CN111167477A - Preparation method of cobalt-modified NO catalytic oxidant - Google Patents

Preparation method of cobalt-modified NO catalytic oxidant Download PDF

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CN111167477A
CN111167477A CN202010154263.3A CN202010154263A CN111167477A CN 111167477 A CN111167477 A CN 111167477A CN 202010154263 A CN202010154263 A CN 202010154263A CN 111167477 A CN111167477 A CN 111167477A
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catalyst
scr
temperature
catalytic
cobalt
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李坚
董逸雯
梁文俊
樊星
赵晶
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Beijing University of Technology
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Beijing University of Technology
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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
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/89—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals
    • B01J23/8933—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals also combined with metals, or metal oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/894—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals also combined with metals, or metal oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with rare earths or actinides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/8621—Removing nitrogen compounds
    • B01D53/8625—Nitrogen oxides
    • B01D53/8628—Processes characterised by a specific catalyst

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Abstract

A preparation method of a cobalt-modified NO catalytic oxidant belongs to the field of catalytic chemistry. The catalyst is prepared by the following steps: preparation of active component with RuO mass fraction by coprecipitation method2:0.5wt％、Co3O4:14‑25wt％、CeO2:49‑57wt％、ZrO224-29 wt% of viscous catalyst. The catalyst has good catalytic oxidation activity, sulfur resistance and water resistance, and the content of the sulfur is 700ppm NO and 5 vol% O2The carrier gas is N2The temperature is 250 ℃ and the space velocity is 30000h‑1Under the condition, the NO oxidation rate can reach 60 percent and is 200ppm SO2、5vol％H2O、700ppm NO、5vol％O2The carrier gas is N2The temperature is 250 ℃ and the space velocity is 30000h‑1Has oxidation activity of more than 35 percent for continuous 12 hours under the condition. And SCWhen the R catalyst is combined, the denitration performance of the SCR system at high airspeed can be improved, and a solid foundation is laid for the practical application of the rapid SCR technology of the ship.

