Ind. Eng. Chem. Res. 1997, 36, 2877-2881
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Gilbert F. Froment Gilbert Froment has put his mark on the reaction engineering community around the world, as editor of Chemical Engineering Science, as one of the founders of the ISCRE symposium series, as a teacher, as a researcher, as a consultant, and as an author. His research activities cover the classical reaction engineering range: thermal reactions, heterogeneously catalyzed reactions, kinetics, and all forms of chemical reactors. Some of his contributions in these areas were of a seminal nature and all of them were grounded in his fundamental approach of industrially significant problems. Gilbert Froment has been building bridges during his career, between academia and industry, between the European countries, between Europe and the U.S., and between Europe and South America and Asia. He was very successful in his endeavors, and his achievements will continue to bear fruit for the chemical engineering community. It is our privilege and pleasure to dedicate this festschrift issue of Industrial and Engineering Chemistry Research to Gilbert F. Froment. We are very grateful to the Editor of Ind. Eng. Chem. Res., Donald R. Paul, for his enthusiastic support for this effort and to all the authors who have responded in such a generous way to present their best work to honor Gilbert Froment. Gilbert Froment received his chemical engineering degree from the University of Gent in 1953. His graduate education took place at the same university, where he was employed as an assistant of Professor Goethals, who was also his advisor. Gilbert earned his doctoral degree in chemical engineering in 1957. The next two years were the start of his international focus. He spent first a year in Darmstadt with Professor Schoenemann at the Institut fu¨r Chemische Technologie der Technischen Hochschule Darmstadt. Professor Schoenemann was a pioneer of the introduction of Chemical Engineering in Germany. His industrial experience with BASF and broad outlook on the chemical industry, past and present, was extremely stimulating for a young man like Gilbert, who also closely cooperated with Hanns Hofmann, who was a Privat Dozent at the Institut and later became Professor of Chemical Engineering at the University of ErlangenNu¨rnberg. The next year Gilbert Froment obtained an Advanced CRB-Fellow from the Belgian American Educational Foundation and the Francqui Foundation and went to the University of Wisconsin, where he worked with Professors O. A. Hougen and K. M. Watson on catalytic kinetics and with Professor C. C. Watson on the modeling of the regeneration of coked catalyst beds. S0888-5885(97)00298-4 CCC: $14.00
Those were also the days when Bird, Stewart, and Lightfoot tried out their “Notes on Transport Phenomena” and Gilbert was impressed by their rigor, thoroughness, and elegance. Darmstadt and Madison were the foundation of Gilbert’s fundamental approach to industrial processes, which became his trademark. Froment returned to Gent to start his academic career. He moved swiftly through the ranks and became chair professor in 1969. The year before he founded the Laboratorium voor Petrochemische Techniek, of which he became the director. Since then he has built this “laboratorium” into a world class outfit, which has set a standard in the chemical reaction engineering community. Froment is an outstanding teacher, which brought him all over the world. He has been a visiting professor at other Belgian universities, Katholieke Universiteit Leuven (1967-77) and Universite Libre de Bruxelles (1967-69), and at Yale University (1969), University of Houston (1973 and 1981), Universidad Nacional del Sur, Bahia Blanca, Argentina (1977), University of Buenos Aires, Argentina (1981), Universidad de Salta (since 1983), University of Santa Fe, Argentina (1983), and University of Stanford (1984). He also was an Adjunct Professor at University of Delaware (1980-85). © 1997 American Chemical Society
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Figure 1. Aspects to be dealt with in the modeling of fixed-bed reactors. Reprinted with permission from John Wiley & Sons, Inc. Copyright 1979, 1990 John Wiley & Sons, Inc.
Figure 2. Classification of fixed-bed reactor models. Reprinted with permission from John Wiley & Sons, Inc. Copyright 1979, 1990 John Wiley & Sons, Inc.
