Dry desulfurizing and denitrificating agent, and its preparation method and applications

Abstract

The present disclosure discloses a dry desulfurizing and denitrificating agent and its preparation method and applications. The desulfurizing and denitrificating agent is made of raw materials comprising the following components based on 100 parts by weight of the desulfurizing and denitrificating agent: 30-60 parts by weight of TiO.sub.2, 10-30 parts by weight of ZrO.sub.2, 2-10 parts by weight of V.sub.2O.sub.5, 2-10 parts by weight of CoO, 1-8 parts by weight of Co.sub.2O.sub.3, 2-10 parts by weight of Fe.sub.2O.sub.3, 5-15 parts by weight of MnO.sub.2, and 2-10 parts by weight of KMnO.sub.4. The desulfurizing and denitrificating agent of the present disclosure has a good catalytic oxidation performance on sulfur dioxide and nitrogen oxides of flue gas, and a high rate of desulfurization and denitrification.

Claims

1. A dry desulfurizing and denitrificating agent made of raw materials comprising the following components based on 100 parts by weight of the desulfurizing and denitrificating agent: TABLE-US-00011 TiO.sub.2 30-60 parts by weight, ZrO.sub.2 9-30 parts by weight, V.sub.2O.sub.5 2-10 parts by weight, CoO 2-10 parts by weight, Co.sub.2O.sub.3 1-8 parts by weight, Fe.sub.2O.sub.3 2-10 parts by weight, MnO.sub.2 5-15 parts by weight, and KMnO.sub.4 2-10 parts by weight.

2. The desulfurizing and denitrificating agent according to claim 1, wherein the desulfurizing and denitrificating agent is made of raw materials comprising the following components based on 100 parts by weight of the desulfurizing and denitrificating agent: TABLE-US-00012 TiO.sub.2 35-60 parts by weight, ZrO.sub.2 10-20 parts by weight, V.sub.2O.sub.5 6-10 parts by weight, CoO 2.5-7 parts by weight, Co.sub.2O.sub.3 1.5-6 parts by weight, Fe.sub.2O.sub.3 3-8 parts by weight, MnO.sub.2 6-12 parts by weight, and KMnO.sub.4 3-8 parts by weight.

3. The desulfurizing and denitrificating agent according to claim 1, wherein the desulfurizing and denitrificating agent is made of raw materials comprising the following components based on 100 parts by weight of the desulfurizing and denitrificating agent: TABLE-US-00013 TiO.sub.2 50-52 parts by weight, ZrO.sub.2 10-15 parts by weight, V.sub.2O.sub.5 8-10 parts by weight, CoO 3-6 parts by weight, Co.sub.2O.sub.3 3-5 parts by weight, Fe.sub.2O.sub.3 6-8 parts by weight, MnO.sub.2 7-9.5 parts by weight, and KMnO.sub.4 5-8 parts by weight.

4. The desulfurizing and denitrificating agent according to claim 1, wherein TiO.sub.2 and ZrO.sub.2 are used as a support; V.sub.2O.sub.5, CoO, Co.sub.2O.sub.3, Fe.sub.2O.sub.3, MnO.sub.2 and KMnO.sub.4 are used as an active component.

5. The desulfurizing and denitrificating agent according to claim 1, wherein the desulfurizing and denitrificating agent has an average particle size of 0.8-15 m.

6. A method for preparing the desulfurizing and denitrificating agent according to claim 1, comprising the following steps: (1) adding V.sub.2O.sub.5, CoO, Co.sub.2O.sub.3, Fe.sub.2O.sub.3, MnO.sub.2 and KMnO.sub.4 into a slurry containing TiO.sub.2 and ZrO.sub.2, stirring the slurry at a rotating rate of 100-300 rpm for 10-60 h, so as to obtain a mixed slurry; wherein TiO.sub.2, ZrO.sub.2, V.sub.2O.sub.5, CoO, Co.sub.2O.sub.3, Fe.sub.2O.sub.3 and MnO.sub.2 are all nano oxides; (2) adding aqueous ammonia with a concentration of 2-19 wt % into the mixed slurry under the action of ultrasonic wave with a vibration frequency of 15-200 kHz until the pH value of the reaction system reaches 7-9.5; after continuous stirring for 2-6 h, dripping potassium permanganate solution until pH value of the reaction system reaches 4-6, and continuing stirring for 2-6 h, vacuum filtrating, and water washing to obtain a paste; (3) drying the paste at 100-130 C., and grinding into small particles; calcining the small particles at 350-1000 C. for 2-6 h, so as to obtain the desulfurizing and denitrificating agent.

