Ethyl Tert-butyl Ether Research Articles

Ozonation and combined ozone/H2O2, UV/ozone and UV/H2O2 for treatment of fuel oxygenates MTBE, ETBE, TAME, and DIPE from water – a comparison of removal efficiencies

Methyl tert-butylether (MTBE) used as fuel oxygenate poses problems for water suppliers since it is persistent in the aquatic environment and the removal efficiency by conventional water treatment methods (aeration or activated carbon filtration) is rather low. Substitution by other ether compounds such as ethyl tert-butylether (ETBE), tert-amylmethylether (TAME) or di-isopropylether (DIPE) is discussed, however, their environmental behaviour is similar to that of MTBE. Experiments investigating the elimination efficiency of AOP were carried out in tap water and water from Lake Constance. The elimination efficiency for all treatment processes was found to follow the order: MTBE << TAME approximately equal ETBE < DIPE For all compounds under investigation, neither pure ozonation nor UV irradiation yield a considerable concentration decline. Only the formation of highly reactive OH radicals shows a potential for removing the ethers from water. Therefore the addition of H2O2 in equimolar ratio prior to ozone admixing proved to be quite efficient. The application of combined UV/H2O2 showed good results in all cases; the best concentration decline was achieved with UV/ozone. The rate of elimination of the three substitutes for MTBE (ETBE, TAME and DIPE) is higher in all processes; nevertheless, no complete removal could be achieved. Therefore, from the point of view of water suppliers, the use of other ethers as substitute for MTBE is posing the same problems as MTBE.

Temperature influence on mixing properties of {ethyl tert-butyl ether (ETBE) + gasoline additives}

The densities and ultrasonic velocity of {ethyl tert-butyl ether (ETBE) + (benzene, toluene, ethylbenzene, isooctane, tert-butyl alcohol, and ethanol)} over the temperature range (288.15 to 323.15) K and atmospheric pressure, have been measured over the whole concentration range. The experimental excess volumes and deviation of isentropic compressibilities data have been analysed in terms of different theoretical models. The gathered data improve open literature related to gasoline additives, and help to understand the ETBE volumetric and acoustic trend into different chemical environment.

Agronomic impacts on energy crop performance

Introduction Maize (Zea mays L.) crop with an average 65 % starch content is highly suitable for bioethanol production. Starch content of some cultivars have been slightly increased by recent plant breeding projects. The Szent Istvan University Crop Production Institute has recently started a new research on exploring the most characteristic agronomic impacts (biological bases, production sites, plant nutrition and crop year effects) influencing the efficiency of maize starch based bioethananol and so ethyl-tertiary-butyl-ether (ETBE) production. The aim of the research is to observe, identify and quantify agronomic impacts and their interactions that may have an influence on production efficiency and stability. The present paper provides information concerning the first year of the trial.

N-Alkane assimilation and tert-butyl alcohol (TBA) oxidation capacity in Mycobacterium austroafricanum strains

Mycobacterium austroafricanum IFP 2012, which grows on methyl tert-butyl ether (MTBE) and on tert-butyl alcohol (TBA), the main intermediate of MTBE degradation, also grows on a broad range of n-alkanes (C2 to C16). A single alkB gene copy, encoding a non-heme alkane monooxygenase, was partially amplified from the genome of this bacterium. Its expression was induced after growth on n-propane, n-hexane, n-hexadecane and on TBA but not after growth on LB. The capacity of other fast-growing mycobacteria to grow on n-alkanes (C1 to C16) and to degrade TBA after growth on n-alkanes was compared to that of M. austroafricanum IFP 2012. We studied M. austroafricanum IFP 2012 and IFP 2015 able to grow on MTBE, M. austroafricanum IFP 2173 able to grow on isooctane, Mycobacterium sp. IFP 2009 able to grow on ethyl tert-butyl ether (ETBE), M. vaccae JOB5 (M. austroaafricanum ATCC 29678) able to degrade MTBE and TBA and M. smegmatis mc2 155 with no known degradation capacity towards fuel oxygenates. The M. austroafricanum strains grew on a broad range of n-alkanes and three were able to degrade TBA after growth on propane, hexane and hexadecane. An alkB gene was partially amplified from the genome of all mycobacteria and a sequence comparison demonstrated a close relationship among the M. austroafricanum strains. This is the first report suggesting the involvement of an alkane hydroxylase in TBA oxidation, a key step during MTBE metabolism.

