Regeneration method of marine vanadium-titanium denitration catalyst

Abstract

The invention discloses a regeneration method of a marine vanadium-titanium denitration catalyst. The regeneration method comprises the following steps: (1) immersing a deactivated catalyst into a diluent of a special cleaning agent for grease for cleaning; (2) carrying out spray cleaning on the catalyst cleaned in the step (1), wherein a spray cleaning solution is water; (3) carrying out acid chemical cleaning on the catalyst cleaned in the step (2) to remove alkali metal harmful substances such as sodium, potassium and the like attached to the catalyst; (4) washing the catalyst cleaned in the step (3) with water; (5) drying the catalyst cleaned in the step (4); (6) the catalyst dried in the step (5) is soaked in an active solution for active reimplantation, and the active solution mainly comprises ammonium paratungstate and ammonium molybdate and further comprises one of ammonium metavanadate and vanadyl oxalate; and (7) draining the catalyst subjected to activity reimplantation in the step (6), and putting the catalyst into a calcining furnace for activity activation. According to the method disclosed by the invention, more than 98% of pollutants such as grease, ash, alkali metal and sulfate can be removed, and the use temperature after regeneration is reduced by 20-60 DEG C compared with the original use temperature.

Description

Technical Field

[0001] The invention relates to the technical field of resource recycling, and in particular to a method for regenerating a marine vanadium-titanium denitration catalyst. Background Art

[0002] In October 2008, the International Maritime Organization adopted amendments to Annex VI "Regulations for the Prevention of Air Pollution from Ships", which set stricter standards for SO2, SO3, and NO X Emission regulations. According to the amendment to Annex VI, by 2016, low-speed diesel engines NO x The emission limit of high-speed diesel engines should be reduced from 17.0g / (kW·h) to 3.4g / (kW·h). x The emission limit should be reduced from 9.8g / (kW·h) to 1.96g / (kW·h). Faced with such strict international emission regulations, marine SCR (selective catalytic reduction) denitrification has been widely used. However, it is worth noting that the vanadium-titanium catalyst in the marine SCR denitrification system is very easy to lose its activity during use, which increases the cost of denitrification and generates a large amount of secondary hazardous waste.

[0003] The combustion of heavy oil fuel used in ship diesel engines will produce pollutants such as alkali metals, SO2, and SO3, causing the vanadium-titanium denitrification catalyst used to gradually deactivate due to alkali metal poisoning, sulfate clogging and other problems. Incompletely burned grease substances will also cover the catalyst, causing the catalyst to deactivate. Invention patent CN201510941940 "A vanadium-titanium catalyst regeneration process for marine SCR denitrification" proposes a method of first carbonization and then oxidation to remove grease pollutants on the catalyst, and after further chemical cleaning, drying, and regeneration liquid impregnation process, the catalyst is restored to activity. However, the "first carbonization and then oxidation" process used in this method consumes a lot of heat, which is inconsistent with the requirements of energy conservation and environmental protection, and high-temperature calcination easily causes thermal sintering of the active substances on the catalyst, and the original active substances on the deactivated catalyst cannot be used, and may even cause the catalyst to internally burn, destroying the catalyst. This method can only restore the activity of the catalyst, but cannot improve the low-temperature activity of the catalyst and broaden the conditions of use. The existing technology is difficult to meet the needs of energy conservation, environmental protection and improved catalytic performance. Therefore, it is very necessary to seek a more energy-saving and environmentally friendly, process-reliable and catalytic performance-enhanced marine vanadium-titanium denitrification catalyst regeneration process. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention aims to restore the activity of the catalyst through a method that is more energy-saving and environmentally friendly and can improve catalytic performance, thereby reducing the cost of denitrification and reducing secondary hazardous waste.

