distillation systems are solved by present flowsheet programs. Thissoftware module has been implemented into a flowsheet simulatorenvironment that contains all required physical and chemical databanks and enables large-scale process optimisation. The applic-ability of the new module is demonstrated by solving two presentlyinteresting processes: production of MTBE and iso-octene. Themodel has shown good convergence properties.

571

State-of-the-Art and Future Challengesin Design of Reactive DistillationProcesses

A . T u c h l e n s k i 1

D . R oÈ t t g e r 2

D . R e u s c h 1

A . B e c k m a n n 2

1 Degussa AG, Verfahrenstechnik & Engineering, D-45764 Marl

2 Degussa AG, Oxeno C4-Chemie, D-45764 Marl

Currently, there is considerable industrial interest in multifunc-tional reactors involving in-situ separation of products from thereactants. Reactive distillation is one of the most promising candi-dates for in-situ product removal. There are two major benefits ofreactive distillation operation. First, higher conversion due to shift-ing the equilibrium to the product side. Second, improved selectiv-ity due to removal of products from the reaction zone. Althoughreactive distillation involves more process risks in practice thanthe sequential processing it might be a key to competitiveness inchemical industry. From this point of view a rapid progress in hy-brid technology can be expected in the future. This review illus-trates gaps and future challenges in the design of industrial reac-tive distillation processes.

572

Liquid Phase Mass Transfer withinKATAPAK-S Structures Studied UsingCFD Simulations

J . M . v a n B a t e n

R . K r i s h n a

Department of Chemical Engineering, University of Amsterdam,Nieuwe Acthergracht 166, 1018 WV Amsterdam, The Netherlands

The liquid phase mass transfer within the catalyst-packed criss-crossing sandwich structures of KATAPAK-S has been studiedwith the use of computational fluid dynamics (CFD). Due to theªupheavalº caused by the flow splitting at the cross-overs, themass transfer coefficient is about 40% times larger than for fullydeveloped laminar flow in a single packed tube.

573

Reactive Distillation ± A Panacea ora Solution Looking for a Problem?A Case Study Based Evaluation

E . H . S t i t t

Synetix, Billingham, UK

Reactive Distillation is now over 20 years old but has hitherto beencommercially successful in only a limited number of applications.This paper evaluates specifically the potential of reactive distilla-tion for toluene disproportionation by a design and economic com-parison with conventional technology. The ultimate economic eva-luation is equivocal, and the reactive distillation process does notoffer significant benefits. During process development a number ofproblems are encountered and conflicts arise between chemicaland physical requirements, and the needs of process performanceand flowsheet simplicity. This highlights some of the generic pro-blems of reactive distillation and by inference the probably narrowrange of reactions for which it is truly applicable.

574

Coupling of Reaction and Separationat the Microscopic Level: EsterificationProcesses in a H-ZSM-5 MembraneReactor

M . P . B e r n a l

J o a q u õÂ n C o r o n a s

M i g u e l M e n e n d e z

J e s u s S a n t a m a r õ a

Department of Chemical and Environmental Engineering. Facultyof Science. University of Zaragoza, 50009 Zaragoza. Spain. E-mail:iqcatal@posta.unizar.es

The configurations generally used for membrane reactors can beclassified as [1]: reactor + membrane, inert membrane reactorsand catalytic membrane reactors. In this communication we pre-sent the esterification reaction between acetic acid and ethanolin an active zeolite membrane reactor (AZMR). The most commonconfiguration of membrane reactors for esterifications [2] is that inwhich the role of the membrane is limited to the removal of pro-ducts from the reaction environment,thereby increasing the equi-librium conversion. In our case, the zeolite of the membrane is acidZSM-5, i.e., the membrane itself is active for the esterification re-action (usual catalysts are mineral acids, acid resins such as Am-berlyst 15 and Nafion, and acid zeolites as H-ZSM-5). While it ispossible to find in the literature examples of catalytically activepervaporation membranes, such as Nafion used for the esterifica-tion of equilibrium mixtures of acetic acid with methanol and n-butanol [3], to our knowledge this is the first report on the useof catalytic zeolite membranes for this purpose.

767I S M R 2Chemie Ingenieur Technik (73) 6 I 2001