Atm Pressure Research Articles

Theoretical Insights into the Gas-Phase Oxidation of 3-Methyl-2-butene-1-thiol by the OH Radical: Thermochemical and Kinetic Analysis.

3-Methyl-2-butene-1-thiol ((CH3)2C═CH-CH2-SH; MBT) is a recently identified volatile organosulfur compound emitted from Cannabis sativa and is purported to contribute to its skunky odor. To understand its environmental fate, hydroxyl radical (•OH)-mediated oxidation of MBT was conducted using high-level quantum chemical and theoretical kinetic calculations. Three stable conformers were identified for the title molecule. Abstraction and addition pathways are possible for the MBT + OH radical reaction, and thus, potential energy surfaces involving H-abstraction and •OH addition were computed at the CCSD(T)/aug-cc-pV(T+d)Z//M06-2X/aug-cc-pV(T+d)Z level of theory. The barrier height for the addition of the OH radical to a C atom of the alkene moiety, leading to the formation of a C-centered MBT-OH radical, was computed to be -4.1 kcal mol-1 below the energy of the starting MBT + OH radical-separated reactants. This reaction was found to be dominant compared to other site-specific H-abstraction and addition paths. The kinetics of all the site-specific abstraction and addition reactions associated with the most stable MBT + OH radical reaction were assessed using the MESMER kinetic code between 200 and 320 K. Further, we considered the contributions from two other conformers of MBT to the overall reaction of MBT + OH radical. The estimated global rate coefficient for the oxidation of MBT with respect to its reactions with the OH radical was found to be 6.1 × 10-11 cm3 molecule-1 s-1 at 298 K and 1 atm pressure. The thermodynamic parameters and atmospheric implications of the MBT + OH reaction are discussed.

Modification of cellulose acetate membrane by integrating magnetite@xanthan gum nanocomposite to enhance performance characteristics

Membrane technology, a versatile alternative to traditional separation processes in industries and wastewater treatment, was employed in this study. Membranes were fabricated using cellulose acetate (C), dimethyl sulfoxide (D), and glycerol (G) at various weight percentages. To enhance membrane performance, a Magnetite@Xanthan gum nanocomposite (NC) was synthesized in-situ and analysed using FESEM-EDS. Experimental investigations incorporated the doping of the membrane with NC at different percentages (0 wt%, 0.1 wt%, 0.5 wt%, and 1.0 wt%). Increasing NC content resulted in smoother surfaces, improving anti-fouling characteristics, as confirmed by AFM. Integrating NC into the pure membrane reduced the contact angle, with 1.0 wt% Fe3O4@XG recording the lowest angle at 56.18°. Physical property analyses covered viscosity, pH, water uptake percentage, and porosity to assess the impact of NC integration. Under 5 atm pressure, the 1.0 wt% Fe3O4@XG membrane exhibited a substantial pure water flux of 3069.55 lit.m-2 h−1 compared to pure CDG. Furthermore, the 0.5 wt% Fe3O4@XG membrane displayed the highest flux recovery ratio (60.42%) compared to pure CDG (48.18%). A biodegradability test showed that the 1.0 wt% Fe3O4@XG membrane exhibited superior weight loss (43.75%) over 28 days. This research underscores the potential of these membranes for diverse applications, including wastewater treatment and sustainability.

Study of stress corrosion cracking susceptibility of irradiated ferrite-martensitic stainless steel 07Kh12NMFB in supercritical water. Part 2. Development of corrosion crack identification technique and analysis of autoclave test results

The studies of stress corrosion cracking have been carried out for the stainless ferritic-martensitic steel with chromium content of 12% irradiated to a damage neutron dose of ~12 dpa. This steel was chosen as a candidate material for the internals of supercritical water-cooled reactors (SWCR).The first part of the paper was devoted to autoclave testing of specially designed disk specimens under constant load in a supercritical water environment (at 450°C and 250 atm pressure). In this part of the article the developed technique for corrosion cracks identification is presented and analysis of autoclave tests results is performed.As a result of the experiments performed, the threshold stress values below which stress corrosion cracking initiation doesn’t occur. The values of threshold stresses are determined for the studied steel irradiated at temperatures of 390 and 550°C. Possible mechanisms of stress corrosion cracking of the studied steel are analyzed and directions for further research are proposed.

