Hydrogen/hydrocarbon mixtures

Titanium carbide may also be made by the reaction at high temperature of titanium with carbon titanium tetrachloride with organic compounds such as methane, chloroform, or poly(vinyl chloride) titanium disulfide [12039-13-3] with carbon organotitanates with carbon precursor polymers (31) and titanium tetrachloride with hydrogen and carbon monoxide. Much of this work is directed toward the production of ultrafine (<1 jim) powders. The reaction of titanium tetrachloride with a hydrocarbon-hydrogen mixture at ca 1000°C is used for the chemical vapor deposition (CVD) of thin carbide films used in wear-resistant coatings. 

It has been demonstrated that highly selective and active catalysts can be formed by activating either oxidized molybdenum carbide Mo2C or molybdenum oxide Mo03 itself with a hydrocarbon/hydrogen mixture. The active catalysts obtained from the two sources are similar in their catalytic behaviour and are probably both molybdenum oxycarbide (MoO Cy). They are selective for the isomerization of a number of n-hydrocarbons with the main products always consisting of monomethyl isomers but with an important contribution from the dibranched products,... 

Prospects for inexpensive and large-scale production of diamond increased tremendously in the mid 1970s when researchers discovered that diamond can be grown as thin coatings at low deposition pressures (10 -10 Pa) from hydrocarbon/hydrogen mixtures by chemical vapor deposition (CVD). Since then, there has been an explosion in diamond and related- material research with the expectation that CVD will allow faster, cheaper, and easier production of diamond. CVD diamond technology was proved to be more versatile in coating intricate shapes and could be less expensive than HPHT. " ... 

Gas permeabUities of isotropic PDMS films were determined over a temperature range of 35°C to 20°C for pure gases and a series of binary n-butane/methane and multicomponent hydrocarbons/hydrogen mixtures [38]. Pure-gas permeabUities in PDMS as a function of reciprocal temperature are presented in Figure 9.15. It can be seen that the decrease in temperature... 

A batch process developed by Tibbetts [46] passed a hydrocarbon/hydrogen mixture over a substrate held at about 1000°C on which iron-containing particles, acting as a catalyst, had been deposited. Figure 2.33 shows in a simple way how filaments are formed by a catalytic particle and growth mechanisms are detailed by Dresselhaus et al [47] Properties of VGCF are given in Table 2.9. 

These tubes were contained within a mullite muffle, passing a hydrocarbon/hydrogen mixture over the mullite substrate, maintained at about 1000°C, on which iron-containing particles, acting as a catalyst, had been deposited. It was found beneficial to obtain a build-up in the equipment of reactive hydrocarbons (C2H c)> formed in the process, to promote a faster rate of formation, since methane itself tends to be un-reactive and has poor solubility in the iron particles. The filaments could be made several centimeters in length, with diameters of 7-10 pm and when removed from the substrate, had a variety of forms. At temperatures... 

A 6-in. carbon steel elbow in a Los Angeles refinery ruptured releasing a hydrocarbon/ hydrogen mixture on October 8, 1992. The vapor cloud ignited within seconds. The explosion damaged nearby buildings and shattered windows several miles away and was recorded as a sonic boom at the California Institute of Technology about 20 miles away [29]. 

The carbon may either be dissolved, form carbides or be deposited. Carbon deposition as graphite is possible at carbon activities ac > 1 - For hydrocarbon-hydrogen mixtures, the carbon activity can be calculated according to... 

An example of the extraordinary separation properties of PTMSP for hydrocarbon/hydrogen mixtures is given in Figures 8a and 8b, which present propane and hydrogen permeability coefficients and mixture separation factors as a fonction of propane relative pressure in the feed gas. As the propane relative pressure increases, propane permeability increases by less than a factor of two, from... 

The reason is that classical thermodynamics tells us nothing about the atomic or molecular state of a system. We use thermodynamic results to infer molecular properties, but the evidence is circumstantial. For example, we can infer why a (hydrocarbon + alkanol) mixture shows large positive deviations from ideal solution behavior, in terms of the breaking of hydrogen bonds during mixing, but our description cannot be backed up by thermodynamic equations that involve molecular parameters. 