The Synthesis of Asymmetrical Tertiary Alkyl Ethers Catalyzed by Ionic Liquids with and without CO2.

The synthesis of a series of asymmetrical tertiary alkyl ethers from the etherification of tertiary alkyl alcohols with corresponding alcohols was investigated. Ionic liquids (ILs) with Brønsted acidity, [BsMIm][HSO4] (1-(4-sulfonic acid) butyl-3-methylimidazolium hydrogen sulfate) and [BMIm][HSO4] (1-butyl-3-methylimidazolium hydrogen sulfate), were found to be suitable catalysts for the reactions. Tertiary alkyl ethers including MTBE (methyl tert-butyl ether), ETBE (ethyl tert-butyl ether), IPTBE (isopropyl tert-butyl ether), TAME (tert-amyl methyl ether), and TAEE (tert-amyl ethyl ether) could be produced. Effects of reaction temperature, reaction time, and amount of the catalyst used on the synthesis of the MTBE were investigated. The conversion of TBA (tert-butyl alcohol) and the selectivity of MTBE could reach 69.9 % and 77.4 %, respectively at 393 K as the molar ratio of TBA: Methanol: [BMIm][HSO4] was 20:20:1. The reaction mixture splited into two phases after reaction, and the IL could be separated from the products simply by decantation and could be reused. CO2 could enhance the conversion of TBA and the selectivity of MTBE significantly at suitable pressures. Keywords: supercritical fluids (SCFs), methyl tert-butylether (MTBE), ethyl tert-butyl ether (IPTBE), tert-amyl methyl ether (TAME), tert-amyl ethyl ether (TAEE)

Variations in 13C/12C and D/H Enrichment Factors of Aerobic Bacterial Fuel Oxygenate Degradation

Reliable compound-specific isotope enrichment factors are needed for a quantitative assessment of in situ biodegradation in contaminated groundwater. To obtain information on the variability on carbon and hydrogen enrichment factors (epsilonC, epsilonH) the isotope fractionation of methyl tertiary (tert-) butyl ether (MTBE) and ethyl tert-butyl ether (ETBE) upon aerobic degradation was studied with different bacterial isolates. Methylibium sp. R8 showed a carbon and hydrogen isotope enrichment upon MTBE degradation of -2.4 +/- 0.1 and -42 +/- 4 per thousand, respectively, which is in the range of previous studies with pure cultures (Methylibium petroleiphilum PM1) as well as mixed consortia. In contrast, epsilonC of the beta/-proteobacterium L108 (-0.48 +/- 0.05 per thousand) and Rhodococcus ruber IFP 2001 (-0.28 +/- 0.06 per thousand) was much lower and hydrogen isotope fractionation was negligible (epsilonH < or = -0.2 per thousand). The varying isotope fractionation pattern indicates that MTBE is degraded by different mechanisms by the strains R8 and PM1 compared to L108 and IFP 2001. The carbon and hydrogen isotope fractionation of ETBE by L108 (epsilonC = -0.68 +/- 0.06 per thousand and epsilonH = -14 +/- 2 per thousand) and IFP 2001 (epsilonC = -0.8 +/- 0.1 per thousand and epsilonH = -11 +/- 4 per thousand) was very similar and seemed slightly higher than the fractionation observed upon MTBE degradation by the same strains. The low carbon and hydrogen enrichment factors observed during MTBE and ETBE degradation by L108 and IFP 2001 suggest a hydrolysis-like reaction type of the ether bond cleavage compared to oxidation of the alkyl group as suggested for the strains PM1 and R8. The variability of carbon and hydrogen enrichment factors should be taken into account when interpreting isotope pattern of fuel oxygenates with respect to biodegradation in contamination plumes.

