JP2903326B2 - Regeneration method of olefin hydration catalyst - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to an important alcohol as various chemical raw materials,
The present invention relates to a method for regenerating a catalyst when produced by hydration of an olefin.

(Prior art) When hydration of an olefin is performed in a liquid phase using zeolite as a catalyst, the activity of the catalyst gradually decreases as the reaction progresses. As a method for regenerating the catalyst having reduced activity, a method of regenerating in the liquid phase using an oxidizing agent such as hydrogen peroxide, ozone, organic peracid, nitric acid or the like (see JP-A-61-234945), zeolite Is exchanged with an alkali metal ion in advance, and then contacted with a gas containing molecular oxygen at 200 to 600 ° C., and the alkali metal ion is removed again by exchange (see JP-A-61-234946). Etc. have been proposed.

(Problems to be Solved by the Invention) Among the conventional techniques, hydrogen peroxide, ozone, and organic peracid in the method using an oxidizing agent in a liquid phase are expensive, and there is a danger of explosion. There was a problem that required the above equipment. In this regard, a regeneration method using nitric acid, which is inexpensive and easy to handle, is advantageous.However, in this method, since the oxidizing power is weak, when the activity of the catalyst significantly decreases, or as the degradation regeneration is repeated over a long period of time, There was a problem that the reproduction rate was low. In addition, the method of exchanging with alkali metal ions in advance and then contacting with molecular oxygen involves a long regeneration step, and further includes a liquid phase treatment and a gas phase treatment. However, there was a problem that it became extremely complicated.

(Means for Solving the Problems) The present inventors have conducted intensive studies with the aim of increasing the regeneration rate of the regeneration method using nitric acid, which is advantageous in terms of cost and safety, and as a result, the catalyst whose activity was reduced in the reaction system was converted to inorganic alkali After contacting with an aqueous solution, it was found that contact with an aqueous nitric acid solution was effective in increasing the regeneration rate, and the present invention was completed.

That is, the present invention provides a method for regenerating a zeolite catalyst subjected to an olefin hydration reaction in a liquid phase, wherein the zeolite is brought into contact with an aqueous solution of an inorganic alkali and then with an aqueous solution of nitric acid. It is.

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

In the hydration reaction of an olefin in a liquid phase, if it is used in a reaction system for a long time, a high-boiling substance gradually accumulates on the catalyst. These high-boiling substances block pores of zeolite and cause a decrease in activity. Among these high-boiling substances, high-boiling ethers and alcohols produced by reacting the product alcohol with olefins are included.
It is conceivable that these decompositions, as well as alcoholation, are effective in increasing water solubility. Another reason is that this reaction system is in the presence of high-temperature water, and if it is used for a long period of time, elimination of aluminum from the crystal lattice of zeolite will occur, resulting in a decrease in activity due to a decrease in active sites. As a result, the alkali treatment may serve 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 play a role as an ion exchange agent for returning zeolite that has become alkali type by alkali treatment to an acid type, and as an oxidizing agent for removing organic substances mentioned above. Can be

The inorganic alkali 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 thereof include an aqueous solution of an alkali metal hydroxide, an alkali metal carbonate, and an alkali metal hydrogen carbonate. . Of these, alkali metal hydroxides are preferred, and sodium hydroxide is particularly preferred.

The amount of the inorganic salt in the aqueous inorganic alkali solution is in the range of 0.1 to 10 equivalents, preferably 0.5 to 5 equivalents per kg of the catalyst,
It is more preferably in the range of 1.0 to 3.0 equivalents. Particularly 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 per kg of the catalyst.
Mol, more preferably in the range of 1 to 2 mol. If the amount of the inorganic salt is less than 0.1 equivalent, the regenerating effect is low, and if it is more than 10 equivalents, the alkalinity is too strong and crystal breakage due to dissolution of zeolite becomes remarkable.

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

The temperature at the time of contact with the aqueous alkali solution is not particularly limited as long as the liquid phase is maintained, but is usually in the range of 0 to 200 ° C, preferably 10 to 150 ° C, and more preferably 20 to 100 ° C.

The embodiment in contact with the aqueous alkali solution may be a fixed bed system or a slurry state, but a slurry state is preferred.

In the present invention, after contacting with an alkaline aqueous solution,
Washing may be performed by filtration, or nitric acid may be directly added to contact with nitric acid.

The amount of nitric acid in the present invention is in the range of 1 to 30 mol per kg of the catalyst, preferably 2 to 20 mol, more preferably 5 to 15 mol.

The temperature for contacting with nitric acid is usually in the range of 0 to 150 ° C, preferably 10 to 120 ° C, more preferably 20 to 100 ° 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.