[0005] The present invention provides a method for regenerating a marine vanadium-titanium denitration catalyst, comprising the following steps:

[0006] (1) Immersing the deactivated catalyst in a diluent of a special cleaning agent for grease for cleaning; wherein the mass percentage of each component in the diluent of the special cleaning agent for grease is: 3% to 7% of fatty alcohol polyoxyethylene ether, 1% to 7% of sodium secondary alkyl sulfonate, 2% to 13% of ethanol, 1% to 3% of sodium hydroxide, 1% to 5% of triethanolamine, 0.1% to 0.7% of sodium tripolyphosphate, 0.1% to 0.5% of kason, and the rest is water; the mass / volume ratio of the deactivated catalyst to the diluent of the special cleaning agent for grease is 1g: (40 to 60) mL; the deactivated catalyst is a deactivated marine vanadium-titanium denitration catalyst;

[0007] (2) spray cleaning the catalyst cleaned in step (1), wherein the spray cleaning liquid is water;

[0008] (3) subjecting the catalyst cleaned in step (2) to acid chemical cleaning to remove harmful alkali metal substances such as sodium and potassium attached to the catalyst;

[0009] (4) washing the catalyst cleaned in step (3) with water;

[0010] (5) drying the catalyst cleaned in step (4);

[0011] (6) immersing the catalyst dried in step (5) in an active solution for active re-implantation, wherein the active solution mainly comprises ammonium paratungstate and ammonium molybdate, and also comprises one of ammonium metavanadate and vanadyl oxalate;

[0012] (7) After the active re-implantation in step (6), the catalyst is drained and placed in a calcining furnace for activation. The calcination temperature is 200 to 450° C. and the calcination time is 60 to 90 minutes.

[0013] As an example, in step (6), the mass proportions of the components in the active solution are: ammonium paratungstate 20.27-47.29% (corresponding to 1.5-3.5% tungsten trioxide), ammonium molybdate 1.36-4.08% (corresponding to 1-3% molybdenum trioxide), ammonium metavanadate 0.96-2.25% (corresponding to 1.5-3.5% vanadium pentoxide) or vanadyl oxalate 2.02-4.72% (corresponding to 1.5-3.5% vanadium pentoxide).

[0014] In step (7), the ammonium metavanadate or vanadyl oxalate, ammonium paratungstate, and ammonium molybdate in the catalyst are calcined and decomposed to form active substances such as vanadium pentoxide, tungsten trioxide, and molybdenum trioxide. The calcined catalyst is packaged to form a product.

[0015] Furthermore, during the cleaning process of step (1), bubbles are blown upward from the bottom of the cleaning container to keep the liquid in the container flowing. The preferred cleaning temperature of step (1) is 60°C to 80°C, the time is 60 to 120 minutes, and the mass / volume ratio of the deactivated catalyst to the grease-specific cleaning agent diluent is 1g: (40 to 60) mL.

[0016] Furthermore, in step (2), the spray cleaning time is 60 to 90 minutes, and the mass / volume ratio of the catalyst to the cleaning water is 1 g: (40 to 60) mL.

[0017] Furthermore, during the acid chemical cleaning process in step (3), the cleaning temperature is 25 to 80° C. The preferred cleaning time in step (3) is 60 to 120 min.

[0018] Furthermore, the acid chemical cleaning solution used in step (3) is a mixture of one or more acids selected from sulfuric acid, hydrochloric acid, phosphoric acid and nitric acid, and the mass concentration of the acid in the cleaning solution is 0.5% to 2%, and the rest is water.

[0019] Furthermore, during the acid chemical cleaning process in step (3), the mass / volume ratio of the catalyst to the acid chemical cleaning solution is 1 g: (40-60) mL.

[0020] Furthermore, during the water washing process in step (4), the washing temperature is 25 to 50° C. The preferred washing time in step (4) is 60 to 120 min.

[0021] Furthermore, during the water washing process in step (4), the ratio of catalyst to washing water is 1 g: (40-60) mL.

[0022] Furthermore, in step (5), the drying temperature is 80-100° C., and the drying time is 90-150 min.

[0023] Furthermore, the immersion time in step (6) is 10 to 30 minutes and the temperature is 25 to 35°C.

[0024] Furthermore, the weight of the regenerated catalyst after calcination in step (7) is increased by 4 to 8% compared to the catalyst after drying in step (5).

