CN107497299B

CN107497299B - MnO (MnO)xRegeneration method for failure of PG denitration catalyst

Info

Publication number: CN107497299B
Application number: CN201710953984.9A
Authority: CN
Inventors: 张先龙; 蔡程; 吴雪平
Original assignee: Hefei University of Technology
Current assignee: Hefei University of Technology
Priority date: 2017-10-13
Filing date: 2017-10-13
Publication date: 2020-10-16
Anticipated expiration: 2037-10-13
Also published as: CN107497299A

Abstract

The invention relates to the field of catalyst regeneration, and particularly provides MnO_xA method for regenerating a PG denitration catalyst, comprising the steps of: 1. MnO poisoned with sulfur_xSoaking the PG denitration catalyst in deionized water, and placing the catalyst in a water bath constant temperature oscillator; 2. adjusting the temperature of the water bath constant temperature oscillator to 30 ℃, setting the oscillation frequency to be 120Hz, changing the solid-liquid ratio of the deactivated catalyst and the regenerant, and keeping the deactivated catalyst soaked in the deionized water to oscillate in the water bath constant temperature oscillator for 10 min. 3. MnO treated by the step (2)_xThe PG denitration catalyst is filtered and then is dried by microwave, the temperature is raised to 110 ℃ at the speed of not more than 5 ℃/min, and the temperature is kept for 3 hours to obtain regenerated MnO_xA PG denitration catalyst. By the catalyst regeneration method, the activity of the obtained regenerated catalyst can be recovered to the activity of a fresh catalyst, the service life of the catalyst is prolonged, and the method is simple in process, low in regeneration cost, environment-friendly and suitable for industrial production and application.

Description

MnO (MnO)xRegeneration method for failure of PG denitration catalyst

Technical Field

The invention relates to the field of catalyst regeneration, in particular to a regeneration method of a MnOx/PG denitration catalyst after sulfur poisoning.

Background

Nitrogen oxides are one of the main air pollutants causing environmental problems such as acid rain, photochemical smog and the like, and are also the key points and difficulties in the protection of the atmospheric environment at present. Each country to NO_xAre subject to strict restrictions and are targeted more and more. China started to process NO from 2004_xAnd collecting pollution discharge fee, and carrying out flue gas denitration in China on a large scale.

Selective Catalytic Reduction (SCR) denitration is currently the most mainstream flue gas denitration technology in the world, wherein a catalyst is the core of the technology. At present, research and development of low-temperature SCR catalysts at home and abroad are mainly focused on transition metal oxides, and Mn, Co and Cu are more active components. Research shows that the metal with the best low-temperature denitration activity is Mn, and the carrier mainly comprises TiO₂Molecular sieve, active carbon, attapulgite and the like, and the result shows that the denitration catalyst taking the attapulgite as a carrier has good medium-low temperature catalytic performance. The attapulgite has the advantages of easy molding, high temperature resistance, high mechanical strength, large specific surface area and the like, greatly reduces the process cost of the catalyst, and provides industrial extraction for the catalystProviding a theoretical basis.

MnO in low-temperature denitration of flue gas in non-electric industry_xthe/PG low-temperature SCR catalyst is widely applied to low-temperature SCR denitration of coke oven flue gas. However MnO_xthe/PG denitration catalyst is easy to be poisoned by sulfur in a medium-low temperature environment and gradually deactivated. The poisoning and deactivation of the catalyst reduces the service life of the catalyst and increases the cost of denitration. Therefore, in order to improve the secondary recovery utilization rate of the catalyst resources and save the denitration cost, the regeneration of the deactivated catalyst is especially necessary and important.

The following regeneration methods are commonly used, as found in the relevant literature: water washing regeneration, gas thermal regeneration and reduction regeneration, and in general, the water washing regeneration can wash out substances deposited on the surface of the catalyst. The thermal regeneration can convert the sulfur adsorbed on the surface of the catalyst into SO₂. The reduction regeneration can reduce the formed sulfate into SO₂At the same time SO₂Can be converted into H by further treatment₂SO₄Or elemental sulfur. For example, herba cistanches, etc. in the regeneration method pair V₂O₅Effect of the simultaneous desulfurization and denitration Activity of the/AC catalyst Water Wash regeneration, Ar thermal regeneration and 5% NH₃Three regeneration method pairs V of-95% Ar reduction regeneration₂O₅The result shows that although the water washing can wash off the sulfur-containing substances on the surface of the catalyst, part of active components can be washed off, and the denitration activity of the catalyst can be recovered to a certain extent by both the thermal regeneration and the reduction regeneration. Huyufeng et al in Mn-Ce/TiO₂In the low-temperature selective catalytic reduction catalyst sulfur dioxide poisoning and regeneration characteristics, three methods of water washing, thermal regeneration and reduction gas reduction regeneration are adopted to carry out the reaction on Mn-Ce/TiO₂The catalyst is regenerated, and the result shows that the regeneration effect of the three methods is the best in water washing.

