Hydroformylation of formaldehyde to glycolaldehyde:An alternative synthetic route for ethylene glycol

Hydroformylation of formaldehyde to glycolaldehyde (GA),as a vital reaction in both direct and indirect process of syngas to ethylene glycol (EG),shows great advantages in the aspects of the process complex-ity and clean production.The hydroformylation of formaldehyde to GA is thermodynamically unfavour-able,requiring the development of highly efficient hydroformylation catalytic systems,appropriate reaction conditions and in-depth understanding of the reaction mechanisms.In this review,we have made a detailed summary on the reaction in terms of the reaction network,thermodynamics,metal com-plex catalysts (including central metals and ligands),reaction conditions (e.g.,temperature,pressure,formaldehyde source and solvent) and promoters.Furthermore,the reaction mechanisms,involving neu-tral and anionic complex in the catalytic cycle,have been summarized and followed by a discussion on the impact of the crucial intermediates on the reaction pathways and product distribution.A brief over-view of product separation and catalyst recovery has been presented in the final part.This review gives new insights into the factors that impact on the formaldehyde hydroformylation and reaction mecha-nisms,which helps to design more efficient catalytic systems and reaction processes for EG production via the hydroformylation route.     

One-pot synthesis of ethylene glycol and its mono-methyl ether from ethylene using Al-TS-1 catalyst

Ethylene glycol (EG) and its mono-methyl ether (MME) were synthesized directly from ethylene and hydrogen peroxide under mild conditions using Al–TS-1 as the bifunctional catalyst. The progressive incorporation of Al into the framework increased the catalytic capacity of Al–TS-1 until a maximum was reached (SiO₂/Al₂O₃ molar ratio: 504), whereas further Al incorporation decreased the catalytic activity to even lower values than in TS-1. Under the optimum conditions, the conversion and utilization of H₂O₂ reached 95% and 90%, respectively, while the total concentration of EG and MME reached to above 10 wt.%.     

乙二醇市场供需分析

综述了国内外乙二醇的生产发展、供需和消费结构;预测了我国乙二醇的生产和需求;根据目前我国乙二醇的生产状况和存在的问题,提出了发展建议。     

Effect of ethylene glycol on the mullite crystallization

Mullite is one of the most important aluminosilicate due to its unique thermal properties. In this work, mullite was obtained by sol-gel process at low temperature using sodium metasilicate, water, aluminum nitrate and ethylene glycol. The samples were prepared with a volume ratio of ethylene glycol/water equal to 0/1, 1/1, 2/1 and 3/1. The ethylene glycol effect on mullite crystallization was studied by X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), Scanning Electron Microscopy (SEM) and Differential Thermal Analysis (DTA). The sample prepared without ethylene glycol, the less homogeneous one, formed amorphous silica, spinel-phase and α-alumina at 1000 °C, and then crystallized mullite at 1200 °C, with an alumina molar fraction of 0.58. The other samples formed amorphous silica at 900 °C and crystallized mullite as the only crystalline phase at 1000 °C. However, the alumina content in mullite formula depends on the thermal treatment, reaching 0.58 at 1250 °C.     

环氧乙烷催化水合生产乙二醇工艺技术研究

非催化水合生产乙二醇工艺具有能耗大、成本高的缺点。笔者采用树脂类催化剂进行了环氧乙烷化水合生产乙二醇工艺技术研究,并考察了温度、空速、n(H2O)∶n(EO)、压力及进料方式等工艺条件对催化剂性能的影响,催化剂经过了800 h稳定性考察,研究结果表明,在温度100℃、压力1.0MPa、空速1.5 h-1、n(H2O)∶n(EO)=6.5条件下,不仅具有很稳定的性能,而且环氧乙烷(EO)转化率和乙二醇(EG)选择性最高都可以达到100%。     

Effects of anodization parameters on the formation of titania nanotubes in ethylene glycol

The effects of fluoride concentration, anodization temperature, and anodization applied potential difference on the formation and dimensions of the titania nanotubes in ethylene glycol/water systems were investigated. It was found that fluoride concentration and anodization temperature were the two critical parameters for controlling the nanotube formation whilst anodization applied potential difference mainly contributes to tuning the dimension of the nanotubes. Electrolytes containing a low fluoride concentration are beneficial for initiating nanotube formation, whilst a higher anodization temperature is helpful to the rapid growth of the nanotubes. It is shown that the current-time curve obtained during the anodization can be used as an effective tool to predict the morphology of titania nanotubes. A model based on the competition between electrochemical oxidation of the titanium and chemical dissolution by fluoride ions is developed to explain the experimental observations.     

