PREPARATION METHOD FOR ACTIVATED COKE CATALYST CAPABLE OF SIMULTANEOUSLY REMOVING NO, SO2 AND HCl

Abstract

The present invention discloses a preparation method for an activated coke catalyst capable of simultaneously removing NO, SO.sub.2, and HCl. The method includes: step 1: crushing and sieving activated coke to obtain coke particles with a particle size of 40-60 microns; step 2: putting the activated coke in an oxidizing agent, stirring at 80 C. for 8 h to allow for a thorough mixing and reaction, washing the activated coke obtained after the reaction until a neutral pH is reached, and drying to obtain activated coke with oxygen-containing functional groups; and step 3: impregnating, by equivalent-volume impregnation, the activated coke with oxygen-containing functional groups obtained in step 2 with a copper nitrate trihydrate aqueous solution for 24 h, drying, and putting the activated coke in a resistance furnace, and introducing argon for calcination to obtain the activated coke catalyst capable of simultaneously removing NO, SO.sub.2, and HCl.

Claims

1. A preparation method for an activated coke catalyst capable of simultaneously removing NO, SO.sub.2, and HCl, comprising: step 1: crushing and sieving activated coke to obtain coke particles with a particle size of 40-60 microns; step 2: putting the activated coke in an oxidizing agent, stirring at 80 C. for 8 h to allow for a thorough mixing and reaction, washing the activated coke obtained after the reaction until a neutral pH is reached, and drying to obtain activated coke with oxygen-containing functional groups; and step 3: impregnating, by equivalent-volume impregnation, the activated coke with oxygen-containing functional groups obtained in step 2 with a copper nitrate trihydrate aqueous solution for 24 h, drying, and putting the activated coke in a resistance furnace, and introducing argon for calcination to obtain the activated coke catalyst capable of simultaneously removing NO, SO.sub.2, and HCl.

2. The preparation method for an activated coke catalyst capable of simultaneously removing NO, SO.sub.2, and HCl according to claim 1, wherein in step 1, the oxidizing agent is 65% nitric acid with a concentration of 3 mol/L to 5 mol/L.

3. The preparation method for an activated coke catalyst capable of simultaneously removing NO, SO.sub.2, and HCl according to claim 1, wherein in step 1, a mass ratio of the activated coke to the oxidizing agent is 1: (5-15).

4. The preparation method for an activated coke catalyst capable of simultaneously removing NO, SO.sub.2, and HCl according to claim 1, wherein in step 2, a volume content of the copper (II) nitrate trihydrate aqueous solution is 5.4 ml/g to 12.6 ml/g based on mass of activated coke.

5. The preparation method for an activated coke catalyst capable of simultaneously removing NO, SO.sub.2, and HCl according to claim 1, wherein in step 2, an amount of CuO supported on the final activated coke catalyst is 3 wt % to 7 wt %.

6. The preparation method for an activated coke catalyst capable of simultaneously removing NO, SO.sub.2, and HCl according to claim 1, wherein in step 2, the catalyst is calcined at 300 C. for 2 h under an argon atmosphere.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

Example 1

[0019] Activated coke was put in 3 mol/L of 65% nitric acid, and stirred at 80 C. for 8 h to allow for a thorough mixing and reaction, the activated coke obtained after the reaction was washed until a neutral pH is reached, and drying was conducted at 105 C. for 12 h to obtain activated coke with oxygen-containing functional groups. Then 10 g of activated coke with oxygen-containing functional groups was impregnated with 54 mL of copper (II) nitrate trihydrate aqueous solution for 24 h, dried at 105 C. for 12 h, and then put in a resistance furnace and calcined at 300 C. for 2 h to obtain the catalyst.

Embodiment 2

[0020] Activated coke was put in 4 mol/L of 65% nitric acid, and stirred at 80 C. for 8 h to allow for a thorough mixing and reaction, the activated coke obtained after the reaction was washed until a neutral pH is reached, and drying was conducted at 105 C. for 12 h to obtain activated coke with oxygen-containing functional groups. Then 10 g of activated coke with oxygen-containing functional groups was impregnated with 90 mL of copper (II) nitrate trihydrate aqueous solution for 24 h, dried at 105 C. for 12 h, and then put in a resistance furnace and calcined at 300 C. for 2 h to obtain the catalyst.

Embodiment 3

[0021] Activated coke was put in 5 mol/L of 65% nitric acid, and stirred at 80 C. for 8 h to allow for a thorough mixing and reaction, the activated coke obtained after the reaction was washed until a neutral pH is reached, and drying was conducted at 105 C. for 12 h to obtain activated coke with oxygen-containing functional groups. Then 10 g of activated coke with oxygen-containing functional groups was impregnated with 126 mL of copper (II) nitrate trihydrate aqueous solution for 24 h, dried at 105 C. for 12 h, and then put in a resistance furnace and calcined at 300 C. for 2 h to obtain the catalyst.

Comparative Example 1

[0022] The difference between Comparative Example 1 and Example 2 lies in that activated coke was put in 1 mol/L of 65% nitric acid for a mixing and reaction, while contents not mentioned in this example were the same as those in Example 2.

