Ind. Eng. Chem. Res. 1991,30,807-811 Resins. (with T. T. Shih) Recent Deuelopments in Separation Science; N. N. Li, Ed., CRC Press: Cleveland, 1977; Vol. IIIA, p 129. Absorption of Nitrogen Dioxide into Water, Sulfuric Acid, Sodium Hydroxide, and Alkaline Sodium Sulfite Aqueous Solutions. (with Y. Kameoka) Ind. Eng. Chem. Fundam. 16, 163 (1977). Theory and Practice: Can Chemical Engineering Get Its Act Together? Chem. Eng. Prog. 74 (9), ll (1978). Report to the American Physical Society by the Study Group on Nuclear Fuel Cycles and Waste Management. (with E. L. Christensen, F. A.Donath, W. E. Falconer, L. C. Hebel, L. J. Lidofsky, E. J. Moniz, T. H. Moss, and T. H. Pigford) Reo. Mod. Phys. 50, 185 (1978). Ion-Exchange Rates in Bifunctional Resins. (with D. D. Cobb, K. S. Knaebel, and T. T. Shih) Ind. Eng. Chem. Fundam. 18, 175 (1979). Properties of the Amphoteric, Thermally Regenerable Ion-Exchange Resins Amberlite XD-2 and Amberlite XD-5. (with T. B. Hsu) Ind. Eng. Chem. Prod. Res. Deu. 20, 361 (1981). Absorption of Nitric Oxide in Nitric Acid and Water. (with G. Carta) Ind. Eng. Chem. Fundam. 22, 329 (1983).
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Equilibrium and Dissipative Effects in Cycling Zone Adsorption. (with K. S. Knaebel) Znd. Eng. Chem. Fundam. 22, 336 (1983). Flow Distribution in Piping Manifolds. (with M. Ashraf and Y. D. Miron) Ind. Eng. Chem. Fundam. 22,463 (1983). Integrating Chemistry and Engineering: A Course in Industrial and Engineering Chemistry. (with G. L. Schrader and B. C. Gates) Chem. Eng. Educ. 17,16-19,42-46 (1983). Kinetics of Phase Transitions in the System Sodium Sulfate-Water. (with D. Rosenblatt and S. B. Marks) Ind. Eng. Chem. Fundam. 23, 143 (1984). Periodic Countercurrent Operation of Sorption Processes Applied to Water Desalination with Thermally Regenerable Ion-Exchange Resins. (with G. Carta) Ind. Eng. Chem. Fundam. 25,677 (1986). Analytical Solution for Cycling Zone Adsorption. (with G. Carta) Chem. Eng. Sci. 41, 511 (1986). Salt Removal from Water by Continuous Ion Exchange Using Thermal Regeneration. (with T. B. Hsu) Znd. Eng. Chem. Res. 28, 1345 (1989). The Probability Distribution of Growth Rates of Anhydrous Sodium Sulfate Crystals. (with D. L. Klug) Znd. Eng. Chem. Res. 28,1718 ( 1989).
