9727137 McConica The chemical industry frequently deals with hazardous chemicals by adopting alternative technologies that avoid the use of such raw materials. This is an attractive strategy, but it is not universally applicable. The alternative processes can be major generators of environmentally-harmful waste, and can involve materials that are only marginally less hazardous. Thus, other options are needed. This proposal examines a novel approach to the problem of using reactive and hazardous chemicals: in- situ generation. Successful development of this concept will create important new options in the area of environ- mentally-benign chemical synthesis. Formaldehyde is an example of a hazardous and costly chemical that has traditionally been avoided in chemical synthesis. It is a suspected or probable' man carcinogen, and it is so reactive that it cannot be stored or shipped in pure form. However, a number of important chemicals could be produced with much less pollution and with greater safety via formaldehyde than by their current commercial processes. For example, substitution of formaldehyde-based processes for the technologies currently used to produce methyl methacrylate and styrene could eliminate the use of about 8 billion pounds of benzene and about 250 million pounds of hydrogen cyanide annually, and could eliminate about 1 billion pounds of ammonium bisulfate waste and about 100 million pounds of aluminum trichloride waste annually, in the United States alone. The recent development of high-temperature slurry reactors in our laboratory, coupled with steady progress in the catalysis and reaction engineering of polystep reactions, permits a new approach to utilization of hazardous chemicals. In essence, the hazardous chemical will be generated and consumed in situ in a single reactor. For example, it is known that formaldehyde can react with methyl propionate over various heterogeneous catalysts in the temperature range of 300 to 400' C to form methyl methacrylate. It should be possible to simultaneously dehydrogenate methanol to formaldehyde in the same reactor, using a different catalyst. The coupling of these two reactions would result in the synthesis of methyl methacrylate from methanol and methyl propionate. Similarly, styrene could be synthesized from methanol and toluene. The key is to employ a slurry reactor containing a physical mixture of a methanol dehydrogenation catalyst and a catalyst for the formaldehyde-consuming reaction, with the rates of the two reactions properly balanced. This research will focus on in-situ formaldehyde generation, i.e., the dehydrogenation of methanol to formaldehyde, in a high-temperature slurry reactor. Emphasis will be placed on understanding the effect of catalyst composition and structure, and the reactor design and operating variables, on the kinetics and selectivity of the reaction. This knowledge will provide a sound fundamental basis for coupling in-situ formaldehyde generation with various formaldehyde-consuming reactions. The proposed research program has the potential to produce a major advance in environmentally-benign chemical synthesis, since the novel concept of in-situ generation should have broad applicability as an enabling technology for process substitution. The proposed research will also provide an important scientific advance, i.e., a more fundamental basis for the a priori design of catalyst systems for polystep reactions in slurry reactors. ***
