JPH0639399B2 - Partial hydrogenation method for monocyclic aromatic hydrocarbons - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for partially hydrogenating a monocyclic aromatic hydrocarbon to produce corresponding cycloolefins, particularly cyclohexenes.

Cyclohexenes are highly valuable as intermediate raw materials for organic chemical industrial products, and are especially important as polyamide raw materials and lysine raw materials.

(Prior Art) Many proposals have been made as methods for producing such cyclohexenes. For example, (1) a method using a catalyst composition containing water and an alkali agent and a Group VIII element of the periodic table (Japanese Patent Publication No. 56-22850), (2) a ruthenium catalyst containing copper, silver, cobalt or potassium. With water and water and a phosphate compound (Japanese Patent Publication No. 56-45)
36), (3) ruthenium catalyst and I of the periodic table
A method of reacting in the presence of a neutral or acidic aqueous solution containing a salt of at least one cation selected from Group A metals, Group IIA metals, manganese, zinc and ammonia (Japanese Patent Laid-Open No. Sho 5).
0-142536).

(Problems to be Solved by the Invention) However, in these conventionally known methods, there are problems such as low selectivity and yield of the target cyclohexenes, and extremely low reaction rate, which are in practical use. And on the other hand, the selection of the material of the reactor, that is,
There is almost no study on the influence of the material of the reactor or the like on the reaction, and it is the current situation that no study has been made on what kind of material is industrially preferable to use. For example, in Japanese Examined Patent Publication No. 56-22850, for example, in partial hydrogenation with a monocyclic aromatic hydrocarbon, a reactor having a wetted portion coated with a fluorine-based resin is used to influence the material. Although the reaction is carried out in an environment that can ignore, generally, in coating with a fluorine-based resin, the atmosphere in which it is used, for example, temperature, pressure, etc. are naturally limited, and even within the limits, for a long time. The durability, especially the peeling resistance, is very open to doubt, and it is difficult to say that it is an appropriate material for carrying out the reaction industrially.

On the other hand, according to the studies by the present inventors, particles mainly composed of metal ruthenium, for example, those having an average crystallite size of metal ruthenium of 200 Å or less, or ruthenium containing a zinc compound or an iron compound in advance. The invention has been made in which cycloolefins can be obtained with a remarkably high selectivity and yield when used in the presence of water using a reduced product or the like as a hydrogenation catalyst. Then, austenitic stainless steels (for example, SUS-304, SUS-31) commonly used in the reaction or a hydrogenation reaction similar to the reaction.
6) etc., it becomes clear that the performance of the catalyst, that is, the selectivity and the yield of cycloolefins, is considerably reduced. It has been found that selecting the material is extremely important.

(Means for Solving Problems) In order to solve such problems, the inventors of the present invention have earnestly studied a reactor material that can exert the performance of the catalyst in any way and is also industrially and economically preferable. That is, the present invention has been achieved.

That is, by using particles of monocyclic aromatic hydrocarbons mainly composed of metal ruthenium as a hydrogenation catalyst, in the coexistence of water, when partially hydrogenating with hydrogen, by using titanium or zirconium in the liquid contact part of the reactor, The present inventors have completed the present invention by discovering that the resulting cycloolefins can be produced with high selectivity and high yield by exerting the catalytic performance without any limitation.

Hereinafter, specific embodiments of the present invention will be described.

The wetted portion of the reactor in the present invention means a reaction liquid, that is, a wall portion which is in contact with a slurry phase mainly composed of a hydrogenation catalyst and water in the reactor where the reaction actually proceeds, and the slurry phase and the raw material. , Refers to the wall portion in contact with the mixed liquid of the product and the oil phase, and means at least the inner wall of the reactor. When using a stirring and mixing tank type reactor,
In addition, although accessories such as stirring blades are present in the reactor, they may also use the same material as the above wall material. However, when viewed from an industrial point of view, in a part that is relatively easy to replace, a material having poor durability, for example, a part coated with a fluorine resin may be used. It does not spoil the purpose.

The material of the liquid contact part of the reactor is not necessarily all titanium or zirconium, and the liquid contact surface part of the reactor may be titanium or zirconium.

The material used for these liquid contact parts is titanium or zirconium, but titanium is particularly preferable because it is inexpensive and has good workability. JIS standard product titanium 1, 2, or 3 is preferably used because it is easily available, but a so-called titanium alloy containing a small amount of palladium, vanadium, manganese, or the like may be used.

The monocyclic aromatic hydrocarbon as a raw material for the reaction in the present invention refers to benzene, toluene, xylenes and lower alkylbenzenes having an alkyl group having 4 or less carbon atoms.