7. The method according to claim 6, wherein the adding rate of aqueous ammonia is 0.2-20 mL/min.

8. The method according to claim 6, wherein the dripping rate of potassium permanganate solution is 0.2-20 mL/min.

9. A method for dry desulfurization and denitrification of flue gas comprising the following steps: fully contacting flue gas with the desulfurizing and denitrificating agent according to claim 1, and then contacting with the dry absorbent powder containing magnesium oxide, so as to remove nitrogen oxides and sulfur dioxide in the flue gas; wherein the magnesium oxide contains 70-85 wt % of active magnesium oxide, and the magnesium oxide has a content of nano magnesium oxides of 10-20 wt %.

10. The method according to claim 9, wherein before contacting with the desulfurizing and denitrificating agent, the flue gas has a content of sulfur dioxide of 1000-3000 mg/nm.sup.3 and a content of nitrogen oxides of 100-600 mg/nm.sup.3, a flow velocity of 2-5 m/s, and a temperature of 110-170 C.

Description

DETAIL DESCRIPTION OF THE DISCLOSURE

(1) The present disclosure will be further explained in combination with specific embodiments, but the protection scope of the present disclosure is not limited thereto.

(2) In the present disclosure, nano refer to 1-100 nm, preferably 10-60 nm.

(3) <Dry Desulfurizing and Denitrificating Agent>

(4) The desulfurizing and denitrificating agent of the present disclosure is a desulfurizing and denitrificating catalyst. The desulfurizing and denitrificating agent may comprise a support and an active component. The support may be nano amphoteric oxides, preferably, a combination of TiO.sub.2 and ZrO.sub.2. The active component comprises nano metal oxides and KMnO.sub.4. The nano metal oxides comprise V.sub.2O.sub.5, CoO, Co.sub.2O.sub.3, Fe.sub.2O.sub.3 and MnO.sub.2. These active components are carried on the support, so as to form a desulfurizing and denitrificating agent. Coordination of these active components converts sulfur dioxide into sulfur trioxide by oxidization, and converts nitrogen oxides with low valence (NO) into NO.sub.2 and the like by catalytic oxidation. Such a combination may fully realize the catalytic oxidation, which may further improve the performance of desulfurization and denitrification.

(5) In the present disclosure, vanadium, cobalt, iron and manganese are used as active components of the desulfurizing and denitrificating agent, and present in the form of V.sub.2O.sub.5, CoO, Co.sub.2O.sub.3, Fe.sub.2O.sub.3 and MnO.sub.2, which may provide active sites for catalytic reactions, adsorb reactants of SO.sub.2 and NO, and further promote the reaction.

(6) Ti is present in the form of TiO.sub.2, which acts as the main support for active components. Ti also adsorbs NO, which increases the possibility of adsorbing reactants on the surface of the desulfurizing and denitrificating agent. When a combination of ZrO.sub.2 and TiO.sub.2 is used together as a support, Zr may occupy the sites of Ti in the original lattice, resulting in ZrTiO.sub.4. Then, the support shows new acidity and alkalinity. When SO.sub.2 and NO occupy sites of the desulfurizing and denitrificating agent, these alkaline sites may absorb SO.sub.2 and NO, resulting in occupied target sites, so as to effectively protect the active sites of active components.

