JP2008297450A - Decomposition method of hydrocarbon oil - Google Patents

Abstract

Provided is a method for decomposing catalytic cracking light oil and desulfurized decanted oil which are difficult to be lightened without generating coke.
SOLUTION: At least one hydrocarbon oil selected from catalytic cracking light oil and desulfurized decanted oil is cracked at a temperature of 280 to 580 ° C. and a pressure of 2.0 to 20.0 MPa in the absence of oxygen and hydrogen. A method for decomposing a hydrocarbon oil. In the method, the hydrocarbon oil is preferably subjected to a decomposition reaction for 30 seconds to 60 minutes.
[Selection figure] None

Description

  The present invention relates to a method for cracking hydrocarbon oils, and more particularly to a method for cracking catalytic cracked light oil and desulfurized decanted oil, which are difficult to be lightened, without generating coke.

  Conventionally, crude oil is fractionated into fractions by subjecting crude oil to atmospheric distillation, vacuum distillation, etc., and each fraction is used according to its intended use. Among these fractions, heavy components having a high boiling point are lightened by catalytic cracking with a catalytic cracking device, and are blended in gasoline or the like. Here, among the fractions obtained by the catalytic cracking, the catalytic cracking gas oil is also called light cycle oil (LCO), and since it is an oil that has undergone catalytic cracking, it is very stable against the cracking reaction. It is difficult to lighten.

  Further, decanted oil (DO), which is the bottom oil of the purification tower of the catalytic cracking apparatus, is an oil mainly composed of undecomposed oil in catalytic cracking. And, since the decanted oil (DS-DO) obtained by further hydrotreating the decanted oil and removing the fine catalyst of the catalytic cracking device is heavier than the catalytic cracking light oil, Further lightening is required. However, since the desulfurized decanted oil is also oil that has undergone catalytic cracking, it is very stable against the cracking reaction, and it is difficult to make it lighter. For this reason, hydrocracking that requires a large amount of hydrogen is generally used to lighten these oils.

Further, as a method for reforming heavy oil such as oil sand, a reforming method using supercritical water (Patent Document 1) and a reforming method including a heavy carbonaceous source and water (Patent Document 2) are known. It has been.
JP-A-6-270763 JP 2002-155286 A

  As described above, catalytic cracking light oil and desulfurized decanted oil are very stable against cracking reaction and are difficult to lighten. On the other hand, coke is generated when the conditions for the decomposition reaction are made strict, for example, by raising the reaction temperature.

  Accordingly, an object of the present invention is to provide a method for decomposing catalytic cracking light oil and desulfurized decanted oil, which are difficult to lighten, without generating coke.

  As a result of intensive studies to achieve the above object, the present inventor has generated coke by cracking reaction of catalytically cracked diesel oil or desulfurized decanted oil at a specific temperature and pressure in the absence of oxygen and hydrogen. The present inventors have found that the catalytically cracked light oil or desulfurized decanted oil can be decomposed and lightened without causing the present invention to be completed.

  That is, in the hydrocarbon oil cracking method of the present invention, at least one hydrocarbon oil selected from catalytic cracking gas oil and desulfurized decanted oil is heated at a temperature of 280 to 580 ° C. and a pressure of 2 in the absence of oxygen and hydrogen. The decomposition reaction is performed under a condition of 0.0 to 20.0 MPa.

  In the hydrocarbon oil cracking method of the present invention, the hydrocarbon oil is preferably cracked for 30 seconds to 60 minutes.

  In the hydrocarbon oil cracking method of the present invention, light hydrocarbons generated at the initial stage of the cracking reaction are in a supercritical state under the above reaction conditions. Then, the supercritical light hydrocarbon surrounds and stabilizes the pyrolysis fragment generated in the pyrolysis reaction by the cage effect like a cage, thereby re-polymerizing the pyrolysis fragment. Suppress. Therefore, according to the hydrocarbon oil cracking method of the present invention, catalytic cracking light oil and / or desulfurized decanted oil can be cracked and lightened while preventing generation of coke.

