JPH03224632A - Method for regenerating catalyst for hydration of olefin - Google Patents

Abstract

PURPOSE:To regenerate a zeolite catalyst at a high rate of regeneration by bringing the catalyst having reduced catalytic activity after use in the hydration reaction of olefin in a liq. phase into successive contact with an aq. soln. of an inorg. alkali and nitric acid. CONSTITUTION:Faujasite, ZSM-5 or other zeolite catalyst having reduced catalytic activity after use in the hydration reaction of olefin in a liq. phase is brought into successive contact with an aq. soln. of an inorg. alkali such as the hydroxide, carbonate or hydrogencarbonate of an alkali metal and an aq. soln. of nitric acid. By this contact, the zeolite catalyst is regenerated at a high rate of regeneration. The pref. amt. of the inorg. salt in the aq. alkali soln. is about 0.5-5 equiv. per 1kg of the catalyst and the pref. temp. of the soln. brought into contact with the catalyst is about 10-150 deg.C. The pref. amt. of the nitric acid brought into contact with the catalyst is about 2-20 mol per 1kg of the catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for regenerating a catalyst when producing alcohol, which is important as a raw material for various chemicals, by hydration of an olefin.

(Prior Art) When a hydration reaction of olefin is carried out in a liquid phase using zeolite as a catalyst, the activity of the catalyst gradually decreases as the reaction progresses. A method for regenerating a catalyst whose activity has decreased is a method of regenerating it in a liquid phase using an oxidizing agent such as hydrogen peroxide, ozone, organic peracid, or nitric acid (Japanese Patent Laid-Open No. 61-234945
zeolite is exchanged with alkali metal ions in advance and then exchanged with a gas containing molecular oxygen for 200~
A method has been proposed in which the alkali metal ions are removed by re-exchange after contact at 600° C. (see Japanese Patent Laid-Open No. 61-234946).

(Problems to be Solved by the Invention) In the prior art, hydrogen peroxide, ozone, and organic peracids in methods using oxidizing agents in the liquid phase are expensive and have the risk of explosion, so they are not safe. There was a problem that required the above equipment. In this respect, the regeneration method using nitric acid, which is cheap and easy to handle, is advantageous, but due to its weak oxidizing power, this method may cause a significant drop in catalyst activity, or may deteriorate over a long period of time and cause repeated regeneration. There was a problem that the regeneration rate was low.Also, by exchanging with alkali metal ions in advance,
The method of subsequently contacting with molecular oxygen requires a long regeneration step, and furthermore, since it includes liquid phase treatment and gas phase treatment, operations such as drying and baking are required, making the operation extremely complicated.

(Means for Solving the Problems) As a result of intensive studies aimed at increasing the regeneration rate of the regeneration method using nitric acid, which is advantageous in terms of cost and safety, the present inventors discovered that the catalyst with decreased activity in the reaction system could be replaced with an inorganic alkali. It has been found that contacting with an aqueous solution and then a nitric acid aqueous solution is effective in increasing the regeneration rate, and the present invention has been completed.

That is, the present invention provides a method for regenerating a catalyst, which comprises, in regenerating a zeolite catalyst subjected to an olefin hydration reaction in a liquid phase, contacting the zeolite with an inorganic alkali aqueous solution and then contacting it with a nitric acid aqueous solution. It is.

The cause of the decrease in zeolite activity in this reaction system is not clearly understood, and it is not clear why contact with an alkaline aqueous solution is effective, but the following may be considered.

In the hydration reaction of olefins in the liquid phase, if the reaction system is used for a long period of time, high-boiling substances gradually accumulate on the catalyst. These high boiling substances clog the pores of zeolite and cause a decrease in activity.

These high-boiling substances include high-boiling ethers and alcohols, which are produced when the alcohol product reacts with olefins, and alkalis are effective in decomposing these substances and in increasing their water solubility by converting them into alcoholades. It is possible that Another cause is that this reaction system is in the presence of high-temperature water, so if it is used for a long time, aluminum will be desorbed from the zeolite crystal lattice, resulting in a decrease in activity due to a decrease in active sites. It is also possible that the alkali treatment serves to return the desorbed aluminum remaining in the zeolite to the crystal lattice.

On the other hand, the role of nitric acid is thought to be as an ion exchange agent to return the alkaline form of zeolite to the acid form due to alkali treatment, and as an oxidizing agent for removing organic matter as mentioned earlier. It will be done.

