JP5219247B2 - Method for producing low sulfur cracking gasoline base and unleaded gasoline composition - Google Patents

Description

  The present invention relates to a method for producing a low-sulfur cracking gasoline base material with reduced environmental impact and an unleaded gasoline composition.

  Cracked gasoline fractions produced by cracking heavy petroleum fractions, such as catalytic cracking and thermal cracking, can be produced more economically than other gasoline bases and have a relatively high research octane number (RON) Due to the advantage of being rich in olefins, it is used as a base material for unleaded gasoline compositions. However, since the cracked gasoline fraction contains a large amount of sulfur, if a gasoline composition containing a large amount of cracked gasoline fraction is used as a fuel, it can effectively act as a NOx storage type gasoline automobile exhaust gas purification catalyst. There was a problem that I could not.

  Reduction of the sulfur content contained in the cracked gasoline fraction can be easily achieved by a known technique in which the cracked gasoline fraction is hydrotreated in the presence of high-pressure hydrogen and a catalyst. However, in that case, the hydrotreated oil obtained in such a manner is contained in the cracked gasoline fraction, and the olefin content having a relatively high RON is hydrogenated to lower the RON of the base material. In the unleaded gasoline composition which mix | blended as a base material, there existed a problem that sufficient driving | operation performance was not obtained.

  For example, (1) after sweetening a catalytically cracked gasoline having a sulfur content of 200 mass ppm or less, distilling into a light fraction having a sulfur content of 20 mass ppm or less and a heavy fraction containing the remaining sulfur content , (2) hydrodesulfurization of the heavy fraction such that the decrease in the research octane number is 3 or less and the sulfur content is 20 mass ppm or less, (3) the light fraction obtained in the step (1) The heavy fraction obtained in the step (2) and a gasoline base material other than catalytic cracking gasoline and having a sulfur content of 10 mass ppm or less are mixed, and the sulfur content is 8 mass ppm or less. A process for producing a low-sulfur gasoline comprising a process for producing a gasoline of a product has been proposed (see Patent Document 1). However, in this method, since olefin is hydrogenated and changed to paraffin, it is not possible to maintain sufficient RON and ensure practical performance.

On the other hand, by repeating a step of adsorbing a sulfur compound by contacting hydrocarbon oil with an adsorbent under specific conditions, and a step of desorbing the sulfur compound from the adsorbent by passing hydrogen through the adsorbent, There has been proposed a method in which an unnecessary reaction such as an olefin hydrogenation reaction is suppressed, and a sulfur content contained in a hydrocarbon oil serving as a gasoline base material is continuously reduced (see Patent Document 2). However, the method using such an adsorbent is also due to the specific hydrocarbon compound contained in the raw material oil, the sulfur adsorption capacity is inhibited and the sulfur content cannot be reduced efficiently and continuously. It was not always a satisfactory method.
JP 2003-183676 A JP 2003-277768 A

  As described above, a method for producing an unleaded gasoline composition that has reduced sulfur content and maintained sufficient RON to ensure practical performance has not yet been established. The present invention provides a method for producing a low-sulfur cracked gasoline base material in which sulfur content is reduced while ensuring sufficient operating performance under such circumstances, and further, an unleaded gasoline composition using the low-sulfur cracked gasoline base material The issue is to provide goods.

  As a result of diligent research to solve the above-mentioned problems, the present inventors have conducted fractionation of cracked gasoline, contacting each fraction with a catalyst containing molybdenum or tungsten in the presence of hydrogen, The present inventors have found that the sulfur content of the cracked gasoline base material can be reduced while minimizing the loss of octane number by desulfurization by appropriately combining treatments with a desulfurization agent containing nickel and zinc in the presence.

That is, the present invention
(1) A fractionation step (step A) for fractionating a cracked gasoline fraction to obtain a light cracked gasoline fraction and a heavy cracked gasoline fraction,
A hydrodesulfurization step (step B) for reducing the sulfur content by contacting the heavy cracked gasoline fraction obtained in step A with a catalyst containing molybdenum and / or tungsten in the presence of hydrogen;
All or part of the light cracked gasoline fraction obtained in step A and / or the heavy cracked gasoline fraction with reduced sulfur content obtained in step B contains nickel and zinc in the presence of hydrogen. A collecting and detaching sulfur process (process C) for contacting with a porous desulfurizing agent and reducing the sulfur content to 5 mass ppm or less,
Mixing step (step D) of mixing the cracked gasoline fraction obtained in steps A to C to obtain a low sulfur cracked gasoline base material having a sulfur content of 12 mass ppm or less and a research octane number of 85.0 or more.
It is a manufacturing method of the low sulfur decomposition gasoline base material characterized by including.

The preliminary desulfurization control coefficient α represented by the following formula (1) is 12 to 30 in the stage after the process A and the process B α = (LW × LS + HW × HS) / 100 (1)
(Where, LW is the proportion (volume%) of the light cracked gasoline fractionated in step A, LS is the sulfur content (mass ppm) in the light cracked gasoline obtained in step A, and HW is in step A. It is preferable that the fraction (volume%) of the heavy cracked gasoline fractionated and HS represents the sulfur content (mass ppm) in the heavy cracked gasoline obtained in step B.).

In the method for producing a low-sulfur cracked gasoline base material of the present invention, the ratio of supplying to the process C and treating it with respect to the total amount of cracked gasoline supplied to the process A is preferably 20% by volume or more and 90% by volume or less.
Further, before Step B or Step C, the whole or part of the cracked gasoline fraction is brought into contact with a catalyst containing at least one metal selected from Group 8 elements in the periodic table in the presence of hydrogen. It is preferable to include a diene reduction treatment step (step E) for performing the reduction treatment.
Furthermore, it is preferable to include a pretreatment step (step F) for increasing the molecular weight of the sulfur compound contained in the cracked gasoline fraction before step A or simultaneously with the fractionation step of step A.

Further, the present invention contains 30% by volume or more of the low sulfur decomposition gasoline base material produced by the above method, the research octane number is 89 or more, the sulfur content is 10 mass ppm or less, the doctor test is negative, and the silver plate corrosion is It is an unleaded gasoline composition which is 1 or less.
Furthermore, it is preferably an unleaded gasoline composition having a research octane number of 92 or more, a sulfur content of 10 mass ppm or less, a negative doctor test, and a silver plate corrosion of 1 or less.