Description

Preparation method of cobalt-modified NO catalytic oxidant
Technical Field
The invention designs a formula and a preparation method of a cobalt-modified NO catalytic oxidant, which convert part of NO into NO under the action of the catalytic oxidant2The volume ratio of NO to NO2 reaches 1:1 before the gas enters the SCR system, and when the SCR catalyst is combined, the denitration performance of the SCR system at high airspeed can be improved, the problem of limited space of a ship is solved, and the SCR catalyst belongs to the field of catalytic chemistry.
Background
Nitrogen Oxides (NO)x) Is one of the important pollutants in the atmosphere, and the sources can be divided into a mobile source and a fixed source. Among them, a ship is one of important moving sources. Aiming at more and more serious NO in ship tail gasxThe pollution problem of (2) is that a series of policy and regulations are established at home and abroad, and the emission standard of nitrogen oxides is increasingly strict. Currently, research on nitrogen oxide treatment technology has become a hot focus of society.
At present, nitrogen oxides in ship tail gas are mainly removed by a Selective Catalytic Reduction (SCR) method, but an SCR device is large, occupies a limited space of a ship and is difficult to arrange. Aiming at the requirements of the actual application of the ship SCR, the prepared catalyst has SO at low temperature and high airspeed2And H2It is important that the NO catalytic oxidant still has higher activity in the presence of O. Preparing NO catalytic oxidant with excellent performance, and aims at combining SCR catalyst to oxidize partial NO into NO2When NO and NO2When the volume ratio reaches 1:1, a rapid SCR reaction can occur under the action of the SCR catalyst. The reaction rate of the rapid SCR is about 10 times that of the standard SCR, so that the catalyst can keep better activity at high airspeed, thereby reducing the volume of the catalyst and solving the problem of narrow space of a ship.
After a great deal of research and experiment, Co is found out3O4Has excellent NO catalytic oxidation performance. And, Co3O4And RuO2、CeO2And ZrO2The NO catalytic oxidation performance and the sulfur-resistant and water-resistant performance of the synergistic multi-element metal oxide are more excellent. The addition of Co can block SO2At the active site of the catalystThe adsorption on the points improves the sulfur resistance of the catalyst. When there is H2Under the condition of O, nitrate is generated on the surface of the catalyst, and the decomposition temperature of the nitrate of Co is lower, so that the water resistance of the catalyst is improved.
At present, domestic research on the practical application aspect of NO catalytic oxidant is less, and SO is still difficult to achieve2And H2The catalyst still maintains higher catalytic oxidation activity under the condition of the existence of O. Aiming at the problem of the practical application of the rapid SCR, the invention ensures that the catalyst has better catalytic oxidation activity and sulfur resistance and water resistance at medium and low temperature.
Disclosure of Invention
The invention provides a preparation method of a cobalt-modified NO catalytic oxidant, which aims to improve the low-temperature activity of NO catalytic oxidation and the sulfur-resistant and water-resistant performance in practical application.
The technical scheme adopted by the invention is as follows:
the invention relates to a preparation method of a cobalt-modified NO catalytic oxidant, which comprises the following steps:
1) adding ruthenium trichloride solution, cobalt nitrate hexahydrate, cerium nitrate hexahydrate and zirconium nitrate pentahydrate into a proper amount of deionized water, and stirring and dissolving at the temperature of 60-80 ℃.
2) Adding NaOH solution with a certain concentration into the solution generated in the step 1), adjusting the pH value to 9-11, and stirring the solution at the temperature of 60-80 ℃ until the catalyst is sticky.
3) Centrifugally washing the sticky solid obtained in the step 2) for 1-5 times at the rotating speed of 3000-8000 r/min.
4) Putting the sticky solid obtained in the step 3) into an oven to be dried for 8-16h at 105 ℃.
5) And (3) putting the blocky solid obtained in the step 4) into a muffle furnace, roasting for 2-5h at 350-550 ℃, naturally cooling to room temperature, and screening to 20-40 meshes for later use.
Preferably: final active component Co of catalyst3O4:CeO2:ZrO2＝0:2:1-1.5:2:1，
Further preferably: the roasting temperature of the muffle furnace in the step 5) is 350 ℃.
The method for realizing rapid SCR by combining the NO catalytic oxidant and the SCR catalyst can oxidize part of NO in the flue gas into NO2NO before the gas enters the SCR system2The catalyst is approximately equal to 1:1, and the rapid SCR reaction is promoted to occur in the presence of an SCR catalyst, so that the reaction rate and the catalytic conversion rate of an SCR system are improved.
The invention has the following advantages:
at present, domestic research on sulfur resistance and water resistance of NO catalytic oxidant is few, and most of the existing NO catalytic oxidants can not have SO2And H2Certain activity is maintained under the condition of O existence. The invention provides a preparation method of a catalyst with good medium-low temperature activity and sulfur-resistant and water-resistant performance, wherein the SO content is 200ppm2、5vol％H2O、700ppm NO、5vol％O2The carrier gas is N2The temperature is 250 ℃ and the space velocity is 30000h-1Under the condition, the oxidation activity is still more than 35 percent after continuous 12 hours.
Compared with most of catalyst preparation methods, the preparation process of the catalyst is relatively simple and is suitable for industrial application.
When the catalyst is combined with the SCR catalyst, the denitration performance of an SCR system at high airspeed can be improved, and a solid foundation is laid for the practical application of the rapid SCR technology of the ship.
Drawings
FIG. 1 is a graph showing the catalytic oxidation efficiency of NO at different temperatures for catalysts No. 1, No. 2 and No. 3 obtained in examples 1, 2 and 3.
