JP3730792B2 - Hydrocarbon isomerization process - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for isomerizing hydrocarbons with high efficiency using a sulfuric acid-zirconia solid acid catalyst, and a solid acid catalyst for isomerization used therefor.
[0002]
[Prior art]
The isomerization reaction of hydrocarbons such as petroleum fractions is important as a method for producing a high octane gasoline base material or a chemical raw material. In particular, isomerization of normal butane is an important reaction as a method for producing isobutane as a raw material for methyl-tert-butyl ether and alkylate gasoline, and isomerization of light naphtha is an important reaction as a method for producing a gasoline base material.
[0003]
Conventionally, hydrocarbon isomerization has been performed by bringing a catalyst in which solid oxide properties such as platinum-zeolite and platinum-chlorinated alumina are modified with platinum into contact with the hydrocarbon in the presence of hydrogen. . Platinum-zeolite catalysts are usually reacted using a reaction raw material containing about several tens of ppm of water, and it is known that the catalytic activity is improved even if the amount of water in the reaction raw material is reduced. In general, the catalytic activity is significantly lower than that of platinum-chlorinated alumina. On the other hand, it is known that the activity of platinum-chlorinated alumina catalyst is lowered by impurities such as moisture in the reaction raw material. Usually, the water in the reaction raw material is controlled to 0.5 ppm or less, particularly 0.1 ppm or less. Is reacting. When the water content in the reaction raw material is controlled to 0.5 ppm or less, the platinum-chlorinated alumina catalyst exhibits a much higher catalytic activity than the platinum-zeolite catalyst. However, in an isomerization reaction using a platinum-chlorinated alumina catalyst, it is necessary to continuously introduce an organic chlorine compound into the reaction system in order to maintain the activity of the catalyst, and the chlorine compound is separated from the product after the reaction. I had to remove it. Currently, from the viewpoint of environmental protection including the problem of corrosion in the separation and removal process, the use of such chlorine compounds is in a situation to be avoided.
[0004]
[Problems to be solved by the invention]
Therefore, at present, there is a need for a highly active catalyst that does not require the introduction of a chlorine compound during the hydrocarbon isomerization reaction step. The present invention solves such problems, and provides a method for isomerizing hydrocarbons with high efficiency without using a chlorine compound, and a catalyst used in this method.
[0005]
[Means for Solving the Problems]
As a result of intensive studies by the present inventors, in the case of using a solid acid catalyst containing a support comprising a portion consisting of zirconia and / or hydrous zirconia and a sulfuric acid content supported on the support, It has been found that the catalytic activity is improved by reducing the water content to 5 ppm or less, particularly 1 ppm or less, and that the isomerization reaction of hydrocarbons can be carried out with high efficiency without introducing a chlorine compound into the reaction system. Was completed.
[0006]
That is, in the hydrocarbon isomerization method according to the present invention, the water content of the raw material hydrocarbon is set to 5 ppm or less, particularly 1 ppm or less, and then a support containing a portion composed of zirconia and / or hydrous zirconia is supported on the support. A solid acid catalyst containing sulfuric acid is brought into contact with the raw material hydrocarbon in the presence of hydrogen to obtain an isomerized hydrocarbon. A part in which the solid acid catalyst contains one or more metal components selected from Group 8, Group 9 and Group 10 and / or the support is composed of zirconia and / or hydrous zirconia, and alumina and / or water It is preferable to include a portion made of alumina.
[0007]
In addition, the solid acid catalyst for isomerization according to the present invention is a solid acid catalyst comprising a support containing a portion composed of zirconia and / or hydrous zirconia and a sulfuric acid content supported on the support, and in the presence of hydrogen, It is used for hydrocarbon isomerization to obtain an isomerized hydrocarbon by bringing a raw material hydrocarbon having a moisture weight of 5 ppm or less into contact with the solid acid catalyst.