贵州发展煤制乙二醇项目的研究

本文介绍了乙二醇目前国内生产、技术和市场现状,并根据贵州的能源结构情况、资源优势、区位优势等阐述了在贵州发展煤制乙二醇项目的可行性。     

Removal of naphthenic acids from a vacuum fraction oil with an ammonia solution of ethylene glycol

A new method to remove and purify the naphthenic acids in heavy fractions of petroleum is studied in this paper. An ammonia solution of ethylene glycol was used as the acid removal reagent by mixing with the petroleum fraction and then allowing the two phases to separate, with the naphthenic acids being extracted from petroleum fractions. The naphthenic acids were recovered by heating the ammonia solution containing naphthenic acids to release NH₃ and decompose the naphthenic acid ammonia salt. Petroleum ether was used to purify the naphthenic acids by extracting the neutral oils from the acid removal reagent. Data indicated that the optimal extraction temperature was in the range of 50–60 °C and the optimal NH₃ content in ethylene glycol was 3–5%. The contact time should be more than 10 min with the reagent/oil ratio being more than 0.3 (wt/wt). Acid removal can be greater than 85%. After purification by petroleum ether, the purity of naphthenic acids can be greater than 90%.     

On the electrocatalysis of ethylene glycol oxidation

In the present paper, PtRu electrodes are used to study the electrooxidation of ethylene glycol (EG) in acid medium. The voltammetric results show that current-potential curves are shifted by about 0.2 V towards more negative potentials through the promoting effect of Ru on Pt. As in the case of pure platinum, FTIR spectra on PtRu surfaces prove that CO₂, glycolic acid and, possibly, oxalic acid are formed in parallel reactions. The catalytic activity, measured as the current density at constant potential, increases with the Ru content. But the complete oxidation of EG to CO₂ is favored by a high Pt content. In order to compare the catalytic activity of different PtRu compositions, currents measured at electrodeposited electrodes are normalized using the data for the oxidation of a CO monolayer.Results of a test using a laboratory PEM EG/O₂ cell with Pt:Ru (50:50) are presented.     

Anodic dissolution of titanium in chloride-containing ethylene glycol solution

Anodic dissolution behavior of titanium in chloride-containing ethylene glycol was examined using a rotating disk electrode. A potential-independent dissolution current flowed depending on the rotation speed, species and concentration of chloride salts. In solutions with lower concentrations of chloride, a potential-independent current was controlled not only by the mass transfer process but also by the charge transfer, and the kinetic-controlling current depends on solution conductivity. In concentrated chloride solutions, the current was controlled only by mass transfer process and decreased with increase in chloride concentration. A smaller current also flowed in a solution with a high concentration of titanium species. These results indicated that the diffusion-controlling species are titanium species, not chloride ions. Electrochemical impedance spectroscopy revealed that a titanium chloride salt layer, which maintains titanium species at a high concentration, accumulates a low charge (0.1 μF cm⁻²) and becomes thicker with increase in applied potential, is formed between the titanium substrate and diffusion layer during the mass transfer-controlling dissolution.     

Pervaporation dehydration of ethylene glycol by NaA zeolite membranes

Home-made NaA zeolite membranes were used for pervaporation dehydration of ethylene glycol (EG)/water mixtures. Hydrothermal stability of the membranes in pervaporation was investigated for industrial application purpose. The membranes exhibited good stability for water content of less than 20 wt.% at 100 °C. The reduction of operating temperature was effective to improve membrane stability for operating at high feed water content (e.g. 30 wt.%). The influence of feed water content and operating temperature on dehydration of EG was extensively investigated. A permeation flux of 4.03 kg m⁻² h⁻¹ with separation factor of >5000 was achieved at 120 °C for the separation of the solution with 20 wt.% water content. A pilot-scale pervaporation facility with membrane area of 3 m² was built up for dehydration of EG with the water content of 20 wt.%, which showed technical feasibility for industrial application.     

