TWI623493B - Tmah solution decomposition apparatus - Google Patents

Abstract

The invention discloses a decomposition method of a tetramethylammonium hydroxide (TMAH) solution and a decomposition device thereof, which mainly achieve the purpose of decomposing tetramethylammonium hydroxide by mixing a tetramethylammonium hydroxide solution, an oxidant and a catalyst. The oxidizing agent includes primary chlorate or primary chlorate, and the tetramethylammonium hydroxide solution reacts with the oxidizing agent, and the catalyst adsorbs oxygen atoms generated during the reaction. The oxygen atoms adsorbed by the catalyst further participate in the reaction, thereby decomposing tetramethylammonium hydroxide into nitrogen and alcohol. The tetramethylammonium hydroxide removal rate in the tetramethylammonium hydroxide solution can be made greater than 99% by the decomposition method of the tetramethylammonium hydroxide solution proposed by the present invention.

Description

Decomposition device of tetramethylammonium hydroxide solution

The invention relates to a method for decomposing a tetramethylammonium hydroxide (TMAH) solution and a decomposition device thereof, which mainly comprises mixing a tetramethylammonium hydroxide solution, an oxidizing agent and a catalyst to generate nitrogen gas and an alcohol.

In the semiconductor process, tetramethyl ammonium hydroxide (TMAH) is often used to remove photoresist and produce wastewater containing tetramethylammonium hydroxide. Since tetramethylammonium hydroxide is toxic, wastewater cannot be directly discharged. It is common practice to use microorganisms or bleach to decompose tetramethylammonium hydroxide in wastewater and then discharge it. Microbial decomposition of tetramethylammonium hydroxide is slow and requires a large area of space to meet the needs of the current semiconductor industry.

The use of bleach to decompose tetramethylammonium hydroxide is generally carried out by adding the hypochlorous acid to the tetramethylammonium hydroxide wastewater by a fulcrum and chlorination method, and controlling the pH value between PH6 and PH7. To achieve the purpose of decomposing tetramethylammonium hydroxide. However, the chlorination method requires a large amount of hypochlorous acid, and the control of the pH range is difficult because of the continuous addition of hypochlorous acid during the reaction. In addition, after the reaction of tetramethylammonium hydroxide with hypochlorous acid chlorination, the action with water is reduced to the form of ammonia nitrogen, which greatly reduces the decomposition efficiency, and the decomposition efficiency is only about 5% to 10%.

An object of the present invention is to provide a method for decomposing a tetramethylammonium hydroxide solution, which mainly comprises mixing a tetramethylammonium hydroxide solution, an oxidizing agent and a catalyst, and adsorbing a tetramethylammonium hydroxide solution and an oxidizing agent by using a catalyst. The oxygen atoms produced after the reaction produce nitrogen and alcohol. By this method, the tetramethylammonium hydroxide removal rate in the tetramethylammonium hydroxide solution can be greater than 99%, and the concentration of tetramethylammonium hydroxide in the tetramethylammonium hydroxide wastewater produced by the semiconductor process can be obtained. It is reduced from below 4000 ppm to below 1 ppm.

Another object of the present invention is to apply a method for decomposing a tetramethylammonium hydroxide solution according to the present invention to a tetramethylammonium hydroxide solution decomposition apparatus. The tetramethylammonium hydroxide solution decomposition device mainly comprises a mixing tank, at least one transfer tube and a catalyst tank, wherein the mixing tank is connected to the catalyst tank through the transfer tube. The mixing tank is used for mixing the tetramethylammonium hydroxide solution and the oxidant, and generates N(CH3)3ClOH. The catalyst tank is used for accommodating a catalyst, and the N(CH3)3ClOH and the fourth are received from the mixing tank through the transfer tube. Water molecules in methylammonium hydroxide solution. The water molecules react with N(CH3)3ClOH to produce NH(CH3)3OH, while the catalyst adsorbs the oxygen atoms produced by the reaction of water molecules with N(CH3)3ClOH. NH(CH3)3OH, the oxygen atoms adsorbed by the catalyst, and water molecules react to produce nitrogen and alcohol. In addition, a tetramethylammonium hydroxide solution, N(CH3)3ClOH, NH(CH3)3OH, an oxidizing agent and/or a hydrochloric acid may flow between the mixing tank and the catalyst tank through a transfer pipe to achieve the effect of mixing and increase The efficiency of nitrogen and alcohol production.