Effects of environmental settings on MTBE removal for a mixed culture and its monoculture isolation

A mixed culture was utilized to evaluate methyl tert-butyl ether (MTBE) removal under various conditions and to isolate a MTBE-degrading pure culture. The results showed that high MTBE removal efficiencies can be reached even in the presence of other substrates. The biodegradation sequence of the target compounds by the mixed culture, in order of removal rate, was toluene, ethyl benzene, p-xylene, benzene, MTBE, ethyl ether, tert-amyl methyl ether, and ethyl tert-butyl ether. In addition, preincubation of the mixed cultures with benzene and toluene showed no negative effect on MTBE removal; on the contrary, it could even increase the degradation rate of MTBE. The kinetic behavior showed that the maximum specific growth rate and the saturation constant of the mixed culture degrading MTBE are 0.000778 h(-1) and 0.029 mg l(-1), respectively. However, a high MTBE concentration (60 mg l(-1)) was slightly inhibiting to the growth of the mixed culture. The pure culture isolated from the enrichments in the bubble-air bioreactor showed better efficiency in MTBE removal than the mixed culture; whereas, tert-butyl alcohol was formed as a metabolic intermediate during the breakdown of MTBE.

Viscosities of binary mixtures of some n-ethoxyethanols with ethyl tert-butyl ether at T = (293.15, 298.15, and 303.15) K

Viscosities at T = (293.15, 298.15, and 303.15) K in the binary mixtures of ethyl tert-butyl ether with 2-ethoxyethanol, 2-(2-ethoxyethoxy)ethanol, and 2-[2-(2-ethoxyethoxy)ethoxy]ethanol have been measured over the entire range of mixture compositions. From the experimental data, deviations in the viscosity (Δln η) and excess energies of activation for viscous flow (Δ G ∗E) have been calculated. The viscosity data were correlated with equations of Hind et al., Grunberg and Nissan, Auslaender, and McAllister. The results for Δln η and Δ G ∗E are discussed in terms of intermolecular interactions and structure of studied binary mixtures.

Ethyl tertiary-Butyl Ether: A Toxicological Review

A number of oxygenated compounds (oxygenates) are available for use in gasoline to reduce vehicle exhaust emissions, reduce the aromatic compound content, and avoid the use of organo-lead compounds, while maintaining high octane numbers. Ethyl tertiary-butyl ether (ETBE) is one such compound. The current use of ETBE in gasoline or petrol is modest but increasing, with consequently similar trends in the potential for human exposure. Inhalation is the most likely mode of exposure, with about 30% of inhaled ETBE being retained by the lungs and distributed around the body. Following cessation of exposure, the blood concentration of ETBE falls rapidly, largely as a result of its metabolism to tertiary-butyl alcohol (TBA) and acetaldehyde. TBA may be further metabolized, first to 2-methyl-1,2-propanediol and then to 2-hydroxyisobutyrate, the two dominant metabolites found in urine of volunteers and rats. The rapid oxidation of acetaldehyde suggests that its blood concentration is unlikely to rise above normal as a result of human exposure to sources of ETBE. Single-dose toxicity tests show that ETBE has low toxicity and is essentially nonirritant to eyes and skin; it did not cause sensitization in a maximization test in guinea pigs. Neurological effects have been observed only at very high exposure concentrations. There is evidence for an effect of ETBE on the kidney of rats. Increases in kidney weight were seen in both sexes, but protein droplet accumulation (with α2u-globulin involvement) and sustained increases in cell proliferation occurred only in males. In liver, centrilobular necrosis was induced in mice, but not rats, after exposure by inhalation, although this lesion was reported in some rats exposed to very high oral doses of ETBE. The proportion of liver cells engaged in S-phase DNA synthesis was increased in mice of both sexes exposed by inhalation. ETBE has no specific effects on reproduction, development, or genetic material. Carcinogenicity studies have been conducted with ETBE, TBA, and ethanol (included in this review as an endogenous precursor of acetaldehyde in the absence of TBA). A single experiment with ETBE in rats and several experiments with ethanol in rats and mice were not considered adequate for an evaluation of ETBE carcinogenicity. In male rats only, TBA induced α2u-globulin nephropathy-related renal tubule adenomas. These are generally considered to have no human relevance. In addition, increases in thyroid follicular cell adenoma incidence were associated with TBA treatment in female mice. This result lacks independent confirmation and is not supported by experiments in which similar or higher internal doses of TBA were delivered.