Disclosure of Invention

The invention aims to provide MnO_xThe regeneration method of the PG denitration catalyst after sulfur poisoning is used for improving the utilization rate of the deactivated catalyst.

The purpose of the invention can be realized by the following technical scheme:

MnO (MnO)_xThe regeneration method for the PG denitration catalyst failure comprises the following steps:

1) poisoning sulfur by MnO_xSoaking the PG denitration catalyst in deionized water, and placing the catalyst in a water bath constant temperature oscillator;

2) adjusting the temperature of a water bath constant temperature oscillator to 30 ℃, setting the oscillation frequency to be 120Hz, changing the solid-liquid ratio of the deactivated catalyst and the regenerant, and keeping the deactivated catalyst soaked in the deionized water to oscillate in the water bath constant temperature oscillator for 10 min;

3) MnO is obtained after the treatment of the step (2)_xThe PG catalyst is filtered and then dried by microwave, the temperature is raised to 110 ℃ at the temperature rise rate of not more than 5 ℃/min, and the temperature is preserved for 3 hours to obtain regenerated MnO_xA PG denitration catalyst.

Further, in step 2) of the technical scheme of the invention, the solid-to-liquid ratio is set to be 2:1, 1:2, 1:4 and 1: 6.

Further, in step 3) of the technical scheme of the invention, the microwave drying is performed for 3 hours at 110 ℃.

The invention has the beneficial effects that: the invention adopts attapulgite which is easy to form, high temperature resistant and high in mechanical strength as a carrier of the manganese-based denitration catalyst to prepare MnO_xThe structure of the PG catalyst cannot be damaged in the regeneration process after sulfur poisoning, the original physical structure is preserved, and the regeneration effect can be optimized by adjusting the solid-liquid ratio of the ineffective catalyst and the regenerant. MnO regenerated by the method of the invention is subjected to denitration activity evaluation test, ion titration analysis of regenerated liquid and XRF analysis of Mn element_xA/PG denitration catalyst, in which ammonium sulfate deposited on the surface thereof is washed off completely and Mn as an active component is not lost, so that the denitration activity thereof can be restored to fresh MnO_xthe/PG denitration catalyst level.

The method is simple and convenient to operate, environment-friendly and suitable for industrial production and application.

Drawings

FIG. 1 is a graph showing the evaluation of the activity of fresh, sulfur-poisoned, regenerated catalysts in examples 1 to 5 and regenerated catalysts in comparative examples.

FIG. 2 is an SEM image of a fresh MnOx/PG catalyst.

FIG. 3 is an SEM image of a sulfur-poisoned MnOx/PG catalyst.

FIG. 4 is an SEM image of a MnOx/PG catalyst after water-washing regeneration.

FIG. 5 is a graph of an ion titration analysis of the liquid after regeneration by water washing.

Detailed Description

The invention is described in further detail below with reference to the figures and specific examples.

Example 1

1. MnO poisoned with 2g of sulfur_xthe/PG denitration catalyst was immersed in 1ml of deionized water and placed in a water bath constant temperature oscillator.

2. Adjusting the temperature of the water bath constant temperature oscillator to 30 ℃, setting the oscillation frequency to be 120Hz, and oscillating the deactivated catalyst soaked in the deionized water in the water bath constant temperature oscillator for 10 min.

3. MnO is obtained after the treatment of the step (2)_xThe PG catalyst is filtered and then dried by microwave, the temperature is raised to 110 ℃ at the temperature rise rate of not more than 5 ℃/min, and the temperature is preserved for 3 hours to obtain regenerated MnO_xA PG denitration catalyst.

Example 2

1. MnO poisoned with 2g of sulfur_xthe/PG denitration catalyst was immersed in 2ml of deionized water and placed in a water bath constant temperature oscillator.

Example 3

1. MnO poisoned with 2g of sulfur_xthe/PG denitration catalyst was immersed in 4ml of deionized water and placed in a water bath constant temperature oscillator.

Example 4

1. MnO poisoned with 2g of sulfur_xthe/PG denitration catalyst was immersed in 8ml of deionized water and placed in a water bath constant temperature oscillator.

Example 5

1. MnO poisoned with 2g of sulfur_xthe/PG denitration catalyst was immersed in 12ml of deionized water and placed in a water bath constant temperature oscillator.

