Propylene Glycol Methyl Ether Research Articles

Optimization of liquid–liquid extraction combined with either heterogeneous azeotropic distillation or extractive distillation processes to reduce energy consumption and carbon dioxide emissions

The mixture of propylene glycol methyl ether and water form a minimum-boiling azeotrope. To separate the binary azeotropic system, energy-saving liquid–liquid extraction combined with either heterogeneous azeotropic distillation or extractive distillation processes based upon traditional two-column heterogeneous azeotropic distillation and three-column extractive distillation processes were proposed, using chloroform and 2-ethylhexanoic acid as solvents, respectively. The minimum total annual cost (TAC), based on a sequential iterative optimization procedure, and CO2 emissions for the two processes were determined. Liquid–liquid extraction combined with heterogeneous azeotropic distillation process achieved significant reductions of 40.24% in the TAC and 45.37% in CO2 emissions compared with the traditional two-column heterogeneous azeotropic distillation process. The liquid–liquid extraction combined with extractive distillation process achieved TAC and CO2 emission reductions of 34.18% and 43.95%, respectively, compared with the traditional three-column extractive distillation process. Thus, the two processes are more attractive in terms of both economics and environmental protection.

In Situ Spectroscopic and Computational Studies on a MnO2-CuO Catalyst for Use in Volatile Organic Compound Decomposition.

In situ near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and density functional theory calculations were conducted to demonstrate the decomposition mechanism of propylene glycol methyl ether acetate (PGMEA) on a MnO2–CuO catalyst. The catalytic activity of MnO2–CuO was higher than that of MnO2 at low temperatures, although the pore properties of MnO2 were similar to those of MnO2–CuO. In addition, whereas the chemical state of MnO2 remained constant following PGMEA dosing at 150 °C, MnO2–CuO was reduced under identical conditions, as confirmed by in situ NEXAFS spectroscopy. These results indicate that the presence of Cu in the MnO2–CuO catalyst enables the release of oxygen at lower temperatures. More specifically, the released oxygen originated from the Mn–O–Cu moiety on the top layer of the MnO2–CuO structure, as confirmed by calculation of the oxygen release energies in various oxygen positions of MnO2–CuO. Furthermore, the spectral changes in the in situ NEXAFS spectrum of MnO2–CuO following the catalytic reaction at 150 °C corresponded well with those of the simulated NEXAFS spectrum following oxygen release from Mn–O–Cu. Finally, after the completion of the catalytic reaction, the quantities of lactone and ether functionalities in PGMEA decreased, whereas the formation of C=C bonds was observed.

Sample preparation of chemical warfare agent simulants on a digital microfluidic (DMF) device using magnetic bead-based solid-phase extraction

In the present study, the purification and extraction of five chemical warfare agent (CWA) simulants, dimethyl methyl phosphonate, di(propylene glycol) methyl ether, methyl salicylate, triethyl phosphate, and diethyl phthalate, on a digital microfluidic (DMF) device were demonstrated. The DMF on-chip purification and extraction was performed using a magnetic bead (MB)-based diol solid-phase extraction procedure. The extracted CWA simulants were detected using both matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and gas chromatography-mass spectrometry (GC-MS). The method detection limits of the DMF-MS approach using diol-MBs were also determined. In particular, for the DMF-GC-MS, the quantitative analysis ability was validated by determining accuracy, precision, calibration curve performance, and recovery efficiency. This study clearly shows that the CWA analyses can be automated on the DMF-MS platform, thereby minimizing human involvement.

Relationship of basicity and hydrogen bond properties of ionic liquids with its catalytic performance: Application to synthesis of propylene glycol methyl ether

The relationship of basicity and hydrogen bond with catalytic performance was investigated in synthesis of propylene glycol methyl ether (PGME) catalyzed by various ILs ([Emim][OAC], [Bmim][OAC], [N2222][OAC], [EtOHN111][OAC], [N4444]Br, [Bmim][N(CN)2], [Bmim]Br, [Bmim][PF6]). The basicity and Kamlet-Taft parameters of each catalyst were evaluated by UV–visible spectroscopy. It was found the catalytic performance is the synergistic effect of basicity and hydrogen bond donating ability in the synthesis of PGME from PO and CH3OH, which is quite different from the conventional basic catalytic mechanism.

