CN109574188B

CN109574188B - Wet oxidation treatment method for formaldehyde-containing wastewater

Info

Publication number: CN109574188B
Application number: CN201710895371.4A
Authority: CN
Inventors: 陈航宁; 郭宗英; 郑育元; 许丹丹; 吴粮华
Original assignee: China Petroleum and Chemical Corp; Sinopec Shanghai Research Institute of Petrochemical Technology
Current assignee: China Petroleum and Chemical Corp; Sinopec Shanghai Research Institute of Petrochemical Technology
Priority date: 2017-09-28
Filing date: 2017-09-28
Publication date: 2021-10-01
Anticipated expiration: 2037-09-28
Also published as: CN109574188A

Abstract

The invention relates to a wet oxidation treatment method of formaldehyde-containing wastewater. The method is used for solving the problem of low efficiency of reducing the aldehyde content in the wastewater in the prior method. The invention relates to a method for treating formaldehyde-containing wastewater by wet oxidation, which comprises the following steps of reacting the wastewater with an oxidant containing oxygen in a reactor in the presence of a wet oxidation heterogeneous catalyst, wherein the wet oxidation heterogeneous catalyst comprises the following components in parts by weight: (1) 90-99.5 parts of a catalyst carrier; (2) the technical scheme of 0.1-5 parts of at least one precious metal selected from platinum group better solves the problem and can be used for quickly degrading high-concentration formaldehyde in wastewater.

Description

Wet oxidation treatment method for formaldehyde-containing wastewater

Technical Field

The invention relates to a wet oxidation treatment method of formaldehyde-containing wastewater, in particular to a wet oxidation treatment method of industrial acrylic acid wastewater.

Technical Field

Formaldehyde is high in toxicity, is the second place on the toxic chemical list in China, is determined as a teratogenic and mutagenic substance by the world health organization and the United states environmental protection agency, and is determined as a carcinogenic substance by the world cancer society. Because it can cause large-area death of biological strains, if the water contains high-concentration formaldehyde, the biochemical difficulty is extremely high. Catalytic wet oxidation is a platform technology for treating high-concentration organic wastewater.The method is characterized in that organic wastewater is oxidized into CO in a liquid phase under the conditions of high temperature (125-320 ℃) and high pressure (0.5-20 MPa) by taking air or pure oxygen as an oxidant under the action of a catalyst₂And inorganic substances such as water or small molecular organic substances. The process is an environment-friendly, energy-saving and environment-friendly organic wastewater treatment method, and is very suitable for treating high-concentration organic wastewater.

The invention discloses an organic wastewater treatment process, which comprises the following steps: materialization pretreatment, anaerobic hydrolysis acidification treatment and TCBS system treatment. The invention can improve the biodegradability of organic wastewater, enhance the toxicity resistance and impact resistance of a system, strengthen the biological denitrification function of the system, and enable the organic wastewater to meet the national environmental protection requirements by reducing pollution load step by step. But the method is only suitable for treating the low-concentration formaldehyde wastewater.

CN101553436 discloses an apparatus for treating high concentration organic wastewater and a method for treating organic wastewater using the same. An apparatus for treating high concentration organic wastewater includes a carrier reactor that receives organic wastewater to be treated and oxidatively decomposes organic materials included in the organic wastewater using aerobic microorganisms attached to carriers. However, this method is not suitable for treating organic waste water containing biological toxicity.

CN1030983 discloses a method for treating phenolic aldehyde-containing wastewater by using a photocatalytic method. In the invention, in phenolic aldehyde-containing wastewater, 10-15 ml of concentrated HCl per liter is polymerized for 5 hours at the temperature of 80-90 ℃, phenolic resin is recovered, and then TiO is added into the phenolic resin-removed wastewater₂，MnO₂And heating the catalyst to 60 ℃, stirring, introducing air, and degrading under illumination to ensure that the phenol is discharged at 0.5-1 mg/liter, but the treatment efficiency of the photocatalysis method is low.