3. Will pass through step (2)) Treated to obtain MnO_xThe PG catalyst is filtered and then dried by microwave, the temperature is raised to 110 ℃ at the temperature rise rate of not more than 5 ℃/min, and the temperature is preserved for 3 hours to obtain regenerated MnO_xA PG denitration catalyst.

Comparative example

MnO (MnO)_xThe PG denitration catalyst failure regeneration method comprises the following steps: 2g of the deactivated catalyst is put into a tubular furnace, the temperature is raised to 450 ℃ at the heating rate of 5 ℃/min for 3 hours, and air is used as protective gas in the heating process.

Adding fresh MnO_xMnO containing/PG catalyst and sulfur poisoning_x[ PG catalyst, regenerated MnO obtained in examples 1 to 5_xCatalyst for PG and regenerated MnO prepared in comparative example_xThe PG catalyst is subjected to a denitration activity test, and the test method comprises the following steps: the catalyst denitration activity evaluation is carried out in a normal pressure fixed bed reactor and is heated by a tubular electric furnace. The simulated smoke composition is 600ppmNH₃、600ppmNO、 3％O₂Ar is equilibrium gas and 400ppm SO₂The total flow rate is 350mL/min, and the space velocity is 6500h^-1. The reaction temperature range is 100-300 ℃. The inlet and outlet NO concentrations were measured by a Testo350 model flue gas analyzer. The denitration activity of the catalyst is expressed by the conversion rate of NO:

in the formula (I), the compound is shown in the specification,

representing the concentration of NO at the inlet and outlet, respectively

As can be seen from FIG. 1, fresh regenerated MnO_xCatalyst for PG catalysis in the presence of SO₂After poisoning, the denitration activity of the catalyst is obviously reduced, namely the denitration activity is reduced from 42% to 11% at the temperature of 150 ℃ and is reduced from 86% to 24% at the temperature of 200 ℃; after the sulfur poisoning catalyst is thermally regenerated, denitration can be only partially recovered, after the sulfur poisoning catalyst is regenerated by water washing, denitration activity can be recovered to a fresh level, and the solid-to-liquid ratio of the deactivated catalyst to the regenerant cannot be higher than 1: 4. FIGS. 2, 3 and 4 are SEM images of fresh catalyst, sulfur-poisoned catalyst and regenerated catalyst, respectively, and it can be seen that freshMnO_xThe surface of the PG catalyst is smooth, and the dispersion is uniform; after poisoning in sulfur-containing atmosphere, a layer of white substance is obviously coated on the surface of the catalyst, and the catalyst is obviously inferior to a fresh catalyst in aggregation and dispersion; the poisoned catalyst can effectively remove the white substance on the surface of the catalyst through water washing, and recovers the rod-shaped structure of the catalyst, and the surface is relatively smooth. FIG. 5 is an ion titration analysis chart of a liquid after water washing regeneration, in which a solid-to-liquid ratio is 1:6, and 1-6 indicate temperatures of 20 ℃ to 70 ℃ respectively (temperature interval is 10 ℃), and it can be seen that the cause of sulfur poisoning of the catalyst is deposition of ammonium sulfate salt formed on the surface of the catalyst, and the ammonium sulfate salt can be completely washed away by water washing regeneration. Table 1 shows the XRF of the catalyst before and after sulfur poisoning and water washing regeneration, and it can be seen that the active components of the catalyst are not washed away after water washing regeneration, so the activity can be restored to a fresh state.

TABLE 1

While the foregoing is directed to 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.

Claims

1. A MnOx/PG denitration catalyst failure regeneration method is characterized by comprising the following steps:

(1) dipping a sulfur poisoned MnOx/PG denitration catalyst in deionized water, and placing the dipped sulfur poisoned MnOx/PG denitration catalyst in a water bath constant temperature oscillator;

(2) adjusting the temperature of the water bath constant temperature oscillator to 30 ℃, setting the oscillation frequency to be 120Hz, changing the solid-to-liquid ratio of the deactivated catalyst and the deionized water, and keeping the deactivated catalyst soaked in the deionized water to oscillate in the water bath constant temperature oscillator for 10 min; the solid-to-liquid ratio of the sulfur poisoned MnOx/PG denitration catalyst to the deionized water is selected from 2 g: 1ml, 1 g: 2ml, 1 g: 4ml and 1 g: 6 ml;

(3) and (3) filtering the MnOx/PG catalyst treated in the step (2), drying by microwave, heating to 110 ℃ at a heating rate of not more than 5 ℃/min, and preserving heat for 3 hours to obtain the regenerated MnOx/PG denitration catalyst.