  Various cracked gasoline fractions such as catalytically cracked gasoline fractions and pyrolyzed gasoline fractions contain a large amount of high octane olefins. The present invention appropriately combines hydrodesulfurization with a catalyst containing molybdenum or tungsten and a treatment with a porous desulfurization agent containing nickel and zinc in the presence of hydrogen to reduce the loss of olefins while minimizing olefin loss. It is possible to reduce the sulfur content. In addition, since the loss of olefin is minimal, the octane number hardly decreases, so that only the sulfur content can be reduced to 12 ppm by mass or less without changing properties such as the octane number.

[Cracked gasoline fraction]
The cracked gasoline fraction in the method for producing a low sulfur cracked gasoline base material of the present invention is a petroleum fraction, a petroleum refined process oil, a petrochemical process oil, a coal liquefied oil, an oil sand, an oil shale, a polyolefin, a plastic, A hydrocarbon compound having a lower molecular weight obtained by decomposing hydrocarbons such as waste plastics, and refers to a fraction having a carbon number of 4 or more and a boiling point of 250 ° C. or less. Typical processes for obtaining cracked gasoline fractions include catalytic cracking processes and thermal cracking processes.
The hydrocarbons such as gasoline, kerosene and light oil are decomposed to produce a fraction having a carbon number of 4 or more and a boiling point of 250 ° C. or less as a by-product from a cracking process for obtaining olefins such as ethylene and propylene. In addition, a dewaxed gasoline fraction obtained from a catalytic dewaxing process that selectively decomposes normal paraffin compounds contained in light oil or lubricating oil to improve low-temperature fluidity may be used as the cracked gasoline fraction of the present invention. it can.
In the present invention, two or more cracked gasoline fractions obtained by the above various cracking processes may be used in combination.

  As the cracked gasoline fraction in the method for producing a low sulfur cracked gasoline base material of the present invention, a catalytic cracked gasoline fraction can be preferably used. The process for producing the catalytic cracking gasoline fraction does not particularly limit the catalytic cracking apparatus, the feedstock, and the operating conditions, and any known production process can be employed. The catalytic cracker uses a catalyst such as amorphous silica alumina, zeolite, etc., in addition to petroleum fractions from light oil to vacuum gas oil, while it is obtained from the heavy oil indirect desulfurization unit, the direct desulfurization unit obtained from the degasification oil and heavy oil direct desulfurization unit. This is a device that obtains a high octane gasoline base material by catalytic cracking of degassed oil, atmospheric residue oil and the like. The raw material oil for catalytic cracking is preferably hydrogenated to a sulfur content of 8000 mass ppm or less, particularly preferably 4000 mass ppm or less, more preferably 2000 mass ppm or less, even more preferably 1000 mass ppm or less, especially 500 mass ppm or less. A fraction reduced by purification or the like is used. Specifically, the catalytic cracking method includes, for example, UOP catalytic cracking method, flexi cracking method, ultra-orthoflow method, fluid catalytic cracking method such as Texaco fluid catalytic cracking method, residual oil fluid catalytic cracking such as RCC method and HOC method. (The Japan Petroleum Institute, Petroleum Refining Process, p. 125, Kodansha Scientific (1998)).

  Moreover, a heavy oil pyrolysis gasoline fraction can also be used as a cracking gasoline fraction preferably used in the manufacturing method of the low sulfur cracking gasoline base material of this invention. A heavy oil pyrolysis gasoline fraction is a fraction having a carbon number of approximately 4 or more and a boiling point of 250 ° C. or less obtained by a reaction based on a radical reaction by applying heat to the heavy oil fraction. For example, it means a fraction obtained by a delayed coking method, a visbreaking method, a fluid coking method or the like.

[Fractionation process (Process A))
A cracked gasoline fraction, particularly a catalytic cracked gasoline fraction, contains a relatively high amount of an olefin compound having a high RON in a light fraction, but does not contain a large amount of sulfur. On the other hand, the heavy fraction contains a relatively large amount of sulfur, but does not contain many olefin compounds having a high RON. Therefore, in order to effectively use cracked gasoline fractions, particularly catalytic cracked gasoline fractions, as the base material for unleaded gasoline compositions, the sulfur content in the light cracked gasoline fraction used as the base material is sufficiently low. It is preferable to perform fractional distillation. For example, fractional distillation is performed so that the sulfur content is 20 ppm by mass or less, particularly 10 ppm by mass or less. The light cracked gasoline fraction thus obtained does not need to be subjected to a hydrodesulfurization step in which it is brought into contact with a hydrodesulfurization catalyst in the presence of high-pressure hydrogen as in step B, which will be described later. Since the compound is not hydrogenated, a reduction in RON of the light cracked gasoline fraction can be avoided. In order to increase the degree of freedom of blending the base material into the unleaded gasoline composition, at least one of the light cracked gasoline fraction and the heavy cracked gasoline fraction is further fractionated and subdivided, and the cracked gasoline fraction is divided into three or more. You may fractionate into fractions. And the hydrodesulfurization process (process B) mentioned later is implemented with respect to the heavy cracked gasoline fraction containing comparatively much sulfur content. Thereby, the load to the collection / removal sulfur process (process C) mentioned later can be reduced, and desulfurization can be performed economically.

Preferred properties of the fractionated light cracked gasoline fraction are 5% distillation temperature of 35-55 ° C, especially 40-50 ° C, 95% distillation temperature of 65-125 ° C, especially 75-115 ° C. Yes, the sulfur content is 1 to 50 ppm, particularly 5 to 20 ppm, and the olefin content is 30 to 70% by volume, particularly 40 to 60% by volume. The heavy cracked gasoline fraction is a heavier fraction than the light cracked gasoline fraction, and usually has a higher sulfur content and a lower olefin content than the light cracked gasoline fraction. Preferred properties of the fractionated heavy cracked gasoline fraction are 5% distillation temperature of 80-170 ° C, especially 95-160 ° C, 95% distillation temperature of 175-215 ° C, especially 190-220 ° C. The sulfur content is 20 to 500 ppm, particularly 50 to 300 ppm, and the olefin content is 1 to 35% by volume, particularly 5 to 25% by volume.
The fractionation step fractionates a cracked gasoline fraction obtained from a cracking process such as a catalytic cracking process. The fractionation step includes a light cracking gasoline fraction directly from a fractionation step included in the final stage of the cracking process. Heavy cracked gasoline fractions can also be obtained.