Isobaric Vapor–Liquid Equilibria for Two Binary Systems {Propylene Glycol Methyl Ether Acetate + Methanol} and {Propylene Glycol Methyl Ether Acetate + N,N-Dimethylformamide} at p = 30.0, 50.0, and 70.0 kPa

The isobaric vapor–liquid equilibria (VLE) data for two binary systems of propylene glycol methyl ether acetate (PMA) + N,N-dimethylformamide (DMF) and propylene glycol methyl ether acetate (PMA) + methanol (MeOH) at 30.0, 50.0, and 70.0 kPa were measured by utilizing a modified Rose–Williams still type apparatus which could be able to quickly form the dual cycle of continuous vapor and liquid phase in this work. On the basis of Herington area test and Van Ness point test, the thermodynamic consistency of the experiment data was verified. Meanwhile, VLE data that we obtained were correlated with nonrandom two-liquid (NRTL) and Margules activity coefficient models. The results demonstrated that the calculated values were in good conformity with the experimental data in this study. In addition, azeotropic behavior was observed in the binary system of PMA and DMF at reduced pressures.

Reactive Distillation for the Production of Methoxy Propyl Acetate: Experiments and Simulation

Propylene glycol methyl ether acetate is an industrially important solvent. In this work, we study the applicability of reactive distillation (RD) for its synthesis in the presence of an ion-exchange resin, Amberlyst 15, as a catalyst. Simultaneous separation of water during the course of reaction shifts the reaction in the forward direction, which renders cost effectiveness and compactness to the process. The presence of an azeotrope between methoxy propanol and water complicates the separation, leading to a loss of reactants in the product streams, thereby hampering both conversion and purity. Toluene is thus used as an entrainer to further intensify the process. In this work, the intrinsic kinetic parameters are determined from batch reactor data, and used subsequently to simulate the column performance. An experimentally validated simulator is used to examine the effect of various operating and design parameters. Reactant and product losses are minimized to negligible levels and a significant increase...

Synthesis of yellow pyridonylazo colorants and their application in dye–pigment hybrid colour filters for liquid crystal display

Nine yellow azo dyes were designed and synthesised by using different diazo components and pyridonyl coupling components for application in dye–pigment hybrid colour filters for liquid crystal displays. The synthesised dyes were characterised by proton nuclear magnetic resonance and elemental analysis. The thermal stability was examined by thermogravimetric analysis, and solubility was estimated in industrial solvents such as N‐methyl‐2‐pyrrolidone and propylene glycol methyl ether acetate. The dyes, which exhibited suitable physical properties for use in a dye–pigment hybrid colour filter, were fabricated into colour filters, and their optical properties were measured.

Preparation and shaping of solid acid SO42−/TiO2 and its application for esterification of propylene glycol monomethyl ether and acetic acid

Abstract The solid acid SO42 −/TiO2 was prepared by immersion method and applied for synthesis of propylene glycol methyl ether acetate (PMA) through esterification reaction of propylene glycol monomethyl ether (PM) and acetic acid (HAc). The optimal catalyst preparation condition was determined by orthogonal analysis of parameters in a five-factor and four-level test. The obtained solid acid catalysts were characterized in detail by means of X-ray powder diffraction, thermogravimetry, pyridine adsorbed IR analysis, scanning electron microscopy, and BET surface area method. Synthesis of PMA was studied in this paper through experimental investigation of reaction conditions such as temperature, molar ratio of reactants, catalyst dosage and agitation speed. Based on its possible reaction mechanism, a pseudo-homogeneous kinetic model was established and its activation energies Ea+ and Ea−, 65.68 × 103 J·mol− 1 and 57.78 × 103 J·mol− 1, were estimated. To prepare shaped solid acid catalyst SO42 −/TiO2, the shaping method of impregnation–shaping–impregnation was applied. The optimal molding formulation of solid acid catalyst, obtained from the orthogonal test, was found to be binder 7 wt.%, reinforcing agent 20 wt.%, pore forming material 2.5 wt.%, and lubricant 4 wt.%. The results of performance test of catalyst demonstrated that the shaped solid acid catalyst exhibited high activity and stability.

