Sustainable 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. 

Short (in balance) sustainable carbon cycle using bio-based carbon feedstock MATERIAL CARBON FOOTPRINT... 

However, if we use annually renewable crops or biomass as the feedstocks for manufacturing our carbon based polymers, chemicals, and fuels, the rate at which CO2 is fixed equals the rate at which it is consumed and liberated - this is sustainable and the use of annually renewable crops/biomass would allows us to manage carbon in a sustainable manner. Furthermore, if we manage our biomass resources effectively by making sure that we plant more biomass (trees, crops) than we utilize, we can begin to start reversing the CO2 rate equation and move towards a net balance between CO2 fixation/sequestration and release due to consumption. Thus, using annually renewable carbon feedstocks allows for ... 

It should be pointed out that the raw materials for VAM and its related polymers (i.e. ethylene and acetic acid) are produced from fossil resources, mainly crude oil. It is possible to completely substitute the feedstock for these raw materials and switch to ethanol, which can be produced from renewable resources like sugar cane, com, or preferably straw and other non-food parts of plants. Having that in mind, the whole production of PVAc, that nowadays is based on traditional fossil resources, could be switched to a renewable, sustainable and C02-neutral production process based on bioethanol, as shown in Fig. 3. If the vinyl acetate circle can be closed by the important steps of biodegradation or hydrolysis and biodegradation of vinyl ester-based polymers back to carbon dioxide, then a tmly sustainable material circle can be established. 

The sustained elevated price of crude oil seen in 2005 has led to increased interest in synthetic fuels. Synthetic fuels have been produced for more than 80 years through processes known as Fischer-Tropsch chemistry. Carbon monoxide is a basic feedstock in these processes. Franz Fischer (1852-1932) and Hans Tropsch (1889-1935) produced liquid hydrocarbons in the 1920s by reacting carbon monoxide (produced from natural gas) with hydrogen using metal catalysts such as iron and cobalt. Germany and Japan produced synthetic fuels during World War II. Low crude oil prices dictated little interest in synthetic fuels after the war,... 

The ultimate in sustainable catalytic processes is the integration of chemocat-alytic and/or biocatalytic steps into catalytic cascade processes that emulate the metabolic pathways of the cell factory. It is an esthetically pleasing thought that, in the future, fuels, chemicals and polymers could be obtained from carbon dioxide and water as the basic raw materials via biomass, using sunlight as the external source of energy and water and supercritical carbon dioxide as solvents. The important difference between this bio-based scenario and the current oil-based one is the time required for renewal of the feedstocks. 

Biomass as feedstock to syngas K. Tomishige, M. Asadullah, and K. Kuni-mori, Catalysis Today 2004, 89, 389 M. Rohde, D. Unruh, P. Pias, K-W. Lee, and G. Schaub, Studies in Surface Science and Catalysis 2004, 153 (Carbon Dioxide Utilization for Global Sustainability), 97. 

The relative performance of biomass energy systems in reducing net greenhouse gas emissions depends on the sustainability of the sources of biomass feedstock, the energy requirements of the conversion systems, and the overall conversion efficiencies. Unlike fossil fuels, biomass production systems recapture emissions of carbon dioxide. It has been well documented that... 

The fact that menthol is produced from both renewable and fossil feedstocks allows for an interesting study in sustainability. In order to produce the same crop year after year, it is necessary to use fertilisers to replenish the nitrogen and minerals which the plant takes from the soil. Secondary metabolites such as menthol and essential oils occur at a level of, at most, only a few per cent of the dry weight of the herb. Therefore, in order to produce an economic return, it is necessary to use efficient, mechanical methods of cultivation and harvesting. A full life cycle analysis of menthol production reveals that production from cultivation of mint plants consumes more fossil fuel, produces more carbon dioxide effluent and has more environmental impact than either of the leading synthetic routes. 

New methods for improving the sustainability of the methane thermocatalytic decomposition process have been developed. Studies indicate that the presence of small amounts of moisture and H2S (<3 v.%) in the hydrocarbon feedstock is not detrimental for the catalyst activity and process efficiency. This implies that commercial hydrocarbon fuels could potentially be employed as feedstocks for the process. A bench-scale thermocatalytic reactor was designed, fabricated and operated using methane and propane as feedstocks. The TCR produced hydrogen-rich gas free of CO/CO2 impurities the gas was directly fed to PEM fuel cell. Material characterization studies indicated that depending on operational conditions, carbon could be produced in several valuable forms including turbostratic carbon, pyrolytic graphite, spherical carbon particles, or filamentous carbon. 

Part E discusses the use of microorganisms as novel sustainable feedstocks in industrial biotechnology. Chapter 14 sheds light on thermophilic bacteria, whereas Chapters 15 and 16 deal with autotrophic systems that enable production simply from sunlight and carbon dioxide cyanobacteria and algae. 

The first part of this chapter is intended to survey recent literature on new catalytic materials because the development of new types of metal oxides and layered- and carbon-based materials with different morphologies opens up novel acid-base catalysis that enables new type of clean reaction technologies. Mechanistic considerations of acid- and base-catalyzed reactions should result in new clean catalytic processes for Green and Sustainable Chemistry, for example, transformations of biorenewable feedstock into value-added chemicals and fuels [21-35]. The latter part of this chapter, therefore, focuses on biomass conversion using solid acid and base catalysts, which covers recent developments on acid-base, one-pot reaction systems for carbon-carbon bond formations, and biomass conversion including synthesis of furfurals from sugars, biodiesel production, and glycerol utilization. 

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