Feedstock economics

In addition to detergency performance and feedstock economics, other factors related to the processing of these powder formulations must be considered, such as sulfonation/sulfation, crutcher slurry preparation, and spray drying. AS and AES are thermally and hydrolytically less stable than LAS. Care must be taken in spray drying to avoid decomposition and pluming problems. This may place a limitation on the levels of AS and AES in spray-dried laundry powders. 

For reasons of performance, feedstock economics, and processing versatility, LAS will continue in the future to be a major component of mixed active detergent products. 

The second chemical goal for sustainability that Collins presented was renewable feedstocks. Economical feedstocks for chemical and polymer industries from plants are needed. 

TABLE 22.4 Feedstock Economics for Ammonia Production Relative Consumptions and Economics for Different Feedstocks... 

Integrated environmental education exploiting natural remediation process agricultural as a closed system development of renewable energy sources development of renewable chemical feedstocks economically mimicking natural... 

The discovery of new technology to manufacture ethylene from other raw materials could also change the feedstock economics for the manufacture of polyethylene. Two such possibilities are manufacturing ethylene from (a) methane or methanol, or (b) biomass material. New scientific discoveries would be needed to facilitate such a change. 

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. 

A comparison of overall treatment costs (purchase and refining) for several crude oils enables the refiner to establish his feedstock requirements and to satisfy the market needs under the most economical conditions. 

Cost. It is necessary to produce the feedstock from which the monomer is generated, viz, the dimer, at a cost which can be supported by the commercial appHcation, and yet allow it to be economically competitive with all other alternative ways to achieve the same end result. This factor often, but not always, seriously limits the amount of effort that can be put iato dimer synthesis and purification. 

Since 1960, the Hquid-phase oxidation of ethylene has been the process of choice for the manufacture of acetaldehyde. There is, however, stiU some commercial production by the partial oxidation of ethyl alcohol and hydration of acetylene. The economics of the various processes are strongly dependent on the prices of the feedstocks. Acetaldehyde is also formed as a coproduct in the high temperature oxidation of butane. A more recently developed rhodium catalyzed process produces acetaldehyde from synthesis gas as a coproduct with ethyl alcohol and acetic acid (83—94). 

Olefin Sources. The choice of feedstock depends on the alcohol product properties desired, availabiUty of the olefin, and economics. A given producer may either process different olefins for different products or change feedstock for the same appHcation. Feedstocks beheved to be currentiy available are as follows. 

Coal is used ia industry both as a fuel and ia much lower volume as a source of chemicals. In this respect it is like petroleum and natural gas whose consumption also is heavily dominated by fuel use. Coal was once the principal feedstock for chemical production, but ia the 1950s it became more economical to obtain most industrial chemicals from petroleum and gas. Nevertheless, certain chemicals continue to be obtained from coal by traditional routes, and an interest in coal-based chemicals has been maintained in academic and industrial research laboratories. Much of the recent activity in coal conversion has been focused on production of synthetic fuels, but significant progress also has been made on use of coal as a chemical feedstock (see Coal CONVERSION processes). 

In 1991, the relatively old and small synthetic fuel production faciHties at Sasol One began a transformation to a higher value chemical production facihty (38). This move came as a result of declining economics for synthetic fuel production from synthesis gas at this location. The new faciHties installed in this conversion will expand production of high value Arge waxes and paraffins to 123,000 t/yr in 1993. Also, a new faciHty for production of 240,00 t/yr of ammonia will be added. The complex will continue to produce ethylene and process feedstock from other Sasol plants to produce alcohols and higher phenols. 

ElexibiHty allows the operator to pick and choose the most attractive feedstock available at a given point in time. The steam-cracking process produces not only ethylene, but other products as weU, such as propylene, butadiene, butylenes (a mixture of monounsaturated C-4 hydrocarbons), aromatics, etc. With ethane feedstock, only minimal quantities of other products ate produced. As the feedstocks become heavier (ie, as measured by higher molecular weights and boiling points), increasing quantities of other products are produced. The values of these other coproduced products affect the economic attractiveness and hence the choice of feedstock. 

Olefin Feedstock Selection. The selection of feedstock and severity of the cracking process are economic choices, given that the specific plant has flexibiUty to accommodate alternative feedstocks. The feedstock prices are driven primarily by energy markets and secondarily by supply and demand conditions ia the olefins feedstock markets. The prices of iadividual feedstocks vary widely from time to time as shown ia Figure 2, which presents quarterly prices of the various feedstocks ia the United States from 1978 through 1991 ia dollars per metric ton (1000 kg) (4). 

Alternative feedstocks for petrochemicals have been the subject of much research and study over the past several decades, but have not yet become economically attractive. Chemical producers are expected to continue to use fossil fuels for energy and feedstock needs for the next 75 years. The most promising sources which have received the most attention include coal, tar sands, oil shale, and biomass. Near-term advances ia coal-gasification technology offer the greatest potential to replace oil- and gas-based feedstocks ia selected appHcations (10) (see Feedstocks, coal chemicals). 

Cyclization. Constmction of ben2otrifluorides from aHphatic feedstocks represents a new technique with economic potential. For example, l,l,l-trichloro-2,2,2-trifluoroethane [354-58-5] and dimethyl itaconate [617-52-7] form 4-methoxy-6-trifluoromethyl-2JT-pyran-2-one [101640-70-4] which is converted to methyl 3-(trifluoromethyi)ben2oate [2557-13-3] ixh. acetjdene or norbomadiene (125). 

There is an inherent economic penalty associated with producing Hquids from either natural gas or soHd coal feedstock. Synthetic Hquid fuels technologies are generally not economically competitive with cmde oil processing in the absence of extraneous influences such as price supports or regulations. 

There are some chemicals that can be made economically from coal or coal-derived substances. Methanol and CO are used to make acetic anhydride and acetic acid. Methanol itself can be made from synthesis gas over a copper-2inc catalyst (see Feedstocks, coal chemicals). 

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