[0025] The water mentioned in each step of the present invention can be tap water or pure water, preferably tap water, which has a greater cost advantage. Compared with the prior art, the technical effects of the present invention are:

[0026] (1) Through the regeneration process of the present invention, more than 98% of pollutants such as grease, ash, alkali metals, and sulfates on the catalyst can be removed, effectively restoring the cleanliness of the catalyst;

[0027] (2) The active substances added during the regeneration process not only restore the catalytic performance of the catalyst, but also improve the low-temperature catalytic activity of the catalyst. The minimum operating temperature of the catalyst after regeneration can be reduced by 20 to 60°C compared with the original temperature. The minimum operating temperature of the original fresh catalyst is 290°C, and the catalyst dosage is 3.6m 3 , denitrification efficiency ≥ 80%; under the same catalyst dosage, the minimum operating temperature of the regenerated catalyst is 230-270°C, and the denitrification efficiency can still reach 80% and above.

[0028] (3) The regenerated catalyst substrate is not damaged and can be directly returned to the SCR reactor for use, reducing the cost of replacing new catalysts and environmental pressure.

[0029] (4) Compared with the invention patent CN201510941940, the present invention can more effectively utilize the original active substances such as vanadium and tungsten on the deactivated catalyst, and the supplementary amount of vanadium pentoxide and tungsten trioxide can be reduced by 20-50%, further improving resource utilization and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The present invention is a process flow chart of a method for regenerating a marine vanadium-titanium denitration catalyst. DETAILED DESCRIPTION

[0031] The present invention is further described below in conjunction with the embodiments and drawings, but the contents of the present invention are not limited thereto.

[0032] The "deactivated catalyst" used in the following examples is a vanadium-titanium catalyst TEX2722-46 cpsi for SCR denitrification in exhaust gas from a marine engine that has been deactivated after running for 20,000 hours.

[0033] Example 1

[0034] Prepare a special grease cleaning agent diluent: 5% fatty alcohol polyoxyethylene ether (AEO-20), 7% sodium secondary alkyl sulfonate (SAS-60), 10% ethanol, 2% sodium hydroxide, 1% triethanolamine, 0.7% sodium tripolyphosphate, 0.3% kason, and the rest is water.

[0035] Immerse the deactivated catalyst in a special cleaning agent diluent for grease for cleaning; the cleaning temperature is 80℃ and the time is 90min. The mass / volume ratio of the catalyst to the cleaning agent diluent is 1g:60mL. During the cleaning process, bubble upward from the bottom of the cleaning container to keep the liquid in the container flowing.

[0036] The cleaned catalyst was spray-cleaned for 90 minutes, and the spray-cleaning liquid was tap water. The ratio of catalyst to tap water was 1 g: 60 mL.

[0037] The above-mentioned spray-cleaned catalyst is subjected to acid chemical cleaning to remove harmful alkali metal substances such as sodium and potassium attached to the catalyst. The cleaning temperature is 50°C and the cleaning time is 90 minutes. The component of the acid chemical cleaning liquid is sulfuric acid. The mass content of sulfuric acid in the cleaning liquid is 1%, and the rest is water. The ratio of catalyst to cleaning liquid is 1g:60mL.

[0038] The catalyst that has been chemically cleaned with acid is washed with water. The washing temperature is 50°C and the washing time is 90 minutes. The water is tap water. The ratio of catalyst to washing water is 1g:60mL.

[0039] The washed catalyst was dried at 80°C for 150 minutes.

[0040] The dried samples were sampled for composition and crystal form inspection, and compared with the data of the deactivated catalyst, the analysis showed that the removal rate of oil, ash, alkali metal and sulfate pollutants on the catalyst was 99%, the remaining vanadium pentoxide was 70% recyclable, and the remaining tungsten trioxide was 90% recyclable.

[0041] The dried catalyst is placed in an active solution impregnation tank for active re-implantation. The impregnation time is 10 minutes and the temperature is 35°C. The main components of the active solution are 3.5% vanadyl oxalate (calculated as vanadium pentoxide), 3.5% ammonium paratungstate (calculated as tungsten trioxide) and 3% ammonium molybdate (calculated as molybdenum trioxide).

