Catalysis Looks to the Future (1992) / Chapter Skim
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2 NEW OPPORTUNITIES IN CATALYTIC TECHNOLOGY
2 NEW OPPORTUNITIES IN CATALYTIC TECHNOLOGY
Pages 18-42
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Industrial Outlook 1991. 4Report of the National Critical Technologies Panel, William D
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Concern with the environment and the supply of raw materials is also focusing attention on the opportunities for recycling. Of particular interest for the chemical industry is the prospect of producing polymers that are readily recyclable.
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(Figure courtesy of Union Carbide Corporation.) methane, shale, and coal into [quid Gels al an acceptable CosL Also, lo maintain economic competitiveness, it It be necessary to shin to lowercost ~cdslocks for the production of commodity and fine chemicals Taken together, these farces provide ~ strong incentive for increasing research ewes aimed at the discovery of novel catalysts and catalytic processes.
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Lower-Cost Feedstocks For typical commodity chemical processes, feedstock constitutes about 60-70% of the total manufacturing cost. Thus, a great financial impact can result from moving to a lower-cost feedstock.
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An extensive worldwide effort is now under way to develop the catalytic oxidative coupling of methane to petrochemicals as well as liquid fuels. This effort encompasses oxidative coupling of methane to ethylene or aromatics, oxidative methylation of toluene to ethylbenzene and styrene, oxi dative methylation of propylene to C4 olefins, and dehydrogenative coupling of methane to aromatics.
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One great challenge for catalysis has been the possibility of producing ethylene glycol via the oxidative coupling of methanol rather than the standard process based on ethylene as feedstock. Significant progress has been made recently in the catalytic oxidative dimerization of dimethyl ether to dimethoxyethane.
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In addition to the desired partial oxidation products, significant quantities of carbon monoxide, carbon dioxide, and water are often obtained. This results in complex and costly separations that, in turn, lead to processes with unusually high capital intensity.
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The potential impact of catalysis on new products is illustrated in the areas of polymers, pharmaceuticals, and biologically derived products. Polymers The production of raw polymers (e.g., pellets)
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ad ..,.~,, i.,.
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(Figure courtesy of E
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Improved catalysts for creating monomers from agricultural commodities or waste materials offer increasingly important opportunities. This field could benefit from the genetic engineering of specific enzyme "catalysts." Oxidative coupling of methanol to ethylene glycol and ethanol to 1,4-butanediol could open new routes to these important monomers.
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Cationic polymerization continues to be an area of increasing research made possible by improved Lewis or Br0nsted acid catalysis. Continued improvement is desired to yield higher molecular weights and industrially acceptable process conditions.
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The reactions are typically selective with extremely high yields, and enzymes can be used to catalyze a whole sequence of reactions in a single reactor, resulting in vastly improved overall yields with high positional specificity and 100% chiral synthesis in most cases. The improved use of enzyme catalyst technology with whole-cell catalysis, reactions catalyzed by single enzymes, and mixed enzymatic and chemical syntheses are all important for the development of new catalyst technology.
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A patent was recently issued for a genetically engineered Escherichia cold that synthesizes the molecule D-biotin directly from glucose. Biotin has three chiral centers, and the current chemical synthesis requires 13-14 steps with low yields.
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The catalytic cracking process has been the workhorse of modern refineries for 30 years and, with improved catalysts, will continue to be the main process for converting the heavier end of crude oil into more environmentally acceptable components for gasoline and diesel fuels. Oxygenates for Octane Boosting The need to remove aromatics from gasoline has created a need for organic oxygenates as replacement octane enhancers.
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The process technology leading to the majority of oxygenates now in use has been made very efficient through catalyst modifications and engineering design. However, new processes leading to the same oxygenates may have cost advantages if different building blocks and feedstock sources (crude oil versus coal versus natural gas)
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It would provide an economically competitive and convenient source of CO or H2, especially on a small scale, and could be used in chemical plants, materials processing plants, and fuel cells on board a vehicle. Because of these emerging applications, there is renewed interest in developing methanol dissociation technology.
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. The alkylation process is assuming increasing importance with increased olefin production from modern fluid catalytic cracking units and with recent emphasis on clean fuels of lower aromatics content.
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Thus, novel catalysis will in many cases be the critical technology that enables us to retain most of the benefits created by the chemical and petroleum industries, but with improved preservation of the environment. Catalysts for automotive emission control are now well developed in the United States and, in general, meet mandated standards for removal of hydrocarbons, CO, and NOX.
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The abatement of NOx from power plants is important in efforts to control acid rain and photochemical smog, the latter being linked
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. Major improvements in SCR catalyst performance can be achieved through strategic design of the catalyst pore structure.
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The ability of enzymes to degrade natural organics such as the components of gasoline, crude oil, and most solvents, as well as synthetic organics such as trichloroethylene or polychlorinated biphenyls, means that most, if not all, organic contaminants can be degraded in reactions catalyzed by enzymes. Chlorinated organics such as dichlorodiphenyl/trichloroethane and its by-product dichlorodiphenyl ethylene, pentachlorophenol, chlorocatechols, and other chlorinated aromatics used as preservatives and pesticides are degraded in oxidation reactions catalyzed by enzymes from bacteria and other microorganisms.
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growth are mete ~Micmorgani~sms~,~..need water, certain inorganic nutri-'~"~ ents, a'nd sometimes Virgo ~live, bu"t~...once furnished with those staples, 'they Swirl obligingly break down mai~'y~of the synthetic organic ~ chem~i- 'I ~,~ cals mankind, has created,. used, and discarded.
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Enzyme recruitment permits microorganisms to degrade new molecules and broadens the ability of microorganisms to attack synthetic organic chemicals. The idea of using enzymes that can reproduce themselves, can be made very cheaply, and can work under conditions that are often found in the environment may be one of the most effective means modern science can devise for treating and degrading hazardous waste, including organic chemicals synthesized by man to be stable under harsh conditions.
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