Propylene boiling point

ElexibiHty allows the operator to pick and choose the most attractive feedstock available at a given point in time. The steam-cracking process produces not only ethylene, but other products as weU, such as propylene, butadiene, butylenes (a mixture of monounsaturated C-4 hydrocarbons), aromatics, etc. With ethane feedstock, only minimal quantities of other products ate produced. As the feedstocks become heavier (ie, as measured by higher molecular weights and boiling points), increasing quantities of other products are produced. The values of these other coproduced products affect the economic attractiveness and hence the choice of feedstock. 

Isopropyl Ether. Isopropyl ether is manufactured by the dehydration of isopropyl alcohol with sulfuric acid. It is obtained in large quantities as a by-product in the manufacture of isopropyl alcohol from propylene by the sulfuric acid process, very similar to the production of ethyl ether from ethylene. Isopropyl ether is of moderate importance as an industrial solvent, since its boiling point Hes between that of ethyl ether and acetone. Isopropyl ether very readily forms hazardous peroxides and hydroperoxides, much more so than other ethers. However, this tendency can be controlled with commercial antioxidant additives. Therefore, it is also being promoted as another possible ether to be used in gasoline (33). 

Propane is separated from propylene by distillation. The compounds have close boiling points and the relative volatility will be low. For a feed composition of 10 per cent w/w propane, 90 per cent w/w propylene, estimate the number of theoretical plates needed to produce propylene overhead with a minimum purity of 99.5 mol per cent. The column will operate with a reflux ratio of 20. The feed will be at its boiling point. Take the relative volatility as constant at 1.1. 

As a general rule difficult or expensive separations should be performed last, since by that time less total material will be involved. Consider Table 4-1, which gives the product mix obtained in a cracking furnace of an ethylene plant and the normal boiling points of the compounds. Suppose it is desired to separate the six groups listed in the table using distillation. The separation of ethylene from ethane and propylene from propane will be the most difficult because they have the smallest boiling-point differences. Therefore, these steps should be performed last. 

About half the propane produced annually in the U.S. is used as a domestic and industrial fuel. When it is used as a fuel, propane is not separated from the related compounds, butane, ethane, and propylene. Butane, with boiling point -0.5 °C (31.1 °F), however, reduces somewhat the rate of evaporation of the liquid mixture. Propane forms a solid hydrate at low temperatures, and this causes great inconvenience when a blockage occurs in a natural-gas line. Propane is used also as so-called bottled gas, as a motor fuel, as a refrigerant, as a low-temperature solvent, and as a source of propylene and ethylene. 

Propylene oxide is a low boiling point, flammable liquid, readily soluble in both water and the more common organic solvents, such as alcohol, ether, and aliphatic and aromatic hydrocarbons. Commercial sales involve only technical grade (about 98%), and bulk movements require a hazardous material shipping label. Standard transport equipment (trucks, tank cars, and barges) can be used. 

Two compounds are included in tins category of antimicrobials. One is tile gas, ethylene oxide, the other, propylene oxide. a colorless liquid with a boiling point of 35 0 Ethylene is highly reactive and must be used carefully and only with proper equipment. Somewhat less hazardous from an explosion standpoint, propylene oxide also has an explosive range of 2-22%. Consequently, these materials are usually mixed with inert substances, such as carbon dioxide or organic diluents. 

Propylene from propane 191 Close-boiling-point problem... 

Propane and propylene have similar atmospheric boiling points (propane -42.1°C, propylene -47.70°C) and, as a result, the separation of these compounds requires highly complicated units. Distillation is by far the most commonly used separation process in the chemical industry today. The variants in use are ... 

Consider two very similar components, propylene [1] and propane [3], with close boiling points. The ideal relative volatility is now defined as... 

The reaction vessel was heated to 150°C and pressurized with propylene. The temperature then increased slowly. The start of the reaction was evidenced by a drop in the propylene pressure at 190°C and at a pressure of 21-35 atm. The product was hydrolyzed and fractionated to yield 105 parts of 2,6-diisopropylphenol. Boiling point 135.5-136.5°C. 

Excess benzene stops the reaction at the monoalkylated stage and prevents the polymerization of propylene. The cumene is separated by distillation, boiling point 153°C. Other catalysts that have been used are aluminum chloride and sulfuric acid. 

Isoprene (melting point -146°C, boiling point 34°C, density 0.6810) may be produced by the dehydrogenation of iso-pentane in the same plant used for the production of butadiene. However, the presence of 1,3-pentadiene (for which there is very little market) requires a purification step. One method produces isoprene from propylene. Thus, dimerization of propylene to 2-methyl-1-pentene is followed by isomerization of the 2-methyl-1-pentene to 2-methyl-2-pentene, which upon pyrolysis gives isoprene and methane. 

Nonene (n-nonene boiling point 146°C, density 0.730) was originally made by the trimerization of propylene (CH3CH=CH2) to give a branched nonene this product now has limited use for detergents because of nonbiodegradability. 

Propene (propylene, CH3CH=CH2, boiling point -47.7"C, flash point -107.8°C, ignition temperature 497.2°C) is a colorless, flammable gas with a slightly sweet aroma. 

Propylene glycol (boiling point 189°C, density 1.0361) is produced by hydration of propylene oxide in a process similar to that for the production of ethylene glycol by hydration of ethylene oxide. 

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