The present invention is described in detail below. The hydrocarbon oil as the raw material used in the present invention is catalytic cracking light oil (LCO) and / or desulfurized decanted oil (DS-DO). Here, the catalytic cracking gas oil is a raw material of a heavy oil such as a fraction obtained by desulfurizing a crude oil atmospheric residue or a heavy gas oil fraction obtained by further vacuum distillation and desulfurization of an atmospheric residue. Is a light oil fraction obtained by catalytic cracking with a catalytic cracker, and is generally called light cycle oil (LCO) in petroleum refining. The catalytic cracking gas oil used in the present invention preferably has a sulfur content of 0 to 1.5% by mass, more preferably 0.1 to 1.0% by mass, and 0.33 to 0.75. most preferably from wt%, preferably a density (15 ° C.) is 0.90~1.20g / cm ^3, more preferably 0.92~1.10g / cm ^3, more most preferably 0.95~1.05g / cm ^3, preferably has a kinematic viscosity at 50 ° C. is ^{5.0~16.5mm 2 / s, 6.0~14.0mm 2 /} s More preferably, it is preferably 7.8 to 13.0 mm ² / s, and the 5 vol% distillation temperature is 260 to 280 ° C., and the 10 vol% distillation temperature is 290 to 310 ° C. , 90 vol% distillation temperature range of 385-405 ° C It is preferred that in.

On the other hand, desulfurized decanted oil is the bottom oil of the purification tower of the above catalytic cracking apparatus, and hydrotreating decanted oil (DO), which is mainly oil that is mainly undecomposed oil in catalytic cracking. This was obtained by removing the fine catalyst. The desulfurized decanted oil used in the present invention preferably has a sulfur content of 0.24 to 0.57% by mass and a density (15 ° C.) of 1.0 to 1.10 g / cm ^3. Preferably, the kinematic viscosity at 50 ° C is preferably 64.0 to 70.0 mm ² / s, and the 5 vol% distillation temperature is 275 to 305 ° C and the 10 vol% distillation temperature is 310 to 325 ° C. 90% by volume distillation temperature is preferably in the range of 440 to 480 ° C., and 95% by volume distillation temperature is preferably in the range of 490 to 510 ° C.

  In the hydrocarbon oil cracking method of the present invention, the hydrocarbon oil is supplied to the reaction phase, and the cracking reaction is performed in the absence of oxygen and hydrogen. In the decomposition reaction, the reaction temperature is in the range of 280 to 580 ° C, preferably in the range of 330 to 550 ° C, more preferably in the range of 380 to 500 ° C, and particularly preferably in the range of 430 to 480 ° C. The reaction pressure is in the range of 2.0 to 20.0 MPa, preferably in the range of 4.0 to 20.0 MPa, more preferably in the range of 4.0 to 18.0 MPa, and 4.0 to 16.0 MPa. The range of is particularly preferable. If the reaction temperature is too high, solid polymer (coke) will be generated even in the cracking reaction in supercritical light hydrocarbons. On the other hand, if the reaction temperature is too low, the raw hydrocarbon oil will be sufficiently lightened. Can not do it. On the other hand, if the reaction pressure is too high, it is necessary to design a high-pressure apparatus, which is not economical. On the other hand, if the reaction pressure is less than 2.0 MPa, the light hydrocarbon does not enter a supercritical state.

  In the hydrocarbon oil cracking method of the present invention, the hydrocarbon oil is preferably cracked for 30 seconds to 60 minutes under the temperature and pressure. Here, the reaction time means a holding time after reaching a predetermined temperature. If the reaction time is less than 30 seconds, the starting hydrocarbon oil cannot be sufficiently lightened. On the other hand, if the reaction time exceeds 60 minutes, over-decomposition and coking occur, and the target hydrocarbon oil This is not preferable because the yield is greatly reduced.

  The temperature condition, pressure condition, and reaction time are appropriately selected depending on the ratio of the high value-added component contained in the product that is the object of recovery. In addition, the reaction may be performed in a batch system or a flow system.

  Under the above temperature and pressure, a pyrolysis reaction and a hydrogenation reaction occur, and it is considered that light hydrocarbons are generated at the initial stage of the pyrolysis reaction. In the pyrolysis reaction, the starting hydrocarbon oil is simply pyrolyzed to lower the molecular weight, and light hydrocarbons are produced. On the other hand, in the hydrogenation reaction, H is added to the pyrolysis fragments (radicals) generated during the pyrolysis reaction of the raw hydrocarbon oil, thereby stabilizing the pyrolysis species. Here, since the light hydrocarbon generated in the initial stage of the thermal decomposition reaction is in a supercritical state under the above temperature and pressure, the light hydrocarbon in the supercritical state surrounds and stabilizes the thermal decomposition fragment by the cage effect. Therefore, repolymerization of the pyrolysis fragment is suppressed, and generation of coke can be prevented.