In order to achieve the above object, the present invention provides a method for decomposing a tetramethylammonium hydroxide solution, comprising the steps of: mixing a tetramethylammonium hydroxide solution, an oxidizing agent and a catalyst, wherein The oxidizing agent includes primary chlorate or primary chlorate, and the catalyst adsorbs an oxygen atom generated by the reaction of the tetramethylammonium hydroxide solution with the oxidizing agent; and generates a nitrogen gas and an alcohol.

In order to achieve the above object, the present invention provides a decomposition apparatus for a tetramethylammonium hydroxide solution, comprising: a mixing tank for mixing a tetramethylammonium hydroxide solution and an oxidizing agent to produce a N(CH3)3ClOH, Wherein the tetramethylammonium hydroxide solution comprises monomethylammonium hydroxide and one water molecule, and the oxidant comprises primary chlorate or primary chlorate; at least one transfer tube is connected to the mixing tank; and a catalyst tank is used for Storing a catalyst and connecting the transfer tube, wherein the catalyst tank receives N(CH3)3ClOH and water molecules from the mixing tank through the transfer tube, so that the water molecules react with N(CH3)3ClOH to generate an NH(CH3)3OH, and The catalyst adsorbs an oxygen atom generated by the reaction of water molecules with N(CH3)3ClOH, and reacts NH(CH3)3OH, an oxygen atom adsorbed by the catalyst, and water molecules to produce a nitrogen gas and an alcohol.

In an embodiment of the decomposition method of the present invention, the tetramethylammonium hydroxide solution comprises monomethylammonium hydroxide and one water molecule.

In an embodiment of the decomposition method of the present invention, the method further comprises the steps of: mixing a tetramethylammonium hydroxide solution, an oxidizing agent and a catalyst to produce an NH(CH3)3OH; and an oxygen atom adsorbed by the catalyst, NH ( CH3) 3OH and water molecules react to produce nitrogen and alcohol.

In an embodiment of the decomposition method of the present invention, the method further comprises the steps of: mixing a tetramethylammonium hydroxide solution and an oxidizing agent to produce a N(CH3)3ClOH; adding a catalyst to cause a catalyst, N(CH3)3ClOH and water. The molecules are mixed and produce a NH(CH3)3OH, and the catalyst adsorbs the oxygen atoms generated by the reaction of N(CH3)3ClOH with water molecules; and the oxygen atoms, NH(CH3)3OH and water molecules adsorbed by the catalyst Nitrogen and alcohol are produced.

In an embodiment of the decomposition method of the present invention, the method further comprises the steps of: mixing a tetramethylammonium hydroxide solution, an oxidizing agent and a catalyst to produce a NH(CH3)3OH and a hydrochloric acid; and adding a base to make the alkali and the hydrochloric acid. Acid-base neutralization.

In an embodiment of the decomposition method of the present invention, wherein the base is sodium hydroxide.

In an embodiment of the decomposition method of the present invention, the catalyst comprises carbon or activated carbon.

In an embodiment of the decomposition method of the present invention, the catalyst is electrically conductive and does not chemically react with oxygen atoms generated after the reaction of the tetramethylammonium hydroxide solution with the oxidizing agent.

In an embodiment of the decomposition method of the present invention, the oxidizing agent is used in an amount of from 1 to 1.2 times the number of moles required.

In an embodiment of the decomposition method of the present invention, wherein the oxidizing agent comprises hypochlorous acid, sodium hypochlorite or calcium hypochlorite.

In an embodiment of the decomposition apparatus of the present invention, wherein N(CH3)3ClOH and the catalyst are contacted with water molecules, NH(CH3)3OH and monohydrochloric acid are produced.

In an embodiment of the decomposition apparatus of the present invention, the catalyst comprises carbon or activated carbon.

In an embodiment of the decomposition apparatus of the present invention, the mixing tank or the catalyst tank is further configured to receive a base and neutralize the acid and alkali to make the pH value in the mixing tank or the catalyst tank greater than PH7.

In an embodiment of the decomposition apparatus of the present invention, wherein the transfer tube forms a loop between the mixing tank and the catalyst tank, and the tetramethylammonium hydroxide solution, N(CH3)3ClOH, NH(CH3)3OH or the oxidant is transmitted. The tube flows between the mixing tank and the catalyst tank.

