Overview on the Department of Industrial Chemistry IUniversity of Oldenburg

Prof. Dr. Jürgen Gmehling

The Chair of Industrial Chemistry is part of theChemistry Department. Apart from different spe-cial courses the main fields of teaching are:Introduction to Chemical Engineering, ChemicalReaction Engineering, Unit Operations andChemical Processes. The main research activi-ties are directed towards the synthesis anddesign of thermal separation processes andheterogeneous catalysis. This includes:

• development of reliable thermodynamicmodels (gE-models, equations of state,group contribution methods) for the predic-tion of phase equilibria, excess propertiesand pure component properties.

• development of computerized devices forthe determination of physical properties.

• measurement of phase equilibria, heats ofmixing, pure component properties andreaction rates.

• development of software tools for the syn-thesis and design of separation processesand development of new computerizeddata bases.

• experimental investigations involving va-rious unit operations (reactive distillation,adsorption, membrane processes, separa-tion of enantiomers...) and application ofblah

thermodynamic models to process devel-opment, environmental protection, biotech-nology and labor safety.

• heterogeneous catalysis using ion ex-change resigns

Many of the experimental facilities are operatedby the associated institute LTP GmbH (Labo-ratory for Thermophysical Properties).

In addition there is a close cooperation withDDBST GmbH, Oldenburg, a company whichengages in the update of thermodynamic data-bases (DDB) and the development of softwarepackages (DDBSP).One of the long-term activities of the groupdeals with the development or further devel-opment of group contribution methods for thedescription of the real behavior of purecomponents and mixtures. Well known modelslike mod. UNIFAC, PSRK and LIFAC originatefrom this group and are constantly improved.These models are used for process simulationby thousands of engineers worldwide.The Department of Industrial Chemistry offersa variety of different courses for studentshaving finished the intermediate tests after thesecond year of study as well as special con-tinued education courses for external partici-pants (in collaboration with GVT, DECHEMA,Aspen Tech, chemical industry).

For further information please contact:Prof. Dr. J. Gmehling, University of OldenburgDepartment of Industrial Chemistry, FB9P.O.Box 2503 , D-26111 OldenburgPhone: +49 441 7983831 , Fax: +49 441 7983330Email: gmehling@tech.chem.uni-oldenburg.de

Different Recycle Reactors ( internal loop)In different recycle reactors developed in our group( internal loop - see figure 3 and 4 - as well as externalloop ), we studied the activity of the catalytic packings.A number of experiments ( using an acrylic glass-copy ofthe reactor ) gave the optimal mixing equipment. Usinga pitched-bladed axial flow turbine above and a 2-bladeddiagonal flow impeller below the packing, a stirring rate of650 rpm allows for a mean residence time of less thanone second in the packing.Catalytic activity was determined with hydrogenation andoxidation reactions. Reactions of interests were:• the catalytic removal of dissolved oxygen from water• the hydrogenation of 1-tetradecene and toluene.

The reduction of Oxygen dissolved in Water served as amodel reaction. With the aid of a fluidized bed reactor thereaction kinetic is limited by external mass transferresistance even if the Palladium loading is smaller 0.6 %<5>.The catalytic activity of the structured packing is limitedby external mass transfer resistance even if the Palladiumloading is smaller than 2.5 %. Compared to the aid of afluidized bed reactor, the Palladium loading can beincreased by a factor of 4 without diffusional limitation inthe external film.

References1 „Katalysatoren für heterogene Systeme”, J.-P. Stringaro, J. Luder, chemie - anlagen +

verfahren, 4, 19922 „Controlled growth of thin films of molecular sieves on various supports”, J.C. Jansen, W.

Nugroho, H. van Bekkum, Proc. 9th Int. Zeolite Conf., Montreal, p. 247, 19923 „Preparation of ZSM-5 Zeolite Film on metal support“, A. Brehm*, U. Antons, A. Bekurdts, in

“Reaction kinetics and the development of catalytic processes”, G.F. Froment, K.C. Waugh;Studies in Surface Science and Catalysis, Vol. 122, S.451, 1999

4 „Preliminary studies on the synthesis of alkaline-free large crystals of ZSM-5”, U. Müller,K.K. Unger, ZEOLITES, 8, 154 (1988)

5 Zur Reduktion von in Wasser gelöstem Sauerstoff unter Verwendung einesFließbettreaktors” , A. Brehm, U. Antons, Chem.-Ing.-Tech., 70, S.176-181 (1998)

Differential Recycle Reactors mounted withZeolite-covered Structured Packing

Prof. Dr. Axel Brehm

IntroductionTo improve the hydrodynamic aspects (heat and masstransfer, pressure drop and uniformity of distribution)Sulzer Chemtech Ltd. developed open crossflow channelcatalysts and catalyst supports based on the well knownstructured packing concept <1>. The preparation of thinfilmed molecular sieves (MFI-types) on various supports isdescribed (Jansen et al. <2>). In our lab ZSM-5 cover hasbeen produced by the in situ crystallization on structuredpackings as supports <3>. Here the preparation of ZSM-5zeolite was based on the alkaline-free synthesis (Müllerand Unger <4>) using wire supports ( e.g. Sulzer-packings) included in the hydrogel.

Characterization of ZSM- zeolite film• X-ray diffraction was used to check the zeolite type.• Micrographs and scanning electron micrographs

(SEM) showed several aspects of the crystallization,especially the habit, size, orientation and degree ofcoverage.

• Thermic stability was shown via repeated shock-cooling from 773 K to 273 K. This operation did notresult in a significant loss of zeolite material andfacilitated the calcination of the zeolite films.

• Mechanical scratch techniques demonstrated thestability of the crystal on the substrate ( figure 1 ).

• Figure 2 shows the back of the zeolite film. Thesample was prepared by dissolving the metal substratewith HCl.

• EDX-spectroscopy was used to determine theplatinum- and palladium-dispersion ( as the catalyticactive metals ).

figure 1: Zeolite Film afterMechanical Scratch with aSharp Spatula

figure 2: Back of ZSM-5 FilmThe sample was prepared by dis-solving the metal-substrate usingHCl.

figure 3 : Different Recycle Reactors( internal loop)a) arrest structured packingb) sketch of Reactor

For further informations please contact

Prof. Dr. Axel Brehm, University of Oldenburg, FB 9P.O.Box 2503, D-26111 OldenburgPhone: +49 441 798 3841; Fax: +49 441 798 3330Email: brehm@tech.chem.uni-oldenburg.de