Froment’s objective has been from the very start of his career to design or simulate industrial catalytic reactors using mathematical models, based on sound theoretical background and adequate experimentation. His work and vision are probably best characterized by two figures from his book Chemical Reactor Analysis and Design (2nd ed., 1990), which is used in many universities around the world. Figure 1 (1990) splits the problems encountered in catalytic reactor design and simulation into two main levels: the micro- and macrolevel. The microlevel comprises the active sites and the catalyst particle and the macrolevel the bed of catalyst particles. The active sites part of the microlevel deals with the nature of the sites, their interaction with neighboring sites and the gas phase, their activity, and their deactivation. This is the broad area of catalytic chemical kinetics in which Froment has contributed continuously and with great authority from the beginning in developing more mechanistic, and therefore more realistic models, involving more and more the detailed transformations of both the fluid molecules and the catalytic surface. Most of the active sites are located inside the catalyst particle, so that mass and heat transfer between the fluid phase and the catalyst, as well as that inside the catalyst, have to be considered. The most difficult problem relates to the transport inside the particle, and this has actively been addressed by Froment since the 1980s when the catalyst particle was still dealt with as a single pore or at best as a pseudocontinuum. Froment was aware of the need to retain the network topology on the modeling, in particular when pores can be
blocked by metals or coke deposition. This led him to apply, at the forefront of the development, Bethe and percolation networks to the description of mass transport and reaction inside catalyst particles, instead of the description in terms of a tortuosity factor. Recently he introduced the morphology of the pore wall, eventually fractal, in the simulation of industrial processes and showed it to be of considerable influence on the conversion and selectivities. The macrolevel, as shown in Figure 1, is the reactor level. What has to be considered here in the mathematical modeling is fluid flow, heat transfer, and momentum transfer. In 1971 already Froment published a classification of fixed-bed reactor models, which is accepted worldwide and is shown in Figure 2 (1990), also taken from the above-mentioned book. In these days he developed sophisticated heat-transfer models for packed-bed operation. In the 1980s and 1990s he introduced nonuniform velocity profiles in the modeling, thus approaching more and more a three-dimensional model of a packed-bed reactor, which is now in reach. Froment has been a pioneer in the rationalization and modeling of catalyst deactivation by coke formation. He studied this phenomenon on the three levels mentioned above: the active site (or clusters thereof), the particle (a network of pores that can be blocked by coke), and the reactor. He applied the theory to industrial processes and real catalysts and developed specific equipment, like the electrobalance with recycle, for adequate and accurate experimentation. Another major area where Froment has been active is thermal cracking for olefins production, an operation
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of tremendous industrial importance, providing the key building blocks for the petrochemical and chemical industries. Froment started research in this area already in 1959, stressing the derivation of accurate kinetic data from experimentation in tubular flow reactors and developing the equivalent reactor volume concept introduced by Hougen and Watson. Between 1971 and 1973 he designed and built a computercontrolled pilot unit for thermal cracking, which was continuously adapted and still is one of a kind in the world. The pilot plant has provided data over a wide range of feedstocks, from light hydrocarbons and their mixtures to vacuum gas oil. These experimental data were the basis for extensive kinetic modeling developed from rigorous radical mechanisms, using transitionstate chemistry to guide parameter estimation and ranging from the cracking of light hydrocarbons mixtures to the cracking of vacuum gas oil. The reaction network for the cracking of heavy components and mixtures thereof, like naphtha and gas oil, is extremely complex. This is why Froment developed, starting from the basic radical mechanisms and graph theory, the computer generation of such networks. Froment tackled not only the kinetics but also the reactor modeling. He not only developed two- and three-dimensional models for the simulation of high-severity