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ABSTRACT. Catalytic hydrogenation has become an important refining technique in upgrading low quality petroleum distillates to premium fuels. Prior to 1955, only a small proportion of the by-product hydrogen available from catalytic reforming was used for hydrogenation. The most common use wasand still is-pretreatment of reformer charge stocks to remove Sulfur, nitrogen, olefins and other constituents which affect the performance of platinum catalysts. The increasing demand for high octane motor gasolines has forced petroleum refiners to increase catalytic reforming capacity and to exercise less xelectivity in choosing reformer charge stocks. This has resulted in rapid expansion of hydrotreating for feedstocks preparation. Paralleling the trends in naphtha fuels, the quality requirements for midbarrel fuels are increasing, while the qualities of available crude oils are decreasing. Consequently, many refiners are now using excess reformer hydrogen to upgrade midbarrel distillates to premium fuels for internal combustion engines and to high quality burner oils. Others are employing hydrogenation to improve the qualities of catalytic cracker feeds, lube oils and waxes. The rapid growth of hydrogenation to upgrade petroleum fractions of all boiling ranges is expected to continue and to result in wider use of manufactured hydrogen to supplement by-product reformer hydrogen. Along with increased quality demands, the petroleum refiner faces an urgent need to convert residual fractions to distillate fuels. Hydrocracking appears to offer the best solution to this problem. Considerable effort is being directed toward the development of economically attractive hydrocracking processes. Commercial use of such processes in the United States is expected in the near future. Hydrogenation has become an essential part of petroleum refining technology. Whether or not engine designs of the future cause shifts in emphasis on the fuel types desired, hydrogenation will continue to play a key role in the maniifacture of premium products. RESUME. L'hydrogénation catalytique est devenue une importante technique de raffinage valorisant des pétroles de qualité inférieure en essences de première qualité. Avant 1955, une faible portion seulement de l'hydrogène de sous-produit disponible était utilisée pour l'hydrogénation. On a employé, et on le fait toujours, le traitement préliminaire des charges de stocks re réformants pour éliminer le soufre, l'azote, les oléfines et autres constituants qui affectent l'action des catalysateurs de platine. La demande croissante d'essences à haut octane a obligé les raffineurs de pétrole à augmenter la capacité de réformation catalytique et à exercer une moindre sélectivité dans le choix des charges de stocks de Sformants. I1 en est résulté une rapide expansion
- North America > United States (1.00)
- Europe (0.93)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (1.00)
- Energy > Oil & Gas > Downstream (1.00)
ABSTRACT. The coefficient of friction on the steel-steel surface lubricated by highly refined spindle oil alone or containing a very small amount of palmitic acid or cetyl alcohol is very much smaller when measured in vacuum compared to measurement in air. The coefficient has also been found to be smaller when it is measured in hydrogen, nitrogen, or carbon dioxide. These observations seem to show that scarcity of oxygen in the atmosphere surrounding the frictional surfaces lowers the friction coefficient. This phenomenon may be explained by assuming that adsorption or cliemisorption of palmitic acid or cetyl alcoliol.takes place more readily on the layer of lower iron oxide than on the layer of higher iron oxide. By repeated rubbing of the surfaces in contact during friction measurements, the layer of higher oxide covering the surfaces will partially be removed and the layer of lower oxide will become bare. This aseumption is supported by the authors' study on "film strength." For this study, three steel balls were pressed against a steel disc covered with the oil, and they were all placed in an alternating electric circuit. The "film strength" was determined by measuring the rectified electric current set up by the oil film formed between the disc and the balls. When the oil was degassed and the disc rubbed with the balls before measuring, the "film strength" increared remarkably. On the other hand, the coefficient of friction on the silver-silver surfaces lubricated by the above mentioned oil was very much larger when it was measured in vacuum, hydrogen, nitrogen, or carbon dioxide than in air. RESUME. Le coefficient de frottement entre deux surfaces d'acier lubréfiées par une huile pour broches très épurée et contenant de l'acide palmitique on de l'alcool cétylique en petite quantité, est beaucoup plus faible dans le vide que dans l'air. JI est également plus faible dans l'hydrogène, l'azote et le gaz carbonique. Ces observations montrent que la raréfaction de l'oxygène dans l'atmosphère baignant les surfaces frottantes abaisse le coefficient de frottement. On peut expliquer ce phénomène en supposant que l'adsorption ou la Sorption chimique de l'acide palmitique ou de l'alcool cétylique ont lieu plus facilement sur la conche d'oxyde ferreux que sur celle d'oxyde ferrique. Par le frottement répété dey surfaces en contact au cours des mesures, la couche d'oxyde supérienr qui recouvrait les surfaces sera en partie enlevée et la couche d'oxyde inférieur mise à nu. Cette hypothèse est 6tayée par l'étude que les auteurs ont faite de la résistance du film de lubréfiant. Pour cette étude, on a maintenu trois billes d'acier
- North America > United States (0.94)
- Asia > Japan > Kantō (0.15)
- Energy > Oil & Gas (1.00)
- Materials > Chemicals > Specialty Chemicals (0.41)
