Papers by Keyword: Propylene Oxide

Abstract: Ionic liquid with a single hydroxyl group, 1-(2-hydroxyl-ethyl)-3-methylimidazolium bromide (HEMIMB), was prepared. It was found that HEMIMB could be an efficient catalyst for CO2 cycloaddition to propylene oxide to produce propylene carbonate (PC). An ionic liquid polymer with multi-hydroxyl groups poly(1-2-hydroxyl-ethyl)-3-vinylimidazolium bromide (PHEVIMB) was also prepared. In this study, both catalytic reaction performances of HEMIMB and PHEVIMB were investigated. Results showed that product separation and catalyst recycles in the process of PHEVIMB catalytic reaction system was much more efficient with a yield of 55.5%, even after three consecutive catalyst reuses. Meanwhile, the separation was less time-efficient for homogeneous catalytic system of HEMIMB molecules with a single hydroxyl group despite of a yield of 92.4%. When it comes to practical industrial process design, the single component with multifunctional ionic liquid polymer, as catalyst, may be considered effective and friendly process.

Abstract: In this investigation, nanoSchiff bases Cobaltic complex was synthesized and used as the initiator in the copolymerization of carbon oxide and propylene oxide (PO). The nanoCobaltic complex was characterized by infrared spectroscopy (IR), and nuclear magnetic resonance spectroscopy (NMR). The influences of different factors, including reaction time, reaction temperature, and pressure of CO₂ on the synthesis of polycarbonate were described. The results show that nanoCobaltic complex could be successfully applied in the copolymerization of CO₂ and PO. The optimum conditions of the polymerization, which include CO₂ pressure of 30 bar, reaction temperature of 80 °C, and reaction time of 3 hours.

Abstract: In the one compartment electrochemical cell equipped with platinum electrodes electrochemical fixation carbon dioxide was conducted under ambient conditions. Ionic liquid BMimBr is supporting electrolyte. The aimed product dimethyl carbonate was electrosynthesized in a dialkylimidazolium ionic liquids-propylene oxide-methanol system under normal temperature and pressure. The result indicated that the highest yield of 37.8 % was obtained in the condition of working temperature 30 °C, electrolytic voltage 5.5 V, the mass of CH₃OH 0.484 mol, propylene oxide 0.052 mol and bmimBr 0.059 mol.

Abstract: In this paper, propylene oxide has been first used to modify octylpolyglycol phenylene phosphite (OPGPP). A novel thermoregulated ligand OPGPP-Rh was synthesized for enlarging the application range of thermoregulated phase separable catalysis (TPSC) proposed by us. The ligands being studied have distinct critical solution temperature (CST) in some organic solvents. The CST of OPGPP (EO+PO=26+6) is 70°C in heptane. The authors further investigated the catalytic activity, separation and recycling efficiency of rhodium complex for hydroformylation of 1-octene in the catalytic system with CST. The optimal reaction conditions were as follows: T=100 °C, p=6.0MPa, CO:H₂=1:1, reaction time of 5 hours, n (substrate to Rh)=1000, the solvent of heptane. Under the above conditions, the conversion of 1-octene and yield reached 90% and 88%, respectively. The catalyst could be recycled for five times without obvious loss in catalytic activity.

Abstract: The adsorption of propylene oxide (PO) onto MgO, ZnO and Al₂O₃ was investigated by using in situ-IR measurements. Detailed mechanisms for PO adsorption onto these metal oxides are proposed. It was found that the PO epoxide ring exhibits two opening tendencies, depending on the acid-base properties of the metal oxide. PO adsorbed onto MgO is preferentially opened at the O-C (1) bond. The epoxide ring provides two ways to open, at the O-C (1) or the O-C(2) bond on Al₂O₃. PO adsorbed onto ZnO showed no chemical adsorption on its surface.