High performance hydrogen evolution energy conversion devices via p type polaron surface state modulation

The processing of solar to hydrogen energy conversion semiconductor devices strongly relies on the charge mobility and reactivity of hydrogen evolution reactions. Intrinsic defects induced polaron has been applied on the surface of Cu2O polyhedron nanoparticles to modulate the hydrogen cations reduction and hydrogen evolution reaction by high charge mobility and H atoms high selective of specific external terminated atoms. With the polaron surface state applied on truncated octahedron Cu2O nanoparticle photocathode, the water splitting efficiency achieved 2.12 % at 0.2 V working bias. The hydrogen generation rate is as high as 9.38 L/m2⋅h. Besides, under 1.23 V applied bias, at 1 atm pressure and room temperature, there are over 64 L hydrogen gases are generated in only one hour, and the hydrogen generation rate is as high as 65.39 L/m2⋅h. During this study, a defined p typed polaron surface state for raising charge mobility and hydrogen evolution in solar to hydrogen conversion system is illustrated, which provides the reliable application in related photon to electron conversion and high performance energy conversion devices.

Protic- or anionic-NHCs with a classical-NHC in a single [Ru(CNC)(PPh3)2Cl]Cl pincer complex: direct comparison of structure & electronic properties and heterolytic H2 splitting.

Herein, we report the first set of pincer complexes 1 and 2 with the general formula [Ru(CNC)(PPh3)2Cl]Cl having a protic- and classical-NHC in the same molecule and nearly identical environments. Deprotonation of the protic-NHC complex 2 with one equivalent of base leads to the formation of anionic-NHC complex 2'. These complexes allow a direct comparison of protic- and anionic-NHCs with the classical-NHC ligand. A comparison of the molecular structure indicated that the metal carbene bond length trend is anionic-NHC > protic-NHC > classical-NHC. The electrochemical investigation revealed the electron donation tendency is classical-NHC > protic-NHC and anionic-NHC > protic-NHC. Cooperation between the metal and the ligand is indicated by the reaction of 2' with H2 gas at 1 atm pressure and 110 °C to give the Ru-hydride complex 3.

Nonlinear Scattering of 248 nm Wavelength Light in High-Pressure SF6 and CH4 Gases for the Temporal Compression of a 20 ns KrF Laser Pulse

The nonlinear compression of narrowband (Δν ≈ 0.2 cm−1) 20 ns KrF laser pulses in SF6 at 10 atm and in CH4 at 50 atm pressure was studied. Both SBS and SRS optically phase-conjugated backward-reflected radiation was registered with an energy reflectivity of 10–14% in SF6 and CH4. In SF6, the SBS pulses gradually shortened from 10 ns to 2–3 ns with a decrease in pumping to the SBS threshold of ~10 mJ, while the SRS pulse had the shortest length of 30–60 ps for the maximal pumping of 120 mJ and broadened near the SRS threshold of ~30 mJ. For the SRS pulse energy, the ~2 mJ peak power 5 × 107 W was tenfold higher than the pump power. The theoretical model predicted a soliton-like SRS pulse compression to a temporal length of the order of the vibrational relaxation time. There was no pulse compression of backward SBS and SRS radiation in CH4, while, in the forward direction, SRS pulses shortened to 3–4 ns at reduced pumping.

Extraction Study of Lignite Coalbed Methane as a Potential Supplement to Natural Gas for Enhancing Energy Security of Western Macedonia Region in Greece

Greek lignite reserves are mainly located in the northwestern part of the country (Region of Western Macedonia, Greece), reaching a total of 5 billion tons. Considering that Greece is planning to stop burning lignite for electricity production, the recovery of the CH4 trapped in lignite coalbed reservoirs can be a valuable alternative for power generation and may help to reduce the direct emissions of methane during mining activities. The aim of the present study was to evaluate the LCBM in the Region of Western Macedonia, Greece (Ptolemaida basin). In order to assess the LCBM that could be extracted, three samples were collected from an active mine and were subjected to desorption experiments at different temperatures (25 °C, 50 °C, 100 °C, and 150 °C) by channeling high purity Ar gas at 1 atm of pressure. According to the results, the highest amount of CH4 was extracted during the desorption process at 50 °C, while the total amount of CH4 from all three samples was 0.82 m3/kg, confirming the presence of CH4 in the lignite deposits. Finally, a SWOT analysis was carried out that shows the strengths and opportunities against the weaknesses and threats of a potential LCBM exploitation in Greece, while also taking into account the social, economic, and environmental nexus.

