Synthesis Of Propylene Carbonate Research Articles

Preparation of Schiff base metal catalyst and its catalytic synthesis of propylene carbonate from CO2

In recent years, research on the conversion of CO2 into fine chemical products has emerged as a prominent and dynamic area of study. In this study, four ligands were synthesized using salicylaldehyde, o-phenylenediamine, ethylenediamine, hexanediamine, and 2,6-diaminopyridine as precursors. Subsequently, these ligands were reacted with cobalt nitrate, zinc chloride, and aluminum chloride to synthesize 12 Schiff base metal complexes, which were employed as catalysts for the synthesis of propylene carbonate from CO2 and epichlorohydrin. The findings reveal that the SF-L/Co catalyst demonstrated superior performance, potentially attributed to the robust chelating capability of Co, leading to the provision of more acidic metal centers. Characterization of SF-L/Co was conducted utilizing scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) techniques. Process conditions were optimized, resulting in the achievement of a 100% yield and selectivity of propylene carbonate under optimal reaction conditions, without the generation of any by-products. Furthermore, the catalyst exhibited remarkable reusability, demonstrating consistent catalytic activity over five successive cycles without a substantial decrease in performance.

Review on the recent advances in catalytic conversion of carbon dioxide for synthesis of cyclic propylene carbonate

Generation of carbondioxide in the atmosphere has increased considerably over the past decades due to the increase of industrialization. This led to the increase in the global temperature which affects the eco-system. It is essential to reduce the emission of carbondioxide in the atmosphere for which different researchers are working on re-utilization of the generated carbondioxide either by converting to different products or by trapping them as carbonates. Propylene carbonate is one of the chemicals that are synthesized by using CO2 as a reactant. Propylene carbonate has many applications as an end product and acts as intermediate for synthesis of other useful chemicals. Fixation of CO2 into propylene oxide for the synthesis of propylene carbonate is still a challenging task due to the high thermodynamic stability of CO2. Propylene carbonate can be synthesized by reacting CO2 with different high energy materials using different catalyst. This review is focused on providing an idea about different types of catalyst reported for synthesis of cyclic propylene carbonate using propylene oxide and propylene glycol as the starting materials. This review also provides the mechanism for conversion of CO2 to propylene carbonate by different catalyst and at various working conditions.

Oxidative carbonylation of propylene glycol to propylene carbonate by copper-based catalysts

BackgroundDevelopment of copper-based catalyst and associated reaction engineering for heterogeneous oxidative carbonylation of propylene glycol (PG) to optimize conversion and selectivity. Coupling reactions with reverse water-gas shift reaction is a good way of realizing CO2 utilization. MethodThe synthesis of propylene carbonate (PC) through the oxidative carbonylation of propylene glycol is carried out in a pressurized autoclave reactor using solid copper catalysts. Various types of copper and composite copper/ceria catalysts are prepared by coprecipitation or impregnation method. Significant findingsReaction temperature and the roles of sodium acetate (SA) and potassium iodide (KI) additives are systematically studied with pure copper to map out the optimum reaction condition, i.e., a 100 °C-reaction using 2.0 g of PG mixed with 8.0 g of solvent with 0.02 g of SA and 0.02 g of KI additives. Using this optimized condition, the copper and composite copper/ceria catalysts are investigated with the composite catalysts composed of metallic copper on ceria, showing the highest selectivity of 94.7% towards PC. These findings in this study should pave way for the development of practical industrial scale CO2 utilization processes.

Hydrotalcite-calcined derivatives doped by zinc: A nucleophile-modified multifunctional catalyst for synthesis of propylene carbonate by cycloaddition

The composition of hydrotalcite-calcined derivatives doped by Zinc was optimized by uniform design. This derivatives further modified by KI nucleophile promoted the catalytic performance in terms of activity, selectivity and stability. N,N-dimethylformamide was proved to be the best solvent for the cycloaddition through molecular simulation. The results of characterization showed that KI-modified derivatives had hydrotalcite phase and ZnO phase, and the elements with catalytic activity were uniformly dispersed. The specific surface area of the derivatives was greatly increased after proper calcination, and it's positively correlated with the cycloaddition activity.The derivatives had acidic-basic properties, and the catalytic mechanism was proposed accordingly.

Efficient Propylene Carbonate Synthesis from Urea and Propylene Glycol over Calcium Oxide-Magnesium Oxide Catalysts.