FIG. 2 is a graph showing the water resistance of catalysts No. 1, 2 and 3 obtained in examples 1, 2 and 3 at different temperatures.
FIG. 3 is a graph of the sulfur resistance of catalysts No. 1, 2 and 3 obtained in examples 1, 2 and 3 at different temperatures.
FIG. 4 is a graph showing the sulfur-resistant and water-resistant performance curves of catalysts # 1, # 2 and # 3 obtained in examples 1, 2 and 3 at different temperatures.
FIG. 5 is a graph of the sulfur resistance and water resistance of the # 2 catalyst obtained in example 2 at different temperatures.
Detailed Description
The present invention will be further described in conjunction with the following examples, but the present invention is not limited to the following examples.
Example 1:
25ml of RuCl with a concentration of 4g/L3·3H2O solution, 1.7179g Co (NO)3)2·6H2O，14.3438g Ce(NO3)2·6H2O and 9.9050g Zr (NO)3)2·5H2O is added to 100ml of deionized water and stirred in a water bath at 70 ℃ until completely dissolved. And adding 238ml of NaOH solution with the concentration of 1mol/L into the solution to adjust the pH value of the solution to 9-11, and stirring the solution under the condition of a water bath at 70 ℃ until the catalyst is viscous. The obtained sticky solid is centrifugally washed for 5 times at the rotating speed of 6000r/min and then is put into an oven to be dried for 12 hours at the temperature of 105 ℃. And finally, putting the obtained blocky solid into a muffle furnace, roasting for 3h at 350 ℃, naturally cooling to room temperature, and screening to 20-40 meshes for later use to obtain the No. 1 catalyst.
Example 2:
25L of RuCl with a concentration of 4g/L3·3H2O solution, 3.0064g Co (NO)3)2·6H2O，12.5508g Ce(NO3)2·6H2O and 8.6669g Zr (NO)3)2·5H2O is added to 100ml of deionized water and stirred in a water bath at 70 ℃ until completely dissolved. Adding 219ml of NaOH solution with the concentration of 1mol/L into the solution to adjust the pH value of the solution to 9-11, and stirring the solution under the condition of a water bath at 70 ℃ until the catalyst is sticky. The obtained sticky solid is centrifugally washed for 5 times at the rotating speed of 6000r/min and then is put into an oven to be dried for 12 hours at the temperature of 105 ℃. And finally, putting the obtained blocky solid into a muffle furnace, roasting for 3h at 350 ℃, naturally cooling to room temperature, and screening to 20-40 meshes for later use to obtain the 2# catalyst.
Test example 1:
the NO catalytic oxidation activity test was performed by taking the catalyst # 1 in example 1 and the catalyst # 2 in example 2 as examples. The raw material gas composition is as follows: 700ppm ofNO、5vol％O2The carrier gas is N2The space velocity is 30000h-1The catalytic oxidation efficiency of the catalyst at 160-340 ℃ is tested, and the test result is shown in figure 1. From the test results it can be seen that: the 2# catalyst shows good catalytic oxidation performance, and the NO conversion rate can reach more than 50% at 240 ℃, so that the reaction condition of rapid SCR is met.
Test example 2:
the NO catalytic oxidation water resistance test was performed by taking the catalyst # 1 in example 1 and the catalyst # 2 in example 2 as examples. The raw material gas composition is as follows: 700ppm NO, 5 vol% O2，5vol％H2O, carrier gas is N2The space velocity is 30000h-1The water resistance of the catalyst at 250 ℃ is tested, and the test result is shown in figure 2. From the test results it can be seen that: both the No. 1 and No. 2 catalysts showed good water resistance at 250 deg.C, 5 vol% H2After 8 hours of reaction in the presence of O, the performance of the catalyst is not affected basically.
Test example 3:
taking the catalyst # 1 in example 1 and the catalyst # 2 in example 2 as examples, the NO catalytic oxidation sulfur resistance test was performed. The raw material gas composition is as follows: 700ppm NO, 5 vol% O2，200ppm SO2The carrier gas is N2The space velocity is 30000h-1The sulfur resistance of the catalyst at 250 ℃ was tested, and the test results are shown in FIG. 3. From the test results it can be seen that: the sulfur resistance of the No. 2 catalyst is the best, and 200ppm SO is carried out at 250 DEG C2The activity of the catalyst can still be maintained at 30 percent after the reaction is carried out for 24 hours under the existing condition. And after the catalyst is heated and regenerated at 350 ℃, the activity of the catalyst can be recovered to 35 percent, and the Co-doped catalyst is proved to have better sulfur resistance.
Test example 4:
taking the catalyst # 1 in example 1 and the catalyst # 2 in example 2 as examples, the NO catalytic oxidation sulfur resistance water resistance test was performed. The raw material gas composition is as follows: 700ppm NO, 5 vol% O2，5vol％H2O，200ppm SO2The carrier gas is N2The space velocity is 30000h-1Testing the sulfur resistance and water resistance of the catalyst at 250 ℃, and testing results are shown asFig. 4. From the test results it can be seen that: the sulfur-resistant and water-resistant performance of the No. 1 catalyst is optimal, and 200ppm SO is applied at 250 DEG C2And 5 vol% H2After the reaction is carried out for 12 hours in the presence of O, the activity of the catalyst can still be maintained to be more than 35 percent. And after the catalyst is heated and regenerated at 350 ℃, the activity of the catalyst can be recovered to 40 percent, which proves that the catalyst has certain sulfur resistance and water resistance at medium and low temperature.
Test example 5:
the combined SCR catalyst experiment was performed with catalyst # 1 from example 1. The raw material gas composition is as follows: 700ppm NO, 5 vol% O2，700ppm NH3The carrier gas is N2The space velocity of the oxidation section is 150000h-1The space velocity of the SCR section is 250000h-1And testing the denitration efficiency at 160-340 ℃, wherein the test result is shown in figure 5. From the test results it can be seen that: after the denitration catalyst is combined with the No. 1 catalyst, the denitration efficiency of the SCR catalyst is obviously improved. When the temperature reaches 300 ℃, the denitration efficiency of the combined experiment can reach more than 90 percent and is far higher than the denitration efficiency of the single SCR.