A DFT investigation of Osmium decorated single walled carbon nanotubes for hydrogen storage

The investigation for hydrogen storage in armchair single walled carbon nanotubes (SWCNTs) with decoration of osmium atom on the surface of tube has been done using ab-initio method utilizing Density Functional Theory (DFT). In the present work, single/dual osmium atoms decoration on the surface of SWCNTs (5,5) has been investigated regarding the effects on structural, electronic and thermodynamic properties. Frontier molecular orbital (FMO) i.e. HOMO and LUMO structures and electrostatic potential surfaces (ESP) of all geometrically optimized and stable species are studied. Investigations regarding metal-metal clustering are carried out by calculating diffusion barrier energy for osmium atoms and atomistic molecular dynamic simulations performed at 300°K temperature for 1ps. It is found that osmium decoration on SWCNTs enhances the hydrogen storage capacity via spillover mechanism. It is observed that the adsorption energy per hydrogen molecule in case of Pristine SWCNT is -0.001eV, which is increased with decoration of osmium atoms and finally found to be -0.575eV/H2 in case of single osmium decorated SWCNT (Os-CNT) and -0.681eV/H2 due to double osmium decoration on SWCNT (2Os-CNT). This study reveals gravimetric hydrogen storage capacity of 1.32 wt% and 2.53 wt% for Os-CNT and 2Os-CNT respectively at 298.15 K temperature and 10 atm pressure. Average Van't Hoff desorption temperature for osmium decorated SWCNTs are also calculated.

First principle studies on triphenylene-hexathiol-based metal-organic framework for hydrogen storage application

We have studied the hydrogen storage capability of the recently synthesized triphenylene-hexathiol based metal-organic framework (MOF) with Fe and Cu metal atoms by using density functional theory and Ab Initio Molecular Dynamics (AIMD) simulations. We found that up to 12 hydrogen molecules were spontaneously adsorbed on the six Fe atoms of the MOF (FeMOF) with adsorption energy of −0.18 eV per H2 molecule, whereas only six H2 molecules were adsorbed on the six Cu atoms of the MOF (CuMOF) with an adsorption energy of −0.17 eV per H2 molecule. Hydrogen molecules were adsorbed on the Fe atom in the FeMOF surface by Kubas interaction. It is observed that the H2 storage capacity of FeMOF did not change due to the substitution of electron donating group, OCH3 on triphenylene molecules. The charge transfer from H2 molecules to the MOF through metal atoms has been confirmed through the density of states and Bader charge analysis. The gravimetric weight percentage of the FeMOF is found to be 1 wt% at room temperature and 1 atm pressure which is considerably higher than that of the studied CuMOF (0.5 wt%). Further, the AIMD results confirmed the structural stability of the studied MOFs. Therefore, the studied FeMOF surface is a suitable material for efficient and reversible hydrogen storage application.

EFFECTS OF HYPERBARIC OXYGEN THERAPY ON INTESTINAL ISCHEMIA-REPERFUSION AND ITS MECHANISM.

Ischemia can cause reversible or irreversible cell or tissue damage, and reperfusion after ischemia not only has no therapeutic effect but also aggravates cell damage. Notably, gut tissue is highly susceptible to ischemia-reperfusion (IR) injury under many adverse health conditions. Intestinal IR (IIR) is an important pathophysiological process in critical clinical diseases. Therefore, it is necessary to identify better therapeutic methods for relieving intestinal ischemia and hypoxia. Hyperbaric oxygenation refers to the intermittent inhalation of 100% oxygen in an environment greater than 1 atm pressure, which can better increase the oxygen level in the tissue and change the inflammatory pathway. Currently, it can have a positive effect on hypoxia and ischemic diseases. Related studies have suggested that hyperbaric oxygen can significantly reduce ischemia-hypoxic injury to the brain, spinal cord, kidney, and myocardium. This article reviews the pathogenesis of IR and the current treatment measures, and further points out that hyperbaric oxygen has a better effect in IR. We found that not only improved hypoxia but also regulated IR induced injury in a certain way. From the perspective of clinical application, these changes and the application of hyperbaric oxygen therapy have important implications for treatment, especially IIR.