(7) In accordance to one embodiment of the present disclosure, based on 100 parts by weight of the desulfurizing and denitrificating agent, the desulfurizing and denitrificating agent comprises: 30-60 parts by weight of TiO.sub.2, 9-30 parts by weight of ZrO.sub.2, 2-10 parts by weight of V.sub.2O.sub.5, 2-10 parts by weight of CoO, 1-8 parts by weight of Co.sub.2O.sub.3, 2-10 parts by weight of Fe.sub.2O.sub.3, 5-15 parts by weight of MnO.sub.2, and 2-10 parts by weight of KMnO.sub.4. Preferably, the desulfurizing and denitrificating agent comprises: 35-60 parts by weight of TiO.sub.2, 10-20 parts by weight of ZrO.sub.2, 6-10 parts by weight of V.sub.2O.sub.5, 2.5-7 parts by weight of CoO, 1.5-6 parts by weight of Co.sub.2O.sub.3, 3-8 parts by weight of Fe.sub.2O.sub.3, 6-12 parts by weight of MnO.sub.2, and 3-8 parts by weight of KMnO.sub.4. More preferably, the desulfurizing and denitrificating agent comprises: 50-52 parts by weight of TiO.sub.2, 10-15 parts by weight of ZrO.sub.2, 8-10 parts by weight of V.sub.2O.sub.5, 3-6 parts by weight of CoO, 3-5 parts by weight of Co.sub.2O.sub.3, 6-8 parts by weight of Fe.sub.2O.sub.3, 7-9.5 parts by weight of MnO.sub.2, and 5-8 parts by weight of KMnO.sub.4. It may significantly improve the oxidation performance of active components on sulfur dioxide and nitrogen oxides with low valence in flue gas by controlling the contents of active components within the above range, so as to improve the desulfurization and denitrification performance. In the present disclosure, the desulfurizing and denitrificating agent is made of raw materials comprising TiO.sub.2, ZrO.sub.2, V.sub.2O.sub.5, CoO, Co.sub.2O.sub.3, Fe.sub.2O.sub.3, MnO.sub.2 and KMnO.sub.4 above. In accordance to one preferred embodiment of the present disclosure, the desulfurizing and denitrificating agent is made of raw materials consisting of TiO.sub.2, ZrO.sub.2, V.sub.2O.sub.5, CoO, Co.sub.2O.sub.3, Fe.sub.2O.sub.3, MnO.sub.2 and KMnO.sub.4.

(8) The desulfurizing and denitrificating agent of the present disclosure has an average particle size of 0.8-15 m, preferably 1-5 m. The average particle size may be obtained by the sieving method. In the finished desulfurizing and denitrificating agent, V.sub.2O.sub.5, CoO, Co.sub.2O.sub.3, Fe.sub.2O.sub.3 and MnO.sub.2 have a particle size of 2-100 nm and a specific surface area of 100-300 m.sup.2/g.

(9) <Preparation Method>

(10) The desulfurizing and denitrificating agent of the present disclosure may be prepared with nano metal oxides. Firstly, nano metal oxides of V.sub.2O.sub.5, CoO, Co.sub.2O.sub.3, Fe.sub.2O.sub.3 and MnO.sub.2 are prepared. Common methods include sol-gel method, hydrolysis method, hydrothermal synthesis method and so on. Sol-gel method is preferred. For example, solutions of nitrates of vanadium, cobalt, iron and manganese are used as a precursor. These nitrates are hydrolyzed in the solution and condensed to sol solutions, respectively, and then converted into gels by heating and removing solvents, and finally, nano metal oxides with controllable crystal structure and particle size, and high uniformity of particle size are obtained. These methods are well known in the art, and will not be described herein.

(11) The preparation method of the present disclosure comprises (1) mixing step; (2) reaction step; (3) drying and calcining step, and the like.

