KR970004696B1 - Support recovery from the gas phase selective oxidation catalysts - Google Patents

Abstract

The wasted catalyst, the water, and the ammonia air mixed in the weight ratio of 1:0.6-3:0.1-2 and are tumbled at the speed of 15-100rpm. The property of the catalyst separates water solution and the supporter, and the separated catalyst supporter is washed, dipped in the separated water solution, heated at the temperature of 50-80 degree C. At this time, the solution is stirred up, the water solution and the supporter are tumbled as it is heated, the supporter and the water solution are separated, the supporter is washed in the water, or after washing, dipped in a nitric acid or acetic acid water solution, washed in the water and is dried up to collect a oxidation catalyst supporter.

Description

Support recovery method of gas phase contact partial oxidation catalyst

Fig. 1: Tumbling apparatus used in the embodiment.

* Explanation of symbols for main parts of the drawings

1: catalyst inlet 2: aqueous solution outlet

3: axis 4: motor

5: steam inlet, outlet 6: catalyst bed

7: tube 8: aqueous solution layer

9: perforated plate

The present invention relates to a method for recovering a support from a gas phase contact partial oxidation catalyst which has lost its desired activity. More particularly, the present invention relates to a method for recovering a support without damage from a spent catalyst when a catalyst used for producing acrolein or methacrolein to acrylic acid or methacrylic acid by a selective gas phase oxidation method loses desired activity. The recovered support can be reused as it is for catalyst production.

Catalysts used in the gas phase partial oxidation reaction with severe exotherm generally use a small amount of surface active material and heat transfer material supported or coated with a small amount of active catalyst components. This is to prevent excessive reactions, to quickly remove the heat of reaction, to minimize unwanted complete oxidation reactions at temperature control and high temperatures and to extend the life of the catalyst.

According to U.S. Patents 3,567,772 and 4,410,725, Japanese Patent Laid-Open Nos. 49-11371, 49-169, spherical aluminum sponges having a small surface area and large pores in a mixture of aqueous solutions of catalyst salts in the preparation of a catalyst used for producing acrylic acid by partial oxidation of acrolein, Carborandam, alumina, alumina-silica, silicon carbide, and the like are added and evaporated to dry to support the catalyst component on the support, and finally through a predetermined process to obtain a catalyst.

Most of the commercial catalysts prepared by the above method or similar methods consist of a constant thickness catalyst layer in which the catalytically active component is formed in a special way to increase the wear strength in the pores inside the support and on the surface of the support. These catalysts used in commercial reactors gradually lose their activity over time and have to be replaced periodically. In this case, the reuse of the waste catalyst is not only economically useful, but also greatly reduces the amount of waste generated. Among the recycling methods of waste catalysts, many methods for recovering and reusing economically valuable components from waste catalysts are adopted.

The support used for the above-mentioned partial oxidation catalyst is generally expensive and most of them have high strength and thermal stability, so that the properties such as mechanical strength, surface area, and pore distribution are almost unchanged even after prolonged catalytic reaction, so that they can be recovered without damage from the spent catalyst. It is economical because it can be reused many times.

The present invention relates to a process for effectively recovering a support without changing the physical properties of the support when the catalyst used when preparing acrolein or methacrolein to acrylic acid or methacrylic acid by a selective gas phase oxidation method loses the desired activity.

The catalyst applied to the present invention is represented by the following general formula (I), and the spherical or columnar alumina sponge, carborandam, alumina, alumina-silica having a catalytically active component of 2-10 mm in diameter and a water absorption of 5-30%. And present in the pores and surfaces of a support made of a material such as silicon carbide.

Mo (a) V (b) A (c) B (d) C (e) D (f)... … … … … … … … … … … … … … … … (Ⅰ)

Wherein A represents at least one component of tungsten or niobium, B represents at least one component of iron, copper, bismuth, chromium, antimony and potassium, and C represents at least one component of an alkali metal or alkaline earth metal group. And D represents oxygen.

In addition, a, b, c, d, e, and f represent Mo, V, A, B, C, and D, respectively, and when a = 12, b = 2 at 12, c = 1 at 10, and d = 1 to 6, e = 0 to 4 and f are values determined by the oxidation of other elements.