20‧‧‧Decomposition device for tetramethylammonium hydroxide solution

21‧‧‧ mixing tank

211‧‧‧ input

22‧‧‧catalyst slot

221‧‧‧Input tube

23‧‧‧ Catalyst

24‧‧‧Transmission tube

Fig. 1 is a flow chart showing the steps of an embodiment of the method for decomposing a tetramethylammonium hydroxide solution of the present invention.

Fig. 2 is a schematic view showing the structure of an embodiment of a decomposition apparatus for a tetramethylammonium hydroxide solution of the present invention.

While the invention has been described by way of illustrations in the drawings The drawings and the scope of the present invention are to be construed as being Modifications, equivalent components, and permutations thereof are within the scope of the invention.

Please refer to FIG. 1 , which is a flow chart showing the steps of an embodiment of a method for decomposing a tetramethylammonium hydroxide solution of the present invention. As shown, the decomposition method of the present invention may include steps S101 and S103. Mixing a tetramethylammonium hydroxide solution, an oxidizing agent, and a catalyst, wherein the oxidizing agent includes hypochlorite or hypochlorite, and the catalyst is used to adsorb oxygen atoms generated by reacting the tetramethylammonium hydroxide solution with the oxidizing agent, as in the step S101 is shown.

The tetramethylammonium hydroxide solution of the present invention comprises tetramethylammonium hydroxide (TMAH, N(CH3)4OH) and water molecules. In an embodiment of the invention, the tetramethylammonium hydroxide solution may be a wastewater containing tetramethylammonium hydroxide produced by a semiconductor process.

The catalyst according to the present invention may be one which is electrically conductive and does not chemically react with oxygen atoms generated after the reaction of the tetramethylammonium hydroxide solution with the oxidizing agent. In an embodiment of the invention, the catalyst comprises carbon or activated carbon, wherein the activated carbon is a preferred embodiment of the invention. Activated carbon has a large surface area, and its efficiency and quantity of adsorbing oxygen atoms are preferred, so the use of activated carbon can increase the reaction rate of the decomposition method of the present invention.

After the tetramethylammonium hydroxide solution, the oxidizing agent, and the catalyst are mixed, nitrogen gas and alcohol are generated as shown in step S103. Specifically, after the tetramethylammonium hydroxide solution, the oxidizing agent, and the catalyst are mixed, NH(CH3)3OH (trimethylammonium hydroxide) is generated, and the catalyst adsorbs oxygen atoms, such as tetramethyl hydroxide. The ammonium solution reacts with the oxidant to produce NH(CH3)3OH and an oxygen atom, and the catalyst adsorbs the oxygen atoms generated by the reaction of the tetramethylammonium hydroxide solution with the oxidant. The oxygen atoms adsorbed by the catalyst react with water molecules in NH(CH3)3OH and tetramethylammonium hydroxide solutions to produce nitrogen and alcohol, which will effectively decompose tetramethylammonium hydroxide.

In an embodiment of the present invention, the tetramethylammonium hydroxide solution and the oxidizing agent may be mixed first, and then the catalyst is added. Please refer to the following chemical chemical reaction formula: N(CH3)4OH+HOCl→N(CH3)3ClOH +CH3OH..........(1) N(CH3)3ClOH+H2O+C* → NH(CH3)3OH+HCl+C*O..........(2) 3C*O+2NH(CH3)3OH+H2O → N2+6CH3OH+3C*.... (3) For example, the tetramethylammonium hydroxide solution may be mixed with the oxidizing agent hypochlorous acid to make tetramethylammonium hydroxide (TMAH, N(CH3)4OH). It reacts with hypochlorous acid and produces N(CH3)3ClOH (monochlorotrimethylammonium hydroxide) as shown in the chemical reaction formula (1). Next, a catalyst is added to contact or mix the water molecules in the catalyst, N(CH3)3ClOH and tetramethylammonium hydroxide solution to produce NH(CH3)3OH (trimethylammonium hydroxide) and oxygen atoms. The catalyst adsorbs oxygen atoms. For example, N(CH3)3ClOH reacts with water molecules to produce NH(CH3)3OH and oxygen atoms, while the catalyst adsorbs oxygen atoms generated by the reaction of N(CH3)3ClOH with water molecules, such as chemistry. The reaction formula (2) is shown. then The oxygen atoms adsorbed by the catalyst will further react with NH(CH3)3OH and water molecules, and produce nitrogen and alcohols, as shown by the chemical reaction formula (3).