[Hydrodesulphurization process (Process B)]
Step B is a step in which the heavy cracked gasoline fraction obtained in Step A and the hydrodesulfurization catalyst are brought into contact with each other in the presence of high-pressure hydrogen to separate the sulfur as hydrogen sulfide and hydrodesulfurize. The heavy cracked gasoline fraction contains a relatively large amount of sulfur, so to supply low sulfur gasoline, the heavy cracked gasoline fraction is usually all hydrodesulfurized, but most of it, Specifically, it is preferable to hydrodesulfurize 80% by volume or more, particularly 90% by volume or more. By the hydrodesulfurization step, the sulfur content of the heavy cracked gasoline fraction can be 5 to 50 ppm, preferably 10 to 30 ppm.

  The hydrodesulfurization catalyst contains molybdenum and / or tungsten, and preferably has molybdenum or tungsten supported on an inorganic porous carrier such as alumina. The hydrodesulfurization catalyst preferably has a total content of molybdenum and tungsten of 2 to 20 mass%, particularly 5 to 15 mass%. Content is prescribed | regulated by the mass% of the metal element contained in a catalyst. There are no particular restrictions on the component elements other than molybdenum or tungsten contained in the catalyst, but preferred components that may be included include cobalt, phosphorus, potassium, carbon, nitrogen, and the like. It is preferable that the cobalt content is 0.5 to 10% by mass, particularly 1 to 5% by mass, and the phosphorus content is 0.2 to 10% by mass, and particularly 0.5 to 5% by mass. Usually, the catalyst is used after the sulfurization treatment.

Preferred reaction conditions are a reaction temperature of 150 to 350 ° C., a reaction pressure of 0.1 to 4.0 MPa, a liquid space velocity (LHSV) of 1.0 to 10 h ⁻¹ , and a hydrogen / oil ratio of 50 to 1000 NL / L. Particularly preferable reaction conditions are a reaction temperature of 200 to 300 ° C., a reaction pressure of 0.5 to 2.5 MPa, an LHSV of 2.0 to 6.0 h ⁻¹ , and a hydrogen / oil ratio of 100 to 600 NL / L. In addition, the reaction pressure in this specification is shown with a gauge pressure. The heavy cracked gasoline fraction does not contain a relatively large amount of olefin compound having a high RON, but when hydrogenated, the olefin compound may be saturated and RON may be lowered. % Or more, more preferably 10% or more, particularly 3% or more is not preferable.

  In Step B, hydrogen sulfide produced by hydrodesulfurization reacts with the olefins normally contained in cracked gasoline to produce thiols, but if thiols are contained in gasoline, it will cause corrosion of car parts and bad odor. It is not preferable. The thiols in the cracked gasoline that has undergone the process B are removed when the process C described later is performed, but when the process C is not performed, the thiols are preferably removed. Although this removal method is not particularly limited, it is preferable to remove thiols by a method of converting thiols typified by oxidation-type sweetening into disulfides. Furthermore, the thiols contained in the heavy cracked gasoline usually have about 5 to 10 carbon atoms, and it is preferable to apply an oxidation-type sweetening process that can remove even thiols having a large carbon number. Specific examples include the MERICAT-II process described in NPRA 2000 Annual Meeting AM-00-54. The details of such sweetening will be described later as a method for increasing the molecular weight of the sulfur compound. As another removal method, it is preferable to reduce the thiols in the gasoline base material in advance so that the sulfur content of the thiols in the lead-free gasoline composition is 2 ppm by mass or less, and further 1 ppm by mass or less.

[Accumulation and removal sulfur process (process C)]
In the present invention, after performing Step A and Step B, desulfurization agent containing nickel and zinc in the presence of hydrogen and various cracked gasoline fractions obtained in Step A and Step B, that is, obtained in Step A. The obtained light cracked gasoline fraction and heavy cracked gasoline fraction and the heavy cracked gasoline fraction obtained in step B are brought into contact with each or all or a part thereof, and the sulfur content is 5 mass. A collecting / removing sulfur process (process C) for desulfurization to ppm or less, preferably 1 mass ppm or less is performed.

In addition, in the stage which passed through the process A and the process B, 12-30 are preferable and, as for the preliminary | backup desulfurization control coefficient (alpha) represented by following Formula (1), 13-20 are more preferable.
α = (LW × LS + HW × HS) / 100 (1)
In the formula, LW is the ratio (volume%) of the light cracked gasoline fraction fractionated in step A, LS is the sulfur content (mass ppm) in the light cracked gasoline fraction obtained in step A, and HW is The ratio (volume%) of the heavy cracked gasoline fraction fractionated in Step A, and HS represents the sulfur content (mass ppm) in the heavy cracked gasoline fraction obtained in Step B. The ratio of the light cracked gasoline fraction and the ratio of the heavy cracked gasoline fraction are the ratio to the capacity of 100% by volume of the cracked gasoline fractionated in the process A. The ratio HW of the heavy cracked gasoline fraction fractionated in step A is preferably 10 to 80% by volume, particularly 25 to 60% by volume.
Thereby, since it does not hydrogenate more than necessary while desulfurizing moderately, RON fall can be controlled to the minimum and desulfurization can be performed economically. If the preliminary desulfurization control coefficient α is less than 12, the decrease in RON becomes large, which is not preferable. When α exceeds 30, the raw material sulfur concentration becomes high in Step C, and the life of the desulfurizing agent containing nickel and zinc is shortened, which is not preferable.

  Hydrocracking a cracked gasoline fraction in the presence of a hydrodesulfurization catalyst and hydrogen to desulfurize it to a sulfur content of 5 ppm by mass or less is preferable because the RON of the gasoline base obtained by hydrogenating the olefin is reduced. Absent. Furthermore, since hydrogen sulfide generated by hydrodesulfurization reacts with olefins to regenerate thiols, it is not preferable because it cannot be sufficiently desulfurized. When a porous desulfurization agent containing nickel and zinc is used in the presence of hydrogen, the sulfur removed from the organic sulfur compound is immobilized on the desulfurization agent and does not generate hydrogen sulfide, so it reacts with olefins to regenerate thiols. There is nothing to do.

