CN109317208B - Preparation method of nitrate nitrogen denitrification catalyst - Google Patents

Preparation method of nitrate nitrogen denitrification catalyst Download PDF

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CN109317208B
CN109317208B CN201710642458.0A CN201710642458A CN109317208B CN 109317208 B CN109317208 B CN 109317208B CN 201710642458 A CN201710642458 A CN 201710642458A CN 109317208 B CN109317208 B CN 109317208B
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nitrate nitrogen
catalyst
preparing
polystyrene resin
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CN109317208A (en
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李波
潘咸峰
刘婷婷
黄斌
吕军
杜毅
解洪梅
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China Petroleum and Chemical Corp
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
    • B01J31/16—Catalysts comprising hydrides, coordination complexes or organic compounds containing coordination complexes
    • B01J31/165—Polymer immobilised coordination complexes, e.g. organometallic complexes
    • B01J31/1658—Polymer immobilised coordination complexes, e.g. organometallic complexes immobilised by covalent linkages, i.e. pendant complexes with optional linking groups, e.g. on Wang or Merrifield resins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/56—Platinum group metals
    • B01J23/63—Platinum group metals with rare earths or actinides
    • B01J35/615—
    • B01J35/617—
    • B01J35/635—
    • B01J35/638—
    • B01J35/647—
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0201—Impregnation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/34—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation
    • B01J37/341—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation making use of electric or magnetic fields, wave energy or particle radiation
    • B01J37/343—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation making use of electric or magnetic fields, wave energy or particle radiation of ultrasonic wave energy
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/70—Treatment of water, waste water, or sewage by reduction
    • C02F1/705—Reduction by metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2531/00—Additional information regarding catalytic systems classified in B01J31/00
    • B01J2531/10—Complexes comprising metals of Group I (IA or IB) as the central metal
    • B01J2531/16—Copper
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2531/00—Additional information regarding catalytic systems classified in B01J31/00
    • B01J2531/30—Complexes comprising metals of Group III (IIIA or IIIB) as the central metal
    • B01J2531/38—Lanthanides other than lanthanum
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2531/00—Additional information regarding catalytic systems classified in B01J31/00
    • B01J2531/80—Complexes comprising metals of Group VIII as the central metal
    • B01J2531/82—Metals of the platinum group
    • B01J2531/824—Palladium
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/16—Nitrogen compounds, e.g. ammonia
    • C02F2101/163—Nitrates

Abstract

A preparation method of a nitrate nitrogen denitrification catalyst, belonging to the field of sewage treatment. The method is characterized in that: the preparation steps are as follows: carrying out multi-part activation pretreatment on a macroporous polystyrene resin carrier; preparing the composite catalyst in one step; preparation of PdCl2And Ce (NO)3）3Primary immersion liquid; then carrying out ultrasonic treatment; adding citric acid and tri-n-butyl citrate, and then adding copper acetate for dissolving; preparing a steeping liquor; putting the carrier into the dipping solution for dipping and complexing; then soaking in the mixed solution of sodium hydroxide and hydrazine hydrate to obtain the catalyst. The commonly used two-step preparation method is improved into a one-step preparation method, the activity and the nitrogen selectivity of the catalyst are not reduced, and the preparation process is simple, scientific and reasonable. The metal ions are reduced to form metal clusters which are deeply sunk in the three-dimensional network structure of the resin, so that the activity is uniformly dispersed on the resin and is firmly combined.

Description

Preparation method of nitrate nitrogen denitrification catalyst
Technical Field
A preparation method of a nitrate nitrogen denitrification catalyst, belonging to the field of sewage treatment.
Background
The nitrogen element in the water body is mainly ionic nitrogen, wherein nitrate nitrogen is taken as the main component, and ammonia nitrogen and nitrite nitrogen are taken as the secondary components, the salts can cause pollution to the environment, the ammonia nitrogen can cause eutrophication of the water body, and the nitrite nitrogen can cause harm to the health of human bodies, animals and plants. The nitrate source in nature mainly comprises two aspects, namely wide waste water source and complex components, such as chemical fertilizer manufacturing, steel production, gunpowder manufacturing, feed production, meat processing, electronic components, flue gas denitration absorption liquid and the like, and part of nitrate can be reduced into nitrite after being taken into human bodies and animal bodies. Nitrite can oxidize hemoglobin in blood into ferrohemoglobin which does not have the capability of combining oxygen, and when the content of the ferrohemoglobin in the blood is increased, the capability of oxygen delivery of the blood is reduced, and serious patients cause human tissue purple plague, which is clinically called as methemoglobinemia. In addition, nitrite ions can cause baby blueness after entering a human body, and particularly, baby reaction within 4 months is sensitive, and the nitrite ions are easy to cause great harm to pregnant women, old and weak sensitive people. Nitrite can react with paraammonium in stomach to form strong carcinogen nitrosamine, and British, Chile and Columbia have reports of correlation between nitrate and high incidence rate of gastric cancer; a relationship between high nitrate levels in drinking water and the incidence of hypertension is found in the united states. According to rough statistics, about 3000 thousands of people in China drink high-nitrate saline water, and nitrate pollution becomes one of the main environmental factors for cancer occurrence in China. Therefore, the national relevant standards specify the concentration of nitrate in water, wherein the drinking water health standard specifies the maximum allowable concentration of nitrate to be 20mg/L, and the surface water quality standard GB3838-2002 specifies the maximum allowable concentration of nitrate in the surface water source of the centralized domestic drinking water to be 10 mg/L. In conclusion, how to effectively treat the high-concentration nitrate wastewater and improve the quality of the effluent water becomes one of the hot spots and difficulties in the field of water pollution control, and has been widely regarded by many researchers.
