Reactive distillation with side draw

We demonstrate the applicability of a new reactive distillation configuration, i.e. reactive distillation with side draw, for certain industrially important reactions. For the reacting systems which involve products with intermediate volatility, a side draw facilitates its in situ removal and enhances either conversion or selectivity. It further reduces the downstream processing in some cases. The concept is proved for three representative systems, viz. esterification of lactic acid, aldol condensation of acetone and for esterification of fatty acid by methanol. Experimental proof is also provided in some cases.© Elsevie

Attainable regions of reactive distillation-Part I. single reactant non-azeotropic systems

Reactive distillation (RD), a promising multifunctional reactor, can be used to improve the selectivity of the desired product by manipulating the concentration profiles in the reactive zone of the column. In this work, a new approach has been proposed to obtain the feasible regions of RD for the reactive systems involving single reactants, e.g. dimerization, aldol condensation, etc. Two new models namely the reactive condenser and the reactive re-boiler have been proposed. These models indicate the best location of the reactive zone in a column. Multistage versions of these models namely, reactive rectification and reactive stripping further expand the feasible region and are capable of representing the performance offered by a conventional RD unit. Several hypothetical non-azeotropic ideal systems have been extensively studied using these models and it has been shown that selectivity close to 100% is attainable over the entire range of conversion for a series as well as a combination of series and parallel reactions with positive reaction orders. Two industrially important cases of aldol condensation of acetone and dimerization of isobutylene have also been addressed using this approach. For porous catalysts, the presence of intra-particle diffusion resistance may limit the feasible region and even in the case of ideal non-azeotropic systems it may not be possible to obtain 100% selectivity. A methodology to incorporate pore diffusion effects is also illustrated.© Elsevie

Simultaneous production of diacetone alcohol and mesityl oxide from acetone using reactive distillation

Dimerization of acetone (Ac) yields diacetone alcohol (DAA), which on further dehydration gives mesityl oxide (MO) along with various side-products. The reacting system is a combination of various series and parallel reactions. In the present work, the reaction is studied using a cation exchange resin (Amberlyst 15®) as catalyst. The effect of catalyst loading and temperature on reaction kinetics was evaluated and three models based on simplified Langmuir–Hinselwood mechanism are proposed. Aim of the work is to minimize undesired side-products and understand the effect of different parameters and operating modes on DAA:MO product ratio in reactive distillation (RD). It has been shown that the reaction when operated in a reactive rectification mode offers flexibility in the relative production rates of DAA and MO. The experimental results obtained are explained by simulation.© Elsevie

Attainable regions of reactive distillation. Part II: single reactant azeotropic systems

In reactive distillation (RD) one can conveniently manipulate the concentration profiles on the reactive stages by exploiting the difference in volatility of the various components. This property of RD can be advantageously used to improve the selectivity toward the desired product in case of series or series parallel reactions, and obtain a performance superior to the network of conventional reactors. In the previous work [Agarwal, V., et al., 2008. Attainable regions of reactive distillation-Part I. Single reactant non-azeotropic systems. Chemical Engineering Science, submitted for publication], we introduced representative unit models of RD to obtain the attainable regions of RD for non-azeotropic systems. In this work, we extend the approach to a system involving single binary azeotrope. Design guidelines have been formulated based on the residue curve maps, to obtain the improved attainable region with the help of these representative RD models either alone or in the form of their network.© Elsevie