JP3246979B2 - Catalyst treatment method, treated catalyst and method for producing glyoxal using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing glyoxal and a method for treating a catalyst thereof. More specifically, the present invention relates to a method for producing glyoxal as a silver catalyst, which is immersed in an acid that does not react with silver and then washed with water.

[0002]

Glyoxal is a very useful compound as a fiber processing agent, a paper processing agent, a soil hardening agent or an organic synthetic intermediate. Glyoxal is produced by oxidizing ethylene glycol or acetaldehyde. In the case of glyoxal used for fiber processing, it is necessary to reduce the content of a reaction intermediate, such as glycolaldehyde, which causes yellowing. There are various methods for producing glyoxal by oxidative dehydrogenation of ethylene glycol. For example, a method of oxidizing in the presence of silver crystals having a fixed particle size (0.1 to 2.5 mm) (Japanese Patent Publication No. 61-5401
1) A method of catalytic oxidation with silver crystals in the presence of a vaporized phosphorus compound (Japanese Patent Publication No. 2-49292) has also been proposed. Since silver particles used in the catalyst are expensive, the used catalyst is dissolved in nitric acid, concentrated, recovered as silver nitrate crystals by recrystallization, and silver is regenerated by electrolyzing the silver nitrate solution. A method, a method of using a used silver catalyst as an electrode as it is, and electrolyzing it in an electrolytic solution to precipitate silver particles, and the like are known, and are industrially used as catalysts. However, even if such a silver catalyst is used for a long period of time and then regenerated once solidified and agglomerated, there are many unreacted ethylene glycols and glycolaldehyde as impurities, which is a problem in preparing silver particle catalysts.

[0003] There has also been proposed a method for producing a dialdehyde from a diol using a silver catalyst carried on a carrier. For example, Chem. Ab. vol. 56 3359
d (Soviet Patent No. 136352) and JP-A-57-20
Although the use of diluted ethylene glycol as a raw material is disclosed in 3024 and the like, it has disadvantages such as a large amount of unreacted ethylene glycol in the product. Further, a method for producing glyoxal using silver supported on a carrier as a catalyst is known. Preparation of a supported catalyst includes the following various steps. That is, the carrier is impregnated with a silver salt solution, mixed, dried, calcined, crushed, because it is prepared through such steps as classification, the preparation lot may be different,
If the preparation scales are different, even when operating under similar conditions, glycolaldehyde as an impurity increases, and it is difficult to prepare a catalyst with good reproducibility.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problem of deterioration of a silver catalyst due to its use or reduction of the catalytic ability due to preparation in the case of producing glyoxal by gas phase oxidation of ethylene glycol. That is.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies on the effect of impurities in the silver catalyst on the catalytic activity in the process for producing glyoxal by vapor-phase oxidation of ethylene glycol. The inventors have gained knowledge on a method for treating a catalyst that can produce glyoxal with low reproducibility and low glycol / glycolaldehyde.

That is, the present invention provides a method for treating a silver catalyst for producing glyoxal by oxidative dehydrogenation of ethylene glycol, which comprises immersing the silver catalyst in an acid which does not react with silver.
The present invention relates to a silver catalyst for producing glyoxal by oxidative dehydrogenation of ethylene glycol treated by the method, and a method for producing glyoxal, which comprises oxidatively dehydrogenating ethylene glycol in the presence of the catalyst. More specifically, after immersion in hydrochloric acid or acetic acid which does not react with silver, ammonia, hydroxides of alkali metals, carbonates, hydrogen carbonates, hydroxides of alkaline earth metals, aqueous solutions of carbonates or hydrogen carbonates The present invention relates to a method for treating a silver catalyst characterized by washing with such an alkali, and relates to a silver catalyst in which the content of Fe, Cr, and Ni in the treated silver catalyst is 10 ppm or less, respectively. The reaction temperature is 500-700 ° C. in the presence of a catalyst.
In addition, 0.1 to 0.1 as phosphorus to ethylene glycol
The present invention relates to a method for producing glyoxal by oxidatively dehydrogenating ethylene glycol in the presence of 5.0 ppm of a phosphorus compound.

The present invention is characterized in that ethylene glycol is oxidatively dehydrogenated using a silver catalyst having a small amount of impurities. Impurities are removed by treating a carrier with a silver salt solution impregnated with a silver salt solution, drying, calcining, pulverizing, etc., and treating a supported silver catalyst or silver crystals by electrolysis with an acid that does not react with silver, such as hydrochloric acid or acetic acid. be able to. Following the acid treatment, it may be further treated with an alkali to remove impurities. As the alkali, aqueous solutions of ammonia, hydroxides, carbonates, bicarbonates of alkali metals, hydroxides, carbonates or bicarbonates of alkaline earth metals can be used. The method of treatment includes impregnating the catalyst particles with an acid solution, or passing the acid solution through a layer filled with the catalyst particles, but any method may be used as long as impurities in the catalyst can be removed by the acid. . Further, washing with water after the acid treatment or washing with water after the alkali treatment may be performed. However, when treating with ammonia water, it is also possible to omit water washing.

