Partial Combustion of Hydrocarbons

Furthermore, the combustion of hydrocarbons is the very method which upon choosing suitable reaction parameters can yield an increased portion of C70 in the fullerene soot At best, it may constitute up to 80% of the fullerene obtained. The gas pressure seems to be most influential for the CyofCuo ratio the fraction of C70 becomes larger with increasing pressure. The concentration of oxygen and the temperature of combustion are further important parameters. 

By now the method is also used to prepare large amounts of Qo- A plant producing about 5001 of fuUerene per year by benzene combustion has recently gone operative in Japan. 

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Carbon blacks with similar purity can be produced by partial combustion of hydrocarbon feedstock with high purity. A partial combustion of the hydrocarbon feedstock by co-injecting an oxidant like air in the reaction compartment provides the energy required for the thermal decomposition... 

In the absence of sufficient oxygen, partial combustion of hydrocarbons occurs. The products may be carbon monoxide (a very poisonous gas) or carbon (which deposits on spark plugs, in the cylinder head, and on the pistons of automobile engines). Many modern automobile engines now use microcomputer chips and sensors to control the air supply and to optimize the fuel/02 ratio. The reactions of methane with insufficient oxygen are... 

The heater outlet temperature declines as air flow is diminished past the absolute combustion point. That is, products of the partial combustion of hydrocarbons (aldehydes, ketones, CO, etc.) are formed, and the heating value of the fuel gas is effectively reduced. 

The standard Gibbs energy of combustion of glucose is -2880 kJ mol , so terminating its oxidation at pyruvate is a poor use of resources, akin to the partial combustion of hydrocarbon fuels in a badly tuned engine. In the presence of O2, pyruvate is oxidized further during the citric acid cycle and oxidative phosphorylation, which occur in the mitochondria of cells. 

In the production of synthesis gas for subsequent conversion to ammonia or methanol, for example, it is usually necessary to remove carbon dioxide formed either by partial combustion of hydrocarbons or by the water gas shift reactions. 

Flame or Partial Combustion Processes. In the combustion or flame processes, the necessary energy is imparted to the feedstock by the partial combustion of the hydrocarbon feed (one-stage process), or by the combustion of residual gas, or any other suitable fuel, and subsequent injection of the cracking stock into the hot combustion gases (two-stage process). A detailed discussion of the kinetics for the pyrolysis of methane for the production of acetylene by partial oxidation, and some conclusions as to reaction mechanism have been given (12). 

The oil-fiimace process, based on the partial combustion of Hquid aromatic residual hydrocarbons, was first introduced in the United States at the end of World War II. It rapidly displaced the then dominant channel (impingement) and gas-furnace processes because it gave improved yields and better product quahties. It was also independent of the geographical source of raw materials, a limitation on the channel process and other processes dependent on natural gas, making possible the worldwide location of manufacturing closer to the tire customers. Environmentally it favored elimination of particulate air pollution and was more versatile than all other competing processes. 

Soot. Emitted smoke from clean (ash-free) fuels consists of unoxidized and aggregated particles of soot, sometimes referred to as carbon though it is actually a hydrocarbon. Typically, the particles are of submicrometer size and are initially formed by pyrolysis or partial oxidation of hydrocarbons in very rich but hot regions of hydrocarbon flames conditions that cause smoke will usually also tend to produce unbumed hydrocarbons with thek potential contribution to smog formation. Both maybe objectionable, though for different reasons, at concentrations equivalent to only 0.01—0.1% of the initial fuel. Although thek effect on combustion efficiency would be negligible at these levels, it is nevertheless important to reduce such emissions. 

The recycling of PVC by hydrothermal techniques is described, in which PVC is thermally converted in a steam atmosphere into hydrogen chloride, hydrogen, carbon dioxide, carbon monoxide and some gaseous and liquid hydrocarbons. Whilst gasification with only steam is an endothermic reaction, partial combustion of PVC by the addition of small amounts of air, enables autothermic operation of the process to take place. This work deals... 

PCC [Partial combustion cracking] Not to be confused with precipitated calcium carbonate. A process for cracking crude petroleum or heavy oil to a mixture of olefins and aromatic hydrocarbons. The heat carrier is steam, produced by the partial combustion of the feed. Developed by Dow Chemical Company. It was piloted in 1979 and a larger plant was built in Freeport, TX, in 1984. 

In the temperature regime below 600°C, a more linear response is obtained. This is demonstrated in the response to hydrogen at 300°C compared with that at T> 600°C in Figure 2.5(b). In the lower temperature regime it is postulated that only partial combustion of the gas molecules occurs on the metal surface. This also means that at these lower temperatures, the various hydrocarbons are dissociated to different degrees and give substantially different responses at critical temperatures. 

The composition of the synthesis gas, particularly the concentrations of hydrogen, carbon monoxide, and carbon dioxide, affects the atmosphere throughout the reactor directly, and also indirectly by its effect on the composition of the recycle gas. Synthesis gas, prepared by partial combustion of methane or some less hydrogen-rich carbonaceous material, lacks sufficient hydrogen for the conversion of all the carbon monoxide to hydrocarbons, and in this sense the synthesis gas is deficient in hydrogen. Stoichiometrically methane has sufficient hydrogen to convert all its carbon to olefins by the two-step process ... 

E. Ranzi, M. Dente, A. Goldaniga, G. Bozzano, and T. Faravelli. Lumping Procedures in Detailed Kinetic Modeling of Gasification, Pyrolysis, Partial Oxidation, and Combustion of Hydrocarbon Mixtures. Prog. Combust. Sci. Techn., 27 99-139, 2001. 

Carbon black [1333-86-4 and soot are formed either by pyrolysis or by partial combustion of vapors containing carbon. Soot as an unwanted byproduct of combustion (e.g., in chimneys or diesel engines) is a poorly defined material. Besides carbon black particles, it often contains significant amounts of ash and high amounts of polycyclic aromatic hydrocarbons (PAH) [4.1]. Residual hydrocarbons, which can be determined by extraction with solvents (e.g., toluene), can account for 30 wt%. 

Partial oxidation processes rank next to steam-hydrocarbon processes in the amount of hydrogen made. They can use natural gas, refinery gas, or other hydrocarbon gas mixtures as feedstocks, but their chief advantage is that they can also accept liquid hydrocarbon feedstocks such as gas oil, diesel oil, and even heavy fuel oil. All processes employ noncatalytic partial combustion of the hydrocarbon feed with oxygen in the presence of steam in a combustion chamber at flame temperatures between 1300 and 1500°C. For example, with methane as the principal component of the feedstock ... 

The carbon black is produced by two ways the partial combustion of different hydrocarbons and the exothermic reaction of acetylene decomposition. About 10 million of tons are produced annually in the world, from which 99% for the tire industry. 

Synthesis gas manufacture by partial oxidation or autothermal cracking of crude oil fractions was developed by BASF/Lurgi, Texaco and Hydrocarbon Research. Heat for the thermal cracking is supplied by partial combustion of the feed in the presence of water. Recycled CO2 may also be added to the combustion to attain a desired CO/H2 ratio46. 

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