cracking coils but also modeled the firebox in which the cracking coils are heated. This combined simulation of coil and furnace requires discretization of the furnace volume and walls and of the coils into a set of interconnected isothermal zones. This impressive effort, combining heat transfer and three-dimensional computational fluid dynamics calculations, led to the most advanced furnace model in use today. Some 15 years ago the Laboratorium voor Petrochemische Techniek was awarded the status of Center of Excellence by the Belgian Ministry of Science for its research in catalytic reaction engineering. The associated funding boosted the equipment of the Lab and permitted the acquisition of the TAP-reactor, SEM, FTIR equipment with built-in reactor cell and on-line GCMS, on-line Mo¨ssbauer equipment, and powerful computers. The number of industrial processes that Froment investigated both from the kinetics and reactor design point of view increased and reached from steam reforming and catalytic partial oxidation for synthesis gas production, methanol synthesis (also by reverse-flow operation), Fischer-Tropsch synthesis, methanol to olefins, ethylbenzene dehydrogenation, catalytic oxidation of o-xylene into phthalic anhydride and of propylene into acrolein, and most of the petroleum conversion processes. Certain wines improve upon aging and so do certain scientists. In recent years Froment achieved breakthroughs in the kinetic modeling of complex catalytic processes, which are presently being applied in the research centers of the large oil companies. Until recently the catalytic reforming of naphtha and the catalytic cracking and hydrocracking of vacuum gas oil on acid catalysts loaded or not with metals were modeled in terms of lumps. Froment turned instead to the modeling of kinetics in terms of the individual components. Dealing with those on the molecular level would require an unrealistic number of rate coefficients, but expressing the transformations in terms of elementary steps and single events of carbenium ion chemistry (in very much the same way as he expressed the thermal cracking in terms of radical mechanisms)
allowed Froment to reduce this number to a tractable set. A similar approach was used in hydrodesulfurization, where Froment introduced the “structural contribution” approach, as opposed to the gross lumping of the sulfur components in use to date. Again considering the transformation of the individual S-containing components on the molecular level would lead to an overwhelming number of rate parameters. Instead, Froment related the rates of the substituted S-components to that of the unsubstituted parent molecule by the introduction of electronic and steric hindrance effects exerted by the substituent groups. This development called for accurate kinetic experiments on model components and complex mixtures, besides quantum chemical calculations. Froment has been the advisor of some 50 Ph.D. theses, and numerous visiting scientists have spent fruitful periods in Gent. Many of his students occupy important positions in industry, universities, and government in Belgium and abroad. They, together with Froment’s scientific contributions, form Gilbert’s legacy to the chemical reaction engineering community. Gilbert Froment is also very active in professional organizations. He is the founder of the Chemical Engineering Section of the Koninklijke Vlaamse Ingenieursvereniging and a member of the Working Party on Chemical Reaction Engineering of the European Federation of Chemical Engineering since 1966 and of the Working Party of the Use of Computers in Chemical Engineering since 1968. He has organized many congresses such as those on “Catalyst Deactivation” and “Large Chemical Plants”. He recently chaired ISCRE14 in Bruges, Belgium. Froment has also been very active as an editor. He was co-editor of Chemical Engineering Science from 1965 until 1996 and of Chemical Reaction Engineering Reviews since 1971 and is or was a member of the editorial boards of Bulletin des Societes Chimiques Belges, Applied Catalysis, Industrial and Engineering Chemistry, Chemical Engineering Reviews, Revista Latino-Americana de Ingenieria Quimica, and Energie Primaire. Froment has been widely recognized, in Belgium and abroad, for his role as an educator and a scientist. He has received the Frederick Swarts Award for Applied Chemistry of the Royal Belgian Academy (1958), the National Alumni Award of the Belgian University Foundation (1966), the Prix Cornez de la Province du Hainaut (1976), and the R. H. Wilhelm Award in Chemical Reaction Engineering from the American Institute of Chemical Engineers (1984). He received a Doctor of Science Honoris Causa degree from Technion, Haifa, Israel (1984), and was elected a member of the Acade´mie Royale Belge des Sciences d’Outremer in 1981 and a member of the Koninklijke Academie van Belgie, Class of Science, in 1988. Behind every strong man is a strong woman! Mia has been that stronghold that allowed Gilbert to roam the world and work constantly. All Gilbert’s students, collaborators, and colleagues have enjoyed the warm hospitality of their home. Mia’s culinary achievements could easily compete with Gilbert’s scientific contributions. Mia and Gilbert are complementary in many ways, but it should be highlighted that Mia, who is a mathematician, encouraged Gilbert in his work, in the same fashion that Gilbert’s knowledge of wines helped Mia’s cuisine reach the top. Gilbert has also many interests: sports and culture top the list. Gilbert played competition soccer and kept playing for many years in
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intramural competition at the University. Now, after a few broken legs, he has become an avid cyclist, taking long flings through his favorite countryside. Before taking up cycling, he owned and rode beautiful horses. Last but not least we have to mention that he is also an avid hunter. Mia and Gilbert share a passion for antiques, which led to an exceptional collection of antique paintings, furniture, statues, and tapestries. This festschrift was conceived during the organization of “A Tribute to Prof. Dr. ir. Gilbert Froment”, a full day celebration we organized last year to celebrate Gilbert’s 65th birthday. Gilbert, now professor emeritus, shows no signs of slowing down; on the contrary, he is more active than ever in research, generating new research projects, organizing meetings, consulting, and teaching all over the world. His list of recent publications provides an illustration of Froment’s productivity, creativity, diversity, and depth. Recent Publications of Prof. Froment Schools, E. M.; Froment, G. F. Simulation of decoking of thermal cracking coils by steam/air mixtures. AIChE J. 1996, 43, 118. Coppens, M.-O.; Froment, G. F. Catalyst design accounting for the fractal surface morphology. Chem. Eng. J. (Lausanne) 1996, 64, 69. Froment, G. F. A fundamental approach for technological developments in ethylene production. AIChE Proc.sEthylene Prod. Conf. 1996, 5, 597. De Groote, A. M.; Froment, G. F. Synthesis gas production from natural gas in a fixed-bed reactor with reversed flow. Can. J. Chem. Eng. 1996, 74, 735. Vanden Bussche, K. M.; Froment, G. F. The STAR configuration for methanol synthesis in reversed flow reactors. Can. J. Chem. Eng. 1996, 74, 729. Al-Fadli, A. M.; Soliman, M. A.; Froment, G. F. Steady state simulation of a multi-bed adiabatic reactor for methanol production. J. King Saud Univ., Eng. Sci. 1995, 7, 101. Vanrysselberghe, V.; Froment, G. F. Hydrodesulfurization of Dibenzothiophene on a CoMo/Al2O3 Catalyst: Reaction Network and Kinetics. Ind. Eng. Chem. Res. 1996, 35, 3311. Vanden Bussche, K. M.; Froment, G. F. A steady-state kinetic model for methanol synthesis and the water gas shift reaction on a commercial Cu/ZnO/Al2O3 catalyst. J. Catal. 1996, 161, 1. Devriendt, K.; Poelman, H.; Fiermans, L.; Creten, G.; Froment, G. F. Angular resolved XPS applied to V2O5-based catalysts. Surf. Sci. 1996, 352, 750. Papageorgiou, J. N.; Froment, G. F. Phthalic anhydride synthesis. Reactor optimization aspects. Chem. Eng. Sci. 1996, 51, 2091. De Groote, A. M.; Froment, G. F. Simulation of the catalytic partial oxidation of methane to synthesis gas. Appl. Catal., A 1996, 138, 245. Wang, D.; Dewaele, O.; De Groote, A. M.; Froment, G. F. Reaction mechanism and role of the support in the partial oxidation of methane on Rh/Al2O3. J. Catal. 1996, 159, 418. Coppens, M.-O.; Froment, G. F. Fractal aspects in the catalytic reforming of naphtha. Chem. Eng. Sci. 1996, 51, 2283. Heynderickx, G. J.; Froment, G. F. A Pyrolysis Furnace with Reactor Tubes of Elliptical Cross Section. Ind. Eng. Chem. Res. 1996, 35, 2183. Souverijns, W.; Parton, R.; Martens, J. A.; Froment, G. F.; Jacobs, P. A. Mechanism of the paring reaction of naphthenes. Catal. Lett. 1996, 37, 207. Delmon, B.; Froment, G. F. Remote control of catalytic sites by spillover species: a chemical reaction engineering approach. Catal. Rev.sSci. Eng. 1996, 38, 69. Wang, X. L.; Gomez, M. F.; De Saegher, J. J.; Froment, G. F.; Woerde, H. M. Thermal cracking of isobutane at high pressure. Erdoel, Erdgas, Kohle 1996, 112, 28. Froment, G. F. Catalytic reaction engineering is analyzed and illustrated at three levels: micro, meso and macro. Entropie 1995, 31, 10. Creten, G.; Lafyatis, D. S.; Froment, G. F. Transient kinetics from the TAP reactor system: application to the oxidation of propylene to acrolein. J. Catal. 1995, 154, 151.
Svoboda, G. D.; Vynckier, E.; Debrabandere, B.; Froment, G. F. Single-Event Rate Parameters for Paraffin Hydrocracking on a Pt/US-Y Zeolite. Ind. Eng. Chem. Res. 1995, 34, 3793. Papageorgiou, J. N.; Froment, G. F. Simulation models accounting for radial voidage profiles in fixed-bed reactors. Chem. Eng. Sci. 1995, 50, 3043. Beirnaert, H. C.; Vermeulen, R.; Froment, G. F. A recycle electrobalance reactor for the study of catalyst deactivation by coke formation. Stud. Surf. Sci. Catal. 1994, 88, 97. Reyniers, M.-F. S. G.; Froment, G. F. The influence of metal surface and sulfur addition on coke deposition in the thermal cracking of hydrocarbons. Proc.sEthylene Prod. Conf. 1994, 3, 652. De Groote, A. M.; Froment, G. F. Reactor modeling and simulations in synthesis gas production. Rev. Chem. Eng. 1995, 11, 145. Coppens, M.-O.; Froment, G. F. Diffusion and reaction in a fractal catalyst poresI. Geometrical aspects. Chem. Eng. Sci. 1995, 50, 1013. Coppens, M.-O.; Froment, G. F. Diffusion and reaction in a fractal catalyst poresII. Diffusion and first-order reaction. Chem. Eng. Sci. 1995, 50, 1027. Coppens, M.-O.; Froment, G. F. Diffusion and reaction in a fractal catalyst poresIII. Application to the simulation of vinyl acetate production from ethylene. Chem. Eng. Sci. 1994, 49, 4897. Reyniers, M.-F. S. G.; Froment, G. F. Influence of Metal Surface and Sulfur Addition on Coke Deposition in the Thermal Cracking of Hydrocarbons. Ind. Eng. Chem. Res. 1995, 34, 773. Bailey, S.; Froment, G. F.; Snoeck, J. W.; Waugh, K. C. A DRIFTS study of the morphology and surface adsorbate composition of an operating methanol synthesis catalyst. Catal. Lett. 1995, 30, 99. Papageorgiou, J. N.; Abello, M. C.; Froment, G. F. Kinetic modeling of the catalytic oxidation of o-xylene over an industrial V2O5TiO2 (anatase) catalyst. Appl. Catal., A 1994, 120, 17. Pille, R. C.; Yu, C.-y.; Froment, G. F. Kinetic study of the hydrogen sulfide effect in the conversion of thiophene on supported CoMo catalysts. J. Mol. Catal. 1994, 94, 369. Lafyatis, D. S.; Creten, G.; Froment, G. F. TAP reactor study of the partial oxidation of methanol to formaldehyde using an industrial Fe-Cr-Mo oxide catalyst. Appl. Catal., A 1994, 120, 85. Froment, G. F.; Depauw, G. A.; Vanrysselberghe, V. Kinetic Modeling and Reactor Simulation in Hydrodesulfurization of Oil Fractions. Ind. Eng. Chem. Res. 1994, 33, 2975. Reyniers, G. C.; Froment, G. F.; Kopinke, F.-D.; Zimmermann, G. Coke Formation in the Thermal Cracking of Hydrocarbons. 4. Modeling of Coke Formation in Naphtha Cracking. Ind. Eng. Chem. Res. 1994, 33, 2584. Gottifredi, J. C.; Gonzo, E. E.; Froment, G. Diffusion and reaction inside a catalyst pellet for a parallel-consecutive reaction scheme. Chem. Eng. Sci. 1994, 49, 2399. Lafyatis, D. S.; Froment, G. F.; Pasau-Claerbout, A.; Derouane, E. G. A TAP reactor investigation of C6 reforming on nonacidic and acidic supported metal catalysts. J. Catal. 