Used as a hydrogenation catalyst in the method of the present invention, the particles mainly consisting of ruthenium metal, those obtained by a conventional reduction method from various ruthenium compounds, or the adjustment step or after the adjustment, other metals, For example,
The main component is zinc, or ruthenium containing chromium, molybdenum, tungsten, manganese, cobalt, nickel, iron, copper and the like known per se. Although various ruthenium compounds are not particularly limited, for example, chlorides, bromides, iodides, nitrates, sulfates, hydroxides, oxides, ruthenium reds, or various ruthenium-containing complexes can be used. As the reduction method, reduction with hydrogen gas or chemical reduction with formalin, sodium borohydride, hydrazine or the like can be performed.

Further, in the method of the present invention, if a reduced product of ruthenium containing zinc in advance is used, the yield of cycloolephine can be further increased and it can be effectively used. Such a catalyst is a reduced product obtained by previously adding a valuable ruthenium compound with a zinc compound and then reducing it, and ruthenium is reduced to a metallic state. Valuable ruthenium compounds that can be used are, for example,
Salts such as chlorides, nitrates and sulfates, complexes such as ammine complex salts, hydroxides and oxides, but especially trivalent or tetravalent ruthenium compounds are easily available, and
It is preferable because it is easy to handle. A wide range of zinc compounds can be used, such as salts such as chlorides, nitrates and sulfates, complexes such as ammine complex salts, hydroxides and oxides.

It is not always clear why such a catalyst is effective as a catalyst for producing cycloolefin, but
It can be considered that in the process in which the valuable ruthenium compound is reduced to the metallic state, the coexisting zinc compound appears or increases active sites advantageous for the formation of cycloolefin.

The zinc content in such a catalyst is 0.1 with respect to ruthenium.
It is adjusted to 50% by weight, preferably 2 to 20% by weight. Therefore, the main component of the catalyst is ruthenium, and zinc is not a carrier.

A valuable ruthenium compound containing such zinc is
It may be obtained as a solid by a general coprecipitation method using a mixed solution of a compound of zinc and ruthenium, or may be obtained in the state of a homogeneous solution.

The catalyst in the present invention is prepared by reducing such a valuable ruthenium compound containing zinc until ruthenium becomes a metallic state, and as a reduction method, a general ruthenium reduction method can be applied. . For example, a method of reducing with hydrogen in a gas phase, a method of reducing with hydrogen or an appropriate chemical reducing agent such as NaBH ₄ or formalin in a liquid phase is preferably applied,
A method of reducing with hydrogen in a gas phase or a liquid phase is particularly preferable.

When reducing with hydrogen in the gas phase, it is advisable to avoid extremely high temperature or to dilute hydrogen with other inert gas in order to avoid increasing the crystallite size. When the reduction is carried out in the liquid phase, the valuable ruthenium compound solid containing zinc may be dispersed in water or alcohols, or may be carried out in the state of a uniform solution. At this time, in order to promote the reduction better,
It is advisable to appropriately carry out stirring and heating. Instead of water, an aqueous alkali solution or an appropriate aqueous metal salt solution such as an aqueous alkali metal salt solution may be used.

Similar effects can be obtained by using, as the hydrogenation catalyst, a reduced product of ruthenium containing iron in advance instead of zinc. Such a catalyst can be obtained by the same method as that for the reduced product of ruthenium containing zinc in advance. A wide range of iron compounds can be used, such as salts such as chlorides, nitrates and sulfates, hydroxides and oxides. The iron content in this catalyst is 0.01 to 50% by weight, preferably 0.1 to 20% by weight, based on ruthenium.
Adjusted to. Therefore, again, the main constituent of the catalyst is ruthenium. The diffraction angle in X-ray diffraction of this catalyst has a feature that it shifts to a higher angle side than ruthenium metal.

The hydrogenation catalyst particles as described above are present in the reaction system as crystallites mainly consisting of ruthenium and / or aggregated particles thereof, but in order to increase the selectivity and the yield of the cycloolefins, the crystallites of the crystallites are present. The average crystallite diameter is preferably 200 Å or less, more preferably 100 Å or less. Therefore, the average crystallite diameter is calculated by the Scherrer formula from the spread of the diffraction line width obtained by a general method, that is, the X-ray diffraction method. Specifically, when the CuKα ray is used as the X-ray source, it is calculated from the spread of the diffraction line having a maximum at a diffraction angle (2θ) of around 44 °.

The present invention requires the presence of water. Although the amount of water varies depending on the reaction mode, it can be present in an amount of 0.01 to 100 times by weight with respect to a commonly used monocyclic aromatic hydrocarbon. The organic liquid phase containing water as a main component and the liquid phase containing water are 2
It is necessary to form a phase, and the coexistence of a very small amount of water or a coexistence of a very large amount of water to form a homogeneous phase under the reaction conditions reduces the effect, and if the amount of water is too large, Since it is necessary to increase the size of the reactor, it is practically desirable to coexist 0.5 to 20 times by weight.