A series of calcium oxide-magnesium oxide (CaO-MgO) catalysts were prepared under the effects of different precipitating agents and using varied Mg/Ca ratios. The physiochemical characteristics of the prepared catalysts were analyzed using XRD, FE-SEM, BET, FTIR, and TG/DTA techniques. Quantification of basic active sites present on the surface of the CaO-MgO catalysts was carried out using the Hammett indicator method. The as-prepared mixed oxide samples were tested for propylene carbonate (PC) synthesis through the alcoholysis of urea with propylene glycol (PG). The effects of the catalyst composition, catalyst dose, reaction temperature, and contact time on the PC yield and selectivity were investigated. The maximum PC yield of 96%, with high PC selectivity of 99% and a urea conversion rate of 96%, was attained at 160 °C using CaO-MgO catalysts prepared using a Mg/Ca ratio of 1 and Na2CO3 as a precipitating agent. The best-performing catalysts also exhibited good reusability without any significant loss in PC selectivity. It is expected that the present study will provide useful information on the suitability of different precipitating agents with respect to the catalytic properties of the oxides of Ca and Mg and their application in the synthesis of organic carbonates.

A continuous process for cyclic carbonate synthesis from CO2 catalyzed by the ionic liquid in a microreactor system: Reaction kinetics, mass transfer, and process optimization

The reaction of CO2 and propylene oxide (PO) for the synthesis of propylene carbonate (PC) is an important reaction, but the reaction is generally carried out under high-temperature and high-pressure conditions due to the limitations of reaction kinetics and mass transfer. Here, we propose a novel microreaction system catalyzed by ionic liquids (ILs). The reaction processes (e.g., catalyst, temperature, pressure, gas–liquid flow rate, catalyst concentration, residence time) were optimized within microreactors of different inner diameters. The kinetics for carbonate synthesis with CO2 catalyzed by ionic liquid (IL-[HMIM]Br) in a microreactor was evaluated, and the activation energy of [HMIM]Br was obtained. Based on the rough numerical estimation of mass transfer characteristics, coupled with the reaction characteristics, the microreactor enhancement can reduce the reaction time for this fast reaction to minutes, typically several hours in conventional reactors. This provides new opportunities for enhancing gas–liquid reactions with typical mass transfer control and for CO2 utilization to achieve carbon neutrality.

Preparation of propylene carbonate by alcoholysis of urea from the perspective of homogeneous reaction: Influence of dissolution and precipitation of metal oxide catalysts

AbstractThe dissolution process of metal oxide catalysts in the alcoholysis of urea by 1, 2‐propylene glycol (PG) to the synthesis of propylene carbonate (PC) was investigated. It was found that the reaction was mainly catalyzed by homogeneous catalysts. The metal oxide reacted with ammonia and isocyanate acid, the decomposition products of urea, to form a complex and dissolved into the reaction system. The dissolved amount of catalyst was positively correlated with the PC yield by using different oxides and salts as catalysts. The Fourier‐transform infrared spectroscopy (FTIR) result of the catalysts reacting with urea showed that the dissolution‐precipitation process of the catalysts was related to the decomposition of urea. The results of catalytic test indicated that both the dissolved amount of catalysts and the structure of the complex affected PC yields. A reaction mechanism was proposed based on the results. From the mechanism, a complex catalyst with at least two ammonia ligands is better for this reaction.

Novel MOF catalysts based on calix[4]arene for the synthesis of propylene carbonate from propylene oxide and CO2

In this study, novel composite materials based on calix[4]arene with hydroxyl groups in the arene “bowl” (K-OH) and the aluminum(III) 2-aminoterephthalate metal organic framework (NH2-MIL-101(Al), MIL) have been synthesized according to in situ or “bottle around ship” strategy. The effect of the synthesis method, i.e., MW-assisted technique (MW) and the solvothermal procedure (Solv), on the structural, morphological, textural and catalytic properties of MIL/K-OH composites was demonstrated. Catalytic performance of the MIL/K-OH(MW) and MIL/K-OH(Solv) composites was studied in solvent-free coupling of CO2 and propylene oxide (PO) to produce propylene carbonate (PC) at 0.8 MPa of CO2 and 80 °C. The activity of the MIL/K-OH(Solv) catalyst was higher in comparison with MIL/K-OH(MW) material as a result of the differences in the textural properties. The binary system MIL/K-OH(MW)/[n-Bu4N]Br was demonstrated to be a promising catalyst for cycloaddition of CO2 to PO. In its presence, the conversion of PO was 77 % with 99 % selectivity towards PC at 1.2 MPa of CO2, 50 °C for 24 h.

