Hydrogen ratios

Mass spectrometry has been used to determine the amount of H2 in complex gas mixtures (247), including those resulting from hydrocarbon pyrolysis (68). Mass spectrometry can also be used to measure hydrogen as water from hydrocarbon combustion (224,248). Moreover, this technique is also excellent for determining the deuterium hydrogen ratio in a sample (249,250). 

Mesophase formation in coal-tar pitch is encouraged by a reduction of the natural quinoline-insoluble matter content, which resembles carbon black but is not optically anisotropic and is characterized by an atomic carbon hydrogen ratio of 4 1. In contrast, the atomic carbon hydrogen ratio of mesophase is about 2 1. 

Anthracite. Anthracite is preferred to other forms of coal (qv) in the manufacture of carbon products because of its high carbon-to-hydrogen ratio, its low volatile content, and its more ordered stmcture. It is commonly added to carbon mixes used for fabricating metallurgical carbon products to improve specific properties and reduce cost. Anthracite is used in mix compositions for producing carbon electrodes, stmctural brick, blocks for cathodes in aluminum manufacture, and in carbon blocks and brick used for blast furnace linings. 

Aromaticity is the most important property of a carbon black feedstock. It is generally measured by the Bureau of Mines Correlation Index (BMCI) and is an indication of the carbon-to-hydrogen ratio. The sulfur content is limited to reduce corrosion, loss of yield, and sulfur in the product. It may be limited in certain locations for environmental reasons. The boiling range must be low enough so that it will be completely volatilized under furnace time—temperature conditions. Alkane insolubles or asphaltenes must be kept below critical levels in order to maintain product quaUty. Excessive asphaltene content results in a loss of reinforcement and poor treadwear in tire appHcations. 

The carbon monoxide concentration of gas streams is a function of many parameters. In general, increased carbon monoxide concentration is found with an increase in the carbon-to-hydrogen ratio in the feed hydrocarbon a decrease in the steam-to-feed-carbon ratio increase in the synthesis gas exit temperature and avoidance of reequiUbration of the gas stream at a temperature lower than the synthesis temperature. Specific improvement in carbon monoxide production by steam reformers is made by recycling by-product carbon dioxide to the process feed inlet of the reformer (83,84). This increases the relative carbon-to-hydrogen ratio of the feed and raises the equiUbrium carbon monoxide concentration of the effluent. 

Carbon black is produced by the partial combustion or the thermal decomposition of natural gas or petroleum distillates and residues. Petroleum products rich in aromatics such as tars produced from catalytic and thermal cracking units are more suitable feedstocks due to their high carbon/hydrogen ratios. These feeds produce blacks with a... 

The carbon/hydrogen ratio of gas is considerably lower than oil or coal, which results in a flame of very low luminosity. Radiation from the flame is therefore low and furnace design must allow for heat transfer to be primarily by convection and conduction, together with re-radiation from hot surfaces. 

Resistance to burning depends on many factors. It is, however, to be noted that those polymers that only burn in air enriched with oxygen tend to have high carbon hydrogen ratios and/or may also emit materials during degradation, such as hydrogen chloride, that are inherent flame-retardants. 

Low smoke emission is also often associated with a high carbon hydrogen ratio. Table 18.15 gives some collected data for the limiting oxygen index. 

A side stream from the cathode product mixture is passed over a room temperature alumina bed to remove HF. The nitrogen/hydrogen ratio is estimated, and from this ratio and the known flow rate of the nitrogen reference stream, the current efficiency for hydrogen production is calculated. 

The deposition temperature range is 250-600°C and the pressure is up to 20 T orr. T o minimize carbon inclusion, the carbonyl is highly diluted with hydrogen (ratio of 1/100) and high purity deposits can be obtained. PI Reaction (6) has a low temperature reaction and isbeing considered for deposition on silicon and III-V semiconductors. 

Keeping in mind the entire set of components in the climate system as depicted in Figs 17-2,4-13, and 17-3, we can now re-examine Fig. 1-2 to emphasize that biogeochemical cycles are coupled with the climate system. The temperature (as inferred from the record of the deuterium to hydrogen ratio in Antarctic ice) covaries with CO2, CH4 and other species that derive from biological processes. Two simple, if extreme, possibilities can be drawn ... 

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