The method for treating the nitrate wastewater mainly comprises a physical-chemical method, a biological denitrification method and a catalytic reduction method. The method for removing nitrate in wastewater by a physical and chemical method mainly comprises an ion exchange method, reverse osmosis, electrodialysis, a steaming house method and the like. These processes are too costly to operate, they concentrate the nitrates in the medium or waste liquid, and do not actually remove them completely, but rather transfer or concentration of the nitrate contaminants takes place.
Biological denitrification is divided into two processes of nitrification and denitrification, and NH is generated by nitrification reaction4 +The nitrate is converted into nitrate, and denitrification refers to that denitrifying bacteria take the nitrate as an electron acceptor and reduce the nitrate into nitrogen to be released into the atmosphere under the condition of oxygen deficiency or oxygen-free.
The chemical catalytic reduction of nitrate refers to the reduction of nitrate into nitrogen by using hydrogen, formic acid and the like as reducing agents, adding a proper catalyst in the reaction and utilizing the catalytic action of the catalyst. The process has the advantages that the reaction activity is high and is 30 times higher than that of biological denitrification, and the key point of the process is to prepare the catalyst with good performance, so that the catalyst has high reaction activity and high selectivity.
There is a prior art activated carbon cloth supported bimetallic Pd-Cu nanocatalyst comprising about 1 wt% Pd and about 0.35 wt% to about 0.45 wt% Cu and having a thickness of about 8 to about 10m2/m2Surface Cu/Pd metal ratio of (a). The nanocatalyst is capable of removing nitrate and/or nitrite from wastewater with high selectivity to nitrogen. The preparation method of the catalyst is sputtering deposition, continuous hydrogen flow and nitrogen flow are required to be kept for high-temperature roasting reduction in the preparation process, the production process is difficult to control, and the prepared catalyst has low dispersity, so that the activity is poor and is only 77.6% at most.
Literature<<Experimental study on nitrate removal by chemical denitrification>>In a batch-wise complete mixing reactor with Pd-Cu/gamma-Al2O3The experimental research is carried out on the catalytic reduction of the nitrate as the catalyst, and the result shows that the nitrate can be effectively reduced to generate N under the action of the supported metal catalyst2The total nitrogen removal rate is up toMore than 80 percent. In the preparation process of the catalyst, the periodic stirring and room temperature drying time are longer. In addition, for the supported catalyst, the roasting at 350 ℃ is difficult to ensure the firm combination of the active component and the carrier, and the service life of the catalyst is easy to shorten.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: overcomes the defects of the prior art and provides a preparation method of the nitrate nitrogen removal catalyst with simple, scientific and reasonable preparation process.
The technical scheme adopted by the invention for solving the technical problems is as follows: the preparation method of the nitrate nitrogen denitrification catalyst is characterized by comprising the following steps: the preparation steps are as follows:
1) carrying out activation pretreatment on a macroporous polystyrene resin carrier;
2) preparing a composite catalyst;
2.1, mixing PdCl2And Ce (NO)3）3Dissolving in mixed aqueous solution of ethanol and citric acid to obtain PdCl2And Ce (NO)3）3Primary immersion liquid; then heating to 30-50 ℃ and carrying out ultrasonic treatment;
2.2, continuously adding citric acid and tri-n-butyl citrate, and then adding copper acetate for dissolving; then heating to 30-50 ℃ and carrying out ultrasonic treatment to prepare impregnation liquid;
2.3, placing the activated and pretreated macroporous polystyrene resin carrier in an impregnation liquid for impregnation for 4-8 hours to fully complex the macroporous polystyrene resin carrier; after the reaction is finished, separating the complex and drying the complex in a vacuum drying oven;
and 2.4, soaking the dried complex in a mixed solution of sodium hydroxide and hydrazine hydrate, reacting for 2-4 h, separating and drying to obtain the catalyst.
The invention also provides a preparation method of the nitrate nitrogen denitrification catalyst, which improves the commonly used two-step preparation method into a one-step preparation method, simultaneously does not reduce the activity and the nitrogen selectivity of the catalyst, and has simple, scientific and reasonable preparation process. The catalyst is applied to the process of catalytic reduction of nitrate nitrogen in sewage, the removal rate of the nitrate nitrogen is improved, and the selectivity of nitrogen is better.