Disclosure of Invention

The invention aims to solve the technical problem that the COD removal efficiency of a wet oxidation catalyst in the prior art is low, and provides a novel wet oxidation treatment method for high-concentration organic wastewater, which has the advantage of high COD removal efficiency.

In order to solve the technical problems, the technical scheme of the invention is as follows:

a wet oxidation treatment method of formaldehyde-containing wastewater comprises the step of reacting the wastewater with an oxidant containing oxygen in a reactor in the presence of a wet oxidation heterogeneous catalyst to remove formaldehyde in the wastewater, wherein the wet oxidation heterogeneous catalyst comprises the following components in parts by weight:

(1) 90-99.5 parts of a catalyst carrier;

(2)0.1 to 5 parts of at least one noble metal selected from platinum group.

In the above technical solution, the oxidant is preferably air or oxygen.

In the technical scheme, the reaction temperature is preferably 120-200 ℃.

In the technical scheme, the reaction pressure is preferably 2-5 MPa.

In the technical scheme, the preferable residence time of the wastewater is 5-60 minutes.

In the above technical solution, the catalyst carrier is preferably selected from TiO₂、ZrO₂、SiO₂And Al₂O₃One kind of (1).

In the above technical solution, the noble metal is preferably at least one selected from Ru, Pd, Pt, Ir, and Rh.

In the technical scheme, the catalyst has a comparable effect on organic wastewater with any concentration, but has a more obvious advantage on the treatment of the organic wastewater with high concentration. The COD value of the formaldehyde-containing wastewater is preferably 10,000-200,000 mg/L.

In the above technical solution, the catalyst preferably further comprises (3) 0.1-5 parts of a co-catalyst, wherein the co-catalyst is selected from at least one of copper and tin. The noble metal and the cocatalyst have obvious synergistic effect in the aspect of formaldehyde removal effect.

In the technical scheme, the cocatalyst preferably comprises copper and tin at the same time, and the copper and the tin have obvious synergistic effect in the aspect of removing formaldehyde in the organic wastewater. In this case, the weight ratio of copper to tin is not particularly limited, but is, for example, not limited to, 0.1 to 10, and more specific non-limiting weight ratios within this ratio range may be 0.21, 0.41, 0.61, 0.81, 1.01, 1.51, 2.01, 2.51, 3.01, 3.51, 4.01, 4.51, 5.01, 5.51, 6.1, 8.1, and the like.

In the above technology, the wet oxidation heterogeneous catalyst can be prepared by a preparation method comprising the following steps:

1) mixing a compound solution containing a noble metal element with a carrier;

2) reducing the combined-state noble metal introduced in the step 1) into a simple substance.

In the above technical solution, when the catalyst contains a promoter, the preparation method may further be a first method comprising the following steps:

(1) mixing an aqueous mixture solution containing a noble metal and a compound containing a promoter with a carrier;

(2) reducing the noble metal and the cocatalyst in a combined state into simple substances.

In the above technical solution, when the catalyst contains a promoter, the preparation method may further be a second method comprising the following steps:

1) mixing a solution of a compound containing a noble metal element with a carrier;

2) roasting to obtain a catalyst precursor I;

3) mixing a compound solution containing a promoter element with a precursor I;

4) reducing the introduced compound metal into simple substance.

In the above technical solution, when the catalyst contains a promoter, the preparation method may further be a third method comprising the following steps:

(i) mixing a compound aqueous solution containing a cocatalyst with a carrier, drying and roasting to obtain a catalyst precursor I;

(ii) mixing an aqueous solution containing a noble metal compound with a catalyst precursor I;

(iii) (iii) reducing the combined noble metal introduced in step (ii) to elemental form.

Compared with the three methods, the method has a surprisingly good technical effect on removing formaldehyde when the catalyst prepared by the method three is adopted.

