Synthesis of TAME

TAME is produced by liquid-phase synthesis from methanol and isoamylenes. Among the three isoamylenes only 2-methyl-l-butene (2MB1) and 2-methyl-2-butene (2MB2) are reactive in etherification 3-methyl-1-butene (3MB1) is non-reac-tive. Besides the two synthesis reactions, the isomerization of the reactive isoamylenes takes place simultaneously [10] 

To calculate residue curve maps for the synthesis of TAME one has to proceed in the same manner as the MTBE example and calculate phase equilibria bet veen liquid and vapor phases, chemical equilibrium constants in the liquid phase, and kinetics of the chemical reactions. 

Because there are three reactions taking place, three coupled chemical equilibria have to be considered. Rihko et al. [11] proposed the following expressions, which are based on their experiments (T in K) 

Oost and Hoffmann [10] have developed a kinetic expression for the TAME synthesis of the lumped C5-reactants 2MB1 and 2MB2 in terms of liquid-phase activities 

For the sake of a simplified illustration, the mixture of isomers 2MB1 and 2MB2 is treated as one pseudo-component isoamylene (lA) so that its mole fraction is = 

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The existence of multiple steady states has attracted the attention of several researchers [2]. Simulation studies indicated that the same column configuration operating under similar conditions can give rise to different steady-state conversions. Bravo and co-workers reported the only experimental evidence of multiple steady states in the synthesis of TAME in the pilot plant of Neste Oy [3]. The MTBE system also shows oscillatory behavior, as reported by Sundmacher and Hoffmann [2]. 

Baur R. and Krishna R. (2002). Hardware selection and design aspects for reactive distillation columns. A case study on synthesis of TAME. Chemical Engineering and Processing 41, 445-462. 2.6, 2.9.3,... 

The relevant models for the reactive distillation column and peripherals have been developed and implemented into the simulation environment ASPEN Custom Modeler . Simulations of the heterogeneously catalysed synthesis of TAME have included 11 components. The species and the boiling points at the operating pressure of 4 bar are listed in Table 1. The key components of the inert fractions of the feed have been used to represent the hydrocarbon fractions (see Table 1). VLE is described by UNIQUAC model, with the Redlich-Kwong equation of state. In simulations, four reactions are considered the main reactions (l)-(3) and the formation of dimethyl ether (7). 

Both experimental and theoretical studies on the synthesis of TAME via reactive distillation have been performed. A rigorous model including 11 components and 4 reactions has been developed. The agreement between simulation and experiments is satisfactory. Simulations studies show a significant influence of the reflux ratio on conversion and selectivity for TAME related to methanol. 

The two-film model representation can serve as a basis for more complicated models used to describe heterogeneously catalyzed RSPs or systems containing suspended solids. In these processes a third solid phase is present, and thus the two-film model is combined with the description of this third phase. This can be done using different levels of model complexity, from quasi-homogeneous description up to the four-film presentations that provide a very detailed description of both vapor/gas/liquid-liquid and solid/liquid interfaces (see, e.g., Refs. 62, 68 and 91). A comparative study of the modeling complexity is given in Ref. 64 for fuel ether synthesis of MTBE and TAME by CD. 

Selective Hydroboration and Synthetic Utility of Organoboranes Thus Obtained TaMe 3. Synthesis of Unsymmetrical Ketones via Thexyldialkylboranes... 

Condensation of [Co(tame)2]3+ cation with propanal is described in more detail in Ref. 152. The resultant [Co(/ ac-Me5tricosanesar)]3+ sarcophaginate was demetallated, and the free ligand was employed for the synthesis of a chromium(III) sarcophaginate with unusual spectral characteristics (Scheme 68) [153]. 

Processes based on these catalysts could provide isobutene and isopentene for the synthesis of MTBE (methyl tert-butyl ether) and TAME (tert-amyl methyl... 

The application of the method for the synthesis of MTBE, TAME and other octane improvers for gasoline is proposed. An application of the method to branch alkenes synthesised by a selective Fischer-Tropsch catalyst is demonstrated. 

The light alkenes (propene, butene and pentene) are important feedstocks for alkylation, oligomerization and the synthesis of ethers (refs. 1,2). MTBE (methyl tert-butyl ether) and TAME (tert-amyl methyl ether) have research octane numbers of 118 and 112 respectively. These premium blend stocks are synthesised by reaction of methanol with isobutene or isopentene (refs. 3,4). The reaction with methanol is selective towards the branched alkenes so that a mixture may be treated and the straight chain alkenes recovered for other processing such as alkylation. 

A particularly favourable application would be in the synthesis of MTBE and TAME. The selective reaction of methanol with the branched alkene would enable the straight chain alkenes to be recycled through the isomerization catalyst. Since the methanol for such a process would likely be synthesised from CO and Hg it would be possible to run this process in parallel with an alkene selective Fischer-Tropsch process to achieve a self contained conversion of CO and to a high octane fuel blend stock. 

Residue curve maps and parametric dependencies similar to those reported for the MTBE and TAME system were also obtained for the heterogeneously catalyzed synthesis of the alternative fuel ether ETBE from isobutene and ethanol [12]. 

In order to formulate an expression x) in (5.57), the rate determining step of the reaction mechanism has to be identified. For many heterogeneously catalyzed liquid-phase reactions the rate limiting step is found to be the reaction of sorbed molecules. For example, in the synthesis of the fuel ethers MTBE, TAME, and ETBE at acid ion-exchange catalyst the rate limiting step can be expressed as follows... 

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