One-pot Synthesis Of Dimethyl Carbonate Research Articles

One-Pot Synthesis of Dimethyl Carbonate over a Binary Catalyst of an Ionic Liquid and an Alkali Carbonate under Low Pressure.

A mild and highly efficient approach has been developed for the one-pot synthesis of dimethyl carbonate (DMC) from epoxide, carbon dioxide, and methanol under low initial pressure. The key to the successful transformation is the use of a bicomponent catalytic system composed of a hydroxyl-functionalized ionic liquid and an alkali carbonate. This bicomponent catalytic system demonstrated excellent reusability in four runs. Under the optimal reaction conditions, a 64% yield of DMC from propylene oxide and an 81% yield of DMC from ethylene oxide were obtained.

The role of Zn in the sustainable one-pot synthesis of dimethyl carbonate from carbon dioxide, methanol and propylene oxide

Dimethyl carbonate (DMC) can be applied as a greener alternative to more hazardous materials, e.g. phosgene or dimethyl sulfate. Herein, one-pot synthesis of DMC from propylene oxide, methanol and CO2 using alkali halide catalysts under mild conditions was studied. Addition of Zn powder to the K2CO3-NaBr-ZnO catalyst system was seen to increase DMC selectivity from 19.8% (TOF = 39.0 h−1) to 40.2% (TOF = 78.1 h−1) at 20 bar and 160 °C for 5 h. Catalyst characterisation showed that Zn powder increases the stability of the catalyst, preventing the active ingredients on the catalyst surface from leaching. An increase in propylene oxide conversion to DMC is attributed to the increase of Zn2+ ions in the reaction solution. Elevated pressure was not found to be a necessary reaction condition for transesterification. This study shows that increased selectivity to DMC can be achieved at mild conditions with the addition of Zn powder.

K/Al-doped ZnO nanocomposite as bifunctional catalyst for photocatalysis and synthesis of dimethyl carbonate

In this paper, K/Al-doped ZnO nanocomposite was prepared by coprecipitation and impregnation method using sodium hydroxide as precipitation agent. The title material was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible spectroscopy (UV–Vis), Brunauer-Emmett-Teller (BET) and temperature-programmed desorption of carbon dioxide (CO2-TPD). K/Al-doped ZnO as photocatalyst exhibits highly efficient photocatalytic performance for degradation of four typical dyes (Methylene blue (MB), Congo red (CR), Rhodamine B (RhB) and Methyl orange (MO)) under UV-light irradiation. The photocatalytic decomposition rate in the order of CR (91.40%) > MB (82.47%) > RhB (54.96%) > MO (51.70%). The comparative experiments show that K/Al-doped ZnO composite possesses higher activity relative to ZnO, Al2O3 and Al-doped ZnO. Furthermore, the composite also has unique catalytic behavior for the one-pot synthesis of dimethyl carbonate (DMC) from methanol (MeOH), epoxy propane (PO) and CO2, which may be an effective and simple material to one-pot synthesize DMC in industry.

Preparation of highly stable Ca-Zn-Al oxide catalyst and its catalytic performance for one-pot synthesis of dimethyl carbonate

Ca-Zn-Al oxide was prepared by co-precipitation method and the effect of preparation conditions on its catalytic performance was investigated. The Ca-Zn-Al oxide exhibited an excellent catalytic activity and stability for one-pot synthesis of dimethyl carbonate (DMC) from urea, 1,2-propylene glycol (PG), and methanol. XRD characterization and activity evaluation results indicated that new crystalline phases Ca3Al4ZnO10 and ZnAl2O4 could create a synergistic effect with CaO and ZnO, being responsible for the excellent catalytic performance of Ca-Zn-Al oxide. Response surface methodology (RSM) was used to investigate the effect of operating variables and to optimize conditions for the first-step reaction of PG and urea to propylene carbonate. Then the effect of reaction conditions for the transesterification of propylene carbonate with methanol to DMC was also investigated. As a result, a DMC yield of 84.7% was obtained under the appropriate reaction conditions. The Ca-Zn-Al oxide could be reused for four times without a significant change in its catalytic activity.