Abstract: Three salen complexes N,N'-bis(salicylidene)-1,2-phenylenediamino MⅢ Cl were prepared and employed for the copolymerization of carbon dioxide with propylene oxide. FT-IR and UV-Vis spectra confirmed the characteristic of metal salen complexes obtained. The central metal atoms in the salen complexes have great influence on the copolymerization of carbon dioxide with propylene oxide. The result shows that chromium metal is more effective to synthesize PPC copolymer. The structure of the resulting PPC was characterized by IR 1H NMR and GPC. 86.3% carbonate content of the PPC was achieved with chromium salen complexes.

Abstract: Zirconium diboride nano-powders were synthesized by novel sol-gel technology using zirconium oxychloride, boric acid and sucrose as row materials. Different sol network modifiers, such as propylene oxide (PO) and citric acid (CA), were used to control the formation of zirconia precursor sol, respectively. PO could stabilize the sol by protonation and ring-opening reactions, and CA could form the sol network by chelation, then transformed to gel network. Gel was dried, ground, and exposed to carbonthermal reduction heat treatment (1500°C, 2h, flowing 95%argon mix with 5% hydrogen) to prepare ZrB2 nano-powders. In this study, effects of sol network modifiers on preparation procedure, powder characteristics were performed by using Infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Transmission electron microscopy (TEM). The purity of ZrB2 will improve by increasing the molar ratio of B/Zr, the photomicrograph revealed nearly pure ZrB2 nano-powders with spherical shape of 50-200nm and well dispersed were obtained with a molar ratio of B/Zr of 3.0 at 1500°C for 2h using PO as chemical modifier.

Abstract: A novel and green mechanochemical technique, the grinding-based method, was applied for synthesis of multi-metal cyanide (MMC) complexes. In order to discovery the effect of metal element on structure and catalyst efficiency, the obtained three MMCs were made from deferent three metal salts groups, which including ZnCl2 to NiCl2 to K3Fe(CN)6 molar ratio of 4:3:1 (MMC-1), ZnCl2 to NiCl2 to K3Co(CN)6 molar ratio of 4:4:1 (MMC-2), and ZnCl2 to NiCl2 to K4Fe(CN)6, respectively. And three MMCs were further used for copolymerization of CO2 and propylene oxide. FTIR and 1H NMR results shown, the alternating copolymerization obtained anticipated poly(propylene carbonate) with high catalytic activity. Comparing to the conventional solvent-based synthesis, the strikingly efficient and practically applicable grinding-based method reveals clear merits for syntheses of MMC complexes.

Abstract: An ionic liquid 1- (triethoxysilyl) propyl-3-methylimidazolium hydroxide ([Smim]OH) was grafted on three kinds of mesoporous hydrophobic silica gel by means of post-grafting under mild conditions. The catalysts were [Smim]OH/SiO2-MTES (methyltriethoxysilane), [Smim]OH/SiO2-TMCS (trimethylchlorosilane), [Smim]OH/SiO2-CPTEO (triethoxysilyl propyl chloride). Such grafted ionic liquids (GILs), which were characterized by means of FTIR and N2 adsorption-desorption could be used as effective heterogeneous catalysts toward propylene carbonate synthesis through cycloaddition of carbon dioxide with propylene oxide under solventless and mild conditions.

Abstract: Ethylene oxide (EO) and propylene oxide (PO) random copolymer was synthesized with 1,2-propanediol as initiator, then the end-capping process was carried out by adding various alkyl halides and potassium hydroxide (KOH) to produce the double alkyl EO/PO random copolyethers. The factors effecting alkyl-capping rate were discussed. The results showed that when the molar ratio of hydroxyl group/KOH/1-bromobutane was 1/1.9/1.9, reacting time 6.5 hr and reacting temperature 50°C, the alkyl-capping rate could reach over 80%. The end-capping rate would also increase with the increasing content of ethylene oxide in the random polyether, and the end-capping rate of the EO/PO/EO block-polyether was high than that of the random polyether with same molecular weight. Instead of 1-bromobutane, ethyl bromide promised a higher whereas chloralkane gave a lower end-capping rate respectively.