The feedstock oil used in Step C is the whole or part of the light cracked gasoline fraction obtained in Step A or the heavy cracking obtained by contacting with a hydrodesulfurization catalyst in the presence of high-pressure hydrogen in Step B. Use all or part of the gasoline fraction. Or what mixed each in the appropriate ratio may be used.
When the light cracked gasoline fraction obtained in Step A is used in Step C, 30 to 100% by volume of the light cracked gasoline fraction is preferably used as the feedstock. When the heavy cracked gasoline fraction obtained in Step B is used in Step C, it is preferable to use 30 to 100% by volume of the heavy cracked gasoline fraction as a feedstock.

  It is preferable that the ratio of processing in Step C is 20% by volume or more and 90% by volume or less, and particularly 25% by volume or more and 70% by volume or less with respect to the total amount of cracked gasoline before being used in Step A. If the ratio of treatment in Step C is less than 20% by volume, a sufficient effect of suppressing the decrease in octane number cannot be obtained. If the ratio of treatment in Step C exceeds 90% by volume, the life of the desulfurizing agent containing nickel and zinc is shortened, which is not preferable.

The porous desulfurizing agent of the present invention contains nickel and zinc. The production method of the porous desulfurization agent containing nickel and zinc in the present invention is not particularly limited, but a production method in which a porous carrier such as alumina is impregnated with a metal component such as zinc or nickel, supported and fired, or coprecipitation A preferable method is a production method in which a metal component such as zinc or nickel is precipitated by a method, filtered and washed, and subjected to steps such as molding and firing. In addition to nickel and zinc, other elements such as iron and copper may be included. The element mass ratio of nickel to zinc is preferably 1 to 50 mass%, particularly preferably 2 to 35 mass% or less, and more preferably 5 to 30 mass% with respect to 100 mass% of the total element mass of zinc and nickel. is there. The nickel content is preferably 33% by mass or less, more preferably 20% by mass or less, based on the total mass of the desulfurizing agent. The zinc content is preferably 30% by mass or more, more preferably 50% by mass or more, and particularly preferably 55% by mass or more with respect to the total mass of the desulfurizing agent. If the nickel content exceeds 50% by mass or the zinc content is less than 30% by mass, the life of the porous desulfurization agent is shortened, which is not preferable. The sodium content is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, and further 0.2% by mass or less with respect to the total mass of the desulfurizing agent. If sodium exceeds 1.0 mass% with respect to the total mass of the desulfurizing agent, the desulfurization performance is lowered, which is not preferable. A preferable desulfurizing agent contains 30 to 85% by mass, particularly 50 to 80% by mass of a metal component such as nickel or zinc. Alternatively, the molded and fired desulfurizing agent may be further impregnated and supported with a metal component and fired. The desulfurizing agent is preferably used after being treated in a hydrogen atmosphere. The specific surface area of the desulfurizing agent is preferably ^{30 m} 2 / g or more, particularly preferably 50 to 600 m ² / g.

  The porous desulfurization agent of the present invention is preferably a porous desulfurization agent having a sulfur sorption function. The porous desulfurization agent having a sulfur sorption function here is to fix sulfur atoms in the organic sulfur compound to the desulfurization agent, and for hydrocarbon residues other than sulfur atoms in the organic sulfur compound, A porous desulfurization agent having a function of desorbing from a desulfurization agent by cleavage of a carbon-sulfur bond in a sulfur compound. When this hydrocarbon residue is eliminated, hydrogen present in the system is added to carbon whose bond with sulfur has been cleaved. Therefore, a hydrocarbon compound obtained by removing sulfur atoms from the organic sulfur compound is obtained as a product. However, the hydrocarbon compound from which the sulfur atom is removed may give a product that has undergone a reaction such as hydrogenation, isomerization, or decomposition. In the detachable sulfur, sulfur is fixed to the desulfurizing agent, and therefore, unlike hydrorefining, a sulfur compound such as hydrogen sulfide is not generated as a product. Furthermore, since hydrogen sulfide is not generated, hydrogen sulfide is not contained in the recycled hydrogen or purge hydrogen, and no facility for removing hydrogen sulfide is required, so that desulfurization can be achieved economically.

  The collection / removal sulfur treatment may be performed in a batch system or a flow system, but is performed by circulating a light cracked gasoline fraction or a heavy cracked gasoline fraction through a fixed bed desulfurization tower filled with a desulfurizing agent. It is preferable that the desulfurization agent and the obtained desulfurized cracked gasoline fraction can be easily separated. The temperature in the desulfurization treatment is preferably 100 to 400 ° C, more preferably 200 to 350 ° C, and particularly preferably 250 to 350 ° C. When the reaction temperature is less than 100 ° C., the desulfurization rate decreases, and it is not preferable because desulfurization cannot be efficiently performed. On the other hand, when the reaction temperature exceeds 400 ° C., the desulfurization agent is sintered, and the desulfurization capacity is lowered, which is not preferable. Hydrogen is allowed to coexist in order to promote desulfurization of thiophenes that are difficult to desulfurize only by contacting with a desulfurizing agent. The reaction pressure is preferably 0 to 5.0 MPa, more preferably 0 to 3.0 MPa, and particularly preferably 0 to 2.0 MPa. When the reaction pressure exceeds 5.0 MPa, hydrogenation of the olefin contained in the hydrocarbon oil is likely to proceed, and RON may be lowered.

If fixed bed flow contacting the cracked gasoline fraction and desulfurizing agent performs desulfurization treatment, LHSV is preferably not more than 50.0H ^-1 exceed 2.0 h ^-1, more preferably 2.0 h ^- is ¹ to greater than 20.0H ^-1 or less, particularly preferably not more than 10.0H ^-1 exceed 2.0 h ^-1. If the LHSV is 2.0 h ⁻¹ or less, the amount of oil passing is limited, the desulfurization reactor becomes too large, and it is not preferable because it cannot economically desulfurize. If the LHSV exceeds 50.0 h- ¹ , contact time sufficient for desulfurization cannot be obtained, and the desulfurization rate decreases, which is not preferable. Further, when the desulfurization treatment is performed by contacting the desulfurization agent and the cracked gasoline fraction in a fixed bed flow type in the presence of hydrogen, the hydrogen / oil ratio is preferably 1 to 1000 NL / L, more preferably 10 to 500 NL / L. L, particularly preferably 10 to 300 NL / L. The hydrogen may contain impurities such as methane, but the hydrogen purity is preferably 50% by volume or more, more preferably 80% by volume or more, and particularly 95% by volume or more so that the hydrogen compressor does not become too large. . When a sulfur compound such as hydrogen sulfide is contained in hydrogen, the life of the desulfurizing agent is reduced, so that the ratio is preferably a certain ratio or less. Specifically, the sulfur content in hydrogen is preferably 1000 ppm by volume or less, more preferably 100 ppm by volume or less, and particularly preferably 10 ppm by volume or less.

