JPS5913577B2 - How to dispose of waste catalyst - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recovering valuable metals contained in a catalyst containing magnesium silicate from a waste catalyst obtained from a hydrotreating process of heavy hydrocarbon oil.

The present inventor previously proposed a catalyst containing sepiolite (magnesium silicate) as a main component as a catalyst for hydrotreating heavy hydrocarbon oil.

This type of catalyst is used for hydrorefining treatment of heavy hydrocarbon oil,
It can be used as a catalyst for various hydrotreating processes such as hydrodemetallization treatment and hydrothermal cracking treatment, but it has a significantly extended catalyst life compared to conventional alumina and silica-alumina catalysts. It has the characteristic of adsorbing a large amount of vanadium and nickel components from hydrocarbon oil before being deactivated.

The present invention takes advantage of the characteristics of the magnesium silicate catalyst to utilize this catalyst as a catalyst for hydrotreating heavy hydrocarbon oil containing metal components, and also to reduce the valuable metal content in the heavy hydrocarbon oil. This was done in order to efficiently recover valuable metals such as vanadium and nickel deposited on this catalyst from the resulting waste catalyst.

Conventionally, methods for recovering valuable metals such as vanadium, molybdenum, and nickel from desulfurization catalysts are known.

For example, Japanese Patent Publication No. 52-5436 proposes the NaCl roasting method, Japanese Patent Application Laid-Open No. 50-102595 proposes the Na 2 SOJ@ roasting method, and Japanese Patent Publication No. 47-21387 proposes the NaCl roasting method. proposed an ammonia water extraction method.

However, all of these conventional methods target waste catalysts using alumina or silica-alumina as carriers, and the methods that target the magnesium silicate-based catalyst of the present invention differ in the component composition of the applied waste catalyst. There are large differences, especially in the amount of vanadium and nickel deposited on the catalyst, and in the case of catalysts with alumina and silica-alumina supports, which are the targets of conventional methods,
This amount is less than 1/3 of that in the case of the catalyst using magnesium silicate as a carrier according to the present invention.

On top of that. Alumina and silica alumina, which are the targets of the conventional method, differ from the magnesium silicate, which is the target of the present invention, in their chemical reactivity, and applying the conventional method to this spent magnesium silicate catalyst does not give good results.

In any case, a suitable treatment method is required for recovering valuable metals from spent magnesium silicate catalysts, but no effective method has been proposed so far.

The present invention is a method for recovering valuable metals that is effectively applied to magnesium silicate-based waste catalysts, which are obtained from the hydrotreating process of heavy hydrocarbon oils using magnesium silicate-based catalysts as the main component. The above waste catalyst
After oxidative roasting at a temperature of 00°C or more and less than 700°C, an aqueous alkali solution is applied to elute the silicon and vanadium contained therein, and the residue containing magnesium and nickel is separated. This is a waste catalyst method characterized by adjusting the pH of the solution to 9 or less and precipitating and separating the silicic acid content to obtain an aqueous vanadate solution.

The term "hydroprocessing of heavy hydrocarbon oil" as used in the present invention is to be interpreted broadly, and includes refining processes such as hydrorefining (hydrodesulfurization) and hydrodemetallization, as well as water treatment for the purpose of lightening. Treatments such as additive pyrolysis are included.

Furthermore, the term "catalyst containing magnesium silicate as a main component" as used in the present invention means a catalyst system containing magnesium silicate as a catalytically active component or a catalyst carrier component.

As the magnesium silicate, synthetic or natural sepiolite is preferably used.

In the case of sepiolite catalysts, in addition to sepiolite itself, modified sepiolite whose composition or skeletal structure has been partially changed in order to improve performance is included.

Examples of modified sepiolite include a fired product of sepiolite, a demagnesized product of sepiolite, a kneaded product of sepiolite, and a metal catalyst component supported on sepiolite or the modified sepiolite.

In the method of the present invention, first, the waste catalyst extracted from the heavy oil hydrotreating process is subjected to oxidation roasting treatment.

In this case, the main metal component of the spent catalyst is Mg % S +
, ■, Ni, or when MO or CO is used as a catalytic active component, these metal components are also included.

