Preparation method of zinc oxide for deep desulfurization of co-rich gas at normal temperature and application process thereof

Abstract

The application discloses a zinc oxide preparation method for CO-rich gas normal-temperature deep fine desulfurization and application process thereof, and adopts a mixed loading combination process of a deoxidizing agent, primary zinc oxide, a hydrolysis agent and secondary zinc oxide to solve the problems of COS release and insufficient deep fine desulfurization precision of CO-rich gas normal-temperature deep fine desulfurization. The primary zinc oxide is obviously acidic, and the desulfurization is not affected by acidic gases such as CO2 in the gas; the secondary zinc oxide is obviously alkaline, and has high desulfurization precision and large sulfur capacity; the process can be used for deep fine desulfurization of raw gas in projects such as production of methanol, LNG and ethylene glycol from calcium carbide furnace tail gas, converter gas, blast furnace gas and coke oven gas, etc., fundamentally solves the problem of COS release, has high desulfurization precision and a long service period.

Description

Technical Field

[0001] This invention relates to a method for preparing zinc oxide for deep desulfurization of CO-rich gas at room temperature and its application process. It is particularly applicable to the method for preparing zinc oxide for deep desulfurization of raw materials for projects producing methanol, LNG, ethylene glycol, etc. from CO-rich gases such as calcium carbide furnace tail gas, converter gas, blast furnace gas, and coke oven gas. Background Technology

[0002] Currently, projects using CO-rich gases such as calcium carbide furnace tail gas, converter gas, blast furnace gas, and coke oven gas to produce methanol, LNG, and ethylene glycol have been put into operation due to their significant economic and social benefits from resource recycling. One of the key aspects of this technology is the purification of the feed gas, particularly the deep removal of sulfides. This is because the synthesis catalysts used in methanol, LNG, and ethylene glycol production have active components of Cu, Ni, and Cu, respectively, which readily react with sulfides and become permanently deactivated. Existing desulfurization processes typically employ TSA or wet coarse desulfurization, followed by a fine desulfurization process. This involves hydrolysis or hydrogenation to convert organic sulfur, with activated carbon or iron, manganese, zinc, etc., absorbing the generated H2S. This process usually involves two or more stages of treatment, with the total sulfur content at the fine desulfurization outlet generally below 0.1 ppm. Taking methanol synthesis catalysts as an example, conducting deep desulfurization after fine desulfurization can reduce the total sulfur in the synthesis gas from 0.1 ppm to below 10 ppb, extending the lifespan of the methanol catalyst from 2-3 years to 5-6 years. This reduces the need for catalyst replacement by one time between two major overhaul cycles, generating over 20 million yuan in benefits annually for a methanol production enterprise with an annual output of 1 million tons. Therefore, conducting deep desulfurization is highly significant.

[0003] Compared to the medium-temperature desulfurization bed composite metal oxide ultrafine desulfurization, zinc oxide room temperature deep fine desulfurization has the advantages of not requiring long-term reduction and activation treatment before use, being ready to use immediately after installation, not requiring heating during use, saving energy and reducing consumption, and having greater flexibility in process matching.

[0004] In their paper "Analysis of Sulfur Release Phenomenon and Causes in Dry Desulfurization," Guo Hanxian et al. mentioned that a methanol plant had adopted a two-stage low-temperature hydrolysis followed by room-temperature zinc oxide desulfurization process for decarbonization. The result was that room-temperature zinc oxide exhibited COS release. However, when the temperature was increased to 180℃~210℃, the sulfur release disappeared. They pointed out that research on COS release in desulfurization beds of zinc oxide and other metal oxides is still insufficient, and no solution to the problem of room-temperature zinc oxide COS release has been provided. The inventors also discovered the phenomenon of room-temperature zinc oxide COS release in their research on CO-rich gases such as calcium carbide furnace tail gas, converter gas, and blast furnace gas.

[0005] In addition, according to conservative estimates, the annual consumption of zinc oxide desulfurizer in China is over 40,000 tons. These desulfurizers will become deactivated after a certain period of use. Researching the recycling of deactivated zinc oxide is not only of environmental significance but also of great economic value.