It follows from the second law of thermodynamics that the optimal free energy of a hydrocarbon-water mixture is a function of both maximal enthalpy (from hydrogen bonding) and minimum entropy (maximum degrees of freedom). Thus, nonpolar molecules tend to form droplets with minimal exposed surface area, reducing the number of water molecules affected. For the same reason, in the aqueous environment of the hving cell the hydrophobic portions of biopolymers tend to be buried inside the structure of the molecule, or within a lipid bilayer, minimizing contact with water. 

Of the many possible non-hydrocarbon - water binary systems which are related to substitute gas processes, the data on only the water binaries containing H2S, C02, N2, and NH3 were used in this study. The treatment of hydrogen, a quantum gas, is different from that of the other gases. A separate paper will deal with the correlation of the data on hydrogen mixtures. 

The transition length for deflagration to detonation is of the order of a meter for highly reactive fuels such as acetylene, hydrogen, and ethylene, but larger for most other hydrocarbon-air mixtures. Consequently, most laboratory... 

Atmospheric and vacuum distillation units (Figures 4.3 and 4.4) are closed processes, and exposures are expected to be minimal. Both atmospheric distillation units and vacuum distillation units produce refinery fuel gas streams containing a mixture of light hydrocarbons, hydrogen sulfide, and ammonia. These streams are processed through gas treatment and sulfur recovery units to recover fuel gas and sulfur. Sulfur recovery creates emissions of ammonia, hydrogen sulfide, sulfur oxides, and nitrogen oxides. 

Iron has a rich surface coordination chemistry that forms the basis of its important catalytic properties. There are many catalytic applications in which metallic iron or its oxides play a vital part, and the best known are associated with the synthesis of ammonia from hydrogen and nitrogen at high pressure (Haber-Bosch Process), and in hydrocarbon synthesis from CO/C02/hydrogen mixtures (Fischer-Tropsch synthesis). The surface species present in the former includes hydrides and nitrides as well as NH, NH2, and coordinated NH3 itself. Many intermediates have been proposed for hydrogenation of carbon oxides during Fischer-Tropsch synthesis that include growing hydrocarbon chains. 

Chlorine-hydrogen mixture can explode in the presence of sunlight, heat or a spark. Also, it can explode when mixed with acetylene or diborane at ordinary temperatures, and with ethylene, fluorine, and many hydrocarbons in the presence of heat, spark or catalysts. 

F) K.K. Andreev, "Termicheskoye Razlo-zheniye i Goreniye Vzryvchatykh Veshchestv (Thermal Decomposition and Combustion of Explosive Substances), GosEnergoIzdat, Moscow(1957) G) P. Breisacher et al, "Flame Front Structure of Lean Diborane-Air and Diborane-Hydrocarbon-Air Mixtures", 7thSympCombstn(1959), PP 894-902 H) M. Getstein, "A Study of Alkylsilane Flames , Ibid, pp 903-05 I) P.L. Harrison, "The Combustion.of Titanium and Zirconium , Ibid, pp 913-20 J) J.D. Lewis A.C, Merrington, "Combustion of n-Heptane Spray in the Decomposition Products of Concentrated Hydrogen Peroxide , Ibid, pp 953-57... 

This second-order decomposition of hydrogen peroxide has been studied independently, and its rate parameters are known. The activation energy is ca. 48 keal., and its lifetime is about 1 second at about 900°K. At temperatures of ca. 450° to 550°C., it proceeds at a sufficiently rapid rate to be responsible for initiating the normal explosion limit, which one finds for stoichiometric hydrocarbon-oxygen mixtures. 

The phase behavior of hydrocarbon + water mixtures differs significantly from that of normal hydrocarbon mixtures. Differences arise from two effects, both of which have their basis in hydrogen bonding. First, the hydrate phase is a significant part of all hydrocarbon + water phase diagrams for hydrocarbons with a molecular size lower than 9 A. Second, water and hydrocarbon molecules are so different that, in the condensed state, two distinct liquid phases form, each with a very low solubility in the other. 

Stewart and Hack (5.) have presented operating characteristics of pressure swing adsorption systems for reducing impurities in a hydrogen stream from 40 vol percent to 1 ppm. Impurities included ammonia, water, methane, carbon monoxide, carbon dioxide, nitrogen, and several hydrocarbons. In this study heatless adsorption is used to separate hydrogen sulfide-hydrogen mixtures and the experimental results are compared with theoretical models. 

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