Abstract  The gas-phase synthesis of ETBE from ethanol and isobutene has been carried out over a H-ZSM-5 catalyst in two types of continuous-flow catalytic reactors, fixed-bed and fluidized-bed. We have studied the influence of temperature, molar ratio ethanol/isobutene and weight hourly space velocity on the yield of ETBE.

Abstract  Synthetic resins are one of the most used catalysts in the production of additives for gasoline fuelled cars. Ethers like MTBE (methyl-t-butylether), TAME (t-amylmethylether) or ETBE (ethyl-t-butylether) are now widely used to enhance the anti-knock performance of the fuels. Now more than 14,000,000 t per year of the above-mentioned ethers are produced world-wide. On the other hand there is much less use of catalytic ion exchange resins in the production of fine chemicals. Reasons might be selectivity aspects, the availability of resins in a shape which is well suited for technical reactors and a lack of knowledge with respect to the accessibility and stability of the active sites. In this study the preparation and characterisation of polymer/carrier composite components for catalytic applications is described. Monolithic rods for chemical reactions with simultaneous separation were prepared by a precipitation polymerisation process and investigated. The distribution of the cross-linker concentration across the particle radius is calculated based on co-polymerisation parameters and discussed. The active sites are sulfonic acid groups. The distribution of the active sites was measured by scanning electron microscopy. For the cyclisation reaction of 1,4-butanediol to tetrahydrofuran and water the application of rods as a monolithic chemical reactor was demonstrated.

Abstract  With the introduction of the catalyst technique in the 80s and the associated necessity to offer lead free gasoline methyl tertiary butyl ether (MTBE) was added as the anti-knock improver. However, recently MTBE increasingly turns into the focus of interest, because it was found in groundwater in the USA. In concentrations of 30 mug/l MTBE has a strong unpleasant smelling and it is under suspicion to be carcinogenic. It is it prohibited as additive for gasoline in California since 2002. Alternatively ethyl tertiary butyl ether (ETBE) can also be used to increase the anti-knock behaviour. If ETBE is produced from bioethanol, it is indirectly a good application of an oxygen-containing renewable energy source. In France the use of ETBE is already subsidised by tax exemptions. However, only the renewability of a fuel or a fuel's component does not justify the application, because the combustion process can lead to a lot of hazardous components in the exhaust. So the emissions and their effects on human health have to be analysed for renewable fuels as well. In a preliminary study health relevant emissions from the combustion of fuels containing ETBE- were analysed and compared with commercial fuels. Especially the emissions of benzene, toluene, ethyl benzene and xylenes (BTEX) and the mutagenicity and cytotoxicity of the particulate matter and the condensed phase of the exhaust gas were analysed. The investigations were carried out at an Opel gasoline engine. It was fueled with different blends of gasoline/ETBE. The ETBE content varied between 0 and 30%. In the result the emissions of BTEX decrease with increasing ETBE content in the fuel. Comparing ETBE-gasoline with commercial fuels, high emissions of toluene by Optimax(R) and of xylene by DEA gasoline were noticeable. Mutagenicity and cytotoxicity were found to decrease when gasoline is blended with ETBE. Furthermore the mutagenicity of the emissions of Optimax(R) is noticeable lower than of gasoline without ETBE.

Abstract  Consistent vapor-liquid equilibria data have been determined for the ternary system oxolane (THF) + ethyl 1, 1-dimethylethyl ether (ETBE) + 2-propanol at 50 kPa, in the temperature range 320-333 K. The measurements were made in an equilibrium still with circulation of both the vapor and liquid phases. The system exhibits positive deviation from ideal behavior and no ternary azeotrope is present. The activity coefficients and boiling points of the solutions were well predicted with the mole fraction by the Wilson, NRTL, and UNIQUAC equations, using binary parameters only.

Abstract  Reactive distillation is a favourable alternative to conventional series of reaction-separation processes. It can reduce both operating costs as well as capital investments. However, its control is challenging due to its complex dynamics resulting from its integrated functionality of reaction and separation. Linear, e.g. PID, control with fixed parameters has been shown not to be satisfactory to handle its high nonlinearity. It needs to be re-tuned adequately over a wide range of operating conditions. In this work, the application of two adaptive PI control strategies, e.g. non-linear PI (NPI) and model gain-scheduling (MGS), is investigated for an ETBE reactive distillation column. Their control performance to handle the nonlinearity and reduce the unwanted variability is discussed. The simulation results show that the proposed control strategies outperform a standard PI controller in both set-point tracking and disturbance rejection.

Abstract  Reactive distillation is a novel technology that has been successfully used in the production of ether fuel additives. This process integrates reaction and separation in a single unit-operation. The interaction of reaction and separation makes the process exhibit complex behavior such as process gain nonlinearity, significant interactions, process gain bidirectionality (i.e., process gain sign change), and steady-state multiplicity. These complex dynamics make process control of the reactive distillation column very difficult. In this work, the nonlinearity of an ETBE reactive distillation column was investigated, and a 2 x 2 unconstrained model predictive control scheme was developed for the product purity and reactant conversion control. The process dynamics were aroximated by a first-order plus dead time model to estimate the process model for the model predictive controller. The model predictive controller was able to handle the process interactions well and was found to be very efficient for disturbance rejection and set-point tracking. This controller was stable and performed robustly in the presence of process measurement noise.

