JPH032015B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a novel method for regenerating a catalyst. More specifically, when regenerating a zeolite catalyst that has been subjected to an olefin hydration reaction in the liquid phase, the zeolite is exchanged with alkali metal ions in advance, and then exchanged with a gas containing molecular oxygen at
The present invention relates to a method for regenerating a catalyst, which comprises contacting at 600° C. and then gradually removing the alkali metal ions by re-exchange. (Prior art) The olefin hydration reaction consists of olefin and water.
This is a method for producing the corresponding alcohol. Conventionally, hydration reactions using homogeneous catalysts using mineral acids have been used as industrial methods for producing alcohol through hydration reactions, but in recent years solid acid catalysts, especially zeolite catalysts, have been used as an alternative. A method has been proposed for use as a method (Japanese Patent Application Laid-open Nos. 57-70828, 1982-124723, 1987-194828, etc.). In this case, if zeolite is used as a catalyst for the olefin hydration reaction in the liquid phase for a long period of time, the reaction activity will gradually decrease due to the accumulation of impurities in the raw materials, and the catalyst will need to be regenerated. Conventionally, as a method for regenerating such a catalyst, firing treatment at high temperature using a gas containing molecular oxygen is generally known. (Problems to be Solved by the Invention) However, the above-mentioned calcination treatment is still an insufficient method, such as a low degree of activity recovery, and is particularly suitable as a method for regenerating a catalyst used in a hydration reaction in a liquid phase. leaves a problem. That is, in the air calcination method, since the catalyst is treated at high temperature in an oxidizing atmosphere, the physical properties of the zeolite change. in particular,
A part of the Brønsted acid sites, which are one of the active sites for the hydration reaction in zeolite, change to Lewis acid sites due to the dehydration reaction. Zeolites modified in this way do not exhibit their original hydration reaction activity even when treated with water. That is, in the conventional air calcination method, although it is possible to remove the organic compounds accumulated on the catalyst, it essentially reduces the hydration reaction active sites, so it is difficult to regenerate the industrial catalyst for the olefin hydration reaction in the liquid phase. As a method, it is extremely inadequate. (Means for Solving the Problems) As a result of intensive research in order to solve the above problems, the present inventors found that in regenerating the zeolite catalyst used in the olefin hydration reaction in the liquid phase, The zeolite is exchanged with alkali metal ions in advance,
Then, by catalyzing it with a gas containing molecular oxygen at a temperature of 200 to 600°C, and then removing the alkali metal ions by re-exchange, it has been shown that regeneration can be achieved at a significantly higher regeneration rate than in conventional methods. This finding led to the completion of the present invention. That is, in the present invention, when regenerating a zeolite catalyst subjected to an olefin hydration reaction in a liquid phase,
The zeolite is exchanged with alkali metal ions in advance, and then exchanged with a gas containing molecular oxygen for 200-600 min.
The present invention relates to a method for regenerating a catalyst, characterized in that the alkali metal ions are removed by re-exchange after contact at .degree. While conventional regeneration methods show only low regeneration rates, processing with the method of the present invention shows a substantially high regeneration rate. Although the reason why the regeneration method used in the present invention exhibits a high regeneration rate is not clear, it is thought to be approximately as follows. The cause of the decrease in activity in the olefin hydration reaction in the liquid phase is the accumulation of poisonous substances at the catalyst active sites. Here, poisonous substances are polar substances and side reaction products that exist in small amounts in raw materials, and by adsorbing or chemically bonding to the catalyst active sites, they result in the hydration reaction at the active sites being inhibited. A substance that obstructs progress. This poisonous substance in the olefin hydration reaction in the liquid phase is used in the conversion process of organic compounds using zeolite as a catalyst.