The support recovery process of the present invention can be largely divided into two steps. It can be divided into a step of removing the catalyst layer of a constant thickness formed on the outer surface of the support, and a step of removing the catalyst in the support pores.

The support recovery process of the present invention is as follows.

Step 1, Tumbling of the Mixture of Waste Catalyst, Water and Ammonia Water

Step 2, Separation of Catalyst Support, Precipitate and Aqueous Solution

Step 3, wash the catalyst support

Step 4, heating the catalyst support with the aqueous solution separated in step 2

Step 5, separation of the catalyst support and the blue aqueous solution

Step 6, wash the catalyst support

Step 7, acid treatment of the catalyst support

The above process is described in detail as follows.

In the first step, the waste catalyst, water and ammonia water (30% ammonia) are mixed at a weight ratio of 1: 0.5-10: 0.1-5, and then tumbling at 10-100 rpm for 10 minutes -3 hours to form the surface of the support. The catalyst layers are abraded to remove the catalyst layers. At this time, the ammonia water dissolves the active ingredient of the catalyst to weaken the bonding strength of the catalyst layer, thereby accelerating the removal of the catalyst layer, and serves to dissolve the catalyst component in the pores. At this time, ultrasonic waves may be used to accelerate the removal of the catalyst layer. In step 2, the precipitate separated from the catalyst layer removed from the support in step 1, an aqueous solution in which the catalyst component is dissolved, and the support are separated. First, the catalyst support is separated from the rest by using a filtration device and a vacuum pump having a hole enough to allow the precipitate to pass easily. The aqueous solution and sediment are then separated separately using a filtration device. When copper ions are present in the aqueous solution, the color of the aqueous solution is dark blue. The precipitate remaining as a filter cake may be dried and then disposed of or disposed of and extracted with effective metals. Recovery of this active ingredient is not within the scope of the present invention. Blue aqueous solution is stored separately. In step 3, the catalyst support separated in step 2 is washed with water. In step 4, the support obtained in step 3 was immersed in the aqueous solution separated in step 2 and heated at 40-90 ° C. for 30 minutes to 8 hours. At this time, the aqueous solution portion is stirred or the support and the aqueous solution are intermittently tumbled to increase the rate at which the catalyst component is dissolved in the pores. Examine the support and visually confirm that all the catalyst components in the pores are dissolved. In step 5, the support is retested and visually observed to confirm that all the catalyst components in the pores are dissolved, and then the support and the aqueous solution are separated using the filtration device used in step 2.

This aqueous solution can be reused. In step 6, the solution is washed with water so that no aqueous solution remains in the pores of the support. When the support is dried without being sufficiently washed, the support may be stained. In this case, the dried support is immersed in 3-50% nitric acid or acetic acid aqueous solution for about 30 minutes, washed with water and dried to recover the support. At this time, the weight of the recovered support should be in the range of 98% -110% of the weight of the catalytically active component from the weight before the recovery process, and the catalyst component should not be observed visually.

In order to effectively carry out the above invention, it is desirable to use an apparatus having the following functions. First, the spent catalyst, water, and ammonia water should be freely added to the vessel up to 10-70% of the volume, and the aqueous solution and sediment generated during the process should be easily removed from the vessel. Second, the catalyst support plate with holes 1-3 mm in diameter smaller than the diameter of the catalyst is attached to the vessel so that only precipitates and aqueous solutions generated during the process can be easily released through the holes. Third, the vessel and mixture above should be tumbling at 10-100 rpm. Fourth, the vessel above can be heated with steam or electricity to heat the mixture in the vessel to 40-90 ° C. Heating can be stopped while tumbling.

An example of a device having such a function is shown in FIG. However, the apparatus for carrying out the invention is not limited to that shown in FIG.

Hereinafter, an embodiment will be described using the apparatus shown in FIG. 1 as follows. The present invention is not limited to the following examples, and the units used may also be converted to larger units used commercially, such as M, KL, and Ton.