In addition, in the present invention, as in the known method already proposed, the periodic table IA element, IIA element, Mn, F
Salts of various metals such as e, Zn and Co may be added. Especially the presence of zinc salts gives good results. Here, as salts of various metals, for example, weak acid salts such as carbonates and acetates, and strong acid salts such as hydrochlorides, nitrates and sulfates are used. The amount used is 1 x 10 with respect to the water coexisting during the reaction.
^-5 times by weight to saturated dissolution amount at room temperature.

Further, in the present invention, it is preferable to react the coexisting aqueous phase under acidic conditions. When the aqueous phase is neutral or alkaline, the reaction rate is significantly reduced, and it is difficult to obtain a realistic production method. In addition, in order to make it acidic, ordinary acids such as hydrochloric acid, nitric acid, sulfuric acid, acetic acid,
It is safe to add phosphoric acid, etc. In particular, sulfuric acid is extremely effective in increasing the reaction rate. The pH of the aqueous phase thus introduced into the reaction system is 0.5 to less than 7, preferably 2 to 6.5.

The partial reduction reaction in the method of the present invention is usually carried out continuously or batchwise by a liquid phase suspension method, but can also be carried out by a stationary phase system. The reaction conditions are appropriately selected depending on the type and amount of the catalyst and additives used, but the hydrogen pressure is usually 1 to 200 kg / cm ² G, preferably 10 to 100 kg / c.
m ² G, and the reaction temperature is room temperature to 250 ° C., preferably 100 to 200 ° C. Further, the reaction time may be appropriately selected by setting a substantial target value of the selectivity and the yield of the target cyclohexane, and is not particularly limited, but is usually several seconds to several hours.

(Effects of the Invention) If titanium or zirconium is used in the connecting portion with the reactor as in the method of the present invention, under the above-mentioned reaction conditions,
This is an industrially extremely valuable one because it can fully exhibit the performance of the hydrogenation catalyst and obtain cycloolefins with high selectivity and high yield.

(Examples) Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 0.4 g of hydrogenation catalyst (average crystallite diameter 55Å) containing 7.4% by weight of zinc obtained by reducing Ru (OH) ₃ containing Zn (OH) ₂ in advance, 320 ml of water, ZnSO ₄ · 7H ₂ O14.
4 g and 80 ml of benzene were charged into an autoclave with an internal volume of 1 where the connections of the reactor wall, stirring blades, etc. were made of JIS standard titanium 2 species, and after heating to 150 ° C,
Hydrogen was introduced under pressure to bring the total pressure to 50 kg / cm ² G, and the reaction was carried out under high speed stirring. The reaction liquid was withdrawn with time and the composition of the oil phase was analyzed by gas chromatography. The results are shown below.

The by-product was cyclohexane.

Example 2 A reaction was carried out in the same manner as in Example 1 except that a container made of zirconium was charged inside the autoclave, and the one in which the liquid contacting portion such as a stirring blade was processed with silconium was used.
The results are shown below.

Comparative Example 1 A reaction was carried out in the same manner as in Example 1 except that an autoclave with an internal volume of 1 in which the liquid contact part was made of SUS-316 was used. The results are shown below.

Example 3 Metal ruthenium particles (average crystallite size 5) as a hydrogenation catalyst
9 Å) Reaction was performed in the same manner as in Example 1 except that 0.4 g was used. The results are shown below.

Comparative Example 2 The reaction was performed in the same manner as in Example 3 except that an autoclave with an internal volume of 1 in which the liquid contact part was made of SUS-304 was used.
The results are shown below.

As described above, the advantage of using titanium for the liquid contact part is clear.

Example 4 After reacting for 120 minutes in the same manner as in Example 1, the reaction liquid was cooled, only the oil phase was removed, and benzene 80 was newly added.
ml was added and reacted for 120 minutes in the same manner. This operation was repeated 4 times, and the result of the 5th reaction was shown below.

Comparative Example 3 The same operation as in Example 4 was performed except that an autoclave having an internal volume of 1 in which the liquid contact part was made of SUS-316 was used, and the results of the fifth reaction are shown below.

The advantages of the present invention are clear.

Claims (1)

[Claims] 1. Titanium or zirconium is used in a liquid contact part of a reactor in partial hydrogenation with hydrogen in the coexistence of water, using particles of ruthenium which is a monocyclic aromatic hydrocarbon as a hydrogenation catalyst. A method for partial hydrogenation of monocyclic aromatic hydrocarbons, characterized in that