JP4776984B2 - Method for producing low sulfur light hydrocarbon oil - Google Patents

Description

  The present invention provides a low sulfur light carbonization by treating a light hydrocarbon oil mainly containing a hydrocarbon having 3 to 10 carbon atoms, particularly 3 to 4 carbon atoms containing a sulfur compound, with an adsorbent. The present invention relates to a method for producing hydrogen oil.

Dealing with environmental problems is a major issue in the 21st century automobile and its fuel, and it is a fuel oil from the viewpoint of both CO ₂ emission reduction, which is a global warming gas, and so-called automobile emission reduction such as NOx. There is an increasing demand for reducing the sulfur content of hydrocarbon oils.

  Conventionally, the hydrodesulfurization method, which is a hydrocarbon oil desulfurization technique that has been used mainly, is used as it is, and further removal of trace amounts of sulfur compounds remaining in fuel oil is a reaction at higher temperature and pressure than before. Therefore, energy consumption is large, and the cost is greatly increased due to a huge amount of catalyst and hydrogen consumption. In particular, in the case of a hydrocarbon having a low boiling point such as LPG (liquefied petroleum gas), it is necessary to cool and liquefy again after heating to high temperature, vaporizing and desulfurization, and the energy consumption is also large.

  For example, LPG is transported through piping in refineries, usually in a liquid phase. However, as the desulfurization, a method of once vaporizing, hydrodesulfurizing in a gas phase, and then liquefying again is taken, and a great deal of energy is required for vaporization and liquefaction. In particular, for LPG stored as a liquid by cooling near normal pressure, a large energy loss has been a problem in desulfurization.

  As a desulfurization method for hydrocarbon oil with low energy consumption, a desulfurization method by adsorption is known. Since this method can be desulfurized under mild conditions without using hydrogen, it can be carried out with simple facilities and low operating costs, and has the advantage of low energy consumption. Although a method for desulfurization of LPG with an adsorbent is also known, it is generally necessary to heat to a temperature of 100 ° C. or higher, and in order to process LPG with a high vapor pressure, equipment that can withstand extremely high pressure is required. It was. In addition, a vapor phase desulfurization method using an LPG adsorbent near normal temperature is also known, but it is once vaporized and liquefied again after desulfurization, which requires a lot of energy.

On the other hand, hydrocarbon oils produced in the intermediate process of petroleum refining include hydrocarbon oils containing a high concentration of sulfur and containing a plurality of types of sulfur compounds and hydrocarbon compounds, depending on the raw materials and manufacturing processes. Such hydrocarbon oils were consumed exclusively in private refinery fuels for reasons such as the high cost of the desulfurization process and the high reactivity of the contained compounds, and were not effectively utilized as commercial products. . Examples of such a fraction include hydrocarbon oil obtained by treating a fraction obtained from a heavy oil pyrolysis apparatus for petroleum refining. This fraction has a high sulfur concentration and varies greatly. Moreover, as a sulfur compound, disulfides are included as a main component and many other types of sulfur compounds are included. Furthermore, this fraction contains nitrogen compounds and the like. In addition, the hydrocarbon compounds also include many types of paraffins and olefins.

  Although methods for adsorbing the sulfur content of hydrocarbon oil in a liquid phase state are known (see, for example, Patent Documents 1 to 4), these methods are special in that the main component of the sulfur compound is a disulfide. It is not intended for desulfurization of hydrocarbon oils.

In addition, conventionally, a method for adsorptive desulfurization of hydrocarbon oils containing disulfides and various other compounds as sulfur compounds such as the above-mentioned pyrolysis oil and varying in concentration, particularly in a liquid phase state near normal temperature There has been no proposal of a method capable of proper desulfurization.
JP 2001-205004 A Japanese Patent Publication No. 38-26866 Japanese Patent No. 2938096 Japanese Patent Laid-Open No. 03-103493

  The present invention solves such a problem in the prior art, and even a hydrocarbon oil containing disulfides does not consume hydrogen, consumes less energy, and reduces the burden on the environment. It is an object to provide a method for producing a low sulfur light hydrocarbon oil by desulfurizing a light hydrocarbon oil.

  The present inventors have found that a sulfur component mainly composed of disulfides contained in hydrocarbon oil can be efficiently desulfurized by an adsorbent even in a liquid phase state at around room temperature, and have arrived at the present invention.