Preferably, the activation pretreatment of the macroporous polystyrene resin carrier in the step 1) is specifically as follows:
1.1 adding macroporous polystyrene resin particles into a saturated calcium hydroxide solution, stirring at room temperature for 60-120 min, and washing the resin particles to be neutral;
1.2 adding the resin particles washed to be neutral in the step 1.1 into a methanol solution for stirring treatment at room temperature, wherein the stirring time is 60-120 min, and then washing;
1.3, soaking the resin washed in the step 1.2 in an EDTA saturated solution for 6-24 h, separating the resin, and drying to obtain the activated pretreated carrier.
The carrier is pretreated in multiple steps, so that the binding force of the carrier, EDTA (ethylene diamine tetraacetic acid) and active components is increased, a large amount of metal ions are bound and uniformly dispersed on the inner surface of micropores of the exchange resin, and the metal ions are reduced to form metal clusters which are deeply sunk in a three-dimensional network structure of the resin, so that the activity is uniformly dispersed on the resin and is firmly bound.
Preferably, the dipping time of the resin washed in the step 1.3 in the EDTA saturated solution is 9-13 h.
Preferably, the mass ratio of the saturated calcium hydroxide solution to the macroporous polystyrene resin is 100: 16-24, and the stirring time is 80-100 min. The preferable mass ratio can better pre-treat the carrier, so that the carrier and the active component are combined more firmly and stably.
Preferably, the mass ratio of the methanol solution to the macroporous polystyrene resin is 100: 16-24, and the stirring time is 80-100 min. The preferable mass ratio can better pre-treat the carrier, so that the carrier and the active component are combined more firmly and stably.
Preferably, the PdCl described in step 2.12And Ce (NO)3）3Mixed water solution of ethanol and citric acid in the primary immersion liquid, PdCl2And Ce (NO)3）3The mass ratio of (A) to (B) is 100: 1-4: 0.05-0.1, wherein the mass concentration of ethanol in the mixed aqueous solution is 20-30%, and the mass concentration of citric acid is 0.5-1%; the ultrasonic frequency of the ultrasonic treatment is10kHz-20kHz, and the treatment time is 1 min-5 min. In the preparation process of the catalyst, a low-power ultrasonic instrument is used for treating the mixed solution of the active components at a certain temperature, and the active components have good particle dispersibility in the solution under the double-layer action of outer-layer electronic space isomerization and ultrasonic dispersion. Preferred PdCl2The preparation method of the impregnation liquid can enable the Pd to be combined on the inner surfaces of the micropores of the exchange resin more uniformly and stably.
Preferably, the mass concentration of citric acid in the impregnation liquid in the step 2.2 is increased to 2-3%, the mass concentration of tri-n-butyl citrate is 0.01-0.05%, and the mass concentration of copper acetate is dissolved in a range of 2-8%; the ultrasonic frequency of the ultrasonic treatment is 10kHz-20kHz, and the treatment time is 1 min-5 min. The invention provides a new adding form of a Cu active component, which improves the commonly used two-step preparation method into a one-step preparation method, and simultaneously the activity and the nitrogen selectivity of the catalyst are not reduced.
Preferably, the macroporous polystyrene resin carrier subjected to activation pretreatment in the step 2.3 is soaked in the soaking solution for 5-6 hours.
Preferably, the mass concentration of the sodium hydroxide in the mixed solution of the sodium hydroxide and the hydrazine hydrate in the step 2.4 is 1-4%, and the mass concentration of the hydrazine hydrate is 2-3%. The optimal concentration can better promote the combination of the rest carriers of the active components, the combination is firmer, and the catalytic effect is stable for a longer period.
The prepared catalyst comprises an active component and a carrier, wherein the active component comprises the following components in percentage by mass: pd 1-1.5%, Cu 1-1.5%, Ce 0.03-0.05%; the carrier is macroporous polystyrene resin, and the specific surface of the macroporous polystyrene resin is 400 m2/g~600m2Per g, pore volume of 0.4 m3/g~2.0m3A pore diameter of 3.0 nm to 5.0 nm.
The catalyst is applied to the denitrification reaction of sewage, N2The selectivity is high, the content of total nitrogen in the sewage can be effectively reduced, the ammonia nitrogen in the sewage is ensured not to exceed the standard, and the national and local discharge indexes of the total nitrogen and the ammonia nitrogen in the sewage can be met.
Preferably, the content of the active component in the catalyst by mass percent further comprises: ce 0.035% -0.045%. The active component Ce is added in the preparation process of the catalyst, and the catalyst has obvious synergistic effect with the main active component, so that the removal rate of nitrate nitrogen reaches more than 94%, and the selectivity of nitrogen reaches more than 99%.
Preferably, the content of Pd in the catalyst is 1.1-1.3% by mass percent; the content of Cu in the catalyst is 1.2-1.3% by mass percent. The preferred active component content achieves the best nitrate chemical reduction catalytic effect of the catalyst.