[0042] After the active re-implantation, the catalyst is drained and placed in a calcination furnace for activation. The calcination temperature is 300°C and the calcination time is 90 minutes. After calcination, the vanadium oxalate, ammonium paratungstate, and ammonium molybdate in the catalyst decompose to form active substances such as vanadium pentoxide, tungsten trioxide, and molybdenum trioxide. The calcined regenerated catalyst is packaged to form a product. The weight of the calcined regenerated catalyst is increased by 8% compared to the previously washed and dried catalyst.

[0043] The minimum operating temperature for the denitration efficiency of the deactivated catalyst to reach 80% or above before deactivation is 290℃. Under the original working conditions of the deactivated catalyst, the catalytic performance of the regenerated catalyst was tested. The evaluation of the regenerated catalyst was carried out in a stainless steel hollow tube denitration reactor with a diameter of 5cm and a height of 100cm. The reaction temperature was 290℃, the gas flow rate was 4500L / h, the gas inlet composition was NO: 550ppm, SO2: 1500ppm, O2: 8.5%, and the rest was nitrogen. The regenerated catalyst particles were sprayed at a rate of 92g / h by pneumatic injection. The gas outlet concentration was analyzed online by the Testo340 flue gas analyzer, and the sample was automatically taken every two minutes. When the operation reached stability, the gas outlet concentration was NO: 28~32ppm, and the denitration efficiency was 94~95%. The test showed that the catalyst could fully meet the use requirements. On this basis, the use temperature was gradually reduced until it was reduced by 60℃, and the denitration efficiency could still reach 82~83%. The test showed that the catalyst could still meet the use requirements.

[0044] Example 2

[0045] Prepare a special grease cleaning agent diluent: 3% fatty alcohol polyoxyethylene ether (AEO-20), 1% sodium secondary alkyl sulfonate (SAS-60), 13% ethanol, 1% sodium hydroxide, 5% triethanolamine, 0.1% sodium tripolyphosphate, 0.5% kason, and the rest is water.

[0046] Immerse the deactivated catalyst in a special cleaning agent diluent for grease for cleaning; the cleaning temperature is 60°C and the time is 120 minutes. The mass / volume ratio of the catalyst to the cleaning agent diluent is 1g:40mL. During the cleaning process, bubble upward from the bottom of the cleaning container to keep the liquid in the container flowing.

[0047] The cleaned catalyst was spray-cleaned for 60 minutes, and the spray-cleaning liquid was tap water. The ratio of catalyst to tap water was 1 g:40 mL.

[0048] The above-mentioned spray-cleaned catalyst is subjected to acid chemical cleaning to remove harmful alkali metal substances such as sodium and potassium attached to the catalyst. The cleaning temperature is 25°C and the cleaning time is 120 minutes. The component of the acid chemical cleaning liquid is nitric acid. The mass content of nitric acid in the cleaning liquid is 0.5%, and the rest is water. The ratio of catalyst to cleaning liquid is 1g:40mL.

[0049] The catalyst that has been chemically cleaned with acid is washed with water. The washing temperature is 25°C and the washing time is 60 minutes. The water is tap water. The ratio of catalyst to washing water is 1g:40mL.

[0050] The washed catalyst was dried at a temperature of 100° C. and a drying time of 90 min.

[0051] The dried samples were sampled for composition and crystal form inspection, and compared with the data of the deactivated catalyst, the analysis showed that the removal rate of oil, ash, alkali metal and sulfate pollutants on the catalyst was 99%, the remaining vanadium pentoxide was 70% recyclable, and the remaining tungsten trioxide was 90% recyclable.

[0052] The dried catalyst is placed in an active solution impregnation tank for active re-implantation. The impregnation time is 30 minutes and the temperature is 25°C. The main components of the active solution are 2.5% vanadyl oxalate (calculated as vanadium pentoxide), 2.5% ammonium paratungstate (calculated as tungsten trioxide) and 2% ammonium molybdate (calculated as molybdenum trioxide).

[0053] After the active re-implantation, the catalyst is drained and placed in a calcination furnace for activation. The calcination temperature is 300°C and the calcination time is 90 minutes. After calcination, the vanadium oxalate, ammonium paratungstate and ammonium molybdate in the catalyst decompose to form active substances such as vanadium pentoxide, tungsten trioxide and molybdenum trioxide. The regenerated catalyst after calcination is packaged to form a product. The weight of the regenerated catalyst after calcination is increased by 5% compared to the catalyst after washing and drying.