Robert L. Pigford: A Prince among Men Richard E. Emmert, Harold S. Kemp, Arthur B. Metzner,* and Charles R. Wilke Robert L. Pigford was born on April 16,1917 and died on August 4, 1988. Thus, his lifetime spanned the full period of the early dynamic growth of chemical engineering and of the maturing of the chemical engineering profession. He was one of the best known and most admired leaders of his profession and his name was synonymous with erudition and rigor, with warmth and helpfulness to his colleagues everywhere, and with Southern gentlemanly courtliness and elegance. Born and raised in Meridian, MS, he was encouraged to excel in whatever he undertook. Early interests embraced the emerging marvels of radio as well as musicinterests never fully set aside, even though the chairman of the chemistry department at his undergraduate school, Mississippi State College, swayed his professional interests. Early projects at home included construction of model airplanes and of a crystal set, and as a teenager he assembled the first of an unending array of ham radios. Principal preoccupations during the teenage years were his studies, these hobbies, and music. He was a leader in his high school, Mississippi State, and ROTC bands as a youth. One of the few academic activities in which he did not excel was a high school course in economics-a subject taken only at the insistence of a father who felt his son would profit from instruction in this subject. This academic excursion into an area in which he had no interest cost him the opportunity of becoming the valedictorian of his class: this distinction went instead to Marian Pinkston, whom he married in 1939. Upon receiving his baccalaureate in 1938 from Mississippi State College he enrolled in graduate studies at the University of Illinois. This was a great blow to the pride of his father who had assumed his son would surely learn all that was necessary as an undergraduate! Graduate studies enabled Robert Pigford’s enthusiastic immersion into the frontiers of his profession. M.Sc. and Ph.D. degrees were awarded in 1940 and in February of 1942, respectively. The Pigfords moved to Delaware in August of 1941 when he accepted employment with the technical division of the Engineering Department of E. I. duPont de Nemours and Company, Inc., in Wilmington. Here he encountered the professional invigoration of a host of very able colleagues, of the laboratory director, Thomas H. Chilton, and of numerous consultants who visited regularly,
including Allan P. Colburn (University of Delaware), Thomas H. Drew (Columbia University), and William H. McAdams (Massachusetts Institute of Technology). This industrial laboratory was conducting research to build, from the most modest base that existed at the time, fundamental knowledge that could be used in design procedures and standards. This work required research measurements and their correlation, the development of models to represent processes, and the translation of all of this into usable design methods. Much of the basis for this work came from troubleshooting and analysis of actual processes. Working in this challenging environment, Robert Pigford contributed significant advances in a variety of areas. A partial listing of these is as follows: 1. The operation of both spray-type and plate-type absorbers was studied for the recovery of selected components of a gas stream. Increased recovery (with concomitant pollution abatement) and increased equipment capacity were the usual goals sought. This work also provided an early contact with absorption accompanied by chemical reaction, a subject in which he was to become a leader in his subsequent academic career. 2. Experiments on laminar, turbulent, and boiling heat transfer, leading to improved correlations of rate coefficients, were carried out on both laboratory and semiworks scales. 3. Computations of the power requirements needed for separation of isotopes by diffusion cascades and by centrifuges were made for wide ranges of molecular weight ratios, pressures, flow rates, and degrees of separation, all in support of his corporation’s involvement in the Manhattan Project. 4. Measurements of the atmospheric dispersion rates of droplet clouds, of interest in both defensive and offensive chemical warfare during World War 11, were carried out using balloons to carry the experiments aloft. This led to one of his most celebrated mishaps, when a large balloon carrying harmless simulants broke loose and drifted across the river to New Jersey. The civil defense forces identified the intruder as the onset of an enemy gas attack and mobilized the military over a large area to initiate a counterattack. 5. Use of plant-scale studies of packed distillation
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columns, and extensive calculations for plate columns, when hold-up of liquid in the column is a significant fraction of the batch charge, were made to improve separation processes for specialty chemicals of high cost and of small production. Such production facilities were characteristic of many products needed during World War 11. This familiarity with distillation would serve him well later when, in the early days of numerical calculations, exhaustive studies of distillation process transients were needed to improve the productivity of the Savannah River Plant for the production of heavy water. 