That is, the present invention treats a light hydrocarbon oil containing disulfides and having a concentration of 4 or more carbon atoms having a carbon number of 4 or more with an adsorbent, whereby the sulfur content of the hydrocarbon oil is 10 ppm or less, Preferably, it is a method for producing a low-sulfur light hydrocarbon oil that removes even 5 ppm or less, more preferably 2 ppm or less, and particularly 1 ppm or less.
In the method for producing a low sulfur light hydrocarbon oil according to the present invention, the light hydrocarbon oil is preferably a hydrocarbon oil obtained from a heavy oil pyrolysis apparatus. In addition, the light hydrocarbon oil that has a diene as the hydrocarbon compound can achieve the effect of the present invention more remarkably. Furthermore, the adsorbent is preferably a faujasite type zeolite. Further, it is preferable that light hydrocarbons are directly passed through the adsorbent without pretreatment when passing through the adsorbent.

  In the present invention, it is possible to efficiently adsorb and desulfurize a sulfur compound of disulfides contained in a hydrocarbon oil in a liquid phase at around room temperature by bringing it into contact with a specific adsorbent. For this reason, light hydrocarbon oil can be efficiently desulfurized by a method that consumes less energy and reduces the burden on the environment without heating the hydrocarbon oil or consuming hydrogen. .

In the method for producing a low sulfur light hydrocarbon oil according to the present invention, the hydrocarbon oil to be desulfurized contains disulfides as the main component of the sulfur compound and contains at least mercaptans as the other sulfur compounds, but has 4 carbon atoms. Any hydrocarbon oil can be suitably used as long as it is a light hydrocarbon oil having a mercaptan content of 10 ppm or less.
Light hydrocarbon oils that can be suitably applied are specifically LPG fractions and light gasoline fractions, and are mainly composed of hydrocarbons having 3 to 10 carbon atoms. The LPG fraction is a fuel gas and an industrial raw material gas mainly composed of propane, propylene, butane, butylene, butadiene and the like. Usually, it is stored in a spherical tank in a liquid phase under normal pressure and pressure, or is stored in a liquid phase at a low temperature in a state close to atmospheric pressure.
A light gasoline fraction is a base material corresponding to a gasoline fraction or a naphtha fraction produced in a so-called refinery. In general, gasoline is mainly composed of hydrocarbons having about 3 to 11 carbon atoms, the density (15 ° C.) is 0.783 g / cm ³ or less, and the boiling point range is about 30 to 220 ° C. Moreover, a light gasoline fraction and a naphtha fraction having about 3 to 7 carbon atoms may be used.

  Moreover, the component composition of the hydrocarbon compound of the hydrocarbon oil which is the target of the adsorptive desulfurization method used in the present invention is not particularly limited. As the hydrocarbon compound, in addition to paraffins, olefins and more reactive dienes may be included. According to this method, even in a hydrocarbon oil containing a more reactive diene, the occurrence of a differential pressure between the adsorption tank inlet and the outlet is not observed during the adsorption operation because the polymerization of the diene does not proceed. The diene content is not particularly limited, but is generally several weight percent or less, preferably 2 weight percent or less. Dienes are hydrocarbon compounds containing two double bonds, such as 1,3-butadiene, 1,2-pentadiene, 1,3-pentadiene (cis, trans), 1,4-pentadiene, 2- Examples include methyl-1,3-butadiene, cyclopentadiene, 1,4-hexadiene (cis, trans), 1,5-hexadiene, and cyclohexadiene.

  The sulfur concentration of the hydrocarbon oil used in the production method of the present invention is not particularly limited as long as it contains disulfides and the content of mercaptans having 4 or more carbon atoms is 10 ppm or less. For example, a hydrocarbon oil having a sulfur concentration of 10 to 5000 ppm, preferably 10 to 1000 ppm can be mentioned. The lower the sulfur concentration of the hydrocarbon oil, the longer the life of the adsorbent, and the better the desulfurization economy.

  The sulfur compound contained in the light hydrocarbon oil is preferably disulfides with 50% or more, particularly 80% or more, of the sulfur concentration. It is preferable that 0.1 ppm or more of mercaptans is contained as another sulfur compound. In addition, thiophenes, sulfides and the like may be included. However, mercaptans are highly reactive and easily form disulfides. Accordingly, since mercaptans having a large molecular weight (4 or more carbon atoms) form disulfides having a large molecular weight and low adsorption characteristics, the content of mercaptans (4 or more carbon atoms) is set to 10 ppm or less. In addition, other sulfur compounds having a large molecular weight also have a content of 10 ppm or less because the life of the adsorbent is shortened. Examples of other sulfur compounds having a large molecular weight include disulfides having 5 or more carbon atoms, sulfides having 5 or more carbon atoms, thiophenes, and benzothiophenes.

