Synthesis Of Dimethyl Carbonate Research Articles

Direct Synthesis of Dimethyl Carbonate from Methanol and Carbon Dioxide Catalyzed by Cerium-Based High-Entropy Oxides

Direct Synthesis of Dimethyl Carbonate from Methanol and Carbon Dioxide Catalyzed by Cerium-Based High-Entropy Oxides

Vacancy-cluster-mediated ceria for efficient synthesis of dimethyl carbonate from CO2

Vacancy-cluster-mediated ceria for efficient synthesis of dimethyl carbonate from CO2

Selective synthesis of dimethyl carbonate via the coupling reaction of CO2 and alcohols by the synergistic catalysis of silver sulfadiazine and superbase

The three-component coupling of methanol, CO2 and propargyl alcohol to manufacture dimethyl carbonate (DMC) provides a new, thermodynamic favorable and green chemical synthesis route. In this work, to overcome the problems of low DMC yield and slow conversion rate of intermediates, the synergistic catalytic strategy of silver sulfadiazine and superbase is developed to improve the reaction efficiency. The effect of various parameters i.e. catalyst and cocatalyst types, catalyst loading, solvent, temperature, proportion of raw materials, pressure and time on the coupling reactions is investigated in detail. Under the optimal conditions, the selectivity of DMC is 89.5% with the yield of 55.6%. And the effect of alkyne derivative α-monosubstituted propargyl alcohol on the efficiency and selectivity of DMC are studied also. The mechanism study shows that propargyl alcohols with different structures apparently affect the reaction process, and the synergistic catalysis of silver sulfadiazine/1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) is the reason for the high yield and selectivity of DMC.

DFT Investigations of the Reaction Mechanism of Dimethyl Carbonate Synthesis from Methanol and CO on Various Cu Species in Y Zeolites

In this study, a density functional theory method is employed to investigate the reaction mechanisms of dimethyl carbonate (DMC) formation, through oxidative carbonylation of methanol, on four types of Y zeolites doped with Cu+, Cu2+, Cu2O and CuO, respectively. A common chemical route is found for these zeolites and identified as, first, the adsorbed CH3OH is oxidized to CH3O species; subsequently, CO inserts into CH3O to CH3OCO, which reacts with CH3O to form DMC rapidly; and finally, the adsorbed DMC is released into the gas phase. The rate-limiting step on Cu2+Y zeolite is identified as oxidation of CH3OH to CH3O with activation barrier of 66.73 kJ·mol−1. While for Cu+Y, Cu2O-Y and CuO-Y zeolites, the rate-limiting step is insertion of CO into CH3O, and the corresponding activation barriers are 63.73, 60.01 and 104.64 kJ·mol−1, respectively. For Cu+Y, Cu2+Y and Cu2O-Y zeolites, adsorbed CH3OH is oxidized to CH3O with the presence of oxygen, whereas oxidation of CH3OH on CuO-Y is caused by the lattice oxygen of CuO. The order of catalytic activities of these four types of zeolites with different Cu states follows Cu+Y ≈ Cu2O-Y > Cu2+Y > CuO-Y zeolite. Therefore, CuY catalysts with Cu+ and Cu2O as dominated Cu species are beneficial to the formation of DMC.

One-step DMC synthesis from CO2 under catalysis of ionic liquids prepared with 1,2-propylene glycol

Three quaternary ammonium ionic liquids with strong nucleophilicity and distinctive structures were synthesized with high yield and purity based on the 1,2-propylene glycol anion (CH3CH2OHCH2O-) derived from transesterification products. Dimethyl carbonate (DMC) was in turn produced via a one-step reaction among propylene oxide (PO), CO2, and methanol (MeOH) by using the synthesized ionic liquids. The involved two-stage catalytic reaction of PO-CO2 cycloaddition and PC-MeOH transesterification was implemented without catalyst separation. Under mild conditions, the PO conversion reached 99.0%, with a PC yield of 99.0%, and a TON value of 119.5. Following the cycloaddition, MeOH was immediately introduced to achieve a PC conversion of 71.2%, a selectivity to DMC above 99%, and a TON value of 57.4 for the transesterification reaction. The influences of temperature as well as time for cycloaddition and transesterification were investigated. Cycloaddition of CO2 with various epoxides was also examined and all showed good performance. By taking advantage of the decomposability of as-prepared ionic liquids and the recyclability of decomposition products, a new catalyst circulation process was designed to complete the full cycle without introduction of any impurities into the product system.