Pristine [formula omitted] monolayer as highly efficient reversible hydrogen storage material under ambient temperature and pressure

The advent of 2D materials has made physisorption-based H2 storage a promising alternative to conventional techniques involving high pressure and cryogenic temperature. However, most of the reported 2D materials require the addition of metal atoms or the application of an electric field to meet the U.S. Department of Energy (DoE) target of 6.5% gravimetric storage capacity for practical usage. Based on density functional theory (DFT), we show 2D BC6N, in its pristine form, demonstrates a storage capacity of 11.11 wt% with a binding energy of 0.139 eV per H2. At 1 atm pressure, the desorption occurs at temperatures above 118.23 °C, making the storage fully reversible at experimentally conceivable temperatures. The study of the desorption temperatures at varied external pressures indicates a broad operational range for commercial usage. Such high uptake capacity at ambient conditions makes pristine 2D BC6N an ideal candidate for metal-free, reversible hydrogen storage.

Investigation of the decomposition mechanism of MTNP melt-cast explosive at different temperatures and pressures through ReaxFF/lg molecular dynamics simulations.

Thermal decomposition of 1-methyl-3,4,5-trinitropyrazole (MTNP), a melt-cast explosive, was investigated at different temperatures (2500, 2750, 3000, 3250, and 3500 K) and pressures (3000 K/0.5 GPa, 3000 K/1 GPa) using the ReaxFF/lg force field. The study aimed to analyze the changes in reactant quantities, initial reaction pathways, and final product yields. The results demonstrated that complete decomposition of MTNP molecules occurred within a timeframe of 200 ps, with shorter decomposition times observed as the temperature increased. The high-temperature thermal decomposition of MTNP was found to follow two primary reaction pathways. Reaction 1 involved denitration, while reaction 2 proceeded with nitro group isomerization. DFT calculations indicated that nitro group isomerization was the most favorable reaction. During the initial stages, higher quantities of NO2, NO, and N2 were observed compared to other species. This can be attributed to the relatively higher nitrogen and oxygen content in the MTNP structure. Among the five reaction temperatures, it was observed that the quantities of small molecules followed the order of NO2 > NO > N2 > CO. Moreover, with increasing temperature, the quantities of all four small molecules increased, indicating that higher temperatures promoted the progression of the reactions. However, as the pressure increased, there was a trend of initially increasing and then decreasing to zero for the quantities of NO2 and NO. This suggests that high temperature accelerated the high-temperature thermal decomposition of NO2 and NO, leading to a significant increase in the content of N2. A 3 × 5 × 5 supercell model of MTNP was constructed in Materials Studio, consisting of 75 unit cells and 300 MTNP molecules. The model was then subjected to a 20 ps geometric optimization using the Polak-Ribiere version of the conjugate gradient (CG) algorithm in the large-scale atomic/molecular massively parallel simulator (LAMMPS) under the isothermal-isobaric (NPT) ensemble at 1 atm pressure and 300 K temperature. Following the optimization, molecular dynamics simulations were performed on the model at five temperatures (2500, 2750, 3000, 3200, and 3500 K) under 1 atm using the NPT ensemble for a total duration of 1 ns. During the simulations, atomic trajectories, as well as information on atomic and molecular species, were output every 500 steps. Subsequently, a custom script was utilized to analyze the thermal decomposition pathways and products. A time step of 0.1 fs was employed for the calculations, and periodic boundary conditions were applied to eliminate boundary effects.

Effect of cross-flow velocity on spray evolution and impingement characteristics of a multi-hole port fuel injector

The location and orientation of the injector play a crucial role in determining engine performance and emissions from spark ignition and dual-fuel compression ignition engines. This study focuses on the spray atomization and downstream mixing of gasoline injected from a multi-hole port fuel injector in a crossflow. This study employed the phase Doppler interferometry technique to extract the droplet size and velocity distributions for the flow confined in a circular duct with a diameter similar to the intake port of the dual-fuel compression ignition engine. The flow velocity was maintained at 10 m/s at 1 atm pressure and 299 K temperature. The spray characteristics were compared for the quiescent and crossflow cases. The spray evolution was analyzed using a high-speed imaging technique. Near wall impingement analysis has been carried out using the spray impingement models. The early stage spray evolution was similar for the quiescent and crossflow cases. The horizontal velocity of the spray was found to be ∼12 m/s at 20 mm downstream of the injector. The velocity remained similar for the flow and no-flow cases, as drag force was found to have an insignificant effect. The drag force was estimated to be one order of magnitude higher for the 15-μm droplet than the 50-μm droplet. The maximum Sauter mean diameter observed for the flow case inside the spray was 53 μm, which was 18% higher than the maximum Sauter mean diameter of the no-flow case. The droplet Sauter mean diameter increased along the spray due to the coalescence of slow-moving droplets. The droplet breakup was found to be insignificant downstream of the spray. The flow entrained the droplets smaller than 30 μm. The spray-wall impingement criterion estimated around 42% of droplets to bounce off the surface at 50 mm, compared to 22% without flow.