Chemical Reaction Formula (2) and Chemical Reaction Formula (3) C* represents a catalyst including carbon, and C*O represents a catalyst that adsorbs oxygen atoms, rather than carbon monoxide. Since the oxygen atoms themselves are not stable, in general, the two oxygen atoms combine to form oxygen (O2) to form a stable octahedral structure. In the present invention, a catalyst is used to adsorb oxygen atoms to prevent two oxygen atoms from being combined into oxygen, as shown by the chemical reaction formula (2). The oxygen atoms adsorbed by the catalyst can be further reacted with NH(CH3)3OH and water molecules to produce nitrogen gas and alcohols, as shown in the chemical reaction formula (3).

Although the chemical reaction formulas (2) and (3) are exemplified by a catalyst including carbon, this is not a limitation of the scope of the present invention, and in other embodiments of the present invention, as long as it is as described above, it is in conformity with conductivity. The catalyst which does not chemically react with the oxygen atom generated after the reaction of the tetramethylammonium hydroxide solution and the oxidizing agent can be used as the catalyst used in the present invention.

If a catalyst is not used, the oxygen atom bonded to oxygen will not participate in the reaction of the chemical reaction formula (3), in other words, the reaction described in the chemical reaction formula (3) will not occur. Please refer to the following chemical reaction formula without using catalyst: 2N(CH3)3ClOH+2H2O → 2NH(CH3)3OH+2HCl+O2..........(4)

NH(CH3)3OH+HOCl → NH(CH3)2ClOH+CH3OH..........(5)

2NH(CH3)2ClOH+2H2O → 2NH2(CH3)2OH+2HCl+O2..........(6)

NH2(CH3)2OH+HOCl → NH2(CH3)ClOH+CH3OH...(7)

2NH2(CH3)ClOH+2H2O → 2NH3(CH3)OH+2HCl+O2...(8)

For the convenience of the following description, NH(CH3)3OH (trimethylammonium hydroxide) and NH2(CH3)2OH (dimethylammonium hydroxide) in the above chemical reaction formulas (4) to (8) are used herein. And NH3(CH3)OH (methylammonium hydroxide) is commonly known as tetramethylammonium hydroxide derivative, and N(CH3)3ClOH (monochlorotrimethylhydroxide) in the chemical reaction formulas (4) to (8) Ammonium), NH(CH3)2ClOH (monochlorodimethylammonium hydroxide) and NH2(CH3)ClOH (monochloromethylammonium hydroxide) are commonly referred to as tetramethylammonium hydroxide chloride.

The reaction of the tetramethylammonium hydroxide derivative with the oxidant produces tetramethylammonium hydroxide chloride, as shown by the chemical reaction formulas (5) and (7), and the tetramethylammonium hydroxide chloride reacts with water. A tetramethylammonium hydroxide derivative and oxygen are produced as shown in the chemical reaction formulas (4), (6), and (8). In other words, the tetramethylammonium hydroxide solution cannot be decomposed into nitrogen and alcohol without using the catalyst of the present invention.

In an embodiment of the invention, the oxidizing agent is used in an amount of from 1 to 1.2 times the number of moles required. The equivalent number in the present invention means the number of moles of the oxidizing agent to be used for balancing the chemical reaction formulas (1), (2), and (3). Although hypochlorous acid is used as the oxidizing agent in the chemical reaction formula (1), hypochlorous acid is only one embodiment of the present invention and is not a limitation of the scope of the present invention. In other embodiments of the present invention, the oxidizing agent may be hypochlorite. An acid salt or other liquid including hypochlorite, such as sodium hypochlorite, calcium hypochlorite, sodium hypochlorite solution or calcium hypochlorite solution.

In one embodiment of the present invention, NH(CH3)3OH (trimethylammonium hydroxide) and hydrochloric acid are produced after mixing or contacting water molecules in a catalyst, N(CH3)3ClOH, and tetramethylammonium hydroxide solution. , as shown in the chemical reaction formula (2).