In the above technical scheme, the specific method of reduction is not particularly limited as long as the active component in a combined state can be reduced to a simple substance. For example, the precursor may be reduced in the gas phase with a gaseous reducing agent, or may be reduced in the liquid phase with a solution of a reducing agent or a liquid phase reducing agent. Gaseous reducing agents commonly used may include hydrogen gas, such as hydrogen gas, hydrogen-nitrogen mixtures, and the like. The reducing agent for liquid phase reduction may be hydrazine hydrate, formic acid or sodium formate, etc.

In the above technical scheme, the compound containing tin element is preferably selected from any one of tin oxalate, tin tetrachloride and stannous chloride.

In the above technical solution, the copper element-containing compound is preferably selected from any one of copper nitrate, copper chloride, copper sulfate and copper acetate.

In the above technical scheme, the compound of the noble metal active component is not particularly limited, such as but not limited to ruthenium trichloride, palladium chloride, chloropalladic acid, chloroplatinic acid, rhodium chloride, and the like.

In the technical scheme, the roasting process of the catalyst precursor I is carried out in an air atmosphere, the roasting temperature is preferably 300-600 ℃, and the roasting time is preferably 2-4.5 hours.

It is known to those skilled in the art that when hydrogen is used as the reducing agent for reduction, a hydrogen-nitrogen mixture having a hydrogen content of 5% by volume or less is preferred for safety.

In the technical scheme, when hydrogen is used for reduction, the reduction temperature is preferably 300-700 ℃, and is further preferably 350-600 ℃; the reduction time is preferably 1 to 5 hours, and more preferably 2.5 to 4.5 hours.

The technical key of the invention is the selection of the catalyst, and the source of the formaldehyde-containing wastewater is not particularly limited, such as but not limited to industrial acrylic acid wastewater.

By adopting the technical scheme, the result shows that the C-10 catalyst simultaneously containing platinum, tin and copper prepared by the method can effectively reduce high-concentration formaldehyde in the wastewater under the conditions of reaction temperature of 180 ℃, pressure of 4MPa and retention time of 30 minutes, and the removal rate of the formaldehyde can reach 99.9% after wet oxidation treatment, thereby obtaining better technical effect.

The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention in any way.

Detailed Description

[ example 1 ]

1. Catalyst preparation

Calculated by weight ratio, Al₂O₃Ru and Sn in a ratio of 97:1: 2.

97 parts of Al₂O₃The catalyst support was impregnated with RuCl equivalent to 1 part Ru at room temperature₃And 2 parts of Sn₄RuCl of₃-SnCl₄The resulting mixture was dried at 80 ℃ for 12 hours overnight in 100 parts of the mixed aqueous solution, and then reduced at 300 ℃ for 4 hours in a hydrogen atmosphere (a mixed gas of hydrogen and nitrogen having a hydrogen content of 4 v%) to obtain a catalyst. The catalyst formulation is shown in table 1.

2. Catalyst evaluation

The industrial acrylic acid wastewater is taken as a raw material, and the content of formaldehyde in the wastewater is 11082 mg/L. The wastewater was mixed with oxygen and passed through a 125mL fixed bed reactor packed with 120g of catalyst. The reaction temperature in the reactor was 180 ℃, the pressure 4MPa, and the residence time 30 minutes. The reaction results are shown in Table 2.

[ example 2 ]

1. Catalyst preparation

Calculated by weight ratio, Al₂O₃Pd and Sn are 97:1: 2.

97 parts of Al₂O₃The catalyst support was impregnated with PdCl equivalent to 1 part of Pd at room temperature₂And 2 parts of Sn₄PdCl of (2)₂-SnCl₄The resulting mixture was dried at 80 ℃ for 12 hours overnight in 100 parts of the mixed aqueous solution, and then reduced at 300 ℃ for 4 hours in a hydrogen atmosphere (a mixed gas of hydrogen and nitrogen having a hydrogen content of 4 v%) to obtain a catalyst. The catalyst formulation is shown in table 1.

2. Catalyst evaluation

[ example 3 ]

1. Catalyst preparation

Calculated by weight ratio, Al₂O₃Pt and Sn in a ratio of 97:1: 2.