[Mixing step (Step D): Preparation of low sulfur cracking gasoline base material]
In the mixing step (step D), the cracked gasoline fraction is processed in step A, step B, and step C, the base materials obtained in each step are mixed, the sulfur content is 12 mass ppm or less, and RON is 85. Prepare zero or more low sulfur cracking gasoline base. The sulfur content is preferably 10 mass ppm or less, and more preferably 8 mass ppm or less. RON is preferably 89.0 to 93.0. In addition, the various base materials obtained in Step A, Step B, and Step C are used in a well-balanced manner so that the production amount and the amount used in Step D for preparing the low sulfur decomposition gasoline base material are not excessive or insufficient. It is economical and preferable.

  Typically, the light cracked gasoline fraction obtained in step A and treated in step C is mixed with the heavy cracked gasoline fraction obtained in step A and treated in step B, or in step A The obtained light cracked gasoline fraction is mixed with the heavy cracked gasoline fraction obtained in step A, treated in step B, and further treated in step C. It is preferable to mix various base materials obtained from almost the entire amount of the cracked gasoline fraction used as the raw material of step A, for example, 80% by volume or more to obtain a low sulfur cracked gasoline base material. Moreover, you may perform the mixing of the process D simultaneously with the below-mentioned blending process which is mixing with the other gasoline base material for preparation of a gasoline composition.

[Diene reduction treatment process (Process E)]
In the method for producing a cracked gasoline base material of the present invention, the whole or part of the cracked gasoline fraction in the presence of hydrogen in the step B or the step C, preferably in an inorganic porous carrier such as alumina, It is preferable to reduce the diene value by contacting with a catalyst supporting at least one metal selected from Group 8 elements. Since the cracked gasoline fraction contains a sulfur content, a catalyst containing nickel or cobalt having high resistance to the sulfur content is preferable. There are no particular restrictions on the active component elements other than the Group 8 element contained in the catalyst, but molybdenum, tungsten, and phosphorus are listed as preferred components that may be included. Usually, the catalyst is used after the sulfurization treatment. The reaction conditions are such that the diene number of the cracked gasoline fraction to be obtained is reduced, but it is necessary to set the olefin hydrogenation so as not to significantly reduce RON.

Preferred reaction conditions are a reaction temperature of 40 to 300 ° C., a reaction pressure of 0 to 4 MPa, an LHSV of ¹ to 10 h ⁻¹ , and a hydrogen / oil ratio of ¹ to 500 NL / L. The diene value of the cracked gasoline fraction obtained by step E is preferably 0.5 g / 100 g or less, more preferably 0.3 g / 100 g, and particularly preferably 0.1 g / 100 g or less. If the diene value exceeds 0.5 g / 100 g, the desulfurization performance and the life of the desulfurizing agent are greatly impaired in Step B and Step C, which is not preferable. Further, in step E, the decrease in olefin content is preferably 10% by volume or less, particularly preferably 5% by volume or less, more preferably 2% by volume or less, and the decrease in RON is preferably 1 or less, more preferably 0. 0.5 or less, more preferably 0.3 or less, particularly preferably 0.2 or less. In the diene reduction treatment stage, the sulfur content is not substantially reduced. A part of the sulfur content may be converted to hydrogen sulfide, which may be desulfurized in the subsequent step B or step C, and it is economical to provide hydrogen sulfide removal equipment in the diene reduction treatment step. It doesn't match. The diene value as used in the field of this invention refers to the diene value measured by UOP326-82.

  The diene value is reduced by contacting the catalyst and catalytically cracked gasoline in the presence of hydrogen to convert the diene to a monoolefin, or reacting the sulfur compound coexisting with the diene to convert it to sulfides. By using the catalyst containing a Group 8 element and applying the above-mentioned preferable reaction conditions, hydrogenation of the olefin can be almost suppressed, so that the diene value can be reduced without significantly reducing RON.

  Conventionally, in petroleum refining, diene in olefins has been selectively hydrorefined and can be applied as step E in the present invention. Specifically, the IFP Selective Hydrogenation process, the Hules Selective Hydrogenation process, and the like are preferably used (edited by the Petroleum Society, Petroleum Refining Process, p. 62, Kodansha Scientific (1998)). In addition, as a method for reducing the diene value in the present invention, the SHU process (21st JPI Petroleum Refining Conference “Recent Progress in Petroleum Process Technology”, 37 (2002)) and the CD Hydro process (NPRA 2001 Annual Meeting, AM-01-39) (2001)) can also be used.

[Pretreatment step for increasing the molecular weight of the sulfur compound (Step F)]
The cracked gasoline fraction is subjected to a pretreatment step (step F) for increasing the molecular weight of the sulfur compound contained therein and used for the fractionation step of step A, or the molecular weight of the sulfur compound is increased simultaneously with the fractionation step of step A. It is preferable to perform a pretreatment. By selectively increasing the molecular weight of sulfur compounds such as thiols, the boiling point of the sulfur-containing compound increases, so that the sulfur-containing compound can be transferred into the heavy cracked gasoline fraction during the fractionation process. The sulfur content of the light cracked gasoline fraction obtained in the fractionation step can be reduced. For example, a catalyst is placed in a distillation column to make the sulfur content heavy, and the heavy sulfur compound is transferred to the distillate component on the heavy side to reduce the sulfur content of the light fraction. be able to. The CD-Hydro process described later uses this.

  Conventionally, in petroleum refining, sweetening for treating thiols to make the product non-brominated is performed. A known method for converting a thiol to a disulfide by an oxidation method or an oxidation extraction method can be applied as a method for increasing the molecular weight of a sulfur compound in the present invention. Specifically, the Marlox method, the doctor method, etc. are preferably used (Oil Refinery Technical Handbook 3rd Edition, Sangyo Tosho Co., Ltd. (1981)).