[0008] Impurities of the supported silver catalyst or electrolytic silver are contaminated mainly during operations such as electrolysis, crushing or pulverization, and classification. As impurities in the catalyst, for example, Fe, Ni, C
There are r, Si, and the like, and it is sufficient that the amount of each impurity becomes 10 ppm or less by these processes.

When the amount of impurities contained in the supported silver catalyst or the silver particle catalyst increases, the leakage amount of the raw material ethylene glycol increases even when the catalyst is operated under the same conditions, as compared with the silver catalyst having a small amount of impurities. Is also increased. An oxidative dehydrogenation reaction at a high temperature to reduce these unreacted raw materials or reaction intermediates is not preferred because the yield of glyoxal decreases.
The gas phase oxidation according to the method of the present invention has a reaction temperature of 500 to 700.
C, preferably 560-630C. A reaction at a lower temperature results in an increase in unreacted ethylene glycol and glycol aldehyde, and a reaction at a higher temperature leads to increased production of formalin, carbon monoxide, and carbon dioxide, resulting in a reduced amount of glyoxal.

In the present invention, as molecular oxygen used for oxidative dehydrogenation, pure oxygen or air may be used, but the latter is preferably used economically. In order to obtain glyoxal with a high yield, ethylene glycol and molecular oxygen are diluted with an inert gas to cause a reaction. As the inert gas, a rare gas such as nitrogen, helium, or argon, carbon dioxide, or water vapor is used.

Further, by performing the oxidative dehydrogenation reaction of ethylene glycol in the presence of a phosphorus compound of 0.1 to 5.0 ppm as phosphorus with respect to ethylene glycol, the conversion of ethylene glycol is increased, and in particular, the selectivity of glyoxal is increased. To improve the glycolaldehyde selectivity. The phosphorus compound may be mixed in advance with ethylene glycol in a predetermined amount before the reaction, or may be added to the reaction system separately or separately from ethylene glycol. As the phosphorus compound, for example, trimethyl phosphite, triethyl phosphite,
Methyl phosphate, ethyl phosphate and the like are used. The amount of phosphorus or phosphorus compound added is suitably in the range of 0.1 to 5.0 ppm in terms of phosphorus with respect to ethylene glycol. By the addition of the phosphorus compound, the production of oxidation products such as carbon monoxide and carbon dioxide and decomposition products such as formaldehyde is significantly suppressed, and the production of glyoxal, which is the target product, is compared with the case where these are not added. The yield is significantly improved.

[0012]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Comparative Example 1 The specific surface area was 0.1 m ² / g and the particle size distribution was 150 to 105 μm.
10 kg of silica whose content is 55 wt% and 75 wt% is 10 wt%
The mixture was impregnated with an aqueous silver nitrate solution (5 kg of silver nitrate + 2.5 kg of water), mixed by stirring, and dried at 110 ° C. for 12 hours. The dried powder was heat-treated in the air at 600 ° C. for 30 minutes, cooled, crushed with a granulator and classified. Further, the same operations of impregnation, drying, heat treatment, crushing, and classification were repeated several times to prepare a catalyst having a silver carrying amount of 50 wt% and a specific surface area and a particle size distribution close to those of the raw material. The impurities in the catalyst are 75 ppm as Fe,
It was 16 ppm as Ni and 11 ppm as Cr. 25 ml of the supported silver catalyst was charged into a stainless steel reactor having an inner diameter of 27.4 mm, and the reactor was charged with 100 g / hr of ethylene glycol, 100 g / hr of steam, 180 l / hour of air via an evaporator and a preheater. hr and 450 l / hr of nitrogen were supplied in a downward flow, and the reaction was carried out at a reaction temperature of 600 ° C. After cooling the reaction gas, the product was separated and collected in a water absorption tower. The results show that the ethylene glycol conversion is 99.5% and the glyoxal selectivity is 45.
The selectivity for glycol aldehyde was 1.7%.
The air supply was further increased to 200 l / hr, and the reaction was continued at a reaction temperature of 630 ° C. The analysis of the collected liquid showed that the conversion of ethylene glycol was 99.7%, the selectivity of glyoxal was 32.6%, and the selectivity of glycolaldehyde was 0.53%.

Example 1 The catalyst prepared in Comparative Example 1 was immersed in 6N-HCl for 6 hours and washed with water. Furthermore, it was immersed in 4N-NH3 for 6 hours, washed with water and dried.
The impurities in the catalyst were 3 ppm as Fe, and Ni and Cr were
It was less than 0.1 ppm. 25 ml of this treated catalyst is 27.
A 4 mm stainless steel reactor was charged. After passing through an evaporator and a preheater to this reactor, ethylene glycol 100
g / hr, steam 100 g / hr, air 300 l / hr and nitrogen 450
The reaction was carried out at a reaction temperature of 630 ° C. by supplying l / hr in a downward flow. After cooling the reaction gas, the product was separated and collected in a water absorption tower. The result is an ethylene glycol conversion of 99.
The selectivity was 9%, the selectivity of glyoxal was 40.9%, and the selectivity of glycolaldehyde was 0.09%. 0.5 p as phosphorus
pm of trimethyl phosphite was added, and the reaction was continued at a reaction temperature of 590 ° C. The analysis of the collected liquid showed that the conversion of ethylene glycol was 99.9%, the selectivity of glyoxal was 56.8%, and the selectivity of glycolaldehyde was 0.14%.