6. Application of differential equations to the solution of chemical engineering problems, practiced routinely in his work, led him and a colleague, the late W. R. Marshall, to offer a course on this subject at the University of Delaware, Their ensuing textbook, The Application of Differential Equations Chemical Engineering Problems, long out of print, is still requested regularly to this daynearly half a century later. Shortly after joining Du Pont, Robert Pigford began his association with the University of Delaware on a part-time basis, teaching evening and weekend courses. Some of those enrolled were full-time graduate students, but most were industrial colleagues interested in strengthening their professional backgrounds through formal associations with this unique scholar. Chemical engineers in the Delaware Valley soon learned that this university’s Saturday morning extension courses were occasions for intense and warm professional socializing as well as for vigorous scholarship, as young full-time students and experienced professionals wrestled together to master the apparently unending store of intellectual challenges that Robert Pigford and his associates continued to provide. In 1947 Allan Colburn, noting that Robert Pigford was spending increasing fractions of his evening and weekend hours on campus, invited him to come to the University of Delaware during weekday daylight periods as well. The invitation was to provide an appointment to him, at age 30, as chairman of the department. Robert Pigford consulted his industrial friends and supervisors about the wisdom of such a move; their response was to advise him to make a two-column listing of the objective advantages under each career alternative. Of course, they were confident that a continuing productive career in the nation’s leading chemical company would appear much more attractive than the alternative of work in a fledgling department in an underdeveloped university with no Ph.D. programs and with few resources. And, just as they had anticipated, when the listing was made, nearly all of the objective advantages were with the industrial option. But, of course, there were also nonquantifiable, subjective attractions to the university option: that of forging a new department and, indeed, of assisting in the development of an entire university; the opportunity of working with succeeding generations of young scholars and of assisting in a developing renaissance of his profession; the opportunity, in Robert Pigford’s words “to have fun professionally”. We all know what his choice was, but this story was the basis of his frequent advice to students and to younger colleagues in subsequent years: “Always choose the professional alternative which you would find to be the most enjoyable. It is only by making this choice that you will throw yourself into your work with sufficient enthusiasm and vigor to become an accomplished professional and, as a by-product, a serene and supportive spouse and parent.” And what fun it was for all of us who were to be associated with him! We learned to laugh together as well as
to work together; and to live together: Marian and Robert Pigford opened their hearts as well as their home to our families, and we benefited unashamedly from their devotion to this their family of scholars. Former graduate students remember Saturday night parties in the Pigford home, where they were introduced to the Pigford love for music and to the myriad joys that accompany a family setting. Comparably, faculty colleagues were introduced to colleagues in other departments, and to the university administration, in a gracious social setting conducive to discussion of their diverse interests, opportunities, and problems. If any of us who were long-term friends of the Pigfords developed some altruistic qualities, it would have been due, in large measure, to their inspired example. Administration of a leading department brings with it the need for resolution of generic university problems as they tend to arise earlier in these situations than elsewhere on a campus. Robert Pigford did not enjoy the many administrative chores his position implied. But he dealt with them forthrightly. Several of his colleagues remember his unique manner of seeking advice on major administrative issues. All faculty offices, in those long ago days in Brown Laboratory, were along one corridor, with the chairman‘s at one end and the most recently appointed assistant professor at the other. Robert Pigford simply gathered any papers necessary for a discussion of the issue in one hand and, with a pad and pencil in the other, proceeded to interview each faculty colleague in turn. When he came to the end of the hallway, perhaps no more than 30 min later, he had all the information he needed for an informed decision-and none of his colleagues were diverted from their activities for more than a few minutes each. How nostalgically one looks back upon such a straightforward procedure in these days of excessive committee responsibilities! Once, in a social gathering at which this Pigford procedure was described to a faculty friend from another department, the latter queried, “But how could you be sure he would accept your advice?” And we who were his friends were speechless: this was simply an unthinkable question, an unthinkable occurrence in the Pigford department. Of course he would accept advice if he requested it; his generosity of spirit was such that intrigues between him and his colleagues were simply unthinkable. In turn his colleagues were usually equally ready to grant him discretion in use of any advice he sought. Such indeed was the Pigford department: one administered by mutual altruism. And his vision for his university was that all departments would some day, too, share in such altruism. Can there be a more beautiful legacy? Professionally, under Robert Pigford’s leadership the department developed rapidly to become one of primary stature nationally. He became one of the most vigorous and most effective advocates of the need to combine engineering science with industrial practice to develop the art as well as the science of the discipline, and of the need to graduate practitioners with creative as well as analytic skills. Professor Pigford had a major impact on the profession through his books, lectures, and extensive research papers, and through the activities of a large group of former students and visting faculty who have become leaders in the field around the world. He was one of the earliest proponents of the use of computers in engineering and built several for both instruction and research before the widespread availability of such equipment. A t the time, one of the modern subjects for attack by extensive numerical calculations was that of mass transfer accompanied by chemical reaction. While empirical cor-
Ind. Eng. Chem. Res., Vol. 30, No. 5, 1991 809 relations, restricted to very specific chemical systems, had been available for some time, there was little scientific material of any generality. Indeed, the bulk of the literature on this subject, ca. 1950, consisted of largely qualitative physiological observations reported by medical practitioners. Buoyed by his earlier industrial exposure to this subject, Pigford and his students set forth with vigor using first their homemade computers and then a giant vacuum-tube-based machine at Aberdeen Proving Ground, one of only a few available nationally and which the military made available to him on the midnight4:OO a.m. shift. Robert Pigford, long a late-night worker, availed himself of this computational opportunity with enthusiasm, some of his graduate students less so. The Interstate Highway Network had not yet been developed, and the 35 miles separating Aberdeen and Newark were on roadways shared with cruising teenagers on the evening trip to Aberdeen and with sleepy long-distance truck drivers on the return. And, those of us who were early risers viewed our rumpled and bleary-eyed colleagues when they returned to the Delaware campus at about the time other people go to work. Students enthusiastically anticipated the end of these all-night vigils when the university purchased its first computer. Their joy was short-lived, however: while the administration was pleased to make this modern tool available they could not be convinced that “machines” needed to be air conditioned to work properly in the heat of the Delaware summer. And, if they were, would all the faculty not also clamor for such an effete frivolity? Consequently, for some time, this computer, too, could only be employed at night except during the winter months. However, the 70-mile round trip to Aberdeen was happily avoided. The activity also led faculty from other departments to begin serious computational activities and, shortly, under Robert Pigford’s leadership, to the establishment of a computing center for the University community. Professor Pigford’s long career with the University of Delaware was suspended for a decade beginning in 1966 while he served as Professor of Chemical Engineering at the University of California at Berkeley. However, by that time he was no stranger there, having spent a semester as a Visiting Professor in the spring of 1954. The faculty of that relatively new department had invited him to come in the belief that an association with this much-admired young chemical engineering educator might provide valuable guidance and perspective. This indeed proved to be the case and Robert was later welcomed back most enthusiastically by all when he was persuaded to accept a permanent appointment. During his initial visiting appointment Professor Pigford continued his active interest in computing and conveyed his enthusiasm and valuable knowledge of this new field to other members of the faculty. A t that time Berkeley had no computing facilities so that it was necessary to drive about 40 miles to the Livermore (Atomic Energy) Laboratory during the night shift when off-peak time was available. A repetition of the Aberdeen Proving Ground saga: on many evenings, with two or three colleagues, he would leave Berkeley about 500 p.m. and not return until 2:OO or 300 a.m.! The early computers at Livermore were IBM CPC models which ran slowly with card input and arduously programmed machine language. To make maximum use of the time, Robert would usually run two, and sometimes three, of these computers simultaneously, feeding the output cards from one as input to another. As a result of these unusual techniques he became known as “Rapid Robert” to some of his companions. His skill and
the results obtained were inspiring and had a lasting influence in bringing the department into the computer age more rapidly than would have been the case otherwise. During his years at Berkeley Professor Pigford pursued a vigorous program of teaching and research. His thesis supervision covered a wide range of subjects including crystallization from melts, removal of sulfur dioxide from hot gases by chemical absorption, and, most notably, development and theoretical analysis of a new technique to enhance adsorption by cyclically alternating the temperature levels of columns operating in series. He was awarded a U.S. patent jointly with his graduate students Burke Baker I11 and Dwain Blum for this process named “Cycling Zone Adsorption”. His research typically involved difficult problems that were in need of experimental insight and theoretical analysis, and also had promise of contributing to industrial practice. Professor Pigford enjoyed teaching at all levels. In addition to advanced courses he frequently taught a lower division thermodynamics course taken by chemistry and life-science students as well as by chemical engineers. He offered a voluntary course for graduate students in electronics that he believed to be important to the understanding of modern computing and instrumentation. As a member of the College of Chemistry Computing Committee he contributed importantly to the planning and development of computing facilities at Berkeley. In the development of the chemical engineering curriculum he provided a valuable influence in bringing the needs and viewpoints of industry into faculty discussions and into his own courses. Professor Pigford was amazingly versatile and quick to learn new subjects. At Berkeley he continued his worldwide ham radio contacts and mounted a three-story antenna tower in his back yard. A skilled craftsman, he enjoyed making pieces of furniture, including grandfather clocks, and electronic devices, and would offer to make these for his friends as gifts. He continued his interest in music by playing clarinet in local orchestras. On the occasion of a celectration of the 70th birthday of Professor T. K. Sherwood he wrote an arrangement of “Happy Birthday” including the instrumental scores for the unlikely combo of clarinet, oboe, and trombone: the instruments for which talented players were available. Professor Pigford played a very significant role in the development of chemical engineering in the University of California. When he decided to return to his first academic love, the University of Delaware, all at Berkeley felt a sense of great loss. Robert and his wife, Marian, had become a valued and highly respected part of the University community. And, in view of his earlier service on Athletic Boards it was difficult for his Berkeley colleagues to accept his preference for a university having a Blue Hen as a mascot over that of a handsome Golden Bear! In addition to creating new knowledge by research, throughout his career Professor Pigford contributed much to the chemical engineering literature, including books and numerous papers in technical journals. Notable books include T h e Application of Differential Equations to Chemical Engineering Problems with W. R. Marshall; Adsorption and Extraction, 2nd ed.,with T. K. Shemood; and Mass Transfer with T. K. Sherwood and C. R. Wilke. The Diffusional Operations, Gas Absorption, and Distillation sections of Perry’s Chemical Engineers’ Handbook, 3rd ed., were coauthored with A. P. Colburn, and the Gas Absorption and Liquid Extraction section of the fourth edition of the handbook was coauthored with R. E. Emmert. A major publication activity, and a tremendous and
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time-consuming service to the profession, were his quarter century’s service as the Editor of the Industrial & Engineering Chemistry Fundamentals quarterly. During his editorship Professor Pigford spent countless hours reviewing and arranging the publication of hundreds of manuscripts from all around the world. His reviews of papers and decisions were always made with great courtesy and constructive comment for the authors. Robert Pigford’s advice was sought by numerous industrial, academic, and governmental institutions. He served as a member of the US. Army’s Research Council, the Scientific Advisory Board of the U.S. Air Force, the Department of Energy, the National Research Council, the American Society for Engineering Education, and the advisory committees for chemical engineering departments a t Massachusetts Institute of Technology and Princeton University. He was deeply concerned by, and interested in, the ethical dimensions of science and technology and served much time on national committees devoted to clean air standards and to the safe disposal of nuclear wastes. In this latter activity he worked closely with his younger brother, Thomas, a distinguished nuclear engineering faculty member at the University of California at Berkeley. From 1983 until his death, Robert Pigford served as the gubernatorially appointed faculty representative on his university’s Board of Trustees. Professionally, Robert Pigford received almost all the awards for leadership in research and education of his principal professional society, the American Institute of Chemical Engineers. On the occasion of the Institute’s 75th anniversary he was named as one of 30 preeminent leaders of the chemical engineering profession. He was elected to the National Academy of Engineering in 1971 and to the National Academy of Sciences in 1972-one of only a very small number of scholars nationally to have been accorded this double honor. The University of Delaware recognized Robert Pigford’s distinction by bestowing on him the unique title of University Professor in 1975 and by naming him as its first Alison scholar in 1977. His own alma mater, Mississippi State College, granted him its Outstanding Achievement Award in 1978, on the centennial of that institution’s College of Engineering. In 1988 he was named Delaware’s Engineer of the Year by the Delaware Society of Professional Engineers. Too sensitive to criticize others openly in view of his Southern heritage, he nevertheless enjoyed opportunities to expose any charlatan. Opportunities to do so arose with considerable regularity, and can be exemplified by the following anecdote. Hot-wire anemometry was in its golden era in the years following World War 11, with progressively finer wires being produced by engineers of many persuasions, to enable their probing of progressively higher frequencies of the turbulent flow spectrum. These were, of course, very difficult to produce and to operate as any impinging speck of dust would cause their destruction; wind tunnels of the era were not noted for their cleanliness. On an occasion when the Pigford department was being regaled by a visiting seminar speaker who claimed he could decrease the diameter of these wires by an order of magnitude from the best then available, his assertion was met with great disbelief by the graduate student body, many of whom had struggled valiantly to attain far more modest gains. The speaker stood his ground, however, against an increasingly hostile onslaught of skeptical queries, claiming that O.l-Fm wires would be produced in his laboratory “within days”, and mounted in the anemometer by simple “hold-it-in-your-fingersand-solder-it” techniques. When an impasse appeared to
