxygen can switch the rate-determining-step (RDS) of DMC synthesis from *CH3OCOO formation to *CH3OCOO dissociation, and lower the corresponding activation barriers, thus giving rise to a high performance. This work provides insights into the underlying reaction mechanism for DMC synthesis from CO2 and methanol and the design of highly efficient catalysts.

Synergistic effect of the framework boron and Al-rich region to enhance the metal-support interaction for boosting Pd-based catalyst activity of dimethyl carbonate synthesis

Efficient production of dimethyl carbonate (DMC) from methyl nitrite (MN) carbonylation based on PdCu/NaY zeolite catalysts is highly desired for industrial applications. The introduction of boron species into the initial gels of NaY synthesis is a cost-effective modification strategy for boosting the catalytic performance. It not only introduces trace amounts of framework boron but also regulates the distribution of framework aluminum (AlF) species. Most importantly, the synergistic effect of framework boron and Al-rich region significantly enhanced the metal − support interaction, thus promoting more electrons to be transferred from metal to support. This strategy allows the palladium active species to remain in an electron-deficient state more easily. The carbon monoxide (CO) adsorption and the critical intermediate species *CH3COO are more easily formatted on PdCu/NaBY catalyst, which leads to superior weight-time yields (WTYDMC up to 1507·g·kgcat − 1·h− 1), and CO conversion to DMC (CCO up to 83 %). Our design is of great importance for developing metal-zeolites catalysts, which motivates the industrial application of Pd-based catalysts in the MN carbonation of DMC field.

Enhancing DMC Production from CO2: Tuning Oxygen Vacancies and In Situ Water Removal

The direct synthesis of dimethyl carbonate (DMC) from methanol and CO2 presents an attractive route to turn abundant CO2 into value-added chemicals. However, insufficient DMC yields arise due to the inert nature of CO2 and the limitations of reaction equilibrium. Oxygen vacancies are known to facilitate CO2 activation and improve catalytic performance. In this work, we have demonstrated that tuning oxygen vacancies in catalysts and implementing in situ water removal can enable highly efficient DMC production from CO2. CexZryO2 nanorods with abundant oxygen vacancies were synthesized via a hydrothermal method. In liquid-phase DMC synthesis, the Ce10Zr1O2 nanorods exhibited a 1.7- and 1.4-times higher DMC yield compared to CeO2 nanoparticles and undoped CeO2 nanorods, respectively. Zr doping yielded a CeZr solid solution with increased oxygen vacancies, promoting CO2 adsorption and activation. In addition, adding 2-cyanopyridine as an organic dehydrating agent achieved an outstanding 87% methanol conversion and >99% DMC selectivity by shifting the reaction equilibrium to the desired product. Moreover, mixing CeO2 nanoparticles with hydrophobic fumed SiO2 in gas-phase DMC synthesis led to a doubling of DMC yield. This significant increase was attributed to the faster diffusion of water molecules away from the catalyst surface, facilitated by the hydrophobic SiO2. This study illustrates an effective dual strategy of enhancing oxygen vacancies and implementing in situ water removal to boost DMC production from CO2. The strategy can also be applied to other reactions impacted by water accumulation.

Direct synthesis of dimethyl carbonate from CO2: From the perspective of dimethyl-carbonate, a promising material for the future

Greenhouse gas (GHG) emissions have grown and reached 33.9 Gt of CO2 equivalents in 2020. Its amounts have continuously increased since the industrial revolution, so, carbon capture and utilization and storage (CCUS) technology can mitigate CO2 emission and global warming. Dimethyl Carbonate (DMC) has attracted attention as it is used as a solvent in lithium-ion batteries. We proposed a modified process simulation based on the fractional converion of experiment of direct synthesis of the DMC using CO2. Also, to separate azeotropic mixture, ethylene glycol is used as an entrainer. We changed the feed of the CO2 and changed the design when CO2 feed is lower than stoichiometry ratio. Economic feasibility for all cases was evaluated using Aspen Process Economic Analyzer (APEA) V12. As a result, the total annual cost for the case 1, 2 and 3 is US 9.88 M$/yr, US 9.71 M$/yr and US 10.3 M$/yr, respectively. The Net Present value (NPV) for the case 1,2 and 3 is US − 51.6 M$, US − 56.66 M$/yr and US − 56.1 M$. Sensitivity analysis is performed to examine the effect of the NPV while changing the economic parameters such as utility cost and DMC selling price from − 30% to 30%. The most effective parameter of the NPV is the selling price of the DMC for case 1 and utility cost for case 2 and 3. A lower DMC selling price and solving deactivation problem of catalyst are the potential to develop the CCU technology.