Preferably, the specific surface area of the macroporous polystyrene resin is 500 m2/g～540m2G, pore volume of 1.4 m3/g～1.7m3(ii) in terms of/g. The physical property of the optimized macroporous polystyrene resin can load the active component with the optimal density, so that the catalytic effect is optimal, and the catalyst has longer stabilization time.
In the preparation process of the catalyst, a low-power ultrasonic instrument is used for treating the mixed solution of the active components at a certain temperature, and the active components have good particle dispersibility in the solution under the double-layer action of outer-layer electronic space isomerization and ultrasonic dispersion. The preferable preparation method of the copper sulfate impregnation liquid can enable Cu to be more uniformly and stably combined on the inner surfaces of the micropores of the exchange resin.
Compared with the prior art, the nitrate nitrogen denitrification catalyst and the preparation method thereof have the beneficial effects that:
1. the preparation process is simple, the commonly used two-step preparation method is improved into the one-step preparation method, and the activity and the nitrogen selectivity of the catalyst are not reduced.
2. The active components are highly effective and stable. The carrier is pretreated in multiple steps, so that the binding force of the carrier, EDTA (ethylene diamine tetraacetic acid) and active components is increased, a large amount of metal ions are bound and uniformly dispersed on the inner surface of micropores of the exchange resin, and the metal ions are reduced to form metal clusters which are deeply sunk in a three-dimensional network structure of the resin, so that the activity is uniformly dispersed on the resin and is firmly bound.
3. The removal rate of nitrate nitrogen and the selectivity of N2 are high. The catalyst is applied to the process of catalytic reduction of nitrate nitrogen in sewage, the removal rate of the nitrate nitrogen is more than 88%, and the selectivity of nitrogen reaches more than 90%.
Detailed Description
The present invention is further illustrated by the following specific examples, of which example 1 is the most preferred.
Example 1
Step one, putting 100ml of saturated calcium hydroxide solution and 20g of macroporous polystyrene resin particles into a flask with a stirrer, stirring at room temperature for 90min, and washing with deionized water until the washing water is neutral; adding the resin particles into 100ml of methanol solution, stirring at room temperature, stirring for 60min, and washing with deionized water for 3 times for later use. And (3) preparing an EDTA saturated solution, soaking the pretreated resin in the EDTA saturated solution for 6 hours, taking out the resin carrier, and drying in vacuum at room temperature.
Step two, taking 2.5g of PdCl2And 0.07gCe (NO 3)3Dissolving in 100g of mixed solution of ethanol, water and citric acid, wherein the concentration of ethanol in the mixed solution is 25%, the concentration of citric acid in the mixed solution is 0.7%, and the balance is water. Heating the mixed solution to 40 ℃, and then carrying out ultrasonic treatment by using a low-power ultrasonic instrument, wherein the frequency of ultrasonic reaction is 15kHz, and the time of ultrasonic reaction is 1 min. Adding citric acid and tri-n-butyl citrate into the solution after ultrasonic treatment, increasing the concentration of the citric acid to 2.5 percent, controlling the concentration of the tri-n-butyl citrate to be 0.03 percent, and adding copper acetate to dissolve until the mass concentration is 5 percent; heating the mixed solution to 40 ℃, and then carrying out ultrasonic treatment by using a low-power ultrasonic instrument, wherein the ultrasonic reaction frequency is 15kHz, and the ultrasonic reaction time is 1 min. And (3) soaking the pretreated resin carrier in the mixed solution after ultrasonic treatment for 5.5h, taking out, and drying in a vacuum drying oven. And (2) soaking the dried catalyst precursor in a mixed solution of sodium hydroxide and hydrazine hydrate, wherein the concentration of the sodium hydroxide in the solution is 2.5 percent, the concentration of the hydrazine hydrate is 2.5 percent, separating the catalyst precursor after 3 hours of soaking, and drying the catalyst precursor in vacuum at room temperature for later use.
The content of active components in the prepared catalyst in percentage by mass in the catalyst is as follows: pd1.25%, Cu 1.25%, Ce 0.04%; proportion table of macroporous polystyrene resinThe surface is 500 m2/g~580m2Per g, pore volume of 0.9 m3/g~1.7m3A pore diameter of 3.0 nm to 5.0 nm.
The prepared catalyst is applied to the effluent of a certain acrylonitrile catalytic oxidation device, the nitrate nitrogen of the water is 266mg/L, the pH is =6.3, and the main process operating conditions are as follows: h2The flow rate is 50ml/min, the pH value of inlet water is adjusted to 5.0, the volume of the reactor is 200ml, the adding amount of the catalyst is 0.15g, and the reaction time is 90 min. After treatment, the effluent is 25mg/L of nitrate nitrogen, the ammonia nitrogen is 15mg/L, the removal rate of the nitrate nitrogen in the reaction is 90.6%, and the selectivity of the nitrogen is 93.8%.
