Dimethylacetal also named as acetal or 1,1-dimethoxyethane (DME) ia an important raw material using at commercial scale and in laboratory research. Importantly, this is used for the manufacture of fragrances and pharmaceutical products. It is not only used as the raw material, but also as an important intermediate for the synthesis of various industrial chemicals, used as organic solvent, used for the design of synthetic perfumes and for the production of polyacetals(Aizawa, et al., 1994), used as an oxygenated fuel additive(Tao, et al., 2001). Acetalization reactions can be performed by reversible liquid-phase reaction(Viviana, et al., 2000) and DME synthesis was performed with methanol and acetaldehyde reaction, which reaction was performed on acidic homogeneous and hetrogeneour catalysts(Henri, 1932; Rodriguez, et al., 2000). The aim of the present work is to develop a process for the synthesis of dimethylacetal from methanol and acetaldehyde reaction, and sulfonic acid ion exchange resin Amberlyst-15 as catalyst and as well as an adsorbent in the Simulated Moving Bed Reactor (Silva and Rodrigues, 2005). Batch Reactor: Experiments have been performed in a laboratory-scale jacketed glass reactor(1 dm3) in the temerature range of 20-60 oC, at 6 atmospheres pressure. Reaction of methanol and acetaldehyde were performed with three different solid catalysts in order to observe the performance of the catalyst. Figure 1(a) shows the conversion of limiting reactant acetaldehyde along the time of reaction. Kinetics and thermodynamics were studied for the above reaction with Amberlyst-15. Different effects like effect of particle size, effect of agitation, amount of catalyst, initial reactants molar ratio, temperature and pressure on the reaction rate were studied. Figure 1(b) shows the typical reaction profiles.A two-parameter model based on a Langmuir-Hinshelwood rate expression, using activity coefficients from the UNIFAC method is proposed. This model was extended in order to include external and internal mass transfer resistances and it is able to predict the experimental kinetic results obtained in a batch reactor. Fixed Bed Adsorptive Reactor: Secondly, experiments have been performed in a laboratory-scale jacketed glass column(26mm ID, 120mm length) packed with Amberlyst-15. Reaction experiments were performed at 20 oC and atmospheric pressure. To obtain model parameters, binary adsorption experiments were organised in absence of reaction. The model for the adsorptive reactor includes axial dispersion, external and internal mass-transfer resistances, constant temperature and multicomponent Langmuir Isotherms, and model equations were solved by orthogonal collocation in finit elements method, which was implemented in the PDECOL package, using the measured model parameters. The breakthrough curves of methanol, dimethylacetal, and water were measured at 20 oC, and atmospheric pressure. The resin bed was saturated with certain component A, then the feed concentration of component B was changed stepwise. The obtained breakthrough curves were fitted with results of numerical simulations. The multicomponent equilibrium adsorption relationship was assumed to follow the modified Langmuir type. Reaction experiments were performed by feeding the methanol saturated packed column with a mixture of methanol and acetaldehyde, where reaction takes place. Figure 2 shows the reaction profiles along the time in a Fixed Bed Adsorptive Reactor. Simulated Moving Bed Reactor:With the above results from the Batch Reactor and Fixed Bed Adsorptive Reactor experiments, it is now possible to design and to optimize an efficient process in a integrated unit, which uni is a combination of reaction and separation units, so-called Simulated Moving Bed Reactor(SMBR). The Simulated Moving Bed Reactor (SMBR) for the synthesis of dimethylacetal dimethylacetal was studied experimentally and with simulations. The experimental results are compared with the TMBR modeling strategy Figure 3. The effect of switching time and the configuration of the SMBR was studied. The mathematical model assumes axial dispersion flow for the bulk fluid phase, plug flow for the solid phase, linear driving force (LDF) for the particle mass transfer rate and multicomponent adsorption equilibria. The stationary steady-state predicted from the TMBR model is in agreement with the experimental SMBR cyclic steady-state at the middle of the switching time behavior, in terms of internal concentration profiles.

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