Use of a green and cheap ionic liquid to purify gasoline octane boosters

This work demonstrates the ability of the ionic liquid 1-ethyl-3-methylimidazolium ethylsulfate ([emim][EtSO4]) to act as an extraction solvent for liquid–liquid extraction and as an azeotrope breaker for extractive distillation, to separate the azeotropic mixture ethyl tert-butyl ether (ETBE) + ethanol, thus purifying the tertiary ether, which is the most used additive to improve the octane index of gasolines. To assess the suitability of [emim][EtSO4] to perform the mentioned separation, the liquid–liquid equilibrium (LLE) at 298.1 K and the isobaric vapour–liquid equilibrium (VLE) at 101.3 kPa have been determined for the ternary system ETBE + ethanol + [emim][EtSO4]. The separation sequence for the extractive distillation has been obtained from the residue curve map and checked by simulation. The equilibrium data have been adequately correlated by means of the NRTL equation, thus facilitating their computerized treatment.

Conceptual Design of Equilibrium Reactor−Reactive Distillation Flowsheets

Economic and environmental reasons have led to process intensifications in the process industries. Reactive distillation is the most prominent example. However, often it is a challenge to satisfy the requirement for sufficient catalyst volume for the reaction while providing the interfacial area needed for mass transfer. The combination of a reactive distillation column with a pre-reactor is a valuable alternative. This paper presents an approach to identify promising designs for such flowsheets and the optimum distribution of the reaction extent between the pre-reactor and the reactive distillation column. The methodology uses a boundary value method for the design of the column; chemical equilibrium is assumed. The column usually consists of a reactive “core”, two rectifying sections, and one stripping section. The methodology will be demonstrated for the production of ethyl-tert-butyl-ether (ETBE).

Studies on intermolecular interactions in binary mixtures of alkoxypropanols with ethyl tert -butyl ether at various temperatures

Densities and viscosities at T = 293.15, 298.15 and 303.15 K in the binary liquid mixtures of ethyl tert-butyl ether (ETBE) with propylene glycol monomethyl ether (PM), dipropylene glycol monomethyl ether (DPM) and tripropylene glycol monomethyl ether (TPM) have been measured over the entire mixture compositions. These data have been used to compute the excess molar volumes (V E), the excess energies of activation for viscous flow ΔG* E, the deviations in the viscosity (Δη) from a mole fraction average and the Grunberg–Nissan interaction parameters (d 12). The values of V E, Δη, ΔG* E and d 12 are negative over the entire range of composition for all the studied binary mixtures. The changes of V E, Δη, ΔG* E and d 12 with variations in the composition and the chain-length of the alkyl groups in the alkoxypropanol molecules are discussed in terms of the intermolecular interactions.

Control System Design for a Single Feed ETBE Reactive Distillation Column

Reactive distillation (RD) is advantageous for the Ethyl Tert-Butyl Ether (ETBE) synthesis. The steady state model of an ETBE reactive distillation column created using the simulator HYSYS is analyzed to synthesize effective control structures. Since the column exhibits input multiplicity with the dual process objectives of ETBE RD (isobutene conversion and ETBE purity), inferential variables are selected. A control structure that organizes a sensitive tray temperature in the stripping section using the reboiler duty and maintains the temperature difference of reactive trays using the reflux flow, is found to be most suitable. A decentralized PI controller and constrained Model Predictive Controller (MPC) are implemented, and performances are compared for set point tracking and disturbance rejection. MPC control algorithms are implemented in MATLAB and interfaced with HYSYS. Constrained MPC (CMPC) is found to be effective for load disturbance rejection, which frequently occurs in the single feed configuration.