(12) In the mixing step of the present disclosure, V.sub.2O.sub.5, CoO, Co.sub.2O.sub.3, Fe.sub.2O.sub.3, MnO.sub.2 and KMnO.sub.4 are added into a slurry containing TiO.sub.2 and ZrO.sub.2, and the slurry are stirred at a rotating rate of 100-300 rpm for 10-60 h, so as to obtain a mixed slurry. Preferably, the rotating rate is 200-250 rpm; the stirring time is 10-48 h. In accordance to one embodiment of the present disclosure, TiO.sub.2, ZrO.sub.2, V.sub.2O.sub.5, CoO, Co.sub.2O.sub.3, Fe.sub.2O.sub.3 and MnO.sub.2 are all nano oxides.

(13) The reaction step of the present disclosure comprises: adding aqueous ammonia with a concentration of 2-19 wt %, preferably 5-10 wt % into the mixed slurry under the action of ultrasonic wave with a vibration frequency of 15-200 kHz, preferably 50-100 kHz until pH value of the reaction system reaches 7-9.5, such as 7-8; after continuous stirring for 2-6 h, preferably 2-3 h, dripping potassium permanganate solution until pH value of the reaction system reaches 4-6, such as 5-5.5, and continuing stirring for 2-6 h, preferably 2-3 h, vacuum filtrating, and water washing to obtain a paste. The adding rate of aqueous ammonia may be 0.2-20 mL/min, preferably 3-10 mL/min; the dripping rate of potassium permanganate solution is 0.2-20 mL/min, preferably 1-5 mL/min. This is favorable to obtain nano metal oxides with uniform size. Preferably, potassium permanganate solution used in the present disclosure is acidic potassium permanganate solution.

(14) The drying and calcining step of the present disclosure comprises: drying the paste at 100-130 C., such as 105-110 C., to obtain a dried product; and grinding the dried product into small particles. Calcining the small particles at a temperature of 350-1000 C., preferably 500-800 C. for 2-6 h, such as 2-3 h, so as to obtain the desulfurizing and denitrificating agent.

(15) <Method for Dry Desulfurization and Denitrification of Flue Gas>

(16) The method for dry desulfurization and denitrification of flue gas of the present disclosure comprises a flue gas desulfurization and denitrification step. In the flue gas desulfurization and denitrification step, flue gas is fully contacted with the above desulfurizing and denitrificating agent, and then contacted with a dry absorbent powder containing magnesium oxide, so as to remove sulfur dioxide and nitrogen oxides in the flue gas.

(17) In the method of the present disclosure, the flue gas may have a content of sulfur dioxide of 1000-3000 mg/Nm.sup.3, preferably 1500-2500 mg/Nm.sup.3, more preferably 1600-2000 mg/Nm.sup.3. The flue gas may have a content of nitrogen oxides of 100-600 mg/Nm.sup.3, preferably 150-500 mg/Nm.sup.3, more preferably 300-450 mg/Nm.sup.3. The flue gas may have a content of oxygen of 10-25 vol %, preferably 15-20 vol %. The temperature may be 110-170 C.; preferably 120-135 C. In addition, the flue gas may have a flow velocity of 2-5 m/s, preferably 2.5-3.5 m/s. All the above parameters of flue gas indicate parameters of the flue gas at inlet; while parameters of the flue gas at outlet are determined according to the actual situation of desulfurization and denitrification. The above process parameters are favorable to improve the rate of desulfurization and denitrification. The flue gas is fully contacted with the desulfurizing and denitrificating agent to convert nitrogen oxides with low valence into nitrogen dioxide and the like, and convert sulfur dioxide into sulfur trioxide in the flue gas, so as to obtain pre-treated flue gas.

