Alternative feedstocks

Coal is expected to be the best domestic feedstock alternative to natural gas. Although coal-based ammonia plants have been built elsewhere, there is no such plant in the United States. Pilot-scale projects have demonstrated effective ammonia-from-coal technology (102). The cost of ammonia production can be anticipated to increase, lea ding to increases in the cost of producing nitrogen fertilizers. 

Conference on Chemical Feedstocks Alternatives, American Institute of Chemical Engineers and National Science Foundation, Houston, Texas, October 2-5, 1977. 

Annex 1 Alkane Feedstocks. Alternative Routes to Acetic Acid and Acrylonitrile... 

The production of biodiesel can occur using a variety of feedstocks. Alternative sources can be other oilseeds, tropical oils, waste oils, and animal fat. Soybean oil is plentiful and relatively inexpensive because it is a by-product of soybean meal production. In this way, it makes sense for the early stages of bioenergy development in the United States to use readily available soybean oil supplies and the associated... 

Investigate the use of renewable feedstock alternatives to petroleum. Conclusion... 

Carlsson, A.S., 2009. Plant oils as feedstock alternatives to petroleum — a short survey of potential oil crop platforms. Biochemie 91, 665-670. 

As an alternative to the ratios ni/n2 and [Mi]/[M2] in Eq. (7.15), it is convenient to describe the composition of both the polymer and the feedstock in terms of the mole fraction of each monomer. Defining F as the mole fraction of the ith component in the polymer and fj as the mole fraction of component i in the monomer solution, we observe that... 

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. 

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). 

Because oil and gas ate not renewable resources, at some point in time alternative feedstocks will become attractive however, this point appears to be fat in the future. Of the alternatives, only biomass is a renewable resource (see Fuels frombiomass). The only chemical produced from biomass in commercial quantities at the present time is ethanol by fermentation. The cost of ethanol from biomass is not yet competitive with synthetically produced ethanol from ethylene. Ethanol (qv) can be converted into a number of petrochemical derivatives and could become a significant source. 

The potential of natural gas, which typically has 85—95% methane, has been recognized as a plentiful and clean alternative feedstock to cmde oil (see Gas,natural). Estimates (1 3) place worldwide natural gas reserves at ca 1 x (3.5 x 10 ft ) corresponding to the energy equivalent of ca... 

United States. The demand for acetylene generally peaked between 1965 and 1970, then declined dramatically until the early 1980s, and has been slowly increasing at between 2 and 4% per year since. The dramatic decline was related to increased availabiHty of low cost ethylene, an alternative feedstock for many chemicals, and the recent increase is due to the modest growth of acetylenic chemicals, particularly 1,4-butanediol. 

It is difficult to indicate a representative price for acetylene because it is generally produced either for captive use or on contract. The price seems to be dictated mainly by the price movement of ethylene, often a coproduct as well as an alternative feedstock competing with acetylene. That is, in 1981 when ethylene was 0.55 per kg, acetylene was 1.12 per kg and when in 1987 the price of ethylene dropped to 0.31 per kg, acetylene dropped to 0.68 per kg. 

This excess hydrogen is normally carried forward to be compressed into the synthesis loop, from which it is ultimately purged as fuel. Addition of by-product CO2 where available may be advantageous in that it serves to adjust the reformed gas to a more stoichiometric composition gas for methanol production, which results in a decrease in natural gas consumption (8). Carbon-rich off-gases from other sources, such as acetylene units, can also be used to provide supplemental synthesis gas. Alternatively, the hydrogen-rich purge gas can be an attractive feedstock for ammonia production (9). 

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