Nylon phenol hydrogenation

Caprolactam [105-60-2] (2-oxohexamethyleiiiiriiQe, liexaliydro-2J -a2epin-2-one) is one of the most widely used chemical intermediates. However, almost all of the aimual production of 3.0 x 10 t is consumed as the monomer for nylon-6 fibers and plastics (see Fibers survey Polyamides, plastics). Cyclohexanone, which is the most common organic precursor of caprolactam, is made from benzene by either phenol hydrogenation or cyclohexane oxidation (see Cyclohexanoland cyclohexanone). Reaction with ammonia-derived hydroxjlamine forms cyclohexanone oxime, which undergoes molecular rearrangement to the seven-membered ring S-caprolactam. 

C, b.p. 16UC. Manufactured by heating phenol with hydrogen under pressure in the presence of suitable catalysts. Oxidized to adipic acid (main use as intermediate for nylon production) dehydrogenated to cyclohexanone. 

AH commercial processes for the manufacture of caprolactam ate based on either toluene or benzene, each of which occurs in refinery BTX-extract streams (see BTX processing). Alkylation of benzene with propylene yields cumene (qv), which is a source of phenol and acetone ca 10% of U.S. phenol is converted to caprolactam. Purified benzene can be hydrogenated over platinum catalyst to cyclohexane nearly aH of the latter is used in the manufacture of nylon-6 and nylon-6,6 chemical intermediates. A block diagram of the five main process routes to caprolactam from basic taw materials, eg, hydrogen (which is usuaHy prepared from natural gas) and sulfur, is given in Eigute 2. 

Phenol, C6H5OH, is a benzene ring with a hydroxyl group, -OH, in place of a hydrogen. That makes it a member of the alcohol family. Most phenol is made by the oxidation route. At room temperature phenol is a solid but is corrosive like an acid. It is used to make phenolic resins and to make Bisphenol A (feed for epoxy and polycarbonate resins) and caprolactam (feed for Nylon 6). 

The important derivatives of benzene are shown in Table 8.8. Ethylbenzene is made from ethylene and benzene and then dehydrogenated to styrene, which is polymerized for various plastics applications. Cumene is manufactured from propylene and benzene and then made into phenol and acetone. Cyclohexane, a starting material for some nylon, is made by hydrogenation of benzene. Nitration of benzene followed by reduction gives... 

Pyrrolidone is a lactone used for the production of nylon-4. This reactant may be produced by the reduction ammoniation of maleic anhydride. s-Caprolactam, used in the production of nylon-6, may be produced by the Beckman rearrangement of cyclohexanone oxime (structure 17.11). The oxime may be produced by the catalytic hydrogenation of nitrobenzene, the photolytic nitrosylation of cyclohexane (structure 17.9), or the reaction of cyclohexanone and hydroxylamine (structure 17.10). Nearly one-half of the production of caprolactam is derived from phenol. 

Several oxidative routes are available to change cyclohexane to cyclohexanone, cyclohexanol, and ultimately to adipic acid or caprolactam. If phenol is hydrogenated, cyclohexanone can be obtained directly this will react with hydroxylamine to give cyclohexanone oxime that converts to caprolactam on acid rearrangement. Cyclohexane can also be converted to adipic acid, then adiponitrile, which can be converted to hexamethylenedi-amine. Adipic acid and hexamethylenediamine are used to form nylon 6,6. This route to hexamethylenediamine is competitive with alternative routes through butene. 

Furthermore, crystalline polymers do obey the rules even at room temperature in so far as swelling behaviour is concerned. This again is a demonstration that crystalline regions serve as physical cross-links. Some crystalline polymers with strong hydrogen bonding groups can be made to dissolve at room temperature. But in these cases a very specific interaction between polymer and solvent must occur. For example, cellulose is soluble in 70% sulphuric acid and in aqueous ammonium thiocyanate nylon 6.6 is soluble in phenol and in a 15% calcium chloride solution in methanol. 

Process Economics Program Report SRI International. Menlo Park, CA, Isocyanates IE, Propylene Oxide 2E, Vinyl Chloride 5D, Terephthalic Acid and Dimethyl Terephthalate 9E, Phenol 22C, Xylene Separation 25C, BTX, Aromatics 30A, o-Xylene 34 A, m-Xylene 25 A, p-Xylene 93-3-4, Ethylbenzene/Styrene 33C, Phthalic Anhydride 34B, Glycerine and Intermediates 58, Aniline and Derivatives 76C, Bisphenol A and Phosgene 81, C1 Chlorinated Hydrocarbons 126, Chlorinated Solvent 48, Chlorofluorocarbon Alternatives 201, Reforming for BTX 129, Aromatics Processes 182 A, Propylene Oxide Derivatives 198, Acetaldehyde 24 A2, 91-1-3, Acetic Acid 37 B, Acetylene 16A, Adipic Acid 3 B, Ammonia 44 A, Caprolactam 7 C, Carbon Disulfide 171 A, Cumene 92-3-4, 22 B, 219, MDA 1 D, Ethanol 53 A, 85-2-4, Ethylene Dichloride/Vinyl Chloride 5 C, Formaldehyde 23 A, Hexamethylenediamine (HMDA) 31 B, Hydrogen Cyanide 76-3-4, Maleic Anhydride 46 C, Methane (Natural Gas) 191, Synthesis Gas 146, 148, 191 A, Methanol 148, 43 B, 93-2-2, Methyl Methacrylate 11 D, Nylon 6-41 B, Nylon 6,6-54 B, Ethylene/Propylene 29 A, Urea 56 A, Vinyl Acetate 15 A. 

Substrates used included fiber-reinforced epoxy base polymer [FRP], nylon 66, polytetrafluoroethylene [Teflon], poly(ethylene terephthalate) [PET], phenolic resin, and thermoplastic polyimide [ULTEM, GE]. FRPs were the primary substrates used. Initially, they were cleaned with detergent in an ultrasonic bath followed by rinsing with deionized water and alcohol. For further cleaning, they were treated with oxygen plasma (1.33 seem, 60 W, 5 min) followed by a hydrogen plasma treatment (3 seem, 60 W, 5 min). 

Separation of benzene/cyclohexane mixture is investigated most extensively. This is not surprising because separation of this mixture is very important in practical terms. Benzene is used to produce a broad range of valuable chemical products styrene (polystyrene plastics and synthetic rubber), phenol (phenolic resins), cyclohexane (nylon), aniline, maleic anhydride (polyester resins), alkylbenzenes and chlorobenzenes, drugs, dyes, plastics, and as a solvent. Cyclohexane is used as a solvent in the plastics industry and in the conversion of the intermediate cyclohexanone, a feedstock for nylon precursors such as adipic acid. E-caprolactam, and hexamethylenediamine. Cyclohexane is produced mainly by catalytic hydrogenation of benzene. The unreacted benzene is present in the reactor s effluent stream and must be removed for pure cyclohexane recovery. 

Adipic acid is used in the manufacture of nylon 6,6. It is made by hydrogenation of phenol to a mixture of cyclohexanol and cyclohexanone (known as KA oil-ketone... 

The significance of the reaction of phenol with hydrogen has a number of important facets. First, the selective hydrogenation of phenol yields cyclohexanone, which is a key raw material in the production of both caprolactam for nylon 6 and adipic acid for nylon 6 . Second, due to the fact that phenol is an environmental toxin and phenolic waste has a variety of origins from industrial sources including oil refineries, petrochemical units, polymeric resin manufacturing and plastic units , catalytic hydrogenation of phenol is nowadays the best practicable environmental option . ... 

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