97 parts of Al₂O₃The catalyst carrier was impregnated with H corresponding to 1 part of Pt at room temperature₂PtCl₆And 2 parts of Sn₄H of (A) to (B)₂PtCl₆-SnCl₄The resulting mixture was dried at 80 ℃ for 12 hours overnight in 100 parts of the mixed aqueous solution, and then reduced at 300 ℃ for 4 hours in a hydrogen atmosphere (a mixed gas of hydrogen and nitrogen having a hydrogen content of 4 v%) to obtain a catalyst. The catalyst formulation is shown in table 1.

2. Catalyst evaluation

[ example 4 ]

1. Catalyst preparation

Calculated by weight ratio, Al₂O₃Pt and Sn in a ratio of 97:1: 2.

97 parts of Al₂O₃The catalyst carrier was impregnated with H corresponding to 1 part of Pt at room temperature₂PtCl₆And (3) drying the aqueous solution at 80 ℃ for 12 hours overnight in 100 parts of the aqueous solution, and then roasting the aqueous solution for 4 hours in an air atmosphere at 400 ℃ to obtain a catalyst precursor B-04. B-04 was immersed in SnCl in an amount of 2 parts by weight of Sn₄After drying the aqueous solution at 80 ℃ for 12 hours overnight in 100 parts of the aqueous solution, the solution was reduced at 300 ℃ for 4 hours in a hydrogen atmosphere (hydrogen-nitrogen mixed gas having a hydrogen content of 4% by volume) to obtain a catalyst. The catalyst formulation is shown in table 1.

2. Catalyst evaluation

[ example 5 ]

1. Catalyst preparation

Calculated by weight ratio, Al₂O₃Pt and Sn in a ratio of 97:1: 2.

97 parts of Al₂O₃The catalyst carrier was impregnated with SnCl equivalent to 2 parts of Sn at room temperature₄And (3) drying the aqueous solution at 80 ℃ for 12 hours overnight in 100 parts of the aqueous solution, and then roasting the aqueous solution for 4 hours in an air atmosphere at 400 ℃ to obtain a catalyst precursor B-05. B-05 was immersed in H corresponding to 1 part of Pt₂PtCl₆After drying the aqueous solution at 80 ℃ for 12 hours overnight in 100 parts of the aqueous solution, the solution was reduced at 300 ℃ for 4 hours in a hydrogen atmosphere (hydrogen-nitrogen mixed gas having a hydrogen content of 4% by volume) to obtain a catalyst. The catalyst formulation is shown in table 1.

2. Catalyst evaluation

[ example 6 ]

1. Catalyst preparation

In terms of weight ratio, SiO₂Pt and Sn in a ratio of 97:1: 2.

97 parts of SiO₂The catalyst carrier was impregnated with SnCl equivalent to 2 parts of Sn at room temperature₄And (3) drying the aqueous solution at 80 ℃ for 12 hours overnight in 100 parts of the aqueous solution, and then roasting the aqueous solution for 4 hours at 400 ℃ in an air atmosphere to obtain a catalyst precursor B-06. B-06 was impregnated with H corresponding to 1 part of Pt₂PtCl₆After drying the aqueous solution at 80 ℃ for 12 hours overnight in 100 parts of the aqueous solution, the solution was reduced at 300 ℃ for 4 hours in a hydrogen atmosphere (hydrogen-nitrogen mixed gas having a hydrogen content of 4% by volume) to obtain a catalyst. The catalyst formulation is shown in table 1.

2. Catalyst evaluation

[ example 7 ]

In weight ratio, TiO₂Pt and Sn in a ratio of 97:1: 2.

97 parts of TiO₂The catalyst carrier was impregnated with SnCl equivalent to 2 parts of Sn at room temperature₄And (3) drying the aqueous solution at 80 ℃ for 12 hours overnight in 100 parts of the aqueous solution, and then roasting the aqueous solution for 4 hours in an air atmosphere at 400 ℃ to obtain a catalyst precursor B-07. B-07 was immersed in H corresponding to 1 part of Pt₂PtCl₆After drying the aqueous solution at 80 ℃ for 12 hours overnight in 100 parts of the aqueous solution, the solution was reduced at 300 ℃ for 4 hours in a hydrogen atmosphere (hydrogen-nitrogen mixed gas having a hydrogen content of 4% by volume) to obtain a catalyst. The catalyst formulation is shown in table 1.

2. Catalyst evaluation

[ example 8 ]

In weight ratio, ZrO₂Pt and Sn in a ratio of 97:1: 2.

97 parts of ZrO₂The catalyst carrier was impregnated with SnCl equivalent to 2 parts of Sn at room temperature₄And (3) drying the aqueous solution at 80 ℃ for 12 hours overnight in 100 parts of the aqueous solution, and then roasting the aqueous solution for 4 hours in an air atmosphere at 400 ℃ to obtain a catalyst precursor B-08. B-08 was impregnated with H corresponding to 1 part of Pt₂PtCl₆After drying the aqueous solution at 80 ℃ for 12 hours overnight in 100 parts of the aqueous solution, the solution was reduced at 300 ℃ for 4 hours in a hydrogen atmosphere (hydrogen-nitrogen mixed gas having a hydrogen content of 4% by volume) to obtain a catalyst. The catalyst formulation is shown in table 1.

2. Catalyst evaluation

[ example 9 ]

Calculated by weight ratio, Al₂O₃Pt and Cu in a ratio of 97:1: 2.

97 parts of Al₂O₃The catalyst carrier was impregnated with Cu (NO) equivalent to 2 parts of Cu at room temperature₃)₂And (3) drying the aqueous solution at 80 ℃ for 12 hours overnight in 100 parts of the aqueous solution, and then roasting the aqueous solution for 4 hours at 400 ℃ in an air atmosphere to obtain a catalyst precursor B-09. B-09 was immersed in H corresponding to 1 part of Pt₂PtCl₆The resulting mixture was dried at 80 ℃ for 12 hours overnight, and then reduced at 300 ℃ for 4 hours in a hydrogen atmosphere (hydrogen-nitrogen mixed gas having a hydrogen content of 4 v%) to obtain a catalyst. The catalyst formulation is shown in table 1.

2. Catalyst evaluation

[ example 10 ]

Calculated by weight ratio, Al₂O₃Pt, Cu, Sn, 97:1:1.2: 0.8.

97 parts of Al₂O₃The catalyst carrier was impregnated with SnCl equivalent to 0.8 part of Sn at room temperature₄And 1.2 parts of Cu (NO)₃)₂And (3) drying the aqueous solution at 80 ℃ for 12 hours overnight in 100 parts of the aqueous solution, and then roasting the aqueous solution for 4 hours in an air atmosphere at 400 ℃ to obtain a catalyst precursor B-10. B-10 was immersed in H corresponding to 1 part of Pt₂PtCl₆The solution was allowed to stand overnight in an aqueous solution, dried at 80 ℃ and then reduced at 300 ℃ for 4 hours in a hydrogen atmosphere (hydrogen-nitrogen mixed gas having a hydrogen content of 4 v%) to obtain a catalyst. The catalyst formulation is shown in table 1.

2. Catalyst evaluation

[ example 11 ]

1. Catalyst preparation

Calculated by weight ratio, Al₂O₃Pt 97:3 catalyst was prepared.

97 parts of Al₂O₃The catalyst carrier was impregnated with H equivalent to 3 parts of Pt at room temperature₂PtCl₆After drying the aqueous solution at 80 ℃ for 12 hours overnight in 100 parts of the aqueous solution, the solution was reduced at 300 ℃ for 4 hours in a hydrogen atmosphere (hydrogen-nitrogen mixed gas having a hydrogen content of 4% by volume) to obtain a catalyst. The catalyst formulation is shown in table 1.

2. Catalyst evaluation

[ example 12 ]

1. Catalyst preparation

Calculated by weight ratio, Al₂O₃Sn is 97: 3.

