In the Classroom
Advanced Chemistry Classroom and Laboratory
edited by
Joseph J. BelBruno Dartmouth College Hanover, NH 03755
Industrial Applications of Inorganic Chemistry: A Junior–Senior-Level Interdisciplinary Course Lidia M. Vallarino* Department of Chemistry, Virginia Commonwealth University, Richmond, VA 23284-2006;
[email protected] Gary E. Wnek Department of Chemical Engineering, Virginia Commonwealth University, Richmond, VA 23284-3068
The Committee on Professional Training of the American Chemical Society stated in a recent publication, “Chemistry pervades our modern social and economic life. All chemists, including those whose interests focus strongly on research, can benefit from an understanding of economics, marketing, and the environment” (1). In agreement with this statement and in response to a widespread awareness that most chemistry and chemical engineering graduates enter the professional arena well prepared in the theory of their subjects but with little knowledge of the all-important industrial applications and their relevance to society, a number of institutions have introduced aspects of industrial chemistry into the undergraduate curriculum. Courses have been developed to “bring the chemical industry into the classroom” at various levels (2) and both textbooks and reference books have been published (3). A survey of these courses and the undergraduate-level textbooks finds the greatest emphasis on the environmental impact of the chemical industry and on the industrial aspects of organic and polymer chemistry. In contrast, the large-scale industrial processes of inorganic chemistry, on which our society depends for most of its essential needs (five of the “top-ten” chemicals produced in the USA are inorganic) (4), have received minimal attention. We report here the development of an innovative lecture and laboratory course, Industrial Applications of Inorganic Chemistry, offered for the first time in 1999 at Virginia Commonwealth University as part of an interdisciplinary program in which chemistry and chemical engineering students learn both fundamental concepts and their practical applications. Also part of this program are Materials Chemistry I & II, a two-semester freshman chemistry course introduced in the fall of 1997, and a two-semester sophomore-level organic chemistry course that focuses on industrial processes. The theme of these courses, which are team-taught by faculty of the departments of Chemistry and Chemical Engineering, is the merging of the world of the microscopic (atoms and ions, bonding, molecular structure) with the world of the macroscopic (materials, properties, process technology, applications). The students learn from examples how creative ideas and scientific research are the basis for the design and development of the industrial processes that provide society with the commodities it needs, and how in turn societal needs provide the stimulus for new ideas and further research.
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The Lecture Course
Objectives Our goal is to equip the students not only with a sound understanding of the topics considered in the lectures, but also with an appreciation for the impact of the inorganic chemical industry on society and the economy. The relationship between inorganic chemistry and human progress can be traced to ancient times, and the “ages” based on stone, iron, and bronze are examples of early chemical industries. Objectives are to (i) relate the fundamental principles of inorganic chemistry to the technology of industrial processes, (ii) illustrate the role of the inorganic chemical industry in the global economy, (iii) explore the principles of materials by design, (iv) discuss the environmental issues related to the inorganic chemical industry, and (v) provide a concrete view of the material presented in lectures through visits to local chemical industries. Within the general educational approach outlined, Industrial Applications of Inorganic Chemistry fulfills the role of capstone course, in bringing together many previously learned concepts to provide a rational pattern for the largestscale industrial processes that support our civilization. Content Part I The major part of the course constitutes a set of modules, each of which deals with a large-scale inorganic industrial process. All modules follow the same general pattern, with appropriate adaptations to each subject, and consider the following: 1. Physical and chemical properties of the product, and correlation of the properties to chemical structure and bonding. 2. Major uses, and correlation of uses to properties. Summary of the economic significance of the product. 3. Outline of the chemical reaction, or sequence of reactions, by which the product can be manufactured on a large scale. Identification of the “starting materials” and discussion of their abundance, geographic location, and production from natural sources. 4. Industrial process(es) by which the product is currently obtained: operating conditions, energy and material balances, yields.
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In the Classroom 5. Potential health and environmental hazards arising from the process and measures adopted to prevent or at least minimize them. 6. Overview of the economics of the process (introducing the “$” into chemical equations).