1994, 147, 552. Vanden Bussche, K. M.; Froment, G. F. Nature of formate in methanol synthesis on Cu/ZnO/Al2O3. Appl. Catal., A 1994, 112, 37. Froment, G. F. Transient operation of fixed bed catalytic reactors; Weijnen, M. P. C., Drinkenburg, A. A. H., Eds.; PU-Kluwer: Dordrecht, The Netherlands, 1993; Vol. 1, p 437. Kopinke, F. D.; Zimmermann, G.; Reyniers, G. C.; Froment, G. F. Relative rates of coke formation from hydrocarbons in steam cracking of naphtha. Aromatic hydrocarbons. Ind. Eng. Chem. Res. 1993, 32, 2620. Feng, W.; Vynckier, E.; Froment, G. F. Single event kinetics of catalytic cracking. Ind. Eng. Chem. Res. 1993, 32, 2997. Vanden Bussche, K. M.; Neophytides, S. N.; Zolotarskii, I. A.; Froment, G. F. Modeling and simulation of the reversed flow operation of a fixed-bed reactor for methanol synthesis. Chem. Eng. Sci. 1993, 48, 3335. Froment, G. F. Kinetic modeling of complex processes. Thermal cracking and catalytic hydrocracking. Chemical Reactor Technology for Environmentally Safe Reactors and Products; NATO Advanced Study Institute Series E225; Plenum: New York, 1993; p 409. Martens, J. A.; Uytterhoeven, L.; Jacobs, P. A.; Froment, G. F. Isomerization of long-chain n-alkanes on platinum/HZSM 22 and Pt/HY zeolite catalysts and on their intimate mixtures. Stud. Surf. Sci. Catal. 1993, 75, 2829.
Ind. Eng. Chem. Res., Vol. 36, No. 8, 1997 2881 Marchi, A. J.; Froment, G. F. Catalytic conversion of methanol into light alkenes on mordenite-like zeolites. Appl. Catal., A 1993, 94, 91. Lox, E. S.; Froment, G. F. Kinetics of the Fischer-Tropsch reaction on a precipitated promoted iron catalyst. 2. Kinetic modeling. Ind. Eng. Chem. Res. 1993, 32, 71. Beyne, A. O. E.; Froment, G. F. A percolation approach for the modeling of deactivation of zeolite catalysts by coke formation: diffusional limitations and finite rate of coke growth. Chem. Eng. Sci. 1993, 48, 503. Kopinke, F. D.; Zimmermann, G.; Reyniers, G. C.; Froment, G. F. Relative rates of coke formation from hydrocarbons in steam cracking of naphtha. 2. Paraffins, naphthenes, mono-, di-, and cycloolefins, and acetylenes. Ind. Eng. Chem. Res. 1993, 32, 56.
Lox, E. S.; Froment, G. F. Kinetics of the Fischer-Tropsch reaction on a precipitated promoted iron catalyst. 1. Experimental procedure and results. Ind. Eng. Chem. Res. 1993, 32, 61. Jan J. Lerou* DuPont Central Research & Development, Experimental Station, Wilmington, Delaware 19880-0304 Guy B. Marin Laboratorium voor Petrochemische Techniek, Universiteit Gent, Krijgslaan 281, B-9000 Gent, Belgium
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