istry suggests that hydrogen would have accounted for about 10 percent of the input mass, or 6 MMT. Most of this was presumably used for other refinery operations, especially hydrogen reforming and hydrogen desulfurization. Some of the input material, mostly gas, was burned to provide energy for the dehydrogenation and cracking furnaces. Again, we have no precise data, but 5 percent (3 MMT) seems a reasonable estimate.

A further 1-2 percent of feedstocks (0.6-1.2 MMT) may have been lost as VOC emissions. Even so, we cannot fully account for the outputs. For example, it is not clear from the data whether natural gas consumed for ammonia production is or is not included. (Urea, made from ammonia, is included as an organic chemical product.) Methanol is certainly one of the primary products, but most methanol is imported, and the domestic product (1.85 MMT in 1988) could not account for very much of the 8.8 MMT of "missing" feedstocks.

To simplify somewhat, we consider the "true" feedstocks to the organic chemical industry to be C2-C5 olefins (33.35 MMT, approximately), aromatics (BTX and naphthalenes, 5.78 MMT, excluding the BTX diverted to gasoline additives), and methanol (4 MMT). The grand total of hydrocarbon feedstocks and methanol appears to have been 43.1 MMT in 1988. Some of this production, especially C4-C5 and higher-order aliphatics, was not actually used to manufacture other chemicals. Some was used as an octane booster in gasoline or as a solvent; some was converted to hydrogen, mostly used in the refining process, or to carbon black.31 However, most downstream synthetic organic chemicals are derived from the above-mentioned sources or the previously discussed inorganic intermediates. Olefins, in particular, are almost immediately and completely converted to polymers or other chemical intermediates such as alcohols and/or resins. In addition, we must account for miscellaneous organics such as glycerol (about 0.25 MMT, derived from animal or vegetable oils), fatty acids from vegetable oils used in liquid-detergent manufacture (0.735 MMT), and soluble cellulose used for cellulose acetate but not rayon (0.5 MMT).32

We also include specified fractions of the major inorganics discussed above. The latter include nitrogen chemicals, chlorine chemicals, sulfuric acid, and sodium hydroxide not used for other purposes and accounted for elsewhere. The last two reagents, in particular, are used in great quantities, but very little of the reactive element in either case is embodied in final products.

As regards chemicals, the situation is confused by imports, exports, and byproducts at various stages. In the case of ammonia, over 90 percent goes to fertilizers, explosives, synthetic fibers, plastics, and other identified inorganics. We can account for 0.737 MMT (N content) embodied in organic chemicals, plus about 0.16 MMT of associated process losses in 1988. So, a total of 0.9 MMT N was consumed in making synthetic organic chemicals in 1988, mainly plastics and fibers. Total weight of ammonia used would therefore have been about 1.1 MMT. For sulfur, the amount embodied in organic products was very small (0.08 MMT), but the amount used dissipatively in the industry was at least 0.6 MMT



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