be fast approaching, Professor Pigford entered into the discussion with what appeared initially to be an alarming and one-sided joining of forces with the visiting speaker: “I am quite willing to believe you can indeed produce such a fine wire, if you state you can do so. However, noting that its diameter is smaller than the wavelength of visible light, if you did produce it, would you be able to find it? Could there have been any gentler, more elegant, and yet more conclusive finale for this discussion? For all the professional achievementsof the man, Robert Pigford was an uncommonly sensitive and human individual. Those who knew him knew a gentle, unassuming person, always concerned about the feelings of others. He constantly tried to help those around him achieve excellence, and he managed to do it in a noncompetitive way. At the same time, he insisted on working on things that are relevant. In these ways, he had an immeasurable uplifting influence on not only his students and associates, but also on the many people in the organizations with which he worked as a consultant. It was surely this human side of the man that caused such an outpouring of affection on the occasion of a special 70th birthday event held in his honor at the University of Delaware, and several of the stories told on that occasion warrant repetition here. One former graduate student recalled receiving a Saturday midnight call from a colleague in the laboratory advising that a considerable flow of water was cascading into the basement below Professor Pigford’s office. Could its source possibly be in your laboratory just above the office? A quick trip to the laboratory confirmed the worst of the student‘s fears. Undoubtedly, the flow of water from his laboratory must have soaked the Pigford office, the books and papers of the departmend chairman, on its way to the basement. Dare one call the chairman at this hour of the night? But there seemed to be no alternative as any delay would only multiply the damage already done. and, in due course, Robert Pigford arrived in overalls, with a mop and pail, and with the gentlest of all possible admonitions: “Don’t worry, these things happen.” He was also ready to help his colleagues with any personal issues they brought before him. One of his colleagues, knowing Robert Pigford to be a lover of music and very able clarinetist, recalled asking for advice concerning the purchase of a clarinet for his child. The response was a very professional one: “Neither the instruments themselves nor the reeds and mouthpieces for clarinets are very reproducible. In general, however, you should only consider two manufacturers. One of them produces better mouthpieces and the other better instruments. Collect all you can from the several Delaware stores, bring them to our house tonight and we will choose the combination which sounds best.” And this was done. The entire Delaware supply of clarinets was brought to the Pigford home and the choice was made by the child and Robert Pigford playing Mozart duets. The visitors to the Pigford home were a part of the extended Pigford family, and, as such, their needs took precedence over any earlier plans for the evening. Another story with which to close: A new student had been assigned to share a laboratory with another of Robert Pigford’s graduate students-the late Robert H. Perry. The latter individual advised the new student that he was in for a demanding but inspiring experience, for, he said, you will be working with “ A prince among men”. How many times have each of us, the numerous authors of this tribute, witnessed Robert Pigford as a productive engineer, as an educator, as a scholar, as a friend, and thought-“Yes-a prince among men ”. We are privi-
Ind. Eng. Chem. Res. 1991,30, 811-821 leged to have been among his colleagues. Acknowledgment This tribute has been submitted for publication to Industrial &E Engineering Chemistry Research as well 8s to the National Academy of Sciences’ Biographical Memoirs, where it will appear in Vol. 65. The generosity of both organizations in permitting this dual publication is appreciated. Richard E. Emmert received his Ph.D. degree under Dr. Pigford’s direction and had many consulting associations in later years
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while an employee of E. I. du Pont de Nemours and Company. He is now Executive Director, American Institute of Chemical Engineers. 345 East 47 Street, New York, NY 10017. Harold S . Kemp received his.doctorate Ad joined E. I. du Pont de Nemours and Company at about the same time as Robert pigford, For many years they shared an office later, during Prof. Pigford’s academic tenure, continued their professional association on a consulting basis. Dr. Kemp, a former president of AIChE, is now retired and resides at 20 Crestfield Road, Wilmington, DE 19810. Professors Metzner and Wilke knew Professor Pigford over many decades as a faculty colleague, the former at the University of Delaware and the latter at the University of California at Berkeley.