Hierarchical Catalysts Based on Cerium(IV) Oxide for Direct Synthesis of Dimethyl Carbonate

Hierarchical Catalysts Based on Cerium(IV) Oxide for Direct Synthesis of Dimethyl Carbonate

Zn‐Doped CeO2 Nanorods: a Highly Efficient Heterogeneous Catalyst for the Direct Synthesis of Dimethyl Carbonate from CO2 and Methanol

AbstractThe direct synthesis of dimethyl carbonate from methanol and CO2 is a green and sustainable processes. In this paper, a new type of Zn‐doped CeO2 nanorods catalyst was successfully prepared by a facile hydrothermal process, and characterized by a combination of techniques including XRD, Raman, HRTEM, SEM, N2‐sorption, CO2‐TPD, NH3‐TPD, XPS. The catalyst was employed as a catalyst for the synthesis of dimethyl carbonate from methanol and CO2. Catalytic results revealed that the Ce1Zn0.1Oδ nanorods catalyst demonstrated superior catalytic activity, affording a high DMC yield of 24.2 mmolDMC/gcat, which compared favorably to other previously reported catalysts. According to the XPS and CO2‐TPD measurements, in comparison with the pure CeO2 nanorods, the surface oxygen vacancies and weak basic sites can be systemically enriched by introducing optimal amount of Zn dopants into CeO2 to improve the catalytic activity for the reaction. This work establishes an efficient catalyst for the direct synthesis of dimethyl carbonate from CO2 and methanol.

Carbon template synthesis of CeO2 catalyst for direct conversion of methanol and carbon dioxide to dimethyl carbonate

Dimethyl carbonate (DMC) is an interesting, value added chemical and a high energy additive to fuels. In this study, several CeO2 catalysts were successfully synthesized through carbon template method using two renewable sources of activated carbon. The structure of catalysts was fully resolved by XRD, SEM, N2-adsorption, NH3-TPD, CO2-TPD and XPS. CeO2 catalysts prepared using coconut shell activated carbon (CAC) template exhibit better surface morphology and improved catalytic performance compared to walnut shell activated carbon (WAC)-supported catalysts. We demonstrated a correlation between the efficiency of DMC synthesis and the abundance of moderately acidic and moderately basic active sites on the catalyst. It was found that the presence of oxygen vacancies (Vo) facilitates carbonyl bond cleavage of CO2. The best-performing catalyst was 4% CeO2/CAC owing to the richest Vo and the optimum acid/base properties. Moreover, a plausible catalytic mechanism of DMC formation was proposed, and includes the interaction between methoxy carbonate (CH3OCO2−) formed with the aid of Vo and moderately basic sites and methyl cation (CH3+) formed on the moderately acidic sites.

Dimethyl carbonate synthesis from CO2 and methanol over CeO2: elucidating the surface intermediates and oxygen vacancy-assisted reaction mechanism

Oxygen vacancy-assisted reaction mechanisms and key surface intermediates were uncovered by operando spectroscopic and DFT-based molecular dynamics simulations in direct dimethyl carbonate (DMC) synthesis from CO2 and methanol over CeO2 catalyst.

Homogeneous base catalyst with high activity and stability for synthesis of dimethyl carbonate by transesterification.

In the synthesis of dimethyl carbonate (DMC) by transesterification, CH3ONa has been commonly applied as a homogeneous catalyst due to its high catalytic activity, but its stability is unsatisfactory. Here, by studying the influence of ionic liquid base strength on transesterification, we prepared an organic base catalyst, potassium imidazole (KIm), with high catalytic activity and stability, which solved the problem of catalyst deactivation in transesterification. The results showed that when KIm was used in the synthesis of DMC from propylene carbonate (PC) and methanol (MeOH), the chemical equilibrium could be reached within 3 minutes and the yield of DMC reached 73.03%, indicating that KIm performed better in transesterification than the majority of previously reported catalysts. In addition, the activity of the catalyst had hardly decreased after ten cycles of reaction, which can well meet the requirements of industrial production.

Efficient and stable catalysts for the synthesis of dimethyl carbonate by carbonylation of methyl nitrite applying the starch-coated activated carbon as a support

For the synthesis of dimethyl carbonate (DMC) by carbonylation of methyl nitrite (MN), the lack of efficient and stable catalysts is a crucial factor limiting the application of this technology.

Surface species in direct liquid phase synthesis of dimethyl carbonate from methanol and CO2: an MCR-ALS augmented ATR-IR study.