The inorganic alkaline aqueous solution used in the present invention is not particularly limited as long as it is an aqueous solution of an alkaline inorganic salt, and examples include aqueous solutions of alkali metal hydroxides, alkali metal carbonates, alkali metal hydrogen carbonates, etc. . Among them, preferred are alkali metal hydroxides, and particularly preferred is sodium hydroxide.

The amount of inorganic salt in the inorganic alkaline aqueous solution is in the range of 0.1-10 equivalents per kg of catalyst, preferably 0.5-10 equivalents.
5 equivalents, more preferably 1.0 to 380 equivalents. In particular, when an aqueous sodium hydroxide solution is used, the amount of sodium hydroxide is 0.5 to 5 mol, preferably 0.8 to 3 mol, more preferably 1 to 3 mol, per 1 kg of catalyst.
The range is 2 moles. The amount of this inorganic salt is 0. If the amount is less than 1 equivalent, the regeneration effect will be low, and if it is more than 10 equivalents, the alkalinity will be too strong, resulting in significant crystal destruction due to zeolite dissolution.

The amount of the alkaline aqueous solution is not particularly limited as long as the amount of the inorganic salt is within the range mentioned above, but it is usually 1 to 100 kg, preferably 2 to 50 kg, more preferably 3 to 30 kg per 1 kg of catalyst. range.

There is no particular restriction on the temperature when contacting with the alkaline aqueous solution as long as the liquid state is maintained, but it is usually 0 to 200°C.
Preferably 10-150°C1, more preferably 20-150°C
The range is 100°C.

The embodiment of contacting with the alkaline aqueous solution may be a fixed bed method or a slurry state, but a slurry state is preferable.

In the present invention, after contacting with an alkaline aqueous solution, filtration and washing with water may be performed, or nitric acid may be directly added and contact may be made with nitric acid.

The amount of nitric acid in the present invention is 1 to 3 per kg of catalyst.
The amount is in the range of 0 mol, preferably 2 to 20 mol, and more preferably 5 to 15 mol.

The temperature during contact with nitric acid is usually 0 to 150°C, preferably 10 to 120°C, more preferably 20 to 10°C.
It is in the range of 0°C.

In the present invention, when contacting with nitric acid, a salt such as ammonium vanadate or sodium nitrite may be added as a catalyst.

There are no particular limitations on the embodiment in which the mixture is brought into contact with nitric acid; for example, a fixed bed method or a slurry state may be used, but a slurry state is preferred.

In the present invention, the time for contacting with the alkaline aqueous solution and nitric acid is not particularly limited, but is usually in the range of 10 minutes to 100 hours, preferably 30 minutes to 50 hours, and more preferably 1 to 20 hours.

The regeneration method of the present invention is effective for catalysts whose activity has decreased due to the olefin hydration reaction in the liquid phase. The olefins mentioned here include, for example, chain olefins such as ethylene, propylene, butene, cyclopentene, cyclohexene,
Examples include cyclic olefins such as cyclooctene. Among these, the regeneration method of the present invention is particularly effective in the case of cyclohexene.

The zeolite regenerated in the present invention varies depending on the type of reaction, but for example, faujasite, L-type zeolite, ferrierite, offretite, erionite, zeolite beta, mordenite, ZSM-4, ZS
M-5, ZSM-8, ZSM-11, ZSM-12, Z
Examples include SM-20, ZSM-35, and ZSM-48. Among them, the regeneration method of the present invention is particularly effective for ZSM-
It is 5.

(Effects of the Invention) By using the regeneration method of the present invention, a catalyst whose activity has decreased due to an olefin hydration reaction in the liquid phase can be regenerated at a high regeneration rate using a simple method. This is very advantageous for industrial implementation.

(Example) Next, the present invention will be explained with examples.

Reference Example 1 Water glass (Nato 8.9% by weight, 5iOz28.
9% by weight, Hg062.2% by weight) 79.5kg of N
A homogeneous solution was obtained by adding 39 kg of a0HO and 30 kg of nzo. 600 yen of this solution! A f t (S
O4) 3 ・18Hz06kg and concentrated sulfuric acid 4.5kg
An aqueous solution of was pumped in at room temperature over a period of 1 hour. After that, increase the temperature to 170℃ and 1100rpm.
Crystallization was carried out for 10 hours under stirring conditions. After that, the synthetic slurry was taken out, a part was filtered and washed, and heated at 120°C for 4 hours.
As a result of X-ray diffraction analysis after drying for a period of time, the crystallinity is 35%.
It was ZSM-5.

