JPS61234945A - Regenerating method for catalyst - Google Patents

Abstract

PURPOSE:To regenerate a zeolite catalyst used in the hydrating reaction of olefin in a liquid phase in the high degree of regeneration by treating the zeolite catalyst with an oxidizing agent in the liquid phase. CONSTITUTION:In case of regenerating the zeolite catalyst used in the hydrating reaction of olefin in a liquid phase, it is treated with an oxidizing agent such as H2O2 and O3 in a liquid phase such as an aqueous phase or an oily phase. Thereby a poisonous substance for an active site of the catalyst which is a cause of the activity decrease in the hydrating reaction of olefin in the liquid phase is separated from the active site of the catalyst by means of the comparatively mild oxidation and converted into an oxidized substance. Therefore the catalyst can be regenerated in the high degree of regeneration.

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) Olefin hydration reaction is a method for producing a corresponding alcohol from an olefin and water. 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 to use it as
0828° Japanese Patent Publication No. 58-124723. JP-A-58-1
94828 etc.). In this case, if zeolite is used as a catalyst for an 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, in the above-mentioned calcination treatment, the degree of activity recovery is low, and the method is still insufficient. In particular, the method for regenerating the catalyst used for the hydration reaction in the liquid phase That leaves a problem. That is, in the air calcination method, the physical properties of the zeolite change because the catalyst is treated in an oxidizing atmosphere at high temperatures. Specifically, a part of the Brønsted acid sites, which are one of the active sites for the hydration reaction of zeolite, are changed into siliceous acid sites by the dehydration reaction. Even when the zeolite modified in this way is treated with water, it does not exhibit its original hydration reaction activity. That is, in the conventional air calcination method, it is possible to remove the organic compounds accumulated on the catalyst, but the industrial catalyst for the olefin hydration reaction in the liquid phase essentially reduces the hydration reaction active sites. This is extremely insufficient as a regeneration method.

(Means for Solving the Problems) As a result of extensive 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 present 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, and have completed the present invention.

That is, 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 the liquid phase with an oxidizing agent in the liquid phase.

While conventional regeneration methods only show a low regeneration rate, 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 on 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 poisoning substance in the olefin hydration reaction in the liquid phase is different from the commonly known coke deposit in the conversion process of organic compounds using zeolite as a catalyst. It is believed that relatively mild oxidation, such as treatment with an oxidizing agent, can also convert oxidized substances into oxidized substances that can be released from 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, 7-erierite, crystalline aluminosilicate such as ZSM zeolite published by Mopil, and borosilicate are used.

In the zeolite used in the present invention, the exchangeable cation species are usually proton exchange type, but M
g%Ca% Alkaline earth elements such as Sr, rare earth elements such as La%Ce, Fes 00% Nl, Ru, Pd
It is also effective to exchange with at least one cationic species selected from group Ⅰ elements such as sPt. Or T+ % Zr % Hf % Cr s Mo % W
, Th, etc. are also effective.

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 include:
Preferably, olefins having a straight chain or branched structure having 2 to 12 carbon atoms and mounded olefins having 5 to 120 carbon atoms are particularly effective in the case of cyclic olefins. 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 is less effective than the zeolite used for the hydration reaction of chain olefins in the liquid phase. , easy to generate coke. Poisonous substances in the hydration reaction of cyclic olefins reflect the structure of the raw material cyclic olefin, and easily undergo oxidation and dehydrogenation reactions during calcination treatment, and become graphite-like substances that are difficult to calcinate via polynomial aromatic compounds. It is assumed that this is because the substances are easily generated.

Therefore, when the present invention is applied to the regeneration of a zeolite catalyst 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 equilibrium of the hydration reaction and an increase in side reactions, but a high temperature is advantageous from the viewpoint of reaction rate. In the present invention, a catalyst used in a hydration reaction at a reaction temperature of usually 50 to 250C is used.

As the oxidizing agent in the present invention, those commonly used in oxidation reactions of organic compounds can be used. In addition, oxidizing agents containing metal ions that perform an exchange reaction with the exchangeable cations of zeolite, resulting in a decrease in the acid strength and amount of zeolite, can also be used more conveniently by exchanging protons after oxidation treatment. . Further, it is preferable that the catalyst can be easily separated from the catalyst by washing the oxidation treatment stooge. 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, and more preferably Hydrogen peroxide or ozone is used. When hydrogen peroxide or ozone is used as the oxidizing agent, even if the treated ff1K oxidizing agent remains, it is preferable because it can be removed very easily by thermal decomposition.

Furthermore, for the purpose of increasing the speed of oxidizing agent treatment, it is also effective to add a catalyst or a mechanism promoter.

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. 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. Therefore, in the present invention, the processing temperature of the oxidizing agent treatment is 0 to 100C. is preferred.

In addition, the value of p in the liquid phase is not specified, and different values are selected depending on the type of oxidizing agent used, but there is a possibility that the structure of the zeolite will change or be destroyed under strong alkaline conditions. Because of this, oxidizing agent treatment is usually performed at pH
is carried out under the conditions of 13 or less.