Unlike the commonly known coke deposit,
Although it is thought that organic substances can be removed by a relatively mild method, organic substances can be removed by the ordinary air calcination method, but as shown in Formula 1, the Brønsted acid site, which is one of the active sites for hydration reaction in zeolite, This results in an irreversible change in the olefin hydration reaction, resulting in a decrease in the activity of the olefin hydration reaction. On the other hand, in the present invention, the zeolite is exchanged with an alkali metal in advance and then brought into contact with an oxygen-containing gas to calcine the organic substance, so the above dehydration reaction essentially does not proceed, and after contact with the oxygen-containing gas, It is thought that activity can be recovered by performing re-exchange. The zeolites used in the present invention are known. For example, zeolites containing different elements such as mordenite, erionite, ferrierite, crystalline aluminosilicate such as ZSM zeolite published by Mobil, and borosilicate are used. In the zeolite used in the present invention, the exchangeable cation species are usually proton exchange type, and some of them are alkaline earth elements such as Mg, Ca, and Sr, and rare earth elements such as La and Ce. ,Fe,
It may be replaced with at least one cationic species selected from group elements such as Co, Ni, Ru, Pd, and Pt. Or Ti, Zr, Hf, Cr, Mo, W,
It may also contain Th and the like. When zeolites exchanged with these cationic species are treated by the method of the present invention, even though the composition of the cationic species changes due to the exchange and re-exchange of some of the cations, the result is that the olefins in the liquid phase are It is sufficient if the activity for hydration reaction can be recovered. The zeolite used in the present invention may be in any form, such as powder or granules. Furthermore, alumina, silica, titania, etc. can also be used as a carrier or binder. The olefin species for the hydration reaction that can be treated in the present invention are preferably olefins having a linear or branched structure having 2 to 12 carbon atoms and cyclic olefins having 5 to 12 carbon atoms, and is particularly effective in the case of cyclic olefins. be. In other words, when regeneration using the conventional air calcination method is attempted, the zeolite catalyst used for the hydration reaction of cyclic olefins in the liquid phase has a lower performance compared to the zeolite used for the hydration reaction of chain olefins in the liquid phase. , easy to generate coke. The poisonous substance in the hydration reaction of cyclic olefin reflects the structure of the raw material cyclic olefin, and it easily undergoes an oxidative dehydrogenation reaction during calcination treatment, and it passes through polycyclic aromatic compounds to graphite, which is difficult to calcinate. It is presumed that this is because it is easy to generate a substance like this. On the other hand, in the present invention, it is essentially impossible to reduce the number of active sites due to firing at a high temperature, so it is possible to perform firing at a higher temperature than in conventional firing methods. That is, the present invention has a particularly large substantial effect compared to the conventional method in regenerating the catalyst subjected to the hydration reaction of cyclic olefin, which was relatively difficult with the conventional calcination method. The hydration reaction conditions that can be used in this reaction are those in which the catalyst is present in a liquid phase consisting of an aqueous phase, an oil phase, or a mixture of both, and the reaction temperature and reaction pressure are particularly specified. isn't it. However, in general, a low temperature is advantageous for the olefin hydration reaction from the viewpoint of equilibrium of the hydration reaction and an increase in side reactions, etc., but a high temperature is advantageous from the viewpoint of reaction rate. In inventions, usually 50
A catalyst used for the hydration reaction is used at a reaction temperature of ~250°C. As a treatment method for the alkali metal exchange step in the present invention, the following methods are usually applied. The zeolite to be treated is treated with a polar medium such as water or an alcohol such as methanol or ethanol, an ether such as diethyl ether, tetrahydrofuran, or 1,2-dimethoxyethane, or a sulfone such as sulfolane, before being subjected to alkali metal exchange. It is preferable to wash it. As the alkali metal source, an alkali metal salt is used. Preferred salts include lithium salts such as lithium chloride, lithium nitrate, lithium sulfate, and lithium acetate; sodium salts such as sodium chloride, sodium nitrate, sodium sulfate, and sodium acetate; potassium chloride, potassium nitrate, potassium sulfate, and potassium acetate; At least one salt selected from potassium salts, rubidium salts such as rubidium chloride, rubidium nitrate, and rubidium sulfate, and cesium salts such as cesium chloride, cesium nitrate, cesium sulfate, and cesium acetate is used. As for the exchange method, the zeolite to be treated is usually immersed in the above aqueous solution of the alkali metal salt, and the exchange proceeds by stirring or standing still. The concentration of the metal salt aqueous solution varies depending on the type of salt used, but is usually 0.0001 to 10 mol/.
