Tert-amyl Ether Research Articles

Liquid–liquid equilibrium for ternary methyl tert-amyl ether + phenol + water system at 283.15, 298.15, and 313.15 K

ABSTRACT Liquid–liquid equilibrium data have been measured for the ternary MTAE + phenol + water system at 283.15, 298.15, and 313.15 K. Experimental results show that the temperature increase leads to a decrease in phenol distribution coefficient. At a temperature of 298.15 K, the maximum achieved value of distribution coefficient is 46.5. The NRTL model was applied to correlate the experimental data. The obtained experimental data were compared with the literature data for the same ternary systems with the use of methyl isobutyl ketone, butyl acetate, and methyl tert-butyl ether as extractants.

ПЕРЕПРОФИЛИРОВАНИЕ УСТАНОВКИ ПРОИЗВОДСТВА МЕТИЛ-ТРЕТ-БУТИЛОВОГО ЭФИРА НА ПОЛУЧЕНИЕ НОВОЙ ПРОДУКЦИИ

The possibility of converting the existing plant for the production of methyl tert-butyl ether to the production of oxygenates of another type, for example, methyl tert-amyl ether, was considered

Single Photon Ionization/Photoelectron Ionization-Membrane Introduction Mass Spectrometry for On-line Analysis Ethers Gasoline Additive in Water

A magnetic field enhanced photoelectron ionization (MEPEI) source combined with single photon ionization (SPI) for membrane inlet time-of-flight mass spectrometry was used for on-line detection of ether gasoline additive. Methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), methyl tert-amyl ether (TAME) and isopropyl ether (DIPE) were selected as the typical pollutants. A membrane inlet was used to transfer the analytes from liquid into gas phase in an on-line manner by pervaporization without sample pretreatment. Less sample fragments were in SPI, and molecular ions could be used to quick preliminarily qualitative analysis; high energy electrons and fragmentations produced by MEPEI can be used to accurate qualitative isomers and overcame the problem of resolution of overlapping peaks in complex matrix when using direct injection. Under the optimal conditions such as membrane temperature 60 degrees C, membrane thicknesses 50 mu m and membrane areas 160 cm(2), the single sample analysis time was less than 100 s, and the limits of detection for MTBE, ETBE, TAME and DIPE were 5.5, 4.8, 3.3 and 4.3 mu g/L, respectively. The instrument has been successfully applied to rapid analysis of MTBE in simulated water by gasoline.

Oxidative degradation of alternative gasoline oxygenates in aqueous solution by ultrasonic irradiation: Mechanistic study

Widespread pollution has been associated with gasoline oxygenates of branched ethers methyl tert-butyl ether (MTBE), di-isopropyl ether (DIPE), ethyl tert-butyl ether (ETBE), and tert-amyl ether (TAME) which enter groundwater. The contaminated plume develops rapidly and treatment for the removal/destruction of these ethers is difficult when using conventional methods. Degradation of MTBE, with biological methods and advanced oxidation processes, are rather well known; however, fewer studies have been reported for degradation of alternative oxygenates. Degradation of alternative gasoline oxygenates (DIPE, ETBE, and TAME) by ultrasonic irradiation in aqueous oxygen saturation was investigated to elucidate degradation pathways. Detailed degradation mechanisms are proposed for each gasoline oxygenate. The common major degradation pathways are proposed to involve abstraction of α-hydrogen atoms by hydroxyl radicals generated during ultrasound cavitation and low temperature pyrolytic degradation of ETBE and TAME. Even some of the products from β-H abstraction overlap with those from high temperature pyrolysis, the effect of β-H abstraction was not shown clearly from product study because of possible 1,5 H-transfer inside cavitating bubbles. Formation of hydrogen peroxide and organic peroxides was also determined during sonolysis. These data provide a better understanding of the degradation pathways of gasoline oxygenates by sonolysis in aqueous solutions. The approach may also serve as a model for others interested in the details of sonolysis.