Examples of light hydrocarbon oils that contain a relatively large amount of disulfide sulfur compounds include, for example, LPG fractions obtained from heavy oil pyrolysis equipment in petroleum refining and hydrocarbons having 3 to 10 carbon atoms as the main component. Light gasoline fraction. These may be a fraction obtained by reducing the sulfur content by hydrodesulfurization or a fraction obtained by reducing mercaptans by soda washing or the like, and can be preferably used in the present invention. A thermal cracking device is a device that decomposes heavy hydrocarbon oil at high temperature to obtain light hydrocarbon oil without using a catalyst. In petroleum refining, for example, heavy hydrocarbon oils such as atmospheric distillation residues, mainly vacuum distillation residues, are pyrolyzed and converted into light hydrocarbon oils such as kerosene, light oil, and gasoline fractions. Used for effective use. Processes include coking processes that convert residues into light oil and coke (typical processes include delayed coking equipment and flexi coking equipment), visspraying processes that reduce residue viscosity, and residues into light oil. The Yurika system and HSC process are known.

  As for the treatment for reducing mercaptans, there are a method of removing sulfur from mercaptans and a method of converting mercaptans to another substance other than mercaptans to make them heavy. Extraction described in Petrotech 17 (11), 974 (1994) and Kodansha Scientific “Petroleum Refining Process” (1998), known as sweetening of petroleum fractions, is a method for removing sulfur by mercaptans. Examples include a type sweetening process, an extraction oxidation type sweetening process, and a method employing a known method. Alternatively, a method of contacting a fraction with a desulfurizing agent having a sulfur compound adsorption or sorption function may also be mentioned. Moreover, the method of isolate | separating mercaptans with a large molecular weight and a high boiling point by distillation operation is also mentioned.

  In addition, disulfides, which are the main component of sulfur compounds, are disulfides. It is a general term for alkyl disulfide and aryl disulfide, and is a sulfur compound represented by the general formula R—S—S—R ′ (R and R ′ are hydrocarbon groups such as alkyl groups). The sum of the carbon number of the hydrocarbon group constituting R and R ′ is preferably 2 to 8, specifically, dimethyl disulfide, methyl ethyl disulfide, methyl propyl disulfide, diethyl disulfide, methyl butyl disulfide, ethyl propyl disulfide, Examples thereof include chain disulfides such as methylpentyl disulfide, ethylbutyl disulfide, dipropyl disulfide, methylhexyl disulfide, ethylpentyl disulfide, propylbutyl disulfide, methylheptyl disulfide, ethylhexyl disulfide, propylpentyl disulfide, and dibutyl disulfide.

  Mercaptans are sulfur compounds having a mercapto group (—SH), and are represented by the general formula RSH (where R is a hydrocarbon group such as an alkyl group or an aryl group). Mercaptans are also called thiols or thioalcohols. Mercapto groups are highly reactive and react particularly easily with metals. Typical mercaptans include methyl mercaptan, ethyl mercaptan, propyl mercaptan (including isomers), butyl mercaptan (including isomers such as tertiary butyl mercaptan), pentyl mercaptan, hexyl mercaptan, heptyl mercaptan, octyl mercaptan, nonyl Examples include mercaptans, decyl mercaptans, and thiophenols Ar-SH (Ar is an aryl group).