Comprehensive study of the role of ethylene glycol when preparing Ag@SBA-15 in supercritical CO2

Well-defined Ag nanowires were obtained in SBA-15 at a short deposition time of 5 min in supercritical CO₂ when adding a small amount of ethylene glycol as the co-solvent. Ethylene glycol played a key role in dictating the nanowire morphology. Through detailed investigation of the whole deposition process, including the dissolution of precursor assisted by the co-solvent, the diffusion properties of the precursor into the nano-scale channels of the substrate, and the interaction between the precursor and the substrate, we found that a small amount of precursors were reduced into Ag⁰ by ethylene glycol at the initial stage of the deposition. The resultant Ag⁰ then acted as nuclei leading to a non-equilibrium sorption of the precursor. The rapid adsorption of the precursor onto the substrate resulted in a high loading of Ag in a short deposition time and the formation of nanowire morphology. Furthermore, this method was successfully extended to other porous substrates such as γ-Al₂O₃, SiO₂ and KIT-6, demonstrating its great potentials in the synthesis of nanocomposites.     

Pt-modulated Cu/SiO2 catalysts for efficient hydrogenation of CO2-derived ethylene carbonate to methanol and ethylene glycol

Copper-based catalysts were widely used in the heterogeneous selective hydrogenation of ethylene car-bonate (EC),a key step in the indirect conversion of CO2 to methanol.However,a high H2/EC molar ratio in feed is required to achieve favorable activity and the methanol selectivity still needs to be improved.Herein,we fabricated a series of Pt-modulated Cu/SiO2 catalysts and investigated their catalytic perfor-mance for hydrogenation of EC in a fixed bed reactor.By modulating the Pt amount,the optimal 0.2Pt-Cu/SiO2 catalyst exhibited the highest catalytic performance with ～99％ EC conversion,over 98％ selectiv-ity to ethylene glycol and 95.8％ selectivity to methanol at the H2/EC ratio as low as 60 in feed.In addition,0.2Pt-Cu/SiO2 catalyst showed excellent stability for 150 h on stream over different H2/EC ratios of 180-40.It is demonstrated a proper amount of Pt could significantly lower the H2/EC molar ratio,promote the reducibility and dispersion of copper,and also enhance surface density of Cu+ species.This could be due to the strong interaction of Cu and Pt induced by formation of alloyed Pt single atoms on the Cu lattice.Meanwhile,a relatively higher amount of Pt would deteriorate the catalytic activity,which could be due to the surface coverage and aggregation of active species.These findings may enlighten some fundamen-tal insights for further design of Cu-based catalysts for the hydrogenation of carbon-oxygen bonds.     

乙二醇的生产方法与市场前景概述

介绍了乙二醇的制备方法和市场前景,并对我国乙二醇今后的生产提出了科学的见解,改变现阶段乙二醇生产方法的弊端,达到减少能源消耗、降低成本的目的,从而满足对乙二醇不断增长的需要.     

Simultaneous synthesis of dimethyl carbonate and ethylene glycol dimethacrylate using homogenous basic catalyst

A novel method simultaneously to prepare dimethyl carbonate and ethylene glycol dimethacrylate from ethylene carbonate and methyl methacrylate has been demonstrated in the presence of catalyst sodium methoxide and polymerization inhibitor ZJ-705. The effect of reaction parameters such as catalyst loading, polymerization inhibitor loading, concentration of reactants, reaction time, etc., on synthesis of dimethyl carbonate and ethylene glycol dimethacrylate was investigated. A reaction mechanism has been discussed with catalyst sodium methoxide.     