In the discussion of all industrial processes, the thermodynamic and kinetic aspects of the chemical reactions serve to rationalize the choice of operating conditions in terms of temperature and pressure, and catalysts when required. Each process is illustrated with plant diagrams to show the flow of materials and energy; in the future, we plan to supplement these visual aids with photographs and video presentations. When different processes are in use for any one product, their respective advantages and disadvantages are critically discussed. Since chemistry students have had no previous exposure to the technical aspects of chemical plants, a series of supplementary sessions is scheduled early in the course to provide the necessary background on types of reactors, heat exchangers, filters, pumps, and other equipment. The contents and order of presentation of the modules is given below. Energy, Air, and Water. This module introduces the three requirements of all chemical industry. Energy sources (fossil fuels, renewable biomass, geothermal, solar, wind, water flow and tides, nuclear) are discussed and compared in terms of availability, mode and convenience of use, cost, and environmental considerations. Particular attention is given to the production of electrical energy from nuclear reactors and to the long-term management of nuclear waste. The role of air as a source of oxygen, nitrogen, and the noble gases leads to a discussion of air liquefaction and fractional distillation, and of permeable membrane separation. Water is considered in its multiple roles of coolant, solvent, reactant, and source of elemental hydrogen. Aspects and consequences of air and water pollution are introduced, and emphasis on this all-important topic is maintained throughout the course. Ammonia. This module considers the Haber process for the synthesis of ammonia from gaseous hydrogen and nitrogen, and ammonia’s essential role in the production of fertilizers, polymers, nitric acid, explosives, and a wide variety of chemical products. The synthesis of ammonia offers a unique opportunity to illustrate the impact of chemical industry on global societal issues as well as on history. Sulfuric Acid. The yearly production of sulfuric acid (95.5 billion pounds in the USA in 1998) (4 ) ranks this as the “top industrial chemical”, used as an index of the Gross Domestic Product for industrialized nations. The current industrial process for the synthesis of sulfuric acid is therefore given special attention. The multistage oxidation of sulfur dioxide to sulfur trioxide by air in the presence of a vanadium(V) catalyst, the absorption of sulfur trioxide in concentrated sulfuric acid to give oleum, and the subsequent dilution of oleum to give concentrated sulfuric acid are considered in detail. The module includes the production of sulfur dioxide by the combustion of sulfur or hydrogen sulfide and by the roasting of mineral sulfides. The Frasch process for the extraction of sulfur from underground deposits is described briefly. Nitric Acid. The Ostwald method for the production of nitric acid serves as example of a two-stage thermodynamically
favorable oxidation process—the first stage heterogeneous (ammonia to nitrogen(II) oxide on a platinum–rhodium catalyst) and the second homogeneous (nitrogen(II) oxide to nitrogen(IV) oxide). The conversion of nitrogen(IV) oxide to nitric acid by reaction with water provides an example of disproportionation and recycling, and the final concentration of nitric acid to 98–99% with concentrated sulfuric as the dehydrating agent emphasizes the interdependence of the various branches of the chemical industry. The module concludes with a discussion of the methods used for the removal of nitrogen oxides from the exhaust fumes of nitric acid plants, to prevent air pollution and acid rain. Phosphoric Acid and Fertilizers; Elemental Phosphorus. The “wet process” for the production of phosphoric acid from phosphate rock and sulfuric acid, which accounts for about 90% of the total production, is another example of a major use of sulfuric acid. The importance of phosphoric acid in the fertilizer industry is emphasized (85% of the total phosphoric acid production goes to this use) and various types of fertilizers are considered, including the dual-action “Nand-P” ammonium phosphates. The production of elemental phosphorus from phosphate rock by the arc furnace method and its conversion to the very pure phosphoric acid required by the food and soft drink industry are also considered. Chlor-Alkali Process. The environmentally safe membrane-cell method for the electrolytic production of sodium hydroxide, chlorine gas, and hydrogen gas from aqueous sodium chloride is discussed in detail. The membrane-cell method is compared to the asbestosdiaphragm process and to the older but still widely used process that employs an oscillating mercury cathode. Emphasis is placed on the health problems caused by asbestos and on the mercury-cathode process as a major source of environmental pollution. Metallurgy. Three examples of important processes are considered: copper, iron and steel, and aluminum. COPPER. Copper is the second best metallic conductor of electricity (after silver); it can be drawn into thin wires; and it does not oxidize in dry air. This combination of properties has made copper indispensable to our electricitydependent society. The practical importance of copper makes it an interesting model for a review of the crystal and electronic structure of metals and of the properties that arise from structure. The production of copper metal is considered in its sequence of widely different steps, from the enrichment of minerals to the final electrolytic refining in aqueous solution. Mention is made of the valuable by-products (palladium, platinum, gold, and other elements) recovered from the electrolytic baths. Considered in its entirely, the process illustrates how chemical and physical properties, taken together, provide the theoretical blueprint for the multiphase processes of industrial metallurgy. IRON AND STEEL. Iron is the most widely used metal, and its importance in the development of civilization is recalled with illustration from ancient documents. The module then turns to the reactions and technology of the blast and electric furnaces for the production of cast iron, the modern types of oxygen converters for the production of steel from cast iron, and a survey of the special properties and uses of important types of steel. The use of oxygen (from the
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distillation of liquid air) in the production of steel is another important example of the close interdependence of the various branches of the chemical industry. ALUMINUM. Aluminum is the second most widely used metal and the most abundant (as aluminum compounds) in the earth’s crust. The Hall process serves as example of a nonaqueous electrolytic process for the production of a metal from its thermodynamically very stable and high-melting oxide. The value of the Hall process in the development of modern technology is underscored by a discussion of the low-density, mechanically strong aluminum alloys essential for the construction of aeronautical, naval, and automotive structures. (As a human interest touch, it is mentioned that Hall was an undergraduate student when he conceived the idea of this process.) Silicon, Silica, Silicates and Silicones. Silicon and its compounds are important classes of materials for many hightech applications. The preparation of highly purified silicon from SiO2 and the production of integrated circuits via photolithographic patterning and doping are examples of current technology in this area. The chemistry of silica and silicate is introduced to illustrate the wide variety of properties that can be realized from the oxide and its anionic derivatives. Silicones provide interesting examples of inorganic–organic hybrid polymers that combine high chain flexibility with the excellent thermal stability of the Si–O bond. Comparisons are made between the chemistry of silicon and that of carbon, illustrating the importance of d orbitals in bonding and reaction intermediates. Part II This section of the course presents examples of mid-range and small-scale industrial processes for the production of inorganic fine chemicals, primarily catalysts and products used in the biomedical field. The following topics are considered: 1. The electronic structure and the physical and chemical properties of the transition elements, and correlation to their catalytic functions. 2. Inorganic materials as heterogeneous catalysts: Cu–Zn–Al2O3 catalysts for the hydrogenation of carbon monoxide to methanol. Fischer–Tropsch synthesis of hydrogen and carbon monoxide to produce hydrocarbons and alcohols. 3. Inorganic compounds as homogeneous catalysts: Ziegler–Natta and metallocene catalysts for the polymerization of olefins and acetylenes. Rhodium–phosphine catalysts for the hydroformylation of olefins (Oxo-process). 4. Transition metal complexes used in medicine: Cis-platin and related Pt(II) complexes in cancer therapy. Polychelate complexes of gadolinium(III) as contrast agents in clinical magnetic resonance imaging (MRI). Luminescent complexes of europium(III) as bio-markers in immunoassays.
Implementation and Requirements A difficulty encountered in the implementation of the course has been the lack of a suitable textbook. We solved
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the problem temporarily by reproducing selected sections of Stocchi’s out-of-print book (3i) in booklet format, with the publisher’s permission, and distributing them to the students together with detailed lecture notes and references to comprehensive sources (5). We will also use parts of Chenier’s book (3g), which the chemical engineering students will have already used in the second semester of their sophomore-year organic chemistry course. As a permanent solution, we plan to write a brief text especially designed for this course. The evaluation of the students’ learning is based on four 45-min quizzes (40%), the final examination (30%), and two term papers (30%) on topics that complement the material discussed in class. The term papers are returned with critical comments and are rewritten if not initially satisfactory. They contribute to improving the students’ technical writing ability and skill in gathering information from both printed and electronic sources. The Laboratory Course
Objectives This four-hours-per-week laboratory course exposes the students to activities that illustrate and supplement the topics introduced in the lecture course. It is also intended to help the students develop good laboratory techniques, gain confidence in planning and executing their work, learn to evaluate their results critically, and report them in a manner consistent with the standards of the technical literature. An essential aspect of this laboratory experience is to train the students on safety and management procedures: handling of hazardous reagents and solvents, recycling of recoverable materials, maintenance of laboratory instrumentation, and minimization and proper disposal of chemical waste. Course Content The students perform four multiperiod activities and several short activities intended to introduce them to instrumental methods useful in inorganic and materials chemistry (6 ). The criteria for the selection of the multiperiod activities are (i) overall importance in the inorganic chemical industry, (ii) complementarity to the topics discussed in the lecture course, (iii) adaptability to laboratory scale and available instrumentation, and (iv) exposure to a variety of synthetic and analytical techniques. A brief Laboratory Instructions manual was written and distributed to the students. It includes, in addition to experimental instructions, a fairly extensive discussion of the background, uses, and importance of the chemicals that are the object of each activity. A brief description of the four activities developed so far is given below. Copies of the booklet are available upon request. Copper(II) Phthalocyanine: An Example of a Colored Inorganic Pigment ( 7). Students prepare and purify the pigment by an adaptation of a widely used industrial process, the reaction of phthalodinitrile with copper(I) chloride in an organic solvent at high temperature. Each pair of students then prepares two batches of paint (one latex- and one alkydbased) having known pigment concentrations, uses them to paint wood samples, and measures the color intensity of the dry samples by reflectance spectrophotometry. The entire class finally cooperates in establishing a “pigment concentration versus color intensity” chart for both types of paint.
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In the Classroom
Potassium Peroxydisulfate: Synthesis, Characterization and Reactions (8). Students prepare the electrolyte, assemble the cells for the electrolytic synthesis of the compound, and synthesize and purify the product. The potassium peroxydisulfate is then used to oxidize aniline to the free-base and hydrochloride forms of polyaniline. Samples of the two polymers are pressed into pellets and their electrical resistances are measured and compared. trans-[RhCl(CO){P(C6H5)3}2] and [RhCl{P(C6H5)3}3] (Wilkinson’s Catalyst): Two Examples of Homogeneous Catalysts (9). Students synthesize the two catalysts from rhodium(III) chloride and (commercially available) triphenylphosphine, observing how minor variations in experimental conditions can lead to different products. Wilkinson’s catalyst is then used to hydrogenate an alkene such as cyclohexene. The conversion to the product is followed by GC–MS. Synthesis and Study of “Biomedical-Grade” Polydimethylsiloxane Elastomer Films (10). Students perform the homogeneous cross-linking polymerization of vinylterminated polydimethylsiloxane with methyltris(dimethylsiloxy)silane in the present of a platinum catalyst. At an appropriate stage of the gel-formation process, the reaction mixture is cast into even-thickness films and allowed to cure at room temperature. Both “unfilled” and “filled” polymer films are prepared in this manner and the students measure and compare their elastic properties. In all experiments, the students routinely analyze their products by as many techniques as appropriate (IR spectra, UV–vis spectra of solution, UV–vis–NIR spectra of solids, 1 H NMR and MS spectra, and AA, GC–MS, and TGA), using the instruments under the instructor’s supervision. Our long-range goal is to develop 10–12 activities, from which four are selected each year on a rotation basis. The following new activities are now being adapted to laboratory scale: (i) Synthesis of Silicones and Fractionation Using Supercritical CO2, (ii) Absorption of Sulfur Dioxide: A Laboratory Scrubbing Tower, (iii) “Bright” Nickel and Chromium Electroplating, (iv) Zeolites and Their Use as Heterogeneous Catalysts, (v) Polystyrene and Copolymers from Metallocene-Catalyzed Reactions, (vi) Titanium Dioxide: An Example of a Widely Used White Pigment, and (vii) Synthesis of Polymers Incorporating Magnetic Substances.
Implementation and Requirements The course is conducted entirely in the laboratory and attached instrumental facilities; all necessary instruction is provided in the lab using a pull-down screen and projector. At the beginning of each activity, the students take a quiz related to the background and fundamental aspects of the work to be performed. They then work in pairs and both partners are involved in every aspect of the activity. Each student keeps a research-style laboratory notebook in which is recorded all work performed and any pertinent observations. (The recording is done in the lab as the work progresses, not later at home.) Periodically, the notebooks are collected, examined, and returned with critical comments and suggestions. At the end of the course each student writes a final report that includes all activities with relevant figures, tables of data, and literature citations. The course grade is assigned on the basis of laboratory performance (40%), quiz average (10%), laboratory notebook (25%), and final report (25%).
Critical Evaluation of the Course The experience of the first three offerings of the course (1999–2001) has fulfilled our expectations of the positive aspects of a team-taught interdisciplinary class. The students appreciate the interaction with teachers from different departments and find the different but complementary approaches both instructive and stimulating. They also enjoy discovering the close connection between the practice of largescale industrial inorganic processes and the fundamental principles learned in general chemistry and other chemistry classes, where examples are almost invariably presented at the gram-quantity level. Especially positive has been the response of the students to the laboratory component of the course, where the activities mimic on a laboratory scale some of the industrial processes discussed in the lectures. We will continue to offer this lecture–laboratory course, which we consider to be a constantly evolving project, with the conviction that it will help our students to “hit the ground running” when they enter into their first industrial jobs. Acknowledgments We wish to thank Alfred Bromm and Deborah Polo for their valuable assistance in the development and testing of the laboratory activities. We also appreciate the contribution of K. J. Wynne, who developed the activity on the biomedical-grade poly(dimethyl-siloxane) elastomers. We are grateful to The Camille and Henry Dreyfus Foundation for a generous grant, which supported purchase of the specialized instrumentation required for some of the activities in this course. Literature Cited 1. ACS Committee on Professional Relations. Undergraduate Professional Education in Chemistry: Guidelines and Evaluation Procedures; American Chemical Society: Washington, DC, 1999; pp 12–13. 2. Ferraris, J. P.; Melton, L. A. A Survey of Courses, Texts, and Curricula in Industrial Chemistry; presented at the Industrial and Engineering Chemistry Division Symposium on Education for Industry, ACS National Meeting, Orlando, FL, Aug 24–29, 1996; http://www.udel.edu/ccr/links/lmpaper.html (accessed Feb 2002). Greenbaum, S. B. Chemtech 1994, 24, 9–12. Gumprecht, D. L.; Thrasher, J. S. J. Chem. Educ. 1990, 57, 321–322. Orofino, T. A. J. Chem. Educ. 1989, 66, 420– 21. Baird, M. J. J. Chem. Educ. 1989, 66, 567–569. Szmant, H. H. J. Chem. Educ. 1985, 62, 736–741. Bates, D. K.; Ponter, A. B. J. Chem. Educ. 1985, 62, 745–746. Jasinski, J. P.; Miller, R. E. J. Chem. Educ. 1985, 62, 742–744. Jasinski, J. P. J. Chem. Educ. 1984, 61, 995–996. Chenier, P. J. J. Chem. Educ. 1984, 61, 997–999. 3. (a) Wittcoff, H. A. Industrial Organic Chemicals; Wiley: New York, 1996. (b) Thompson, R. Industrial Inorganic Chemicals, 2nd ed.; Royal Society of Chemistry: Cambridge, UK, 1996. (c) Heaton, A. An Introduction to Industrial Chemistry, 3rd ed.; Blackie Academic and Professional: New York, 1996. (d) Swaddle, T. W. Inorganic Chemistry; Academic: New York, 1996. (e) Greenbaum, S. B. Dynamics of the US Chemical Industry; Kendall/Hunt: Dubuque, IA, 1994. (f ) Agam, G. Industrial Chemicals: Their Characterization and Development; Elsevier: New York, 1994. (g) Chenier, P. J. Survey of Industrial
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Chemistry, 2nd ed.; Wiley-VCH: New York, 1992. (h) Harrison, R. M.; de Mora, S. J.; Rapsomanikis, S.; Johnston, W. R. Introductory Chemistry for the Environmental Sciences; Cambridge University Press: New York, 1991. (i) Stocchi, E. Industrial Inorganic Chemistry; Lott, K. A. K.; Short, E. L., Translators; Ellis Horwood, New York, 1990. (j) Büchner, W.; Schliebs, R.; Winter, G.; Büchel, K. H. Industrial Inorganic Chemistry; Terrell, D. R., Translator; VCH: New York, 1989. (k) Szmant, H. H. Organic Building Blocks in the Chemical Industry; Wiley: New York, 1989. (l) Chang, R.; Tikkanen, W. The Top Fifty Industrial Chemicals; Random House: New York, 1988. (m) White, H. L. Introduction to Industrial Chemistry; Wiley: New York, 1986. (n) Clausen, C. A.; Mattson, G. Principles of Industrial Chemistry; Wiley: New York, 1978. McCoy, M. Chem. Eng. News 1999, 77 (40), 13. Ullman, F. Ullmann’s Encyclopedia of Industrial Chemistry, 6th ed.; VCH: New York, 2000. Riegel, E. R. Riegel’s Handbook of Industrial Chemistry, 9th ed.; Kent, J. A., Ed.; Chapman & Hall: New York, 1992. Kirk, R. E.; Othmer, D. F. Kirk–Othmer Encyclopedia of Chemical Technology, 4th ed.; Grant, M.-H., Ed.; Wiley: New York, 1991. Ellis, A. B.; Geselbracht, M. J.; Johnson, B. J.; Lisensky, G. C.; Robinson, W. R. Teaching General Chemistry: A Materials Science Companion; American Chemical Society: Washington, DC, 1993. Moser, F. H.; Thomas, A. L. Phthalocyanine Compounds; Reinhold: New York, 1963. Lever, A. B. P. Adv. Inorg. Chem. Radiochem. 1965, 7, 27–114. Kirk, R. E.; Othmer, D. F. Kirk–
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Othmer Concise Encyclopedia of Chemical Technology, 3rd ed.; Grayson, M.; Eckroth, D., Eds.; Wiley-Interscience: New York, 1985; pp 887–892, 1985. Riegel, E. R. Riegel’s Handbook of Industrial Chemistry, 9th ed.; Kent, J. A., Ed.; Chapman & Hall: New York, 1992; pp 1062–1067. Shur, E. G. Interchem. Rev. 1952, 15 (2), 30–31. 8. Durrant, P. J.; Durrant, B. Introduction to Advanced Inorganic Chemistry; Longmans: London, 1962; pp 850–851. Minisci, F.; Citterio, A.; Giordano, C. Acc. Chem. Res. 1983, 16, 27–32. Angelici, R. J. Synthesis and Technique in Inorganic Chemistry; Saunders: Philadelphia, 1977; pp 179–185. Focke, W. W.; Wnek, G. E.; Wei, Y. J. Phys. Chem. 1987, 91, 5813–5818 and references therein. Wei, Y.; Wang, J.; Jia, X.; Yeh, J.–M.; Spellane, P. Polymer 1995, 36, 4535–4537. 9. Osborn, J. A.; Wilkinson, G. In Inorganic Syntheses, Vol. 28; Angelici, R. J., Ed.-in-Chief; Wiley: New York, 1990; pp 77– 79. Evans, D.; Osborn, J. A.; Wilkinson, G. Ibid.; pp 79-80. Collman, J. P.; Hegedus, L. S.; Norton, J. R.; Finke, R. G. Principles and Applications of Organotransition Metal Chemistry; University Science Books: Mill Valley, CA, 1987; pp 530– 537, 625–632. 10. Pike, J. K.; Ho, T.; Wynne, K. J. Chem. Mater. 1996, 8, 856. Bullock, S.; Johnston, E. E.; Willson, T.; Gatenholm, P.; Wynne, K. J. J. Coll. Inter. Sci. 1999, 210, 18. Lindner, E. Biofouling 1992, 6, 193. Newby, B. Z.; Chaudhury, M. K. Langmuir 1998, 14, 4865. Griffith, J. R. U.S. Patents 5,449,553, 1995, and 5,593,732, 1997.
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