Oxidation of Petroleum Oils

It is interesting indeed to look into the future with these recent developments as a background and see a great new chemical industry based on petroleum as a raw material. In fact, petroleum is a source from which many of the industrially important aliphatic compounds can be made and very probably at low cost. Some of the possibilities may be enumerated as formation of new solvents and plastics, new soaps and detergents, new flavors and perfumes, better rubber substitutes and softeners production of fuels with better properties, of lubricants having characteristics nearer the mythical ideal production of hydrogen and carbon monoxide for synthesis of compounds not possible of direct formation from hydrocarbons etc.2 

Resort is occasionally had to the addition of alkaline material to the oil undergoing treatment to react with the acids formed and thus to remove 

Temperature control and heat economy may be obtained in such liquid phase processes by using the cod oil to be treated as a medium for removing the heat generated in the reaction vessel. For this purpose, the vessel is jacketed and the cool oil circulated through the annular space before passing it into the main body of hot oil.8 

The majority of the work on the vapor phase oxidation mechanism of the hydrocarbons higher than butane has been for the purpose of studying the operation of gasoline internal combustion engines. As these studies have been largely devoted to anti-knock action a discussion may well be reserved for that section. However, some of the work is relevant. 

Wheeler and Blair 14 also formulate a process based on the hydroxylation theory for the slow oxidation of hexane after having noted the formation of large quantities of aldehydes. Callendar 18 has also obtained formaldehyde and acetaldehyde as well as higher aldehydes in the oxidation of hexane. 

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Oxidation of Petroleum Oils IR analysis determines the level of oxidation byproducts in petroleum lubricants by a general response in the carbonyl region (Fig. 16.15). The infrared area is measured over the range of 1800-1670 cm with two minima taken as the baseline correction points. The left baseline, high wave number side, is taken as the minimum over the region of 2200-2000 cm and a right... 

Fig. 59.—Type of apparatus used for oxidation of petroleum oils (James).

Improved methods of chemical treatment and solvent extraction of petroleum oils remove aromatic hydrocarbon molecules which oxidize readily to form sludge and which have high temperature coefficients of viscosity (low viscosity index). Such treatments have a secondary beneficial effect because oils so treated are more susceptible to further improvement by antioxidants and detergents. 

Chemically, creosote is a mixture of a great number of compounds, almost exclusively of cyclic structure. Individual compounds present in creosote in concentrations of 2-4% are acenaphthene, fluorene, diphenylene oxide, anthracene, and carbazole. Only one compound, phenanthrene, is present in a larger concentration (12-14%). For many years, chemists in many countries have tried tu isolate individual compounds and to find profitable uses for them. Most of these attempts have failed with exception of those involving anthracene. See also Anthracene. The principal use of creosote is for preservation of wood. Railroad lies, poles, fence posts, marine pilings, and lumber for outdoor use are impregnated with creosote in large cylindrical vessels. If properly treated, the life of the wood is greatly extended. Materials that are competitive with creosote for wood-preservation purposes include various petroleum oils, and pentachlorophenol. Pentachlorophenol is used in solutions of creosote or of petroleum oils. Blends of creosote with petroleum oils also are used for economic reasons. 

The natural oleochemicals are obtained from natural oils with the least change in the stmcture of the carbon chain fraction. In contrast, synthetic oleochemicals are built up from ethylene to the desired carbon chain fraction or from oxidation of petroleum waxes. 

Methods of analysis (ASTM D-128, IP 37) are available for the measurement of excessive acidity derived from oxidation. These methods cover conventional grease that consists essentially of petroleum oil and soap. Thus these test methods are applicable to many types but not all grease. The constituents covered by the test series are soap, unsaponifiable matter (base oil), water, free alkalinity, free fatty acid, fat, glycerin, and insoluble. A supplementary test method is also provided and is intended for application to grease that contains thickeners that are essentially insoluble in n-hexane and to grease that cannot be analyzed by conventional methods because of the presence of such constituents as nonpetroleum fluids or nonsoap-type thickeners, or both. These methods may not be applicable to grease analysis when lead, zinc, or aluminum soaps are present or in the presence of some additives such as sodium nitrite. 

Nitration of Petroleum Oils Nitration by-products can be monitored by measuring the absorbance area from the NO2 symmetric and asymmetric stretch over the range of 1650-1600 cm (Fig. 16.16). The nitration measurement uses the same general baseline as the oxidation measurement. 

Sulphation of Petroleum Oils Sulphate by-products are measured over the region of 1180-1120 cm using the general oxidation baseline. Over this region, the most probable absorption group will be either from an SO2 symmetric stretch or the SO3 stretch from C-SOb-HsO. Figure 16.16 shows examples of used petroleum engine... 

The noncatalytic partial oxidation of fuel oil converts petroleum feedstock into synthesis gas, C02, CH4, and H2S if any sulfur is present. This process has the ability to handle sulfur compounds without pretreatment (sulfur removal). Eliminating a processing step from steam reforming techniques, however, requires additional equipment for oxygen addition in the reactor. The expected carbon deposition problem with hydrocarbon material containing low H C ratios is limited by the use of carbon recovery and extinction recycle schemes [28], The partial oxidation of fuel oil typically operates at a temperature range of 1200-1500°C and pressures of 30-80 bars in a refractory-lined reactor. 

Besides the extreme complexity of the mixture resulting from the vapor phase catalytic oxidation of various petroleum fractions, there are numerous other difficulties which act as hindrances to the commercial utilization of the products. This is especially true for the utilization of tlie acids that are formed. The acids are of the aldehydic or aldehydic-hydroxy type and are present in a mixture containing aldehydes of variops molecular weights as well as unsaturated compounds. These compounds give a peculiar, objectionable odor to the acids and a brown or yellow color which is only intensified by polymerization and resinification when the acids are saponified with hot caustic solutions. The same difficulties have been encountered in the rather extensive researches being carried out, particularly in Germany, on the liquid phase, catalytic oxidation of hydrocarbon oils to fonn fatty acids. 

The natural oleochemicals are obtained from natural oils with the least change in the structure of the carbon chain fraction. In contrast, synthetic oleochemicals are built up from ethylene to the desired carbon chain fraction or from oxidation of petroleum waxes. Fats and oils are renewable products of nature. One can aptly call them oil from the sun where the sun s energy is biochemically converted to valuable oleochemicals via oleo-chemistry. Natural oleochemicals derived from natural fats and oils by splitting or trans-esterification, such as fatty acids, methyl esters, and glycerine are termed basic oleochemicals. Fatty alcohols and fatty amines may also be counted as basic oleochemicals, because of their importance in the manufacture of derivatives (6). Further processing of the basic oleochemicals by different routes, such as esterification, ethoxylation, sulfation, and amidation (Fig. 12.1), produces other oleochemical products, which are termed oleochemical derivatives. 

The base lubricant is usually a petroleum oil while the thickener usually consists of a soap or soap mixture. In addition they may contain small amounts of free alkali, free fatty acid, glycerine, anti-oxidant, extreme-pressure agent, graphite or molybdenum disulphide. 

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