Electrochemical corrosion behavior of AZ91D alloy in ethylene glycol

The effect of concentration on the corrosion behavior of Mg-based alloy AZ91D was investigated in ethylene glycol–water solutions using electrochemical techniques i.e. potentiodynamic polarization, electrochemical impedance measurements (EIS) and surface examination via scanning electron microscope (SEM) technique. This can provide a basis for developing new coolants for magnesium alloy engine blocks. Corrosion behavior of AZ91D alloy by coolant is important in the automotive industry. It was found that the corrosion rate of AZ91D alloy decreased with increasing concentration of ethylene glycol. For AZ91D alloy in chloride >0.05 M or fluoride <0.05 M containing 30% ethylene glycol solution, they are more corrosive than the blank (30% ethylene glycol–70% water). However, at concentrations <0.05 for chloride or >0.05 M for fluoride containing ethylene glycol solution, some inhibition effect has been observed. The corrosion of AZ91D alloy in the blank can be effectively inhibited by addition of 0.05 mM paracetamol that reacts with AZ91D alloy and forms a protective film on the surface at this concentration as confirmed by surface examination.     

Structure alterations of perfluorinated sulfocationic membranes under the action of ethylene glycol (SAXS and WAXS studies)

Small-angle X-ray scattering and wide-angle X-ray scattering studies were carried out for perfluorinated sulfocationic membranes MF-4SK (membranes of a Nafion type) in the normal ‘as-manufactured’ state and soaked in ethylene glycol at 110 °C and subsequently washed with water. It was shown that such a treatment of MF-4SK membranes resulted in alterations of their nanostructure and these alterations were stable for a long time. On the basis of the paracrystalline layered model of the perfluorinated membrane nanostructure these structure alterations were interpreted as an increase in the thickness of the liquid layers (ionic channels) separating clusters of ionomer groups in MF-4SK membranes. The importance of these structure alterations was confirmed by the twofold growth of the quantum yield of anthracene photo-oxidation catalyzed by tetraphenylporphyrin (TPP) immobilized on MF-4SK membranes treated with ethylene glycol.     

Simulation of Doxorubicin Delivery via Glucosamine(ethylene glycol) Carrier

This article focuses on the molecular modeling of the release of doxorubicin from capsules composed of glucosamine(ethylene glycol) oligomers. Doxorubicin forms micelle structures with glucosamine(ethylene glycol), and the drug release mechanism can be studied through the modeling of oligomeric bond breaking under acidic, neutral, or basic conditions. Under these conditions, the activation energies were calculated to be 145.51, 135.78, and 287.60 kcal/mol, respectively, at the B3LYP/6-31G//PM3 level. Based on these values, doxorubicin can be released into acidic and neutral solutions but not into basic solution. Ethylene glycol chain length in glucosamine(ethylene glycol) also effects drug release. As the length of ethylene glycol increases, the amount of drug released increases under acidic conditions, but decreases under neutral and basic conditions. When the drug is released from glucosamine(ethylene glycol) oligomers, the drug molecule and glucosamine(ethylene glycol) molecules form a micelle structure. Studies found that, as the length of the ethylene glycol chains increases, the micelle structure is more easily formed. The ethylene glycol group can deliver doxorubicin to cancer cells in micelle form.     

环氧乙烷法合成乙二醇的技术创新

乙二醇（EG）是一种重要的基础化工原料,乙二醇工业涉及国民经济的多个领域,对支撑国民经济基础产业和战略新兴产业具有重大战略意义。本文简要阐述了环氧乙烷法生产乙二醇的技术进展,着重介绍了离子液体催化环氧乙烷生产乙二醇的创新工艺（ILC工艺）。该工艺是我国具有自主创新知识产权和自主运作权的乙二醇新技术,具有工艺简单、水比低、节能效果显著、原料适应性强、产品结构可调等优点,与现有乙二醇工业装置有良好相嵌性,推广应用前景广阔。甲醇制烯烃技术（MTO）的推广应用和多套EO/EG装置的投产使环氧乙烷的原料价格更加低廉,而且石化企业具有几十年大型装置的生产经验,因此,采用创新性技术以环氧乙烷为原料生产乙二醇的路线将在为今后较长的时期占主导地位。     

Investigation of three types of catalysts for the hydration of ethylene oxide (EO) to monoethylene glycol (MEG)

Amine compounds, bi-functional compounds (EDTA, ethylene diamine tetra acetic acid type), and Salen compounds were investigated for catalytic hydration of ethylene oxide (EO) to monoethylene glycol (MEG). Many of the catalysts studied are selective for the formation of MEG compared with thermal hydration without any catalyst present. The results of the catalytic hydration with three types of catalysts were rationalized using acid and base catalyzed reaction mechanisms.