Kinetic study of CO2 fixation into propylene carbonate with water as efficient medium using microreaction system

Carbon dioxide (CO 2 ) utilization and fixation have become one of the most important research areas nowadays due to the increase of global greenhouse effect. Cyclic carbonate, which is widely used in various fields, can be synthesized by fixation of CO 2 with epoxide in industry. Moreover, the synthesis of cyclic carbonate is a 100% atom economical reaction, which makes it eco-friendly and promising. To enhance the reaction efficiency and safety, a microreaction system was used as the platform for cycloaddition reaction. In this work, tetrabutylammonium bromide (TBAB) was chosen as catalyst, and propylene oxide (PO) as a mode substrate. Interestingly, the addition of water can increase the propylene carbonate (PC) yield and decrease the activation energy considerably, proving water as catalyst promoter for PC synthesis. PC yield and selectivity could reach 91.6% and 99.8%, respectively. The Influence factors and kinetic equation for CO 2 cycloaddition were obtained as well.

A novel supported ionic liquid membrane reactor for catalytic CO2 conversion

Converting CO2 into cyclic carbonates is one of the most promising ways to help mitigate global climate change. In this paper, we developed a novel supported ionic liquid membrane (SILM) that integrates reaction and gas permeation functions into a single unit for efficient synthesis of propylene carbonate (PC) under solvent-free, cocatalyst-free, and catalyst-free separation conditions. The catalytic stability of SILM was verified by batch experiments, and the structure, morphology and composition were characterized by XRD, SEM, and EDS. Also, the process parameters of continuous membrane catalysis were evaluated for PO conversion, PC selectivity, space-time yield and PO flux. By comparative analysis, polyvinylpyrrolidone (PVP) could not only effectively inhibit the loss of ionic liquid (IL), but also help to form a stable membrane layer. Characterization results confirmed that IL was basically concentrated in the top layer of γ-Al2O3 rather than the intermediate layer. Besides, the essential factors were identified to provide a feasible route for the large-scale conversion of CO2.

Tuning the catalytic properties for cycloaddition of CO2 to propylene oxide on zeolitic-imidazolate frameworks through variation of structure and chemical composition

A series of Zn- and Co containing zeolitic-imidazolate frameworks (ZIFs), such as ZIF-8(Zn)/ZIF-67(Co), MAF-5(Zn)/MAF-5(Co), and MAF-6(Zn)/MAF-6(Co), were investigated as catalysts for the synthesis of propylene carbonate (PC) from propylene oxide (PO) and CO2. The effect of the chemical composition, textural, structural and physicochemical properties on their activity was investigated. It was found that the activity of Zn-containing materials was higher in comparison with Co-based materials. Moreover, the yield of a PC was decreased with increasing Co content in structure of mixed Zn,Co-ZIFs (ZIF-8/ZIF-67) that was related to the accessibility of active centers to reagents and the strength of their interaction with CO2 and propylene oxide. The catalytic performance of Zn-ZIFs was found to improve with increasing the size of pore aperture due to the guest molecule facile diffusion and accessibility of the active site for reagent. In general, based on the results of the present work, the Zn-ZIFs could be considered as promising catalysts for cycloaddition of CO2 to epoxides and thereby opens new paths for further research.

Comparative study of continuous flow catalytic systems for the transformation of CO2 into propylene carbonate

This work presents a comparative study of two continuous flow reaction systems for the synthesis of propylene carbonate (PC) from CO2 and propylene oxide (PO). The reaction systems in continuous flow consist of a flow tubular reactor and a Robinson-Mahoney (RM) isothermal packed bed reactor in homogeneous regime. The formulation of the synthesized catalyst had KI as the active phase on a support of aluminum oxy-hydroxide, activated carbon, sodium dihydrogen sulfate, nitric acid and poly (vinyl alcohol); the mixture of materials was spheronized to improve its mechanical and workability properties. The results revealed that the reaction followed a catalyst deactivation pattern, since the yield under heterogeneous regime dropped for both reaction systems after the first 4 h of operation; however, the overall performance of the RM reactor, determined by Total Dynamic Performance (TDP) measurements, turned out to be 5 times higher than that of the tubular reactor. The RM reactor was then used in a mixed heterogeneous/homogeneous operation, thus keeping a sustained yield and selectivity of about 90 and 84%, respectively, for the total evaluation time (50 h) after adjusting to homogeneous regime. The mixed operation proposal using the RM reactor ensured the correct distribution of reagents and catalyst, along with the additional benefits of using a three-phase reactor system. In addition, the continuous flow operation allowed to maintain high performance and selectivity rates, enabling to continue the next stages of the scaling-up process.