Construction of stable heterogeneous catalysts with alkali metals loaded on weakly alkaline carbon-nitrogen materials for transesterification

It is important to enhance the basicity of solid catalysts for the application of heterogeneous catalysts in the synthesis of dimethyl carbonate. Notably, the role of the carrier in the supported solid base catalyst cannot be ignored. Herein, the catalyst (named 1.0Ca/g-C3N4 (M)), prepared by one-step thermal polymerization, achieved a yield of 68.4 % and a selectivity of 96.8 % for DMC and maintained its performance after four consecutive cycles at 130 °C. It could be seen from the characterization that the amino group on the surface of the carrier, as an electron pushing group, endowed the Ca connected at its end with more abundant valence electrons, so that the catalyst exhibited a higher alkalinity. This study provides a new reference for the development of multiphase catalysts in transesterification reactions.

Characterization of alkaline earth metal-doped CeO2 nanocatalysts and their catalytic activities in the synthesis of dimethyl carbonate through a reaction between methanol and CO2

Alkaline earth metal (Mg2+, Ca2+, Sr2+, and Ba2+)-doped CeO2 nanocatalysts have been prepared by the successive co-precipitation and calcination method.

Design of Dimethyl Carbonate (DMC) Synthesis Process Using CO2, Techno-economic Analysis, and Life Cycle Assessment

Design of Dimethyl Carbonate (DMC) Synthesis Process Using CO2, Techno-economic Analysis, and Life Cycle Assessment

CeO2-Decorated α-Fe2O3 Nanorings for the Direct Synthesis of Dimethyl Carbonate from CO2 and Methanol

CeO₂-Decorated α-Fe₂O₃ Nanorings for the Direct Synthesis of Dimethyl Carbonate from CO₂ and Methanol

Synthesis of dimethyl carbonate from CO2 catalyzed by spherical polymeric ionic liquid catalyst

Synthesis of dimethyl carbonate from CO2 catalyzed by spherical polymeric ionic liquid catalyst

Surface engineering of CexBi1−xO2−δ nanorods rich in oxygen vacancies for enhancing photo-thermal synthesis of dimethyl carbonate from CO2/CH3OH

The utilization of oxygen vacancies to modulate the surface properties of catalysts is a powerful way to enhance catalytic activity. In this work, the doping effect of Bi3+ on the performance of CeO2−δ (CexBi1−xO2−δ) hybrid nanorods with rich oxygen vacancies for the photo-thermal synthesis of dimethyl carbonate (DMC) from CO2/CH3OH (140 ℃, 1.6 MPa, 4 h) is systematically investigated. It is found that Ce0.9Bi0.1O2−δ exhibits the best catalytic performance, achieving a photo-thermal yield of 3.13 mmol∙g−1 without any dehydrating agent (1.14 times compared to thermal catalysis). It turns out that regulating the concentration of Bi3+ ions not only modifies the oxygen vacancy content, but also improves the light harvesting efficiency. Moreover, a series of characterization techniques, such as X-ray photoelectron spectroscopy, Raman spectrometer and electron paramagnetic resonance are employed to analyze and verify that the asymmetric oxygen vacancies are conducive to the improvement in the CO2 adsorption-activation. Finally, a possible reaction mechanism model of Bi3+ doping on CeO2−δ for the photo-thermal synthesis of DMC from CO2 and CH3OH is proposed. This work provides a practical approach to catalyst surface engineering design.

CeO2 nanorods with bifunctional oxygen vacancies for promoting low-pressure photothermocatalytic CO2 conversion with CH3OH to dimethyl carbonate

The direct synthesis of dimethyl carbonate (DMC) from CO2 and methanol is a kind of highly-attractive route for CO2 conversion to high value-added chemicals. However, a key core problem is how to more effectively activate CO2. Here, we adopt simple template-free hydrothermal method to prepare CeO2 nanorods with oxygen vacancies and introduce light energy into the thermal catalysis system for promoting low-pressure photothermalcatalytic CO2 with methanol direct conversion to DMC. The SEM, HRTEM, XRD, XPS, N2 adsorption-desorption isotherm, CO2-TPD, EPR, Raman, photoluminescence spectra and UV-Vis-IR DRS characterizations are carried out to analyze the microscopical properties including the crystal phases, chemical states, structural features, optical properties for building up the intrinsic relationship with macroscopic performance. Our findings reveal that oxygen vacancies can not only act as photo-produced charge trapping center to prevent the recombination of photoinduced electrons and holes, but also promote CO2 adsorption and activation abilities through Lewis acid-base interaction. Finally, the detailed action mechanism for photothermalcatalytic CO2 conversion with methanol to DMC is proposed. This work should provide new ideas and insights for achieving the CO2 conversion into high value-added long-chain chemicals.

Direct synthesis of dimethyl carbonate from CO2 and methanol over a novel CeO2-zeolite Beta composite catalyst

Direct synthesis of dimethyl carbonate from CO2 and methanol over a novel CeO2-zeolite Beta composite catalyst

Comparative Study between 2-Furonitrile and 2-Cyanopyridine as Dehydrants in Direct Synthesis of Dialkyl Carbonates from CO2 and Alcohols over Cerium Oxide Catalyst.

