Phase equilibria of the propylene glycol/CO2 and propylene glycol/ethanol/CO2 systems

The high-pressure vapour–liquid phase equilibria (P–T–x–y) of the binary mixture propylene glycol/CO₂ have been experimentally investigated at temperatures of (398.2, 423.2 and 453.2) K over the pressure range from (2.5 to 55.0) MPa using a static-analytic method. Furthermore, the high-pressure vapour–liquid phase equilibria (P–T–x–y) of the ternary mixture propylene glycol/CO₂/ethanol at constant temperatures of (398.2, 423.2 and 453.2) K and at constant pressure of 15.0 MPa have been determined using a static-analytic method. Initial concentrations of components in propylene glycol (PG)/ethanol (EtOH) mixture vary from 10 up to 90 wt.%. In general, for binary system it was observed that the solubility of CO₂ in the heavy propylene glycol reach phase increases with increasing pressure at constant temperature. On the contrary, the composition of gaseous phase is not influenced by the pressure or the temperature. On average the solubility of PG in light phase of CO₂ amounts to 30 wt.%. The system behaviour at temperature of 398.2 K was investigated up to 70.0 MPa and a single-phase region was not observed. Above the pressure 60.0 MPa a single-phase region of the system was observed for the temperature of 423.2 K. For the temperature of 453.2 K the single-phase was observed above the pressure of 48.0 MPa. For ternary system it was observed that the composition of heavy phase is slightly influenced by the temperature when the mass fraction of EtOH in initial mixture is higher than 50 wt.%. If the mass fraction of PG in initial mixture is higher than 50 wt.%, the composition of heavy phase is not influenced by the temperature anymore. The composition of the PG, EtOH and CO₂ in light phase remains more or less unchanged and it is not influenced by the conditions.     

Selective hydrogenolysis of glycerol to propylene glycol on Cu–ZnO catalysts

Hydrogenolysis of biomass-derived glycerol is an alternative route to sustainable production of propylene glycol. Cu–ZnO catalysts were prepared by coprecipitation with a range of Cu/Zn atomic ratio (0.6–2.0) and examined in glycerol hydrogenolysis to propylene glycol at 453–513 K and 4.2 MPa H₂. These catalysts possess acid and hydrogenation sites required for bifunctional glycerol reaction pathways, most likely involving glycerol dehydration to acetol and glycidol intermediates on acidic ZnO surfaces, and their subsequent hydrogenation on Cu surfaces. Glycerol hydrogenolysis conversions and selectivities depend on Cu and ZnO particle sizes. Smaller ZnO and Cu domains led to higher conversions and propylene glycol selectivities, respectively. A high propylene glycol selectivity (83.6%), with a 94.3% combined selectivity to propylene glycol and ethylene glycol (also a valuable product) was achieved at 22.5% glycerol conversion at 473 K on Cu–ZnO (Cu/Zn = 1.0) with relatively small Cu particles. Reaction temperature effects showed that optimal temperatures (e.g. 493 K) are required for high propylene glycol selectivities, probably as a result of optimized adsorption and transformation of the reaction intermediates on the catalyst surfaces. These preliminary results provide guidance for the synthesis of more efficient Cu–ZnO catalysts and for the optimization of reaction parameters for selective glycerol hydrogenolysis to produce propylene glycol.     

新型MgCl_2负载钛催化剂在丙烯聚合中的应用

用优化乳化法制备了MgCl_2负载钛催化剂,考察了催化剂的形态结构并将其应用于丙烯催化聚合。聚合温度70℃、氢气加入量为1 L,采用二异丁基二甲氧基硅烷作为外给电子体时,催化剂具有较高的催化活性,同时聚丙烯具有较高的等规指数。     

Removal of trace boron from aqueous solution using iminobis-(propylene glycol) modified chitosan beads