[0006] The pulverized, deactivated ZnO desulfurizing agent undergoes a calcination treatment, the main chemical reaction of which is as follows: ZnS + 2O2 = ZnSO4 (1) ZnS + 3ZnSO4= 3ZnO + 4SO2↑ (2) 2SO2 + O2 = 2SO3 (3) ZnSO4 = ZnO + SO3↑ (4) Below 600℃, reaction (1) is the main reaction; above 600℃, reaction (2) occurs; and above 750℃, reaction (4) is the main reaction. The inventors found that ZnO obtained by roasting above 600℃ and above 750℃ does not have desulfurization activity. On the contrary, ZnSO4 generated by roasting below 600℃ can withstand CO2 desulfurization at room temperature, but it will release COS when used for CO-rich gas desulfurization.

[0007] Patents CN104307318A, CN101485954A, and CN104307318A disclose preparation methods that all involve adding copper to improve the desulfurization precision and room-temperature sulfur capacity of zinc oxide. The research focuses on how to solve the problem of uniform dispersion through the preparation process. However, none of these zinc oxide patents address the issue of COS release during use in CO-rich gas environments, nor do they address the recycling of deactivated zinc oxide. Summary of the Invention

[0008] The purpose of this invention is to provide a method for preparing zinc oxide for deep, room-temperature fine desulfurization of CO-rich gas and its application process, fundamentally solving the problem of CO release, achieving high desulfurization accuracy and long service life. Another purpose of this invention is to provide the above-mentioned two-stage zinc oxide preparation method for deep, room-temperature fine desulfurization of CO-rich gas, and to recover and utilize deactivated zinc oxide.

[0009] The technical solution adopted by this invention to solve its technical problem is as follows: a mixed combination process of deoxidizer, primary zinc oxide, hydrolysant, and secondary zinc oxide is used to solve the problems of COS emission and insufficient precision in deep fine desulfurization of CO-rich gas at room temperature. The gas enters from the top and exits from the bottom, and the desulfurization tower contains, from top to bottom, deoxidizer, primary zinc oxide, hydrolysant, and secondary zinc oxide.

[0010] The deoxidizer mentioned is CuSi / C, which can react with CO to convert oxygen in CO-rich gases such as calcium carbide furnace tail gas, converter gas, and blast furnace gas into CO2, thus removing the oxygen. The chemical equation for the reaction is as follows: 2CO + O2 = 2CO2 Even if upstream operations in the desulfurization process, such as hydrogenation, remove oxygen, the CO-rich gas entering the deep desulfurization stage may still contain oxygen at levels in the ppm range. The purpose of deoxygenation is twofold: first, to suppress the release of COS from zinc oxide. Data shows that under relatively low temperatures, the reaction principle of COS release from CO-rich gas is: CO + S = COS. Deoxygenation can suppress the formation of elemental sulfur, thereby suppressing the release of COS from zinc oxide; second, to protect the third layer of hydrolysis catalyst. Oxygen can react with H2S to produce elemental sulfur, leading to sulfur deposition that blocks the catalyst pores and deactivates the hydrolysis catalyst at room temperature.

[0011] The primary zinc oxide is composed of ZnO, desulfurized and deactivated ZnO, and Zn(NO3). 2、 It is obtained from starch, etc. Primary zinc oxide is obtained by recycling deactivated zinc oxide and calcining it at a temperature below 600℃ to produce ZnSO4. The resulting primary zinc oxide is acidic and its desulfurization is unaffected by acidic gases such as CO2 in the gas, allowing it to withstand CO2 desulfurization at room temperature. However, it will release COS when used for CO-rich gas desulfurization. As primary zinc oxide, the COS-releasing reaction can also consume the oxygen that has not been removed by the upper deoxidizer, protecting the hydrolysis catalyst while ensuring that secondary zinc oxide does not release COS. The preparation method of primary zinc oxide includes the following steps: (1) Mix ZnO powder, desulfurized and deactivated ZnO and starch in a mass ratio of (2.5~6.2):(3.5~7.0):(0.3~0.5), grind evenly, add an appropriate amount of deionized water, stir and press evenly, extrude into shape, place for 4 hours, dry at 115~140℃ for 2.5~3.5 hours, and then calcine at 400~600℃ for 5~7 hours to obtain the primary zinc oxide precursor.

[0012] (2) Prepare an 8%~15% Zn(NO3)2 solution, adjust its pH value to 4.8~6.2 with a 6%~13% nitric acid solution, saturate and impregnate the primary zinc oxide precursor for 30min~70min, and dry it at 115~135℃ for 3~4h to obtain primary zinc oxide for deep fine desulfurization of CO-rich gas at room temperature.