Vacuum freeze dryer technology for extending the shelf life of food and protecting the environment: a scenario study of the energy efficiency.

This study focused into vacuum freeze dryer technology for increasing food shelf life in a drying food technology. The determinants of energy consumption increase as the energy density of food production and storage increases. Reducing the amount of energy used for drying, freezing, chilling, refrigeration, and air conditioning is becoming more important. The objective of this study was to extend food's shelf life utilizing creative and novel technical approaches, such as vacuum freeze-drying's energy-efficient process. Despite being a part of this investigation, the vacuum freeze drier was created using environmentally benign energy sources. To minimize the carbon footprint of food preservation, it is essential to use eco-friendly energy sources in chilling storage. According to the first law of thermodynamics, the energy efficiency at 1 atm pressure and 25 [°C] temperature (neglecting potential and kinetic energies) in the dead state is calculated under thermal equilibrium conditions. In this study, the energy efficiency was shown according to 5 different scenarios. The results of energy efficiencies are as follows: η1 is from 14.3 to 21.4%, η2 is from 20.7 to 31.0%, η3 is from 27.3 to 40.9%, η4 is from 32.1 to 48.1%, and η5 is from 34.6 to 51.9%, respectively. This analysis demonstrates that the energy efficiency improved from 12 to 18 h. In this study, optimizations with scenarios were employed considering vacuum freeze-drying technology in the plant with sustainable energy sources can considerably improve food shelf life while limiting our environmental impact.

Carboxylative cyclization of propargyl alcohols with carbon dioxide for the synthesis of α-alkylidene cyclic carbonates in presence of Co(III) schiff base complex catalyst

A cobalt(III) complex, [Co(L)3](DMF) (1) of Schiff base ligand HL, 2-((E)-(benzylimino)methyl)-4-bromophenol is prepared and single crystal X-ray structural analysis have also been performed. The structures of complex 1 showed hexa-coordinated mononuclear systems that adopt octahedral geometry. The complex has also exhibited the supramolecular networks through non-covalent interactions like H-bonding, C–Hπ stacking. Moreover, the complex 1 is very effective in the catalytic fixation of carbon dioxide in propergyl alcohols to produce α-alkylidene cyclic carbonates. The catalytic production of α-alkylidene cyclic carbonates have been carried out through carboxylative cyclization of propargyl alcohols using CO2 balloon of 1 atm pressure at 80 °C. Solvent free condition (green synthesis) made this catalytic protocol eco-friendly towards the environment. Utilizing various substrates of propargyl alcohols moderate to high percentage yield (62–95%) of respective α-alkylidene cyclic carbonates product have been isolated over this catalytic reaction. Besides, the theoretical calculations (DFT) was performed for the prediction of probable mechanism of the catalytic reaction.

Double-Walled Covalent Organic Frameworks with High Stability.

Double-walled covalent organic frameworks, consisting of two same building blocks parallel to each other forming ladder-shape linkers, could enhance the stability of the frameworks and increase the density of functional sites, thus making them suitable for various applications. In this study, two double-walled covalent organic frameworks, namely DW-COF-1 and DW-COF-2, were successfully synthesized via imine condensation. The resulting DW-COFs exhibited a honeycomb topology, high crystallinity and stability. Particularly, DW-COF-2 showed excellent resistance toward boiling water, strong acid, and strong base, due to its double-wall structure, which limits the exposure of labile imine bonds to external chemical environments. The DW-COFs showed high porosity near 900 m2/g, making them suitable for gas storage/separation. The selective gas adsorption experiments showed that at 273 K and 1 atm pressure, DW-COF-1 and DW-COF-2 exhibited a good IAST selectivity towards CO2/N2 (15/85) adsorption, with selectivity values of 121.3 and 56.4 for CO2 over N2, respectively.

Development of Essential Oil Potential as Raw Material for Making Mi Amore Perfume in Jeulekat Village, Blang Mangat District

Along with the development of modern industries such as the perfume, cosmetic, food, aromatherapy and pharmaceutical industries, the world's need for essential oils is increasing every year. Several parameters developed in this article include the effect of pressure (1, 2, 4, 6, 8) mmHg and time (20, 40, 60) minutes until final boiling point on the volume of oil produced and geraniol concentration. The analysis carried out was GCMS analysis and bacterial activity in the application of perfume products. From the research results it was found that at 1 atm pressure the geraniol concentration increased by 50% to 80.11%. Apart from these compounds, other compounds were also obtained such as citronellol, rhodinol and cheprol. at this pressure also produced the highest product volume of 21.2 ml. The application of the product resulting from the vacuum distillation process in the form of an anti-bacterial perfume at an incubation time of 48 hours has the strongest anti-bacterial activity with a diameter of 10.13 mm against Staphylococcus aureus bacteria.

