JPH032014B2 - - 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, the present invention relates to a method for regenerating a catalyst, which comprises treating a zeolite catalyst that has been subjected to an olefin hydration reaction in a liquid phase with an oxidizing agent in the liquid phase. (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, a so-called air calcination method, which is a calcination treatment at a high temperature using a gas containing molecular oxygen, has been 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, the physical properties of the zeolite change because the catalyst is treated at high temperature in an oxidizing atmosphere. Specifically, a part of the Brønsted acid sites, which are one of the hydration reaction active sites of the zeolite, are changed into Lewis acid sites by 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 inventors have discovered that by treating with an oxidizing agent in the liquid phase, it is possible to regenerate at a significantly higher regeneration rate than conventional methods, leading 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 present invention relates to a catalyst regeneration method characterized by treatment with an oxidizing agent in a liquid phase. While conventional regeneration methods show only low regeneration rates, the present invention shows a substantially high regeneration rate by treating with an oxidizing agent in the liquid phase.
The reason why the liquid-phase oxidizing agent treatment used in the present invention shows a high regeneration rate is not clear, but it is presumed to be as described below. 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. means 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,
It is believed that even relatively mild oxidation, such as the treatment with an oxidizing agent in the liquid phase in the present invention, can convert it into an oxidized substance that can be released from the catalytic active sites. Furthermore, the regeneration method of the present invention does not affect the physical properties of the zeolite itself, unlike the conventional calcination treatment using a gas containing molecular oxygen at a high temperature. Therefore, it is considered that oxidizing agent treatment exhibits a high regeneration rate due to its high ability to remove poisonous substances. 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. The exchangeable cation species of the zeolite used in the present invention are usually proton exchange type, but include alkaline earth elements such as Mg, Ca, and Sr, rare earth elements such as La and Ce, Fe, Co, and Ni. ,Ru,
It is also effective to exchange with at least one cation species selected from group elements such as Pd and Pt. Alternatively, it is also effective to contain Ti, Zr, Hf, Cr, Mo, W, Th, etc. 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. It is. 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. Therefore, when the present invention is applied to the regeneration of a zeolite catalyst that has been subjected to a hydration reaction of a cyclic olefin in a liquid phase, the practical effects are particularly large. 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 the equilibrium of the hydration reaction and an increase in side reactions, etc., but a high temperature is advantageous from the viewpoint of the reaction rate. In the present invention, usually
Catalysts used for hydration reactions are used at reaction temperatures of 50-250°C. As the type of oxidizing agent in the present invention, those commonly used in oxidation reactions of organic compounds can be used. Further, an oxidizing agent containing a metal ion that performs an exchange reaction with the exchangeable cation of the zeolite, thereby reducing the acid strength and acid amount of the zeolite, can also be used by performing proton exchange after the oxidation treatment. Further, it is preferable that the catalyst can be easily separated from the catalyst by washing after the oxidation treatment. Therefore, in the present invention, hydrogen peroxide, ozone, organic peracids, lead tetraacetate, periodic acid, permanganate, nitric acid, nitrous acid, nitrogen oxides, etc. are preferably used as the oxidizing agent; Preferably hydrogen peroxide or ozone is used. When hydrogen peroxide or ozone is used as the oxidizing agent, even if the oxidizing agent remains after the treatment, it can be removed very easily by thermal decomposition, which is preferable. Furthermore, it is also effective to add a catalyst or promoter for the purpose of increasing the rate of oxidant treatment. In the present invention, the conditions for treating the catalyst with reduced activity with an oxidizing agent are that the catalyst and the oxidizing agent must be present in the same liquid phase. In addition, a relatively high reaction temperature is desirable from the viewpoint of processing speed, and a low temperature is advantageous from the viewpoint of loss due to thermal decomposition of the oxidizing agent.
In the present invention, the treatment temperature of the oxidizing agent treatment is 0 to 100°C.