[0013] While CuSi / C deoxidizers may release COS during deoxidation, primary zinc oxide used for CO-rich desulfurization also releases COS, but it can also consume the oxygen required for COS release. This allows the COS release reaction to occur before hydrolysis, where the hydrolysis catalyst converts the generated COS into H2S. Then, the hydrolysis agent can also consume the oxygen required for COS release. Thus, after hydrolysis, secondary zinc oxide only removes a small amount of H2S load and basically does not release COS.

[0014] The hydrolysing agent is an Al2O3-TiO2 composite carrier loaded with 5%~15% K2CO3. This hydrolysing agent is used for room temperature COS hydrolysis and conversion, and can remove COS to below 8 ppb.

[0015] The secondary zinc oxide is prepared from ZnO, basic zinc carbonate, nano-lime, and volcanic rock. The preparation method includes the following steps: (1) Mix ZnO powder, basic zinc carbonate, nano lime and crushed volcanic rock in a mass ratio of (2.0~3.2):(1.8~3.0):(2.9~3.7):(1.3~2.1), grind them evenly, add an appropriate amount of deionized water, stir and press evenly, extrude and shape, and keep moist for 12h~24h.

[0016] (2) After moisturizing, dry at 115℃~135℃ for 3h~4h, cool and then load into the tower, and introduce a space velocity of 300~1000h. -1 After nitrogen purging for 10-20 hours, the product is unpacked, sealed in bags, and used for deep fine desulfurization at room temperature in CO-rich gas environment, resulting in secondary zinc oxide.

[0017] The volume ratio of the deoxidizer, primary zinc oxide, hydrolysant, and secondary zinc oxide is (0.5~2.0):(3.0~4.5):(1.2~2.5):(2.5~3.8).

[0018] The beneficial effects of this invention are: (1) Multi-stage deep deoxidation fundamentally solves the COS emission problem. Gases rich in CO, such as those from calcium carbide furnaces, converters, and blast furnaces, have complex compositions. After initial treatment in the desulfurization process, deep desulfurization at room temperature requires reducing total sulfur from 0.1 ppm to below 10 ppb. Compared to ppb-level sulfides, the content of CO, CO2, water vapor, H2, and O2 in these gases is thousands or even tens of millions of times higher. This means the concentration of reactants in the COS emission side reaction is excessively large, and simply improving the ZnO formulation and manufacturing process is insufficient to solve the COS emission problem. Data shows that under low-temperature conditions, the reaction principle of COS emission in CO-rich gas is: CO + S = COS. Deoxidation can inhibit the formation of elemental sulfur, thereby inhibiting zinc oxide COS emission. This invention employs a mixed combination process of deoxidizer, primary zinc oxide, hydrolysate, and secondary zinc oxide, fundamentally solving the COS emission problem. The solution involves the following three points: First, multi-stage deep deoxidation. The gas passes through a deoxidizer, primary zinc oxide, and hydrolyzing agent sequentially from top to bottom. The CuSi / C deoxidizer consumes CO at room temperature for deoxygenation, constituting primary deoxygenation. Primary zinc oxide, used for CO-rich gas desulfurization, releases COS, but also consumes the oxygen required for COS release, equivalent to secondary deoxygenation. The hydrolyzing agent's poisoning side reaction also consumes oxygen, equivalent to tertiary deoxygenation. This effectively ensures that the gas entering the secondary zinc oxide is essentially oxygen-free, thus achieving the goal of no COS release from the secondary zinc oxide. Secondly, since trace amounts of COS release are unavoidable, the COS release reaction is made to occur before hydrolysis, and then the hydrolysis catalyst converts the COS into H2S. The primary zinc oxide in this invention is an acidic zinc oxide that releases COS during CO-rich gas desulfurization. The aim is to ensure that the COS release reaction proceeds fully before hydrolysis, thereby consuming the trace components such as oxygen required for COS release and ensuring that the secondary zinc oxide after hydrolysis does not release COS. Third, secondary zinc oxide is alkaline. After multiple stages of deoxidation and desulfurization, secondary zinc oxide only removes a small amount of H2S load and basically does not release COS.

[0019] (2) Recycling deactivated zinc oxide. As mentioned earlier, it is conservatively estimated that the annual consumption of zinc oxide desulfurizer in China is over 40,000 tons. These desulfurizers will become deactivated after a certain period of use. Researching the recycling of deactivated zinc oxide is not only of environmental significance but also of great economic value.