In this paper, a new boron chelating chitosan based polymer with multi-hydroxyl iminobis (propylene glycol) (IBPG) functions was prepared. A cross-linked chitosan (CCTS) with 2.70 mmol g⁻¹ amine content was modified with excess amount of glycidol at pH 7 and boron chelating resin with IBPG functions (4.60 mmol g⁻¹) was obtained. The boron chelating ability of the resulting resin was investigated under different experimental conditions (pH, foreign ions). This prepared material was evaluated by FT–IR spectra and UV spectra analysis. The IBPG modified CCTS resin was demonstrated to have a boron loading capacity of 2.2 ± 0.05 mmol g⁻¹ within 45 min. Desorption and resin regeneration studies were carried out to determine the effectiveness of the synthesized resin with HCl and NaOH respectively. The adsorption test indicated that the chitosan based chelating resin with IBPG functions exhibited higher selectivity of boron (2.05 mmol g⁻¹) in the presence of foreign ions especially Fe(III).     

Effective synthesis of propylene carbonate from propylene glycol and carbon dioxide by alkali carbonates

Quantum-chemical calculations give insight in the experimentally observed higher rate of hydrogen–deuterium exchange for oxidized Ga/HZSM-5 over reduced Ga/HZSM-5. The reaction is computed to be more facile over reduced (Ga⁺) than over oxidized (GaO⁺) cations. The difference lies in the difficult formation of active GaH₂⁺ cations from Ga⁺ compared to facile hydrogen dissociation over GaO⁺ to give active GaHOH⁺ cations. Neutral gallium oxide clusters are shown to have a lower intrinsic activity than GaO⁺ cations.     

硅胶负载硫酸铁催化合成正辛醛1,2-丙二醇缩醛

研究了在硅胶负载硫酸铁(Fe2(SO4)3/SiO2)催化下,以正辛醛和1,2-丙二醇为原料催化合成正辛醛1,2-丙二醇缩醛。考察了醛醇摩尔比、反应时间、催化剂用量及其重复使用等因素对反应的影响,优化了反应条件。结果表明:正辛醛0.1 mol,n(正辛醛)∶n(1,2-丙二醇)=1.0∶1.1,催化剂用量为反应物总质量的1.0%,带水剂环己烷12 mL,回流反应3.0 h,正辛醛1,2-丙二醇缩醛的收率最高可达92.3%。     

Selective oxidation of propylene by O2 with visible light in a zeolite

Propylene and O₂ loaded into zeolite BaY were found to react upon irradiation with green or blue light in a single photon process. In situ monitoring by FT-infrared spectroscopy showed that allyl hydroperoxide is the predominant product at –100°C. At room temperature, acrolein, propylene oxide, and allyl hydroperoxide were observed in comparable amounts. The aldehyde and epoxide are shown to emerge from secondary thermal chemistry of the allyl hydroperoxide photoproduct. The selectivity in terms of the hydroperoxide photoproduct is very high (98% at room temperature) even at high propylene conversion. Diffuse reflectance spectra show that access to the mild oxidation path is made possible by a zeolite-induced shift of the propylene O₂ charge-transfer absorption from the UV into the visible region.     

气相色谱法检测湿巾中丙二醇的含量

称取一定量湿巾样品加乙醇超声提取后,离心过滤,采用气相色谱法检测湿巾中的丙二醇含量,外标法定量。结果表明:该法在2.50~200.00 mg/L质量浓度范围内线性关系良好,1,2-丙二醇的相关系数为0.9989,检测限为1.50 mg/L,RSD_A=2.32%,加标回收率为92.10%~97.20%;1,3-丙二醇的相关系数为0.9994,检测限为2.00 mg/L,RSD_A=3.15%,加标回收率为93.40%~97.25%。该方法前处理简便快捷,精密度、准确度、稳定性好,检测结果准确可靠。     

Highly selective synthesis of propylene glycol ether from methanol and propylene oxide catalyzed by basic ionic liquid