  In the present invention, as a method of increasing the molecular weight of the sulfur compound, a method of reacting the sulfur compound and olefins contained in the cracked gasoline fraction can also be suitably used. Specific examples include the SHU process and OATS process (21st JPI Petroleum Refining Conference “Recent Progress in Petroleum Process Technology”, 37 (2002)). In particular, an SHU process capable of simultaneously performing a treatment for increasing the molecular weight of a sulfur compound and a diene reduction treatment is preferable. Furthermore, a process capable of simultaneously performing a treatment for increasing the molecular weight of the sulfur compound and a diene reduction treatment while performing fractional distillation is more preferable. Specific examples of such a process include a CD-Hydro process.

[Other gasoline base materials other than cracked gasoline fraction]
Other gasoline base materials other than the cracked gasoline fraction mixed in the blending process, which is the final step for preparing a low sulfur gasoline composition, include catalytic reformed gasoline base materials, alkylate gasoline base materials, and direct distillation. Base material obtained by desulfurizing naphtha, isomerized gasoline base, aromatic base such as toluene and xylene, and methyl t-butyl ether (MTBE), ethyl t-butyl ether (ETBE), t-amyl ethyl ether (TAEE), Known gasoline base materials such as oxygen-containing gasoline base materials such as ethanol and methanol can be appropriately used. In particular, ETBE is a preferable base material that has a higher octane number improvement effect per oxygen content than ethanol and MTBE, and can increase the octane number without deteriorating volatility by ETBE mixing.

The other gasoline base material mixed in the blending step preferably has a sulfur content of 20 ppm by mass or less, more preferably 10 ppm by mass or less, further 3 ppm by mass or less, and particularly 1 ppm by mass or less. If the sulfur content of the other gasoline base exceeds 20 mass ppm, the blending amount in the blending step of the gasoline base is restricted, which is not preferable.
Preferred blending amounts are 30 to 90% by volume of cracked gasoline fraction, particularly 40 to 80% by volume, 5 to 50% by volume of catalytically reformed gasoline base, particularly 10 to 45% by volume, alkylate gasoline base 5 to 40% by volume, particularly 10 to 30% by volume, and 0 to 16% by volume, particularly 1 to 7% by volume, of an oxygen-containing gasoline base material such as ETBE.

[Gasoline composition]
The unleaded gasoline composition of the present invention has a research octane number of 89.0 or more, a total sulfur content of 10 mass ppm or less, a negative doctor test, and a silver plate corrosion of 1 or less. The research octane number is preferably 90.0 or more and the diene value is preferably 0.1 g / 100 g or less. If the doctor test is positive or the silver plate corrosion exceeds 1, unpleasant odors are generated from gasoline and corrosion of members used in gasoline automobiles is not preferable. RON is preferably 92 or more, more preferably 93 to 102. Having such a high RON is preferable because it can improve the acceleration performance and fuel consumption of a gasoline automobile. Further, the sulfur content is preferably 8 ppm by mass or less, more preferably 5 ppm by mass or less.

  The unleaded gasoline composition of the present invention preferably has a Reed vapor pressure (RVP) of 93 kPa or less, more preferably 44 to 93 kPa. If it exceeds 93 kPa, the amount of gasoline vapor released into the atmosphere increases, which is not preferable. If it is less than 44 kPa, the startability of the gasoline automobile is deteriorated, which is not preferable. More preferably, the RVP is adjusted according to the season, and it is preferably 44 to 65 kPa in summer and 70 to 93 kPa in winter.

The unleaded gasoline composition of the present invention preferably has a 50% by volume distillation temperature of 75 to 105 ° C, more preferably 75 to 100 ° C. If the 50% by volume distillation temperature is less than 75 ° C., the RVP of the unleaded gasoline composition increases, which is not preferable. If it exceeds 105 ° C., the acceleration performance of the gasoline vehicle deteriorates, which is not preferable. The aromatic content is preferably 40% by volume or less, more preferably 30% by volume or less, and particularly preferably 20 to 30% by volume. If the aromatic content is less than 20% by volume, the blending amount of the cracked gasoline base material is limited, and the production cost of the unleaded gasoline composition becomes high, which is not preferable. If it exceeds 40% by volume, the flammability of the unleaded gasoline composition deteriorates, which is not preferable.
Furthermore, the olefin content, which is the ratio of the unsaturated carbon number to the total carbon number, is preferably 45% by volume or less, more preferably 20 to 40% by volume, and particularly preferably 20 to 30% by volume. When the ratio of the unsaturated carbon number to the total carbon number is in such a range, it becomes easy to secure the olefin content and aromatic content in the above range.

〔Additive〕
In the unleaded gasoline composition of the present invention, one or more fuel oil additives known in the art can be blended as required. Although these compounding quantities can be selected suitably, it is preferable to maintain the total compounding quantity of an additive to 0.1 mass% or less normally. Examples of fuel oil additives that can be used in the gasoline of the present invention include phenolic, amine-based antioxidants, Schiff-type compounds, metal deactivators such as thioamide-type compounds, and organic phosphorus-based surfaces. Anti-ignition agent, detergent / dispersant such as succinimide, polyalkylamine, polyetheramine, anti-icing agent such as polyhydric alcohol or its ether, alkali metal salt or alkaline earth metal salt of organic acid, sulfuric acid of higher alcohol Examples include an auxiliary combustor such as an ester, an anionic surfactant, a cationic surfactant, an antistatic agent such as an amphoteric surfactant, and a colorant such as an azo dye.

  Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

  Contact obtained by fluid catalytic cracking using a hydrorefining treatment of a vacuum gas oil fraction of Middle Eastern crude oil and a hydrorefining treatment of atmospheric distillation residue oil as the main feed oil (sulfur content 3,500 ppm) The cracked gasoline fraction A was treated by an oxidation type sweetening device to obtain a catalytic cracked gasoline fraction B. Table 1 shows the properties of the catalytic cracking gasoline fractions A and B. The oxidation type sweetening apparatus was a Merox process manufactured by UOP, and was operated at a reaction temperature of 42 ° C.