[0020] The pulverized, deactivated ZnO desulfurizing agent undergoes a calcination treatment, the main chemical reaction of which is as follows: ZnS + 2O2 = ZnSO4 (1) ZnS + 3ZnSO4= 3ZnO + 4SO2↑ (2) 2SO2 + O2 = 2SO3 (3) ZnSO4 = ZnO + SO3↑ (4) Below 600℃, reaction (1) is dominant; above 600℃, reaction (2) occurs; and above 750℃, reaction (4) is dominant. The inventors found that ZnO obtained by roasting above 600℃ and above 750℃ does not have desulfurization activity. On the contrary, ZnSO4 generated by roasting below 600℃ can withstand CO2 desulfurization at room temperature. However, it will release COS when used for CO-rich gas desulfurization. The inventors innovatively turned this defect into an advantage and used it as the primary zinc oxide in the CO-rich gas room temperature deep fine desulfurization process. This allows the COS release reaction to proceed fully before hydrolysis, which also consumes the trace components such as oxygen required for COS release, ensuring that the secondary zinc oxide after hydrolysis does not release COS. By adopting a mixed combination process of deoxidizer, primary zinc oxide, hydrolysant, and secondary zinc oxide, the problem of COS release is not only fundamentally solved, but also the problem of recycling deactivated zinc oxide is solved.

[0021] (3) High desulfurization precision and long service life. Gases rich in CO, such as calcium carbide furnace tail gas, converter gas, and blast furnace gas, often contain CO2. CO2 is an acidic oxide and will compete with H2S for adsorption on the desulfurizing agent, reducing the sulfur capacity of zinc oxide desulfurization and the precision of H2S removal. This invention recycles deactivated zinc oxide and calcines it at a temperature below 600℃ to generate ZnSO4. The resulting primary zinc oxide is acidic and its desulfurization is unaffected by acidic gases such as CO2 in the gas. It can withstand CO2 desulfurization at room temperature, achieving high-precision removal of H2S, although some H2S is converted back to COS. The lower layer hydrolysant is an Al2O3-TiO2 composite carrier loaded with 5%~15% K2CO3, used for room-temperature COS hydrolysis conversion, which can remove COS to below 8 ppb. Secondary zinc oxide is alkaline. Even though CO2 interferes with its desulfurization activity, it only removes a small amount of H2S load from hydrolysis. Furthermore, the upper layer contains a deoxidizer equivalent to tertiary deoxidation, primary zinc oxide, and a hydrolysate, ensuring that the gas entering the secondary zinc oxide layer is essentially oxygen-free. This results in minimal COS release from the secondary zinc oxide layer. Therefore, this process can achieve a deep, fine desulfurization effect at room temperature with a total sulfur content of less than 10 ppb. Conventional zinc oxide desulfurizers, even high-quality zinc oxide uniformly dispersed with copper, may offer high removal accuracy and long service life for fine desulfurization of gases like H2 and N2. However, in CO-rich gases such as calcium carbide furnace tail gas, converter gas, and blast furnace gas, not only does CO2 interfere with desulfurization, but it also reverses and generates COS. Pure zinc oxide struggles to achieve a total sulfur content of less than 10 ppb in these complex gas environments. The combined process of the acidic primary zinc oxide and alkaline secondary zinc oxide in this invention overcomes this drawback, achieving high desulfurization accuracy and a long service life.

[0022] (4) Green Economy. Patents CN104307318A, CN101485954A, and CN104307318A disclose methods for preparing high-quality zinc oxide, but these processes are complex, especially in achieving nanoscale dispersion. This not only results in high equipment investment costs but also generates significant amounts of waste. Furthermore, metals such as copper are hazardous waste; while copper doping improves desulfurization activity, the disposal of deactivated zinc oxide is difficult. This process, however, offers simple methods for preparing primary and secondary zinc oxide, eliminating precipitation and co-precipitation operations, and resulting in low production costs. The deactivated zinc oxide can be recycled as a raw material for primary zinc oxide. Detailed Implementation

[0023] The invention will now be described in further detail with reference to specific experimental procedures. However, the rights of the invention are not limited to the following embodiments. In the following embodiments, all percentage contents refer to mass percentages.