<Example 1>

The apparatus used in Example 1 is as shown in FIG. 1 and the internal volume of the vessel is about 30 liters. In the vessel, about 8 mm in diameter, the active ingredient of the new catalyst was Mo ₁₂ V ₅ W ₃ Cu _2.4 Sr _0.8 O, the absorption rate was 20%, and the support was composed of alumina-silica and the weight ratio was 24-26: 76-74. 10 kg of spent catalyst, 10 L of water, and 1 L of 28% ammonia water were added and spun at 60 rpm for 15 minutes. The inlet 2 shown in the figure faced down and the precipitate and the aqueous solution were removed from the vessel, and the precipitate and the blue aqueous solution were separated using a filter. About 10L of water was added through the inlet 1, and the support was tumbled at 15 rpm for 10 minutes, and the water was drained. When 100 random catalysts were taken and observed with a naked eye and a microscope, it was confirmed that the catalyst layer formed on the surface of the support was generally peeled off. When the above samples were dried and weighed, about 12% of the average weight of the 100 spent catalysts was reduced, corresponding to about 48% of the catalyst component. The blue aqueous solution previously separated was filled back into the vessel and the aqueous solution was heated at 60 ° C. for 2 hours with steam. The steam was stopped at 15 minute intervals and the vessel was tumbled at 15 rpm for 1 minute. The support was separated from the blue aqueous solution, washed, and then 100 of the support was taken and observed by visual or optical microscope to remove all catalysts in the processing. The total weight of the support after drying was about 7.5 KG. This corresponds to 75% of the spent catalyst weight, meaning that all catalyst components have been removed.

<Comparative Example 1>

In Example 1, the same amount of spent catalyst, water, and ammonia water were placed in a container. After 30 minutes, the precipitate and the aqueous solution were removed from the vessel, and 10 L of water was added as in Example 1, the support was tumbling at 15 rpm for 10 minutes, and then water was removed. When 100 random catalysts were taken and observed with the naked eye and a microscope, it was confirmed that a considerable amount of catalyst layer remained on the surface of the support.

When the above samples were dried and weighed, about 5.5% of the average weight of the 100 spent catalysts was reduced, corresponding to about 22.2% of the catalyst component.

<Comparative Example 2>

In Example 1, the same amount of spent catalyst and water were placed in a vessel and spun at 60 rpm for 15 minutes. After the precipitate and the aqueous solution was removed from the vessel and 10L of water was added as in Example 1 and the support was tumbling at 15 rpm for 10 minutes, and then water was removed. When 100 random catalysts were collected and observed with a naked eye and a microscope, a substantial amount of catalyst layer remained on the surface of the support as in Comparative Example 1. When weighed by drying, about 7% of the average weight of the 100 spent catalysts was reduced, corresponding to about 28% of the catalyst component.

<Comparative Example 3>

The recovered blue aqueous solution was tested under the same conditions as in Example 1 except that the solution was maintained at room temperature without heating at 60 ° C. When the catalyst was observed, many catalyst components remained in the pores. The total weight of the support after drying was about 8.21 KG. This corresponds to 82.1% of the spent catalyst weight, meaning that about 72% of the catalyst components have been removed.

<Comparative Example 4>

After removing the catalyst layer on the surface of the support in the same manner as in Example 1, 1L of fresh ammonia water was added with 10L of water without using the recovered aqueous solution as in Example 1, and the aqueous solution was heated with steam. At this time, the ammonia water was boiled and the ammonia vapor was severely discharged to stop the experiment.

Claims (1)

A method for recovering a support without damage from a spent catalyst when the catalyst used to prepare acrolein or methacrolein into acrylic acid or methacrylic acid by a selective gas phase oxidation method has lost activity, in the first step, Ammonia water was mixed at a weight ratio of 1: 0.6-3: 0.1-2, and then tumbling at 15-100 rpm. In step 2, the aqueous solution and the support in which the catalyst components were dissolved were separated, and in step 3, the catalyst support was separated in step 2. Was washed with water, the support obtained in step 3 was immersed in an aqueous solution separated in step 4 to step 2 and heated to 50-80 ° C., during heating, the aqueous solution was stirred or tumbled the support and the aqueous solution, and in step 5 the catalyst support And the aqueous solution is separated, and in step 6, the catalyst support is washed with water or washed with water and then immersed in nitric acid or acetic acid aqueous solution and then washed with water and dried How to.