Comparative Example 2

[0023] The difference between Comparative Example 2 and Example 3 lies in that 20 g of activated coke with oxygen-containing functional groups was impregnated with 144 mL of copper (II) nitrate trihydrate aqueous solution for 24 h, while contents not mentioned in this example were the same as those in Example 2.

Comparative Example 3: Unmodified Activated Coke Catalyst that is Available on the Market

Performance Evaluation:

[0024] Testing condition: The modified activated coke sample prepared in the example was put in a quartz tube reactor, and the reactor was then put in a tube furnace with the temperature adjusted to 180 C. A mixed gas of SO.sub.2, HCl and NO with a total gas flow rate of 1 L/min was introduced into the reactor, and concentration changes of HCl, SO.sub.2 and NO were monitored in real time using a Fourier infrared spectrometer. The desulfuration, dechlorination and denitration efficiency was tested. Test results were shown in Table 1.

TABLE-US-00001 TABLE 1 Comparison of catalytic performance between Examples 1-3 and Comparative Examples 1-3 Desulfuration Dechlorination Denitration Catalyst preparation efficiency efficiency efficiency Example 1 3 mol/L of 65% nitric 78.2% 79.6% 76.3% acid + 54 mL of copper (II) nitrate trihydrate aqueous solution Example 2 4 mol/L of 65% nitric 84.8% 85.2% 82.5% acid + 90 mL of copper (II) nitrate trihydrate aqueous solution Example 3 5 mol/L of 65% nitric 90.7% 95.2% 97.1% acid + 126 mL of copper (II) nitrate trihydrate aqueous solution Comparative 1 mol/L of 65% nitric 63.6% 74.1% 71.4% Example 1 acid + 54 mL of copper (II) nitrate trihydrate aqueous solution Comparative 5 mol/L of 65% nitric 69.4% 66.2% 55.6% Example 2 acid + 144 mL of copper (II) nitrate trihydrate aqueous solution Comparative Unmodified activated 54.0% 56.2% 48.7% Example 3 coke

[0025] As can be seen from experimental results in Table 1, Experimental Examples 1-3 all achieve great improvements in desulfuration efficiency, dechlorination efficiency and denitration efficiency compared with Comparative Example 3. The principle is as follows: in the present invention, the content of oxygen-containing functional groups on the surface of the activated coke is increased by modifying the activated coke with nitric acid, and CuO is supported on the activated coke. Compared with the unmodified activated coke in Comparative Example 3, the catalyst in the present invention has rich oxygen-containing functional groups, and the oxygen-containing functional groups can promote the removal of SO.sub.2, thereby improving the desulfuration efficiency. The CuO supported on the activated coke can completely react with HCl in flue gas to form a hydroxychloride intermediate which is then converted into Cl.sub.2 for dechlorination. On copper-based catalysts, CO can replace NH.sub.3 as a reducing gas to react with NO, which solves the problem of denitration catalyst deterioration caused by the formation of NH.sub.4Cl, thereby improving the denitration efficiency.

[0026] Compared with Experimental Example 1, the concentration of nitric acid used in Comparative Example 1 is 1 mol/L, which is relatively low. The purpose of nitric acid modification is to increase the content of oxygen-containing functional groups (such as carboxyl and carbonyl groups) on the surface of activated coke. These oxygen-containing functional groups on the surface play an important role in the desulfuration reaction, and with the increase of the content of oxygen-containing functional groups, the desulfuration efficiency is improved accordingly. When nitric acid with different concentrations is used for modification, the content of oxygen-containing functional groups increases differently, and oxygen-containing functional groups are increased with an appropriate concentration. Therefore, Example 1 achieves a better desulfuration effect than Comparative Example 1.

[0027] Compared with Example 3, in Comparative Example 2, the amount of copper (II) nitrate trihydrate aqueous solution used is different, resulting in a different amount of CuO supported on the activated coke. The supported CuO provides new active sites for dechlorination. HCl in the flue gas can completely react with CuO to form a hydroxychloride intermediate which acts as a transporter for chlorine atoms present on the catalyst surface, and the chlorine atoms are then converted into Cl.sub.2 to be released. Meanwhile, during the denitration process, on a copper-based catalyst, CO in flue gas can replace NH.sub.3 as a reducing gas to react with NO, which avoids ammonium salt deposition on the catalyst, thereby improving the denitration efficiency. However, in Comparative Example 2, the excessively supported CuO can lead to the blockage of micropores in the activated coke, resulting in a decrease in the micropore volume and a reduction in the number of active sites on the activated coke. This reduces the amount of SO.sub.2, HCl, and NO gas that are absorbed, which in turn lowers the desulfuration, dechlorination, and denitration efficiency.

[0028] The foregoing descriptions are merely preferred specific embodiments of the present invention, but are not intended to limit the protection scope of the present invention. Any equivalent replacement or variation made by a person skilled in the art according to the technical solutions of the present invention and the inventive concept thereof within the technical scope disclosed in the present invention shall fall within the protection scope of the present invention.