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Catalysis Looks to the Future Executive Summary SOCIETAL IMPACT OF CATALYTIC SCIENCE AND TECHNOLOGY The chemical industry is one of the largest of all U.S. industries, with sales in 1990 of $292 billion and employment of 1.1 million.1 It is one of the nation's few industries that produces a favorable trade balance; the United States now exports chemical products amounting to almost twice the value of those that it imports (exports of roughly $37 billion compared to imports valued at about $21 billion).2 Between 1930 and the early 1980s, 63 major new products and 34 process innovations were introduced by the chemical industry. More than 60% of the products and 90% of the processes were based on catalysis. Catalysis also lies at the heart of the petroleum refining industry, which had sales in 1990 of $140 billion and employed 0.75 million workers.3 Clearly then, catalysis is critical to two of the largest industries in sales in the United States; catalysis is also a vital component of a number of the national critical technologies identified recently by the National Critical Technologies Panel.4 Looking into the future, one can see many exciting challenges and opportunities for developing totally new catalytic technologies and for further 1 U.S. Department of Commerce, U.S. Industrial Outlook 1991, International T rade Administration, Washington, D.C., 1991. 2 U.S. Department of Commerce, U.S. Industrial Outlook 1991. 3 U.S. Department of Commerce, U.S. Industrial Outlook 1991. 4 Report of the National Critical Technologies Panel, William D. Phillips, chair, Arlington, Va., March 1991.
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Catalysis Looks to the Future improving existing ones. Increasing public concern with the effects of chemicals and industrial emissions on the environment calls for the discovery and development of processes that eliminate, or at least minimize, the use and possible release of hazardous materials. Concern with the environment and the supply of raw materials is also focusing attention on opportunities for recycling. Of particular interest for the chemical industry is the prospect of producing polymers that are readily recyclable. Although the world supply of petroleum is adequate for current demand, there is a need to continue the search for technologies that will permit the conversion of methane, shale, and coal into liquid fuels at an acceptable cost. Also, to maintain their economic competitiveness, U.S. producers of commodity and fine chemicals will need to shift to lower-cost feedstocks and processes exhibiting higher product selectivity. Taken together, these forces provide a strong incentive for increasing research efforts aimed at the discovery and development of novel catalytic processes and for continuing to extend the frontiers of catalytic science. The following are benchmark discoveries made over the years in the science and technology of catalysis: 100 years ago: Paul Sabatier (Nobel Prize 1912) at the University of Toulouse started work on his method of hydrogenating organic molecules in the presence of metallic powders. 70 years ago: Irving Langmuir (Nobel Prize 1932) at General Electric laid down the scientific foundations for the oxidation of carbon monoxide. 50 years ago: Vladimir Ipatieff and Herman Pines at UOP developed a process to make high-octane gasoline that was shipped just in time to secure the victory of the Royal Air Force in the Battle of Britain. 30 years ago: Karl Ziegler and Giulio Natta (Nobel Prize 1963) invented processes to make new plastic and fiber materials. 17 years ago: W. S. Knowles at the Monsanto Company obtained a patent for a better way to make the drug L-Dopa to treat Parkinson's disease. Today: Thomas Cech (Nobel Prize 1989) at the University of Colorado received U.S. patent 4,987,071 to make ribozymes, a genetic material that may, one day, be used to deactivate deadly viruses. The above examples deal with materials for health, clothing, consumer products, fuels, and protection of the environment, but all have a common feature: they rely on chemical or biochemical catalysts. WHAT ARE CATALYSTS? What are catalysts, these substances that hold the keys to better products and processes, and continue to have a strong impact on our health, economy, and quality of life? A catalyst is a substance that transforms reactants into
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Catalysis Looks to the Future products, through an uninterrupted and repeated cycle of elementary steps, until the last step in the cycle regenerates the catalyst in its original form. More simply put, a catalyst is a substance that speeds up a chemical reaction without itself being consumed in the process. Many types of materials can serve as catalysts. These include metals, metal compounds (e.g., metal oxides, sulfides, nitrides), organometallic complexes, and enzymes. CATALYTIC SCIENCE AND TECHNOLOGY The first triumph of a large-scale catalytic technology goes back to 1913 when the first industrial plant to synthesize ammonia (NH3) from its constituents, elemental nitrogen (N2) and elemental hydrogen (H2), was inaugurated in Germany. From the outset, and until the present, the catalyst in such plants has consisted essentially of iron. The mechanism of the reaction is now well understood. Certain groups of iron atoms at the surface of the catalyst are capable of dissociating first a molecule of nitrogen and then a molecule of hydrogen, and finally of recombining the fragments to ultimately form a molecule of ammonia. The catalyst operates at high temperature to increase the speed of the catalytic