Sulfides, also called thioethers, are a generic term for alkyl sulfides and aryl sulfides, and are sulfur compounds represented by the general formula R—S—R ′ (R and R ′ are hydrocarbon groups such as alkyl groups and aryl groups). is there. This is a compound in which two hydrogen atoms of hydrogen sulfide are substituted with an alkyl group or the like. Sulfides are classified into chain sulfides and cyclic sulfides. The chain sulfides are sulfur compounds having no heterocyclic ring containing a sulfur atom as a different atom, and derivatives thereof. Typical chain sulfides include dimethyl sulfide, methyl ethyl sulfide, methyl propyl sulfide, diethyl sulfide, methyl butyl sulfide, ethyl propyl sulfide, methyl pentyl sulfide, ethyl butyl sulfide, dipropyl sulfide, methyl hexyl sulfide, ethyl pentyl sulfide. Propyl butyl sulfide, methyl heptyl sulfide, ethyl hexyl sulfide, propyl pentyl sulfide, dibutyl sulfide and the like. Cyclic sulfides have a heterocyclic ring containing at least one sulfur atom as a heteroatom among the sulfides and have no aromaticity (a penta- or hexa-atom ring and two or more double bonds). It is a sulfur compound that does not have a heterocyclic ring. Typical cyclic sulfides include tetrahydrothiophene (tetramethylene sulfide, molecular formula C ₄ H ₈ S, molecular weight 88.1), methyltetrathiophene, and the like.

Thiophenes are heterocyclic compounds containing one or more sulfur atoms as heteroatoms, and the heterocycle is a penta- or hexa-atom ring and has aromaticity (has two or more double bonds in the heterocycle). And a sulfur compound in which a heterocyclic ring is not condensed with a benzene ring and derivatives thereof. Also included are compounds in which heterocycles are fused together. Thiophene, also called thiofuran, is a sulfur compound having a molecular weight of 84.1 and represented by the molecular formula C ₄ H ₄ S. Other representative thiophenes include methylthiophene, dimethylthiophene, trimethylthiophene, ethylthiophene, propylthiophene, butylthiophene, pentylthiophene, and the like.

Benzothiophenes are heterocyclic compounds containing one or more sulfur atoms as heteroatoms, and the heterocycle is a penta- or hexa-atom ring and has aromaticity (two or more double bonds in the heterocycle). And a sulfur compound in which a heterocyclic ring is condensed with one benzene ring. Benzothiophene, also called thionaphthene or thiocoumarone, is a sulfur compound having a molecular weight of 134.2, which can be represented by the molecular formula C ₈ H ₆ S. Other typical benzothiophenes include methylbenzothiophene, dimethylbenzothiophene, trimethylbenzothiophene, tetramethylbenzothiophene, pentamethylbenzothiophene, hexamethylbenzothiophene, methylethylbenzothiophene, dimethylethylbenzothiophene, trimethylethylbenzo Thiophene, tetramethylethylbenzothiophene, pentamethylethylbenzothiophene, methyldiethylbenzothiophene, dimethyldiethylbenzothiophene, trimethyldiethylbenzothiophene, tetramethyldiethylbenzothiophene, methylpropylbenzothiophene, dimethylpropylbenzothiophene, trimethylpropylbenzothiophene, Tetramethylpropylbenzothiophene, pentame Le propyl benzothiophene, methyl ethyl propyl benzothiophene, dimethyl ethyl propyl benzothiophene, trimethyl ethylpropyl benzothiophene, alkyl benzothiophenes such as tetramethyl-ethylpropyl benzothiophene and the like

The adsorbent used in the present invention may be any adsorbent that has an adsorption ability for low molecular weight disulfides, mercaptans, sulfides, thiophenes, and the like. For example, the adsorbent preferably used in the present invention is an adsorbent mainly composed of faujasite type zeolite. The content of the faujasite-type zeolite is 60% by weight or more, particularly 70% by weight or more, and is substantially free of components other than the faujasite-type zeolite. The impurity content is preferably 5% by weight or less, particularly preferably 1% by weight or less. As the faujasite type zeolite, it is preferable to use NaX type or NaY type. In the faujasite type zeolite (FAU), the structural unit of the skeleton structure is a 4-membered ring, a 6-membered ring and a 6-membered double ring. The micropores have a three-dimensional structure, the entrance is a circle formed by a non-planar 12-membered ring, and the crystal system is cubic. The faujasite stone, which is a faujasite type natural zeolite, is represented by the molecular formula (Na ₂ , Ca, Mg) ₂₉ .Al ₅₈ Si ₁₃₄ O ₃₈₄ .240H ₂ O and the like, and the micropore diameter is 7.4 × 7. The size of the unit cell is 24.74 cm. As faujasite type synthetic zeolite, there are X type and Y type. NaX type zeolite is represented by Na ₈₈ [(AlO ₂ ) ₈₈ (SiO ₂ ) ₁₀₄ ] · 220H ₂ O and can adsorb molecules having an effective diameter of about 10 mm. NaY-type zeolite can adsorb molecules having an effective diameter of up to about 8 mm. The faujasite type zeolite preferably used in the present invention is represented by the general formula: xNa ₂ O.Al ₂ O ₃ .ySiO ₂ , and X <1 and y <10 are preferably used. The SiO ₂ / Al ₂ O ₃ molar ratio is preferably 10 mol / mol or less.