The reaction mechanism of dimethyl carbonate (DMC) production over ZrO2 from CO2 and CH3OH is well-known, but the level of understanding has not improved in the last decade. Most commonly, the reaction mechanism has been explored in the gas phase, whilst DMC production occurs in the liquid phase. To overcome this contradiction, we exploited in situ ATR-IR spectroscopy to study DMC formation over ZrO2 in the liquid phase. A multiple curve resolution-alternate least square (MCR-ALS) approach was applied to spectra collected during the CO2/CH3OH interaction with the catalyst surface, leading to the identification of five pure components with their respective concentration profiles. CO2 and CH3OH activation to carbonates and methoxide species was found to strongly depend on the reaction temperature. Low temperature prevents methanol dissociation leaving a catalyst covered with stable carbonates, whilst higher temperature decreases the stability of the carbonates and enhances the formation of methoxides. A reaction path involving the methoxide/carbonate interaction at the surface was observed at low temperature (≤50 °C). We propose that a different reaction path, independent of carbonate formation and involving the direct CO2/methoxide interplay, occurs at 70 °C.

Microscopic mechanism study and process optimization of dimethyl carbonate production coupled biomass chemical looping gasification system

Biomass chemical looping gasification technology is one of the essential ways to utilize abundant biomass resources. At the same time, dimethyl carbonate can replace phosgene as an environment-friendly organic material for the synthesis of polycarbonate. In this paper, a novel system coupling biomass chemical looping gasification with dimethyl carbonate synthesis with methanol as an intermediate is designed through microscopic mechanism analysis and process optimization. Firstly, reactive force field molecular dynamics simulation is performed to explore the reaction mechanism of biomass chemical looping gasification to determine the optimal gasification temperature range. Secondly, steady-state simulations of the process based on molecular dynamics simulation results are carried out to investigate the effects of temperature, steam to biomass ratio, and oxygen carrier to biomass ratio on the syngas yield and compositions. In addition, the main energy indicators of biomass chemical looping gasification process including lower heating value and cold gas efficiency are analyzed based on the above optimum parameters. Then, two synthesis stages are simulated and optimized with the following results obtained: the optimal temperature and pressure of methanol synthesis stage are 150 °C and 4 MPa; the optimal temperature and pressure of dimethyl carbonate synthesis stage are 140 °C and 0.3 MPa. Finally, the pre-separation-extraction-decantation process separates the mixture of dimethyl carbonate and methanol generated in the synthesis stage with 99.11% purity of dimethyl carbonate. Above results verify the feasibility of producing dimethyl carbonate from the perspective of multi-scale simulation and realize the multi-level utilization of biomass resources.

Cerium doped Zr-based metal-organic framework as catalyst for direct synthesis of dimethyl carbonate from CO2 and methanol

The disadvantage of Ce/Zr metal oxide as catalyst for direct synthesis dimethyl carbonate (DMC) from CO2 and methanol is low DMC formation rate because of its low specific surface area and active sites. In this work, it can be improved by highly uniform dispersion cerium doped Zr-based metal-organic frameworks (UiO-66 MOFs), which were synthesized via a modified hydrothermal method. The as-prepared catalysts have been extensively characterized using XRD, BET, FT-IR, SEM, TEM, TGA, NH3-TPD, CO2-TPD, XPS techniques. Experimental evaluation results indicated that the highly uniform dispersed Ce-doped UiO-66 MOFs exhibited markedly improved catalytic performance than traditional Ce/Zr metal oxide catalyst. The highest yield of DMC catalyzed by Ce-UiO-66–2 was 0.295% (reaction time was 12 h; reaction temperature was 140 °C; reaction pressure was 11 MPa). Then, it was found that doping of Ce atoms into the zirconium lattice to produce UiO-66 MOFs could effectively increase the number of acidic and medium basic sites than UiO-66 (none Ce), thus could greatly enhance the catalytic performance. Moreover, using 2-cyanopyridine as dehydrating agent, the DMC yield could be further raised greatly. Last, based on reported literature and our results, a possible reaction mechanism over Ce-UiO-66-X was proposed.

Atom-Economical Synthesis of Dimethyl Carbonate from CO2 : Engineering Reactive Frustrated Lewis Pairs on Ceria with Vacancy Clusters.

The chemical conversion of CO2 to long-chain chemicals is considered as a highly attractive method to produce value-added organics, while the underlying reaction mechanism remains unclear. By constructing surface vacancy-cluster-mediated solid frustrated Lewis pairs (FLPs), the 100 % atom-economical, efficient chemical conversion of CO2 to dimethyl carbonate (DMC) was realized. By taking CeO2 as a model system, we illustrate that FLP sites can efficiently accelerate the coupling and conversion of key intermediates. As demonstrated, CeO2 with rich FLP sites shows improved reaction activity and achieves a high yield of DMC up to 15.3 mmol g-1 . In addition, by means of synchrotron radiation in situ diffuse reflectance infrared Fourier-transform spectroscopy, combined with density functional theory calculations, the reaction mechanism on the FLP site was investigated systematically and in-depth, providing pioneering insights into the underlying pathway for CO2 chemical conversion to long-chain chemicals.