Preferably 0.05 to 5 mol/ is used. Normal pressure is normally used during the exchange process, but it is of course possible to perform the process under reduced pressure or increased pressure. The liquid temperature during the exchange process is as follows:
Usually 0~100℃ is used, preferably 20~90℃
is used. Furthermore, the quantitative ratio of the salt to the zeolite used is 0.1 to 100, preferably 1 to 20, expressed as the ratio of the number of moles of the salt to the exchange capacity of the zeolite. The pH of the aqueous solution during alkali exchange treatment is not particularly specified, but the zeolite structure may change or be destroyed under strong alkaline conditions, so it is usually PH13 or lower,
Preferably, the treatment is carried out at a pH of 9 or lower. The treatment time used is 0.1 to 100 hours, preferably 0.5 to 50 hours. Furthermore, it is effective to repeatedly perform the exchange treatment with an alkali metal. It is also effective to prevent salts from remaining on the zeolite by washing the zeolite that has been treated with alkali metal with water before proceeding to the next step. In the present invention, as a treatment method for the step of contacting zeolite with a gas containing molecular oxygen, the following methods are usually applied. After drying the zeolite which has been exchanged with alkali metal ions in advance, it is subjected to a fixed bed or fluidized bed reaction using a gas flow method using any type of heating device such as a tube furnace or a matzuru furnace. The oxygen concentration in gases containing molecular oxygen is usually
0.01 to 90 mol%, preferably 1 to 30 mol%
used in As the gas component other than molecular oxygen, N ₂ , He, Ar, and air are preferably used,
It is desirable that moisture in the gas be removed in advance. Further, the gas flow rate is 0.25 to 10 hr ⁻¹ expressed in weight hourly space velocity (WHSV) for zeolite, and the treatment temperature is 200 to 600°C. The treatment time is usually 1 to 96 hours, preferably 2 to 20 hours. The above treatment is usually carried out under normal pressure, but of course it can also be carried out under reduced pressure or increased pressure. In the present invention, as a treatment method for the step of removing the alkali metal by re-exchange, the following methods are usually applied. That is, as the cation species used for re-exchange to remove alkali metal ions, at least one cation species selected from broton, ammonium ions, alkaline earth elements, rare earth elements, and group elements is usually used. Ru. Particular preference is given to using protons. The re-exchange method is the same as the above-mentioned exchange with an alkali metal, except that the cation source is different. That is, when the cation source is a proton, an aqueous solution of an acid such as hydrochloric acid, nitric acid, or sulfuric acid is used. Further, when the cation source is a metal ion, an aqueous solution of a hydrochloride, nitrate, sulfate or the like of the corresponding cation is used. The concentration, temperature, pressure, and ratio of these acid aqueous solutions or metal salt aqueous solutions to zeolite are the same as in the alkali metal exchange treatment described above. It is also effective to repeat the re-exchange process. Furthermore, the reexchanged zeolite may be subjected to operations such as washing with water, drying, and calcination before being subjected to the hydration reaction of the cyclic olefin again. (Example) Hereinafter, the present invention will be specifically described by showing Examples and Comparative Examples. Reference example 1 To a mixture of 7785g of No. 3 sodium silicate and 9690g of water,
225g of aluminum sulfate, 2285g of sodium chloride,
98g concentrated sulfuric acid, tetrapropylammonium bromide
A mixture of 266 g and 13255 g of water was added and mixed with a homogenizer. The resulting gel-like aqueous mixture was charged into an autoclave and stirred at a peripheral speed of 1.4.
The mixture was heated to 110° C. for 70 hours while stirring at m/sec.
The obtained crystalline aluminosilicate was washed with water, dried, and calcined, and then ion-exchanged with a 1N aqueous solution of hydrochloric acid to obtain a proton-exchange type crystalline aluminosilicate. SiO ₂ / by fluorescence X-ray analysis of the catalyst obtained above
The Al ₂ O ₃ ratio was 64. Furthermore, it was identified as ZSM-5 zeolite by powder method X-ray diffraction method. Reference Example 2 Using a continuous flow reactor as shown in the drawing,
The hydration reaction of cyclohexene was carried out. The zeolite prepared above was placed in a stainless steel autoclave reactor 3 with an internal volume of 5 and equipped with a stirring device.
