Methyl Tert Research Articles

Increasing Raffinate Dewaxing Efficiency

The efficiency of dewaxing of wide and narrow distillation raffinates using different mixed solvents: acetone and methyl–tert–butyl ether (MTBE), acetone and toluene, methyl ethyl ketone (MEK) and toluene, is compared. Decreasing the cutpoints from 100–140 to 50–70°C increases the filtration rate by 2 and more times and the yield of dewaxed lube oil by 2.5–5% as a function of the solvent used.

Emission of alcohols and carbonyl compounds from a spark ignition engine. Influence of fuel and air/fuel equivalence ratio.

A spark ignition engine was used to study the impact of fuel composition and of the air/fuel equivalence (lambda) ratio on exhaust emissions of alcohols and aldehydes/ketones. Fuel blends contained eight hydrocarbons (n-hexane, 1-hexene, cyclohexane, n-octane, isooctane, toluene, o-xylene, and ethylbenzene (ETB)) and four oxygenated compounds (methanol, ethanol, 2-propanol, and methyl tert butyl ether (MTBE)). Exhaust methanol is principally produced from fuel methanol and MTBE but also from ethanol, 2-propanol, isooctane, and hexane. Exhaust ethanol and 2-propanol are produced only from the respective fuel compounds. Exhaust formaldehyde is mainly produced from fuel methanol, acetaldehyde from fuel ethanol, and propionaldehyde from straight-chain hydrocarbons. Exhaust acroleine comes from fuel 1-hexene, acetone from 2-propanol, n-hexane, n-octane, isooctane, and MTBE. Exhaust crotonaldehyde comes from fuel 1-hexene, cyclohexane, n-hexane, and n-octane, methacroleine from fuel isooctane, and benzaldehyde from fuel aromatics. Light pollutants (C1-C2) are most likely formed from intermediate species which are quite independent of the fuel composition. An increase in A increases the exhaust concentration of acroleine, crotonaldehyde, methacroleine, and decreases these of the three alcohols for the alcohol-blended fuels. The concentration of methanol, formaldehyde, propionaldehyde, and benzaldehyde is a maximum atstoichiometry. The exhaust concentration of acetaldehyde and acetone presents a complex behavior: it increases in some cases, decreases in others, or presents a maximum at stoichiometry. The concentration of four aldehydes (formaldehyde, acetaldehyde, propionaldehyde, and benzaldehyde) is also linked with the exhaust temperature and fuel H/C ratio.

Estimation of Methyl tert -Butyl Ether Plume Length Using the Domenico Analytical Model

Methyl tert -butyl ether (MTBE) plume is controlled by many factors, primarily by groundwater flow velocity, dispersion, natural attenuation. This study employed an analytical model introduced by 3, J. Hydrol. 91, 49–58.) to describe the MTBE concentration distribution horizontal pattern and estimated the MTBE plume length. The model was applied to 90 leaking underground storage tank cases in Los Angeles, CA, U.S.A. The analytical model was calibrated with field data for each case using a Microsoft Excel spreadsheet program. Methyl tert -butyl ether concentrations in one source monitoring well and one to two downgradient centerline monitoring wells were used for each case study. When the centerline well is not available, the closest off-centerline wells were projected to the centerline using an ellipse trigonometry method. The model parameter values for longitudinal dispersivity, groundwater velocity, and degradation rate constant were calibrated using the field data and then used to estimate the maximum distance between source well and the plume edge. This study demonstrates that the Domenico model can be applied to MTBE plume investigation when adequate field data are available. The correlation coefficients calculated based on the results of the 90 case studies indicate that MTBE plume length has a poor correlation with MTBE concentration at the source well, and a moderate negative correlation with the degradation rate constant (−0.65) and λ/ν ratio (0.64). Furthermore, MTBE plume length has a poor correlation with the longitudinal dispersivity (−0.4), hydraulic gradient (−0.1), and groundwater velocity (0.17).