[0024] Example 1 A family in Ningxia with 100,000 Nm 3 / h coke oven gas to LNG chemical plant, desulfurization tower filling capacity 50m 3 From top to bottom, they are 2.5m each. 3 Deoxidizer, 22.5m 3 Grade 1 zinc oxide, 6m 3 Hydrolysate, 19m 3 Secondary zinc oxide, with a volume ratio of 0.5:4.5:1.2:3.8. Of which 22.5m... 3 The preparation process of primary zinc oxide is as follows: (1) Mix 15.07 tons of ZnO powder, 8.51 tons of desulfurized and deactivated ZnO and 0.75 tons of starch in a mass ratio of 6.2:3.5:0.3. Add an appropriate amount of deionized water, stir and grind evenly, extrude and shape, let stand for 4 hours, dry at 115℃ for 3.5 hours, and then calcine at 400℃ for 7 hours to obtain the first-grade zinc oxide precursor.

[0025] (2) Prepare an 8% Zn(NO3)2 solution, adjust its pH to 6.2 using a 6% nitric acid solution, and saturate it with the primary zinc oxide precursor for 30 min. After drying at 115℃ for 4 h, 25.2 tons of primary zinc oxide (volume 22.5 m³) are obtained. 3 ).

[0026] Required 19m 3 The preparation process of secondary zinc oxide is as follows: (1) Mix 4.1 tons of ZnO powder, 6.15 tons of basic zinc carbonate, 5.94 tons of nano lime and 4.31 tons of crushed volcanic rock in a mass ratio of 2.0:3.0:2.9:2.1. Add an appropriate amount of deionized water, stir and grind evenly, then extrude into shape and keep moist for 12 hours.

[0027] (2) After moisturizing, dry at 115℃ for 4 hours, cool and then load into the tower, and introduce air at a space velocity of 300 h⁻¹. -1 After nitrogen purging for 20 hours, 20.5 tons of secondary zinc oxide (volume 19m³) were obtained by unloading, bagging, and sealing. 3 ).

[0028] Operating airspeed is 2000h -1 It has been running for half a year, and the total sulfur content in exports is less than 10 ppb.

[0029] Example 2 A Shanxi company with 80,000 Nm 3 / h converter gas to ethylene glycol chemical plant, desulfurization tower loading capacity 80m 3 , from top to bottom, 16m 3 Deoxidizer, 24m 3 Grade 1 zinc oxide, 20m 3 Hydrolysate, 20m 3 Secondary zinc oxide, with a volume ratio of 2.0:3.0:2.5:2.5. Of which 24m 3 The preparation process of primary zinc oxide is as follows: (1) Mix 6.0 tons of ZnO powder, 16.79 tons of desulfurized and deactivated ZnO and 1.2 tons of starch in a mass ratio of 2.5:7.0:0.5, add an appropriate amount of deionized water, stir and grind evenly, extrude and shape, place for 4 hours, dry at 140℃ for 2.5 hours, and then calcine at 600℃ for 5 hours to obtain the primary zinc oxide precursor.

[0030] A 15% Zn(NO3)2 solution was prepared, and its pH was adjusted to 4.8 using a 13% nitric acid solution. The primary zinc oxide precursor was then saturated and impregnated for 70 minutes. After drying at 135℃ for 3 hours, 26.4 tons (24m³) of primary zinc oxide were obtained. 3 ).

[0031] Required 20m 3 The preparation process of secondary zinc oxide is as follows: (1) Mix 6.97 tons of ZnO powder, 3.92 tons of basic zinc carbonate, 8.06 tons of nano lime and 2.84 tons of crushed volcanic rock in a mass ratio of 3.2:1.8:3.7:1.3, add an appropriate amount of deionized water, stir and grind evenly, extrude into shape, and keep moist for 24 hours.

[0032] (2) After moisturizing, dry at 135℃ for 3 hours, cool and then load into the tower, and introduce air at a space velocity of 1000 h⁻¹. -1 After nitrogen purging for 10 hours, 21.8 tons (20m³) of secondary zinc oxide were obtained by unloading, sealing, and packaging. 3 ).

[0033] Operating airspeed is 1000h -1 It has been in operation for a year, and the total sulfur content in exports is less than 9 ppb.