The adsorption of the raw material hydrocarbon oil can be performed by a known adsorption operation. For example, adsorption by a fixed layer (method of removing hydrocarbon oil after immersing the adsorbent in hydrocarbon oil for a certain period of time, method of contacting with the fixed layer of adsorbent under the passage of hydrocarbon oil), moving bed, Adsorption by a fluidized bed or adsorption by a simulated moving bed can be performed. By adjusting the adsorption conditions such as the amount of hydrocarbon oil, the amount of adsorbent, the oil feed rate of the hydrocarbon oil, the contact time with the adsorbent, and the temperature, the hydrocarbon oil adsorbed and desulfurized according to the present invention has a sulfur concentration. 10 ppm or less, preferably 5 ppm or less, further 2 ppm or less, 1 ppm or less. Also, the nitrogen concentration can be 1 ppm or less. Usually, the adsorption temperature is 60 ° C. or less, and in particular, since the adsorption capacity of the adsorbent can be increased, it is preferable to perform the treatment at a lower temperature. For economic reasons, excessively low temperatures should be avoided, and near room temperature is more preferred. The contact with the adsorbent is preferably performed in a liquid phase, but may be performed in a gas phase.
As the adsorbent, a highly active one that does not adsorb moisture or the like is used. However, at the start of oil passing, pretreatment of the adsorbing tank filled with the adsorbing agent such as passing a mixed gas of nitrogen and low sulfur LPG gas is performed before starting the oil passing in order to prevent heat generation of the adsorbent. In addition, it is desirable that the light hydrocarbon oil is directly passed through the adsorbent layer because the life can be extended.

  Light fractions obtained by treating the fractions obtained from petroleum refining as described above are further refined as necessary, so that household and industrial fuels, automotive fuels, raw materials for petrochemical processes, etc. Can be used as Examples of petrochemical processes include olefin production processes and cyclization processes. An example of a cyclization process, which is a petrochemical process for aromatizing hydrocarbon oil, is a cycler (Licensor: BP / UOP) made mainly of LPG (paraffin having 3 to 4 carbon atoms), Alpha (α) (Licensor: Asahi Kasei / Sanyo Petrochemical) using olefins with 3 to 8 carbon atoms and paraffin as raw materials, Z Forming (Licensor: Nippon Oil / Chiyoda) using LPG light naphtha as raw materials Chemical). As a catalyst for these processes, ZSM-5 (metallosilicate) carrying or modifying Ga or Zn is used (“Aromatics”, Vol. 49, No. 5, 6 (1997), “Petrotech”, Vol. 27. No. 12 (2004)).

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

A cracked light fraction obtained by treating a crude oil vacuum distillation residue from a delayed coker apparatus is fractionated by a splitter to obtain an LPG fraction, which is further washed with soda to obtain an LPG fraction having a length of 0. .9m, inner volume 7L adsorbent layer, pressure 0.5MPaG, temperature 10-20 ° C, linear velocity 0.7m / hr (residence time: 1.3 hours) in liquid phase length Oiled in the direction. As an adsorbent, a molded faujasite type zeolite NaX type (Zeoram F-9 9-14 # manufactured by Tosoh Corporation) was used. The adsorber filled with the adsorbent in advance is 45 minutes at 45 L / min with a low sulfur concentration 3 hydrocarbon gas (20 vol%) and nitrogen (80 vol%) mixed gas (sulfur content 2ppm). Thereafter, the LPG fraction was passed through oil at 20 L / min for 45 minutes, and then an evaluation test was performed. Table 1 shows the composition, sulfur concentration, and nitrogen concentration of the LPG fraction. The sulfur content was measured according to ASTM D5453, the nitrogen content was measured according to JIS K2609, and the hydrocarbon composition was measured according to JIS K2240.
Each concentration of sulfur, nitrogen, paraffins, olefins, and the like fluctuates due to changes in the raw material of the delayed coker apparatus. Regarding the sulfur compound, mercaptans having 4 or more carbon atoms, disulfides having 5 or more carbon atoms, sulfides having 5 or more carbon atoms, and thiophenes were not substantially contained and were below the lower limit of detection. The sulfur content of each sulfur compound was measured by gas chromatography with a chemiluminescence detector.