[0008]
[Operation and effect of the invention]
According to the present invention, hydrocarbon isomerization is carried out by bringing a raw material hydrocarbon containing a water content of 5 ppm or less, particularly 1 ppm or less, into a specific solid acid catalyst in the presence of hydrogen. By using a specific solid acid catalyst, isomerization can be performed with high efficiency without introducing a chlorine compound into the reaction system.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
[Raw material hydrocarbon] As the raw material hydrocarbon to be isomerized in the present invention, light naphtha or hole naphtha obtained by distillation separation of crude oil, butane obtained from a fluid catalytic cracking apparatus, or the like can be used. A hydrocarbon single compound or a mixture of a plurality of compounds having a boiling range of −20 ° C. to 120 ° C., particularly a boiling range of −5 ° C. to 110 ° C. is preferable. Furthermore, these raw material hydrocarbons contain 5 ppm or less, especially 1 ppm or less, more preferably 0.5 ppm or less of moisture as moisture weight. Hydrocarbons containing moisture exceeding this range are used with moisture reduced by an adsorbent or the like.
[0010]
[Isomerization reaction conditions] The isomerization reaction conditions of the present invention vary depending on the catalyst used and the purpose of the reaction, but usually the preferred reaction temperature range is 50 ° C to 250 ° C, particularly 100 ° C to 200 ° C. The reaction pressure ranges from 1 to 50 kgf / cm ² , in particular from 15 to 40 kgf / cm ² , the preferred liquid space velocity LHSV ranges from 0.2 to 10 / hr, and the preferred hydrogen / hydrocarbon feedstock ratio ranges from 0.1 -10 mol / mol.
[0011]
The solid acid catalyst used before the isomerization reaction may be reduced with hydrogen. In this case, the treatment temperature is preferably lower than 300 ° C, and particularly preferably lower than 250 ° C. If the treatment temperature is too high, the sulfuric acid content in the catalyst is reduced and the catalytic activity is lowered. However, these reduction treatments are not essential, and if the reaction is performed in a hydrogen atmosphere, it is not necessary to perform the reduction treatment. Prior to the reduction, the catalyst may be treated with an oxidizing gas such as air.
[0012]
[Impurities in Raw Material Hydrocarbon] In the isomerization method of the present invention, the concentration of water contained in the raw material hydrocarbon is 5 ppm by weight or less, preferably 1 ppm by weight or less, particularly 0.5 ppm by weight. The following is desirable. The moisture contained in the hydrocarbon can be analyzed by a Karl Fischer moisture meter or the like. The concentration of the sulfur compound contained in the hydrocarbon as a raw material is 5 ppm by weight or less in terms of sulfur, preferably 1 ppm by weight or less, and particularly preferably 0.5 ppm by weight or less. The sulfur compound contained in the hydrocarbon can be analyzed by a gas chromatograph equipped with an atomic emission detector (AED). As the concentration of other impurities contained in the hydrocarbon as a raw material, the concentration of the nitrogen compound is 5 ppm by weight or less in terms of nitrogen, preferably 1 ppm by weight or less, particularly 0.1 ppm by weight or less. Is desirable. The concentration of oxygen compound other than water is 5 ppm by weight or less in terms of oxygen, preferably 1 ppm by weight or less, and particularly preferably 0.1 ppm by weight or less. The arsenic compound is preferably 5 ppb or less in terms of arsenic. The lead compound is desirably 20 weight ppb or less in terms of lead. The copper compound is desirably 20 weight ppb or less in terms of copper. The olefin content is 5% by weight or less, preferably 1% by weight or less. The concentration of the chlorine compound is preferably 1 ppm by weight or less, and particularly preferably 0.1 ppm by weight or less, in terms of chlorine.
[0013]
[Impurity in Hydrogen] In the isomerization method of the present invention, as a concentration of the impurity in hydrogen used, a preferable water concentration is 5 ppm by weight or less, particularly 1 ppm by weight or less, and further 0.5 ppm by weight. The following is desirable. The concentration of the sulfur compound is 10 ppm by weight or less in terms of sulfur, preferably 5 ppm by weight or less, and particularly preferably 1 ppm by weight or less. The concentration of the nitrogen compound is 50 ppm by weight or less in terms of nitrogen, preferably 10 ppm by weight or less, and particularly preferably 1 ppm by weight or less. The concentration of oxygen compounds other than water is 500 ppm by weight or less, preferably 100 ppm by weight or less, particularly 50 ppm by weight or less in terms of oxygen.