Synthesis of Propylene Carbonate by Urea Alcoholysis—Recent Advances

Organic carbonates are considered the chemicals of the future. In particular, propylene carbonate is widely used as a non-reactive solvent, plasticizer, fuel additive, and reagent, especially in the production of environmentally friendly polymers that are not harmful to human health. This paper reviews recent literature findings regarding the development of propylene carbonate synthetic methods starting from propane-1,2-diol and urea. The ammonia formed during the synthesis is recycled to obtain urea from carbon dioxide.

Continuous flow synthesis of propylene carbonate using DBU-based ionic liquid in a packed bed reactor

Self-synthesis of green and high-efficiency DBU-based ionic liquid catalyst immobilized on SBA-15, conversion of CO2 into PC through the use of packed bed reactors. Tableting and changing the type of filler were adopted to tune the padding pattern of the catalyst in the reactor and improve the flow channel status. The effect of reaction temperature (45 ℃-90 ℃), operating pressure (1 MPa–4 MPa), CO2 flow rate (5 mL/min-100 mL/min), reaction time (2 h–8 h) on the yield of continuous flow synthesis of PC was investigated, and the catalyst activity also was evaluated by continuous use for 30 h. The intimate and direct contact of binary fluids leads to enhanced mass transfer and promoted reactions. Screen the optimal process conditions were 90 °C, 2 MPa, PO flow rate 0.1 mL/min, CO2 flow rate 5 mL/min, after continuous reaction for 2 h, the yield of PC could be achieved the highest, 57.10 %. Compared with the conventional batch reactor, the substrate was consumed immediately in the continuous reaction, and the product was generated in situ, and the reaction was safe and efficient, which provides guidance for industrial scale-up.

Quaternary ammonium salt functionalized MIL-101-NH2(Cr) as a bifunctional catalyst for the cycloaddition of CO2 with epoxides to produce cyclic carbonates

The reaction of CO2 with epoxides to produce cyclic carbonates requires high-performance, low-cost, and facilely recycled catalysts. Here, we report a heterogeneous catalyst (MIL-101-N(Bnme2)Br) based on metal-organic frameworks (MOFs) for catalytic CO2 conversion into cyclic carbonates. The MIL-101-N(Bnme2)Br catalyst was prepared as follows: A MOFs precursor (MIL-101-NH2) was firstly synthesized using a method of hydrothermal synthesis, then coupled with the quaternary ammonium salt ionic liquid (N(BzBnme2)Br) via aldehyde-amide condensation. A series of comparative experiments revealed that MIL-101-N(Bnme2)Br catalyst has high activity for catalyzing the cycloaddition reaction to produce cyclic carbonates in the absence of solvents and co-catalysts. As was exampled by the synthesis of propylene carbonate, a high yield (93 %) and selectivity (99 %) was achieved under the optimized conditions (0.93 mol% MIL-101-N(Bnme2)Br catalyst, 1.4 MPa CO2 pressure, 17 mmol propylene oxide, 100 °C, 5 h). More impressive, the MIL-101-N(Bnme2)Br catalyst could be recycled easily by filtration and was reusable up to several times without a significant activity decay. Furthermore, our density functional theory (DFT) calculations suggested that such high catalytic activity mainly resulted from the cooperative catalysis between the coordinatively unsaturated Cr3+ sites and Br anions in MIL-101-N(Bnme2)Br catalyst. Meanwhile, a possible mechanism for the cycloaddition reaction catalyzed by MIL-101-N(Bnme2)Br catalyst was also proposed.

Defective UiO-66-NH2 (Zr/Ce) catalyzes the synthesis of propylene carbonate under mild conditions

Abstract A series of UiO-66-NH2(Zr/Ce) catalysts were prepared by hydrothermal synthesis and studied its catalytic effect on the reaction of CO2 with propylene oxide. It was found that the addition of Ce ions can effectively reduce the number of UiO-66-NH2 connections. The BET results show that the specific surface area first increases and then decreases with the increase of Ce content. This is inconsistent with the changing trend of TGA, It is possible that the structure of UiO-66-NH2 is destroyed and the particles agglomerate. When the Ce/Zr molar ratio is 5%, UiO-66-NH2 (Zr/Ce) has the highest catalytic activity, because its larger specific surface area and pore volume are more conducive to catalytic reactions. Besides, the catalyst can remain stable after 4 catalytic cycles, but the activity is slightly reduced. It can be seen by in situ DRIFTS that the activated UiO-66-NH2 contains Lewis acid sites and Bronsted acid sites. Finally, we give two possible catalytic mechanisms.