400g and 1200g of water were charged, and the inside of the system was replaced with nitrogen gas. The temperature of the reactor was increased while stirring at a rotational speed of 500 rpm to reach a reaction temperature of 120°C, and then cyclohexene was added from supply pipe 1 at a rate of 1500 g/hr, and the amount of water in the reactor was kept constant. , water is supplied from the supply pipes 2, respectively. The reaction mixture overflowing from the reactor is introduced into the liquid-liquid separator 5 through the overflow pipe 4. The oil phase in the separated reaction mixture is taken out of the system through a discharge pipe 6, and the catalyst-water phase is recovered into the reactor through a return pipe 7. The concentration of cyclohexanol in the discharged oil 3 hours after the start of supply of the raw material cyclohexene was 10.2% by weight. Furthermore, the concentration of cyclohexanol in the discharged oil after 1900 hours was 7.9% by weight. Reference Example 3 A batch hydration reaction was carried out using the HZSM-5 zeolite synthesized in Reference Example 1 as a catalyst. That is, 10 g of the HZSM-5 zeolite and 30 g of water.
and 15 g of cyclohexene were charged into a stirring autoclave having an internal volume of 100 ml, and after replacing the air in the system with nitrogen, a hydration reaction was carried out at 120° C. for 30 minutes with stirring. After the reaction, the product was analyzed by gas chromatography. The results are shown in Table 1. Examples 1 to 5 The zeolite used in the hydration reaction in Reference Example 2 was recovered, filtered, washed with water, and then subjected to regeneration treatment. Specifically, (1) 15 g of the recovered zeolite, 500 ml of water, and an alkali metal salt were added to a glass container with an internal volume of 1000 ml, and heated to a predetermined temperature while stirring on a hot water bath. After stirring for a predetermined time, the zeolite was filtered, washed with water, and subjected to post-treatments such as drying at 120° C. for 5 hours. (2) The zeolite treated in (1) above is placed in a quartz glass reaction tube, and heated to a specified temperature on a tube furnace while flowing a mixed gas of dry air and dry nitrogen gas at a specified flow rate and at normal pressure. After heating for a predetermined time, it was allowed to cool. (3) Add the zeolite treated in (2) above, 500 ml of water, and a cation source to a glass container with an internal volume of 1000 ml,
The mixture was heated to a predetermined temperature while stirring on a hot water bath. After stirring for a predetermined time, the zeolite was subjected to post-treatments such as filtering, washing with water, and drying. Using 10 g of the regenerated zeolite, the hydration reaction activity was measured in the same manner as in Reference Example 3.
We evaluated the regeneration process. In either case,
The product was only cyclohexanol, and no other products could be detected. Table 1 shows the regeneration conditions and the results of the hydration reaction using the treated catalyst. Comparative Example The zeolite used in the hydration reaction in Reference Example 2 was recovered, filtered, washed with water, dried, and then subjected to air calcination treatment. That is, the dried recovered zeolite 10
g into a quartz glass reaction tube, and mixed gas (1:4) of dry air and dry nitrogen gas at 1N/
The mixture was heated to 520° C. for 8 hours in a tube furnace while flowing under normal pressure at a flow rate of min. The zeolite after cooling was pure white, and no residual coke was observed when observed using an optical microscope. A hydration reaction was carried out in the same manner as in Reference Example 3, except that the zeolite regenerated above was used. The results are shown in Table 1.

[Table] (Effects of the invention) According to the present invention, when regenerating a zeolite catalyst that has been subjected to an olefin hydration reaction in a liquid phase, the zeolite is exchanged with alkali metal ions in advance, and then the zeolite containing molecular oxygen is exchanged with alkali metal ions. By bringing the alkali metal ions into contact with a gas at 200 to 600° C. and then removing the alkali metal ions by re-exchange, regeneration can be achieved at a higher regeneration rate than in conventional methods.

[Brief explanation of the drawing]

The drawing is a flow sheet showing the apparatus used in the reference example.

Claims (1)

[Claims] 1. In regenerating the zeolite catalyst subjected to the olefin hydration reaction in the liquid phase, the zeolite is exchanged with alkali metal ions in advance, and then brought into contact with a gas containing molecular oxygen at 200 to 600 °C, A catalyst regeneration method characterized in that the alkali metal ions are removed by re-exchange.