Liquid–liquid equilibria for ternary mixtures of methyl tert-amyl ether + methanol (or ethanol) + imidazolium-based ionic liquids at 298.15 K

Liquid–liquid equilibria (LLE) were determined for ternary systems {methyl tert-amyl ether (TAME)+methanol+1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4])}, {TAME+ethanol+[Bmim][BF4]}, {TAME+methanol+1-ethyl-3-methylimidazolium ethylsulfate (EMISE)} and {TAME+ethanol+EMISE} at 298.15K. Experiments were carried out at atmospheric pressure using stirred and thermo-regulated cells. The experimental data were correlated with the well-known non random two liquid (NRTL) and universal quasi chemical (UNIQUAC) activity coefficient models. In addition, the distribution coefficients and the selectivities of the ionic liquids of [Bmim][BF4] and EMISE for methanol and ethanol in the TAME phase were measured.

Odour and flavour thresholds of gasoline additives (MTBE, ETBE and TAME) and their occurrence in Dutch drinking water collection areas

The use of ETBE (ethyl- tert-butylether) as gasoline additive has recently grown rapidly. Contamination of aquatic systems is well documented for MTBE (methyl- tert-butylether), but less for other gasoline additives. Due to their mobility they may easily reach drinking water collection areas. Odour and flavour thresholds of MTBE are known to be low, but for ETBE and TAME (methyl- tert-amylether) hardly information is available. The objective here is to determine these thresholds for MTBE, ETBE and TAME, and relate these to concentrations monitored in thousands of samples from Dutch drinking water collection areas. For ETBE odour and flavour thresholds are low with 1–2 μg L −1, for MTBE and TAME they range from 7 to 16 μg L −1. In most groundwater collection areas MTBE concentrations are below 0.1 μg L −1. In phreatic groundwaters in sandy soils not covered by a protective soil layer, occasionally MTBE occurs at higher concentrations. For surface water collection areas a minority of the locations is free of MTBE. For river bank and dune infiltrates, at a few locations the odour and flavour threshold is exceeded. For ETBE fewer monitoring data are available. ETBE was found in 2 out of 37 groundwater collection areas, in concentrations below 1 μg L −1. In the surface water collection areas monitored ETBE was found in concentrations near to the odour and flavour thresholds. The low odour and flavour thresholds combined with the high mobility and persistence of these compounds, their high production volumes and their increased use may yield problems with future production of drinking water.

Single-walled carbon nanotubes as an effective adsorbent in solid-phase microextraction of low level methyl tert-butyl ether, ethyl tert-butyl ether and methyl tert-amyl ether from human urine

Carbon nanotubes (CNTs) are a kind of new carbon-based nano-materials which have drawn great attention in many application fields. The potential single-walled carbon nanotubes (SWCNTs) as solid-phase microextraction (SPME) adsorbents for the preconcentration of environmental pollutants have been investigated in recent years. The goal of this work was to investigate the feasibility of SWCNTs used as adsorbents for solid-phase microextraction of methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE) and tert-amyl methyl ether (TAME) in human urine. SWCNTs were attached onto a stainless steel wire through organic binder. Potential factors affecting the extraction efficiency were optimized, including extraction time, extraction temperature, desorption time, desorption temperature, and salinity. The developed method showed good performance according to the ICH performance criteria for bioanalytical methods. The calibration curves of the ethers were linear (r2≥0.992) in the range from 10 to 5000ngL−1. The limits of detection at a signal-to-noise (S/N) ratio of 3 were 10ngL−1 for all the analytes. In addition, compared with the commercial carboxen/polydimethylsiloxane (CAR/PDMS) fiber, the SWCNT fiber showed better thermal stability (over 350°C) and longer life span (over 150 times). The developed method was applied successfully to determine trace level of the ethers in urine of 10 healthy male volunteers.