Example 2
Step one, putting 100ml of saturated calcium hydroxide solution and 18g of macroporous polystyrene resin particles into a flask with a stirrer, stirring at room temperature for 80min, and washing with deionized water until the washing water is neutral; adding the resin particles into 100ml of methanol solution, stirring at room temperature, stirring for 80min, and washing with deionized water for 3 times for later use. And (3) preparing an EDTA saturated solution, soaking the pretreated resin in the EDTA saturated solution for 24 hours, taking out the resin carrier, and drying in vacuum at room temperature.
Step two, taking 2gPdCl2And 0.08gCe (NO)3）3Dissolving in 100g of mixed solution of ethanol, water and citric acid, wherein the concentration of ethanol in the mixed solution is 27%, the concentration of citric acid in the mixed solution is 0.8%, and the balance is water. Heating the mixed solution to 35 ℃, performing ultrasonic treatment by using a low-power ultrasonic instrument, wherein the frequency of ultrasonic reaction is 17kHz, the ultrasonic reaction time is 3min, adding citric acid and tri-n-butyl citrate into the ultrasonic treated solution, increasing the concentration of the citric acid to 2.3%, the concentration of the tri-n-butyl citrate to 0.04%, and adding copper acetate to dissolve until the mass concentration is 3.5%; after the mixed solution is heated to 35 ℃, a low-power ultrasonic instrument is adopted for carrying out ultrasonic reaction, the frequency of the ultrasonic reaction is 15kHz, and the time of the ultrasonic reaction is 2 min. And (3) soaking the pretreated resin carrier in the mixed solution for 6 hours, then taking out, and drying in a vacuum drying oven. Soaking the dried catalyst precursor in a mixed solution of sodium hydroxide and hydrazine hydrate, wherein the concentration of the sodium hydroxide in the solution is 2 percent, and the concentration of the hydrazine hydrate in the solution is 2.7 percent, separating the catalyst after soaking for 3.5 hoursSeparating the precursor, and drying in vacuum at room temperature to obtain the catalyst;
the content of active components in the prepared catalyst in percentage by mass in the catalyst is as follows: pd1.1%, Cu 1.2%, Ce 0.035%; the specific surface area of the macroporous polystyrene resin is 470 m2/g~520m2Per g, pore volume of 0.7 m3/g~1.3m3(ii)/g, the pore diameter is 3.0 nm to 5.0 nm;
the prepared catalyst was applied to the effluent of a catalyst plant unit with a nitrate nitrogen of 644mg/L and pH = 7.18. The main process operating conditions are as follows: h2The flow rate is 50ml/min, the pH value of inlet water is adjusted to 5.0, the volume of the reactor is 200ml, the adding amount of the catalyst is 0.15g, and the reaction time is 120 min. After treatment, the effluent is 29.7mg/L of nitrate nitrogen, the ammonia nitrogen is 9mg/L, the removal rate of the nitrate nitrogen in the reaction is 94%, and the selectivity of the nitrogen is 99%.
Example 3
Step one, putting 100ml of saturated calcium hydroxide solution and 22g of macroporous polystyrene resin particles into a flask with a stirrer, stirring at room temperature for 90min, and washing with deionized water until the washing water is neutral; adding the resin particles into 100ml of methanol solution, stirring at room temperature, stirring for 60min, and washing with deionized water for 3 times for later use. And (3) preparing an EDTA saturated solution, soaking the pretreated resin in the EDTA saturated solution for 6 hours, taking out the resin carrier, and drying in vacuum at room temperature.
Step two, taking 3gPdCl2And 0.09gCe (NO)3）3Dissolving in 100g of mixed solution of ethanol, water and citric acid, wherein the concentration of ethanol in the mixed solution is 23%, the concentration of citric acid in the mixed solution is 0.6%, and the balance is water. Heating the mixed solution to 45 ℃, and then carrying out ultrasonic treatment by using a low-power ultrasonic instrument, wherein the ultrasonic reaction frequency is 12kHz, and the ultrasonic reaction time is 3 min. Adding citric acid and tri-n-butyl citrate into the solution after ultrasonic treatment, increasing the concentration of the citric acid to 2.7 percent, controlling the concentration of the tri-n-butyl citrate to 0.02 percent, and adding copper acetate to dissolve until the mass concentration is 6.5 percent; heating the mixed solution to 45 ℃, and then carrying out ultrasonic treatment by using a low-power ultrasonic instrument, wherein the ultrasonic reaction frequency is 12kHz, and the ultrasonic reaction time is 3 min. Subjecting the pretreated resin carrier to sonicationAnd soaking the mixed solution for 5h, taking out, and drying in a vacuum drying oven. Soaking the dried catalyst precursor in a mixed solution of sodium hydroxide and hydrazine hydrate, wherein the concentration of the sodium hydroxide in the solution is 3 percent, the concentration of the hydrazine hydrate is 2.3 percent, separating the catalyst precursor after soaking for 2.5 hours, and drying the catalyst precursor in vacuum at room temperature for later use;
the content of active components in the prepared catalyst in percentage by mass in the catalyst is as follows: pd1.3%, Cu 1.3%, Ce 0.047%; the specific surface area of the macroporous polystyrene resin is 520 m2/g~590m2Per g, pore volume of 0.6m3/g~1.5m3(ii)/g, the pore diameter is 3.0 nm to 5.0 nm;
the prepared catalyst is applied to the effluent of a certain acrylonitrile catalytic oxidation device, the nitrate nitrogen of the water is 266mg/L, the pH is =6.3, and the main process operating conditions are as follows: h2The flow is 50ml/min, the pH value of inlet water is adjusted to 5.0, the volume of the reactor is 200ml, the adding amount of the catalyst is 0.15g, and the reaction time is 90 min; after treatment, the effluent is 49.5mg/L of nitrate nitrogen, the ammonia nitrogen is 15mg/L, the removal rate of the reaction nitrate nitrogen is 92%, and the selectivity of nitrogen is 98.3%.