Experimental and modelling study of gasoline surrogate mixtures oxidation in jet stirred reactor and shock tube

The oxidation of several mixtures of surrogate for gasoline was studied using a jet stirred reactor and a shock tube. One representative of each classes constituting gasoline was selected: iso-octane, toluene, 1-hexene and ethyl tert-butyl ether (ETBE). The experiments were carried out in the 800–1880 K temperature range, for two different initial pressures (0.2 and 1 MPa), with an initial fuel molar fraction of 0.001. The equivalence ratio varied from 0.5 to 1.5. Each hydrocarbon sub-mechanism was validated using shock tube data. The full mechanism describing the surrogate fuel oxidation is constituted of the sub-mechanisms for each fuel components and by adding interaction reactions between different hydrocarbon fragments. Good agreement between the experimental results and the computations was observed under JSR and shock tube conditions.

Kinetics of gas phase synthesis of ethyl- tert-butyl ether (ETBE) on Wells–Dawson catalyst

Mechanism and kinetics of gas phase synthesis of ethyl- tert-butyl ether (ETBE) over Wells–Dawson heteropolyacid H 6P 2W 18O 62 in an anhydrous system have been discussed. The rates of ETBE synthesis were measured in a differential reactor for ethanol–isobutene system, far from the limitation by chemical equilibrium. In the pressure range studied, kinetic measurements show that isobutene has an enhancing effect on the reaction while ethanol has an inhibitory one. Catalytic and sorption experiments allowed to formulate the mechanism of ETBE synthesis which assumed isobutene adsorption and oligomerization at the surface of heteropolyacid crystallites and the formation of carbocation using protons supplied from the bulk of catalyst. Kinetic equations were deduced indicating that it is the concentration of protons forming inter-anionic bonds between heteropolyacid anions which determines the catalytic activity of heteropolyacid.

Simultaneous determination of methyl tert-butyl ether, its degradation products and other gasoline additives in soil samples by closed-system purge-and-trap gas chromatography–mass spectrometry

A new protocol for the simultaneous determination of methyl tert-butyl ether (MTBE); its main degradation products: tert-butyl alcohol (TBA) and tert-butyl formate (TBF); other gasoline additives, oxygenate dialkyl ethers: ethyl tert-butyl ether (ETBE), tert-amyl methyl ether (TAME) and diisopropyl ether (DIPE); aromatics: benzene, toluene, ethylbenzene and xylenes (BTEX) and other compounds causing odour events such as dicyclopentadiene (DCPD) and trichloroethylene (TCE) in soils has been developed. On the basis of US Environmental Protection Agency (EPA) method 5035A, a fully automated closed-system purge-and-trap coupled to gas chromatography/mass spectrometry (P&T-GC/MS) was optimised and permitted to detect μg/kg concentrations in solid matrices avoiding losses of volatile compounds during operation processes. Parameters optimised were the sampling procedure, sample preservation and storage, purging temperature, matrix effects and quantification mode. Using 5 g of sample, detection limits were between 0.02 and 1.63 μg/kg and acceptable method precision and accuracy was obtained provided quantification was performed using adequate internal standards. Soil samples should be analysed as soon as possible after collection, stored under −15 °C for not longer than 7 days if degradation products have to be analysed. The non-preservative alternative (empty vial) provided good recoveries of the most analytes when freezing the samples up to 7 day holding time, however, if biologically active soil are analysed the preservation with trisodium phosphate dodecahydrate (Na 3PO 4·12H 2O or TSP) is strongly recommended more than sodium bisulphate (NaHSO 4). The method was finally applied to provide threshold and background levels of several gasoline additives in a point source and in sites not influenced by gasoline spills. The proposed method provides the directions for the future application on real samples in current monitoring programs at gasoline pollution risk sites where till now little monitoring data for MTBE in soils are available.