Binary Liquid−Liquid Equilibrium (LLE) for Methyl tert-Amyl Ether (TAME) + Water from (288.15 to 313.15) K and Ternary LLE for Systems of TAME + C1−C4 Alcohols + Water at 298.15 K

The binary liquid−liquid equilibrium data for the system methyl tert-amyl ether + water from (288.15 to 313.15) K and the ternary liquid−liquid equilibria for the systems methyl tert-amyl ether + C1−C4 alcohols (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and 2-butanol) + water at 298.15 K were analytically determined at atmospheric pressure by the use of stirred and thermo-regulated cells. The experimental binary and ternary liquid−liquid equilibrium data were correlated with the NRTL and UNIQUAC activity coefficient models. Bachman−Brown, Hand, and Othmer−Tobias correlations were used to ascertain the reliability of the experimental data for each system. In addition, the distribution and selectivity of C1−C4 alcohols as solvents were analyzed.

Specific consumption of liquid biofuels in gasoline fuelled engines

Oxygenated fuels increase fuel consumption due to their low enthalpy of combustion; however, their high antiknock index renders them suitable for use in engines with a high compression rate, increasing their thermal yield. This study evaluated the performance of biorenewable oxygenated fuels (ethanol and isoamyl alcohol) and partially renewable fuels (ETBE: ethyl tert-butyl ether, TAEE: tert-amyl ethyl ether and di-TAE: di- tert-amyl ether) with high degree of purity and in mixtures with automotive gasoline, based on tests with Otto cycle engines. Among the oxygenated fuels evaluated here, di-TAE was found to present the best characteristics of performance, both individually and in mixtures with gasoline.

Thermodynamics of oxygenate fuel additives as a function of temperature

This article reports experimental data of density and ultrasonic velocity at the range from 278.15 to 323.15 K and atmospheric pressure of ethers used as additives in fuels (methyl tert-butyl ether ethyl tert-butyl ether, tert-amyl ether and diisopropyl ether). From the experimental data, temperature dependent polynomials were fitted and theoretical models were used to correlate these properties. The MTC Lattice Gas EOS is used to correlate simultaneously vapour pressures and volumetric properties. Free Length Theory is applied to estimate the ultrasonic velocity of the chemicals as a function of temperature, satisfactory predictions were obtained. The dependence of temperature showed by these magnitudes reveals a strong interaction at low values.

Study of fuel oxygenates solubility in aqueous media as a function of temperature and tert-butyl alcohol concentration

Methyl tert-butyl ether (MTBE) is the most widely used oxygenate in gasoline blending and has become one of the world’s most widespread groundwater and surface water pollutants. Alternative oxygenates to MTBE, namely ethyl tert-butyl ether (ETBE), tert-amyl ether (TAME) and diisopropyl ether (DIPE) have been hardly studied yet. The solubility of these chemicals is a key thermodynamic information for the assessment of the fate and transport of these pollutants. This work reports experimental data of water solubility at the range from 278.15 to 313.15K and atmospheric pressure of ethers used in fuels (MTBE, ETBE, TAME and DIPE) due to the strong influence of temperature on its trend. From the experimental data, temperature dependent polynomials were fitted, thermodynamic parameters were calculated and theoretical models were used for prediction. Finally, the tert-butyl alcohol (TBA) influence in the solubility of MTBE and ETBE in aqueous media was studied.

Comprehensive Experimental and Theoretical Study of Chemical Equilibria in the Reacting System of thetert-Amyl Methyl Ether Synthesis

The chemical equilibrium of the reactive system (methanol+isoamylenes<-->methyl tert-amyl ether) was studied in the temperature range 298-393 K in the liquid phase using the method of sealed ampoules as well as in the gaseous phase using a tubular flow reactor in the temperature range 355-378 K. In both cases, a cation exchanger Amberlist-15 was used as a heterogeneous catalyst. The reactive system of the methyl tert-amyl ether synthesis exhibits a strong nonideal behavior of the mixture compounds in the liquid phase. The knowledge of the activity coefficients is required in order to obtain the thermodynamic equilibrium constants Ka. Two well-established procedures, UNIFAC and COSMO-RS, have been used to assess activity coefficients of the reaction participants in the liquid phase. Thermodynamic equilibrium constants KP measured in the gaseous phase together with the vapor pressures of the pure compounds have been used to obtain Ka in the liquid phase on a consistent experimental basis in order to check the results obtained from the UNIFAC and COSMO-RS methods. Enthalpies of reactions DeltarH degrees of the methyl tert-amyl ether synthesis reaction in the gaseous and in the liquid phase were obtained from temperature dependences of the corresponding thermodynamic equilibrium constants. Consistency of the experimental data of DeltarH degrees was verified with help of enthalpies of formation and enthalpies of vaporization of methyl tert-amyl ether, methanol, and methyl-butenes, available from the literature. For the sake of comparison, high-level ab initio calculations of the reaction participants have been performed using the Gaussian-03 program package. Absolute electronic energy values, normal frequencies (harmonic approximation), and moments of inertia of the molecules have been obtained using G2(MP2), G3(MP2), and G3 levels. Using these results, calculated equilibrium constants and the enthalpy of reaction of the methyl tert-amyl ether synthesis in the gaseous phase based on the principles of statistical thermodynamics are found to be in acceptable agreement with the data obtained from the thermochemical measurements.