Since the decomposition method of the tetramethylammonium hydroxide solution of the present invention is carried out under a biased acid environment, a highly toxic Cl2 and/or Cl3 may be produced. For this purpose, in one embodiment of the present invention, a base may be added. For example, sodium hydroxide is used to neutralize the base with hydrochloric acid. In a preferred embodiment of the invention, sodium hydroxide can be used to adjust the pH to greater than pH 7 to avoid the production of Cl2 and/or Cl3.

Through the decomposition method of the tetramethylammonium hydroxide solution of the present invention, the removal rate of tetramethylammonium hydroxide in the tetramethylammonium hydroxide solution can be made 99% or more. Taking the tetramethylammonium hydroxide wastewater produced by the general semiconductor process as an example, the concentration of tetramethylammonium hydroxide in the wastewater is about 4,000 ppm or less, and the decomposition method of the tetramethylammonium hydroxide solution described in the present invention can be used. The concentration of tetramethylammonium hydroxide in the wastewater is reduced to less than 1 ppm, so the removal rate of tetramethylammonium hydroxide is 99.975% or more. Please refer to the following formula:

The method for decomposing the tetramethylammonium hydroxide solution of the present invention can be further applied to a decomposition apparatus of a tetramethylammonium hydroxide solution.

Please refer to FIG. 2, which is a schematic structural view of an embodiment of a decomposition apparatus for a tetramethylammonium hydroxide solution of the present invention. As shown, the decomposition apparatus 20 of the tetramethylammonium hydroxide solution includes a mixing tank 21, at least one transfer tube 24, and a catalyst tank 22, wherein the mixing tank 21 is connected to the catalyst tank 22 through the transfer tube 24.

The mixing tank 21 is used to mix a tetramethylammonium hydroxide solution including tetramethylammonium hydroxide and water molecules, and an oxidizing agent including hypochlorite or hypochlorite. Tetramethylammonium hydroxide in the tetramethylammonium hydroxide solution is mixed with the oxidizing agent in the mixing tank 21 to produce N(CH3)3ClOH (monochlorotrimethylammonium hydroxide).

The catalyst tank 22 is for accommodating a catalyst 23, and receives water molecules in the N(CH3)3ClOH and tetramethylammonium hydroxide solutions from the mixing tank 21 through the transfer tube 24, so that the water molecules and the N(CH3)3ClOH The reaction produces NH(CH3)3OH (monochlorotrimethylammonium hydroxide) and an oxygen atom, and the catalyst 23 adsorbs oxygen atoms generated by the reaction of water molecules with N(CH3)3ClOH, and The NH(CH3)3OH, the oxygen atom adsorbed by the catalyst 23, and the water molecules continue to react in the catalyst tank 22 to generate nitrogen gas and alcohol.

Of course, in practical use, N(CH3)3ClOH and water molecules in the mixing tank 21 may also react, and NH(CH3)3OH is formed in the mixing tank 21. For this purpose, the solution transported from the mixing tank 21 to the catalyst tank 22 may include an oxidizing agent, NH(CH3)3OH, and/or hydrochloric acid in addition to N(CH3)3ClOH and water molecules.

As described in the decomposition method of the tetramethylammonium hydroxide solution of the present invention, the catalyst 23 has electrical conductivity and does not chemically react with oxygen atoms generated after the reaction of the tetramethylammonium hydroxide solution with the oxidizing agent. In an embodiment of the invention, the catalyst 23 comprises carbon or activated carbon, wherein the activated carbon is a preferred embodiment of the invention, the activated carbon has a large surface area, and the efficiency and quantity of adsorbing oxygen atoms are better. Thus, the use of activated carbon can increase the reaction rate of the decomposition apparatus of the present invention.

Further, as described in the decomposition method of the tetramethylammonium hydroxide solution of the present invention, the oxidizing agent of the present invention may be hypochlorite or other liquid including hypochlorite, such as sodium hypochlorite or calcium hypochlorite. Sodium chlorate solution or calcium hypochlorite solution.

In an embodiment of the invention, the mixing tank 21 can include an input 211 for inputting a solution of tetramethylammonium hydroxide and an oxidizing agent.