(18) The magnesium oxide of the present disclosure may comprise light burned magnesium oxides, micro magnesium oxides and/or nano magnesium oxides. In accordance to one embodiment of the present disclosure, the magnesium oxide comprises 70-85 wt % of active magnesium oxide, preferably 80-85% of active magnesium oxide; and the magnesium oxide has a content of nano magnesium oxide of 10-2 Owt %, preferably 15-20 wt %. Due to some unique properties of nanoparticles, the rate of desulfurization and denitrification may be improved by using nano magnesium oxides. This is more favorable to obtain magnesium nitrate and magnesium sulfate, so as to improve the effect of desulfurization and denitrification of flue gas. In the present disclosure, the absorbent may only comprise the above-mentioned magnesium oxides. The absorbent may also comprise a modifier, such as calcium oxide and silica. The modifier is a micro/nano metal oxide. In order to improve the removal efficiency, the absorbent of the present disclosure is in the form of powder. The powder may have a particle size of 0.8-15 m, preferably 1-5 m. This may directly mix the absorbent with the flue gas, so as to remove sulfur dioxide and nitrogen oxides from the flue gas. As a result, the desulfurization and denitrification of flue gas may be performed with no need of a large amount of industrial waste water, and without generating a large amount of industrial waste liquid. For example, the dry absorbent powder and the pre-treated flue gas are fully mixed in the pipeline for flue gas, and then the mixture enters the absorption tower for desulfurization and denitrification treatment. The flue gas after desulfurization and denitrification is discharged from the chimney.

Examples 1

(19) A desulfurizing and denitrificating agent was prepared according to the formula in Table 1. V.sub.2O.sub.5, CoO, Co.sub.2O.sub.3, Fe.sub.2O.sub.3, MnO.sub.2 (all of these compounds are nano metal oxides) and KMnO.sub.4 were added into a slurry containing TiO.sub.2 and ZrO.sub.2. The slurry was stirred at a rotating rate of 250 rpm for 45 h, so that a mixed slurry was obtained. Aqueous ammonia with a concentration of 10 wt % was added into the mixed slurry under the action of ultrasonic wave with a vibration frequency of 70 kHz until the pH value of the reaction reached 7; after continuous stirring for 3 h, potassium permanganate solution was added dropwise until pH value of the reaction system reached 5, and the stirring was continued for 2 h. Then the reaction was vacuum-filtrated and washed by water to obtain a paste. The adding rate of aqueous ammonia was 5 mL/min; the dripping rate of potassium permanganate solution was 2 mL/min. The paste was dried at 100 C., and ground into small particles; the small particles were calcined at 500 C. for 3 h, so as to obtain the desulfurizing and denitrificating agent H1.

(20) TABLE-US-00004 TABLE 1 The formula of the desulfurizing and denitrificating agent H1 TiO.sub.2 56.0 parts by weight, ZrO.sub.2 15.0 parts by weight, V.sub.2O.sub.5 4.0 parts by weight, CoO 5.0 parts by weight, Co.sub.2O.sub.3 5.0 parts by weight, Fe.sub.2O.sub.3 3.0 parts by weight, MnO.sub.2 7.0 parts by weight, and KMnO.sub.4 5.0 parts by weight.

(21) Catalytic oxidation was performed on flue gas with this desulfurizing and denitrificating agent. Absorption was performed with dry powder of magnesium oxides. The flue gas had a flow velocity of 2.5 m/s. Other parameters of the flue gas at inlet and parameters of the flue gas at outlet were showed in Tables 2 and 3.

(22) TABLE-US-00005 TABLE 2 Parameters of the flue gas at inlet No. Parameters Units Values 1 Flow velocity of flue gas at inlet m.sup.3/h 120000 (working conditions) 2 Flow velocity of flue gas at inlet Nm.sup.3/h 80294 (standard conditions) 3 Temperature of flue gas at inlet C. 135 4 SO.sub.2 content at inlet mg/Nm.sup.3 2000 5 Nitrogen monoxide content at inlet mg/Nm.sup.3 450 6 Humility content in the flue gas % 5.7

(23) TABLE-US-00006 TABLE 3 Parameters of the flue gas at outlet No. Items Number Units 1 Flow velocity of flue gas at outlet 42353 m.sup.3/h (working conditions) 2 Temperature of flue gas at outlet 65 C. 3 Sulfur dioxide content of 23 mg/Nm.sup.3 discharged flue gas 4 Desulfurization rate 99.51 % 5 Nitrogen oxides content of 50 mg/Nm.sup.3 discharged flue gas 6 Denitrification rate 96 % 7 Output of by-product 5.34 t/h

(24) After purification, the flue gas had a content of sulfur dioxide of 23 mg/Nm.sup.3, a content of nitrogen oxides of 50 mg/Nm.sup.3. The desulfurization rate reached 99.51%, and the denitrification rate was 96%.

