Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G31/00—Refining of hydrocarbon oils, in the absence of hydrogen, by methods not otherwise provided for
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C15/00—Cyclic hydrocarbons containing only six-membered aromatic rings as cyclic parts
  • C07C15/02—Monocyclic hydrocarbons
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G7/00—Distillation of hydrocarbon oils

Definitions

• This invention relates to the fractionation of hydrocarbon mixtures, especially petroleum fractions, containing aromatic, naphthenic and paraflinic hydrocarbons. More particularly the invention relates to the treatment of such mixtures to obtain fractions richer in at least one of the above hydrocarbon types than the original mixture.
• the invention is particularly suitable for the fractionation of hydrocarbon mixtures having an ASTM initial boiling point (measured on the basis of atmospheric pressure) of at least 150 C. and especially petroleum fractions boiling above 350 C.
• a hydrocarbon distillate fraction containing at least two types of hydrocarbons selected from aromatics, naphthenes and parafiins, and having an initial boiling point of at least 150 C. is vacuum redistilled at a pressure below that at Which it was originally distilled so that, as respects aromatics, naphthenes and parafiins in the fraction having the same boiling point at the original distillation pressure, the said aromatics in the fraction distil at the redistillation pressure at lower temperatures than the said naphthenes and the said naphthenes distil at the redistillation pressure at a lower temperature than the said paraffins, so that the lower boiling fractions obtained are richer in aromatics.
• the refractionation is carried out at a pressure of not more than 100 mm. Hg and preferably this pressure less than V desirably less than that of the original distillation.
• the principle may be used to effect separation of hydrocarbons by type.
• the second distillation being carried out at lower pressure, the second distillation should be carried out on narrow boiling fractions.
• the boiling range of these fractions should be of the order of the boiling point difference anticipated to occur between the various components of the feedstock due to the change in pressure.
• this separation can be improved by conducting the second, lower pressure distillation as an extractive or azeotropic distillation, i.e. in the presence of a solvent which is selective for aromatics such as, for example,
• Example 1 If it is desired to increase the yield of aromatics, or if the yield of naphthenes is unimportant, improved yields and separation of aromatics may be obtained by first subjecting the feedstock to a mild dehydrogenation treatment in known manner to convert naphthenes to aromatics. This is illustrated by the following Example 1.
• Hexa methyl cyclohexane, n-dodecane, and naphthalene have boiling points at 760 mm. Hg pressure of 212, 216.3, and 218.0 C. respectively, and they are dilficult to separate by distillation. A mixture of these components was subjected to dehydrogenation conditions so that the hexa methyl cyclohexane was converted into hexa methyl benzene, which has a boiling point at 760 mm. Hg of 263.8 C., i.e. considerably higher than that of n-dodecane or naphthalene. The dehydrogenated material was then distilled under a vacuum of mm. Hg.
• n-dodecane and naphthalene have boiling points of 91.6 and 87 .6 C. respectively, the boiling point difierence between the two being 4 C. which is considerably greater than the difference of 1.7 C. at 760 mm. Hg pressure.
• the boiling point of hexa methyl benzene at 10 mm. Hg pressure is approximately 129 C.
• n-dodecane, naphthalene and hexa methyl benzene fractions of high purity were recovered. Following the distillation, the hexa methyl benzene fraction was converted back to hexa methyl cyclohexane by hydrogenation.
• the process may be employed to separate aromatics from naphthencs or to separate each of the three types.
• aromatics naphthenes and paraffins distil in that order, aromatics concentrate in the overheads fraction and paraffins in the residue, naphthenes being removable separately as a heart out if required.
• the principle of the present invention may also be used to adjust or improve the composition and properties of petroleum fractions, particularly gas oils and lubricating oil fractions.
• EXAMPLE 2 A distillate obtained by distilling a Kuwait crude oil under the industrial pressure of 40 mm. of mercury are redistalled under the absolute pressures of 13 mm., 1 mm. and 0.001 mm. of mercury- This distillate possesses the following properties:
• the invention may therefore be applied with advantage to the production of lubricating oils because it is possible to produce, by simple distillation from a lubricating oil base stock, a variety of fractions having different hydrocarbon type distributions which can be blended as required to produce lubricating oils of desired characteristics.
• the base stock is first of all fractionated into a number of fractions by distillation under a moderate vacuum, these fractions then being redistilled under a much higher vacuum.
• This mode of operation is illustrated by the following Example 3.
• Aromatic Naphthenic Parafiinic Distillate A 18.2 19.5 62. 3
• TAB LE 8 Kinematic Distribution of hydrocarbons expressed as viscosity in percentage carbon atoms 1 Fractions centistokcs at 210 F.
• the invention may also be employed to improve the properties of gas oils. Subjecting a gas oil to a second distillation at lower pressure according to the present invention yields distillate fractions having higher specific gravity and lower pour points, cloud points and wax contents, all of which are desirable. During the second distillation, the paraffins, which are responsible for poor cold test characteristics, tend to concentrate in the residue.
• hydrocarbon distillate includes a portion of such a distillate and particularly parafiin wax separated from such a distillate.
• a parafiin wax having an oil content (ASTM D. 721) of 3.35% by weight is distilled under a vacuum of 0.001 mm. of mercury. The results obtained are shown in Table 11.
• hydrocarbon distillate mixture is a petroleum distillate having an initial boiling point above 350 C.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)

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Citations (8)

• 0
  • FR FR1332014D patent/FR1332014A/fr not_active Expired
• 1963
  • 1963-05-17 US US281340A patent/US3326799A/en not_active Expired - Lifetime

Patent Citations (8)

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