97 parts of Al₂O₃The catalyst carrier was impregnated with SnCl equivalent to 3 parts of Sn at room temperature₄After drying the aqueous solution at 80 ℃ for 12 hours overnight in 100 parts of the aqueous solution, the solution was reduced at 300 ℃ for 4 hours in a hydrogen atmosphere (hydrogen-nitrogen mixed gas having a hydrogen content of 4% by volume) to obtain a catalyst. The catalyst formulation is shown in table 1.

2. Catalyst evaluation

[ example 13 ]

1. Catalyst preparation

Calculated by weight ratio, Al₂O₃Cu 97:3 catalyst was prepared.

97 parts of Al₂O₃The catalyst carrier was impregnated with Cu (NO) equivalent to 3 parts of Cu at room temperature₃)₂The aqueous solution was dried at 80 ℃ overnight in 100 parts of an aqueous solution, and then reduced at 300 ℃ for 4 hours in a hydrogen atmosphere (hydrogen-nitrogen mixed gas having a hydrogen content of 4% by volume) to obtain a catalyst. The catalyst formulation is shown in table 1.

2. Catalyst evaluation

TABLE 1 formulation of the catalyst

Examples	Catalyst preparation method	Catalyst formulation	The mass ratio of each component
				Example 1	Method 1	Al₂O₃:Ru:Sn	97:1:2
Example 2	Method 1	Al₂O₃:Pd:Sn	97:1:2
				Example 3	Method 1	Al₂O₃:Pt:Sn	97:1:2
Example 4	Method two	Al₂O₃:Pt:Sn	97:1:2
				Example 5	Method III	Al₂O₃:Pt:Sn	97:1:2
Example 6	Method III	SiO₂Pt:Sn	97:1:2
				Example 7	Method III	TiO₂:Pt:Sn	97:1:2
Example 8	Method III	ZrO₂:Pt:Sn	97:1:2
				Example 9	Method III	Al₂O₃:Pt:Cu	97:1:2
Example 10	Method III	Al₂O₃:Pt:Cu:Sn	97:1:1.2:0.8
				Example 11	--	Al₂O₃:Pt	97:3
Example 12	--	Al₂O₃:Sn	97:3
				Example 13	--	Al₂O₃:Cu	97:3

TABLE 2 reaction results

Claims

1. A wet oxidation treatment method of formaldehyde-containing wastewater comprises the step of reacting the wastewater with an oxidant containing oxygen in a reactor in the presence of a wet oxidation heterogeneous catalyst to remove formaldehyde in the wastewater, wherein the wet oxidation heterogeneous catalyst comprises the following components in parts by weight:

(1) 90-99.5 parts of a catalyst carrier;

(2) 0.1-5 parts of at least one noble metal selected from platinum group;

the catalyst also comprises (3) 0.1-5 parts of a cocatalyst, wherein the cocatalyst is copper and tin, and the weight ratio of copper to tin is 1.5-10;

the reaction temperature is 120-180 ℃, and the reaction pressure is 2-4 MPa;

the wet oxidation heterogeneous catalyst is prepared by the following method: (i) mixing a compound aqueous solution containing a cocatalyst with a catalyst carrier, drying and roasting to obtain a catalyst precursor I; (ii) mixing an aqueous solution containing a noble metal compound with a catalyst precursor I; (iii) (iii) reducing the combined noble metal introduced in step (ii) to elemental form.

2. The wet oxidation treatment method as set forth in claim 1, wherein the oxidizing agent is air or oxygen.

3. The wet oxidation treatment method according to claim 1, wherein the retention time of the waste water is 5 to 60 minutes.

4. The wet oxidation treatment method according to claim 1, wherein the catalyst carrier is selected from the group consisting of TiO₂、ZrO₂、SiO₂And Al₂O₃One kind of (1).

5. The wet oxidation treatment method according to claim 1, wherein the noble metal is at least one member selected from the group consisting of Ru, Pd, Pt, Ir and Rh.

6. The wet oxidation treatment method according to claim 1, wherein the formaldehyde-containing wastewater has a formaldehyde content of 100 to 20,000 mg/L.