Methyl acetate synthesis

In this section, four examples illustrating the application of the rate-based approach discussed above to the RD modeling are presented. The systems selected are methyl acetate synthesis, MTBE synthesis, ethyl acetate synthesis and transesterification of dimethyl carbonate. In the first example, dynamic process modeling is highlighted, whereas in three other examples, different aspects of steady-state modeling are discussed. 

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Figure 5 Methyl acetate synthesis conventional scheme. (From Ref. 33.)...

The low equilibrium constant and the strongly nonideal behavior that causes the forming of the binary azeotropes methyl acetate/methanol and methyl acetate/ water make this reaction system interesting as a possible RD application (33). Therefore, methyl acetate synthesis has been chosen as a test system and investigated in a semibatch RD column. Since the process is carried out under atmospheric pressure, no side reactions in the liquid phase occur (146). 

Methyl Acetate Synthesis, Steady-State Distillation... 

Figure 27 Liquid-phase composition profiles along the 50-mm-diameter catalytic distillation column for methyl acetate synthesis at reflux ratio of 2.0 and different reboiler duties (a) 295W (b) 873W (c) 1161W.

Gorak A, Hoffmann A. Catalytic distillation in structured packings methyl acetate synthesis. AIChE J 2001 47 1067-1076. 

Song W, Venimadhavan G, Manning JM, Malone MF, Doherty MF. Measurement of residue curve maps and heterogeneous kinetics in methyl acetate synthesis. Ind Eng Chem Res 1998 37 1917-1928. 

A temperature rise above 680 °C (at r = 0.45 s) induces allene and methyl acetate synthesis by propylene conjugated dehydrogenation reaction (refer to Figure 4.3), the yield of which under optimal conditions equals 20% and 10%, respectively [62],... 

In the forward direction the ester is formed, and in the reverse direction it is hydrolyzed. For esterification, the alcohol can be used as a solvent as described for methyl acetate synthesis [26]. For ester hydrolysis, water can be used as a solvent, as described for hydrolysis of methyl formate, ethyl formate, methyl acetate and ethyl acetate [28]. Usually, the solvent is taken in large excess and it can be assumed in good approximation that its concentration is constant. For constant alcohol... 

Hydrogenation of 1,3,5-trimethylbenzene Methanol synthesis Ethyl acetate synthesis Methyl acetate synthesis Propene metathesis. 

There are many examples of the application of CD or RD for esterification.f" Esterification of methanol or ethanol with acetic acid forms methyl acetate or ethyl acetate, respectively. Methyl acetate is important in the manufacture of polyesters and is an important solvent for cellulose while ethyl acetate is used in inks, fragrances, and pharmaceuticals. The manufacture of high-purity methyl acetate is difficult because of the equilibrium limitation and also the formation of azeotropes. The production of methyl acetate by Eastman Chemical Co. was the first commercial application of RD using a homogeneous liquid acid catalyst. Only one RD column and two smaller columns for processing sidestreams are required while in the conventional methyl acetate synthesis, two reactors and eight distillation columns are required. 

Figure 3.7 Process of methyl acetate synthesis without (a) and with (b) reactive distillation.

Carbonylation of methyl acetate, developed in particular by Hakoru This method is based on the use of synthesis gas to produce successively methanol, methyl acetate, and acetic anhydride jointly with ethyiidene diacetate, which then decomposes to vinyl acetate and acetic add, which is recycled to methyl acetate synthesis. The overall reaction is the following ... 

Figure 7.30 Reactive Distillation and conventional process for methyl acetate synthesis...

Figure 10.5 Flow sheet of the catalytic RD column for methyl acetate synthesis (taken from [84]).

For the methyl acetate synthesis, dynamic modeling effects are investigated, whereas for other systems, the focus is on different steady-state issues, for example the influence of liquid-liquid separation, operational conditions and different column internals (ethyl acetate) or selectivity effect (dimethyl carbonate transesterification). The comparison between the simulation and experimental data made for all RD case studies proves that the rate-based approach is capable of predicting correct process behavior, both steady state and dynamic. 

A. Gorak, A. Hoffmann, Catalytic Distillation in Structured Packings Methyl Acetate Synthesis, AIChE Journal, 2001, 47, 1067-1076. 

W. Song, G. Venimadhavan, J. M. Manning, M. F. Malone, M. F. Doherty, Measurement of Residue Curve Maps and Heterogeneous Kinetics in Methyl Acetate Synthesis, Ind. Eng. Chem. Res., 1998, 37,1917-1928. 

Penkova (2013) studied the methyl acetate synthesis reaction by PVMRs. Membranes with a base of poly-(2,6-dimethyl-l,4-phenylene oxide) (PPG) were used in an SBR configuration in particular, a homogeneous PPG membrane and a... 

Horstmann, S. Poepken, T. GmehUng, J. Phase equilibria and excess properties for binary systems in reactive distillation processes. Part I. Methyl acetate synthesis Fluid Phase Equilib. 2001,180, 221-234... 

Methyl acetate synthesis rate does not depend on DME pressure, but increases linearly with CO pressure up to 10 atm. This kinetic response is consistent with a sequence of elementary steps (Fig. 6) involving the formation of surface methyl groups at Brpnsted acid sites initially via direct DME reactions with protons and then via chain transfer reactions (propagation steps) of DME with surface acetyls formed via rate-determining CO insertion into C-0 bonds in methyl groups at the catal3rtic steady state (92). CO insertion occurs from the gas phase or via weakly held CO species adsorbed noncompetitively with CH3 groups. 

Venimadhavan (1994) presented the heterogeneous kinetics for methyl acetate synthesis. He has developed a Langumuir - Hinshelwood - Hougen-Watson model to represent reaction kinetics. Isothermal batch kinetic experiments were performed using heterogeneous catalyst (Amberlyst 15) at temperatures of 313 K - 323 K. Also, independent binary adsorption experiments were performed to estimate the adsorption equilibrium constants. 

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