In the present invention, the concentration of the oxidizing agent is not particularly specified, but from the viewpoint of reaction rate and decomposition of the oxidizing agent, it is preferably 0.000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000. 001 to 70 is used in an amount of 11% by weight, more preferably 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 chloroform, aliphatic halides such as methylene chloride, methanol,
Alcohols such as ethanol, and diethyl ether,
Ethers such as tetrahydro-7rane, carboxylic acids such as acetic acid, etc.
Acids or water are used.

It is effective to wash the treated catalyst with a polar organic solvent or water after the oxidizing agent treatment according to the present invention.

Furthermore, drying or baking may be performed after washing.

Further, when the oxidizing agent treatment is performed under alkaline conditions, it is preferable to wash and replace with an acid afterwards. Alternatively, it is also effective to treat the trowel that has been replaced with an alkali metal in advance with an oxidizing agent, and then to remove the alkali metal by replacing the trowel again.

The reaction mode of the oxidizing agent treatment in the present invention is a generally used method such as a fluidized bed method, a stirring batch method, or a continuous method.

In the present invention, when performing oxidizing agent treatment, the quantitative ratio of the oxidizing agent to the catalyst with reduced activity to be treated varies depending on the rate of activity reduction, desired regeneration rate, and treatment temperature, and cannot be uniquely defined. , generally expressed as a weight ratio of the oxidizing agent used to the deactivated catalyst being treated, of 0.01.
~20.

Further, the treatment time in the present invention varies depending on the reaction temperature, etc., but is preferably about 1j15 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 No. 3 sodium silicate 77BOf and water 9700F,
Aluminum sulfate 225 F, Sodium chloride 2290
Add a mixture consisting of f,, @ sulfuric acid 982, tetrab-a-bylammonium bromide 266y and water + 3260F,
Mixed with a homogenizer. The resulting gel-like aqueous mixture was charged into an autoclave, and stirred at a circumferential speed of 1.4 rn/
The mixture was heated to 110° C. for 70 hours while stirring at 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.

5i02/Amu0.5i02/Am0. as determined by fluorescent X-ray analysis of the catalyst obtained above. The ratio Fi was 63. Furthermore, it was identified as ZSM-5 zeolite by powder method X-ray diffraction method.

Reference Example 2 A hydration reaction of cyclohexene was carried out using a continuous flow reactor as shown in the drawing.

Zeolite 4001 prepared above and water 12 were placed in a stainless steel autoclave reactor 3 with an internal volume of 5 tons and equipped with a stirring device.
00? and nitrogen gas R1'j! into the system. ! Shita. After raising the temperature of the reactor while stirring at a rotational speed of 50 Orpm to reach a reaction temperature of 120 C, cyclohexene was supplied from the supply pipe 1 at a rate of 1500 f/hr and T[, and the amount of water in the reactor became constant. Water is supplied from the supply pipes 2 as shown in FIG. 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 drawn 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 6 hours after the start of supply of the raw material cyclohexene was 10.4% by weight. Also, 2)
The concentration of cyclohexanol in the discharged oil after 00 hours was 8.1 weight t4.

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, the above H2
sM-5 zeolite 10y, water 301 and cyclohexene 15? were charged into a stirring autoclave with an internal volume of 100 m, and after replacing the air in the system with nitrogen, a hydration reaction was carried out at 120 C with stirring for 30 minutes. 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 completely recovered, filtered, washed with water, and then regenerated with an oxidizing agent. That is, after charging the recovered zeolite 151, a solvent, and an oxidizing agent into a glass autoclave with an internal volume of 100 d, 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). Or 10f of zeolite recovered to the above autoclave! and a solvent were charged, the temperature was raised to the processing temperature while stirring, the oxidizing agent was added little by little, and after the addition was completed, the processing temperature was maintained for an additional 2 hours (addition method B) for regeneration. In addition, washing with water and the like were performed as post-treatment. Furthermore, using the zeolite 102 after the regeneration treatment, the hydration reaction activity was measured in the same manner as in Reference Example 3, and the regeneration treatment was evaluated. In both cases, the product is only cyclohexanol;
No other products could be detected.

The type of oxide in the regeneration, the treatment conditions, and the results of the hydration reaction performed using the treated catalyst are shown in Table 1.

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 10f was placed in a quartz glass tube, and heated in a tube furnace for 6 hours at a flow rate of 1 t/min at normal pressure with a mixed gas of dry air and nitrogen (1:4).
Heat to C and then.

After being left to cool, the zeolite was pure white, and when observed using an optical microscope, no residual coke was observed.

Furthermore, powder X-ray diffraction measurements showed the same pattern and intensity as virgin zeolite. Furthermore, the SiO,/Am03 ratio of the zeolite measured by X-ray photoelectron spectroscopy and X-ray fluorescence analysis showed the same value as that of 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.

(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, treatment with an oxidizing agent in a liquid phase is performed, compared to the conventional method. can be played back at a high playback rate.

[Brief explanation of drawings]

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

Claims (5)

[Claims] (1) 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. (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) The method according to claim 4, wherein the oxidizing agent is an organic peracid. (5) The method according to claim 1, wherein the oxidizing agent is nitrogen oxide, nitric acid, or nitrous acid.