In one embodiment of the invention, N(CH3)3ClOH reacts with water molecules to produce NH(CH3)3OH and hydrochloric acid. As described in the decomposition method of the tetramethylammonium hydroxide solution of the present invention, the decomposition reaction of the tetramethylammonium hydroxide solution is carried out under a biased acid environment, and a highly toxic Cl2 and/or Cl3 is produced. To this end, in an embodiment of the present invention, a base may be added to the mixing tank 21 and/or the catalyst tank 22, for example, the base may be added to the mixing tank 21 through the input end 211 of the mixing tank 21, or the catalyst tank 22 may further An input pipe 221 is included, and an alkali is added to the catalyst tank 22 through the input pipe 221 of the catalyst tank 22 to make a base. Neutralize with hydrochloric acid acid base. In a preferred embodiment of the present invention, sodium hydroxide may be added to the mixing tank 21 or the catalyst tank 22 to adjust the pH value of the mixing tank 21 and/or the catalyst tank 22 to be greater than PH7 to avoid Cl2. And / or the production of Cl3.

In an embodiment of the invention, the transfer tube 24 can form a loop between the mixing tank 21 and the catalyst tank 21, such that the tetramethylammonium hydroxide solution, N(CH3)3ClOH, NH(CH3)3OH or the oxidant is transported. The tube flows or circulates between the mixing tank 21 and the catalyst tank 22, so that the effect of mixing can be achieved to increase the production efficiency of nitrogen and alcohol.

Of course, in another embodiment of the decomposition apparatus of the tetramethylammonium hydroxide solution of the present invention, the catalyst tank 22 and the transfer tube 24 may not be included. The mixing tank 21 can also be used to accommodate the catalyst 23, and directly mix or contact the tetramethylammonium hydroxide solution, the oxidizing agent and the catalyst 23 by using the mixing tank 21, for example, through a stirrer (not shown) to make tetramethylhydrogen. The ammonium oxide solution, the oxidizing agent, and the catalyst 23 are mixed or contacted to produce nitrogen gas and alcohol.

The words "may," and "changes" as described in the specification are not limitations of the invention. The technical terms used in the specification are mainly for the description of specific embodiments and are not intended to be limiting. The single quantifiers (such as one and the one) used in the specification may also be plural, unless explicitly stated in the contents of the specification. For example, a device referred to in the specification may include a combination of two or more devices, and one of the materials mentioned in the specification may include a mixture of a plurality of substances.

The above is only the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, that is, the variations, modifications, and modifications of the shapes, structures, features, and spirits described in the claims of the present invention. All should be included in the scope of the patent application of the present invention.

Claims (4)

A decomposition device for a tetramethylammonium hydroxide solution, comprising: a mixing tank for mixing a tetramethylammonium hydroxide solution and an oxidizing agent to produce a N(CH3)3ClOH, wherein the tetramethylammonium hydroxide The solution comprises monomethylammonium hydroxide and one water molecule, and the oxidant comprises primary chlorate or primary chlorate, wherein the oxidant is used in an amount greater than 1 times the number of moles required and less than or equal to the required amount. 1.2 times the equivalent number, wherein the catalyst is electrically conductive and does not chemically react with the oxygen atom generated after the reaction of the tetramethylammonium hydroxide solution with the oxidizing agent; at least one transfer tube is connected to the mixing tank; And a catalyst tank for accommodating a catalyst and connecting the transmission tube, wherein the catalyst tank receives the N(CH3)3ClOH and the water molecule from the mixing tank through the transmission tube, so that the water molecule and The N(CH3)3ClOH reacts to produce a NH(CH3)3OH, and the catalyst adsorbs an oxygen atom generated by the reaction of the water molecule with the N(CH3)3ClOH, and the NH(CH3)3OH, the catalyst The adsorbed oxygen atom and the water molecule react to produce a nitrogen gas and an alcohol Wherein the transfer tube forms a loop between the mixing tank and the catalyst tank, and the tetramethylammonium hydroxide solution, the N(CH3)3ClOH, the NH(CH3)3OH or the oxidant is via the transfer tube The mixing tank and the catalyst tank flow between. The decomposition apparatus according to claim 1, wherein the N(CH3)3ClOH and the catalyst are contacted with the water molecule to produce the NH(CH3)3OH and monohydrochloric acid. The decomposition apparatus of claim 1, wherein the catalyst comprises carbon or activated carbon. The decomposition device of claim 3, wherein the mixing tank or the catalyst tank is further configured to receive a base and neutralize the hydrochloric acid acid to make the pH value in the mixing tank or the catalyst tank. Greater than PH7.