Metal complexes bearing ONO ligands as highly active catalysts in carbon dioxide and epoxide coupling reactions

The use of carbon dioxide as feedstock in copolymerization reaction with epoxides has been ideally proposed as an alternative route to produce chemicals without the use of phosgene. One of the most appealing strategies is to use metal complexes as catalysts to form cyclic organic carbonates. These organic compounds are very interesting in industry due to their enormous scope of applications. In this paper, the use of catalytic systems based on sustainable, non-toxic and cheap metal complexes (Mn, Fe, Co) containing Schiff-base tridentate ONO ligands in the synthesis of propylene carbonate (PC) from carbon dioxide and propylene oxide (PO), are discussed. All complexes were tested successfully, affording cyclic carbonate in high productivities (3800 mol PC/mol cat) using a co-catalyst. Synthetized iron and manganese complexes have shown significantly higher activities compared with the activity showed by the new cobalt complexes. The catalytic conditions using the manganese (II) complex 2 were optimized and a TOF of 1600 h−1 was reached.

Kinetic study of highly efficient CO2 fixation into propylene carbonate using a continuous-flow reactor

Considered as an important C1 source on earth, carbon dioxide (CO2) utilization and fixation has aroused great attention. Synthesis of cyclic carbonate are one of the most widely industrialized routes. Ionic liquids have been studied for highly efficient cyclic carbonate production due to their distinguished characteristics. In this work, highly efficient synthesis of propylene carbonate catalyzed by [bmim]Br was achieved via a continuous-flow microreaction system. Based on that, influence factors and kinetics parameters for propylene carbonate synthesis were obtained. And the flow patterns were investigated via transparent tube, which were proved to be slug flow. The activation energy for [bmim]Br in this microreaction system was 57.4 kJ/mol with the temperature range from 110 to 140 ℃, and the reaction was found to follow first-order on PO and CO2 concentrations, and first-order on [bmim]Br concentration. Verification of the kinetic models was also studied and proved a less than 12 % error range.

Facile one-pot synthesis of ZnBr2 immobilized ion exchange resin for the coupling reaction of CO2 with propylene oxide

Abstract The synthesis of cyclic carbonate from CO2 and alkylene oxide is one of the best environment-friendly technologies for converting CO2 to valuable chemicals. In this study, a [ZnX2Cl2]2−immobilized ion exchange resin (ZnX2/IER) was synthesized using four kinds of zinc precursors, ZnX2 (X = Cl, Br, OAc, and NO3) and a chloride-anion exchange resin (IER). The synthesized ZnX2/IER was then used for the cycloaddition reaction of CO2 and propylene oxide (PO) to synthesize propylene carbonate (PC). Among the synthesized catalysts, ZnBr2/IER showed the highest activity, with a 76.7% PC yield achieved at 80 °C for 2 h, and 99.1% after 8 h. The catalytic activity was maintained during 5 times uses. The fresh and used ZnBr2/IER were characterized by FT-IR, SEM-EDS, and ICP-OES, and no noticeable changes in the morphology and zinc concentration were observed. The continuous reaction using a fixed-bed system for 96 h demonstrated that the synthesized catalyst can be employed in commercial PC synthesis processes.

Propylene carbonate synthesis from propylene oxide and CO2 over Ga-Silicate-1 catalyst

AbstractGallosilicate zeolite (Ga-Silicate-1) was synthesized and characterized by wet chemical analysis, Fourier transform infrared spectroscopy, X-ray diffraction, BET surface area analysis and 29Si MAS NMR. The prepared Ga-Silicate-1, calcined in the temperature range from 350°C to 550°C, was tested as a catalyst for the synthesis of propylene carbonate (PC) from CO2 and propylene oxide in a solvent-free reaction. The effects of various parameters, such as co-catalyst, reaction temperature, reaction time, and pressure of CO2, on the reaction were investigated. It has been found that increasing the calcination temperature from 500°C to 550°C decreased both the conversion and selectivity to PC from 63.7% to 20.6% and from 77.6% to 58.9%, respectively. Unlike conversion and selectivity, the surface area increased from 96.1 to 103.8 m2/g. This significant increase in surface area due to the degalliation of the zeolite, along with the decrease in conversion, clearly indicates the role of gallium in the production of PC. Under mild reaction conditions (75°C and P(CO2) = 0.55 MPa), a conversion of 70.8% and a selectivity of 81.3% were obtained. Based on the obtained results, a mechanism for the synthesis of PC over the Ga-Silicate-1 catalyst was proposed.