Estimation of Methyl tert -Butyl Ether Plume Length Using the Domenico Analytical Model

Methyl tert -butyl ether (MTBE) plume is controlled by many factors, primarily by groundwater flow velocity, dispersion, natural attenuation. This study employed an analytical model introduced by Domemico (1987, J. Hydrol 91 , 49-58.) to describe the MTBE concentration distribution horizontal pattern and estimated the MTBE plume length. The model was applied to 90 leaking underground storage tank cases in Los Angeles, CA, U.S.A. The analytical model was calibrated with field data for each ease using a Microsoft Excel spreadsheet program. Methyl tert -butyl ether concentrations in one source monitoring well and one to two downgradient centerline monitoring wells were used for each case study. When the centerline well is not available, the closest off-centerline wells were projected to the centerline using an ellipse trigonometry method. The model parameter values for longitudinal dispersivity, groundwater velocity, and degradation rate constant were calibrated using the field data and then used to estimate the maximum distance between source well and the plume edge. This study demonstrates that the Domenico model can be applied to MTBE plume investigation when adequate field data are available. The correlation coefficients calculated based on the results of the 90 case studies indicate that MTBE plume length has a poor correlation with MTBE concentration at the source well, and a moderate negative correlation with the degradation rate constant ( m 0.65) and u / v ratio (0.64). Furthermore, MTBE plume length has a poor correlation with the longitudinal dispersivity ( m 0.4), hydraulic gradient ( m 0.1), and groundwater velocity (0.17).

Production of Environmentally Clean High—Octane Gasoline Additives

Acceptance tests were successfully conducted and the unit for production of a high—octane, environmentally clean gasoline additive — methyl tert—butyl ether (MTBE) — with output of 60,000 tons/year in feedstock — the C4 catalytic cut — was started up on March 17, 2002 at UKRTATNAFTA OJSC (Kremenchug). The unit was designed by Ukrneftekhimproekt OJSC (Kiev) based on Neftekhimstart Ltd. technology (Yaroslavl') and “turnkey” constructed by Kedr—89 Ltd.

BOOST FOR ETHANOL

IF CALIFORNIA BANS A GASOLINE additive that is contaminating water supplies, it will have to switch to ethanol, the Environmental Protection Agency ruled last week. California officials predict higher gasoline prices for the Golden State because of the decision and may challenge EPA in court. Meanwhile, midwestern corn-growing interests are cheering at the prospect of supplying corn-derived ethanol for California's big urban gasoline market. Since 1990, the Clean Air Act has required that reformulated gasoline, sold in heavily polluted urban areas, contain 2% oxygen by weight to help reduce smog-related emissions. Throughout much of the U.S., refiners add methyl tert -butyl ether (MTBE) to boost the oxygen content of this cleaner burning fuel. MTBE is increasingly found in drinking water. So to protect water supplies, California Gov. Gray Davis (D) ordered a phaseout of MTBE in gasoline sold in the state by 2003. Because refiners say they now can make cleaner burning gasoline without adding oxygenates, Da...

Accurate Chemical Analysis of MTBE in Environmental MediaTechnical Note

The new millennium ushers in changes for refiners of automobile gasoline in the United States, as well as for the state and federal regulators who establish guidelines for gasoline formulation and environmental regulation governing the fate of gasoline-related chemicals in the nation's air, soil and groundwater. One current issue in the gasoline formulation debate centers on the comparison of the proven benefits of the addition of chemical oxygenates--especially methyl tert -butyl ether (MTBE)--to gasoline (to improve tailpipe emission quality) against the presumed environmental problems caused by the presence of oxygenates in ground- and surface waters due to fugitive releases of gasoline. Credible debate on this subject presumes that current and past environmental monitoring data for MTBE in environmental samples is accurate and precise. Experience suggests that this assumption is not correct, in part because certain analytical methodologies--particularly older methods supported by the U.S. Environmental Protection Agency--can fall short of reasonable data quality goals for measurement of MTBE. This Technical Note summarizes the standard EPA methods available to site investigators who need to measure MTBE in environmental media, the limitations and advantages of these measurement techniques, and recommendations for improving these standard EPA methods to yield the highest quality MTBE environmental residue data.

MTBE in California Drinking Water: An Analysis of Patterns and Trends

Over the past decade, there has been much publicity surrounding the impact of Methyl tert -butyl ether (MTBE) on drinking water supplies in the United States. In California, the presence of MTBE in groundwater and drinking water has led to a ban on the future use of MTBE in gasoline. Other states, such as those in the northeast, are also seeking ways to reduce or eliminate the use of MTBE due to perceived threats to the environment and public health. Despite claims about the incidence of MTBE in drinking water, no comprehensive characterization has been conducted on the available drinking water monitoring data. This paper provides a detailed analysis of the MTBE drinking water data compiled by the California Department of Health Services (CDHS) from 1995 to 2000. We find that MTBE was detected in about 1.3% of all drinking water samples, 2.5% of drinking water sources, and 3.7% of drinking water systems in California over this 6-year period. Our analysis reveals that many drinking water sources are not sampled routinely for MTBE, and in those sources that appear to be affected by MTBE, the compound is not consistently detected. The majority of MTBE detections are also concentrated in several geographic areas, which contain about 9–21% of the total California population. Average detected MTBE concentrations have decreased significantly since 1995 and 1996, ranging from 5 to 15ppb over the last 3 years depending on the outcome of interest. Of the samples in which MTBE was present above the analytical detection limit, the concentrations in approximately 73% of drinking water samples and 86% of drinking water sources and systems were below the State's primary health-based standard of 13ppb. Our findings suggest that, although some drinking water supplies in California have been affected by MTBE, the majority of drinking water sources and systems either have not been affected at all or contain MTBE at concentrations below levels that are likely to be of health concern.

MTBE--Panacea or Problem

Methyl tert -butyl ether (MTBE) is an octane-enhancer and oxygenate compound that was authorized as a gasoline additive by the U.S. Environmental Protection Agency (USEPA) in late 1979. MTBE has many chemical and physical properties that make it a desirable compound for these purposes. However, the aqueous solubility of MTBE, which is in the 50,000 ppm range, allows it to dissolve into groundwater where it is transported virtually without retardation. MTBE also is resistant to microbial degradation and does not air-strip from water efficiently. These characteristics have caused wells to become contaminated with MTBE that in the absence would not have become contaminated with hydrocarbons from gasoline releases. Research on innovative technologies to treat water contaminated with MTBE is underway. The final regulatory determination of allowable concentrations and whether or not future use of MTBE will be allowed has yet to be made.

United States experience with gasoline additives

History, benefits and problems associated with gasoline additives in the United States were reviewed. To reduce air toxics and ozone in highly air-polluted areas of the country, oxygenates will continue to be added to gasoline until an alternative is sought and approved by the Congress of the United States. In near future, the use of methyl tert butyl ether (MTBE) will be reduced from its present magnitude and could be replaced by ethanol or other oxygenates that are less harmful to the environment. With rising oil prices, global warming and other environmental issues in the horizon, it is very likely that in the future, hydrogen will substitute gasoline to power electrically driven motors in automobiles. Nevertheless, hydrogen has to be extracted from a readily available source such as gasoline. If gasoline is going to be used as a source of hydrogen, it has to be reformulated from its present form and there will be no need for any additives.

TO MTBE, OR NOT TO MTBE

The curtain is closing on the heyday of methyl tert -butyl ether (MTBE) as a gasoline additive in the U.S.—that much is practically a done deal. MTBE from leaking gasoline storage tanks and fuel spills on pavement is washing into groundwater. Drinking water supplies in wells are becoming tainted with the smelly chemical, which is widely used to meet Clean Air Act standards for cleaner burning gas. But should MTBE's use as a fuel additive be banned or just curtailed? Should the decision be left to states? Should Congress change the section of the Clean Air Act that was at least in part intended to expand ethanol markets but wound up boosting MTBE sales? And if MTBE is out, what is in? Opportunities for rapid growth in ethanol markets loom large, regardless of how these questions are answered. Corn Belt interests, oil refiners, and federal and state regulators agree on that point, but not much else. ...

GETTING THE MTBE OUT

Citing concerns about the environment, low farm commodity prices, and U.S. dependence on imported oil, Clinton Administration officials last week unveiled plans to phase out use of the gasoline additive methyl tert -butyl ether (MTBE) and simultaneously boost sales of ethanol. The Administration is asking Congress to change a Clean Air Act provision that sets the benchmark for oxygen content in reformulated gasoline. This move would eliminate or significantly reduce MTBE use in gasoline. The addition of MTBE increases the oxygen content of gasoline, making the fuel burn cleaner. Use of MTBE has helped improve air quality in a number of cities. However, MTBE is increasingly being found in drinking water supplies, primarily because of leaking underground and aboveground gasoline storage tanks. The substance makes water smell and taste foul even at very low concentrations. EPA classifies MTBE as a possible human carcinogen based solely on inhalation studies. The Administration wants ...

Prediction of isobaric vapour–liquid equilibrium from excess enthalpies for (methyl tert -butyl ether + alkane(s)) mixtures

An effort was made to predict isobaric vapour–liquid equilibrium (VLE) for mixtures containing methyl tert -butyl ether (MTBE) and alkane(s) by using excess enthalpies (HE) previously reported for binary (MTBE + alkane) mixtures at a single temperature. The approach is based on the Gibbs–Helmhotz equation. The prediction was made based on theGE model of Liebermann and Fried, but the temperature dependent parameter k was correlated in terms of the acentric factor of n -alkanes. The predicted vapour compositions and the boiling temperatures for three binary and two ternary systems, obtained from a bubble-point calculation, are satisfactorily compared with the experimental data reported by Wisniak et al. Furthermore, the deviations in the predicted vapour compositions are generally lower than the correlated results as reported by these authors using the equations of Wohl, Wilson, NRTL, and UNIQUAC.