[0054] The minimum operating temperature for the denitration efficiency of the deactivated catalyst to reach 80% or above before deactivation is 290℃. Under the original working conditions of the deactivated catalyst, the catalytic performance of the regenerated catalyst was tested. The evaluation of the regenerated catalyst was carried out in a stainless steel hollow tube denitration reactor with a diameter of 5cm and a height of 100cm. The reaction temperature was 290℃, the gas flow rate was 4500L / h, the gas inlet composition was NO: 550ppm, SO2: 1500ppm, O2: 8.5%, and the rest was nitrogen. The regenerated catalyst particles were sprayed at a rate of 92g / h by pneumatic injection. The gas outlet concentration was analyzed online by the Testo340 flue gas analyzer, and the sample was automatically taken every two minutes. When the operation reached stability, the gas outlet concentration was NO: 30~34ppm, and the denitration efficiency was 93.8~94.5%. The test showed that the catalyst could fully meet the use requirements. On this basis, the use temperature was gradually reduced until it was reduced by 40℃, and the denitration efficiency could still reach 81~82%. The test showed that the catalyst could still meet the use requirements.

[0055] Example 3

[0056] Prepare a special grease cleaning agent diluent: fatty alcohol polyoxyethylene ether (AEO-20) 7%, sodium secondary alkyl sulfonate (SAS-60) 7%, ethanol 2%, sodium hydroxide 3%, triethanolamine 1%, sodium tripolyphosphate 0.7%, kason 0.1%, and the rest is water.

[0057] Immerse the deactivated catalyst in a special cleaning agent diluent for grease for cleaning; the cleaning temperature is 80℃ and the time is 90min. The mass / volume ratio of the catalyst to the cleaning agent diluent is 1g:60mL. During the cleaning process, bubble upward from the bottom of the cleaning container to keep the liquid in the container flowing.

[0058] The cleaned catalyst was spray-cleaned for 90 minutes, and the spray-cleaning liquid was tap water. The ratio of catalyst to tap water was 1 g: 60 mL.

[0059] The above-mentioned spray-cleaned catalyst is subjected to acid chemical cleaning to remove harmful alkali metal substances such as sodium and potassium attached to the catalyst. The cleaning temperature is 80°C and the cleaning time is 60 minutes. The composition of the acid chemical cleaning liquid is hydrochloric acid. The mass content of hydrochloric acid in the cleaning liquid is 2%, and the rest is water. The ratio of catalyst to cleaning liquid is 1g:60mL.

[0060] The catalyst that has been chemically cleaned with acid is washed with water. The washing temperature is 50°C and the washing time is 120 minutes. The water is tap water. The ratio of catalyst to washing water is 1g:60mL.

[0061] The washed catalyst was dried at 80°C for 150 minutes.

[0062] The dried samples were sampled for composition and crystal form inspection, and compared with the data of the deactivated catalyst, the analysis showed that the removal rate of oil, ash, alkali metal and sulfate pollutants on the catalyst was 99%, the remaining vanadium pentoxide was 70% recyclable, and the remaining tungsten trioxide was 90% recyclable.

[0063] The dried catalyst is placed in an active solution impregnation tank for active re-implantation. The impregnation time is 10 minutes and the temperature is 35°C. The main components of the active solution are 2.0% vanadyl oxalate (calculated as vanadium pentoxide), 2.0% ammonium paratungstate (calculated as tungsten trioxide) and 1% ammonium molybdate (calculated as molybdenum trioxide).

[0064] After the active re-implantation, the catalyst is drained and placed in a calcination furnace for activation. The calcination temperature is 450°C and the calcination time is 60 minutes. After calcination, the vanadium oxalate, ammonium paratungstate, and ammonium molybdate in the catalyst decompose to form active substances such as vanadium pentoxide, tungsten trioxide, and molybdenum trioxide. The calcined regenerated catalyst is packaged to form a product. The weight of the calcined regenerated catalyst is increased by 4% compared to the previously washed and dried catalyst.