[0014]
[Solid acid catalyst] As the solid acid catalyst used in the present invention, a solid acid catalyst conventionally known as a sulfuric acid-zirconia system (a carrier containing a part composed of zirconia and / or hydrous zirconia, and a carrier supported on the carrier) Solid acid catalyst containing sulfuric acid component) can be used. In addition, the part which consists of zirconia and / or hydrous zirconia may contain the other metal component in the range in which the effect of this invention is acquired. As other metals, titanium, hafnium, vanadium, chromium, manganese, iron, silicon, tin, gallium, and the like can be used. A composite oxide and / or a hydrous composite oxide may be used, or a single oxide and / or a hydrous oxide portion may be mixed. The part consisting of zirconia and / or hydrous zirconia in the catalyst weight is preferably 20 to 99% by weight, particularly 50 to 99% by weight.
[0015]
The sulfuric acid content in the solid acid catalyst is preferably 0.2 to 10% by weight, particularly 1 to 10% by weight as the amount of sulfur. As the metal component selected from Group 8, Group 9 and Group 10, platinum, palladium, ruthenium, nickel and the like are particularly preferably used, and Group 8, Group 9, and Group 10 in the solid acid catalyst are preferably used. It is preferable to add so that the total amount of group metals may be 0.05 to 10% by weight.
[0016]
The crystal structure of the portion made of zirconia and / or hydrous zirconia of the catalyst used in the present invention is preferably a tetragonal structure. A monoclinic structure may partially exist. This structure can be confirmed by X-ray diffraction. Specifically, the X-ray diffraction peak area ratio of 2θ = 28.2 ° and 2θ = 30.2 ° (hereinafter referred to as S28.2 / S30.2 ratio) by CuKα ray. S28.2 is 2θ = 28. The area of the monoclinic zirconia peak at .2 °, S30.2 is the tetragonal zirconia peak area at 2θ = 30.2 °) is 1.0 or less, preferably 0.3 or less, particularly preferably 0.8. 05 or less. Higher catalytic activity is obtained when there is almost no monoclinic structure.
[0017]
[Preferably used solid acid catalyst] In the isomerization reaction of the present invention, a part composed of zirconia and / or hydrous zirconia (hereinafter also simply referred to as zirconia) and a part composed of alumina and / or hydrous alumina (hereinafter simply referred to as alumina). And a catalyst containing a sulfuric acid component supported on the carrier and a Group 8, 9 or 10 metal component. In this catalyst, aluminum hydroxide and / or hydrated oxide, zirconium hydroxide and / or hydrated oxide, and a compound containing sulfuric acid are kneaded and molded, and the resulting molded product has a tetragonal structure. It is preferably produced by firing at a temperature at which zirconia is obtained, carrying a Group 8, 9 or 10 metal component and then firing at 300 to 700 ° C.
[0018]
In the production of the catalyst to be the subject of the present invention, aluminum hydroxide and / or hydrated oxide can be obtained by various production methods. When α-alumina or γ-alumina, which is an oxide of aluminum, is used instead of aluminum hydroxide and / or hydrated oxide, the crushing strength of the catalyst is reduced, and monoclinic zirconia is formed in the calcining after molding. Is likely to be mixed, and the catalytic activity is reduced.
[0019]
In the aluminum hydroxide and / or hydrated oxide, the weight of alumina in the total weight of alumina and zirconia in the catalyst is 5 to 90% by weight, preferably 5 to 50% by weight, particularly 10 to 50% by weight. It is more preferable. Below this range, the crushing strength of the catalyst decreases and zirconia is difficult to stabilize. When this range is exceeded, the catalytic activity is relatively lowered.
[0020]
The aluminum hydroxide and / or hydrated oxide is usually a powder, preferably having a mean particle size of 0.5 to 50 μm, particularly 0.5 to 20 μm, to improve the activity of the catalyst and the crushing strength. Therefore, it is preferable. As the aluminum hydroxide and / or hydrated oxide, it is preferable to use an aluminum hydrated oxide having a boehmite structure such as pseudoboehmite because the catalytic activity can be improved.
