Butanes-plus

LPG is a mixture of propane and n- and iso-butanes, plus small amounts of theu olefmie eounterparts. The main sourees are natural gas wells, gas from erude oil wells and the eraeking of etude oil. The requirements for eommereial LPG are defined in national standards and a stenehing agent is added for some uses. 

An example for the reaction of methane with ethylene to give butane plus hydrogen is written as... 

Pyro-gas fraction -10-30% (contains 1 % sulfur) CO2, carbon monoxide, methane, ethane, butadiene, propane, propene and butane, plus hydrocarbons ( dependent on the amount of oxygen that is available). 

The bond matrix expresses 2 C—C bonds plus 8 C—H bonds for propane and 3 C—C bonds plus 10 C—H bonds for n-butane. Eaeh enthalpy of atomization is obtained by subtraeting the enthalpy of formation of the alkane from the sum of atomie atomization enthalpies (C 716 H 218 kJ mol ) for that moleeule. For example, the moleeular atomization enthalpy of propane is 3(716) +8(218) — (—104) = 3996 kJ mol . Enthalpies of formation are available from Pedley et al. (1986) or on-line at www.webbook.nist.gov. 

Polymerization of AA and BB monomers is illustrated by butane-1,4-diol and adipic acid. The aabb repeat unit in the polymer has an Mq value of 200. If Eq. (5.4) is used to evaluate it gives the number of aa plus bb units therefore = 200(hj )/2. 

Total Hydrocarbon Gontent. The THC includes the methane combined in air, plus traces of other light hydrocarbons that are present in the atmosphere and escape removal during the production process. In the typical oxygen sample, methane usually constitutes more than 90% of total hydrocarbons. The rest may be ethane, ethylene, acetylene, propane, propylene, and butanes. Any oil aerosol produced in lubricated piston compressor plants is also included here. 

The de-butanizer works in a similar manner. The upstream tower (depropanizer) determines the maximum vapor pressure of the butane product. If the concentration of propane-minus is too large in the inlet stream, the vapor pressure of the butane overheads will be too high. Similarly, the concentration of pentanes-plus in the butane will depend upon the... 

With propene, n-butene, and n-pentene, the alkanes formed are propane, n-butane, and n-pentane (plus isopentane), respectively. The production of considerable amounts of light -alkanes is a disadvantage of this reaction route. Furthermore, the yield of the desired alkylate is reduced relative to isobutane and alkene consumption (8). For example, propene alkylation with HF can give more than 15 vol% yield of propane (21). Aluminum chloride-ether complexes also catalyze self-alkylation. However, when acidity is moderated with metal chlorides, the self-alkylation activity is drastically reduced. Intuitively, the formation of isobutylene via proton transfer from an isobutyl cation should be more pronounced at a weaker acidity, but the opposite has been found (92). Other properties besides acidity may contribute to the self-alkylation activity. Earlier publications concerned with zeolites claimed this mechanism to be a source of hydrogen for saturating cracking products or dimerization products (69,93). However, as shown in reaction (10), only the feed alkene will be saturated, and dehydrogenation does not take place. 

Condensate is normally considered the entrapped liquids in process or production gas streams due to temperature or pressure, in the typically in the range of C3, C4, C5 or heavier hydrocarbon liquids. It is also known as natural gasoline C5 plus and pentanes plus, and as a liquid at normal temperatures and pressures it generally consists of a mixture of the C5 (pentanes) and heavier hydrocarbons. It is normally condensed (i.e., by expansion and cooling of the gas) out of the process stream in primary separation processes, where it is then sent to other refinery processes to further separate the condensate into its primary fractions, i.e., propane, butane, and liquids constituents. 

The neurotoxicity of pure M-hexane (99%) has been compared to mixed hexanes (a mixture containing the -hexane isomers 2-methylpentane, 3-methylpentane, cyclohexane, methyl cyclopentane, and 2,3-dimethyl butane with approximately 1% -hexane) (IRDC 1981). The mixture was intended to be more representative of products used commercially. In this experiment, groups of Sprague-Dawley rats were exposed to -hexane alone (500 ppm), mixed hexanes (494 ppm) or -hexane plus mixed hexanes (992 ppm) daily for 6 months, 22 hours a day. No deaths occurred as a result of treatment. 

