Carbon feedstocks

These observations consummated in a growth model that confers on the millions of aligned zone 1 nanotubes the role of field emitters, a role they play so effectively that they are the dominant source of electron injection into the plasma. In response, the plasma structure, in which current flow becomes concentrated above zone 1, enhances and sustains the growth of the field emission source —that is, zone 1 nanotubes. A convection cell is set up in order to allow the inert helium gas, which is swept down by collisions with carbon ions toward zone 1, to return to the plasma. The helium flow carries unreacted carbon feedstock out of zone 1, where it can add to the growing zone 2 nanotubes. In the model, it is the size and spacing of these convection cells in the plasma that determine the spacing of the zone 1 columns in a hexagonal lattice. 

The alternative fuels and drive systems available only seem to be viable on the mass market, if the oil price stays above 60 to 70 /bbl for a sustained period. Oil prices peaked above 140 /bbl in summer 2008 and many experts believe that stable oil prices over 100 /bbl could be reached in the next one or two decades. The higher the market prices of fossil fuels, the more competitive low-carbon alternatives will become The principal choice here is between biofuels, electricity and hydrogen, provided that they are produced either from low/zero-carbon feedstock or that the C02 generated during their production is captured and stored. But higher priced conventional oil resources, on the other hand, can also be replaced by high-carbon alternatives such as oil sands, oil shale or synthetic fuels from coal and gas. 

The conversion of carbon dioxide into carbon feedstock for the manufacture of fuels and chemicals is an important area of research. It has the advantage of lower cost, due to the abundant supply of CO, and has the environmental benefit of... 

Vegetable oils represent only 5% of the renewable resources available. Today, vegetable oils currently provide a marginal carbon feedstock contribution to the chemical industry in such applications as solvents, surfactants, and lubricants. Vegetable oils may, however, play a much more important role in the future. They are mixtures of fatty acid trigclycerides whose typical molecular structures are given in Figure 10.12. 

The major one-carbon feedstock is methane and it serves as the feedstock to a number of important monomers including hexamethylene tetramine and melamine, used in the synthesis of a number of cross-linked thermosets as well as vinyl acetate, ethylene, ethylene glycol, and methyl methacrylate (Table 17.1). 

One major two-carbon feedstock is ethylene. From Figure 17.2, you can see that a number of the monomers are directly synthesized from ethylene. Again, while the react arrow goes directly from ethylene to the product, as noted earlier, it often takes years to develop an economical procedure to obtain the product in essentially 100% yield. Here, depending on the reaction conditions, a wide variety of intermediates and products are formed, which allow... 

Another two-carbon feedstock is acetylene. Acetylene is typically obtained from coal by converting coke calcium carbide and then treating the calcium carbide with water. As shown in Figure 17.3, a number of important monomers can be made from acetylene. Even so, because of the abundance of other feedstocks from petroleum reserves, only some of the routes shown in Figure 17.3 are widely used. 

The major four-carbon feedstock molecules are 1,3-butadiene and isobutylene, both involved in the synthesis of many monomers and intermediates. Butadiene is copolymerized with styrene to form SBR and with acrylonitrile to form ABS rubbers. 

The abundance and nontoxic nature of carbon dioxide also make it an attractive carbon feedstock. Potential sources of carbon dioxide include the atmosphere (where it is present in concentrations of approximately 370 ppm), natural reservoirs including natural gas wells and pure CO2 wells, waste streams of fermentation reactions, and flue stacks from power plants, cement production, and so on. Because CO2 is not toxic, development of chemical processes in which CO2 can be used to... 

In the process, the carbon feedstock is calcined (1250°C) to volatilize any impurities, after which the calcined products are ground, screened, weighed, mixed with binder, formed by molding or extrusion into green electrodes, and arranged in the furnace (Fig. 4). 

Navarro RM, Pena MA, Fierro JLG. Hydrogen production reactions from carbon feedstocks fossils fuels and biomass. Chem Rev. 2007 107(10) 3952-91. 

The FTS converts synthesis gas into mostly liquid hydrocarbons [12-15]. Depending on the origin of the synthesis gas, the overall process from carbon feedstock to liquid product is called gas-to-liquids (GTL), coal to liquids (CTL), or biomass to liquids (BTL). The product spectrum, however, is broader than liquid hydrocarbons alone and can include methane and alkanes, C H2 +2 (with n from 1 — 100), alkenes or olefins (C H2 n > 2), and to a lesser extent, oxygenated products such as alcohols. Hence the FTS offers the opportunity to convert gas, coal, or biomass-derived syngas into transportation fuels, such as gasoline, jet fuel, and diesel oil, and chemicals, such as olefins, naphtha, and waxes. The reactions need a catalyst, which in commercial applications is either based on cobalt or iron. 

Company Location Carbon feedstock Catalyst type Reactor type Start-up date capacity (barrel per day)... 

First, a hydrocarbon or a carboneous feedstock, water and air are converted to synthesis gas consisting of hydrogen and nitrogen in a 3 to 1 volumetric ratio. The second step in the process is ammonia synthesis according to the following well-known reaction ... 

Carbonylation (the addition of carbon monoxide to organic molecules) is an important industr process as carbon monoxide is a convenient one-carbon feedstock and the resulting metal-acyl cor plexes can be converted into aldehydes, acids, and their derivatives. The 0X0 process is the hydr formylation of alkenes such as propene and uses two migratory insertions to make higher val aldehydes. Though a mixture is formed this is acceptable from very cheap starting materials. 

A catalytic decomposition of carbon feedstock under a controlled environment at high temperature (>900 °C) produces carbon nanotubes. The CVD technique is one of the widely used techniques for the synthesis of both MWNTs and SWNTs. A hydrocarbon feedstock is used as the carbon source that is catalytically decomposed to form reactive carbon vapors. Ethylene and acetylene are used as carbon feedstocks at 550-750 °C in many CVD techniques. There are many different metals that can be used as catalysts to produce... 

Note By-products include mineral impurities in the carbon feedstock that become... 

A number of carbon feedstocks can be used as the carbon source, with the most common being coal, methane, or by-products/tails from the petrochemical industry. Since gasification occurs in an environment with a shortage of oxygen (reducing),... 

Low-value carbon materials with environmental issues are easily utilized as a carbon feedstock. 

The commercial production of H2 typically involves one of the following processes (1) steam reforming, (2) water shift gas reaction, (3) partial oxidation, or (4) autothermal reforming. Electrolysis of water could be used to make H2, but process economics are high when compared to the others processes listed for that reason, electrolysis of water is not included. Currently, the production of H2 by steam reforming has the lowest production cost of any process and is the most widely used, but as mentioned earlier, the cost and availability of the carbon feedstock may change that production cost in the future. ... 

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