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Catalysis Looks to the Future
PRODUCTION OF CHEMICALS
In considering new routes to existing products, emphasis here is placed on major advances rather than on incremental improvements, even though the latter are often quite valuable and justified. With the increasing maturity of catalytic technology for most large-volume commodity chemicals, major advances in the future will require technical discontinuities. These discontinuities, as opposed to improvements in existing technologies, offer the real opportunities for catalysis to have an impact on the economy.
One can recognize and identify limits in the current technology for almost all major products made via catalytic processes. Furthermore, in most cases, at least one potential pathway to a major advance can be visualized. Each such advance constitutes a latent opportunity to shift to a lower-cost feedstock or to a simpler, less-capital-intensive route.
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. For example, the Monsanto process for making acetic acid (CH3COOH) via methanol (CH3OH) carbonylation involved a feedstock change—a shift from ethylene (C2H4), used in the previously dominant Wacker process, to methanol (CH3OH). Since its launching in 1970, the Monsanto process has captured most of the world's new capacity for making acetic acid. Feedstock price changes in recent years have further magnified the cost advantage of the methanol carbonylation route.
By far the strongest current thrust toward lower-cost feedstocks is the effort to substitute alkanes (ethane, propane, and butane) for the corresponding olefins and to convert methane to olefins or aromatics. The difference in price between these alkanes and their olefin counterparts can frequently be as much as 10¢ per pound, which is substantial. An excellent example is the production of maleic anhydride, a monomer for specialty plastics. Over the past 40 years, advances in catalytic technology have enabled the industry to switch from high-priced, toxic benzene to butenes and, more recently, to the lower-cost hydrocarbon butane. This latter development was possible only as a result of the discovery of the vanadyl phos-