Teaching of Catalysis' V. I. KOMAREWSKY Illinois Institute of Technology, Chicugo, Illinois
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ITH .THE. ADVENT of the second World War, . the v ~ t asign~ficance l of catalysis, long recognized for its many uses in industry, has been sharply emphasized by the multiple demands made upon chemical developments by the armed forces. The production of high explosives, aviation fuel, and synthetic rubber number among the important reasons why the catalytic processes have become a necessary part in the education of the modern student of chemistry. The present situation in the field of catalysis is characterized by a t least three prominent factors. In the first place, catalytic reactions have an extensive and important place both in science and industry; second, the technics employed are difficult ones; and third, very little is understood of the mechanism and underlying theory. It was with realization of these facts that a graduate course in "catalytic reactions and their industrial application" was organized seven years ago a t Illinois Institute of Technology. The purpose of this course was to acquaint the students with the most important catalytic reactions and their industrial application and to teach them to perform the most typical reactions in the laboratory with emphasis on the preparation and handling of catalysts. Through the generous support of industry, the catalytic laboratory acquired a wide variety of equipment such as electrically heated catalytic furnaces, with automatic temperature control, high pressure autoclaves
Because of the lack of a single, generally accepted theory explaining the mechanism of the catalytic action, i t was expedient to adopt the following system in the presentation of the theoretical part of the course. First, the students were taught the experimental facts involved in the particular reaction under discussion. Second, the various existing theories were presented and analyzed.
Third, the experimental worksupporting these theories was studied. Fourth, a general summarization was offered t o which was added the conclusions drawn by the students in the classroom.
Finally, the last few lectures were devoted to a critical survey of the various theoretical approaches to the elucidation of the catalytic action in view of the totalcourse material. That this system war a satisfactowone has been evidenced by the problems for future research often conceived directly during these discussions.
VERTICAI,,E L E C T R I C A L L Y HEArEor
CATALYTIC FURNACE
W"H AmoMATIC TURE AND TROL
TEMPERA-
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The course consisted of 6 hours (2 of lecture and 4 of laboratory) during two semesters, with a credit of 4 semester hours. The average class contained 10 students. Due to time limitations the course was confined to organic catalytic reactions. The introductory lectures classified the material to be presented and defined terms to be used in the course, such as catalysis, catalytic reaction, chemical induction, catalyst, carrier, promoter, and poison. Catalytic reactions were divided into homogeneous (gaseous, molecular, ionic) and heterogeneous, with a short discussion of surface phenomena. The introduction was followed by a brief historical survey, with particular care to select the work which decisively influenced the future development of catalysis and gradually formed the modern conception of catalytic phenomena. The following work of the past was brought to the attention of the stndents: and pumps, high precision distillation column for gases and liquids, Goeckel~as and so on. - - adsorption apparatus,
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1 Paper presented before the Chemical Engineering Division of the Society for the Promotion of Engineering Education. New York, June 29, 1942.
1. Cl6ment and Desormes. Lead chamber process; first catalytic reaction by forming intermediate compounds with the cstalyst. 2. Davy and Dsbbereiner. Contact reactions on platinum. 3. Berzelius. Term "catalysis" and separation of catalytic reactions into a s~ecialbranch of chemistrv.
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4. Mitscherlich. Term "contact catalysis" and emphasis an the importance of contact between catalyst and substrate. 5. Mercer and SchBnhein. Complexity of the mechanism of chemical reaction. 6. Deacon. First catalvtic reaction used as such in industrv. , 7 0 - l r a l d , Gihhs, Rrctlig, Zrlmsky, hlittauh. Halwr Catalytic reactions from rhc slandpoit~t-of thennlrlynarnic*, kinetic., and equilibrium. 8. Sabatier. Catalytic reactions in the presence of metals or metal oxides, and the discovery of hydrogenation. 9. Ipatieff. Specificity of catalyst. promoters and the de. velopment of high-pressure technique. 10. Langmuir, Taylor, and others. Study of catalytic action as related to our modern interpretation of the structure of matter. ~
The study of catalytic reactions started with hydrogenation. There are several reasons for this choice: (1) industrial importance of the reaction; (2) its highly developed technic; (3)' variety of catalyst preparation methods; (4) varying activity of these catalysts, dependent on the preparation method. I n discussing hydrogenation, as well as the subsequent reactions in this course, the following scheme was adhered to: 1. D e f i n i t i o n of terms. 2. D i s c u s s i o n of general chemistry of the reaction. 3. Description of apparatus and procedure used. 4. P r e p a r a t i o n of catalystsand their properties. 5. U s e o f t h e method. 6. Mechanism and theoriesof thereaction. 7. Brief discussion of the industrial applications.