Among these metal components, (1) and Ni components are deposited on the catalyst from the hydrocarbon oil during use of the catalyst.

Of course, if these metals are present in the fresh catalyst, some of them are from this beginning, but most of them are derived from the hydrocarbon oil.

The spent catalyst also contains carbon and sulfur, which were deposited on the catalyst during hydrocarbon processing.

The composition of the spent catalyst varies depending on the preparation method of the catalyst and the treatment conditions for heavy hydrocarbon oil. show.

The oxidation roasting temperature of the waste catalyst is 400°C or higher, preferably 400°C or higher.
The temperature is 50° C. or higher, and carbon and sulfur in the catalyst are burned and removed by this treatment.

As mentioned above, the waste catalyst in the present invention contains extremely large amounts of metals and sulfur, but the oxidation roasting temperature is 400
If the temperature is lower than ℃, these will react to produce sulfate, so G) is preferred.

Therefore, in the present invention, a roasting temperature of 400° C. or higher, preferably 450° C. or higher is adopted so that sulfate is not generated or even if it is generated, it is thermally decomposed.

However, there is an upper limit to the roasting temperature in this case, and it is necessary to maintain the roasting temperature below 700°C to obtain an increased vanadium elution rate.

This roasting temperature has a large effect on the vanadium elution rate in the subsequent alkali treatment process, and the roasting temperature is 700℃.
When it comes to exceed this, the vanadium elution rate deteriorates significantly.

Such a phenomenon in which the vanadium content in the waste catalyst becomes difficult to elute with alkali due to high-temperature oxidation roasting is not observed in ordinary desulfurization catalysts, and is only observed in the magnesium silicate catalyst targeted by the present invention. This is a unique phenomenon.

The reason for this is not fully understood, but since the raw material to be treated in the present invention is a magnesium silicate catalyst, it sinters rapidly at high temperatures.

It is thought that at least a part of it changes into stabilized magnesium silicate such as pyroxene, reducing the specific surface area and pore volume of the roasted product, thereby making it inert to alkalis.

Another possible reason is that vanadium pentoxide, which is in a molten state, reacts with magnesium at such high temperatures to produce magnesium vanadate, which has low reactivity with alkalis.

When carrying out this oxidative roasting, a fixed bed, a moving bed, a rotary kiln, a fluidized bed, or any other method may be employed as the roasting method.

As the oxidizing agent, air is usually used, but oxygen or a mixed gas of oxygen and air, or a mixture of these gases diluted with an inert gas such as steam or nitrogen can be used.

This roasting process yields oxidation products containing carbon dioxide gas and sulfur dioxide. Of these, sulfur dioxide is converted into sulfuric acid by a conventional method and then used as a subsequent alkali neutralizing agent in the present invention. Alternatively, it can be recovered by being absorbed into the magnesium hydroxide slurry produced as a by-product at a later stage.

Next, according to the present invention, the waste catalyst oxidized and roasted as described above is treated with an alkaline aqueous solution to elute vanadium and silicon components contained therein, and also contains nickel and magnesium components. Separate the residue.

In the roasted waste catalyst of the present invention, the vanadium contained therein is converted into a form that is extremely soluble in an aqueous alkali solution, and this is easily eluted by the action of an alkali, while the nickel and magnesium components are It remains as a slurry without being eluted.

A conventional solid-liquid separation means such as filtration separation is employed to separate the alkaline aqueous solution containing vanadium and silicon from the residue containing nickel and magnesium.

When carrying out elution treatment of the roasted waste catalyst using this alkaline aqueous solution, it is preferable to maintain the pH at 9 or higher in order to achieve the above object.

If the pH of the alkaline aqueous solution is lower than this, the elution rate of the vanadium component will decrease, and the magnesium and nickel components will be eluted, which is not preferable.

In addition, as the alkali in this case, alkali metal hydroxides and carbonates such as sodium hydroxide, sodium carbonate, and sodium bicarbonate are preferably used, and these may be used alone or in the form of a mixture of two or more. used.