Controlling organization of conjugated polymer films from binary solvent mixtures for high performance organic field-effect transistors

We investigate the effect of a binary solvent blend as a solvent for poly{[N,N′-bis(2-octyldodecyl)-1,4,5,8-naphthalenediimide-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)} P(NDI2OD-T2) on the characteristics of n-channel organic field-effect transistors (OFETs). To make the binary solvent blend, the low-boiling-point non-solvent propylene glycol methyl ether acetate (PGMEA, b.p ∼146 °C) is added to the high-boiling-point good solvent 1,2-dichlorobenzene (O-DCB, b.p ∼180 °C) at various mixing ratio from 0 to 40 v%. UV–vis spectra of P(NDI2OD-T2) solution dissolved in the binary solvent clearly show the formation of polymer aggregates through a gradual red shift of the intramolecular charge transfer band with the addition of high concentrations of non-solvent PGMEA. Higher edge-on oriented crystallinity is observed for P(NDI2OD-T2) films spin-coated from the binary solvent with 5–10 v% PGMEA by out-of-order x-ray diffraction. P(NDI2OD-T2) films are applied as the active layer in top-gate/bottom-contact OFETs. Improved n-type field-effect mobility of the P(NDI2OD-T2) semiconducting layer up to 0.59 cm2/Vs was achieved for on-center spin coated films compared to 1.03 cm2/Vs for off-center (parallel alignment) spin-coated films respectively employing the binary solvent with 10 v% PGMEA.

Transesterification of propylene glycol methyl ether in chromatographic reactors using anion exchange resin as a catalyst

Reactive chromatography using an anion exchange resin is proposed for a transesterification reaction of propylene glycol methyl ether (DOWANOL™ PM) with ethyl acetate to produce propylene glycol methyl ether acetate (DOWANOL™ PMA). This reaction is studied in batch and chromatographic reactors catalyzed by an anion exchange resin. Several anion exchange resins are tested and compared based on the performance of resin as an adsorbent and a catalyst. A chromatographic column is packed with a selected catalyst, AMBERLITE™ IRA904, and both reaction and chromatographic elution are studied at different temperatures and feed concentrations. The resulting chromatograms are fitted to a mathematical model to obtain adsorption equilibrium and reaction kinetic parameters by the inverse method. Compared to esterification investigated in a previous study, transesterification has advantages such as a higher conversion at lower temperature and easy removal of the byproduct which may lead to higher productivity. Deactivation of anion exchange resins is observed and potential solutions are suggested.

Controlled airbrush coating of polymer resists in Roll-to-Roll nanoimprinting with regimented residual layer thickness

We study the effective resist dispensing in continuous Roll-to-Roll (R2R) nanoimprinting system by using a simple and controlled airbrush coating method. Compared to common spin-coating or drop-casting, airbrushing can better afford the continuous coating operation required in a R2R nanoimprinting system with controlled thickness and uniformity. We use a UV-curable epoxysilsesquioxane (SSQ) and propylene glycol methyl ether acetate (PGMEA) as a concentration control agent, which are airbrushed for a controlled time over a continuously fed flexible or rigid substrate in a R2R conveyer. The R2R nanoimprinting is successfully conducted with uniform pattern quality. By modulating the airbrushing time and resist concentration, the residual layer thickness (RLT) of R2R-imprinted patterns can be readily controlled for specific uses.

