KR101748286B1 - Method for Preparing Poly Aluminum Sulfate Silicate Using Waste Catalysts of Aluminum Oxide and Silicon Oxide - Google Patents

Abstract

The present invention discloses a process for preparing aluminum polysulfate silicate using aluminum oxide and a silicon dioxide scavenging catalyst. More particularly, the present invention relates to a process for producing polyphosphoric acid, which can be produced at a cost lower than the production cost of a currently used commercial coagulant by using aluminum oxide and a silicon dioxide scavenging catalyst, satisfying the criteria of a water treatment agent notified by the Ministry of Environment, Discloses a process for producing aluminum silicate.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a method for preparing aluminum polysulfate aluminum silicate using aluminum oxide and a silicon dioxide scavenging catalyst,

The present invention relates to a process for preparing aluminum polysulfate silicate using aluminum oxide and a silicon dioxide scavenging catalyst.

Aluminum oxide (Al ₂ O ₃ ) and silicon dioxide (SiO 2) catalysts (silica alumina catalysts) are a typical solid acid catalyst as a mixed catalyst of aluminum oxide and silicon dioxide and are most widely used as catalytic cracking catalysts for petroleum Catalyst.

Catalytic cracking, represented by FCC (Fluidized Catalytic Cracking), is a process mainly for the production of gasoline and light oil from reduced pressure diesel, heavy oil. Recently, FCC waste catalysts due to the increase of oil consumption have been increasing day by day. SK Corporation, LG Caltex Oil, and S-Oil are among the domestic refining companies that have catalytic cracking processes, and their catalytic cracking process produces about 40 tons of waste catalyst per day.

FCC waste catalysts have a low content of heavy metals (about 3,000 ~ 8,000ppm), and the problem of environmental pollution caused by the elution of heavy metals is not a serious problem. However, due to the shortage of landfills and the increase of landfill costs, , And research on the recycling of waste catalyst of FCC is very important.

As for the recycling of FCC waste catalysts, studies have been conducted on the use of zeolite, the use of building materials used in the garden, the use of building materials used in ceilings, the use of asphalt fillers, etc. However, only a small amount is recycled as a catalyst, It is used for low usage.

Since the main component of the FCC waste catalyst is composed of aluminum oxide and silicon dioxide, if it can be recycled, it is preferable not only in terms of economic profit creation through recycling of resources but also in minimizing pollution problem of industrial waste .

Meanwhile, the Ministry of Environment revised the sewage law in order to improve the quality of water in the public waters and prevent eutrophication. From 2012, the total allowance of sewage treatment effluent water was increased from 2.0ppm to 0.2ppm to 0.5ppm (see Table 1 of the Enforcement Regulations of the Sewerage Act). Accordingly, the sewage and wastewater treatment facilities dispose of sewage and wastewater by arranging various physical, chemical and biological unit processes and finally discharge the discharged water according to the legal total allowance of discharged water.

The total phosphorus of the effluent discharged from the sewage treatment plant is mainly precipitated and removed by a chemical coagulant such as aluminum sulfate, polychlorinated aluminum (PAC), and aluminum polysulfate. Of these, aluminum polysulfate is used as a polyelectrolytic polymer compound in which an anionic complex reacted with stabilized anionic active silicic acid and a cationic substance is reacted with an anionic active silicic acid. While the pH range is wide from 4 to 12, And has excellent decolorization and flocculation performance for minerals and free materials, and has no harmful organic or chlorine components. The aluminum polysulfate aluminum silicate can achieve the same flocculation performance with the use amount of 70% as compared with the other aluminum flocculant solution. Therefore, for the operator of the treatment plant, it is possible to reliably remove phosphorus Can be said to be a high value-added drug.

According to the results of analysis on the operation and management status of the public sewage treatment facilities provided by the Ministry of Environment in 2013, the total amount of coagulant used in sewage treatment was 176,089 tons / year, and the total amount used in the purchase of coagulants was about 82.6 billion won. In view of the cost of purchasing aluminum hydroxide, which accounts for 50% or more of the coagulant cost, it is necessary to develop a material capable of replacing aluminum hydroxide. In order to gradually reduce the proportion of the cost of purchasing the flocculant from the sewage treatment plant operation cost, a flocculant having a relatively small amount of use is required while maintaining the same flocculation performance.