[0021]
Zirconium hydroxide and / or hydrated oxide may be produced in any way, but generally these salts and organometallic compounds such as oxychloride, alcoholate, chloride, sulfate, nitrate, oxy It can be obtained by neutralizing or hydrolyzing sulfate. Zirconium hydroxide or hydrated oxide is amorphous having no clear crystal structure by diffraction of X-rays or electron beams, whereby the crushing strength of the catalyst is improved and zirconia is easily stabilized. Moreover, it is preferable to use a normal powder, preferably a shape having an average particle diameter of 0.5 to 50 μm, particularly 0.5 to 20 μm, in order to improve the activity and crushing strength of the catalyst.
[0022]
Examples of the sulfuric acid-containing compound include sulfuric acid, ammonium sulfate, sulfurous acid, ammonium sulfite, and thionyl chloride. Ammonium sulfate and ammonium sulfite are preferred because the corrosiveness of the production apparatus is low. The sulfuric acid-containing compound may be used as it is or as a solution such as an aqueous solution.
[0023]
The weight of the sulfuric acid-containing compound to be blended during the production of the catalyst is the total weight of the aluminum hydroxide and / or hydrated oxide, zirconium hydroxide and / or hydrated oxide, and the sulfuric acid-containing compound before firing. 3 to 40% by weight, particularly 10 to 30% by weight, is preferable because the catalytic activity can be improved. In particular, ammonium sulfate or the like is preferably used as the solid sulfuric acid-containing compound.
[0024]
Furthermore, the sulfuric acid-containing compound is not particularly limited with respect to the solid state, liquid state, or concentration of the solution, and can be prepared in consideration of the amount of solution necessary for subsequent kneading. The amount of the sulfuric acid-containing compound added is preferably such that the amount of sulfur in the finally obtained solid acid catalyst is 0.2 to 10% by weight, particularly 1 to 10% by weight. The mixing method is not particularly limited.
[0025]
For kneading in catalyst production, any kneader generally used for catalyst preparation may be used, but usually the raw materials are added, water is added and mixed with a stirring blade. However, there is no particular limitation on the order of starting materials and additives. Water is usually added at the time of kneading, but water may not be added when a slurry-like powder is used. The liquid added in addition to water may be an organic solvent such as ethanol, isopropanol, acetone, methyl ethyl ketone, or methyl isobutyl ketone. The kneading temperature and kneading time can be appropriately selected depending on the properties of the raw material aluminum hydroxide and / or hydrated oxide, zirconium hydroxide and / or hydrated oxide, and sulfuric acid-containing compound, There is no particular limitation as long as it does not significantly affect the catalyst performance. Similarly, as long as the catalytic properties of the present invention are maintained, an acid such as nitric acid or a base such as ammonia, an organic compound, a binder, a ceramic fiber, a surfactant, zeolite, or the like may be added and kneaded. I do not care. However, the catalyst of the present invention has sufficient strength and high catalytic activity even without adding such an additive during kneading.
[0026]
For molding after kneading in catalyst preparation, a molding method generally used for catalyst preparation can be used. In particular, extrusion molding using a screw type extruder or the like is preferably used because it can be efficiently molded into an arbitrary shape such as a pellet or honeycomb. Although there is no restriction | limiting in particular in the size of a molded object, Usually, the cross-sectional length is 0.2 mm or more, Preferably it shape | molds to the magnitude | size of 0.5-20 mm. For example, in the case of a cylindrical pellet, one having a diameter of about 0.5 to 10 mm and a length of about 0.5 to 15 mm can be easily obtained. Since the crushing strength after firing is greatly affected by kneading, it is desirable to determine in advance the moisture, kneading time, electric energy, etc. during the kneading.
[0027]
Since steps such as filtration and drying are not included between mixing / kneading and molding of the sulfuric acid-containing compound, the operation is simple, and there is a great industrial advantage. Further, since a molded catalyst can be obtained, it can also be applied to a fixed bed reaction, which was difficult with a conventional powder catalyst.