Low pressure one-pot synthesis of dimethyl carbonate catalyzed by an alkali carbonate

A mild and efficient protocol for the alkali carbonate-catalyzed one-pot synthesis of dimethyl carbonate (DMC) from epoxide, CO2 and methanol was developed. The reaction conditions for the one-pot synthesis of DMC were investigated. Under the optimized conditions of initial pressure 0.5 MPa, 120 °C and catalyst loading of 7.5 mol%, 63.5% yield of DMC was achieved using ethylene oxide as the starting material. A mechanism for the catalysis by the alkali carbonate was proposed.

Preparation of Ca–Zn–Al Oxides and Their Catalytic Performance in the One-Pot Synthesis of Dimethyl Carbonate from Urea, 1,2-Propylene Glycol, and Methanol

A series of Ca–Zn–Al oxides were prepared by different methods and their structures, compositions, and basicities were characterized by means of X-ray diffraction (XRD), N2 adsorption–desorption, inductively coupled plasma-atomic emission spectrometry (ICP-AES), and CO2 temperature-programmed desorption (TPD). CO2 TPD analysis showed that all of the prepared Ca–Zn–Al oxides had both weak base sites and strong base sites, but their base amounts were different. The weak base sites were provided by the Zn–Al oxides, whereas the strong base sites were due to CaO. Ca–Zn–Al oxides with different base distributions could be prepared by varying the molar ratios of Zn/Al and Ca/Al. The Ca–Zn–Al oxides showed excellent catalytic performances for the one-pot synthesis of dimethyl carbonate (DMC) from urea, 1,2-propylene glycol (PG), and methanol: The yield of DMC could reach 82.9% under appropriate reaction conditions. However, the catalytic performance of the recovered catalyst decreased dramatically, mainly becaus...

Direct synthesis of dimethyl carbonate and propylene glycol using potassium bicarbonate as catalyst in supercritical CO2

Abstract The improved one-pot synthesis of dimethyl carbonate and propylene glycol from propylene oxide, supercritical carbon dioxide, and methanol with potassium bicarbonate as the catalyst has been reported in this paper. As far as we know, it is the first time to use potassium bicarbonate only as the catalyst in the production process which is simple and cheap. Satisfactory conversion rate of propylene oxide and yield of the products could be achieved at the optimized conditions with quite a small amount of by-products. Our new method offers an attractive choice for the production of dimethyl carbonate in large-scale industry efficiently and environmental friendly.

One-pot synthesis of dimethyl carbonate from carbon dioxide, cyclohexene oxide, and methanol

Dimethyl carbonate (DMC) and 1,2-cyclohexanediol (CHD) were directly synthesized by using K2CO3 from cyclohexane oxide (CHO), CO2, and CH3OH. K2CO3 and corresponding potassium-based catalysts were explored in the reaction system for the first time. The reaction was controlled by two mechanisms (the direct alkoxide and polymer dissociation mechanisms) under different reaction temperatures. The best catalytic performance with 95.7 % CHO conversion and a maximum of Y DMC and Y CHD were 55.4 and 63.4 %, respectively, which were obtained using K2CO3 as the catalyst under optimized reaction conditions. This approach is effective for producing DMC and CHD due to its easy operation, fewer hybrid ion introductions, and low cost of the catalyst.

One-Pot Synthesis of Dimethyl Carbonate over Basic Zeolite Catalysts

One-pot synthesis of dimethyl carbonate (DMC) from methanol, propylene oxide (PO) and carbon dioxide has been investigated using the basic zeolites as catalysts. Among the zeolites studied, Beta showed the best catalytic performance for DMC production. That the desilication of zeolite structure resulted in a hierarchical porosity of Beta, leading to more amount of KOH can be loaded on the surface of zeolite and therefore enhancing the base strength of the catalyst was proposed to be the reason for improved catalytic performance.

An Improved One-Pot Synthesis of Dimethyl Carbonate from Propylene Oxide, CO2 and Methanol

The direct synthesis of dimethyl carbonate (DMC) and propylene glycol from propylene oxide, CO2 and methanol has been studied with potassium carbonate as catalyst. This is the first time that K2CO3 which is readily available has been used as a catalyst. It is quite simple and cheap to use. This route may be an effective way of producing DMC on the large-scale. DMC is used in polycarbonate synthesis, polyurethane synthesis, carbonylating reagents, alkylating reagents, polar solvents, octane boosters in gasoline, carbon-particle reducing agents for diesel engines It is a safe and environmentally benign alternative for phosgene in some reactions.