  The change in sulfur concentration in the LPG fraction at the column outlet after the start of oil passing is shown in FIG. It can be seen that the sulfur concentration gradually increases from around 35 hours. It can be seen from this figure that the sulfur concentration at the outlet is 10 ppm or less until 4 to 42 hours at the beginning of oil passage, 2 ppm or less until 10 to 34 hours, and 1 ppm for 16 to 20 hours, regardless of large fluctuations in the sulfur concentration at the inlet. Was less than. The nitrogen concentration was 1 ppm or less from the start to the end of oil passing. Further, no increase in the differential pressure before and after the column due to polymerization of dienes was observed. There was no significant change in the composition of olefins before and after the adsorption treatment. Note that sulfur and nitrogen can be desulfurized to a lower concentration by making the adsorbent layer longer.

Comparative Example 1

To light hydrocarbon oil containing normal decane 55 wt%, 1-hexene 44 wt%, and 1,3-pentadiene 0.4 wt%, dimethyl disulfide, normal butanethiol, dimethyl sulfide, propionitrile were added, and the sulfur concentration and nitrogen The concentration was adjusted. The total sulfur concentration was 356 ppm, the concentration of each sulfur compound was 322 ppm dimethyl disulfide, 26 ppm normal butanethiol, 8 ppm dimethyl sulfide, and the nitrogen concentration was 4 ppm.
The light hydrocarbon oil thus prepared was adsorbed in a layer of 0.3 m in length and filled in an internal volume of 26 mL at a pressure of 0.25 MPaG, 25 ° C., a linear velocity of 0.7 m / hour (residence time). : 25 minutes) in the liquid phase state, oil was passed in the length direction.
As the adsorbent, molded faujasite type zeolite NaX type (synthetic zeolite, F-9, granular (Wako Pure Chemical Industries, Ltd.)) was used.
FIG. 2 shows changes in sulfur concentration in the hydrocarbon oil at the column outlet after the start of oil passing. Around 12 hours, the sulfur concentration at the outlet exceeded 10 ppm. The main sulfur compounds at the outlet at that time are methyl normal butyl disulfide, dinormal butyl disulfide and the like, and these compounds are considered to be compounds reacted with normal butane thiol. Further, the time when dimethyl disulfide (DMDS) alone exceeds 10 ppm is after about 16 hours. Therefore, it can be seen that the time for the sulfur concentration at the outlet to reach 10 ppm is shortened by containing heavy normal butanethiol. In addition, the nitrogen concentration was 1 ppm or less within this oil passing time.

In the same manner as in Example 1, an adsorbent layer having a length of 0.9 m and an internal volume of 7 L was subjected to a pressure of 0.5 MPaG, a temperature of 10 to 20 ° C., and a linear velocity of 0.7 m / hour (residence time: 1.3). ) In the liquid phase state in the length direction. As an adsorbent, a molded faujasite type zeolite NaX type (Zeoram F-9 9-14 # manufactured by Tosoh Corporation) was used. In addition, the adsorption tank previously filled with the adsorbent was not processed.
The adsorption capacity obtained from the time when the outlet concentration / inlet concentration = 50% and the average sulfur concentration was 33 gS / kg-ads (ads indicates the adsorbent). On the other hand, in Example 1, it was 24 gS / kg-ads. From the above, the lifetime of the adsorbent can be extended by directly passing the LPG fraction in the liquid phase without performing the initial treatment.

The change of the sulfur concentration in the hydrocarbon oil in the column exit in Example 1 is shown. The change of the sulfur concentration in the hydrocarbon oil in the column exit in the comparative example 1 is shown.

Claims (2)

An LPG fraction obtained from a heavy oil pyrolyzer containing dienes and disulfides and having a carbon number of 4 or more and a mercaptan concentration of 10 ppm or less is converted into a liquid phase using a faujasite type zeolite NaX type adsorbent. A method for producing a low-sulfur light hydrocarbon oil, characterized in that the sulfur content of the LPG fraction is removed to 10 ppm or less by treating with the above. The method for producing a low sulfur light hydrocarbon oil according to claim 1, wherein the sulfur content of the LPG fraction is removed to 1 ppm or less.

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