Comparison of heteroazeotropic and extractive distillation for the dehydration of propylene glycol methyl ether

Separation section often is the most energy intensive section of an industrial chemical process, even so when there is an azeotropic mixture needed to be separated. In order to further save energy in a particular azeotropic separation system, various heat integration methods were proposed. However, because of more complex nature of these heat integration methods, the operation and control of such process may be hindered. Since there are various ways which can be used to separate a particular azeotropic mixture, this paper uses an industrial relevant propylene glycol methyl ether dehydration system as an example to demonstrate that selecting the most effective separation method is crucially important in attempting to save energy of the separation system. The drawback of using heterogeneous azeotropic distillation for this separation task can easily be revealed with process understanding. A more effective separation method via extractive distillation is proposed to significantly save steam cost by 39.7% and reduce the total annual cost by 32.7%. Simple feed-effluent heat exchanger can be added in the proposed extractive distillation system to further save energy without much complication of the process design flowsheet.

Model-based design and experimental validation of simulated moving bed reactor for production of glycol ether ester

This work proposes a practical and systematic model-based approach to identify the optimal operating conditions for a simulated moving bed reactor (SMBR). The SMBR operation is applied to an industrial case study for the continuous production of a solvent, propylene glycol methyl ether acetate (DOWANOL™ PMA), which is produced through an acid-catalyzed esterification reaction of 1-methoxy-2-propanol and acetic acid.The model-based approach is demonstrated by lab-scale SMBR experiments. A multi-objective optimization problem was formulated for developing an SMBR process to maximize the production rate of PMA and the conversion of the esterification reaction simultaneously. In this study, this optimization problem is solved using the epsilon-constrained method and a Pareto plot is presented. The solutions that corresponded to three different values of conversion, 70%, 80%, and 85%, are experimentally validated. The SMBR model that was developed from batch kinetic and single column chromatography experiments demonstrates reasonable agreement with the experimental results. Furthermore, the SMBR experimental data was used to correct the parameters in the model. A validation study at a higher conversion of 95% demonstrates improved predictability of the corrected parameters.

Preparation and characterization of sulfated TiO2 with rhodium modification used in esterification reaction and decomposition of methyl orange

A unique Rh/TiO2 solid acid catalyst modified with H2SO4 was synthesized and evaluated in the esterification reaction of propylene glycol methyl ether and decomposition of methyl orange (MO) in aqueous phase under halogen lamp irradiation. For this purpose, rhodium (Rh) nanoparticles were loaded on SO42−/TiO2via the photo-deposition method. It was found that SO42−/Rh–TiO2 exhibited stronger catalytic activity than SO42−/TiO2. The new catalysts were characterized by X-ray powder diffraction (XRD), Brunauer–Emmett–Teller (BET), Transmission electron microscopy (TEM) and high-resolution (HRTEM), X-ray photoelectron spectroscopy (XPS) and Fourier Transform infrared spectroscopy (FTIR). Results from XRD and BET show that SO42−/Rh–TiO2 has higher specific surface area and smaller pore size than SO42−/TiO2. The distribution of loaded Rh was found to be uniform with a particle size of 2–4nm. Data from XPS reveal that Rh primarily exists as Rh0 and Rh3+ in Rh–TiO2 and SO42−/Rh–TiO2. These valence forms of Rh likely contribute to the enhanced catalytic activity. Furthermore, FT-IR spectra of the catalysts show an abundance of surface hydroxyl groups, which help the formation of hydroxyl radicals and the enhancement of surface acid density. The results show that more acid sites are formed on the sulfated Rh–TiO2, and these acidic sites are largely responsible for improving the catalytic performance. This superior SO42−/Rh–TiO2 catalyst has potential applications in reactions requiring efficient acid catalysts, including esterification reactions and waste water treatment.