The embodiment when contacting with nitric acid is not particularly limited,
For example, a fixed bed system or a slurry state may be used, but a slurry state is preferred.

In the present invention, the time of contact with the aqueous alkali solution or 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 a catalyst whose activity has been reduced by an olefin hydration reaction in a liquid phase. The olefin mentioned here includes, for example, chain olefins such as ethylene, propylene, and butene, and cyclic olefins such as cyclopentene, cyclohexene, and cyclooctene.
Among them, the regeneration method of the present invention is particularly effective in the case of cyclohexene.

The zeolite to be regenerated in the present invention is different depending on the type of reaction.For example, faujasite, L-type zeolite, ferrierite, offretite, erionite, zeolite beta, mordenite, ZSM-4, ZSM-5,
ZSM-8, ZSM-11, ZSM-12, ZSM-20, ZSM-35, ZSM-48 and the like. Among them, the regeneration method of the present invention is particularly effective,
ZSM-5.

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

(Example) Next, the present invention will be described with an example.

Reference Example 1 Water glass (Na ₂ O 8.9% by weight, SiO ₂ 28.9% by weight, H ₂ O 6
(2.2% by weight) 0.39 kg of NaOH and 30 kg of H ₂ O were added to 79.5 kg to obtain a uniform solution. This solution was charged into a 600-liter autoclave, and while stirring, Al ₂ (SO ₄ ) ₃ · 18H ₂ O 6 kg was added to H ₂ O 225 kg.
And 4.5 kg of concentrated sulfuric acid were pumped in over 1 hour at room temperature. Then raise the temperature to 170 ° C,
Crystallization was carried out for 10 hours under stirring conditions of 00 rpm. After that, the synthetic slurry was extracted, a part of the slurry was filtered and washed,
As a result of X-ray diffraction analysis after drying for hours, the crystallinity was 35%.
ZSM-5.

To 158 kg of the slurry obtained here, 86 kg of water glass, NaO
Add 0.42 kg of H, 33 kg of H ₂ O and add 240 kg of H ₂ O to A
An aqueous solution in which 6.3 kg of l ₂ (SO ₄ ) ₃ .18H ₂ O and 4.5 kg of concentrated sulfuric acid were dissolved was fed in with a pump over 1 hour while stirring at 100 rpm. Thereafter, the temperature was increased to 150 ° C., and crystallization was performed for 30 hours while stirring at 100 rpm. 400l of obtained slurry
Was concentrated to 25% by weight using a rotary filter manufactured by Kotobuki Giken Kogyo Co., Ltd., and then subjected to displacement washing at a constant slurry concentration until the pH of the filtrate reached 10.5.

25 kg of 63% by weight nitric acid and H ₂ O were added to the obtained slurry.
137 kg was added, ion exchange was performed at 50 ° C. for 4 hours, and then concentration was performed with a rotary filter to 30% by weight, and replacement washing was performed at a constant slurry concentration until the pH of the filtrate reached 4.5.

 Thus, an H-type ZSM-5 slurry was obtained.

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

Reaction part oil / slurry volume ratio = 10/90 Slurry concentration: 30% by weight Cyclohexene feed rate: 1.7 [g-cyclohexene / gc
at · hr] Reaction temperature: 120 ° C Pressure: 6kg / cm ² (N ₂ pressure) Reactor: 4l SUS 304 autoclave (with internal settler on top of reaction section) Stirring speed: 200rpm Water supply is slurry Pulsed supply was performed so that the concentration became constant.

The concentration of cyclohexanol in the oil at the outlet of the reactor immediately after the start of the reaction was 12.5% by weight, but after continuous operation for 3000 hours, the concentration of cyclohexanol was reduced to 7.0% by weight.

Example 1 The regeneration of the catalyst operated for 3000 hours in Reference Example 2 was performed in the following procedure.

Withdraw 300 cc of slurry from the reactor, let it stand and separate the oil and slurry.
Heat in a glass vessel to remove the dissolved oil by stripping. By this operation, 250 g of a 35% by weight deteriorated catalyst slurry was obtained. To this slurry, add NaOH 5.6g
Was dissolved in 50 g of H ₂ O, and treated with an aqueous alkali solution at 80 ° C. for 4 hours with stirring. 1 kg of catalyst at this time
The amount of NaOH per unit is 1.6 mol.

Next, 74.3% by weight of nitric acid 74.3% was added to the obtained slurry.
g was added, and nitric acid treatment was performed at 90 ° C. for 4 hours with stirring.
At this time, the amount of nitric acid (in terms of pure product) per 1 kg of the catalyst was 9 mol.

