JPS5845894B2 - Catalyst activation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for activating a chromium oxide-containing catalyst whose activity has decreased by use in a reaction.

More specifically, for example, it can be used to alkylate ferrites and/or compounds by meta-, mer, etc. to easily and relatively quickly convert chromium oxide-containing catalysts with reduced activity without substantially destroying their appearance. The present invention relates to a method of activating the compound over time until it has sufficient activity to be used again.

The following catalysts are known and proposed as chromium oxide-containing catalysts that selectively alkylate phenol.

(% Publication No. 51-12610, Patent Application No. 52-12959
No. 0, No. 145630, No. 155683, and Japanese Patent Application No. 53-6733) When the alkylation reaction of phenols is carried out continuously using such a catalyst containing chromium oxide, the catalyst The activity 11 gradually decreases due to adhesion of oxygen-containing hydrocarbons (hereinafter abbreviated as CHO species) to the catalyst surface and chemical/physical changes in the catalyst active site.

Additionally, when a gas phase catalytic reaction is generally carried out in a flow system, due to the destruction of the catalyst, the uniformity of the reaction may be affected, such as the generation of differential pressure within the reactor and partial changes in the linear gas flow velocity. Situations that cannot be maintained may occur.

The present inventors conducted research on a method to prevent the activity of the chromium oxide-containing catalyst used in the above reaction from decreasing and to prevent the shape from being destroyed, and to improve its continuous use performance. When removing by oxidation using a mixed gas of oxygen and water vapor, the oxygen concentration and oxygen flow rate in the mixed gas are changed according to changes in the proportion of oxygen-owned hydrocarbons adhering to the surface of the catalyst to be regenerated. By supplying a mixed gas with a gas mixture, the generation of excessive heat within the catalyst itself and the catalyst layer, which can cause catalyst destruction, can be minimized, and the catalyst can be activated rationally without prolonging the catalyst regeneration time. I found out what I can do.

The principles of the present invention are as follows: (1) When the amount of two CR species adhering to the catalyst surface is large, a mixed gas with a relatively low oxygen concentration is flowed at a low flow rate to reduce abnormal heat generation within the catalyst itself and the catalyst layer. to let

(11) When the amount of the two CR species attached to the catalyst surface is small,
To shorten the time required for regeneration by flowing a mixed gas with a relatively high oxygen concentration at a high flow rate.

(rlo Even if the amount of the two CR species adhering to the catalyst surface becomes even smaller, complete activation is possible by introducing the specific surface area value at the time of regeneration as a parameter for catalyst regeneration.

(IV) Adding water vapor to the mixed gas prevents the combustion reaction from running out of control even when abnormal heat is generated within the catalyst itself and the catalyst layer.

I can give you 4 points.

That is, the present invention provides a method for catalytically regenerating a chromium oxide-containing catalyst whose activity has decreased when alkylating phenols with methanol, ethanol, etc., with a mixed gas containing oxygen and water vapor. The (1) oxygen concentration and (11) oxygen flow rate in the mixed gas during the (n+1) regeneration of contact with the catalyst are determined according to the following formula as the defined catalyst surface adhesion CHO species ratio (RT) changes. This is a method of changing the catalyst and activating the catalyst.

If the oxygen concentration (PO2) and oxygen flow rate ('02) exceed the above ranges, abnormal heat will be generated on the catalyst surface and within the catalyst layer, causing changes in the physical properties of the catalyst and destruction of the catalyst, resulting in complete failure. I can't hope for any kind of activation.

Further, when the amount is below the above range, the time until activation is completed is prolonged, and the two CR species on the catalyst surface cannot be sufficiently removed, and in this case as well, it cannot be said that the activation is complete.

In the present invention, the chromium oxide-containing catalyst to be activated may be one that is used as a catalyst when alkylating ferrite and/or compounds in the gas phase using an alkylating agent, and whose activity has decreased to some extent. The composition is not limited to chromium oxide alone, but may be any composition containing chromium oxide.

Such catalysts include chromium oxide alone, or Sn, Fe, Mn, Si, At, B, and Ca in it.

Examples include chromium oxide-containing catalysts containing one or more metal oxides such as Mg, Sr, Na, Rb, and Cs, and/or sulfate groups.

This chromium 3 oxide-containing catalyst is used in various shapes, and generally, it can be a sphere, a cylinder, a cylinder, a ring, a rectangular parallelepiped, or a cube, but any shape is acceptable.