Claims (5)

1. The cobalt-modified NO catalytic oxidant is characterized in that the mass fraction range of each component of the catalyst is as follows: active ingredient RuO2:0.5wt％、Co3O4:14-25wt％、CeO2:49-57wt％、ZrO2:24-29wt％。
2. The method of claim 1, comprising the steps of:
1) adding a ruthenium trichloride solution, cobalt nitrate hexahydrate, cerium nitrate hexahydrate and zirconium nitrate pentahydrate into deionized water, and stirring and dissolving at the temperature of 60-80 ℃;
2) adding NaOH solution into the solution generated in the step 1), adjusting the pH value to be 9-11, and stirring the solution at the temperature of 60-80 ℃ until the catalyst is viscous;
3) centrifugally washing the sticky solid obtained in the step 2) for 1-5 times at the rotating speed of 3000-8000 r/min;
4) putting the sticky solid obtained in the step 3) into an oven to be dried for 8-16h at 105 ℃;
5) and (3) putting the blocky solid obtained in the step 4) into a muffle furnace, roasting for 2-5h at 350-550 ℃, naturally cooling to room temperature, and screening to 20-40 meshes for later use.
3. A method according to claim 2, characterized in that: co in the final active component of the catalyst3O4：CeO2：ZrO2＝0.5：2:1-1:2:1。
4. A method according to claim 2, characterized in that: the roasting temperature of the muffle furnace in the step 5) is 350 ℃.
5. The method for realizing rapid SCR by using the cobalt-modified NO catalytic oxidizer of claim 1 in combination with an SCR catalyst, wherein the space velocity is set to 150000h before denitration reaction is carried out by using the SCR catalyst-1Oxidizing a part of NO in the flue gas into NO by using NO catalytic oxidant2NO and NO before the gas enters the SCR system2The volume ratio reaches 1:1, and then the space velocity of the denitration section is set to 250000h-1An SCR catalyst is used to facilitate the rapid SCR reaction.
CN202010154263.3A 2020-03-07 2020-03-07 Preparation method of cobalt-modified NO catalytic oxidant Pending CN111167477A (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1876331A2 (en) * 2006-07-08 2008-01-09 MAN Nutzfahrzeuge AG Assembly for reducing nitrogen oxides in exhaust gases
US20110258994A1 (en) * 2008-12-12 2011-10-27 Korea Institute Of Energy Research Bifunctional Catalyst for Decomposition and Oxidation of Nitrogen Monoxide, Composite Catalyst Including the Same for Apparatus to Decrease Exhaust Gas, and Method for Preparation Thereof
CN105688920A (en) * 2016-03-04 2016-06-22 北京工业大学 NO low-temperature catalytic oxidant and preparation method
CN108745364A (en) * 2018-05-15 2018-11-06 昆明理工大学 A kind of preparation method of perovskite catalyst for catalytic oxidation NO

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1876331A2 (en) * 2006-07-08 2008-01-09 MAN Nutzfahrzeuge AG Assembly for reducing nitrogen oxides in exhaust gases
US20110258994A1 (en) * 2008-12-12 2011-10-27 Korea Institute Of Energy Research Bifunctional Catalyst for Decomposition and Oxidation of Nitrogen Monoxide, Composite Catalyst Including the Same for Apparatus to Decrease Exhaust Gas, and Method for Preparation Thereof
CN105688920A (en) * 2016-03-04 2016-06-22 北京工业大学 NO low-temperature catalytic oxidant and preparation method
CN108745364A (en) * 2018-05-15 2018-11-06 昆明理工大学 A kind of preparation method of perovskite catalyst for catalytic oxidation NO

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
YIWEN DONG等: ""Sulfur and Water Resistance and Activity of Ru-Ce-Zr-Ox Catalysts for Nitric Oxide Catalytic Oxidation", 《EARTH AND ENVIRONMENTAL SCIENCE》 *
商丹红: "Co基催化剂的制备及其催化氧化NO的性能研究", 《万方学位论文》 *
翟步英等: "柴油车尾气净化催化剂发展趋势", 《材料导报》 *

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