The present invention discloses a process by which aluminum oxide and silicon dioxide spent catalyst can be recycled in the production of aluminum polysulfate under such technical background.

It is an object of the present invention to provide a process for producing aluminum polysulfosilicate using aluminum oxide and a silicon dioxide scavenging catalyst.

Other and further objects of the present invention will be described below.

The present inventors have found that when aluminum aluminum silicate is produced by reacting aluminum oxide, a silicon dioxide scavenging catalyst and a sulfuric acid solution generated in a FCC (Fluid Catalytic Cracking) process, as shown in the following examples, Aluminum silicate satisfies the water treatment agent standard for aluminum polysulfate in the "Standard, Specification and Marking Standards for Water Treatment Chemicals" of the Ministry of Environment Notification No. 2008-69, and also satisfies the water flocculant standards of aluminum sulfate, aluminum polychloride, It was confirmed that aluminum was similar or higher than aluminum.

The present invention provides a process for producing aluminum polysulfosilicate using aluminum oxide and a silicon dioxide scavenging catalyst, comprising the steps of: (a) preparing aluminum oxide and a silicon dioxide scavenging catalyst; and (b) ) Reacting the spent catalyst with sulfuric acid.

In the present invention, the reaction formula in which aluminum oxide and silicon dioxide spent catalyst react with sulfuric acid to produce aluminum polysulfate aluminum silicate is as follows.

Al ₂ O ₃ + SiO ₂ + 2H ₂ SO ₄ ? Al ₂ (OH) ₂ (SO ₄ ) ₂ (SiO ₂ ) ₁ + H ₂ O

In the method of the present invention, the aluminum oxide and the silicon dioxide spent catalyst may be used as the aluminum oxide and the silicon dioxide catalyst after being used in the FCC process or the like, as long as the catalyst function is degraded and discarded. The spent catalyst contains aluminum oxide and silicon dioxide as its main components in the constitution of the component, and includes trace amounts of impurities such as vanadium (V) and nickel (Ni) adsorbed and accumulated during use as a catalyst. Specifically, the spent catalyst is an aluminum oxide and a silicon dioxide in an amount of 80% (w / w) or more, preferably 90% (w / w) or more, of aluminum oxide and silicon dioxide in a weight ratio of 8: 2 to 2: ) Or more, more preferably 95% (w / w) or more, and a trace amount of impurities such as heavy metals.

The waste catalyst may be recovered in the form of powder or granules. When recovered in powder form, the waste catalyst can be used as it is without any additional processing. However, if the granular catalyst is recovered in granular form or recovered in powder form, It is preferable to use a powder having a particle size of 106 탆 or less. If the particle size is larger than 106 탆, it is difficult to sufficiently react with the sulfuric acid solution, and the resulting aluminum polysulfate aluminum silicate also has a low solubility in water. The pulverization may be carried out by employing any pulverizing method known in the art such as wet pulverization or dry pulverization.

When impurities such as an organic substance are contained in the waste catalyst, it is preferable to remove impurities through pretreatment such as ignition treatment at a temperature of 500 ° C or more for 15 minutes or longer. The organic material also acts as an obstacle in the reaction with the sulfuric acid solution, which may lower the yield of the aluminum polysulfate aluminum silicate and increase the turbidity of the produced aluminum polysulfate aluminum silicate, which may interfere with its use as a coagulant.

In step (b) of the present invention, water is used as a reaction solvent, water is first injected into the spent catalyst, sulfuric acid solution is injected while stirring, and then, And reacting the catalyst with a sulfuric acid solution. In this case, it is preferable to inject the water so that the final purity of the sulfuric acid solution is 50% (v / v) in order to smoothly mix with the raw material and increase the reactivity. In order to reduce the transportation cost and utilize the hydration heat generated when the sulfuric acid and water are mixed It is preferable to use a sulfuric acid solution having a concentration of 70 to 79% (w / v). The mixing molar ratio of the aluminum dioxide and silicon dioxide in the spent catalyst and the sulfuric acid as the reactant is 1: 1: 2 : Silicon dioxide: sulfuric acid).

