Butane material factor

The equivalent charge weight of TNT is calculated on the basis of the entire cloud content. FMRC recommends that a material-dependent yield factor be applied. Three types of material are distinguished Class I (relatively nonreactive materials such as propane, butane, and ordinary flammable liquids) Class II (moderately reactive materials such as ethylene, diethyl ether, and acrolein) and Class III (highly reactive materials such as acetylene). These classes were developed based on the work of Lewis (1980). Energy-based TNT equivalencies assigned to these classes are as follows ... 

Vapor Cloud Explosions. Lenoir and Davenport (Ref. 16) have summarized some major VCEs worldwide from 1921 to 1991. The materials involved in these incidents suggest that certain hydrocarbons—such as ethane, ethylene, propane, and butane—demonstrate greater potential for VCEs. Several factors may contribute to these statistics. These materials are prevalent in industry and are often handled in large quantities, increasing the potential for an incident. Certain inherent properties of the materials also contribute to their potential for explosion. These include flammability, reactivity, vapor pressure, and vapor density (with respect to air). 

The unavailability of suitable starting materials has hindered work in this area, but the reaction of cyclopentadienylindium(I) in Et20/benzene mixtures with 4,4,4-trifiuoro-l-(thien-2 -yl)butane-l,3-dionate (ttaH) gave the extremely hygroscopic In(tta), and similar derivatives of other bidentate ligands were obtained by this same process.14 The reactions of the analogous In(oxine) (oxine = 8-hydroxyquinoline anion) show that such InL species are easily oxidized to indium(III) complexes (see Section 25.2.4.8). The insolubility of the product in the reaction mixture is presumably an important factor in this method. 

Molecular probe analyses of the Type lib materials showed that they adsorbed significant quantities of CO2 and n-butane, but nearly zero amounts of the two larger probe molecules (see Table 3, Figures 7a and b). Because of this selective adsorption, these materials behaved similarly to the 5A size molecular sieves, but without the sharp cutoffs displayed by zeolites. However, it is remarkable that these Type lib materials adsorbed more of n-butane than the Type Ila materials. It may be that the addition of the fine oxidic particles led to interstices, which did not form in the preparation starting with the metal alkoxides. These interstices may provide adsorption sites for the larger molecules. Further investigations will be conducted to determine the structural factors that give rise to these different adsorptive properties. 

Figure 30 compares the long-range diffusivity of n-butane in a loose bed of NaX zeolite crystallites with that of the same sample after compaction under a pressure of 2.5 MPa. It is found that long-range diffusion in the compacted material is reduced by a factor on the order of 3, which may be attributed to a reduction of both (diminution of the intercrystalline void volume) and (decrease of the intercrystalline pore diameters and hence of the effective mean free path). This experimental result confirms that the contribution of intra-... 

On the other hand, yields to MA similar to those from -butane can be reached from processes using butenes, but the number of by-products obtained is also higher than from the -butane process. Indeed, the formation of small amounts of furan, acetaldehyde, crotonaldehyde, or methyl-vinyl-ketone are observed from n-butene, which makes the process more expensive due to the need for a purification step. During the selective oxidation of -butane (a cheaper raw material) these products are not formed, but the main by-products are CO and CO2. Indeed, both parallel and consecutive reactions of total combustion must be taken into account in the process from n-butane since they are mainly responsible for the limited yield to MA. In this way, -butane conversion lower than 75-80% has been reported to be adequate in order to avoid further oxidation of MA, an important factor in the decrease of the process selectivity. 

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