Further, these alkalis can be used in combination with sodium vanadate, sodium sulfate, or sodium salts such as sodium chloride.

Processing conditions such as alkali concentration and processing time are not critical, and are appropriately changed depending on the properties of the roasted waste catalyst, the vanadium content in the waste catalyst, and the like.

In this case, in order to obtain an eluted (extracted) product with good filterability, an aqueous solution containing a sufficient amount of alkali must be added so that the silicate in the form of silicon component 'N a 2S + Os is eluted. It is preferable to use a temperature of 30 to 120° C. so that the reaction between the silicon component and the alkali proceeds smoothly.

If the addition of alkali content is small, the dissolved silicon content will be reduced to N.
This is not preferred because it results in water glass in the form of a2O.nS iO□ (n-2 to 4), giving an eluted product that is difficult to filter.

The vanadium and silicic acid components obtained through the elution step with this alkaline aqueous solution are subjected to the subsequent silicic acid precipitation step, but on the other hand, the residue containing nickel and magnesium components separated from this alkaline aqueous solution is thoroughly washed with water. After removing the eluate and unreacted alkali adhering to it, an appropriate treatment is performed to recover the free metals contained therein.

For example, this residue contains nickel, but in order to recover this nickel, the residue can be brought into contact with aqueous ammonia or an aqueous ammonium salt solution, and the nickel contained therein can be extracted and separated as a nickel-ammonium complex. .

The alkaline aqueous solution containing mainly silicon and vanadium obtained from the alkali treatment step is adjusted to pH 9 or less, preferably 8.0 by adding an acid such as sulfuric acid or hydrochloric acid, or an ammonium salt such as ammonium sulfate or ammonium chloride. The pH is adjusted to 5 or less to produce a solution containing mainly vanadate and a precipitate mainly consisting of silicic acid, and these are separated and recovered.

In carrying out the fractional recovery in this case, the alkaline solution containing silicon and vanadium, which are the raw materials for treatment, is preferably concentrated in advance so that the precipitate can be easily separated from the solution.

The conditions for producing the silicic acid precipitate are appropriately selected depending on the use of the obtained silicic acid, the applied solid-liquid separation conditions and method, etc.

For example, according to a preferred embodiment for forming a silicic acid precipitate, an aqueous sulfuric acid solution containing ammonium sulfate is gradually added to the solution from the alkali elution step at a temperature higher than room temperature, and the solution is aged while being slowly heated. By this, it is possible to precipitate a silicic acid hydrogel that has good separability and is easy to wash.

The silicic acid hydrogel thus obtained can be used as an adsorbent by drying as it is, and can also be used as a catalyst carrier for various reactions.

On the other hand, the solution containing vanadate separated from the silicic acid precipitate can be used as a raw material for vanadium,
Furthermore, the vanadate salt may be separated and recovered by further purification treatment.

In the present invention, other methods for separating vanadate from an alkaline solution containing silicon and vanadium include:
A tertiary amine is added to this solution to extract and separate the vanadate salt, and an alkali such as soda carbonate is added to the extracted amine solution containing the vanadate salt to separate and collect the vanadium salt as a precipitate. There are several methods.

In this case, since the extraction residue mainly contains sodium silicate, it can be used as it is as water glass.

Alternatively, an acid such as sulfuric acid may be added to this product to adjust the pH to an appropriate range to produce a silicic acid hydrogel, which can be recovered and used as silica gel.

In addition, if the waste catalyst used as the raw material for treatment in the present invention contains other metal components such as cobalt and molybdenum, the cobalt and the like can be separated from the vanadium together with the nickel component, and then separated into each metal component by a conventional method. good.

Furthermore, molybdenum and the like are separated from the nickel component along with the vanadium component, and can be separated and recovered using conventional methods.

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

Example 1 Sepiolite containing about 64% of silica (Si02) and about 28% of magnesia (MgO) (most of the remainder being water) was thoroughly kneaded in the presence of water, then molded into granules, and this molded product was Catalysts were prepared by supporting 0.6% and 1.7% of nickel and molybdenum as oxides, respectively.