is preferred. In addition, the pH of the liquid phase is not particularly specified, and different values are selected depending on the type of oxidizing agent used, but the structure of the zeolite may change or be destroyed under strongly alkaline conditions. Therefore, oxidizing agent treatment is usually carried out at pH 13 under the following conditions. In the present invention, the concentration of the oxidizing agent is not particularly defined, but from the viewpoint of reaction rate and decomposition of the oxidizing agent, it is expressed as the amount of the oxidizing agent in the liquid phase excluding zeolite, and is preferably 0.001 to It is used at 70% by weight, more preferably from 0.1 to 40% by weight. In the present invention, as the liquid constituting the liquid phase in the oxidizing agent treatment, a solvent having sufficient solubility of the oxidizing agent and sufficient polarity to dissolve the oxidizing substance generated by the oxidizing agent treatment of the catalyst with reduced activity is used, Preferably, aliphatic halides such as chloroform and methylene chloride, alcohols such as methanol and ethanol, ethers such as diethyl ether and tetrahydrofuran, carboxylic acids such as acetic acid, or water are used. After performing the oxidizing agent treatment according to the present invention, it is effective to wash the treated solvent with a polar organic solvent or water. Furthermore, drying or baking may be performed after washing. Furthermore, when the oxidizing agent treatment is carried out under alkaline conditions, it is preferable to wash and replace with an acid afterwards. Alternatively, it is also effective to perform an oxidizing agent treatment after exchanging with an alkali metal in advance, and then remove the alkali metal by further exchange. The reaction mode of the oxidizing agent treatment in the present invention includes a fluidized bed type, a stirring batch type, a continuous type, etc.
This is done using commonly used methods. In the present invention, when performing oxidizing agent treatment, the quantitative ratio of the oxidizing agent and the activity-reduced catalyst to be treated varies depending on the rate of activity reduction, desired regeneration rate, and treatment temperature, and cannot be uniquely defined. Generally, the weight ratio of the oxidizing agent used to the deactivated catalyst being treated is between 0.01 and 20. Further, the treatment time in the present invention varies depending on the reaction temperature, etc., but is preferably about 15 minutes to 50 hours. (Example) Hereinafter, the present invention will be specifically described by showing Examples and Comparative Examples. Reference example 1 To a mixture of 7780g of No. 3 sodium silicate and 9700g of water,
225g of aluminum sulfate, 2290g of sodium chloride,
98g concentrated sulfuric acid, tetrapropylammonium bromide
A mixture of 266 g and 13260 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. Based on fluorescent X-ray analysis of the catalyst obtained above.
The SiO ₂ /Al ₂ O ₃ ratio was 63. 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 10.4% by weight. Furthermore, the concentration of cyclohexanol in the discharged oil after 2100 hours was 8.1% 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, 30 g of water, and 15 g of cyclohexene were charged into a stirring autoclave with 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. Summer. After the reaction, the product was analyzed by gas chromatography. The results are shown in Table 1. Examples 1 to 9 The zeolite used in the hydration reaction in Reference Example 2 was recovered, filtered and washed with water, and then regenerated with an oxidizing agent. That is, after charging 15 g of the recovered zeolite, a solvent, and an oxidizing agent into a glass autoclave with an internal volume of 100 ml, the temperature is raised to the processing temperature while stirring, and the temperature is maintained at the processing temperature for a predetermined period of time (addition method A). Alternatively, 10 g of recovered zeolite and a solvent are charged into the above autoclave, the temperature is raised to the processing temperature while stirring, and then the oxidizing agent is added little by little, and after the addition is completed, the method is kept at the processing temperature for an additional 2 hours (addition method B). Regeneration was performed by In addition, washing with water and the like were performed as post-treatment. Furthermore, using 10 g of the zeolite after the regeneration treatment, the hydration reaction activity was measured in the same manner as in Reference Example 3 to evaluate the regeneration treatment. In all cases, the product was only cyclohexanol, and no other products could be detected. Table 1 shows the type of oxide in the regeneration, the treatment conditions, and the results of the hydration reaction performed 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 was placed in a quartz glass tube and heated to 520° C. for 6 hours in a tube furnace while flowing a mixed gas of dry air and nitrogen (1:4) at a flow rate of 1/min at normal pressure. The zeolite after cooling was pure white, and no residual coke was observed when observed using an optical microscope. Furthermore, powder method X-ray diffraction measurements showed the same pattern and intensity as unused zeolite. Also,
The zeolite SiO ₂ /Al ₂ O ₃ ratio measured by X-ray photoelectron spectroscopy and X-ray fluorescence analysis showed the same value as the unused zeolite. 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】

[Table] (Effects of the invention) According to the present invention, when regenerating a zeolite catalyst subjected to an olefin hydration reaction in a liquid phase, by treating it with an oxidizing agent in a liquid phase, it is possible to It can be played back at a relatively high playback rate.

[Brief explanation of the drawing]

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

Claims (1)

[Scope of Claims] 1. A method for regenerating a catalyst, which comprises treating a zeolite catalyst subjected to an olefin hydration reaction in a liquid phase with an oxidizing agent in the liquid phase. 2. The method according to claim 1, wherein the oxidizing agent is hydrogen peroxide. 3. The method according to claim 1, wherein the oxidizing agent is ozone. 4 Claim 1 in which the oxidizing agent is an organic peracid
The method described in section. 5. The method according to claim 1, wherein the oxidizing agent is nitrogen oxide, nitric acid, or nitrous acid.