BACKGROUND: Propylene glycol ether is expected to be a safe substitute for toxic ethylene glycol ether usually used in industry owing to its negligible toxicity. Although catalysis of solid acids or bases for the synthesis of the ether can avoid separation of catalysts, liquid waste treatment and corrosion problems, it suffers from drawbacks, e.g. lower activity and selectivity to target product, high reaction pressure and temperature. In order to solve these problems, a basic ionic liquid, namely choline hydroxide was prepared and used as a catalyst for synthesis of the ether via atom‐economy reaction from propylene oxide and methanol. RESULTS: The ionic liquid showed excellent catalytic performance exhibiting 95.4% conversion of propylene oxide (PO) and 94.6% selectivity to 1‐methoxy‐2‐propanol. It is also an effective catalyst for the reaction of PO with other primary alcohols to yield corresponding ethers. In addition this catalyst can be recovered and reused. CONCLUSION: The high activity and selectivity can probably be ascribed to its basicity and/or the strong polarity and electrostatic field of the reaction medium caused by the ionic liquid. These findings are very rare in synthesis of propylene glycol ether to our knowledge. Copyright © 2010 Society of Chemical Industry     

Selective aerobic oxidations by supported ruthenium hydroxide catalysts

Aerobic oxidations of various alcohols, diols, and amines are efficiently promoted by the easily prepared inexpensive supported ruthenium hydroxide catalysts. A wide variety of substrates including aromatic, aliphatic, and heterocyclic ones can be converted into the desired products in moderate to excellent yields without the need for additives such as bases and electron/hydrogen transfer reagents. The catalysis for these reactions was intrinsically heterogeneous, and supported ruthenium hydroxide catalysts recovered after these reactions could be reused without appreciable loss of the catalytic performances. A reaction mechanism involving ruthenium alkoxide (amide) formation/β-elimination has been proposed for the present catalytic oxidations.     

Pressure-volume-temperature properties for binary and ternary polymer solutions of poly(ethylene glycol), poly(propylene glycol), and poly(ethylene glycol methyl ether) with anisole

Pressure-volume-temperature properties were measured for polymer solutions of poly(propylene glycol) (PPG)+anisole, polymer blends of PPG+poly(ethylene glycol methyl ether) (PEGME), and the blends of PPG+PEGME and poly(ethylene glycol) (PEG)+PPG with anisole at temperatures from 298.15 to 348.15 K and pressures up to 50 MPa. The Tait equation represents accurately the pressure effect on the liquid densities over the entire pressure range. The excess volumes change from positive to negative as increasing the mole fraction of PPG in the binary systems of PPG+anisole and PPG+PEGME. The volumetric data of the related binary systems were correlated with the Flory-Orwoll-Vrij and the Schotte equations of state to determine the binary parameters. By using these determined binary parameters, both equations predicted the specific volumes of the polymer blends with anisole to average absolute deviations of better than 0.13%.     

固载杂多酸催化剂PW_（12）／SiO_2复相催化合成二苯甲酸二甘醇酯

用自行研制的固载杂多酸催化剂ＰＷ１２／ＳｉＯ２复相催化酯化合成增塑剂二苯甲酸二甘醇酯（ＤＢＤＥ）。通过正交试验确定最佳工艺条件为：苯甲酸２５ｇ，二甘醇１２．０ｍｌ，带水剂甲苯１８ｍｌ，催化剂１．２５ｇ，反应温度（１３２±１）℃；反应时间３ｈ，在此条件下酯化率可达９９．８％。     

Selective hydrogenation by novel composite supported Pd egg-shell catalysts

Two organic–inorganic mixed phase supports were prepared, comprising an alumina filler and polymers of different chemical nature. Four low loaded Pd catalysts were prepared. Good activities and selectivities were obtained during the hydrogenations of styrene, 1-heptyne and 2,3-butanedione. The catalysts were found to have excellent mechanical properties and could be used in applications needing high attrition resistance and crushing strength. In this sense, processes for fine chemicals using slurry reactors or processes for commodities using long packed beds could advantageously use them.     