  In this specification, the density is JIS K 2249, the vapor pressure (Lead method) is JIS K 2258, the distillation property is JIS K 2254 (normal pressure method), the hydrocarbon component composition is JIS K 2536 (fluorescent indicator adsorption method), The diene value was measured according to UOP326-82, and the sulfur content was measured according to ASTM D 5453 (ultraviolet fluorescence method). RON was measured by a gas chromatograph method using a PIONA device manufactured by Hewlett-Packard Company. Silver plate corrosion is the cylinder method (jet fuel) of JIS K2513 (Petroleum products-Copper plate corrosion test method: corresponding ASTM D130). Instead of the copper plate, “14. Silver plate of JIS K2276 (Petroleum product-Aviation fuel oil test method)” The silver plate used in the “corrosion test method” was evaluated. The test temperature is 50 ° C. and the test time is 3 hours. The doctor test was measured according to JIS K 2276.

  This catalytic cracking gasoline fraction B was fractionated to obtain a light catalytic cracking gasoline fraction C and a heavy catalytic cracking gasoline fraction D. The ratio of the light fraction C and the heavy fraction D was 68:32 (volume ratio). Table 1 shows the properties of the light catalytic cracking gasoline fraction C and the heavy catalytic cracking gasoline fraction D.

A catalyst in which 20% by mass of nickel is supported on alumina is charged into a fixed bed flow reactor and subjected to sulfidation, followed by reaction temperature of 250 ° C., reaction pressure and pressure, LHSV = 4.0 h ⁻¹ , hydrogen / oil ratio of 340 NL / Under conditions of L, light catalytic cracking gasoline fraction C was passed through and diene reduction treatment was performed to obtain light catalytic cracking gasoline E.

A solution obtained by dissolving 106 g of sodium carbonate in water was heated to 60 ° C., and a solution obtained by adding 58 g of nickel nitrate hexahydrate to a solution obtained by dissolving 179 g of zinc nitrate hexahydrate in water was added dropwise thereto. The resulting precipitate was filtered and washed with water. Then, after drying at 120 ° C. for 16 hours, calcination was performed at 350 ° C. for 3 hours to obtain a desulfurizing agent Z. The desulfurizing agent Z had a nickel content of 17.9% by mass, a zinc content of 58.7% by mass, a sodium content of 0.02% by mass and a specific surface area of 80 m ² / g. Moreover, the ratio of nickel to zinc was 30.4% by mass. Light catalytic cracking gasoline fraction E is desulfurized using a desulfurizing agent Z under the conditions of a reaction temperature of 300 ° C., a reaction pressure of normal pressure, LHSV = 2.5 h ⁻¹ , and a hydrogen / oil ratio of 180 NL / L. F was obtained. Properties of light catalytic cracking gasoline fractions E and F are shown in Table 1.

A catalyst having cobalt, molybdenum and phosphorus supported on alumina (cobalt content 2.4% by mass, molybdenum content 9.4% by mass, phosphorus content 2.0% by mass) was charged into a fixed bed flow reactor. After sulfiding, the heavy catalytic cracking gasoline fraction D was passed through under conditions of reaction temperature 225 ° C., reaction pressure 1.0 MPa, LHSV = 5.0 h ⁻¹ , hydrogen / oil ratio = 307 NL / L. Hydrodesulfurization was carried out and further treated with an oxidation type sweetening device to obtain heavy catalytic cracked gasoline G. The oxidation type sweetening apparatus was a MERICAT-II process manufactured by Merichem, and was operated at a reaction temperature of 41 ° C.
All the light catalytic cracking gasoline F and the heavy catalytic cracking gasoline G were mixed to obtain a low sulfur cracking gasoline base H. Table 1 shows the properties of the heavy catalytic cracking gasoline G and the low sulfur cracking gasoline base H. The value of the preliminary desulfurization control coefficient α in Example 1 was 18. In addition, since the sulfur content does not change before and after sweetening, hydrodesulfurization of heavy catalytic cracking gasoline fraction D is performed, and then the sulfur content of heavy catalytic cracking gasoline G after sweetening is used as HS for predesulfurization control. The coefficient α was calculated.

Half of the light catalytic cracking gasoline fraction C obtained in the same manner as in Example 1 was subjected to diene removal treatment and desulfurization treatment with a desulfurizing agent Z in the same manner as in Example 1 to obtain light catalytic cracking gasoline F. .
A heavy catalytic cracking gasoline fraction D obtained in the same manner as in Example 1 was prepared by using a catalyst in which cobalt, molybdenum and phosphorus were supported on alumina (cobalt content 2.4% by mass, molybdenum content 9.4% by mass). , Phosphorus content of 2.0 mass%) was charged into a fixed bed flow reactor and subjected to sulfiding treatment, then reaction temperature was 240 ° C., reaction pressure was 1.0 MPa, LHSV = 5.0 h ⁻¹ , hydrogen / oil ratio = Under conditions of 307 NL / L, hydrodesulfurization was carried out by passing oil, and further treated with an oxidation type sweetening device to obtain heavy catalytic cracked gasoline I.
A half amount of light catalytic cracking gasoline C, a total amount of light catalytic cracking gasoline F, and a total amount of heavy catalytic cracking gasoline I were mixed to obtain a low sulfur cracking gasoline base J. Table 2 shows the properties of the low sulfur cracking gasoline base material J and the properties of the related intermediate base material. The preliminary desulfurization control coefficient α in Example 2 was 14.

Using a desulfurizing agent Z, the total amount of heavy catalytic cracked gasoline G obtained by the same method as in Example 1 was used, reaction temperature 300 ° C., reaction pressure 0.5 MPa, LHSV = 2.5 h ⁻¹ , hydrogen / oil ratio 20 NL. A heavy catalytic cracking gasoline K was obtained by desulfurization treatment under the conditions of / L. A light sulfur cracked gasoline C total amount and a heavy catalytic cracked gasoline K total amount obtained in the same manner as in Example 1 were mixed to obtain a low sulfur gasoline base material L. Table 3 shows the properties of the low-sulfur cracking gasoline base L and the properties of the related intermediate base. The preliminary desulfurization control coefficient α in Example 3 was 18.