The reaction between the spent catalyst and the sulfuric acid is preferably at least 30 minutes at a temperature of 150 ° C or higher and 4 atmospheres or higher as described above. If the reaction temperature, pressure, and reaction time are lower than the above- The concentration of aluminum oxide (Al ₂ O ₃ ) is lowered, and thus the possibility of producing polysulfuric aluminum silicate having a low purity is high. On the other hand, if the reaction temperature, pressure and reaction time are kept too high or longer than the above- , The concentration of aluminum oxide (Al ₂ O ₃ ) in the aluminum polysulfate aluminum silicate becomes too high, and the possibility of solidification in the reaction tank is high. Therefore, it is preferable to maintain the reaction step within a range not greatly departing from the above-mentioned operating conditions provided by the present invention.

The method of the present invention may further comprise the step of adjusting the aluminum polysilicate aluminum silicate (Al ₂ O ₃ ) concentration to be at least 8% after step (b). These adjustment steps are based on the "Standard, Specification and Labeling Standards for Water Treatment Chemicals" of the Ministry of the Environment Notice 2008-69, which set the aluminum oxide content to 8% or more on the basis of aluminum polysulfate aluminum silicate (see Table 1 below). ) To meet these specification standards, this adjustment step can be achieved by diluting the reactants by adding water when the aluminum oxide (Al ₂ O ₃ ) concentration in the aluminum polysulfate is high. In this case, when the aluminum oxide (Al ₂ O ₃ ) concentration in the aluminum polysulfate aluminum silicate is increased to 8.5% or more, it is preferable to inject a stabilizer such as starch to prevent solidification.

In the method of the present invention, a step of allowing the reactant obtained in the step (b) to stand after the step (b) may be added. Since the unreacted spent catalyst is floating after the step (b), the quality of the aluminum polysulfate aluminum silicate is defined as "transparent liquid " Standards ". In order to meet this property criterion, it is preferable to recover the supernatant in the presence of aluminum polysulfate by precipitating the unreacted suspended spent catalyst through the settling step. At this time, the temperature may be adjusted until the supernatant liquid becomes clear, and it may be generally 10 to 20 hours, preferably 10 to 15 hours.

As described above, according to the method of the present invention, by using the aluminum oxide and the silicon dioxide scavenging catalyst, it is possible to manufacture at a cost lower than the production cost of the currently used commercial coagulant, satisfy the water treatment agent standard notified by the Ministry of Environment, It is possible to produce aluminum polysulfate aluminosilicate exhibiting cohesive performance.

In addition, the present invention has the effect of reducing the cost of treating waste catalysts such as landfill by recycling waste catalysts

Fig. 1 shows the result of the comparative evaluation of cohesion performance with a commercially available coagulant, aluminum sulfate.

Hereinafter, embodiments of the present invention will be described. However, the scope of the present invention is not limited to these embodiments.

≪ Example 1 & gt ; Manufacture of aluminum polysulfate silicate

In this embodiment, the aluminum oxide and silicon dioxide spent catalysts are waste catalysts generated in the FCC (Fluid Catalytic Cracking) process of an oil refinery of S company, Ulsan Metropolitan City. Atomic analysis was performed to determine the contents of aluminum and silicon, and the constituents of the spent catalyst were identified as shown in Table 1 below. The atomic analysis confirmed that the spent catalyst used in this example was mainly composed of aluminum oxide and silicon dioxide.

Since the waste catalyst is generated in powder form, a separate pretreatment process for injecting the raw material is omitted. The waste catalyst was injected into the reactor, water was injected, and 70 ~ 99% (v / v) sulfuric acid solution was injected while stirring. At this time, the amount of water to be injected was adjusted from the beginning so that the final concentration of the sulfuric acid solution was 50% (v / v). The reaction was continued for 30 minutes while maintaining the reaction temperature at 150 ° C or higher and the pressure at 4 atm or higher to induce the production of aluminum polysulfate silicate. Thereafter, dilute water was injected into the reaction tank to adjust the aluminum oxide (Al ₂ O ₃ ) content to be at least 8%, and the mixture was allowed to stand at room temperature for 12 hours to precipitate unreacted spent catalyst. The supernatant liquid was taken, Aluminum.