After filtering this nitric acid treated slurry under reduced pressure with Nutsche,
The filtrate was washed with water until the pH reached 5.0 to obtain a regenerated catalyst cake having a water content of 40% by weight.

Using this regenerated catalyst, a hydration reaction of cyclohexene was performed in the same SUS 304 autoclave under the same conditions as in Reference Example 2.

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

Example 2 Regeneration of the catalyst which was continuously operated for 3000 hours in Reference Example 2 was performed in the following procedure.

300 cc of the slurry was withdrawn from the reactor, the oil and the slurry were separated, and the slurry was filtered under reduced pressure and washed with ₂ l of H ₂ O. Then, 146 g of the cake obtained (water content 40% by weight)
Was added to an aqueous solution in which 6.7 g of NaOH was dissolved in 150 g of H ₂ O, and 9
An alkaline aqueous solution treatment was performed under stirring conditions at 0 ° C. for 8 hours. At this time, the amount of NaOH per 1 kg of the catalyst was 1.9 mol. The obtained slurry was filtered, washed with 1 H ₂ O, and then 100 g of 6 lwt% nitric acid and ammonium vanadate.
0.1 g and 2.0 g of sodium nitrite were added to a solution of 100 g of H ₂ O, and nitric acid treatment was performed at 90 ° C. for 5 hours under stirring.
At this time, the amount of nitric acid (pure product equivalent) per 1 kg of catalyst was 12.1
Mole.

After the slurry was filtered under reduced pressure with a nutsche, the pH of the filtrate was
Was reduced to 4.8 to obtain a regenerated catalyst cake.

Using this regenerated catalyst, a hydration reaction of cyclohexene was performed in the same SUS 304 autoclave under the same conditions as in Reference Example 2.

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

Comparative Example 1 35% by weight after the first oil stripping of Example 1
250g of degraded catalyst slurry, 74.3g of 6lwt% nitric acid
Was added and nitric acid treatment was performed at 90 ° C. for 4 hours with stirring. At this time, the amount of nitric acid (in terms of pure product) per 1 kg of the catalyst was 9 mol.

After filtering this nitric acid treated slurry under reduced pressure with Nutsche,
The filtrate was washed with water until the pH reached 5.0 to obtain a regenerated catalyst cake having a water content of 38% by weight.

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

As a result, the concentration of cyclohexanol in the oil at the outlet of the reactor 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 3 138 g of 50 wt% NaOH aqueous solution, 118 g of Al ₂ (SO ₄ ) ₃ .14H ₂ O,
Pyrrolidone in a mixture of 320 g of precipitated silica powder and 750 g of H ₂ O
Add 320g and in a 2l autoclave with stirring
Crystallized at 110 ° C. for 14 days.

The obtained slurry was filtered and washed, dried at 120 ° C. for 8 hours, and then subjected to X-ray diffraction analysis. As a result, the product was ZSM-35.

The dried product was mixed with alumina, added with water, and extruded using an extruder. as a result,
An extruded product containing 65% by weight of ZSM-35 was obtained. First,
After calcination in a nitrogen atmosphere at 500 ° C. and then ion exchange with a 1N aqueous solution of ammonium nitrate, calcination was performed in air at 600 ° C. to obtain a molded catalyst containing ZSM-35.

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

H ₂ O / propylene molar ratio = 2/1 WHSV (based on propylene and zeolite) = 0.6 hr ⁻¹ Reaction temperature: 170 ° C. Pressure: 70 kg / cm ² The propylene conversion immediately after the start of the reaction was 55%, After 300 hours of operation, it dropped to 20%.

Example 3 After flowing nitrogen at 100 ° C. for 1 hour through the catalyst layer after 300 hours of operation in Reference Example 4, 0.8N NaOH aqueous solution was added at WHSV (zeolite standard) = 2 hr ⁻¹ at 80 ° C. for 4 hours. Circulated by pump. Then, after circulating H ₂ O under the same conditions for 2 hours, 1N nitric acid was circulated with a pump at 80 ° C. for 4 hours at WHSV = 2 hr ⁻¹ . Thereafter, H ₂ O was circulated under the same conditions for 4 hours to terminate the regeneration.

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

As a result, the conversion 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, 1N nitric acid was added at 80 ° C. with WHSV = 2 hr ⁻¹ .
Circulated with time pump. Thereafter, H ₂ O was circulated under the same conditions for 4 hours to terminate the regeneration.

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

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

Claims (2)

(57) [Claims] 1. A method for regenerating a zeolite catalyst subjected to an olefin hydration reaction in a liquid phase, wherein the zeolite is brought into contact with an aqueous solution of an inorganic alkali and then with nitric acid. Law. 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.