[0034] Example 3 A company in Inner Mongolia with a capacity of 50,000 Nm 3 A methanol production plant using calcium carbide furnace tail gas has a desulfurization tower with a loading capacity of 100m³. 3 , from top to bottom, 12m 3 Deoxidizer, 38m 3 Grade 1 zinc oxide, 18m 3 Hydrolysate, 32m 3 Secondary zinc oxide, with a volume ratio of 1.2:3.8:1.8:3.2. Of which 38m 3 The preparation process of primary zinc oxide is as follows: (1) 12.98 tons of ZnO powder, 22.62 tons of desulfurized and deactivated ZnO and 1.49 tons of starch were mixed in a mass ratio of 3.5:6.1:0.4. An appropriate amount of deionized water was added, and the mixture was stirred, crushed and extruded into shape. After being placed for 4 hours, it was dried at 130℃ for 3.0 hours and then calcined at 500℃ for 6 hours to obtain the primary zinc oxide precursor.

[0035] A 10% Zn(NO3)2 solution was prepared, and its pH was adjusted to 5.5 using a 10% nitric acid solution. The primary zinc oxide precursor was then saturated and impregnated for 50 minutes. After drying at 120℃ for 3.5 hours, 39.9 tons of primary zinc oxide (volume 38m³) were obtained. 3 ).

[0036] Required 32m 3 The preparation process of secondary zinc oxide is as follows: (1) Mix 10.56 tons of ZnO powder, 7.04 tons of basic zinc carbonate, 11.26 tons of nano lime and 6.34 tons of crushed volcanic rock in a mass ratio of 3.0:2.0:3.2:1.8, add an appropriate amount of deionized water, stir and grind evenly, extrude into shape, and keep moist for 24 hours.

[0037] (2) After moisturizing, dry at 125℃ for 3.5h, cool and then load into the tower, and introduce air at 600h h⁻¹. -1 After nitrogen purging for 15 hours, 35.2 tons (32m³) of secondary zinc oxide were obtained by unloading, bagging, and sealing. 3 ).

[0038] Operating airspeed is 500 h -1 It has been operating for ten months, and the total sulfur content in exports is less than 8 ppb.

Claims

1. A zinc oxide for use in a CO-rich, ambient-temperature deep desulfurization process, characterized in that: Gas enters from top and exits from bottom; the desulfurization tower contains, from top to bottom, deoxidizer, primary zinc oxide, hydrolysant, and secondary zinc oxide. The deoxidizer mentioned is a CuSi / C CO-consuming room temperature deoxidizer; The hydrolysate carrier is an Al2O3-TiO2 composite carrier; The primary zinc oxide is prepared from ZnO, desulfurized and deactivated ZnO, Zn(NO3)2, and starch; the preparation method of primary zinc oxide includes the following steps: (1) Mix ZnO powder, desulfurized and deactivated ZnO and starch in a mass ratio of (2.5~6.2):(3.5~7.0):(0.3~0.5), grind evenly, add an appropriate amount of deionized water, stir and press evenly, extrude into shape, place for 4 hours, dry at 115~140℃ for 2.5~3.5 hours, and then calcine at 400~600℃ for 5~7 hours to obtain the primary zinc oxide precursor; (2) Prepare an 8%~15% Zn(NO3)2 solution, adjust its pH value to 4.8~6.2 with a 6%~13% nitric acid solution, saturate and impregnate the primary zinc oxide precursor for 30min~70min, and dry it at 115~135℃ for 3~4h to obtain primary zinc oxide for deep fine desulfurization at room temperature in CO-rich gas. The secondary zinc oxide is prepared from ZnO, basic zinc carbonate, nano-lime, and volcanic rock; the preparation method of secondary zinc oxide includes the following steps: (1) Mix ZnO powder, basic zinc carbonate, nano lime and crushed volcanic rock in a mass ratio of (2.0~3.2):(1.8~3.0):(2.9~3.7):(1.3~2.1), grind them evenly, add an appropriate amount of deionized water, stir and press evenly, extrude and shape, and keep moist for 12h~24h. (2) After moisturizing, dry at 115℃~135℃ for 3h~4h, cool and load into the tower, purge with nitrogen gas at 300~1000h-1 for 10h~20h, unload and seal in a bag to obtain secondary zinc oxide for deep fine desulfurization at room temperature in CO-rich gas.

2. The zinc oxide used in a CO-rich, ambient-temperature deep desulfurization process according to claim 1, characterized in that: The volume ratio of deoxidizer, primary zinc oxide, hydrolysant, and secondary zinc oxide is (0.5~2.0):(3.0~4.5):(1.2~2.5):(2.5~3.8).