The source of these compounds is varied. The butanes are found naturally in crude oils and natural gas. They, plus the olefins, are products of various refinery processes and of olefins plants. They are separated by fractionation, except for butadiene and isobutylene, which are sometimes recovered by extractive distillation. They all vaporize at room temperature, so they are handled in closed, pressurized systems.. 

An alternative approach for the utilization of biomass resources for energy applications is the production of dean-buming liquid fuels. In this respect, current technologies to produce liquid fuels from biomass are typically multi-step and energy-intensive processes. Aqueous phase reforming of sorbitol can be tailored to produce selectively a clean stream of heavier alkanes consisting primarily of butane, pentane and hexane. The conversion of sorbitol to alkanes plus CO2 and water is an exothermic process that retains approximately 95% of the heating value and only 30% of the mass of the biomass-derived reactant [278]. 

In general, things are simpler than that, much to our advantage. Within the limits set by the precision of the present estimates, structural features like the chair, boat, or twist-boat conformations of cyclohexane rings, as well as the butane-gawc/ze effects or the cis-tmns isomerism of ethylenic compounds leave no recognizable distinctive trace in zero-point plus heat content energies. Indeed, whatever residual, presently... 

Cyclization remains the preferred mode of reaction when the irradiation is carried out in a solvent containing abstractable hydrogen atoms. Irradiation of 4,5-octanedione in butanal gave 92% of cyclized product plus smaller amounts of abstraction products. Since the products account for more than 100% of the diketone consumed, it must be assumed that some of the... 

Cyclopropane derivatives, including spiropentanc, have proven to be virtually inert towards carbenes,1 For this reason, no literature report that describes cyclobutane synthesis from a C3 and a Cj building block by ring enlargement of cyclopropanes exists. However, due to the partial p character, as well as the increasing reactivity caused by its strain, the central bond of bicyclo[1.1.0]butane (l)2 has been found to react with carbenes.1 Photolysis of diazomethane in the presence of bicyclo[1.1.0]butane (1) at — 50 C provides a mixture of several compounds. The major fraction of the material (80%) was analyzed by means of NMR spectrometry and found to consist of penta-1,4-diene (2, 21%) and bicyclo[l.l.l]pentane (3, 1%), plus several other known compounds as well as some unidentified products.3 The mechanistic pathway for the formation of bicyclo[l.l.l]pentane (3) has not been addressed in detail, but it is believed that a diradical intermediate is involved, as shown below.3... 

Natural gasoline 20% butanes, 80% pentanes-plus. Finished gasoline, etc. 5% butanes, 95% pentanes-plus. Raw condensate (plant) 80% gasoline, 20% heavier. 

Roughly speaking, this use includes ail of the pentanes and heavier hydrocarbons distilling up to gasoline end point plus some of the butanes, totaling about 70% of the recent annual production of natural gas liquids. 

Use properties of n-butane and n-pentane for butanes and pentanes and of octane for hexane plus. 

It has been suggested previously that the thermal cycloreversion of cyclohexene to ethylene plus buta-1,3-diene proceeds via a vinylcyclobutane intermediate and that, as a consequence, the stereochemistry of deuterium labels on the cyclohexene is not reflected in the deuterated ethenes obtained. This conclusion is supported by results of a study of the stereochemistry of thermal conversion of 1 -viny 1-2.3-r/.v-didcuteriocyclo-butane to butadiene and 1,2-dideuterioethylenes equal amounts of ( )-CHD=CHD and (Z)-CHD=CHD were formed.32... 

The field is defined here around the activation of butane, propane and ethane plus the oxidation of propene. The reason for this boundary is the similarity of the chemistry and the great need to understand the mechanism of selectivity of activated oxygen in these multi-step reactions. The processes cannot be conducted at high temperatures such as with methane activation as the target products are not stable under conditions where alkane activation is fast. The selective oxidation of... 

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