Thermo-Calc determination of phase diagram and thermodynamic properties of Ni-Al binary system

Ni-Al alloys have good corrosion-resistant properties making them preferable as a material of choice compared to ordinary metals. A good understanding of the phase diagram and thermodynamic properties of the Ni-Al alloy binary system is essential in determining relevant industrial applications of the system. The Ni-Al phase diagram is being reassessed since those found in the literature are based on old experimental studies. The phase diagram and thermodynamic properties of the Ni-Al alloy is determined using the Thermo-Calc 2022b software over a temperature range of 200 K to 2000 K and 1 atm of pressure. A total of nineteen fields (including elemental Al and Ni) comprising five single solid phases, one liquid phase, and twelve double regions were obtained from the equilibrium calculation. The thermodynamic calculation has six invariant reactions containing two eutectic reactions (914.83 ± 0.025 K and 1641.80 ± 0.025 K), three peritectic reactions (1123.55 ± 0.025 K, 1400.72 ± 0.025 K and 1642.65 ± 0.025 K), and one peritectoid reaction (913.96 ± 0.025 K). The solubility of Al in Ni is also determined. The Gibbs free energy, the molar enthalpy and the activities of Al in Ni are all calculated at temperatures 913 K, 1642 K, and 1953 K. The Thermo-Calc temperature – composition of the Ni-Al alloy is compared with the existing experimental studies to identify the physical properties of the different thermodynamic properties of the Ni-Al alloy binary system.

Simulation And Optimization Of Hydrogen Production By Steam Reforming Of Natural Gas

Hydrogen (H2) production through natural gas steam reforming is widely adopted due to its cost-effectiveness and energy efficiency. A simulation and optimization study was performed on an industrial natural gas steam reforming system using Aspen Hysys V12 software to optimize this process. The study focused on optimizing various parameters, including the Reformer Reactor, Water Gas Shift Reactor, and purification units such as the Separator and Pressure Swing Adsorption (PSA). The Reformer and Water Gas Shift reactors were set at 900 °C and 300 °C, respectively, to maximize hydrogen production. Under specific conditions of 5 atm pressure and a steam-to-carbon ratio (S/C) of 2.5, the process achieved a hydrogen production rate of 402.2 kg/h. The treatment zone effectively eliminated ~ 100% of undesirable CO2 and CO gases, with only trace amounts of CH4 and H2 remaining in the waste gases. Additionally, the PSA unit efficiently removed ~ 100% of the water from the separator, ensuring water-free dry gases were sent to the PSA unit. The integration of heating and cooling heat exchange units reduced energy consumption by approximately 51.6%. After the removal of undesired gases in our PSA unit, the production yield for the final product (H2, based on dry gas inlet to PSA) is 77.83%, resulting in 100% pure dry H2. In the waste gas outlet (tail gas) of PSA a composition (22.17%), includes CO, CO, H2O, and CH4. Resulting high-quality hydrogen is well-suited for a wide range of applications, including fuel cells, petroleum refining, natural gas refineries, and petrochemical processes.

Two novel types of heterogeneous catalysts apply to synthesize cyclic carbonates through CO2 fixation on epoxides under mild condition

The present work focuses on developing heterogeneous catalysts for conversion of CO2 and mono-/di-epoxides to mono-/bis-cyclic carbonates. To achieve this purpose, two types of recyclable solid catalysts, namely polyurethane (PU-BTP) and polyurethane modified on silica gel-solid support (SG-AU-BPT), are synthesized. On these catalysts, the key promoter CaI2 is pre-absorbed. Both catalysts show high catalytic activity under mild conditions. For example, phenyl glycidyl ether (PGE) can be converted to 4-(phenoxymethyl)− 1,3-dioxolan-2-one at 60 °C within 6 h under 1 atm pressure of CO2. PU-BTP and SG-AU-BPT can be recollected by suction filtration and reused for eight times with conversion larger than 81% and 95% respectively. These results indicate that the degree of CaI2 leaching out from the catalysts in each cycle and loss is low.