In presenting hydrogenation to the class, hydrogenation proper, hydrogenolysis (destructive hydrogenation), and selective hydrogenation were defined and illustrated. Three methods were discussed :
method. Whereas the latter hydrogenates benzene a t atmospheric pressure, the former requires superatmospheric pressure to accomplish the same reaction. The topic of selective hydrogenation was presented in the light of the recent studies by Adkins, Ipatieff, and an M. I. T. group (Thompson, et al.). The incompleteness of information on this important subject and the necessity of future research work were emphasized. In discussing the mechanism of catalytic hydrogenation the classical theories of Sabatier (hydrides) and I p a t i d (water) were presented. These theories were supplemented by Schmidt's theory of the subject (ions), and by the work of petroleum chemists, such as Twigg, Beeck, and others. The topic of hydrogenation was concluded by discussing the following industrial processes. 1. Hydrogenation of vegetable oils. 2. Hydrogenation of selective polymers (iso-octane production). 3 . Destructive hydrogenation of petroleum products 4. Liouefsction of coal (Bereus Process). 5. Hydrogenation of carbon monoxide and dioxide (FischerTropsch Process).
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DEHYDROGENATION
Dehydrogenation has acquired prime importance during the last few years. Study of this reaction was conducted along the following topics: 1. Dehydrogenation of alcohols to aldehydes and ketones. 2. Dehydrogenation of alicyclic compounds. 3. Dehydrogenation of aliphatic hydrocarbons to olefins and diolefins. 4. Dehvdrocvclization of aliuhatic hvdrocarbons with chain . . Length of six or more carhan atoms ( ~ o l & mProduction) ~
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In discussing dehydrogenations of alicyclic compounds, the classical and extensive work of Zelinsky's school was studied with particular care. Also included were the six-membered carbon ring" rule of Zelinskv. ,. the Balandin multiplet theory, the behavior of the fivecarbon ring compounds, the phenomena of irreversible catalysis. The x-ray and electron ray investigations of Germer, Rupp, Rubinstein were presented to the students. The topics of hydrogenation and dehydrogenaB O M B
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WORKAT ROOM
TEMPERATURES
1. Sabatier's vapor phase method a t high temperature and atmospheric pressure. 2. Ipatieff's high temperature, superatmaspheric pressure method in vapor, liquid and solid phase. 3. The Paal-Skita-Adams colloidal catalyst method at low (rwm) temperature and atmospheric pressure.
Discussion of these methods was supplemented by laboratory work. Students hydrogenated benzene by the Sabatier vapor phase and the Ipatieff high-pressure methods. In this first work, the importance of catalyst activity and its dependence on the method of preparation were clearly illustrated. Students prepared two nickel catalysts, one by the impregnation-ignition method (nickel-asbestos) and two by a precipitation
tion were concluded with discussions of inter- and intramolecular dehydrogenation-hydrogenation using acidic catalysts such as sulfuric or phosphoric acids, aluminum chloride, etc. Laboratory work included: I. Dehydrogenation of alcohol to aldehyde using zinc oxide and copper oxide catalysts. 2. Dehydrogenation of cyclohurane over co-precipitated nickel-aluminacatalyst.
In the last case methods of reactivating the catalyst were discussed and carried out. The industrial dehydrogenations discussed were : 1. Dehydrogenation of gaseous alkanes to olefines (aviation gasoline). 2. Dehydrogenation of olefins to diolrfins (synthetic rubber). 3. Catalytic reforming of gasoline. DRHYDRATION
The following reactions were presented under the topic of dehydration: the reaction of Williamson, dehydration of alcohols to olefins in liquid and in vapor phase, the dehydration of acids, esters, acid amides and aldoximes, simultaneous dehydration, hydrogenation, and dehydrogenation, complex action catalyst, catalysts for dehydration and conditions of the experiments. The laboratory work consisted in preparation of an alumina catalyst by the precipitation method and comparison of its activity with a commercial alumina catalyst in the reaction of dehydration of ethyl alcohol. The chapter was concluded by the discussion of the HMRATION hypotheses of Taylor. I~atieff,and Adaduroff as well as The production of alcohols from olefins, the saponiof A&,& in mechanism of +hydrafication of esters, the inversion of sugar, and the hytion reactions. dration of acetylenes were presented in this chapter.
the
CONDENSATION
The definition of the reaction. Condensation of alcohols with aldehydes and ketones. Condensation of phenols with alcohols, aldehydes, and ammonia. Various condensations with aluminum chloride catalyst. The laboratory work consisted of the preparation of pure aluminum chloride catalyst and the performance of the Friedel-Crafts reaction. ISOMERIZATION
The following reactions were studied: displacement of double and triple bonds, change of the ring structure, change of the chain structure, cis-trans isomerization, metameric isomerization of ethylene oxides. The industrial application of isomerization reactions was illustrated by isomerization of normal butane to iso-butane in the presence of aluminum chloride catalyst. POLYMERIZATION
The definition of the term "polymerization." The organic groups which undergo the polymerization reaction. The following reactions were discussed: polymerization of aldehydes, sugars (work of Pictet), nitriles, unsaturated hydrocarbons. The formation of
natural polymers, synthetic rubber production. The laboratory work consisted in high-pressure polymerization of propene in the presence of phosphoric acid catalyst. The mechanisms of I p a t i d , Berthelot, Monroe, and Gilliland and Whitmore were discussed in connection with this experiment. The reactions of cross polymerization, selective polymerization, bydroand dehydropolymerization, and conjunct polymerization were defined and illustrated. The following industrial processes were presented a t the conclusion of this chapter, both of which lead to the production of high octane motor fuel: 1. Universal Oil Products Company polymerization of olefins in the presence of solid phosphoric acid catalyst. 2. Shell Oil Company polymerization of hutenes in the presence of sulfuric acid catalyst. ALKYLATION
The definition of reactions of alkylation: direct alkylation, alkylation by condensation, destructive alkylation and antodestructive alkylation. Alkylation of aromatic, alicyclic and paraffin hydrocarbons, alkylation of phenols. Catalysts and conditions used. Meehanism and theories. Laborato~ywork included: 1. The alkylation of benzene with ethylene in the presence of aluminum chloride. 2. The alk~lationof benzene with propylene in the presence of sulfuric acid. 3. The alkylation of phenol with iso-butene in the presence of phosphoric acid.
The industrial application of the reaction was illustrated by the sulfuric acid alkylation process for the production of aviation fuel.
oxidation of aromatic compounds (benzene, naphthalene), methods of the Barrett, Monsanto, and Dow Chemical Companies. ADDITION AND ELIMINATION OF HALOGEN, NITROGEN, AND SULFUR-CONTAINING CROUPS
The last few lectures were devoted to the physicochemical study of catalytic reactions. These studies were divided into three groups. 1. Adsorption and its role in catalytic reactions. Various types of adsorption. Capillary condensation. Faust rule. Heats of adsorption. True adsorption, its importance in cataIvtic reaction. Lanemuir's work. monomolecular laver. Varietv of the phenomena on the surface of a catalyst. 2. Kinetic studies of catalytic reactions. Intermediate compound formation. Energy' of activation. Elucidation of reaction mechanism from kinetic measurements. 3. Studies of catalytic phenomena from the point of matter structure. Activation of the surface. Poisonina of the surface. active centers, mixed catalyst. Role of carriers-and promoters: The geometry of catalytic surface. Catalytic activity and particle size. Orientation of crystals. General conclusions. BOOKS
Although various selected chapters of the following books2 were recommended to students in the presentation of this course, the major part of the studies must be based on the original literature. General: "Catalysis in organic chemistry," Van Nos1. SABATIER. trand, New York, 1923. 2. RrDeAL AND TAYLOR. "Catalysis in theory and practice," Macmillan and Company, London. 1926. 3. IpATmPa, "Catalytic reactions a t high pressures and temperatures." The Macmillan Company, New York, 1936. 4. BEREMAN,MORREL,AND EGLOFP,"Catalysis, inorganic and organic," Reinhold Publishing Company, New York. 1940. Hydrogenation:
5. MAXTED, "Catalytic hydrogenation and reduction," London. 1919. 6. ELLIS,"Hydrogenation of organic substances." Van Nostrand, New York. 1930. 7. A D ~ N S "Reactions , of hydrogen," The University of Wisconsin Press, Madison, Wisconsin. 1937. Dehydrogenation and Oxidation: 8. MAREK."The catalytic oxidation of organic compounds in vapor phase," Chemical Catalog Company, New York, 1932. Polymerization: 9. B m x , THOM~ON, WEITHAND. W n L I m s , "Pdymerization and its application in the field of rubber, synthetic resins, and petroleum," Reinhold Publishing Company, New Yark, 1937. Isomerization:
OXIDATION The following types were discussed: oxidation of carbon monoxide by oxygen and by water, oxidation of paraffin hydrocarbons, oxidation of methane to formaldehyde, oxidation of methane to carbon monoxide and hydrogen, oxidation of higher paraffins to acids, oxidation of alcohols (methyl, ethyl, and isopropyl),
"Isomerization of 10. Ecmaa, HULLA, AND KOMAREWSKY, pure hyrlrmarbons," Reinhold Publishing Company, New York. 1942.
Alkylation, Condensation and Other Reactions: 11. THOMAS."Anhydrous aluminum chloride," Reinhold Publishing Company, New York, 1941. 1 Only hooks in the English language are presented in this list.
Theory and Mechanism: 12. SCHWAB, ''Catalysis from the standpoint of chemical kinetics," Van Nostrand, New York, 1937. 13. Nunop, "The catalytic action of surfaces," Williams and Norgate, Ltd., London, 1937. 14. GWPPITHS, "The mechanism of contact catalysis," Oxford University Press, Cambridge, 1936. 15. BBLL,"Acid-Base catalysis," Oxford Clarendon Press, Cambridge, 1941.
Industrial Applications of Catalysis:
16. GREEN,"Industrial catalysis," E Bcnn., Ltd., London 1928.
17. HENDERsoN. "Catalysis in industrial chemistry," Langmans Green and Co.. London, 1919. 18. HILDICH. "Catalytic processes in applied chemistry." Chapman and Hall, Ltd., London, 1937. 19. See also "The twelfth report of the committee on catalysis. National Research Council," Wiley and Sons, New York. 1940.