In addition, the phenols used in the gas phase catalytic alkylation reaction using such a catalyst include phenols having at least one hydrogen atom in the ortho position,
General formula (If) (wherein R1, R2, R3 and R4 are hydrogen atoms or methyl ethyl n-propyl 1so-propyl,
It represents an alkyl group such as n-butyl, 1so-butyl, tert-butyl, or various aromatic groups.

) is a compound represented by The alkylating agents used are lower saturated alcohols having 1 to 4 carbon atoms, such as meta, mer, ethanol, n-propanol, is.

-propa, /-ru n-buta, nor 1so-buta,
Nord and tert-pig, Mer, etc.

The mixed gas used in the present invention is a mixed gas containing oxygen and water vapor, or a gas mixed with an inert gas. As the inert gas, nitrogen is generally used, and other gases include carbon dioxide and other gases. , helium, neon, argon, etc. may also be used.

The water vapor content in the mixed gas is preferably 0.1 to 99
mol%, particularly preferably 10 to 70 mol%,
The effect of adding water vapor is considered to be to increase the diffusion efficiency of locally generated reaction heat throughout the reaction.

In the present invention, the temperature at which the catalyst to be activated and the mixed gas are brought into contact is generally in the range of 250'C to 700C, preferably in the range of 350C to 600C.

If the contact temperature is higher than this temperature range, the time required for regeneration will be shortened, but changes in the shape and physical properties of the catalyst will occur, and complete recovery of catalyst activity cannot be expected.

On the other hand, if it is low, it becomes very difficult to remove the CH2 species adhering to the surface.

Measurement of carbon monoxide, carbon dioxide, and water generated during catalytic regeneration of a mixed gas with a surface-adhered CHO species superimposed weight chromium oxide-containing catalyst used in the present invention (during regeneration),
You can find out by integrating.

For example, it is possible to measure the weight of CHO species attached to the catalyst used in the alkylation reaction of phenols under the same conditions using the method described above, and set the actual regeneration conditions of the catalyst based on the amount of CHO species attached to the surface. When a tubular reactor is used, the surface properties of a very small number of reaction tubes among a large number of reaction tubes 71i
By measuring the weight of CHO species, it is also possible to set the overall regeneration conditions.

On the other hand, the value of the BET specific surface area of the catalyst during regeneration can be estimated and used from the values before and after activation without knowing the actual value, and this is sufficient.

When regeneration approaches the end, the amount of gas generated decreases, and the determination of the superimposed weight of the surface-attached CHO species becomes inaccurate, catalyst B
Once the ET specific surface area value is known, the end point can be completely determined.

The present invention can generally be used when the surface-attached CH2 species is present almost uniformly on the catalyst layer, and can also be used when a large amount of CH2 species is present in one part of the catalyst layer compared to other parts. However, by using the mixed gas with a low oxygen concentration and performing pretreatment at a low oxygen flow rate, the present invention can be completely related to the present invention.

As described above, according to the present invention, it is possible to almost completely recover the activity and selectivity of a chromium oxide-containing catalyst that has been poisoned by surface-attached CH2 species and whose activity has decreased in a relatively short time without destroying it. Can be done.

Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 10 kg of chromium nitrate nonahydrate, 1 kg of stannous chloride dihydrate, and 1 kg of iron nitrate nonahydrate were dissolved in 300 t of water, and 6 kg of urea was added and boiled on a heater to form a precipitate.

The generated precipitate was washed with water and then dried at about 150° C. for 20 hours.

The dried precipitate was crushed and crushed to a diameter of 4.8 mm by known methods.
It was compression molded into a cylindrical pellet of m11L and height of 3.2 mm.

The thus obtained catalyst was calcined at 550° C. for 5 hours, and then 1 kg was carefully filled into a stainless steel reaction tube with an inner diameter of 2 Lmrn so as not to break.

The BET specific surface area of the catalyst before use in the reaction was 93 (ml&).

A reaction raw material solution prepared with a molar ratio of phenol, meta, and mer of 1:5 was vaporized using a vaporizer whose temperature was adjusted to 250°C, and then heated at 350°C per hour in a reaction tube whose internal temperature was maintained at 380°C. ! The reaction was carried out by introducing the solution at a rate of i/.

The reaction products were analyzed by gas column.