One-Pot Synthesis of Dimethyl Carbonate from Methanol, Propylene Oxide and Carbon Dioxide Over Supported Choline hydroxide/MgO

A basic ionic liquid, namely choline hydroxide, was prepared and supported on MgO to form Choline hydroxide/MgO material. The supported ionic liquid material was characterized by XRD, FT–IR and TG and used as a catalyst in one-pot synthesis of dimethyl carbonate from propylene oxide, methanol and carbon dioxide. A good catalytic performance was obtained with 98% conversion of epoxide and selectivity of above 90% to DMC + PC over the composite catalyst. However, the catalyst could be reused three times without a significant change in its catalytic activity.

Mesoporous smectites incorporated with alkali metal cations as solid base catalysts

A series of magnesium containing mesoporous smectites incorporated with alkali hydroxide (NaOH, KOH or LiOH) has been prepared and employed for such base-catalyzed model reactions as transesterification of ethyl acetate with methanol, Knoevenagel condensation of benzaldehyde with ethyl cyanoacetate and one-pot synthesis of dimethyl carbonate (DMC) from propylene oxide, carbon dioxide and methanol. The effects of the quantity and kind of the incorporated alkali atoms on the catalytic properties of the smectites were investigated. Characterization of the smectites has shown that the incorporation of alkali atoms reduces their surface area and total pore volume but enhances the amount and strength of their basic sites. The product yield of the transesterification was increased with the content of alkali atoms incorporated. It has been suggested that the moderately basic sites are responsible for this reaction. The yield of the Knoevenagel reaction depends little on the alkali atom content. Increasing the content of alkali atoms causes the increase in the DMC yield of the one-pot synthesis and the decrease in the yield of methanolysis of propylene oxide, which is the side reaction of the one-pot synthesis. The incorporation of Li was less effective than Na and K for the one-pot reaction. The structures of basic sites over the alkali-incorporated smectites have been discussed.

One-Pot Synthesis of Dimethyl Carbonate Catalyzed by [bmim]BF4/CH3ONa

Abstract The one-pot synthesis of dimethyl carbonate from propylene oxide, carbon dioxide, and methanol was investigated. The catalyst adopted was a mixture of 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF 4 ) and sodium methoxide. Under the reaction conditions of 4 MPa, 5 h, and 150°C, the conversion of propylene oxide was above 95%, and the selectivity for propylene carbonate was 87.1%. More importantly, the yield of dimethyl carbonate reached 67.6%, which is higher than the results of the previous literature using the one-pot synthesis method.

One-pot synthesis of dimethyl carbonate catalyzed by n-Bu 4NBr/ n-Bu 3N from methanol, epoxides, and supercritical CO 2

A homogeneous binary catalyst system, n-Bu 4NBr/ n-Bu 3N, was found to be active for the synthesis of dimethyl carbonate from styrene oxide (SO), methanol, and supercritical CO 2. Under the optimized conditions, the dimethyl carbonate yield could reach 84% at SO conversion of 98%. Several parameters were studied, i.e. catalyst precursors, reaction time and temperature, methanol/epoxide feed ratio in moles, and CO 2 pressure. The best compromise for the one-pot synthesis was achieved with an equimolar amount of n-Bu 4NBr/ n-Bu 3N. A possible mechanism for the present n-Bu 4NBr/ n-Bu 3N-catalyzed one-pot synthesis of dimethyl carbonate was proposed.

Kinetic Study on the One-Pot Synthesis of Dimethyl Carbonate in Supercritical CO2 Conditions

The kinetics of one-pot synthesis of dimethyl carbonate (DMC) was investigated using ethylene epoxide (EO), methanol, and CO2 as raw materials and a mixture of KI and K2CO3 as a catalyst under supercritical CO2 conditions. The reaction pathway of the one-pot process is that EO first reacts with CO2 to form ethylene carbonate (EC) and then EC reacts with methanol to produce DMC and ethylene glycol (EG). EC formation is a relatively fast reaction, whereas the transesterification of EC with methanol to form DMC is a relatively slow reaction and the rate-control step of the one-pot synthesis. 2-Methoxyethanol (ME), which is the exclusive byproduct, is predominantly formed by the reaction of EC with methanol. An isothermal kinetics model and an isobaric kinetics model for the one-pot synthesis of DMC were developed. The relative standard deviations of the models from the experiment data were less than ±15% and ±10%, respectively. The effects of temperature and CO2 density on the reaction rates and selectivity ...