[0028]
Firing after molding is performed at a temperature at which tetragonal zirconium oxide is obtained in a gas atmosphere such as air or nitrogen. When pseudoboehmite type alumina is used, a preferable baking temperature is 450 to 800 ° C., particularly 500 to 800 ° C., further 600 to 800 ° C., and a preferable baking time is 0.1 to 20 hours. If the calcination temperature is too high, the proportion of monoclinic crystals in the zirconium oxide crystal structure increases, and the peak area ratio of 2θ = 28.2 ° and 30.2 ° may exceed 1, and the catalytic activity also decreases. Therefore, it is not preferable. On the other hand, if the calcination temperature is too low, the zirconium oxide is not crystallized and the catalytic activity is also lowered, which is not preferable.
[0029]
In particular, platinum, palladium, ruthenium, nickel and the like are suitably used as the metal component selected from Group 8, Group 9 and Group 10 contained in the catalyst used in the present invention. These are preferably used in the form of a compound rather than the metal itself. These metal compounds can be used both as anhydrides and as hydrates. Furthermore, these metal compounds may be used alone or as a mixture of two or more. The addition amount of these metal compounds should be such that the total amount of Group 8, 9 and 10 elements in the finally obtained solid acid catalyst is 0.05 to 10% by weight. Is preferred.
[0030]
There are no particular restrictions on the loading method, but an impregnation method such as spraying or dipping, an ion exchange method, or the like is preferably used. In order to increase the activity of the catalyst, the support is preferably calcined at a temperature higher than 300 ° C. and lower than 700 ° C. for 0.1 to 20 hours in a gas atmosphere such as air or nitrogen.
[0031]
The total amount of zirconia and alumina in the catalyst according to the present invention is preferably 70% by weight or more, more preferably 80% by weight or more from the viewpoints of catalyst activity and strength of the molded product. The molding strength of the catalyst is preferably 3 kg or more as a side crushing strength of a cylindrical pellet having a diameter of 1.5 mm.
[0032]
【Example】
Hereinafter, the embodiment will be described in detail.
[0033]
[Calculation method of crystal seed ratio by X-ray diffraction]
Separation of tetragonal and monoclinic peaks of zirconia from the X-ray diffraction chart, and the peak area of monoclinic zirconia at 2θ = 28.2 ° and the peak area of tetragonal zirconia at 2θ = 30.2 ° The ratio (S28.2 / S30.2 ratio) was calculated. When the S28.2 / S30.2 ratio was 0.02 or less, the monoclinic peak was unclear and could not be detected. The X-ray diffraction chart was measured using a wide-angle X-ray measurement apparatus (RAD-1C, Rigaku Denki Co., Ltd., wavelength 1.5406 mm).
[0034]
[Measurement method of average particle diameter]
Measurement was performed by a wet measurement method using a Nikkiso Co., Ltd. MICROTRAC particle size analyzer. In this method, a flowing powder group is irradiated with laser light, and particle size analysis is performed using the forward scattered light.
[0035]
[Method for preparing solid acid catalyst]
Commercially available zirconium hydroxide was dried to obtain dry hydrated zirconia having an average particle size of 1.2 μm. To 1.50 kg of this dried hydrated zirconia powder, 500 g of hydrated alumina (pseudo boehmite powder) having an average particle size of 10 μm is added, and 383 g of ammonium sulfate is further added. It was. The obtained kneaded material was extruded from an extruder having a circular opening (diameter 1.6 mm) and dried at 110 ° C. to obtain dry pellets. Subsequently, the dried pellet was fired at 650 ° C. for 2 hours to obtain a zirconia shaped body carrying a sulfuric acid content. To 50 g of this zirconia shaped body, 125 ml of an aqueous solution of chloroplatinic acid was added so that the amount of platinum in the catalyst was 0.5%. This was dried and then calcined at 500 ° C. for 2 hours to obtain a solid acid catalyst which is a catalyst of a zirconia / alumina molded body supporting platinum and sulfuric acid.