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.

Análisis de riesgo a la salud de una instalación petrolera del Suroeste de México

Dur ing an En vi ron men tal Au dit in an oil stor age and dis tri bu tion sta tion (TAD) lo cated at South-west Mex ico, hy dro car bon con tam i na tion was de tected. Be cause of it, a com plete study of the site’s con tam i na tion was re quired. From this work’s re sults, it can be stated that TAD sub soil is con tam i nated by to tal pe tro leum hy dro car bons (TPH), in con cen tra tions from ND to 59,000 mg/kg. Nei ther ben zene, to lu ene, ethylbenzene or xylenes (BTEX), nor methyl tert-butyl ether (MTBE), nor methyl tert-amyl ether (MTE) were de tected. From the 16 polycyclic ar o matic hy dro car bons (PAH) an a lyzed, only naph tha lene was found in one sam ple point at a con cen tra tion be low 1 mg/kg. The pres ence of Fe, Pb, and Zn was iden ti fied in the sub soil, but the cal cu lated geo-accumulation in dexes sug gest a nat u ral con cen tra tions and not a con tam i na tion’s prod uct. TPH were found in groundwaters, but only in one of the six sam pled wells over the rec om mended level of 10 mg/l. It was also found that Fe con cen tra tions ex ceed the sug gested value of 0.3 mg/l in five of the six sam pled wells. It was de ter mined that ground wa ter’s pH value is not linked to the

Methyl tert-Amyl Ether Synthesis Catalyzed by a Sulfonic Cation Exchanger: The Effect of the Degree of Hydration of the Cation Exchanger on the Catalytic Activity and Reaction Mechanism

The catalytic properties of the fibrous sulfonic acid cation exchanger FIBAN K-1 in methyl tert-amyl ether synthesis are studied as a function of its water content. Reducing the degree of hydration of the cation exchanger to <2 H2O molecules per SO3H group diminishes the proportion of the desired product in the catalysate. According to 13C NMR data, protonation of methylbutenes in the air-dry cation exchanger phase (which contains 4 H2O molecules per SO3H group) involves [nH2O] ⋅ H+ species and is accompanied by olefin hydration and the formation of protonated tert-amyl alcohol.

Thermochemistry of Branched Ethers: Experimental Study of Chemical Equilibrium in the Reacting System of tert-Amyl Alkyl Ether Synthesis

The chemical equilibrium of the reactive systems (alkanol + methylbutenes ⇔ alkyl tert-amyl ether) with the following alkyl substituents: ethyl, propyl, butyl, iso-propyl, sec-butyl, and cyclohexyl, were studied in the liquid phase. Reactions were investigated in the screwed vials in the temperature range (298 to 393) K, and a cation exchanger Amberlist 15 was used as heterogeneous catalyst. Enthalpies of reactions of tert-amyl alkyl ethers synthesis in the liquid phase were obtained from the temperature dependence of the equilibrium constants and used to derive standard enthalpies of formation, , of tert-amyl alkyl ethers. For the sake of comparison, these enthalpies of formation have been calculated using improved Benson's increments. Calculated values are in close agreement with those from thermochemical measurements.