Atom‐Economical Synthesis of Dimethyl Carbonate from CO2: Engineering Reactive Frustrated Lewis Pairs on Ceria with Vacancy Clusters

AbstractThe chemical conversion of CO2to long‐chain chemicals is considered as a highly attractive method to produce value‐added organics, while the underlying reaction mechanism remains unclear. By constructing surface vacancy‐cluster‐mediated solid frustrated Lewis pairs (FLPs), the 100 % atom‐economical, efficient chemical conversion of CO2to dimethyl carbonate (DMC) was realized. By taking CeO2as a model system, we illustrate that FLP sites can efficiently accelerate the coupling and conversion of key intermediates. As demonstrated, CeO2with rich FLP sites shows improved reaction activity and achieves a high yield of DMC up to 15.3 mmol g−1. In addition, by means of synchrotron radiation in situ diffuse reflectance infrared Fourier‐transform spectroscopy, combined with density functional theory calculations, the reaction mechanism on the FLP site was investigated systematically and in‐depth, providing pioneering insights into the underlying pathway for CO2chemical conversion to long‐chain chemicals.

Integrated DFT and experimental study on Co3O4/CeO2 catalyst for direct synthesis of dimethyl carbonate from CO2

The oxygen deficient site on the catalyst has a strong impact on the activation of CO2 for the synthesis of dimethyl carbonate (DMC). The Co3O4/CeO2 catalyst exhibits multiple reduction behavior as cobalt metal species differ in the strength of their interaction with CeO2. This causes the surface reduction from Ce4+ to Ce3+ in solid solution Co-O-Ce. The dispersion of Co3O4 enhanced the formation of oxygen deficient site as revealed by XPS, CO2-chemisorption and TPR. The non-precious Co3O4/CeO2 nanorod was recognized as a potential catalyst for promoting Ce4+ to Ce3+ for CO2 activation and dimethyl carbonate synthesis (81.5% of yield). Energetics of oxygen vacancy formation of low index surfaces of CeO2 was determined with first-principles calculations based on DFT. Results disclosed the Ce4+ to Ce3+ formation energy of CeO2 due to Co substitution and corroborated the experimental results. Further, calculations provide the details of the effect of Co substitution on the electronic structure of reduced CeO2 surfaces. Estimated CO2 adsorption energy indicates (110) as the most active surface for activation of CO2.

Dimethyl Carbonate Synthesis via Transesterification of Propylene Carbonate Using a Titanium–Praseodymium-Based Catalyst

Dimethyl Carbonate Synthesis via Transesterification of Propylene Carbonate Using a Titanium–Praseodymium-Based Catalyst

An Intensified Green Process for the Coproduction of DMC and DMO by the Oxidative Carbonylation of Methanol

Dimethyl carbonate (DMC) is an eco-friendly and sustainable compound with widespread industrial applications. Various extensive routes have been exploited in the chemical industry to produce DMC. However, these routes have several environmental and energy drawbacks. In this study, a promising novel industrial scheme for the synthesis of DMC via the oxidative carbonylation of vaporized methanol with dimethyl oxalate (DMO) as a byproduct is investigated. A methanol conversion of 81.86% and a DMC selectivity of 83.47% were achieved using an isothermal fixed-bed reactor at 130 °C. The DMC is withdrawn at a purity of >99 mol% via pressure-swing azeotropic distillations. Heat integration was performed to optimize energy consumption, reducing the energy requirements by 28%. An economic evaluation was performed for estimating the profitability via cash-flow diagrams, predicting a payback period of 3.7 years. The proposed green process exhibits several benefits, including high profitability and being environmentally friendly. It also eliminates the use or production of hazardous materials, and it enhances safety characteristics.

The role of Ce doping on the activity of La2O2CO3 nanosheets catalysts in synthesis of dimethyl carbonate from propylene carbonate and methanol

Dimethyl carbonate (DMC) production from the transesterification reaction of propylene carbonate (PC) and methanol is an eco-friendly and economical process with propylene glycol (PG) as the high value-added co-product. We report herein the synthesis of Ce-doped La2O2CO3 nanosheets (La1Cex) with varying Ce contents through a solvothermol method. La1Ce0.15 catalyst exhibits superior catalytic performance in the production of DMC by the transesterification of methanol and PC. A remarkable improvement in PC conversion (> 85%) and DMC selectivity (> 98%) can be attributed to an increase in surface O2− base sites caused by increased oxygen interstitials and vacancies through Ce doping.