  In the existing technology (for example, gas phase pyrolysis, etc.), when the decomposition temperature is raised and converted in a high temperature state, the pyrolysis fragments are recombined (repolymerized), but the amount of coke generated increases. In the cracking reaction under the above temperature and pressure, the pyrolysis fragment is stabilized by the cage effect of light hydrocarbons generated at the initial stage of the cracking reaction. Absent. However, in the decomposition reaction in light hydrocarbons in a supercritical state, a solid polymer (coke) is generated at a reaction temperature exceeding 580 ° C. Therefore, in the present invention, the decomposition reaction is performed at 580 ° C. or lower.

  In addition, when supercritical water or the like is used as a solvent, the critical pressure of water is as high as 22.1 MPa, so it is necessary to design a very high pressure apparatus in accordance with such a high critical pressure. Absent. On the other hand, in the present invention, light hydrocarbons generated at the initial stage of the decomposition reaction are used as a solvent in a supercritical state, and the light hydrocarbon has a low critical pressure, so that a lower pressure apparatus can be used.

  The product obtained as described above can be separated into oil, gas, and residue such as naphtha, kerosene, light oil, and heavy oil A by general atmospheric distillation and vacuum distillation. Used as desired active ingredient.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

Example 1
As a sample, the refined tower bottom oil (DO) of the catalytic cracker (FCC) is further hydrorefined to remove the fine catalyst of the catalytic cracker, and desulfurized decanted oil (sulfur content 0.80% by mass, density) (15 ° C.): 1.0502 g / cm ³ , kinematic viscosity at 50 ° C .: 68.4 mm ² / s, 5 vol% distillation temperature: 292 ° C., 10 vol% distillation temperature: 315 ° C., 90 vol% (Tempering temperature: 460 ° C., 95% by volume distillation temperature: 498 ° C.). This desulfurized decanted oil was supplied to a reactor and reacted at a high temperature and high pressure of 450 ° C. and a pressure of 2.4 MPa for 10 minutes to decompose into gas, oil and residue. The test method was a batch method. Next, the molecular weight of the product, the carbon number distribution in FD-MS analysis, the content of components having 31 or more carbon atoms, the content of components having 14 to 30 carbon atoms, and U values of 2 and − The content of components belonging to the fraction of 6 and having 31 or more carbon atoms, the content of components belonging to the fraction of U values of 2 and -6 in the U value classification and having 14 to 30 carbon atoms, and the amount of coke produced were measured.

The molecular weight of the hydrocarbon oil is defined as being equal to the average molecular weight (Mn) measured by FD-MS. Also, the carbon number distribution is defined as one calculated from the carbon number measured by FD-MS. Moreover, the U value of the product is represented by the following formula:
MW = 14n + U
[Wherein MW is a molecular weight, n is a natural number, U is 2, 0, −2, −4, −6, −8, or −10] According to Ueda et al., Petroleum Institute Journal, 34 (1), 62 (1991); Aoyagi et al., Aromatics, vol.57, Spring, 2005, p50-56 ). Table 1 shows a comparison between desulfurized decanted oil before treatment and desulfurized decanted oil after treatment.

  From the above results, the molecular weight is decreased, the component having 31 or more carbon atoms in the FD-MS analysis is decreased, the component having 14 to 30 carbon atoms is increased, and desulfurized decanted oil is lightened. I understand. In addition, since alkane belongs to the fraction of U value 2, and alkylbenzene belongs to the fraction of U value -6, it is considered that these alkane and alkylbenzene were decomposed.

Claims (2)

  At least one hydrocarbon oil selected from catalytic cracking light oil and desulfurized decanted oil is subjected to a cracking reaction in the absence of oxygen and hydrogen under conditions of a temperature of 280 to 580 ° C. and a pressure of 2.0 to 20.0 MPa. A method for decomposing hydrocarbon oils.   The method for cracking hydrocarbon oil according to claim 1, wherein the hydrocarbon oil is subjected to a cracking reaction for 30 seconds to 60 minutes.