To 158 kg of the slurry obtained here, 86 kg of water glass was added.
g, NaOH 0,42 kg, plus IIzo 33
Add kg, and add Aj to oto240kg! □(S
O4) 3 ・18H! 06.3 kg and concentrated sulfuric acid 4.5
An aqueous solution containing 1.0 kg was pumped in for 1 hour while stirring at 100 rpm+. Then increase the temperature to 150
The temperature was raised to 0.degree. C., and crystallization was performed for 30 hours while stirring at 1100 rpm. Obtained slurry 4001! , was concentrated to 25% by weight using a rotary filter manufactured by Kotobuki Giken Kogyo Co., Ltd., and then displacement washing was performed at a constant slurry concentration until the pH of the filtrate reached 10.5.

25 kg of nitric acid with a concentration of 63% by weight was added to the slurry obtained.
and 137 kg of Hg were added, ion exchanged at 50'C for 4 hours, and then 30% by weight was added using a rotary filter.
The pH of the filtrate is 4.5 at a constant slurry concentration.
Displacement cleaning was performed until the

In this way, H-type ZSM-5 slurry was obtained.

Reference Example 2 Using the H-type ZSM-5 slurry obtained in Reference Example 1 as a catalyst, a hydration reaction of cyclohexene was carried out under the following conditions.

Reaction section oil/slurry volume ratio - 10/90 Slurry concentration = 30% by weight Cyclohexene supply rate: 1.7 (g-cyclohexene/g-cat-hr) Reaction temperature: 120°C Pressure crab 6 kg/cnl (Nt added Pressure) Reactor:
41 Autoclave made of SUS 304 (having an internal settler in the upper part of the reaction part) Stirring rotation speed: 20 rpm Water was supplied in a pulsed manner so that the slurry concentration was constant.

Immediately after the start of the reaction, the cyclohexanol concentration in the reactor outlet oil was 12.5% by weight, but after that, it increased to 3000% by weight.
After continuous operation for hours, the cyclohexanol concentration was 7.
．． It decreased to 0% by weight.

Example 1 The catalyst that had been operated for 3000 hours in Reference Example 2 was regenerated according to the following procedure.

300 cc of slurry is taken out from the reactor and allowed to stand until the oil and slurry are separated. Only the slurry is taken and heated in a glass container to remove the dissolved oil by stripping. Through this operation, 250 g of a 35% by weight degraded catalyst slurry was obtained. In this slurry, N
aO! l 5. An aqueous solution in which 6 g of LO was dissolved in 50 g of LO was added, and the mixture was treated with an alkaline aqueous solution while stirring at 80'C for 4 hours. At this time, N a O per 1 kg of catalyst
The amount of II is 1.6 mol.

Next, the obtained slurry was added with nitric acid 74 at a concentration of 61% by weight.
．． 3 g was added thereto, and the mixture was treated with nitric acid while stirring at 90°C for 4 hours. At this time, the amount of nitric acid (purity equivalent) per 1 kg of catalyst was 9 mol.

This nitric acid-treated slurry was filtered under reduced pressure using a Nutsche filter, and then washed with water until the pH of the filtrate reached 5.0 to obtain a regenerated catalyst cake with a water content of 40% by weight.

Using this regenerated catalyst, 1! The hydration reaction of cyclohexene was carried out under the same conditions as in Reference Example 2 in a 5IIS 304 autoclave.

As a result, the cyclohexanol concentration in the reactor outlet oil immediately after the start of the reaction was 11.0% by weight.

Example 2 The catalyst that had been operated continuously for 3000 hours in Reference Example 2 was regenerated using the following procedure.

300 cc of slurry was extracted from the reactor, the oil and slurry were separated, and the slurry was filtered under reduced pressure and heated at 2 f Hz.
Washed with water. Thereafter, 146 g of the obtained cake (water content 40% by weight) was mixed with 6.7 g of NaOH and 150 g of H2O.
In addition to the aqueous solution dissolved in g, an alkaline aqueous solution treatment was performed under stirring conditions at 90° C. for 18 hours. Catalyst 1 in this case
The amount of Na1/kg was 1.9 mol. The resulting slurry was filtered and washed with 1120 ml of water.
100 g of nitric acid with a concentration of 61% by weight, 0.1 g of ammonium vanadate, and 2.0 g of sodium nitrite
The mixture was added to the solution dissolved in 100 g and treated with nitric acid under stirring conditions at 90° C. for 15 hours. At this time, the amount of nitric acid (purity equivalent) per 1 kg of catalyst was 12.1 mol.