Comparative Example 2 A spent silver catalyst was calcined in the air at 700 ° C. for 2 hours to burn and remove attached carbon. Furthermore, using the waste catalyst ground and washed with water as an anode, a voltage of 10 V, a current density of 200 A / m ² (cathode plate), a silver nitrate solution as an electrolyte, and electrolysis at a liquid temperature of 25 ° C. Was classified. The impurities in the electrolytic silver were 23 ppm as Fe, 7 ppm as Ni and 6 ppm as Cr. 17.4 ppm Fe, Ni, and Cr in a stainless steel reactor with an inner diameter of 27.4 mm
In the following, 10 ml of silicon carbide having a particle size of 30 to 145 mesh is used as a support layer for filling the catalyst, and silver crystals having a particle size of 145 to 200 mesh
5 ml was filled as a catalyst layer. After passing through an evaporator and a preheater to this reactor, ethylene glycol 100 g / hr containing 3.0 ppm of trimethyl phosphite as phosphorus, steam 100
The reaction was carried out at a reaction temperature of 580 ° C. by supplying g / hr, 190 l / hr of air and 450 l / hr of nitrogen in a downward flow. After cooling the reaction gas, the product was separated and collected in a water absorption tower. As a result, the ethylene glycol conversion rate was 99.8%, the glyoxal selectivity was 54.2%, and the glycolaldehyde selectivity was
0.34%.

Example 2 The silicon carbide and silver crystals of Comparative Example 2 were immersed in 3N-HCl for 10 hours, washed with water and dried. Impurities in silicon carbide and silver crystals after treatment are 4 ppm as Fe and 0.1 ppm for Ni and Cr
It was below. This silver crystal was used for the inner diameter of 27.
A 4 mm stainless steel reactor was charged. After passing through an evaporator and a preheater to this reactor, ethylene glycol 100 added with 3.0 ppm of trimethyl phosphite as phosphorus was added.
g / hr, steam 100 g / hr, air 190 l / hr and nitrogen
The reaction was carried out at a reaction temperature of 580 ° C. by supplying 460 l / hr in a downward flow. After cooling the reaction gas, the product was separated and collected in a water absorption tower. As a result, the conversion of ethylene glycol was 99.9%, the selectivity of glyoxal was 58.2%, and the selectivity of glycolaldehyde was 0.18%.

[0017]

EFFECTS OF THE INVENTION By using the catalyst treatment method and the treated catalyst of the present invention, the production of glyoxal by oxidative dehydrogenation of ethylene glycol is suppressed in the production of glyoxal in high yield by suppressing the generation of by-products. It is extremely large that it can be used to manufacture industrial products.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshio Miura 1-6 Takasago, Takaishi-shi, Osaka Prefecture Inside Mitsui Toatsu Chemicals Co., Ltd. In Chemical Co., Ltd. (72) Inventor Masato Yamazaki 1-6-6 Takasago, Takaishi City, Osaka Prefecture Mitsui East Pressure Chemical Co., Ltd. (56) References JP-A-60-199846 (JP, A) JP-A-52-17408 ( JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 45/29 B01J 23/50 B01J 37/06 C07C 47/127

Claims (9)

(57) [Claims] 1. A method for treating a silver catalyst for producing glyoxal by oxidative dehydrogenation of ethylene glycol, comprising immersing in an acid that does not react with silver. 2. The method according to claim 1, wherein the acid is hydrochloric acid or acetic acid. 3. A method for treating a silver catalyst for producing glyoxal by oxidative dehydrogenation of ethylene glycol, comprising immersing in an acid which does not react with silver and washing with an alkali. 4. The method according to claim 3, wherein the alkali is an aqueous solution of ammonia, an alkali metal hydroxide, carbonate, bicarbonate, alkaline earth metal hydroxide, carbonate or bicarbonate. 5. A silver catalyst for producing glyoxal by oxidative dehydrogenation of ethylene glycol, which is treated by the method according to claim 1 or 3. 6. The content of each of Fe, Cr and Ni is 10 ppm.
The silver catalyst according to claim 5, which is: 7. A method for producing glyoxal, comprising oxidatively dehydrogenating ethylene glycol in the presence of the catalyst according to claim 5. 8. The method for producing glyoxal according to claim 7, wherein the reaction temperature is 500 to 700 ° C. 9. The method for producing glyoxal according to claim 7, wherein ethylene glycol is oxidatively dehydrogenated in the presence of 0.1 to 5.0 ppm of a phosphorus compound as phosphorus with respect to ethylene glycol.