Example 4
Step one, putting 100ml of saturated calcium hydroxide solution and 16g of macroporous polystyrene resin particles into a flask with a stirrer, stirring at room temperature for 60min, and washing with deionized water until the washing water is neutral; adding the resin particles into 100ml of methanol solution, stirring at room temperature, stirring for 60min, and washing with deionized water for 3 times for later use. Preparing an EDTA saturated solution, soaking the pretreated resin in the EDTA saturated solution for 6 hours, taking out the resin carrier, and drying in vacuum at room temperature;
step two, taking 1gPdCl2And 0.1gCe (NO)3）3Dissolving in 100g of mixed solution of ethanol, water and citric acid, wherein the concentration of ethanol in the mixed solution is 20%, the concentration of citric acid in the mixed solution is 1%, and the balance is water. After the mixed solution is heated to 30 ℃, a low-power ultrasonic instrument is adopted for carrying out ultrasonic reaction, the frequency of the ultrasonic reaction is 20kHz, and the time of the ultrasonic reaction is 5 min. Adding citric acid and tri-n-butyl citrate into the solution after ultrasonic treatment, increasing the concentration of citric acid to 3%, and adding the tri-n-butyl citrateThe concentration is 0.01 percent, and copper acetate is added to dissolve until the mass concentration is 2 percent; after the mixed solution is heated to 30 ℃, a low-power ultrasonic instrument is adopted for carrying out ultrasonic reaction, the frequency of the ultrasonic reaction is 20kHz, and the time of the ultrasonic reaction is 5 min. And (3) soaking the pretreated resin carrier in the mixed solution after ultrasonic treatment for 4 hours, taking out, and drying in a vacuum drying oven. Soaking the dried catalyst precursor in a mixed solution of sodium hydroxide and hydrazine hydrate, wherein the concentration of the sodium hydroxide in the solution is 1 percent, the concentration of the hydrazine hydrate is 3 percent, separating the catalyst precursor after soaking for 2 hours, and drying the catalyst precursor in vacuum at room temperature for later use;
the content of active components in the prepared catalyst in percentage by mass in the catalyst is as follows: pd1%, Cu 1%, Ce 0.05%; the specific surface area of the macroporous polystyrene resin is 400 m2/g~500m2Per g, pore volume of 0.4 m3/g~1.0m3(ii)/g, the pore diameter is 3.0 nm to 5.0 nm;
the prepared catalyst is applied to the effluent of a certain acrylonitrile catalytic oxidation device, the nitrate nitrogen of the water is 266mg/L, the pH is =6.3, and the main process operating conditions are as follows: h2The flow is 50ml/min, the pH value of inlet water is adjusted to 5.0, the volume of the reactor is 200ml, the adding amount of the catalyst is 0.15g, and the reaction time is 90 min; after treatment, the effluent is 70.68mg/L of nitrate nitrogen, the ammonia nitrogen is 14mg/L, the removal rate of the nitrate nitrogen in the reaction is 88.6 percent, and the selectivity of the nitrogen is 97.1 percent.