Monitoring of organic contamination in the ambient air of microelectronic clean room by proton-transfer reaction/time-of-flight/mass spectrometry (PTR–ToF–MS)

The organic contamination has been recently considered as the most important problem for the photolithography world in the semiconductor industry, especially when the photolithographic methods moved from 130nm node to 32nm node. One of the most common organic compounds found in photolithography areas of the clean room is Trimethylsilanol (TMS), which can adsorb on the optical lenses forming a thin molecular layer, hence causing damages. Salt crystal formation is another potential threat for the optical devices. In the clean rooms, this salt is produced by a light-induced reaction between ammonia and an acid. In the context of semiconductor industry, the involved acid is usually the acetic acid produced by hydrolysis from propylene glycol methyl ether acetate (PGMEA), a commonly used organic compound in the photolithography.Here, we present an innovative analytical method using a state-of-the-art proton-transfer reaction–time-of-flight–mass spectrometer (PTR–ToF–MS) for on-line and continuous survey of volatile organic compounds (VOCs) with an emphasis on TMS and PGMEA. The effect of relative humidity on the detection and fragmentation of these organic compounds was assessed. The new analytical method is operated in a real life clean room environment and the results were compared with those obtained with off-line measurements using automated thermal desorber–gas chromatography–mass spectrometry (ATD–GC–MS) as reference method.The contamination sources were detected and identified, which is of paramount importance for the microelectronic fabrication plant. The trapping efficiency of the chemical filters used for AMCs filtration in the photolithography zone was determined.

Deriving Biomonitoring Equivalents for selected E- and P-series glycol ethers for public health risk assessment.

Glycol ethers are a widely used class of solvents that may lead to both workplace and general population exposures. Biomonitoring studies are available that have quantified glycol ethers or their metabolites in blood and/or urine amongst exposed populations. These biomonitoring levels indicate exposures to the glycol ethers, but do not by themselves indicate a health hazard risk. Biomonitoring Equivalents (BEs) have been created to provide the ability to interpret human biomonitoring data in a public health risk context. The BE is defined as the concentration of a chemical or metabolite in a biological fluid (blood or urine) that is consistent with exposures at a regulatory derived safe exposure limit, such as a tolerable daily intake (TDI). In this exercise, we derived BEs for general population exposures for selected E- and P-series glycol ethers based on their respective derived no effect levels (DNELs). Selected DNELs have been derived as part of respective Registration, Evaluation, Authorisation and Regulation of Chemicals (REACh) regulation dossiers in the EU. The BEs derived here are unique in the sense that they are the first BEs derived for urinary excretion of compounds following inhalation exposures. The urinary mass excretion fractions (Fue) of the acetic acid metabolites for the E-series GEs range from approximately 0.2 to 0.7. The Fues for the excretion of the parent P-series GEs range from approximately 0.1 to 0.2, with the exception of propylene glycol methyl ether and its acetate (Fue = 0.004). Despite the narrow range of Fues, the BEs exhibit a larger range, resulting from the larger range in DNELs across GEs. The BEs derived here can be used to interpret human biomonitoring data for inhalation exposures to GEs amongst the general population.

Synthesis and characterization of bay-substituted perylene dyes for LCD black matrix of low dielectric constant

Organic dyes with low electrical conductivity have recently been suggested as replacements for Cr/CrOx and carbon black in developing black matrices with low dielectric constants for liquid crystal displays (LCDs). Two perylene diimide dyes with broad absorption spectra were synthesized, and dye-type, hybrid-type and carbon black-type black matrices were fabricated using one of the dyes. Donating groups were substituted on the bay positions of the dyes by C–N coupling to enhance their solubility in propylene glycol methyl ether acetate, one of the most widely used industrial solvents in the LCD manufacturing processes. The thermal and spectral properties of the dyes were studied by thermogravimetric analysis and UV–Visible spectroscopy. Furthermore, the thermal, optical and dielectric properties of the black matrices were examined by color spectroscopy, optical density measurement and impedance analysis. The hybrid-type black matrix showed promising results with a low dielectric constant, low transmittance spectrum and high thermal stability.

Synthesis and characteristics of metal-phthalocyanines tetra-substituted at non-peripheral (α) or peripheral (β) positions, and their applications in LCD color filters

Four metal-phthalocyanine dyes were synthesized to evaluate the variation of their properties with both the position of the substituents and the type of metal used for coordination. The substituent, ethyl 4-hydroxy-3-methoxybenzoate, was introduced at the non-peripheral (α) or the peripheral (β) position in order to improve the solubility of the phthalocyanine. Cu and Zn were chosen as coordination metals, both to increase thermal stability and to fine-tune the color of the complex. The resulting complexes were highly soluble in a range of organic solvents as well as industrial solvents, such as di(propylene glycol) methyl ether acetate, diethylene glycol monobutyl ether acetate, and propylene glycol methyl ether acetate. The solubility of the dyes substituted at the α-position was higher than that of β-substituted dyes. Structural analyses of the substituted phthalonitriles were achieved using 1H and 13C NMR spectroscopy, and high-resolution mass spectrometry. The structures of the dyes were confirmed by MALDI-TOF spectroscopy and FT-IR spectrophotometry. The optical properties and thermal stabilities of the dyes were estimated by UV–Vis spectrophotometry and thermogravimetric analysis. The synthesized dyes were cyan in color, and thus could be successfully applied in six-primary-color (RGBCMY) liquid crystal display (LCD) color filters in order to improve the color gamut. Dye-based color filters showing adequate optical spectra for LCD cyan color filters were manufactured. Appropriate compensating dyes were also required in order to cut off undesirable transmittance peaks.

PDMS residues-free micro/macrostructures on flexible substrates

Transfer printing has been reported recently as a viable route for electronics on flexible substrates. The method involves transferring micro-/macrostructures such as wires or ultra-thin chips from Si (silicon) wafers to the flexible substrates by using elastomeric transfer substrates such as poly(dimethylsiloxane) (PDMS). A major challenge in this process is posed by the residues of PDMS, which are left over on Si surface after the nanostructures have been transferred. As insulator, PDMS residues make it difficult to realize metal connections and hence pose challenge in the way of using nanostructures as the building blocks for active electronics. This paper presents a method for PDMS residues-free transfer of Si micro-/macrostructures to flexible substrates such as polyimide (PI). The PDMS residues are removed from Si surface by immersing the transferred structures in a solution of quaternary ammonium fluoride such as TBAF (Tetrabutylammonium Fluoride) and non-hydroxylic aprotic solvent such as PMA (propylene glycol methyl ether acetate). The residues are removed at a rate (∼1.5μm/min) which is about five times faster than the traditional dry etch methods. Unlike traditional alternatives, the presented method removes PDMS without attacking the flexible PI substrates.

Foaming and gas dispersion properties of non-ionic frothers in the presence of hydrophobized submicron particles

Foams represent an important area of research due to their relevance in many industrial processes. In many systems, particulates and surfactants co-exist and can largely define the stability of the foam. A typical example is froth flotation where hydrophobic particles and frothers are essential to maintain a stable froth. Grinding operations may yield a product containing submicron-size particles, which can affect the flotation process. The present study compares the foaming and gas dispersion properties of the non-ionic surfactants 1-pentanol, tri(propylene glycol) methyl ether, and poly(propylene glycol) 425 in the presence of hydrophobic colloidal silica particles in a column. In all cases, it has been found that the gas holdup increases proportionally with the increase in the concentration of particles in the system although an initial decrease may be observed. The effect of particles on the foaminess seems to be dependent upon the surfactant. With the 1-pentanol, the addition of particles systematically decreased the foaminess of the solutions. This is in contrast to poly(propylene glycol) solutions, which exhibited an increase. Interestingly, low concentrations of particles appeared to improve the foaminess of tri(propylene glycol) methyl ether; however, the froth became less stable with further increases in the number of particles in the column. Visual observation showed that the colloidal particles play a crucial role in defining the quality of the structure of the froth.