Feedstock imported

A detailed study of the properties of the potential products is of prime technical and economic importance, because it allows the refiner to have a choice in selecting feedstocks for his different units for separation, transformation and conversion, to set their operating conditions, in order to satisfy the needs of the marketplace in the best ways possible. 

Ethanol. Accurate projections of ethanol costs are much more difficult to make than are those for methanol. Large scale ethanol production would impact upon food costs and have important environmental consequences that are rarely cost-analyzed because of the complexity. Furthermore, for corn, the most likely large-scale feedstock, ethanol costs are strongly influenced by the credit assigned to the protein by-product remaining after the starch has been removed and converted to ethanol. 

Higher aliphatic alcohols (C —C g) are produced ia a number of important industrial processes using petroleum-based raw materials. These processes are summarized in Table 1, as are the principal synthetic products and most important feedstocks (qv). Worldwide capacity for all higher alcohols was approximately 5.3 million metric tons per annum in early 1990, 90% of which was petroleum-derived. Table 2 Hsts the major higher aliphatic alcohol producers in the world in early 1990. 

Many valuable chemicals can be recovered from the volatile fractions produced in coke ovens. Eor many years coal tar was the primary source for chemicals such as naphthalene [91-20-3] anthracene [120-12-7] and other aromatic and heterocycHc hydrocarbons. The routes to production of important coal-tar derivatives are shown in Eigure 1. Much of the production of these chemicals, especially tar bases such as the pyridines and picolines, is based on synthesis from petroleum feedstocks. Nevertheless, a number of important materials continue to be derived from coal tar. 

Production of Eastman s entire acetic anhydride requirement from coal allows a reduction of 190,000 m /yr (1.2 million barrels/yr) in the amount of petroleum used for production of Eastman chemicals. Now virtually all of Eastman s acetyl products are made in part from coal-based feedstocks. Before the technology was introduced, these chemicals had been made from petroleum-based acetaldehyde. Reduced dependence on petroleum, much of which must be obtained from foreign sources, is important to maintain a strong domestic chemical industry. 

Liquid-phase oxidation of lower hydrocarbons has for many years been an important route to acetic acid [64-19-7]. In the United States, butane has been the preferred feedstock, whereas ia Europe naphtha has been used. Formic acid is a coproduct of such processes. Between 0.05 and 0.25 tons of formic acid are produced for every ton of acetic acid. The reaction product is a highly complex mixture, and a number of distillation steps are required to isolate the products and to recycle the iatermediates. The purification of the formic acid requires the use of a2eotropiag agents (24). Siace the early 1980s hydrocarbon oxidation routes to acetic acid have decliaed somewhat ia importance owiag to the development of the rhodium-cataly2ed route from CO and methanol (see Acetic acid). 

The hquid remaining after the solvent has been recovered is a heavy residual fuel called solvent-refined coal, containing less than 0.8 wt % sulfur and 0.1 wt % ash. It melts at ca 177°C and has a heating value of ca 37 MJ/kg (16,000 Btu/lb), regardless of the quaUty of the coal feedstock. The activity of the solvent is apparently more important than the action of gaseous hydrogen ia this type of uncatalyzed hydrogenation. Research has been directed to the use of petroleum-derived aromatic oils as start-up solvents (118). 

Natural gas Hquids represent a significant source of feedstocks for the production of important chemical building blocks that form the basis for many commercial and iadustrial products. Ethyleae (qv) is produced by steam-crackiag the ethane and propane fractions obtained from natural gas, and the butane fraction can be catalyticaHy dehydrogenated to yield 1,3-butadiene, a compound used ia the preparatioa of many polymers (see Butadiene). The / -butane fractioa can also be used as a feedstock ia the manufacture of MTBE. 