Example 5
Step one, putting 100ml of saturated calcium hydroxide solution and 24g of macroporous polystyrene resin particles into a flask with a stirrer, stirring at room temperature for 120min, and washing with deionized water until the washing water is neutral; adding the resin particles into 100ml of methanol solution, stirring at room temperature, stirring for 120min, and washing with deionized water for 3 times for later use. Preparing an EDTA saturated solution, soaking the pretreated resin in the EDTA saturated solution for 6 hours, taking out the resin carrier, and drying in vacuum at room temperature;
step two, taking 4gPdCl2And 0.05gCe (NO)3）3Dissolving in 100g of mixed solution of ethanol, water and citric acid, wherein the concentration of ethanol in the mixed solution is 30%, the concentration of citric acid in the mixed solution is 1%, and the balance is water. The mixed solution is raisedAnd (3) after the temperature is 50 ℃, carrying out ultrasonic treatment by using a low-power ultrasonic instrument, wherein the ultrasonic reaction frequency is 10kHz, and the ultrasonic reaction time is 3 min. Adding citric acid and tri-n-butyl citrate into the solution after ultrasonic treatment, increasing the concentration of the citric acid to 2 percent, controlling the concentration of the tri-n-butyl citrate to be 0.05 percent, and adding copper acetate to dissolve until the mass concentration is 8 percent; heating the mixed solution to 50 ℃, and then carrying out ultrasonic treatment by using a low-power ultrasonic instrument, wherein the ultrasonic reaction frequency is 10kHz, and the ultrasonic reaction time is 3 min. And (3) soaking the pretreated resin carrier in the mixed solution after ultrasonic treatment for 8 hours, taking out, and drying in a vacuum drying oven. Soaking the dried catalyst precursor in a mixed solution of sodium hydroxide and hydrazine hydrate, wherein the concentration of the sodium hydroxide in the solution is 4 percent, the concentration of the hydrazine hydrate is 2 percent, separating the catalyst precursor after soaking for 4 hours, and drying the catalyst precursor in vacuum at room temperature for later use;
the content of active components in the prepared catalyst in percentage by mass in the catalyst is as follows: pd1.5%, Cu 1.5%, Ce 0.03%; the specific surface area of the macroporous polystyrene resin is 510 m2/g~600m2Per g, pore volume of 0.9 m3/g~2.0m3(ii)/g, the pore diameter is 3.0 nm to 5.0 nm;
the prepared catalyst is applied to the effluent of a certain acrylonitrile catalytic oxidation device, the nitrate nitrogen of the water is 266mg/L, the pH is =6.3, and the main process operating conditions are as follows: h2The flow is 50ml/min, the pH value of inlet water is adjusted to 5.0, the volume of the reactor is 200ml, the adding amount of the catalyst is 0.15g, and the reaction time is 90 min; after treatment, the effluent is 61.3mg/L of nitrate nitrogen, the ammonia nitrogen is 11mg/L, the removal rate of the nitrate nitrogen in the reaction is 88.4 percent, and the selectivity of the nitrogen is 97.1 percent.
Comparative example 1:
step one, putting 100ml of saturated sodium hydroxide solution and 20g of macroporous polystyrene resin particles into a flask with a stirrer, stirring at room temperature for 60min, and washing with deionized water until the washing water is neutral; adding the resin particles into 100ml of methanol solution, stirring at room temperature, stirring for 60min, and washing with deionized water for 3 times for later use. And (3) preparing an EDTA saturated solution, soaking the pretreated resin in the EDTA saturated solution for 6 hours, taking out the resin carrier, and drying in vacuum at room temperature.
Step two is the same as step two of example 1.
The prepared catalyst is applied to the effluent of a certain acrylonitrile catalytic oxidation device, the nitrate nitrogen of the water is 266mg/L, the pH is =6.3, and the main process operating conditions are as follows: h2The flow rate is 50ml/min, the pH value of inlet water is adjusted to 5.0, the volume of the reactor is 200ml, the adding amount of the catalyst is 0.15g, and the reaction time is 90 min. After treatment, the effluent is 65mg/L of nitrate nitrogen, the ammonia nitrogen is 43mg/L, the removal rate of the nitrate nitrogen in the reaction is 75.5%, and the selectivity of the nitrogen is 78.6%.
Comparative example 2:
taking gamma-Al2O3200ml of the carrier is soaked in EDTA with the same volume for 30min, then vacuum drying is carried out at 100 ℃, and after being taken out, 1% palladium chloride mixed solution (the concentration of ethanol in the mixed solution is 23%, the concentration of citric acid is 0.5%, and the balance is water) is added. Heating the mixed solution to 40 ℃, and then carrying out ultrasonic treatment by using a low-power ultrasonic instrument, wherein the ultrasonic reaction frequency is 10kHz, and the ultrasonic reaction time is 1 min. Citric acid and tri-n-butyl citrate were added to the solution after sonication, the citric acid concentration was increased to 3% and the tri-n-butyl citrate concentration was 0.01%, and 4g of copper acetate was added for dissolution. Heating the mixed solution to 30 ℃, performing ultrasonic treatment by using a low-power ultrasonic instrument, keeping the dipping time for 90min after the ultrasonic reaction frequency is 10kHz and the ultrasonic reaction time is 1min, drying the mixed solution in a vacuum drying oven at 100 ℃ after the dipping is finished, and roasting the mixed solution in a muffle furnace at 450 ℃ for 2 h. After the baking is finished, the reaction product is cooled to room temperature, reduced by hydrazine hydrate, washed by deionized water and dried.
The prepared catalyst is applied to the effluent of a certain acrylonitrile catalytic oxidation device, the nitrate nitrogen of the water is 266mg/L, the pH is =6.3, and the main process operating conditions are as follows: h2The flow rate is 50ml/min, the pH value of inlet water is adjusted to 5.0, the volume of the reactor is 200ml, the adding amount of the catalyst is 0.15g, and the reaction time is 90 min. After treatment, the effluent is 41mg/L of nitrate nitrogen, the ammonia nitrogen is 57mg/L, the removal rate of the reaction nitrate nitrogen is 84.6%, and the selectivity of nitrogen is 74.5%.