Abstract  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.

Abstract  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 Bronsted 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.

Abstract  Densities and refractive indices at 298.15 K are reported for the binary systems ethyl tert-butyl ether (ETBE) + ethanol, ethanol + benzene, and ETBE + benzene and the ternary system ETBE + ethanol+ benzene. The excess molar volumes and deviations in molar refractivity were derived and correlated with the Redlich-Kister and Cibulka equation for the binary and ternary systems, respectively. The binary data were compared with the values in the literature, and the ternary data were compared with the predicted values using the Tsao-Smith, Kohler, Rastogi and Radojkovic binary contribution models.

Abstract  A detailed chemical kinetic mechanism has been developed for the oxidation of primary reference fuel (PRF, mixture of n-heptane and iso-octane) in the presence of ethyl tert-butyl ether (ETBE) or ethanol. The mechanism was validated by comparison with the existing experimental data from shock tubes, a jet-stirred reactor, and a flow reactor. ETBE and ethanol are known as octane number improvers. Enhancement of research octane number (RON) by the addition of ETBE and ethanol to PRF has been measured using a cooperative fuel research (CFR) engine. Increase in RON was simulated with the present detailed kinetic mechanism by estimating the critical compression ratio (CCR) for autoignition in a motored engine. The correlation curve between CCR and RON was derived by calculating the CCR for PRF whose composition defines the RON. The kinetic model reproduces observed variations in RON by the addition of ETBE and ethanol to PRF. Those additives showed a very similar effect on RON.

Abstract  Ethyl-tert-butyl ether (ETBE) was converted by hydrogen peroxide in the presence of HCL, NaCL, H2SO4 and citric acid in aqueous medium under UV radiation. The strong inhibiting effect of hydrochloric and sulfuric acids on ETBE conversion was observed. Citric and hydrochloric acids inhibited the oxidative conversion of the etheronly to a small extent, while sodium chloride accelerated the conversion.

Abstract  Vapor-liquid equilibria, data containing ethyl 1, 1-dimethylethyl ether (ETBE) as an ether synthesized from ethanol of biological origin, are presented giving isothermal p-x-y data for the ternary system ethyl 1, 1 dimethylethyl ether (ETBE) + 1-hexene + cyclohexane and the two binary systems involved containing the ether at 313.15 K. A static technique consisting of an isothermal total pressure cell was used for the measurements. Data reduction by Barker's method provides correlations for G, using the Margules equation for the binary systems and the Wohl expansion for the ternary system. Wilson, NRTL, and UNIQUAC models have also been alied to both binary and ternary systems. The mixtures measured exhibit a slight positive deviation from ideal behavior.

Abstract  The densities and ultrasonic velocity of the binary mixtures methyl tert-butyl ether (MTBE) or ethyl tertbutyl ether (ETBE)+(o-xylene, m-xylene and p-xylene) at the range 288.15-323.15 K and atmospheric pressure, have been measured over the whole concentration range. The experimental excess volumes and deviation of isentropic compressibilities data have been analyzed. The experimental values have been studied in terms of different theoretical models. The gathered data improve open literature related to gasoline additives, as the comparison has proved, and help to understand the ether effect into aromatic environment in terms of steric hindrance and oxygen group polar potency. (C) 2008 Elsevier B.V. All rights reserved.

Abstract  Ethyl tert-butyl ether (ETBE) is produced by commercial processes to a purity of up to 96%. In recent years, several companies have started to produce ETBE, increasing the demand for standards with higher grades of purity in the area of production control and final product certification. The present work involved the development of a purification protocol for obtaining high purity ETBE from the commercial product used in the formulation of automotive gasolines, using a spinning band distillation column. The ETBE thus produced showed a purity of over 99.5%, its main contaminant being its isomer, ethyl-sec-butyl ether (ESBE).

Abstract  The near-threshold absolute photoionization cross-sections of 12 oxygenated hydrocarbons, including 1-butanol, 2-butanol, iso-butanol, tert-butanol, 1-pentanol, tert-pentanol, iso-pentanol, methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), furan, 2-methylfuran, 2,5-dimethylfuran, were measured in the photon energy range from respective ionization thresholds to 11.5 eV. The experiments were performed with photoionization mass spectrometry and tunable synchrotron vacuum ultraviolet (VUV) light. Binary-liquid-mixtures of the investigated sample and benzene were used in the measurements where benzene acts as a calibration standard, due to its well known photoionization cross-section at the photon energies from its ionization energy (9.24 eV) to 11.5 eV. Photodissociative fragments from the molecules were also observed, and their photodissociation cross-sections are also presented.