The reaction was stopped 150 hours after the start of the reaction, and the weight of CHO species attached to the surface of the catalyst in the reactor (ωT) and the catalyst BET specific surface area (ST) were examined, and it was found that ωT =
1.013 (kg), ST226 (Precept 4),
As the value of surface-attached CHO species ratio CRT), )jT==
, 4.65×10 was obtained.

Next, the reactor was maintained at 380°C, and deionized water vaporized with a vaporizer was fed into the reactor at a rate of 0.7 C9/ml.
At the same time, air was fed from the top of the reactor at 0.05 (t/ml) to start regeneration.

By tracking the amount of carbon monoxide, carbon dioxide, and water discharged outside the reactor, the remaining deposited CHO inside the reactor can be detected.
Calculate the amount of H2O and use this value to determine the catalyst B at that point.
The ET specific surface area value was estimated and the value of RT** was determined.

The value of RT was gradually decreased and the air flow rate was calculated and increased accordingly.

For example, when RT=IO, 0.1 (t/mvr),
When RT=10, 0.5 (17m1ft)
, RTTiO2', the flow rate was 2.0 (t/ml!t), and regeneration was performed until carbon monoxide and carbon dioxide were no longer detected in the exhaust gas.

The catalyst thus regenerated was subjected to the same conditions as the initial reaction to carry out the reaction.

Table 1 shows the results of repeated reactions and regenerations in this manner.

After repeating the above reaction and regeneration operation 10 times, the catalyst in the reactor was taken out, and almost all catalyst pellets had retained their original shape.

Furthermore, as shown in Table 1, it can be seen that the catalyst activity and selectivity were completely recovered regardless of the number of regenerations.

Example 2 Under the same conditions as in Example 1, the surface-attached CHO species ratio (RT) was made larger than 10, and 0.7 (97 ml) of deionized water and 20 (i/i/l) of deionized water and 20 (i/l) of air were added per 1 kg of catalyst. m
Table 2 shows the results of repeated regeneration and reaction with vt).

After repeating the above reaction and regeneration operation five times, when the catalyst in the reactor was taken out, about 6% of the catalyst pellets were found to have been destroyed.

In addition, as the regeneration and reaction were repeated, it was discovered that a slight pressure difference was generated within the reactor, causing clogging in the catalyst layer.

However, as shown in Table 2, the activity and product selectivity of the catalyst are almost fully recovered regardless of the number of regenerations.

Example 3 Under the same conditions as Example 1, the proportion of CHO species attached to the surface (RT)
Assuming that the value of
Table 3 shows the destruction ratio of the catalyst in the reactor when the regeneration and reaction were repeated.

Example 4 Under the same conditions as Example 1, the proportion of CHO species attached to the surface (RT)
Assuming that the value of is approximately 10, the destruction rate of the catalyst in the reactor when the reaction is repeated by regenerating deionized water at 0.7 (9/mm) and air at i o (z, m) per 1 kg of catalyst. The values are shown in Table 3.

Example 5 Under the same conditions as Example 1, the proportion of CHO species attached to the surface (RT)
Assuming the value of about 5 x IO, per 1 kg of catalyst, 0.7 C11/m of deionized water) and 30 (t/m 1 ft) of air.
Table 3 shows the destruction rate of the catalyst in the reactor when the regeneration and reaction were repeated.

- In any of the above Examples 3 to 5, no obvious decrease in activity or product selectivity was observed by regenerating the catalyst and repeating the reaction.

Comparative Example 1 Under the same conditions as Example 1, the proportion of CHO species attached to the surface (RT
) of deionized water per kg of catalyst, regardless of the value of
Table 4 shows the results when the reaction was repeated by regenerating air at 50 (7/mvt).

After repeating the above reaction and regeneration, when the catalyst in the reactor was taken out, about 23% of the pellets were found to have been destroyed.

However, as is clear from Table 4, the activity and product selectivity of the catalyst are almost recovered regardless of the number of times the catalyst is regenerated.

Claims (1)

[Scope of Claims] 1. A method for catalytically regenerating a chromium oxide-based catalyst whose activity has decreased by contacting it with a mixed gas containing oxygen and water vapor, which is used when alkylating Fe,/-ols with methanol or the like. , m oxygen concentration in the mixed gas during regeneration (n+1) times of contact with the catalyst and (11 ) A method of activating a chromium oxide-containing catalyst by changing the oxygen flow rate according to the formula below.