Kinetics research for the synthesis of branch ether using genetic-simulated annealing algorithm with multi-pattern evolution

To obtain the kinetics parameters for the complex reaction system, a more intellectualized hybrid evolutionary algorithm was developed. In this new method, the normal genetic algorithm (GA) was modified with adaptive multi-annealing crossover and mutation strategies instead of simple strategy. The multi-pattern evolution was also adapted to improve the search efficiency. This hybrid algorithm not only avoids the problem of local optimum, but shows a higher estimating precision and a better convergence than that the normal GA. By using this algorithm, the kinetics parameters for the synthesis of ethyl tert-amyl ether from ethanol and tert-amyl alcohol over strongly acidic cation exchange resin (Ambelyst 15 (A-15)) as catalyst were successfully estimated. The calculated results using the parameters obtained from the hybrid evolutionary algorithm agree well with the experimental data.

Anaerobic biotransformation of fuel oxygenates under sulfate-reducing conditions

The anaerobic biotransformation of methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), and methyl tert-amyl ether (TAME) was evaluated under different anoxic electron-accepting conditions. Enrichments were established with a polluted estuarine sediment inoculum under conditions promoting denitrification, sulfate reduction, Fe(III) reduction, or methanogenesis. Complete loss of MTBE and TAME was observed under sulfate-reducing conditions, concomitant with the reduction of sulfate. A stoichiometric amount of tert-butyl alcohol and tert-amyl alcohol accumulated indicating that O-demethylation was the initial step in MTBE and TAME biodegradation under sulfate-reducing conditions. No transformation of MTBE or TAME was observed under the other electron-accepting conditions over 3 years. Under all conditions tested, there was no biotic loss of ETBE observed. MTBE and TAME were depleted upon refeeding the sulfate-reducing cultures. This study definitely demonstrates the anaerobic biodegradability of MTBE and TAME under sulfate-reducing conditions.

Anaerobic biotransformation of fuel oxygenates under sulfate-reducing conditions

The anaerobic biotransformation of methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), and methyl tert-amyl ether (TAME) was evaluated under different anoxic electron-accepting conditions. Enrichments were established with a polluted estuarine sediment inoculum under conditions promoting denitrification, sulfate reduction, Fe(III) reduction, or methanogenesis. Complete loss of MTBE and TAME was observed under sulfate-reducing conditions, concomitant with the reduction of sulfate. A stoichiometric amount of tert-butyl alcohol and tert-amyl alcohol accumulated indicating that O-demethylation was the initial step in MTBE and TAME biodegradation under sulfate-reducing conditions. No transformation of MTBE or TAME was observed under the other electron-accepting conditions over 3 years. Under all conditions tested, there was no biotic loss of ETBE observed. MTBE and TAME were depleted upon refeeding the sulfate-reducing cultures. This study definitely demonstrates the anaerobic biodegradability of MTBE and TAME under sulfate-reducing conditions.

Exposure to Gasoline Vapour during Offloading of Tankers and Railway Wagons and Biological Multicomponent Monitoring

The purpose of this study was to measure the exposure of oil depot workers to gasoline vapour components during the offloading of tankers and railway wagons. We also compared the concentrations of airborne benzene, toluene and oxygenates with urinary concentrations of these components or their metabolites at the end of the shift and before the next shift as a means of assessing exposure during work shift. The workers in the offloading operations were chosen for the study because their exposure was expected to be relatively high, and there was no previous literature on the biological monitoring of coincident gasoline components in urine samples from these groups. In this study, all gasoline was unleaded, and either methyl tert-butyl ether (MTBE) alone or together with methyl tert-amyl ether (MTAE) were used as oxygenates to enhance the octane number and to ensure cleaner exhaust gases. The maximum oxygenate content varied from 12% in reformulated gasoline types to 15% in oxygenated types. In reformulated gasoline the content of aromatic hydrocarbons is also regulated to less than 30% and that of benzene to less than 1%. Several studies on road tanker drivers have described the exposure to gasoline vapour components 1‐3) , and the correlation between air and urine concentrations of gasoline components has been determined for post-shift and prenext-shift samples of MTBE under field conditions 2, 3) .