cycle and at high pressure to increase the thermodynamic yield of ammonia. Under these conditions, the catalytic cycle turns over more than a billion times at each catalytic site, before the catalyst has to be replaced. This high productivity of the catalyst explains its low cost: the catalyst results in products worth 2000 times its own value during its useful life. The next illustration of catalysis shows that industrial catalysts can be biomimetic in the sense that they imitate the ability of naturally occurring enzymes to produce optically active molecules. Many pharmaceuticals are known to be active in only one form, let us say the left-handed form. It is therefore critical to obtain the left-handed form with high purity. It is particularly important when the drug is toxic, even if only slightly so, and must be administered over many years. It is true of a molecule called L-Dopa used in the treatment of Parkinson's disease. The right-handed molecule is inactive. In ordinary synthesis, both forms are produced in equal amounts. Their separation is costly. Is it possible to produce only the left-handed form by means of a synthetic catalyst? The first successful industrial synthesis of this kind was achieved by Monsanto, and a patent for the selective synthesis of L-Dopa was granted in 1974. The catalytic process used to make L-Dopa today is an important achievement in industrial catalysis. Finally, recent and current developments in catalytic technology are targeted at the protection of the environment. The best-known example deals with catalytic converters that remove pollutants from the exhaust gases of automobiles. Catalytic converters for automobiles were first installed in the United States in the early 1970s. These devices were subsequently intro-
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Catalysis Looks to the Future duced in Japan and are currently spreading through the European Community and Switzerland. The most advanced catalyst now contains three metals of the platinum group and controls the emission of carbon monoxide, nitrogen oxides, and unburned gasoline molecules by use of a very complex network of catalytic reactions. This application has contributed more than any other to public awareness of catalysis and of its many applications for the benefit of mankind. RESEARCH OPPORTUNITIES IN CATALYTIC SCIENCE AND TECHNOLOGY For viable commercial application, catalysts of any type—heterogeneous, homogeneous, or enzymatic—must exhibit a number of properties, the principal ones being high activity, selectivity, and durability and, in most cases, regenerability. The activity of a catalyst influences the size of the reactor required to achieve a given level of conversion of reactants, as well as the amount of catalyst required. The higher the catalyst activity, the smaller are the reactor size and the inventory of catalyst and, hence, the lower are the capital and operating costs. High catalyst activity can also permit less severe operating conditions (e.g., temperature and pressure), and this too can result in savings in capital and operating costs. The amount of reactant required to produce a unit of product, the properties of the product, and the amount of energy required to separate the desired product from reactants and by-products are all governed by catalyst selectivity. As a consequence, catalyst selectivity strongly influences the economics of a process. Catalyst productivity and the time on-stream are dictated by catalyst stability. All catalysts undergo a progressive loss in activity and/or selectivity with time due to chemical poisoning, denaturing, thermal deactivation or decomposition, and physical fouling. When the decrease in performance becomes too severe, the catalyst must be either regenerated or replaced. In view of this, high stability and ease of regeneration become important properties. Catalysis is a complex, interdisciplinary science. Therefore, progress toward a substantially improved vision of the chemistry and its practical application depends on parallel advances in several fields, most likely including the synthesis of new catalytic materials and understanding the path of catalytic reactions. For this reason, future research strategies should be focused on developing methods with an ability to observe the catalytic reaction steps in situ or at least the catalytic site at atomic resolution. There is also a need to link heterogeneous catalytic phenomena to the broader knowledge base in solutions and in well-defined metal complexes. Substantial progress and scientific breakthroughs have been made in recent years in several fields, including atomic resolution of metal surfaces,
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Catalysis Looks to the Future in situ observation of an olefin complexed to zeolite acid sites by nuclear magnetic resonance (NMR) spectroscopy, and in situ characterization of several reaction intermediates by a variety of spectroscopic techniques. Theoretical modeling is now ready for substantial growth as a result of progress in computer technology and in theory itself. For these reasons, it is desirable to focus on areas in which the extensive scientific and technological resources of academe and industry may lead to the fastest practical results. In order of priority, these areas are in situ studies of catalytic reactions; characterization of catalytic sites (of actual catalysts) at atomic resolution (metals, oxides); synthesis of new materials that might serve as catalysts or catalyst supports; and theoretical modeling linked to experimental verification. Furthermore, additional steps must be taken to facilitate