ABSTRACT. A study was made of the chemical composition of asphaltic materials and of the chemical reactions occurring when asphalts are oxidized. Three vacuum reduced residua and one hard asphalt oxidized from each of them were studied. The base stocks were chosen to represent the gel, sol-gel, and sol-type asphalts. The n-pentane insoluble asphaltenes were precipitated, and the asphaltenes further separated by fractional precipitation. The pentane soluble petrolenes from each of the six asphalts were separated into 32 fractions by chromatography and liquid thermal diffusion. The physical properties of the fractions were obtained along with 70 C, H, O, N, S, and infrared analyses. It was found that asphalts contain a significant amount of oxygen, nitrogen, and Sulfur, and should not be considered strictly hydrocarbons. The types of compounds in which these constituents occur are unknown, but carbonyl and hydroxyl groups are in evidence in the infrared spectra. The basic structural configuration is thought to be a highly substituted ring system. The substituents may be carbon from other rings, resulting in condensation, or alkyl groups most of which are short, perhaps only methyl groups. Most of the paraffinic methylene groups present are probably in one side chain containing 4 to 12 groups. These chains are shorter in oxidized asphalts and asphaltenes. The oxidation reaction is considered to be aromatization resulting from dehydrogenation of naphthenes followed by condensation. In the thermal diffusion separations it was found that non-ring carbon compounds were concentrated at the top of the column while aromatic carbon and oxygen, nitrogen, and Sulfur, were accnmula:ed at the bottom of the column. RESUME. L'étude qui suit concerne en général la composition chimique des asphaltes ainsi que leurs réactions d'oxydation; elle fut effectuée sur trois résidus, obtenus sous vide, et sur trois asphaltes durs résultant de l'oxydation de chacun des trois résidus. Les échantillons ont été choisis de façon à représenter les trois types d'asphaltes: gel, sol-gel et sol. Après précipitation première des asphaltènes n-Pentanes insolubles, la séparation plus poussée des asphaltènes fut effectuée par précipitation fractionnée. Les pétrolènes Pentanes solubles de chacun des six asphaltes furent séparés en 32 fractions par ehromotographie et diffusion thermique liquide. Les propriétés physiques de chacune des fractions, ainsi que leur teneur en C, H, O, N et S, furent détermin& et les fractions passées à l'analyseur infra-rouge. Les teneurs trou. l'hypothèse que les as] carbures. Les types de des radicaux carbonvl e rées en oxygène, azote et soufre sont suffisamment élevées pour justifier phaltes ne devraient pas être considérés comme étant uniquement des hydrocomposés formés
- Energy > Oil & Gas > Upstream (1.00)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.95)
ABSTRACT. After a brief review of the physical hardening of bitumen, which is caused by a change in structure or by loss of volatiles, the more important phenomenon of chemical hardening, due to oxidation, is dealt with extensively. The rate of oxidation is much higher in the presence than in the absence of light and the reactions are of a different type. Oxidation in the light is promoted mainly by the ultra-violet part of the spectrum and hardening is restricted to a depth of about 4 microns. In the dark, hardening may occur down to depths of 3 mm or somewhat more, which is in good agreement with a theoretical interpretation. The consequences of hardening in the dark for road construction are discussed in considerable detail. It is shown that, since the cracking of road carpets is most likely to occur under the impact of moving traffic at low temperatures, the tendency to this type of failure should be judged from the increase in stiffness of bitumens at short times of loading and at low temperatures, rather than from the increase in viscosity. Data on the hardening of a large number of bitumens are given. An accelerated test procedure for assessing the ageing characteristics of bitumens has been investigated. The acceleration is effected by increasing the oxygen pressure; it is reproducible and fairly constant. Results of this test show a satisfactory correlation with hardening data obtained from road trials. A recently published test method using acceleration by increase of temperature, appears to be practically equivalent to our method except in the case of au experimental bitumen with a large content of volatiles, where the high-temperature test gives too high a value. RESUME. Après un bref aperçu du durcissement physique du bitume provoqué par un changement dans la structure ou par la perte de substances volatiles, les auteurs traitent à fond le phénomène plus important du durcissement chimique causé par l'oxydation. La vitesse d'oxydation est beaucoup plus élevée en présence de la lumière que dans l'obscurité, et les réactions qui s'effectuent dans ces deux conditions sont d'un type différent. L'oxydation à la lumière est favorisée principalement par la partie ultra-violette du spectre et le durcissement est restreint à une profondeur d'environ 4 microns. Dans l'obscurité, le durcissement peut se produire jusqu'à des profondeurs de 3 mm ou un peu plus, ce qui s'accorde parfaitement avec l'interprétation théorique. Les conséquences du durcissement dans l'obscurité pour la construction de routes sont discutées en détail. I1 est démontré que, puisque la formation des craquelures dans le revêtement routier est selon toute probabilité le résultat des chocs reçus par le trafic à des températures basses, la tendance à produire ce type de défaut devrait être évaluée d'après l'accroissem
- Europe (1.00)
- North America > United States (0.68)
- Energy > Oil & Gas > Upstream (1.00)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.46)