Using this catalyst, vanadium 29011F, nickel 9
Vacuum residue containing 0 Lord, 8 Lord Iron, and 3.85% sulfur was heated at a hydrogen pressure of 140 kg/crit and a reaction temperature of 380 to 425%.
Hydrogenated at ℃.

The produced oil contains vanadium 10~251'4 and nickel 15~
The composition of the resulting oil, containing 25 pF and 1.2-1.6% sulfur, was kept more or less constant by gradually increasing the reaction temperature.

After approximately 5,500 hours of treatment, the hydrodemetallization activity of the catalyst decreased and it became impossible to obtain a product oil with the above composition, so the reaction was stopped and the spent catalyst was extracted.

The properties of this spent catalyst were as follows.

50g of this waste catalyst was heated to 65g using a natural ventilation roasting furnace.
It was fired at 0° C. for about 1 hour to burn off carbon and sulfur.

The weight of the oxidized roasted product obtained was approximately 27 g.

Next, without pulverizing this fired product, about 20% NaO
When the catalyst particles were poured into a H aqueous solution at 300° C. and maintained at about 60 to 80° C., the catalyst particles were broken into a slurry.

After performing alkaline leaching treatment for about 1 hour, it was passed through the mouth and 0.
The liquid was removed from the precipitate.

In this case, the leaching (eluting) treatment product before filtration had good filterability because the silicon contained therein existed in the form of Na2S i03, and the precipitate could be removed by normal suction filtration treatment. .

When the vanadium and silicon content in the oral fluid was analyzed and the respective recovery rates were determined, the vanadium recovery rate was approximately 100%.
The silicon recovery rate was 91%.

Further, the precipitate was thoroughly washed with warm water and dried at about 200°C to obtain 7.0 g of dry matter.

As a result of analysis, this material was confirmed to contain about 56% nickel as a metal, and was a good nickel raw material.

Next, 20% ammonium sulfate and 1 sulfuric acid were added to the leaching solution containing vanadium and silicon obtained as described above.
Add an aqueous solution containing 0% to keep the pH at 8.0, and adjust the pH to 50-6.
The mixture was heated at 0°C for about 10 hours to precipitate silicic acid.

After thoroughly washing this silicic acid precipitate with warm water,
It was dried at 00°C and the dry matter log was obtained.

In addition, when the vanadium content contained in the mother liquor after separating the silicic acid precipitate was analyzed and the recovery rate was determined, it was approximately 1.
It was 00%.

Reference Example When the waste catalyst having the above composition was treated in the same manner as in Example 1 except that the roasting was performed at 950°C for 1 hour, the recovery rate of vanadium in the alkaline leachate was 56%.
It was only recovered.

From this experimental result, the selection of the oxidation roasting temperature is important in order to increase the vanadium recovery rate.
It can be seen that it is best to maintain the temperature below ℃.

Example 2 A waste catalyst having the same component composition as shown in Example 1 was oxidized and roasted for about 2 hours at different roasting temperatures, and then heated to 50% Na.
2 Perform vanadium leaching treatment using CO body solution,
The leachate was separated from the residue, and the vanadium contained in the leachate was analyzed to determine the vanadium recovery rate.

Claims (1)

[Scope of Claims] 1. In a catalyst containing magnesium silicate as a main component, the waste catalyst obtained from the hydrogenation process of heavy hydrocarbon oil is oxidized and roasted at a temperature of 400°C or higher and lower than 700°C, and then An aqueous alkali solution is applied to elute the silicon and vanadium contained therein, and the residue containing magnesium and nickel is separated, and the resulting solution is then adjusted to pH 9 or less to precipitate the silicic acid. A method for treating a waste catalyst, which comprises separating and obtaining an aqueous solution of hexanadate. 2. The method according to claim 1, wherein the alkaline aqueous solution contains at least one alkaline substance selected from NaOH%Na2COs and NaHCO3. 3. The method according to claim 1 or 2, wherein pH adjustment is performed using a mineral acid or an ammonium salt of a mineral acid. 4. The method according to any one of claims 1 to 3, wherein the waste catalyst is a sepiolite-based catalyst whose activity has decreased due to the accumulation of vanadium and nickel.