interaction and, in fact, cooperation between industry, dealing with proprietary catalysts, and academe, developing advanced characterization tools for catalysis. REPORT FINDINGS Catalysis plays a fundamental role in the economy, environment, and the public health of the nation; it underlies several of the critical national technologies identified in the 1991 Report of the National Critical Technologies Panel. Specifically, two of the largest industry segments, chemicals and petroleum processing, depend on catalysis; many of the modern, cost-and energy-efficient environmental technologies are catalytic; and biocatalysis offers exciting opportunities for producing a broad range of pharmaceuticals and specialty chemicals, and for bioremediation of the environment. As opposed to some other areas of technology, the United States still plays a leadership role in catalysis, as evidenced by the general superiority of U.S. petroleum conversion processes and most chemical processes, and by the net positive chemical trade balance of the United States. However, this position is eroding rapidly, due to the heavy investment in R&D of Japan and the European Community. Major opportunities exist for developing new catalytic processes and for advancing the intellectual frontiers of all branches of science pertaining to catalysis. To take advantage of these opportunities, careful attention must be given to effective use of the nation's resources, so that the United States can maintain its leadership role.
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Catalysis Looks to the Future REPORT RECOMMENDATIONS For Industry Industry in the United States is faced with enormously high costs associated with environmental remediation, short-term financial performance, high interest rates, and global competition. At the same time, substantial opportunities exist for developing new processes and products based on still-to-be-discovered catalysts. Therefore, industry should strive for an updated balance between long-and short-range research, aimed at taking advantage of these opportunities. This would be facilitated by long-range business and technology planning; technology forecasting and trend analysis; a more stable commitment to strategic projects, joint development, and joint venture programs with other companies for risk sharing; and high-quality project selection and evaluation methodologies. The challenges faced by industry will require additional advances in the science of catalysis, as well as advances in instrumentation. To better achieve this goal, additional opportunities for developing meaningful collaborative programs in partnership with academic and national laboratory researchers should be pursued. Two elements are recommended as essential: Enhanced appreciation by academic researchers of industrial technology. Vehicles for this include long-term consulting arrangements involving regular interactions with industrial researchers, sabbaticals for industrial scientists in academic or government laboratories, sabbaticals for academic or government scientists in industrial laboratories, industrial internships for students, industrial postdoctoral programs, and jointly organized symposia on topics of industrial interest. Increased industrial support of research at universities and national laboratories. Vehicles for this include research grants and contracts; unrestricted grants for support of new, high-risk initiatives; and leveraged funding (e.g., support of the Presidential Young Investigators program.) For Academic Researchers Academic researchers have made major contributions to the fruitful understanding of the structure of homogeneous, heterogeneous, and enzyme catalysts, and the relationships between structure and function. They have
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Catalysis Looks to the Future also contributed substantially to the development of new instrumental and theoretical techniques, many of which now find application in industrial laboratories. To maintain healthy progress in catalyst science as a basis for future developments in catalyst technology, and to provide an adequate supply of scientists educated in the principles underlying catalysis, the panel recommends, in order of importance, the following: A materials-focused approach is needed to complement the existing strong efforts on understanding and elucidating catalytic phenomena. More emphasis should be placed on investigation of the optimized design and synthesis of new catalytic materials, in addition to the study of existing ones. It must be kept in mind that a new material deserves consideration as a potential catalytic material only after its successful use as a catalyst, or as a component of such. Further advancement should be made in the characterization of catalysts and the elucidation of catalytic processes, particularly under reaction conditions; existing studies of structure-function relationships should be continued and expanded to focus on catalysts relevant to applications with major potential. Academic researchers should develop cooperative, interdisciplinary projects, or instrumental facilities, in which researchers from a range of disciplines work on various aspects of a common goal, as exemplified by programs carried out in NSF-supported Science and Technology Centers. Academic researchers should be encouraged to work collaboratively on projects with industry that are aimed at enabling the development of catalyst technology through the application of basic knowledge of catalysts and catalytic phenomena. Academic institutions should ease their patent policies with respect to ownership and royalties, to facilitate greater industrial support of research. For National Laboratories The national laboratories have been highly effective in developing novel instrumentation for catalyst characterization, operating large-scale user facilities (i.e., synchrotron radiation sources, pulsed neutron sources, and atomic resolution microscopes), and applying the most advanced experimental and theoretical techniques to study structure-function relationships critical for understanding catalysis at the molecular level. Given the wealth of resources at these laboratories, major opportunities exist for advancing catalyst science and technology through research, including work carried