Determination of low level methyl tert-butyl ether, ethyl tert-butyl ether and methyl tert-amyl ether in human urine by HS-SPME gas chromatography/mass spectrometry

Methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE) and tert-amyl methyl ether (TAME) are oxygenated compounds added to gasoline to enhance octane rating and to improve combustion. They may be found as pollutants of living and working environments. In this work a robotized method for the quantification of low level MTBE, ETBE and TAME in human urine was developed and validated. The analytes were sampled in the headspace of urine by SPME in the presence of MTBE-d12 as internal standard. Different fibers were compared for their linearity and extraction efficiency: carboxen/polydimethylsiloxane, polydimethylsiloxane/divinylbenzene, and polydimethylsiloxane. The first, although highly efficient, was discarded due to deviation of linearity for competitive displacement, and the polydimethylsiloxane/divinylbenzene fiber was chosen instead. The analysis was performed by GC/MS operating in the electron impact mode. The method is very specific, with range of linearity 30–4600 ng L −1, within- and between-run precision, as coefficient of variation, <22 and <16%, accuracy within 20% the theoretical level, and limit of detection of 6 ng L −1 for all the analytes. The influence of the matrix on the quantification of these ethers was evaluated analysing the specimens of seven traffic policemen exposed to autovehicular emissions: using the calibration curve and the method of standard additions comparable levels of MTBE (68–528 ng L −1), ETBE (<6 ng L −1), and TAME (<6 ng L −1) were obtained.

The thermodynamics of vaporization of ethyl tert-butyl ether, isobutyl tert-butyl ether, and di-isopropyl ether

The boiling temperatures of ethyl tert-butyl ether (ETBE), isobutyl tert-butyl ether (IBTBE), and di-isopropyl ether (DIPE) have been measured by comparative ebulliometry over the moderate pressure range 10.8 ⩽ ( P/kPa) ⩽ 101.7. The equations of the temperature dependences of the saturated vapour pressures and enthalpies of vaporization have been derived. The normal boiling temperatures of the ethers were computed to be 345.84 K, 386.06 K, and 341.64 K, respectively. The experimental data on the vapour pressure of the ethers under study were extended to the whole range of the liquid phases between critical and triple points by means of corresponding states law and combined treatment of the pT-parameters and low-temperature differences of the heat capacities of ideal gas and liquid, Δ C p = C p ∘ ( g ) - C p ∘ ( l ) , respectively.

Enzymes and genes involved in the aerobic biodegradation of methyl tert-butyl ether (MTBE)

Fuel oxygenates, mainly methyl tert-butyl ether (MTBE) but also ethyl tert-butyl ether (ETBE), are added to gasoline in replacement of lead tetraethyl to enhance its octane index. Their addition also improves the combustion efficiency and therefore decreases the emission of pollutants (CO and hydrocarbons). On the other hand, MTBE, being highly soluble in water and recalcitrant to biodegradation, is a major pollutant of water in aquifers contaminated by MTBE-supplemented gasoline during accidental release. MTBE was shown to be degraded through cometabolic oxidation or to be used as a carbon and energy source by a few microorganisms. We have summarized the present state of knowledge about the microorganisms involved in MTBE degradation and the MTBE catabolic pathways. The role of the different enzymes is discussed as well as the rare and recent data concerning the genes encoding the enzymes involved in the MTBE pathway. The phylogeny of the microorganisms isolated for their capacity to grow on MTBE is also described.

Multiplicity Analysis in Reactive Distillation Column Using ASPEN PLUS

Reactive distillation processes for synthesis of ethylene glycol (EG) and ethyl tert-butyl ether (ETBE) were modeled with the simulation package ASPEN PLUS. The input multiplicity and output multiplicity were discussed with the method of sensitivity analysis for both cases. In EG production process, steady state multiplicities were studied in terms of effective liquid holdup volume and boil-up ratio. In ETBE synthesis process, the user kinetic subroutine was supplied into ASPEN PLUS firstly, and then the composition, temperature and reaction-rate profiles within the reactive distillation column were presented in detail. A set of stable solution branches based on distinct initial guesses for a range of boil-up ratio were found in EG synthesis. Input multiplicities were observed for a range of reboiler duty at several values of reflux ratio for ETBE synthesis process. These results can be used to avoid excessive energy consumption and achieve optimum design of reactive distillation column.