The shift of equilibrium by removing water with nitrile dehydrants is crucial for CeO2 -catalyzed synthesis of dialkyl carbonates from CO2 and alcohols. Two nitriles - 2-cyanopyridine and 2-furonitrile - were previously found as effective dehydrants, yet their detailed comparison as well as exploration of potential of 2-furonitrile remain insufficient. Herein, the performance of 2-cyanopyridine and 2-furonitrile was compared in the synthesis of various dialkyl carbonates. 2-furonitrile was found to be superior to 2-cyanopyridine in the synthesis of dialkyl carbonates from CO2 and bulky or long-chain (≥C3) alcohols. Namely, the yield of diisopropyl carbonate (up to 50 %) achieved using CeO2 and 2-furonitrile is comparable to or even higher than previously reported ones. Meanwhile, 2-cyanopyridine acted as a better dehydrant than 2-furonitrile in the synthesis of dimethyl carbonate and diethyl carbonate. The adsorption experiments and density functional theory calculations have indicated that the better performance of 2-furonitrile compared to 2-cyanopyridine in the synthesis of dialkyl carbonates from bulky or long-chain alcohols is due to the weaker interaction of 2-furonitrile with the CeO2 surface. Such weak interaction of 2-furonitrile offers a larger reaction field on the catalyst surface for both CO2 and alcohols.

Exothermic barrier-free carboxylation of alkali methylates. The highest-yield synthesis of dialkyl carbonates out of alcohols and carbon dioxide rationalized and reformulated through quantum-chemical simulations

While the Earth’s atmosphere represents an abundant source of CO2, its valorization by humanity remains at a nascent stage. Synthesizing added-value products out of CO2 and suitable co-reactants is an urgent and appealing chemical challenge to pursue in our busy times. Herein, we perform a rationalization, extension, and ultimate reformulation of the recently proposed highest-yield synthesis of dimethyl carbonate (DMC) and generally dialkyl carbonates out of alcohols and CO2 employing quantum-chemical reaction modeling. The carboxylation of pure methanol (CH3OH) by CO2 is thermochemically prohibited (+33 kJ/mol) and hindered by a heavy activation energy barrier (160 kJ/mol). The existing catalysts decrease the above barrier twice. The catalyzed carboxylation exhibits yields of 5–15 % of DMC depending on a specific catalyst, dehydration agents, and pressure elevation. In turn, the usage of alkali metal methylates – such as CH3OLi, CH3ONa, CH3OK, and CH3ORb – as reactants, instead of CH3OH, fully eliminates the activation barrier. Furthermore, alcoholates make carboxylation exothermic. We stepwise rationalize the origin of such a desirable behavior in terms of thermochemistry, molecular geometries, atomic nucleophilicities, potential energy landscapes, and computed vibrational spectra. All methylates perform decently and exhibit reasonable similarities as reactants. The most favorable reaction was recorded in the case of sodium alcoholate (according to Gibbs free energy) and lithium alcoholate (according to enthalpy). Since the carboxylation smoothly proceeds with the methylates, the synthesis can be carried out under normal conditions. This is contrary to the elevated temperatures and pressures, which have to be routinely supplied to implement the presently known catalytic schemes. Apart from an organic carbonate, the novel reactions produce LiI, NaI, KI, and RbI as major products. The consumed alkali metals need to be restored, for instance, by utilizing electrolysis, for their repetitive usages. The theoretical results are discussed tightly in the context of the recent experiments. The reactions can take place in liquid CH3OH. Exemplified computationally for the methyl radical, the invented scheme must generally work for larger hydrocarbon moieties. This report will interest synthetic chemists, whose work is devoted to the valorization of CO2.

Breaking azeotropes by reactive adsorption: A case for sorption-enhanced dimethyl carbonate synthesis

This work investigates the direct production of dimethyl carbonate (DMC) from CO2 by sorption-enhanced DMC (SEDMC) synthesis, employing modelling techniques. SEDMC synthesis is shown to be an exemplary case for reactive separation, as it enhances the reaction and simplifies downstream processing through in-situ separation. By incorporating in-situ water adsorption, SEDMC achieves significantly higher methanol conversions compared to other direct synthesis routes. Simultaneously, the formation of two azeotropes can be avoided, leading to a drastic simplification of downstream separation, requiring only one-step conventional distillation. By increasing the methanol conversion to 45%, the formation of a DMC-methanol azeotrope is prevented, and the in-situ water adsorption effectively avoids the DMC-water azeotrope. Based on these findings, further research should focus on identifying suitable materials and (reactive) adsorbents, while also incorporating a more detailed process layout and cycle design. These efforts will unlock the full potential of SEDMC synthesis in the production of renewable materials.