The foregoing is directed to preferred embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the protection scope of the technical solution of the present invention.

Claims (10)

1. A preparation method of a nitrate nitrogen denitrification catalyst is characterized by comprising the following preparation steps:
1) carrying out activation pretreatment on a macroporous polystyrene resin carrier;
2) preparing a composite catalyst;
2.1, mixing PdCl2And Ce (NO)3）3Dissolving in mixed aqueous solution of ethanol and citric acid to obtain PdCl2And Ce (NO)3）3Primary immersion liquid; then heating to 30-50 ℃ and carrying out ultrasonic treatment;
2.2, continuously adding citric acid and tri-n-butyl citrate, and then adding copper acetate for dissolving; then heating to 30-50 ℃ and carrying out ultrasonic treatment to prepare impregnation liquid;
2.3, placing the activated and pretreated macroporous polystyrene resin carrier in an impregnation liquid for impregnation for 4-8 hours to fully complex the macroporous polystyrene resin carrier; after the reaction is finished, separating the complex and drying the complex in a vacuum drying oven;
and 2.4, soaking the dried complex in a mixed solution of sodium hydroxide and hydrazine hydrate, reacting for 2-4 h, separating and drying to obtain the catalyst.
2. The method for preparing a nitrate nitrogen removal catalyst according to claim 1, characterized in that: the activation pretreatment of the macroporous polystyrene resin carrier in the step 1) specifically comprises the following steps:
1.1 adding macroporous polystyrene resin particles into a saturated calcium hydroxide solution, stirring at room temperature for 60-120 min, and washing the resin particles to be neutral;
1.2 adding the resin particles washed to be neutral in the step 1.1 into a methanol solution for stirring treatment at room temperature, stirring for 60-120 min and then washing;
1.3, soaking the resin washed in the step 1.2 in an EDTA saturated solution for 6-24 h, separating the resin, and drying to obtain the activated pretreated carrier.
3. The method for preparing a nitrate nitrogen removal catalyst according to claim 2, characterized in that: and (3) soaking the washed resin in the EDTA saturated solution for 9-13 h.
4. The method for preparing a nitrate nitrogen removal catalyst according to claim 2, characterized in that: the mass ratio of the saturated calcium hydroxide solution to the macroporous polystyrene resin is 100: 16-24, and the stirring time is 80-100 min.
5. The method for preparing a nitrate nitrogen removal catalyst according to claim 2, characterized in that: the mass ratio of the methanol solution to the macroporous polystyrene resin is 100: 16-24, and the stirring time is 80-100 min.
6. The method for preparing a nitrate nitrogen removal catalyst according to claim 1, characterized in that: PdCl as described in step 2.12And Ce (NO)3）3Mixed water solution of ethanol and citric acid in the primary immersion liquid, PdCl2And Ce (NO)3）3The mass ratio of (A) to (B) is 100: 1-4: 0.05-0.1, wherein the mass concentration of ethanol in the mixed aqueous solution is 20-30%, and the mass concentration of citric acid is 0.5-1%; the ultrasonic frequency of the ultrasonic treatment is 10kHz-20kHz, and the treatment time is 1 min-5 min.
7. The method for preparing a nitrate nitrogen removal catalyst according to claim 1, characterized in that: the mass concentration of citric acid in the impregnation liquid in the step 2.2 is increased to 2% -3%, the mass concentration of tri-n-butyl citrate is 0.01% -0.05%, and the mass concentration of copper acetate is 2% -8%; the ultrasonic frequency of the ultrasonic treatment is 10kHz-20kHz, and the treatment time is 1 min-5 min.
8. The method for preparing a nitrate nitrogen removal catalyst according to claim 1, characterized in that: and (3) soaking the macroporous polystyrene resin carrier subjected to activation pretreatment in the step 2.3 in the soaking solution for 5-6 hours.
9. The method for preparing a nitrate nitrogen removal catalyst according to claim 1, characterized in that: in the step 2.4, the mass concentration of the sodium hydroxide in the mixed solution of the sodium hydroxide and the hydrazine hydrate is 1-4%, and the mass concentration of the hydrazine hydrate is 2-3%.
10. The method for preparing a nitrate nitrogen removal catalyst according to claim 1, characterized in that: the prepared catalyst comprises an active component and a carrier, wherein the active component comprises the following components in percentage by mass: pd 1-1.5%, Cu 1-1.5%, Ce 0.03-0.05%; the carrier is macroporous polystyrene resin, and the specific surface area of the macroporous polystyrene resin is 400 m2/g~600m2Per g, pore volume of 0.4 m3/g~2.0m3A pore diameter of 3.0 nm to 5.0 nm.
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