The catalytic cracking gasoline fraction B obtained in Example 1 was subjected to fractional distillation so that the volume ratio was 47:53 to obtain a light catalytic cracking gasoline fraction M and a heavy catalytic cracking gasoline fraction N.
A catalyst having cobalt, molybdenum and phosphorus supported on alumina (cobalt content 2.4% by mass, molybdenum content 9.4% by mass, phosphorus content 2.0% by mass) was charged into a fixed bed flow reactor. After sulfurization treatment, heavy catalytic cracking gasoline fraction N was passed through under conditions of reaction temperature 225 ° C., reaction pressure 1.0 MPa, LHSV = 5.0 h ⁻¹ , hydrogen / oil ratio = 307 NL / L. Hydrodesulfurization was carried out and further treated with an oxidation type sweetening device to obtain heavy catalytic cracked gasoline O.
Half of the heavy catalytic cracked gasoline O was subjected to desulfurization treatment with the desulfurizing agent Z to obtain heavy catalytic cracked gasoline P.
A total amount of light catalytic cracking gasoline M, a half amount of heavy catalytic cracking gasoline O, and a total amount of heavy catalytic cracking gasoline P were mixed to obtain a low sulfur cracking gasoline base material Q. Table 4 shows the properties of the low sulfur decomposition gasoline base material Q and the related intermediate base material. The preliminary desulfurization control coefficient α in Example 4 was 14.

Comparative Example 1

The heavy catalytic cracking gasoline fraction D obtained in Example 1 was prepared from a catalyst in which cobalt, molybdenum and phosphorus were supported on alumina (cobalt content 2.4 mass%, molybdenum content 9.4 mass%, phosphorus content 2.0 mass%) was charged into a fixed bed flow reactor and subjected to sulfurization treatment, and then the reaction temperature was 300 ° C., the reaction pressure was 3.0 MPa, LHSV = 5.0 h ⁻¹ , and the hydrogen / oil ratio was 307 NL / L. Under conditions, the oil was passed through and hydrodesulfurized to obtain heavy catalytic cracked gasoline R.
The light catalytic cracking gasoline fraction C total amount obtained in Example 1 and the heavy catalytic cracking gasoline R total amount were mixed to obtain a cracked gasoline base S. Table 5 shows the properties of the cracked gasoline base material S and the related intermediate base material.

  Gasoline base materials obtained by known techniques other than catalytic cracking include desulfurization straight-run naphtha T, catalytic reforming medium oil U, catalytic reforming heavy oil V, alkylate gasoline W, and ethyl t-butyl ether X. The properties are as shown in Table 6. The catalytic reforming medium oil U is obtained by distilling and separating a fraction rich in toluene from catalytic reforming gasoline. The catalytically modified heavy oil V is obtained by distilling and separating aromatics having 9 or more carbon atoms and less than 11 from catalytically modified gasoline.

  Desulfurization straight-run naphtha T is 15% by volume, catalytic reforming medium oil U is 5% by volume, catalytic reforming heavy oil V is 5% by volume, alkylate gasoline W is 5% by volume, and the decomposition described in Example 1 70% by volume of the gasoline base H was blended to prepare an unleaded gasoline composition AA. The properties are shown in Table 7.

  10% by volume of desulfurized straight-run naphtha T, 10% by volume of catalytic reforming medium oil U, 6% by volume of catalytic reforming heavy oil V, 10% by volume of alkylate gasoline W, 7% of ethyl t-butyl ether X The unleaded gasoline composition BB was prepared by blending 57% by volume of the volume% and the cracked gasoline base material H described in Example 1. The properties are shown in Table 7.

  15% by volume of catalytically modified medium oil U, 15% by volume of catalytically modified heavy oil V, 16% by volume of alkylate gasoline W, 7% by volume of ethyl t-butyl ether X, cracked gasoline as described in Example 4 The unleaded gasoline composition CC was prepared by blending 22% by volume of the substrate Q and 25% by volume of the light catalytic cracking gasoline substrate M described in Example 4. The properties are shown in Table 7.

Comparative Example 2

  Desulfurization straight-run naphtha T is 15% by volume, catalytic reforming medium oil U is 5% by volume, catalytic reforming heavy oil V is 5% by volume, alkylate gasoline W is 5% by volume, and the decomposition described in Comparative Example 1 70% by volume of the gasoline base S was blended to prepare an unleaded gasoline composition DD. The properties are shown in Table 7.

Claims (3)

A fractionation step (step A) for fractionating the cracked gasoline fraction to obtain a light cracked gasoline fraction and a heavy cracked gasoline fraction;
A hydrodesulfurization step (step B) for reducing the sulfur content by contacting the heavy cracked gasoline fraction obtained in step A with a catalyst containing molybdenum and / or tungsten in the presence of hydrogen;
All or part of the light cracked gasoline fraction obtained in step A and / or the heavy cracked gasoline fraction with reduced sulfur content obtained in step B contains nickel and zinc in the presence of hydrogen. A collecting and detaching sulfur process (process C) for contacting with a porous desulfurizing agent and reducing the sulfur content to 5 mass ppm or less,
Including a mixing step (step D) of mixing the cracked gasoline fraction obtained by the steps A to C to obtain a low sulfur cracked gasoline base material having a sulfur content of 12 mass ppm or less and a research octane number of 85.0 or more,
The preliminary desulfurization control coefficient α represented by the following formula (1) is 13 to 20 at the stage after the process A and the process B,
α = (LW × LS + HW × HS) / 100 (1)
(Where, LW is the proportion (volume%) of the light cracked gasoline fractionated in step A, LS is the sulfur content (mass ppm) in the light cracked gasoline obtained in step A, and HW is in step A. (The ratio (volume%) of the heavy cracked gasoline fractionated in this manner, and HS represents the sulfur content (mass ppm) in the heavy cracked gasoline obtained in Step B.)
And the ratio of supplying to the process C and treating it with respect to the total amount of cracked gasoline supplied to the process A is 20 vol% or more and 90 vol% or less . Production method. Prior to Step B or Step C, all or part of the cracked gasoline fraction is brought into contact with a catalyst containing at least one metal selected from Group 8 elements in the periodic table in the presence of hydrogen to reduce diene. The method for producing a low-sulfur cracked gasoline base material according to claim 1, further comprising a diene reduction treatment step (step E) in which Before step A, or according to claim 1 or 2, characterized in that it comprises a pretreatment step (step F) to increase the molecular weight of the sulfur compounds contained simultaneously cracked gasoline fraction and the fractional distillation step of step A Manufacturing method of low sulfur decomposition gasoline base material.