[0065] The minimum operating temperature for the denitration efficiency of the deactivated catalyst to reach 80% or above before deactivation is 290℃. Under the original working conditions of the deactivated catalyst, the catalytic performance of the regenerated catalyst was tested. The evaluation of the regenerated catalyst was carried out in a stainless steel hollow tube denitration reactor with a diameter of 5cm and a height of 100cm. The reaction temperature was 290℃, the gas flow rate was 4500L / h, the gas inlet composition was NO: 550ppm, SO2: 1500ppm, O2: 8.5%, and the rest was nitrogen. The regenerated catalyst particles were sprayed at a rate of 92g / h by pneumatic injection. The gas outlet concentration was analyzed online by the Testo340 flue gas analyzer, and the sample was automatically taken every two minutes. When the operation reached stability, the gas outlet concentration was NO: 38~42ppm, and the denitration efficiency was 92~93%. The test showed that the catalyst could fully meet the use requirements. On this basis, the use temperature was gradually reduced until it was reduced by 30℃, and the denitration efficiency could still reach 80~81%. The test showed that the catalyst could still meet the use requirements.

Claims

1. A method for regenerating a marine vanadium-titanium denitration catalyst, characterized in that: The following steps are involved: (1) Immersing the deactivated catalyst in a diluent of a special cleaning agent for grease for cleaning; wherein the mass percentage of each component in the diluent of the special cleaning agent for grease is: 3% to 7% of fatty alcohol polyoxyethylene ether, 1% to 7% of sodium secondary alkyl sulfonate, 2% to 13% of ethanol, 1% to 3% of sodium hydroxide, 1% to 5% of triethanolamine, 0.1% to 0.7% of sodium tripolyphosphate, 0.1% to 0.5% of kason, and the rest is water; the deactivated catalyst is a deactivated marine vanadium-titanium denitrification catalyst; (2) spray cleaning the catalyst cleaned in step (1), wherein the spray cleaning liquid is water; (3) subjecting the catalyst cleaned in step (2) to acid chemical cleaning to remove harmful alkali metal substances such as sodium and potassium attached to the catalyst; (4) washing the catalyst cleaned in step (3) with water; (5) drying the catalyst cleaned in step (4); (6) immersing the catalyst dried in step (5) in an active solution for active re-implantation, wherein the active solution mainly comprises ammonium paratungstate and ammonium molybdate, and also comprises one of ammonium metavanadate and vanadyl oxalate; (7) After the active re-implantation in step (6), the catalyst is drained and placed in a calcining furnace for activation. The calcination temperature is 200 to 450° C. and the calcination time is 60 to 90 minutes.

2. The regeneration method according to claim 1, characterized in that: During the cleaning process of step (1), bubbles are blown upward from the bottom of the cleaning container to keep the liquid in the container flowing.

3. The regeneration method according to claim 1, characterized in that: In step (2), the spray cleaning time is 60 to 90 minutes, and the mass / volume ratio of the catalyst to the cleaning water is 1 g: (40 to 60) mL.

4. The regeneration method according to claim 1, characterized in that: During the acid chemical cleaning process in step (3), the cleaning temperature is 25 to 80° C. and the cleaning time is 60 to 120 minutes.

5. The regeneration method according to claim 1, characterized in that: The acid chemical cleaning solution used in step (3) is a mixture of one or more acids selected from the group consisting of sulfuric acid, hydrochloric acid, phosphoric acid, and nitric acid. The mass concentration of the acid in the cleaning solution is 0.5% to 2%, and the remainder is water.

6. The regeneration method according to claim 1, characterized in that: During the water washing process in step (4), the washing temperature is 25 to 50°C.

7. The regeneration method according to claim 1, characterized in that: The drying temperature in step (5) is 80-100° C. and the drying time is 90-150 min.

8. The regeneration method according to claim 1, characterized in that: The immersion time in step (6) is 10 to 30 minutes, and the temperature is 25 to 35°C.

9. The regeneration method according to claim 1, characterized in that: The weight of the regenerated catalyst after calcination in step (7) is increased by 4 to 8% compared to the catalyst after drying in step (5).

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