气相色谱法定量测定牙膏中的薄荷醇、丙二醇和甘油

建立了同时测定牙膏中薄荷醇、丙二醇和甘油含量的气相色谱法。以无水乙醇为溶剂在超声辅助下对8种牙膏样品进行预处理,采用6820型气相色谱仪,配19091X-233 WAX极性毛细管柱(30 m×250μm×0.25μm)进行测定。结果表明,检测的标准偏差为0.17～1.15 mg,平均回收率为89.5%～94.4%。     

Production of propylene glycol fatty acid monoesters by lipase-catalyzed reactions in organic solvents

Fatty acid monoesters of propylene glycol (1,2-propanediol) are good water-in-oil emulsifiers. These esters were synthesized enzymatically to overcome the problems associated with chemical processes. APseudomonas lipase was added to reaction mixtures containing propylene glycol and various acyl donors (fatty acids, fatty acid ethyl esters, fatty acid anhydrides and triglycerides) in organic solvents, and the mixtures were shaken at 30°C. The products were analyzed by gas chromatography. The yield of monoesters was affected by the acyl donors, organic solvents, temperature, water content, pH memory and reaction time. The anhydrous (lyophilized) enzyme and fatty acid anhydrides were best for monoester production. The optimum pH ranges were 4–5 and 8–10. The yields of propylene glycol monolaurate, monomyristate, monopalmitate, monostearate and monooleate with 50 mM fatty acid anhydrides as acyl donors were 97.2, 79.6, 83.7, 89.7 and 93.4 mM, respectively; those with 50 mM fatty acids as acyl donors were 37.3, 28.7, 28.7, 35.3 and 36.2 mM, respectively. The yields of propylene glycol monopalmitate, monostearate and monooleate with 50 mM triglycerides as acyl donors were 87.4, 65.1 and 83.2 mM, respectively.     

Control of polymer particle size by supported metallocene catalysts

By utilizing a pre-mixing method, we can prepare a supported metallocene catalyst producing a polyethylene of larger granular size and containing fewer fine particles than that prepared by the conventional adsorption of metallocene on a MAO-coated SiO_x surface. Such supported catalyst helps to eliminate the reactor fouling during polymerization of ethylene. This revised version was published online in July 2006 with corrections to the Cover Date.     

MgCl2‐supported catalyst containing mixed internal donors for propylene polymerization

A MgCl₂‐supported catalyst containing diisobutyl phthalate (DIBP) and 2,4‐pentadiol dibenzoate (PDDB) as internal donors was prepared. Propylene polymerizations were carried out using the catalyst in the absence or presence of an external donor. The resulting polymers were characterized by ¹³C‐NMR, crystallization analysis fraction (CRYSTAF) and gel permeation chromatography (GPC). The performance of the catalyst was compared with that of other catalysts containing donor‐free, DIBP and PDDB as internal donors respectively. The results demonstrated that the catalyst containing mixed internal donors not only had high activity and stereospecificity but also produced the polymer with relatively broad molecular weight distribution and the highest [mmmm] value. ¹³C‐NMR analysis results indicated that strongly coordinating donors gave more stereoregular polymers, which was further confirmed by CRYSTAF data. The effects of mixed internal donors on the catalyst properties were discussed systematically. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Molecular relaxation in cross-linked poly(ethylene glycol) and poly(propylene glycol) diacrylate networks by dielectric spectroscopy

The molecular relaxation characteristics of rubbery amorphous crosslinked networks based on poly(ethylene glycol) diacrylate [PEGDA] and poly(propylene glycol) diacrylate [PPGDA] have been investigated using broadband dielectric spectroscopy. Dielectric spectra measured across the sub-glass transition region indicate the emergence of an intermediate “fast” relaxation in the highly crosslinked networks that appears to correspond to a subset of segmental motions that are more local and less cooperative as compared to those associated with the glass transition. This process, which is similar to a distinct sub-T_g relaxation detected in poly(ethylene oxide) [PEO], may be a general feature in systems with a sufficient level of chemical or physical constraint, as it is observed in the crosslinked networks, crystalline PEO, and PEO-based nanocomposites.     

Synthesis of propylene glycol methyl ether over amine modified porous silica by ultrasonic technique

Amine modified porous silica were synthesized by ultrasonic technique under mild conditions. The samples, which were characterized by BET, ²⁹Si NMR spectra, element analysis and indicator dye adsorption, exhibited promising catalytic properties towards the synthesis of propylene glycol methyl ether from methanol and propylene oxide. They had both high yields and reusability in the reaction, indicating that ultrasonic technique was effective for the preparation of organically modified silica catalysts. Furthermore, the possible reaction mechanism was proposed for the synthesis of propylene glycol methyl ether over such type of catalysts.