Determination of dichloroacetic acid and trichloroacetic acid by liquid-liquid extraction and ion chromatography.

An extraction technique using MTBE (methyl tert. butyl ether) and reagent water in combination with ion chromatography and conductivity determination was developed to quantify dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) concentrations in raw water after chlorination. The detection limit of the method was 0.45 and 1.50 microg/L for DCAA and TCAA, respectively. Mean values of recovery ranged from 90 to 96% for DCAA and 95 to 108% for TCAA. The evaluation of recovery and precision of the method indicates that the performance characteristics are comparable with gas chromatographic (GC) methods reported in literature. In addition, the procedure is simple, fast, and does not need any derivatization step. Application of the analytical method to the determination of DCAA and TCAA in real samples is shown.

Dynamic Simulation and Control of an MTBE Catalytic Distillation Column

AbstractA dynamic model of an MTBE (methyl tert butyl ether) catalytic distillation column was developed using the SpeedUp simulation package. Experimental kinetic rate data, rigorous thermodynamics, vapour‐liquid nonidealities and tray hydraulics were incorporated in the simulation. The steady state results from the dynamic model were compared with the steady state results from a steady state model developed using the AspenPlus simulation package. The steady state results from the two simulations were in perfect agreement with each other.Open hop step tests were performed on the dynamic model of this process and the process model indicated a non‐linear, self‐regulating behaviour and did not exhibit any multiplicities. Multiloop linear control systems were designed and PI, PID and Dynamic Matrix Control (DMC) controllers were tested on the simulation for load disturbances and setpoint changes.All controllers performed adequately; the DMC controller consistently resulted in better dynamic control performance than the other two controllers.

Oxygenates do little to reduce ozone, NRC finds

Oxygenates used as additives in reformulated gasoline do little to reduce ozone pollution, according to a report released last week by a committee of the National Research Council (NRC). The study looked at the performance of ethanol and methyl tert -butyl ether and found that although gas reformulated with MTBE is slightly more effective at reducing ozone, the impact of both oxygenates is very small. The report, Ozone-Forming Potential of Reformulated Gasoline, notes that vehicle emissions of ozone-forming chemicals have decreased in recent years, but says most air-quality improvements are not the result of oxygenates. Committee Chairman William L. Chameides, Regents Professor of Earth & Atmospheric Sciences at Georgia Institute of Technology, Atlanta, tells C&EN that the lower vapor pressure and sulfur content in reformulated gasoline have had much greater effects than the addition of oxygenates. The 1990 Clean Air Act Amendments require the use of reformulated fuel in areas of the U.S. that have subs...

California MTBE ban hits chemical makers

The decision on March 25 by California's governor to phase out use of the fuel additive methyl tert -butyl ether (MTBE) in gasoline sold in the state has sweeping, and mostly negative, implications for chemical producers. Citing a risk to groundwater from the additive's continued use, Gov. Gray Davis issued an executive order requiring total removal of MTBE from California gasoline by the end of 2002. At the same time, Davis said the state will seek a waiver from the 1990 Clean Air Act Amendments that require California and other states with air pollution problems to add oxygenated compounds to their fuels. Davis and California gasoline suppliers want the waiver because without it, the state will have to replace MTBE with another oxygenate, and currently the only practical alternative is ethanol. Kenneth T. Derr, chairman of Chevron Corp., a leading California refiner, told a press conference last week that Chevron can supply clean-burning gasoline without the ...

Formation of Formaldehyde from Methyl tert -Butyl Ether (MTBE) upon UV Irradiation

Formation of Formaldehyde from Methyl tert -Butyl Ether (MTBE) upon UV Irradiation

Does laser lithotripsy hit the target?

See article on page 823 Ever since it was generally concluded that endoscopic retrograde cholangiopancreatography (ERCP) and sphincterotomy was the treatment of choice for choledocholithiasis, big bile duct stones have...

Methyl tert-butyl ether (MTBE) contamination in private wells near gasoline stations in upstate New York.

Methyl tert-butyl ether (MTBE) contamination in private wells near gasoline stations in upstate New York.