One-pot synthesis of dimethyl carbonate and glycols from supercritical CO 2, ethylene oxide or propylene oxide, and methanol

Direct syntheses of dimethyl carbonate (DMC) and glycols (GCs) from supercritical (SC) CO 2, epoxides (propylene oxide or ethylene oxide), and methanol were carried out using different solid catalysts prepared in this work. The effects of various conditions, such as reaction temperature, pressure, reaction time, molar ratio of the reactants, and the properties of the supports of the catalysts, on the conversion and yields were investigated. KI supported on ZnO (KI/ZnO) and KI/ZnO with K 2CO 3 (K 2CO 3-KI/ZnO) were very active and selective for the reaction after calcinations. At 423 K, all epoxides were reacted in 4 h; the yields of DMC and GC exceeded 57% when ethylene oxide was used, and the amount of the by-products was very small (0.2%). The K 2CO 3-KI/ZnO could be reused four times, and the yield and selectivity remained unchanged. No leaching of the active catalyst components was detectable at the experimental conditions, probably because the reaction was conducted in homogenous supercritical conditions, where non-corrosive CO 2 was the main component in the reaction mixture. A mechanism of the reaction was proposed on the basis of the experimental results. This route may be an effective way to produce DMC and glycols in large-scale because it is simple, the raw materials are cheap, and the amount of by-products is very small.

One-Pot Synthesis of Dimethyl Carbonate Using Ethylene Oxide, Methanol, and Carbon Dioxide under Supercritical Conditions

The synthesis of dimethyl carbonate (DMC) from ethylene oxide (EO), methanol, and carbon dioxide was investigated. In the proposed one-pot synthesis of DMC, the reaction of EO with CO2 was coupled simultaneously with the reaction of ethylene carbonate with methanol under reaction conditions at which carbon dioxide was in supercritical state. The catalysts were experimentally screened at temperatures from 80 to 140 °C and pressures from 5.0 to 15.0 MPa. The mixture of KI and K2CO3 showed the highest catalytic activity for the one-pot DMC synthesis. The preferential weight ratio of KI to K2CO3 in the mixed catalyst ranges from 1:3 to 5:3. The effects of the reaction conditions, such as catalyst concentration, temperature, pressure, reaction time, and reactant compositions, were experimentally studied. High temperature favors the formation of the desired products, DMC and ethylene carbonate. The effect of pressure on the DMC yield is not significant. A high EO content in the feed is beneficial to increasing the selectivity of the desired products. Using the mixture of KI and K2CO3 (weight ratio of KI/K2CO3 = 1:1) as the catalyst with a molar ratio of catalyst to EO of 0.05, the DMC selectivity can reach above 73.0% at 100.0% EO conversion with less than 4.0% selectivity of the byproduct 2-methoxyethanol at the appropriate reaction conditions.

Synthesis of dimethyl carbonate and glycols from carbon dioxide, epoxides, and methanol using heterogeneous basic metal oxide catalysts with high activity and selectivity

This paper gives a comprehensive report on a two-step synthesis of dimethyl carbonate (DMC) from epoxides, carbon dioxide and methanol using various basic metal oxide catalysts. The first step is the reaction of ethylene oxide or propylene oxide with CO 2 to form the corresponding cyclic carbonates, and the second step is the transesterification reaction of the cyclic carbonates with methanol to DMC and glycols. Among the catalysts examined, MgO is the most active and selective for both these reactions. Other alcohols can be used for the second step, but the activity decreases as the carbon number of the alcohol increases. Although a one-pot synthesis of DMC, i.e. the sequential reaction of the epoxide, CO 2 and methanol, is also possible with MgO, the selectivity is low because of the alcoholysis of the epoxide. In contrast with the reactions of ethylene oxide and propylene oxide, when styrene oxide is used for the first reaction and for the one-pot synthesis, mandelic acid is produced. Basic properties of the metal oxide catalysts were measured by temperature programmed desorption of CO 2. The relationship between the catalytic performance and the basic property is discussed.