ETBE Properties

ETBE is a valuable component for gasoline, with properties similar to, and in some cases better than, MTBE (Table 11.1). ETBE has, in fact, the same blending characteristics as MTBE but it has the additional benefits of a lower solubility in water, a lower volatility (some additional light compounds can be introduced in the gasoline pool without affecting its RVP) and moreover it allows a higher plant production capacity (16% wt). 

Bioethanol is also a very attractive compound for increasing gasoline octane quality and it can be added up to 10% to gasoline (E5 is the preferred European solution while ElO is used in USA) without engine modification or also used practically pure, as E85 or ElOO, in the Flexible Fuels Vehicles. 

With respect to ETBE, ethanol has, however, some disadvantages such as volatility and water solubility. Its RVP is more four times that of ETBE and it adversely affects the gasoline volatility in fact, ethanol addition causes a significant reduction in temperature for the front end evaporation and, as a consequence, the light cheap gasoline components, such as butanes and pentanes, have to be removed to meet the volatility specification limit. 

Another important issue of ethanol is its water sensitivity, which affects the water tolerance of gasoline in the case ofwater presence in ethanol-added gasoline, there is, in fact, the formation of hydrogen bonds between water and alcohol and the blend separates into two phases, with loss of octane quality. As a consequence, bioethanol requires special handling with different storage and distribution facilities for alcohol and gasoline and the blend has to be carried out just before the final use. 

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Typical feedstock composition and product properties for the synthesis of MTBE-ETBE. 

Oxygen was added as oxygenated hydrocarbon components methyl tert-butyl ether (MTBE), tert-amyl methyl ether (TAME), ethyl tert-butyl ether (ETBE), di-isopropyl ether (DIPE), ethanol, methanol, and tertiary butyl alcohol (TBA). The properties of oxygenates, as they relate to gasoline blending, are shown in Table 10-1. 

Loss of Coordinated Arene. We previously stated that the arene ligand in ruthenium(II)-arene complexes is relatively inert towards displacement under physiological conditions. While this is generally true, there are a few exceptions to this rule and this type of reactivity can be used to advantage. Weakly bound arenes, for instance, can be thermally displaced, a property convenient for the synthesis of ruthenium-arene complexes that are not readily available through more common synthetic routes. This way, the reaction of a precursor dimer, [RuCl2(etb)]2 (etb, ethylbenzoate) (68), with either 3-phenyl-1-propylamine or... 

In addition to MTBE, two other ethers commonly used as fuel additives are tert-xcayi methyl ether (TAME) and ethyl tert-butyl ether [637-92-3] (ETBE). There are a number of properties that are important in gasoline blending (see Gasoline and other motor fuels) (Table 3). 

The main use of MTBE is as an octane booster in gasoline formulations. Table 2.1 (above) compares octane number and boiling points of some tertiary ethers and hydrocarbons. The volatility is another important property of gasoline components. In fact, the lower volatility of ETBE is an advantage with respect to MTBE. Another (smaller scale) application of MTBE is the synthesis of high purity isobutene by cracking MTBE over amorphous silica-alumina. This isobutene serves as a monomer for polyisobutene. 

Selective ETb antagonist properties have been claimed in a Banyu patent for at least one example, la (19) in a series of linear ET-1 analogues (ICjo = 1300 nM against ET and 1.1 nM against ETb, in binding assays) [128] but no information from functional assays is available. 

In this scenario biodiesel, bioethanol and ETBE (ethyl tert-butyl ether), the ether obtained from bioethanol and isobutene, are the compounds normally utilized as fuels. In particular, ETBE is playing an increasingly important role in the gasoline pool composition owing to its superior properties, which represent a trade-off between the needs of refiners and the severe expectations and regulations of environmental stakeholders. 

One or more plasmids are usually found in clinical isolates of S. aureus. There are at least three families of S. aureus plasmids (Novick 1990), which are classified into fifteen incompatibility groups (Novick 1987). Most plasmids that have been desaibed encode antimicrobial resistance determinants, and some have also been attributed other clinically significant properties, such as toxin production (e.g. entero-toxins SED and SEJ, and exfoliative toxin ETB), whereas some staphylococcal plasmids are phenotypically cryptic. 

ETBE is made from com ethanol, a domestic renewable oxygenate. This could drastically cut down the dependence on oil imports. As an ether, ETBE displays superior water tolerance properties and can be shipped by pipeline. 

Table 1 Basic properties of ETBE compared with MTBE (data from http //www.efoa.org)...

It is important to understand the impact these compounds can have on human health because of the potential for exposure to the general public. The toxicology of MTBE and ETBE has been reviewed previously [2-6]. ETBE is currently also under review for risk assessment by the European Union (rapporteur Member State, Finland). Since the structures of ETBE and MTBE are very similar, it is expected that there will also be similarities in their toxicological properties. Sometimes, this may allow gaps in the database for ETBE, which has been less extensively studied, to be tentatively supplemented with data derived from studies with MTBE. 

Most important industrial applications of RD are in the field of esterification processes such as the famous Eastman Chemical Co. s process for the synthesis of methyl acetate [1]. This process combines reactive and non-reactive sections in a single hybrid RD column and thereby replaces a complex conventional flowsheet with 11 process units. With this RD technology investment and energy costs were reduced by factor five [2]. Another success story of RD was started in the 1980s by using this technology for the preparation of the ethers MTBE, TAME, and ETBE, which are produced in large amounts as fuel components because of their excellent antiknock properties [3]. 

In Germany, however, bioethanol will mainly be used as low blend of bioethanol and petrol (E5, ElO) and for the production of ETBE (ethyl-tertiary-butyl-ether). Similar to methyl-tertiary-butyl-ether (MTBE), ETBE is used to enhance the octane index and improve knock-resistance and combustion properties of gasoline." It is less challenging to handle, does not induce evaporation of gasoline and does not absorb moisture like ethanol does. ETBE is produced by reacting ethanol and isobutylene via acid catalyst ... 

Consider ethyl-tertiary-butyl-ether (ETBE) as an alternative gasoline oxygenate to MTBE. While the latter appears to have the best combination of properties such as oxygen content, octane number, energy content, and cost, the former can be manufactured using ethanol according to ... 

Property MTBE ETBE TAME TAEE DIPE Methanol Ethanol Tertiary-butyl alcohol Isopropanol... 

TAME has chemical and physical properties that are similar to those of MTBE and ETBE. As expected from its molecular structure, the properties of TAME are closer to gasoline than those of MTBE and ETBE. TAME is miscible with gasoline in all proportions, TAME-gasoline blends are water tolerant (the addition of water does not induce phase separation as with ethanol-gasoline blends Mueller et al., 2009) and can be distributed via pipelines in blends with gasoline, has a high octane number (blending octane number of 112, see table I-E-1), and solubility in water of 11 g liter" ... 

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