Chevron Oxidator

FIGURE 5.24 Chevron Oxidator BN results for hydrocracked and solvent refined stocks Oxidator times (hr) versus log (UV absorbance at 226 nm). 

Chevron Chemical Co. began commercial production of isophthahc acid in 1956. The sulfur-based oxidation of / -xylene in aqueous ammonia at about 320°C and 7,000—14,000 kPa produced the amide. This amide was then hydrolyzed with sulfuric acid to produce isophthahc acid at about 98% purity. Arco Chemical Co. began production in 1970 using air oxidation in acetic acid catalyzed by a cobalt salt and promoted by acetaldehyde at 100—150°C and 1400—2800 kPa (14—28 atm). The cmde isophthahc acid was dissolved and recrystallized to yield a product exceeding 99% purity. The Arco technology was not competitive and the plant was shut down in 1974. 

Close examination of these areas under a low-power microscope revealed smoothly rippled, spherical surfaces in the weld region and a chevron pattern that pointed back to the weld in the plate. Cross sections cut through the weld revealed substantial subsurface porosity and regions where oxidized surfaces prevented metallurgical bonding of the weld (Fig. 

Theories of the oxidation of tantalum in the presence of suboxide have been developed by Stringer. By means of single-crystal studies he has been able to show that a rate anisotropy stems from the orientation of the suboxide which is precipitated in the form of thin plates. Their influence on the oxidation rate is least when they lie parallel to the metal interface, since the stresses set up by their oxidation to the pentoxide are most easily accommodated. By contrast, when the plates are at 45° to the surface, complex stresses are established which create characteristic chevron markings and cracks in the oxide. The cracks in this case follow lines of pores generated by oxidation of the plates. This behaviour is also found with niobium, but surprisingly, these pores are not formed when Ta-Nb alloys are oxidised, and the rate anisotropy disappears. However, the rate remains linear it seems that this is another case in which molecular oxygen travels by sub-microscopic routes. 

K.D. Nelson and F. Plavac, Sulfurized polyisobutylene based wear and oxidation inhibitors, US Patent 7 414 013, assigned to Chevron Oronite Company LLC (San Ramon, CA), August 19, 2008. 

Application of an electric field normal to the plates (typically the plates are coated with thin films of conducting glass such as indium-tin oxide) unwinds the helix if there is one, and also may cause the polar axis to orient normal to the plates (along the field), or even flatten the chevrons. It should be stressed that any added orientation of molecular dipoles along the field direction should be a weak secondary effect — the polar order occurring in the FLC phase is a thermodynamic property of the phase and not dependent upon applied fields. 

Standard Oil of California added the petrochemicals of Gulf Oil, purchased in 1984, to its subsidiary Chevron Chemical. Other United States petrochemical producers took advantage of special circumstances. Amoco was served by a strong terephthalic (TPA) base and its good performance in polypropylene Arco, by its Lyondell subsidiary in Channelview, Texas, and by its development of the Oxirane process through which propylene oxide could be produced by direct oxidation with styrene as a coproduct. The process also led to MTBE (methyl tertiary-butyl ether), the antiknock agent used as a substitute for tetraethyl lead. 

Isocracking A hydrocracking process, developed by Chevron and now licensed by Chevron Lummus Global. The catalyst contains a mixture of hydrous oxides for cracking, plus heavy metal sulfides for hydrogenation. First commercialized in 1962 and now widely licensed worldwide. See also Isomax. 

Formulation has some influence on the resistance of composites to certain types of chemical solutions. In general, Chevron composites have about equal resistance to water, most mineral acids, and brines. In most cases, the composites have less resistance to oxidizing and basic solutions and to liquid hydrocarbons. However short-term contact can be tolerated usually without any serious detrimental effect on performance. In most circumstances, the composites have low resistance to caustic solutions, such as 5-10% NaOH. 

Among the companies which participated in developing a process starting with n-butane are Amoco, Chevron, Mobil Oil Petrotex and Standard OiL Moreover Badger, on the one hand, and Lummus/A lusuisse Italia, Standard Oil and UCB on the other, are currently developing fluidized bed n-butane oxidation processes. 

FIGURE 5.23 Comparison of Chevron s Oxidator BN results with those of ASTM sequence HID using ASTM reference oils. 

Source R. J. Robson, Base Oil Composition and Oxidation Stability, presented at the Symposium on Trends in Lube Base Stocks, Division of Petroleum Chemistry, meeting of the American Chemical Society, Philadelphia, August 26-31, 1984. Figure copyrighted by Chevron Corporation and used with permission. 

Chevron attaches considerable practical importance to the results of their in-house Oxidator BN oxidation stability test performed on base stocks to which both oxidation catalysts and inhibitors have been added. Chevron s... 

DIBROM (Chevron) (300-76-5) Degraded by UV light or sunlight. Contact with strong oxidizers, strong acids may cause fire and explosions. Hydrolyzed by water rapidly hydrolyzed in alkali solutions. Corrodes metals. 

WEED-B-GON (Chevron) (94-75-7) Decomposes in sunlight or heat above 356°F/ 180°C, forming hydrogen chloride fumes. Incompatible with strong oxidizers, alkalis. 

CCRIS 1356 EINECS 204-062-1 HSDB 175 Methylethene Methylethylene NCI-C50077 Propane 1-Propene Propylene 1-Propylene R1270 UN1077. Chemical intermediate for manufacture of isopropyl alcohol, polypropylene, synthetic glycerol, acrylonitrile, propylene oxide, heptane, cumene, polymer gasoline, acrylic xid, vinyl resins, 0x0 chemicals. Gas mp = -186.2° bp = -47.5° d = 0.505 very soluble in H2O (23 g/100 ml), EtOH, AcOH. Air Prods Chems Amoco Lubricants BP Chem. Chevron Exxon Fina Chemicals Mobil OxyChem Phillips 66 Shell Texaco. 

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