A considerable amount of carbon is formed in the reactor in an arc process, but this can be gready reduced by using an auxiUary gas as a heat carrier. Hydrogen is a most suitable vehicle because of its abiUty to dissociate into very mobile reactive atoms. This type of processing is referred to as a plasma process and it has been developed to industrial scale, eg, the Hoechst WLP process. A very important feature of a plasma process is its abiUty to produce acetylene from heavy feedstocks (even from cmde oil), without the excessive carbon formation of a straight arc process. The speed of mixing plasma and feedstock is critical (6). 

Much more important is the hydrogenation product of butynediol, 1,4-butanediol [110-63-4]. The intermediate 2-butene-l,4-diol is also commercially available but has found few uses. 1,4-Butanediol, however, is used widely in polyurethanes and is of increasing interest for the preparation of thermoplastic polyesters, especially the terephthalate. Butanediol is also used as the starting material for a further series of chemicals including tetrahydrofuran, y-butyrolactone, 2-pyrrohdinone, A/-methylpyrrohdinone, and A/-vinylpyrrohdinone (see Acetylene-DERIVED chemicals). The 1,4-butanediol market essentially represents the only growing demand for acetylene as a feedstock. This demand is reported (34) as growing from 54,000 metric tons of acetylene in 1989 to a projected level of 88,000 metric tons in 1994. 

Production of maleic anhydride by oxidation of / -butane represents one of butane s largest markets. Butane and LPG are also used as feedstocks for ethylene production by thermal cracking. A relatively new use for butane of growing importance is isomerization to isobutane, followed by dehydrogenation to isobutylene for use in MTBE synthesis. Smaller chemical uses include production of acetic acid and by-products. Methyl ethyl ketone (MEK) is the principal by-product, though small amounts of formic, propionic, and butyric acid are also produced. / -Butane is also used as a solvent in Hquid—Hquid extraction of heavy oils in a deasphalting process. 

Applications. The most ubiquitous use of infrared spectrometry is chemical identification. It has long been an important tool for studying newly synthesi2ed compounds in the research lab, but industrial identification uses cover an even wider range. In many industries ir spectrometry is used to assay feedstocks (qv). In the flavors (see Flavors and spices), fragrances (see Perfumes), and cosmetics (qv) industries, it can be used not only for gross identification of feedstocks, but for determining specific sources. The spectra of essential oils (see Oils, essential), essences, and other natural products vary with the season and source. Adulteration and dilution can also be identified. 

Improved feedstock pretreatment is important to minimize catalyst consumption and reduce subsequent spent-catalyst handling requirements. Selective hydrogenation of dienes can be used to reduce acid consumption, both in HF and H2SO4 alkylation (29). More effective adsorptive treating systems have been appHed to remove oxygen-containing contaminants that are frequently introduced in upstream processing steps. 

Steam-Reforming Natural Gas. Natural gas is the single most common raw material for the manufacture of ammonia. A typical flow sheet for a high capacity single-train ammonia plant is iadicated ia Figure 12. The important process steps are feedstock purification, primary and secondary reforming, shift conversion, carbon dioxide removal, synthesis gas purification, ammonia synthesis, and recovery. 

The separation train of the plant is designed to recover important constituents present in the furnace effluent. The modem olefin plant must be designed to accommodate various feedstocks, ie, it usually is designed for feedstock flexibiUty in both the pyrolysis furnaces and the separation system (52). For example, a plant may crack feedstocks ranging from ethane to naphtha or naphtha to gas oils. 

The quahty of sulfonic acids produced as iatermediates on an iadustrial scale is important to detergent manufacturers. Parameters such as color, water, free oil (unsulfonated material), and acid value (actual sulfonic acid) are all factors that determine the quaUty of a sulfonic acid. The quaUty of the feedstock prior to sulfonation, such as iodine value, water content, and sulfonatabiUty, affects the quaUty of the sulfonic acid produced. Sulfonation conditions, such as temperature, molar ratio, rate, etc, also affect the quaUty of sulfonic acid. 

Environmental profile has been and will continue to be an important determinant of a market acceptability of surfactants, but will not guarantee its success (111—113). Price and availability have been primary determinants of hydrophobe choice for alcohol-based feedstocks (114). 

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