Catalytic Conversion of Synthesis Gas to Methanol and Other Oxygenated Products Alvin B. Stiles,* F r a n k Chen, J e f f r e y B. Harrison, Xiaodong Hu, David A. S t o r m , and H. X.Y a n g Center for Catalytic Science and Technology, Department of Chemical Engineering, The University of Delaware, Newark, Delaware 19716 This paper reports the results obtained in an extended program on the conversion of synthesis gas to methanol and higher alcohols. Modifications were made in the catalyst composition, method of fabrication, promoters, and moderators. Test conditions were also modified as a temperature, pressure, gas composition, space velocity, and production rate. Methane and other hydrocarbon production was held to less than 5% of the CO reacted. Product could be controlled as to the percent of higher alcohols in the anhydrous product to between 0 and 80%, and the identity of the alcohols could be controlled to predominantly ethanol, propanol, or isobutyl alcohol; these factors plus high production rates give the process exceptional commercial appeal. An unexpected result of the effort was observing that substantial percentages of acetaldehyde, propioaldehyde, isobutyraldehyde, and methyl ethyl ketone could be produced, which translates to acetic and propionic acids and methyl tert-butyl ether. As a result of the extensive data, a new alcohols synthesis mechanism is proposed. The catalytic direction of synthesis gas to specific products is one of the most striking examples of the specificity and directivity of catalysts. One of the most specific reactions for synthesis gas is that of its conversion to methane over a nickel or ruthenium catalyst, the products being essentially 100% methane. The other leg of the specificity spectrum is the conversion of synthesis gas to methanol in over 99% yield and very high production rate (Berkman et al., 1940; Davies et al., 1967; Dodge, 1933; Frolich and Lewis, 1928; Stiles, 1977, 1978; Wentworth and Stiles, 1980; Casey et al., 1974; Hydrocarbon Process., 1969a-c). This is usually performed over a catalyst comprised of copper, zinc, and aluminum or chromium oxides. Between these two extremes are processes whereby synthesis gas can be converted to methanol plus high alcohols and some other oxygenated products (Klier, 1980;Larson, 1936; Morgan and Hardy, 1933;Smith and Anderson, 1983; Sabatier, 1923;Stiles, 1985;Sugier and Freund, 1978, 1981; Courty et al., 1982; Wunder, 1980). Other examples are the conversion of synthesis gas to Fischer-Tropsch products over a promoted iron, cobalt, or ruthenium catalyst (Fischer and Tropsch, 1921; 1923; Mittasch and Schneider, 1913). Other examples are the conversion of synthesis gas to ethylene glycol and to long straight-chain alcohols. The former is conducted with a rhodium catalyst, moderated with a bromine or iodine organic halide. The long straight-chain alcohols are produced at relatively high pressures and low temperatures over a ruthenium catalyst (unpublished Du Pont work)
The primary objective of our work has been to economically convert synthesis gas to methanol and specific higher alcohols while simultaneously producing controlled quantities of aldehydes and methyl ethyl ketone (MEK). This research is one of the outstanding examples of cooperation between university and corporate researchers. The development of a catalyst or a family of catalysts and process conditions has made it potentially possible for the economical, commercial synthesis of methanol and higher alcohols of both specific quantity and identity. The proportion of higher alcohols is such that the mix could be added to gasoline and have it miscible in all proportions and under all temperature conditions. This required that methanol be produced with at least 2090 higher alcohols in the crude product and preferably 30% if this level could be economically and efficiently attained. This objective has been attained, but as is customarily the case, there are incidental discoveries made during the research that make the objective more complex than as originally established. It is noteworthy and reassuring that although the synthesis of alcohols from synthesis gas has been a topic of research for at least 75 years, there are still many valuable inventions to be made. A case in point is that there was no time during the course of this study that an important invention or discovery was not made in a given quarter. In the description of our research and research results that follow, we will attempt to take the reader along our journey of effort in a manner that should show the stepby-step progress and thought-by-thought development of
0888-5885/91/2630-0811$02.50/0 0 1991 American Chemical Society