After filtering this slurry under reduced pressure using Nutsche, the pH of the filtrate was
A cake of regenerated catalyst was obtained by washing with water until the pH value reached 4.8.

Using this regenerated catalyst, hydration reaction of cyclohexene was carried out under the same conditions as in Reference Example 2 in 11 SOS 304 autoclaves.

As a result, the cyclohexanol concentration in the reactor outlet oil immediately after the start of the reaction was 11.3% by weight.

Comparative Example 1 35% by weight after first oil stripping of Example 1
74.3 g of nitric acid with a concentration of 61% by weight was added to 250 g of the degraded catalyst slurry, and the mixture was treated with nitric acid at 90° C. for 4 hours with stirring. At this time, the amount of nitric acid (purity equivalent) per 1 kg of catalyst was 9 mol.

This nitric acid-treated slurry was filtered under reduced pressure using a Nutschie filter, and then washed with water until the pH of the filtrate reached 5.0 to obtain a regenerated catalyst cake with a water content of 38% by weight.

Using this regenerated catalyst, a cyclohexene hydration reaction was carried out under the same conditions as in Reference Example 2 in 11 SUS 304 autoclaves.

As a result, the cyclohexanol concentration in the reactor outlet oil immediately after the start of the reaction was 10% by weight.

This value is considerably lower than that of Example 1, and it can be seen that the effect of the alkaline aqueous solution treatment is large.

Reference example 3 50% by weight Na OII aqueous solution 138 g, Af
t(SOa), 14Hz0118 g, 320 g of precipitated silica powder.

Add 320g of pyrrolidone to the mixture of 750g of uzo, 2! in an autoclave at 110°C without stirring.
Crystallized for 114 days.

After filtering and washing the obtained slurry, it was heated at 120°C for 8
After drying for an hour, X-ray diffraction analysis revealed that the product was ZSM-35.

This dried product was mixed with alumina, water was added, and extrusion molding was performed using an extruder.

As a result, an extrusion molded product containing 65% by weight of ZSt-35 was obtained. This was first fired at 500°C in a nitrogen atmosphere, then ion-exchanged with a 1N ammonium nitrate aqueous solution, and then fired at 600°C in air to form ZSM-35.
A shaped catalyst containing the following was obtained.

Reference Example 4 Using the catalyst of Reference Example 3, a hydration reaction of propylene was carried out under the following conditions.

H! 0/propylene molar ratio = 2/1 WH3V (based on propylene and zeolite) = 0.6
hr. reaction temperature = 170°C pressure crab 70 kg/cff1 The propylene conversion rate was 55% immediately after the start of the reaction, but it decreased to 20% after 300 hours of operation.

Example 3 After flowing nitrogen at 100°C for 1 hour on the catalyst layer after 300 hours of operation in Reference Example 4, a 0.8N NaOH aqueous solution was added.
WH3V (zeolite standard) = 4 at 2hr"80"C
Circulated with a pump for an hour. After that, after circulating H2O under the same conditions for 2 hours, IN nitric acid was added to WH3V=2hr.
-', pumped for 4 hours at 80°C. after that,
820 was circulated under the same conditions for 4 hours to complete the regeneration.

Using this regenerated catalyst, a propylene hydration reaction was carried out under the same conditions as in Reference Example 4.

As a result, the conversion rate of propylene immediately after the start of the reaction was 40%.
Met.

Comparative Example 2 After flowing nitrogen at 100°C for 1 hour through the catalyst layer after 300 hours of operation in Reference Example 4, IN nitric acid was added to the catalyst layer at WH3V=2h.
r-', pumped for 4 hours at 80°C. Thereafter, H2O was circulated under the same conditions for 4 hours to complete the regeneration.

Using this regenerated catalyst, a propylene hydration reaction was carried out under the same conditions as in Reference Example 4.

As a result, the conversion rate of propylene immediately after the start of the reaction was 31%.
Met.

(1 other person)

Claims (2)

[Claims] (1) A method for regenerating an olefin hydration catalyst, which comprises, in regenerating a zeolite catalyst subjected to an olefin hydration reaction in a liquid phase, contacting the zeolite with an inorganic alkaline aqueous solution and then contacting it with nitric acid. (2) The method for regenerating an olefin hydration catalyst according to claim 1, wherein the aqueous inorganic alkali solution is an aqueous solution of an alkali metal hydroxide.