Examples 2

(25) The desulfurizing and denitrificating agent H2 was prepared according to the formula in Table 4, while other conditions were the same as those in Example 1. Catalytic oxidation was performed on flue gas with this desulfurizing and denitrificating agent. Absorption was performed with dry powder of magnesium oxides. Parameters of the flue gas at inlet were the same as those in Example 1. Parameters of the flue gas at outlet were showed in Table 5.

(26) TABLE-US-00007 TABLE 4 The formula of the desulfurizing and denitrificating agent H2 TiO.sub.2 52.0 parts by weight, ZrO.sub.2 15.0 parts by weight, V.sub.2O.sub.5 6.0 parts by weight, CoO 5.0 parts by weight, Co.sub.2O.sub.3 5.0 parts by weight, Fe.sub.2O.sub.3 5.0 parts by weight, MnO.sub.2 7.0 parts by weight, and KMnO.sub.4 5.0 parts by weight.

(27) TABLE-US-00008 TABLE 5 Parameters of the flue gas at outlet No. Items Number Units 1 Flow velocity of flue gas at outlet 41341 m.sup.3/h (working conditions) 2 Temperature of flue gas discharged 65 C. 3 Sulfur dioxide content of 19 mg/Nm.sup.3 discharged flue gas 4 Desulfurization rate 99.60 % 5 Nitrogen oxides content of 43 mg/Nm.sup.3 discharged flue gas 6 Denitrification rate 96.02 % 7 Output of by-product 5.43 t/h

(28) After purification, the flue gas had a content of sulfur dioxide of 19 mg/Nm.sup.3, a content of nitrogen oxides of 43 mg/Nm.sup.3. The desulfurization rate reached 99.60%, and the denitrification rate was 96.02%.

Examples 3

(29) The desulfurizing and denitrificating agent H3 was prepared according to the formula in Table 6, while other conditions were the same as those in Example 1. Catalytic oxidation was performed on flue gas with this desulfurizing and denitrificating agent. Absorption was performed with dry powder of magnesium oxides. Parameters of the flue gas at inlet were the same as those in Example 1. Parameters of the flue gas at outlet were showed in Table 7.

(30) TABLE-US-00009 TABLE 6 The formula of the desulfurizing and denitrificating agent H3 TiO.sub.2 48.0 parts by weight, ZrO.sub.2 15.0 parts by weight, V.sub.2O.sub.5 8.0 parts by weight, CoO 5.0 parts by weight, Co.sub.2O.sub.3 5.0 parts by weight, Fe.sub.2O.sub.3 7.0 parts by weight, MnO.sub.2 7.0 parts by weight, and KMnO.sub.4 5.0 parts by weight.

(31) TABLE-US-00010 TABLE 7 Parameters of the flue gas at outlet No. Items Number Units 1 Flow velocity of flue gas at outlet 40324 m.sup.3/h (working conditions) 2 Temperature of flue gas discharged 65 C. 3 Sulfur dioxide content of 13 mg/Nm.sup.3 discharged flue gas 4 Desulfurization rate 99.73 % 5 Nitrogen oxides content of 29 mg/Nm.sup.3 discharged flue gas 6 Denitrification rate 97.39 % 7 Output of by-product 5.7 t/h

(32) After purification, the flue gas had a content of sulfur dioxide of 13 mg/Nm.sup.3, a content of nitrogen oxides of 29 mg/Nm.sup.3. The desulfurization rate reached 99.73%, and the denitrification rate was 97.39%.

(33) The present disclosure is not limited by the above embodiments. Any variation, modification and replacement to the disclosed embodiments which are apparent to those skilled in the art and do not depart from the essence of the present disclosure fall in the scope of the present disclosure.