≪ Example 2 > Analysis of conformity with water treatment agent

The aluminum polyphosphoric acid silicate produced in Example 1 was submitted to a public institution (Korea Construction & Living Environment Test Research Institute), and the aluminum polyphosphoric acid aluminum silicate on the " Standards, Specification and Labeling Standards for Water Treatment Chemicals " And whether they meet the criteria for water treatment.

As a result of the analysis, as shown in Table 2, it was confirmed that the aluminum polysulfate manufactured in Example 1 was satisfactory for all items of the water treatment agent standard.

≪ Example 3 > Comparative evaluation of flocculation performance with a commercially available coagulant, aluminum sulfate

The coagulation performance of the aluminum polysulfate aluminum silicate prepared in Example 1 and the conventional coagulant was evaluated. The wastewater samples used synthetic wastewater with K ₂ HPO ₄ of 1.12 g per 20 L to effectively identify the phosphorus removal performance of aerobic sludge of the K City sewage treatment plant. The comparative evaluation commercial aluminum sulfate solution as the coagulant for the (Alum, aluminum oxide (Al ₂ O ₃₎ content 7.47%) was used.

Comparative evaluation is then the waste water sample of aluminum sulfate as shown in Table 3 below for the solution or the poly sulfate aluminum silicate solution after each injection rapidly as 120RPM 3 minutes and slow stirred for 30 minutes at 40RPM, was for 30 minutes PO ₄ -P concentration was measured (Jar-test), and the results are shown in Table 3 and FIG. 1 below.

As shown in Table 3, the <Example 1> The poly PO higher even when the aluminum silicate sulfate infusion for about 70% of 0.51mg / L of 0.73mg / L compared to the aluminum sulphate dosage commercial flocculants prepared from ₄ - P removal rate and the same Sludge Volume Index (SVI) value. It can be concluded that the polysulfuric aluminum silicate produced by this method has a lower injection amount and higher flocculation performance than commercial aluminum sulfate.

Example 4 Comparative Evaluation of Cohesion Performance of Polyphosphoric Acid Aluminum Silicate as a Coagulant for Commercial Use and Poly Aluminum Chloride

Next, comparative evaluation with the same aluminum polysulfate aluminum silicate (PASS) and aluminum polychloride (PAC) was conducted as another commercial flocculant. The wastewater samples used synthetic wastewater with K ₂ HPO ₄ of 1.12 g per 20 L to effectively identify the phosphorus removal performance of aerobic sludge of the K City sewage treatment plant. Table 4 shows the results for the same Al / P molar ratio.

As shown in Table 4, the aluminum polysulfate produced in Example 1 had similar flocculation performance and sedimentation performance as aluminum polysulfate (PASS), which is commonly used. Higher coagulation performance and sedimentation performance were confirmed.

Claims (5)

(a) preparing aluminum oxide and a silicon dioxide spent catalyst, and (b) reacting the spent catalyst with sulfuric acid, and (c) removing unreacted spent catalyst.
A method for producing a coagulant for removing phosphorus during water treatment comprising aluminum polysulfate and aluminum silicate using aluminum oxide and silicon dioxide scavenging catalyst.
The method according to claim 1,
Wherein the waste catalyst is prepared in the form of a powder having a particle size of 106 mu m or less.

The method according to claim 1,
Wherein the step (b) comprises injecting sulfuric acid solution with stirring and water, and then reacting the spent catalyst with the sulfuric acid solution for at least 30 minutes at a temperature of 150 ° C or more and 4 atm or more. Gt;
The method according to claim 1,
Wherein the step (b) further comprises the step of adjusting the concentration of aluminum oxide (Al ₂ O ₃ ) in aluminum polysulfate aluminum silicate to be at least 8%.
The method according to claim 1,
Wherein the step (b) is followed by the step of allowing the reactant obtained in the step (b) to stand.

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