TAME Synthesis

Despite the similar reaction mechanism, a completely different type of behavior was found for the TAME process [71-73]. This is due to the fact that the rate of reaction is one order of magnitude slower for TAME synthesis compared to MTBE synthesis. The behavior of the TAME process is illustrated in Fig. 10.14. In contrast to the MTBE process the TAME column is operated in the kinetic regime of the chemical reaction at a pressure of 2 bar. Under these conditions large parameter ranges with multiple steady states occur. The more detailed analysis by Mohl et al. [73] reveals that steady state multiplicity of the TAME process is caused by self-inhibition of the chemical reaction by the reactant methanol, which is adsorbed preferably on the catalyst surface. Steady state multiplicity is therefore caused by the nonlinear concentration dependence of the chemical reaction rate. Consequently, a similar type of behavior can be observed for an isothermal CSTR. This effect is further in- 

Because of the large multiplicity regions, multiple steady states of the TAME process were also verified experimentally as illustrated in Fig. 10.15 [71, 73, 85). For this purpose suitable startup strategies were developed by means of dynamic simulation to operate the column directly into the desired steady state. Further, it was 

Comparison between theoretical predictions and experimental results showed, that, in contrast to the MTBE process, transport processes inside the catalyst were negligible for the TAME process. This is again due to the fact that the microkinetic rate of reaction is one order of magnitude slower than in the MTBE case and is therefore dominating for the operating conditions considered in this study. This was confirmed more rigorously in a recent paper by Higler et al. [39]. 

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Typical feedstock composition used for tame synthesis. Product performance and properties. 

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... 

Fig. 5.19. Residue curve maps for heterogeneously catalyzed TAME synthesis at operating pressures p = 0.1 MPa and p =1.0 MPa Damkohler numbers Da = 10 10" , and 1.0 ([8], reprinted from Chem. Eng. Sci, Vol 52, Thiel, Sundmacher and Hoffmann, Pages 993-1005, Copyright 1997, with permission from Elsevier Science)...

Fig. 7.20 Schematic of column configurations for TAME synthesis with Raschig rings and Bales in the reactive sections. Adapted from Baur and Krishna [48]...

The reactions are catalyzed by strong acid ion-exchange resins and are usually carried out in the presence of inert components. For MTBE synthesis the iso-olefin is isobutylene and for TAME synthesis the iso-olefins are 2-methyl-l-butene and 2-methyl-2-butene. Further details on the chemistry of etherification processes are given in Chapter 5. 

A. Kolodziej, M. Jaroszynski, W. Salacki, W. Orlikowski, K. Fraczek, M. Kldker, E. Y. Kenig, A. Gorak, Catalytic Distillation for the TAME Synthesis with Structured Catalytic Packings, Chem. Eng. Res. Des., 2004, 82,175-184. 

Baur R., Taylor R. and Krishna R. (2001c). Dynamics of a reactive distillation column for TAME synthesis described by a nonequilibrium stage model. Computer-Aided Chemical Engineering 9, 93-98. 2.9.3, 4.3, 7.2.9, 7.4... 

Modelling and Simulation of Kinetics and Operation for the TAME Synthesis by Catalytic Distillation... 

The simulated reactive distillation unit includes a pre-reactor (adiabatic tubular fixed bed reactor) and the reactive distillation column. The advantage of using a pre-reactor for TAME synthesis is to insure a partial transformation of reactants before RD column, thus increasing the throughput of reaction system. 

Kinetic studies for TAME synthesis were published by Muja et al. (1986), Randriamahefa et al. (1988), Piccoli and Lovisi (1995), Oost and Hoffrnann (1996) Rihko et al. (1995, 1 7), Sundmacher et al. (1999) etc. In this study we us the following reaction rate expressions published by Oost and Hoffrnann, valid for Amberlyst cationit as a catalyst, characterised by an exchange capacity of 5.2 mgUVg ... 

In figure 1 TAME synthesis process flowsheet using catalytic distillation is presented. The C5 fraction is mixed with methanol and the resulting stream is fed to the preliminary reactor (IV). The resulting mixture is mixed with a recycled methanol stream and is fed to a catalytic distillation column, below the reaction zone. 

The simulation results with HYSYS for the TAME synthesis reactive distillation module set-up, presented in this work, allows to draw the following conclusions ... 

This paper presents a theoretical study for the modelling of reactive distillation column operation in TAME synthesis. The simulation results are in a fairly good agreement with experimental data obtained in the experimental pilot plant at SNP PETROM, INCERP Ploiesti subsidiary. 

Experimental and Theoretical Studies of the TAME Synthesis by Reactive Distillation... 

There are several possibilities of immobilising the solid catalyst in industrial CD columns on basis of trays, random and structured packings. A survey on available catalytic column internals is presented by Krishna and Taylor (2000). In this paper structured packing Montz MULTIPAK -2 filled with catalyst Amberlyst 35 WET is applied for the TAME synthesis from light gasoline from the FCC process. 

Commercial MTBE (and TAME) synthesis occurs at about 1.5 MPa and 100°C in the liquid phase over an acid resin catalyst that is based on the sulfonic acid group -SO H. The synthesis reaction is sli tly exothermic and limited by equilibrium under the conditions of the commercial operation ... 

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