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Abstract

A microplant concept is introduced for the analysis of homogeneously and heterogeneously catalyzed liquid phase reactions. Esterification of acetic acid with butanol is considered as a benchmark problem. The plant configuration includes a micromixer (SIMMV-2, IMM Mainz, Germany), which mixes the reactants fed at the reaction temperature (200C, 60-800C) followed by the microreactor. For the case of homogeneously catalyzed esterification, a long tube of 1mm inner diameter acted as the reaction tube with reasonable residence time. The results from the experiments for the range of temperature and the different catalyst concentrations were consistent with the published literature. For the case of hererogeneously catalyzed esterification a micro fixed bed reactor ( FBR) was designed by stacking and connecting several reaction plates on which several micro-channels were created through micro-machining. Amberlyst-15 was used a catalyst and filled in the reactor channels (1.43m total length). The pressure drop across the length of the reactor was not very high even in the swollen condition of the catalyst particle. The reactor gave excellent conversion rates at steady state and the performance of the FBR was consistent for very long time (over 42hrs of continuous operation). A change in the residence/reaction time and the reactive length was achieved by changing the total flow rate and the number of reaction plates, respectively. The microplant is flexible in terms of desired residence time, amount of the catalyst, particle size and the flow rates. The FBR developed in this investigation offered the following advantages: (i) the system can be maintained practically isothermal, (ii) due to the very long active life of the catalyst, the reactor needs not to be disassembled frequently, (iii) the mole ratio of the reactants can be modified externally, (iv) the system is suitable for the analysis of the dynamics of this adsorption enhanced reaction. (v) The concept is simple and yet gives flexibility in extending this design for achieving a continuous small-scale production facility.