[0036]
[Reaction Raw Material] Light naphtha was used as a hydrocarbon as a raw material for isomerization. This light naphtha contains 4.9% by weight of butane, 56.3% by weight of pentane, 32.6% by weight of hexane, 2.3% by weight of cyclopentane, 2.8% by weight of methylcyclopentane and cyclohexane, It contained 1.1% by weight of benzene, 0.1% by weight of olefin, 40% by weight of water, and the sulfur content was 1 ppm by weight or less. This light naphtha is used as the reaction raw material 1. In addition, the reaction raw materials in which the water in the light naphtha is dehydrated with molecular sieve 3A to have the water content of 20 ppm by weight, 0.9 ppm by weight, and 0.4 ppm by weight are respectively prepared as reaction raw material 2, reaction raw material 3, and reaction raw material. Prepared as 4. As other impurities contained in the reaction raw materials 2 to 4, the concentration of the sulfur compound is 1 ppm by weight or less in terms of sulfur, the concentration of the nitrogen compound is 0.1 ppm by weight or less in terms of nitrogen, and the concentration of oxygen compounds other than water is in terms of oxygen 0.1 ppm by weight or less, arsenic compounds are 5 ppb or less in terms of arsenic, lead compounds are 20 ppb or less in terms of lead, copper compounds are 20 ppb or less in terms of copper, and the concentration of chlorine compounds is 0 in terms of chlorine .1 ppm by weight or less.
The hydrogen gas used in the reaction has a purity of 99.99% by volume and water content of 0.5 ppm by weight or less. As other impurities, the concentration of sulfur compound is 1 ppm by weight or less in terms of sulfur, and the concentration of nitrogen compound. Was 0.1 weight ppm or less in terms of nitrogen, the concentration of oxygen compounds other than water was 0.1 weight ppm or less in terms of oxygen, and the concentration of chlorine compounds was 0.1 weight ppm or less in terms of chlorine.
[0037]
[Reaction Method] The solid acid catalyst was sized into 16 to 24 mesh particles. After the sizing, 4 ml of the catalyst was packed into a fixed bed flow reactor having a length of 50 cm and an inner diameter of 1 cm, and an isomerization reaction was performed after pretreatment. The catalyst was pretreated at 200 ° C. in a normal pressure hydrogen stream.
[0038]
The isomerization reaction of hydrocarbons was carried out under the conditions of a reaction pressure (gauge pressure) of 30 kg / cm ² , LHSV 2 h ⁻¹ , a hydrogen / hydrocarbon ratio of 2 (mol / mol) and a reaction temperature of 150 ° C. As raw materials, reaction raw materials 1 to 4 were used to start the reaction, and the outlet gas of the reactor 200 hours after the start of the reaction was analyzed by gas chromatography. The reaction tube outlet composition, which is the analysis result, is shown in Table 1. It can be seen that the catalytic activity is greatly improved when the weight of water in the raw material is 1 ppm or less.
[0039]
[Table 1]

Claims (4)

After the water content of the hydrocarbon feedstock and 5ppm or less, the carrier comprising a portion consisting of zirconia and / or hydrated zirconia, a solid acid catalyst containing a sulfureous component supported on this support, the presence of hydrogen, the feedstock A hydrocarbon isomerization method for obtaining an isomerized hydrocarbon by contacting with a hydrocarbon.   The hydrocarbon isomerization method according to claim 1, wherein the carrier of claim 1 comprises a portion comprising zirconia and / or hydrous zirconia and a portion comprising alumina and / or hydrous alumina.   The hydrocarbon isomerization method according to claim 1 or 2, wherein the solid acid catalyst according to claim 1 contains one or more metal components selected from Group 8, Group 9, and Group 10. A solid acid catalyst comprising a support comprising a portion composed of zirconia and / or hydrous zirconia and a sulfuric acid content supported on the support, wherein the raw material hydrocarbon having a water weight of 5 ppm or less in the presence of hydrogen is the solid A solid acid catalyst for isomerization, which is used for isomerization of a hydrocarbon to obtain an isomerized hydrocarbon by contacting with an acid catalyst.