Hydrocarbon fractions

Zeohte 5A is used because its pores can size-selectively adsorb straight-chain molecules while excluding branched and cycHc species. The normal hydrocarbon fraction has better than 95% purity, and the higher octane isomer fraction contains less than 2% normal hydrocarbons (64). 

Olefins are produced primarily by thermal cracking of a hydrocarbon feedstock which takes place at low residence time in the presence of steam in the tubes of a furnace. In the United States, natural gas Hquids derived from natural gas processing, primarily ethane [74-84-0] and propane [74-98-6] have been the dominant feedstock for olefins plants, accounting for about 50 to 70% of ethylene production. Most of the remainder has been based on cracking naphtha or gas oil hydrocarbon streams which are derived from cmde oil. Naphtha is a hydrocarbon fraction boiling between 40 and 170°C, whereas the gas oil fraction bods between about 310 and 490°C. These feedstocks, which have been used primarily by producers with refinery affiliations, account for most of the remainder of olefins production. In addition a substantial amount of propylene and a small amount of ethylene ate recovered from waste gases produced in petroleum refineries. 

The polymerization of monomers to form hydrocarbon resins is typically carried out by either the direct addition of catalyst to a hydrocarbon fraction or by the addition of feed to a solvent—catalyst slurry or solution. Most commercial manufacturers use a continuous polymerization process as opposed to a batch process. Reactor temperatures are typically in the range of 0—120°C. 

Of the many solvents proposed, only a few have found commercial appHcation, including water (Hbls), anhydrous ammonia (SBA), chilled methanol (Montecatini), /V-methy1pyrro1idinone (BASF), butyrolactone, acetone, dimethyl-form amide, and hydrocarbon fractions. 

The price of Gedarwood oil from Texas in 1995 was 7.70/kg and the price of the oil from Virginia was 15.18/kg (69). Distillation of the oil gives two main fractions, the cedrene or hydrocarbon fraction, and the alcohol fraction consisting of impure cedrol, which when purified by crystallization can be used direcdy in perfumery. Gedrenol is a product comprising a mixture of cedrol and its isomers widdrol and some ketone components. 

Acetyl cedrene (95) is obtained by the acetylation of the hydrocarbon fraction, a-cedrene [469-61-4] (91). The product has a woody, warm-ambergris, and musk odor, and many types of products are available (189). 

Of the four commercial processes for the purification of carbon monoxide two processes are based on the absorption of carbon monoxide by salt solutions, the third uses either low temperature condensation or fractionation, and the fourth method utilizes the adsorption of carbon monoxide on a soHd adsorbent material. AH four processes use similar techniques to remove minor impurities. Particulates are removed in cyclones or by scmbbing. Scmbbing also removes any tars or heavy hydrocarbon fractions. Acid gases are removed by absorption in monoethanolamine, hot potassium carbonate, or by other patented removal processes. The purified gas stream is then sent to a carbon monoxide recovery section for final purification and by-product recovery. 

There are several important Hquid fuels, ranging from volatile fuels for internal combustion engines to heavy hydrocarbon fractions, sold commercially as fuel oils. The technology for the combustion of Hquid fuels for spark-ignition and compression-ignition internal combustion engines is not described here. 

Effects. Trays can become damaged several ways. A pressure surge can cause damage. A slug of water entering a heavy hydrocarbon fractionator will produce copious amounts of vapor. The author is aware of one example where all the trays were blown out of a crude distillation column. If the bottom liquid level is allowed to reach the reboiler outlet line, the wave action can damage some bottom trays. 

Basically, a gas absorption tower is a unit in which the desirable light ends components are recovered from the gas feed by dissolving them in a liquid passing through the tower countercurrently to the gas. The liquid absorbent is called lean, oil, and it usually consists of a hydrocarbon fraction in the gasoline boiling range. After the absorption step, the liquid which now contains the desired constituents in solution is referred to as fat oil. A similarly descriptive nomenclature is applied to the gas, which is referred to as wet gas when it enters the tower and as dry gas when it leaves the absorber. 

Concentration of the dissolved hydrocarbon fraction in groundwater near the dwelling... 

For low purity hydrocarbon fraction, the number of drip or separate flow points shoitid be 6-10 drip points/ft of tower cross-section surface area. 

A saturated hydrocarbon fraction, bp 60-71°, available from the Skelly Oil Company, Kansas City, Missouri... 

Sampling Procedure. The sample extraction technique previously described was used in this work (8). However, a heated palladium thimble was also used to separate hydrogen and hydrocarbon fractions of the samples. No exchange occurred during the separation process in agreement with observations of other workers (30). In experiments using NH3 as a minor additive, the ammonia fraction was separated by means of appropriate cold traps. 

The performance of a novel microwave-induced pyrolysis process was evaluated by studying the degradation of HDPE and aluminiutn/polymer laminates in a semibatch bench-scale apparatus. The relationship between temperature, residence time of the pyrolytic products in the reactor, and the chemical composition of the hydrocarbon fraction produced was investigated. 28 refs. 

As further subfractionation facilitates subsequent studies at a molecular level, further separation into compound groups is applied. For example, the saturated hydrocarbon fraction can be treated with 5 A molecular sieves or urea for the removal of n-alkanes, leaving behind a fraction of branched and cyclic alkanes [7,8]. The procedure is described in the following text in detail. 

Aliphatic hydrocarbon fractions are sometimes fractionated further into the fractions of normal and branched/cyclic alkanes by urea clathration or molecular sieves... 

The TLC plates prepared in a similar maimer may be used to separate monoar-omatie hydrocarbon fractions with Rj values in the range 0.29 to 0.78 from polyaromatic hydrocarbon fractions (Rj = 0.06 to 0.29) [84]. 

To obtain alkanes and alkenes from ahphatic hydrocarbon fractions, argentation PLC was proposed that utihzed sihca-gel-60-precoated plates impregnated with 5% or 10% of AgNOj [37,80,99,100]. In some applications, TLC plates impregnated... 

Bonaga, G. and Giumanini, A. G. (1986). Chemical composition of chestnut honey Analysis of the hydrocarbon fraction. J. Apicult. Res. 25,113-120. 

Drickamer, H. G. and J. B. Bradford, Overall Plate Efficiency of Commercial Hydrocarbon Fractionating Columns, Trans. AIChE 39, 319,1943. 

Because gasoline is composed of some highly volatile and soluble hydrocarbon fractions, its components can move in the subsurface in three states vapor, solute, and liquid. The form of its components in the soil are vapor, solute, free product, and adsorbate. The multiphase flow of... 

Compositional analysis shows a decrease in the percentage of polar compounds in the oils with increasing residence time (see Table II). The decrease in polar content is substantiated by a lower sulphur content and results in a lower viscosity (see Table II). The oil becomes more aromatic, as shown by n.m.r. spectroscopy (see Table II), with increasing time at temperature, while the molecular weights showed little change. G.l.c. analysis of the saturate hydrocarbon fractions from elution chromatography indicated little change in the saturates with residence time. 

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