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Catalysis Looks to the Future out in collaboration with industry and academic scientists. The panel encourages the national laboratories to undertake collaborative research with industry focused on developing fundamental understanding of the structure-property relationships of industrially relevant catalysts and catalytic processes, and on using such understanding for the design of important new catalysts; continue the development of novel instrumentation for in situ studies of catalysts and catalytic phenomena; place greater emphasis on the systematic synthesis of new classes of materials of potential interest as catalysts; and investigate novel catalytic approaches to the production of energy, the selective synthesis of commodity and fine chemicals, and the protection of the environment. For the Federal Government The principal sources of support for university and national laboratory research on catalysis are the Department of Energy (DOE) and the National Science Foundation (NSF). As noted in Chapter 4, constant-dollar funding from these agencies, together with inflation and rising overhead costs, has caused a decrease in the number of young scientists being trained in the field of catalysis. The panel also observes that with the decline in emphasis on alternative fuels, research in catalysis has become increasingly diversified and less aligned along national interests. To offest these trends, the panel recommends that federal agencies establish mechanisms for reviewing their programs related to catalysis, to ensure that they are balanced and responsive to the needs of the nation and to the opportunities for accelerating progress; encourage industry to assist the funding agencies in identifying important fundamental problems that must be solved to facilitate the translation of new discoveries into viable products and processes; assessment of the fundamental research needs of industry should be communicated to all members of the catalysis community; and increase the level of federal funding in support of catalysis research by at least a factor of two (after correction for inflation) over the next five years. This recommendation is consistent with the Bush administration's proposal to double the NSF budget over the next five years and with a recent statement by Frank Press, president of the National Academy of Sciences, that doubling the research budgets of all federal agencies
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Catalysis Looks to the Future should be a goal for the 1990s. Recognizing the need for federal agencies to maintain flexibility and to encourage creative scientists who propose to explore new directions and ideas, the panel recommends that priority be given to the following five areas: Synthesis of new catalytic materials and understanding of the relationships between synthesis and catalyst activity, selectivity, and durability. Development of in situ methods for characterizing the composition and structure of catalysts, and structure-function relationships for catalysts and catalytic processes of existing, and potential, industrial interest. Development and application of theoretical methods for predicting the structure and stability of catalysts, as well as the energetics and dynamics of elementary processes occurring during catalysis, and use of this information for the design of novel catalytic cycles and catalytic materials and structures. Investigation of novel catalytic approaches for the production of chemicals and fuels in an environmentally benign fashion, the production of fuels from non-petroleum sources, the catalytic abatement of toxic emissions, and the selective synthesis of enantiomerically pure products. Provision of the instrumentation, computational resources, and infrastructure needed to ensure the cost-effectiveness of the entire research portfolio. This report is intended to identify the research opportunities and challenges for catalysis in the coming decades, to document the achievements and impacts of catalytic technologies—past and still to come, and to detail the resources needed to ensure the continued progress that will enable the United States to remain a world leader in the provision of new catalytic technologies. Chapter 1 provides an introduction to the science and technology of catalysts. Chapter 2 discusses the opportunities for developing new catalysts to meet the demands of the chemical and fuel industries, and the increasing role of catalytic technology in environmental protection. The intellectual challenges for advancing the frontiers of catalytic science are outlined in Chapter 3. The human and institutional resources available in the United States for carrying out research on catalysis are summarized in Chapter 4. The panel's findings and recommendations for industry, academe, the national laboratories, and the federal government are presented in fuller detail in Chapter 5.
Representative terms from entire chapter: