Application of carbon nitride loaded noble metal material

Abstract

The invention relates to the field of air pollution control, in particular to application of a carbon nitride loaded noble metal material in catalytic oxidation of volatile organic compounds (VOCs) in a sulfur-containing atmosphere. The invention provides a method for catalytic oxidation of VOCs in a sulfur-containing atmosphere. The method comprises the following step: carrying out catalytic oxidation on VOCs into carbon dioxide and water in the sulfur-containing atmosphere by adopting the carbon nitride loaded noble metal material. The carbon nitride is responsible for precious metal materials and has good sulfur resistance, and VOCs gas in the sulfur-containing atmosphere can be completely removed at the temperature of 400 DEG C.

Description

Technical Field

[0001] The present invention relates to an application of a carbon nitride-loaded noble metal material, and in particular to an application of a carbon nitride-loaded noble metal material in the catalytic oxidation removal of volatile organic compounds (VOCs), and belongs to the field of air pollution control. Background Art

[0002] Volatile organic compounds (VOCs) are difficult to control due to their wide range of sources and variety, and have a huge impact on human health. Outdoor VOCs are mainly produced by fuel combustion and transportation, and are mainly found in industries such as coal chemical industry and natural gas chemical industry. It is worth noting that low-carbon alkanes, such as ethane, produced in the process flow are symmetrical and stable, and their catalytic conversion is a research focus that cannot be ignored in the industry.

[0003] At present, China has formed a variety of VOCs treatment methods for exhaust gas emissions. The mainstream application technologies include absorption, adsorption, biodegradation, catalytic oxidation, etc. Among them, catalytic oxidation technology has attracted much attention due to its advantages such as no secondary pollution, low energy consumption, and good effect. It is suitable for treating large air volume and low concentration VOCs exhaust gas. At the same time, catalytic oxidation to remove VOCs technology is also one of the recommended technologies of my country's Ministry of Ecology and Environment. However, in the production process of the chemical industry, in addition to the emission of a large amount of VOCs, there will also be a large amount of sulfur-containing gas emissions, such as hydrogen sulfide (H2S), sulfur dioxide (SO2), carbonyl sulfide (COS), etc. These gases greatly affect the activity of VOCs catalysts. Usually, when the volume fraction of sulfides exceeds 5ppm, the catalyst activity is inhibited. Therefore, it is necessary to develop a highly efficient sulfur-resistant catalyst.

[0004] Graphitic carbon nitride (g-C3N4) is a typical carbon-based metal-free catalyst, composed of abundant carbon and nitrogen elements, without expensive rare metals, and has the significant advantages of low cost and environmental friendliness. Its potential for sustainable development and utilization has gradually become a research hotspot in the fields of catalysis and environment. The rich structural alkaline sites on its surface can facilitate the adsorption of sulfur-containing gases, thereby achieving the material's anti-sulfur properties. Combined with the anti-sulfur advantages of carbon nitride materials, by further loading precious metals on its surface, efficient and sulfur-resistant VOCs catalytic materials can be prepared. Summary of the invention

[0005] In order to overcome the shortcomings of the prior art, the present invention provides an application of a carbon nitride-supported noble metal material in the catalytic oxidation of VOCs in a sulfur-containing atmosphere. The carbon nitride-supported noble metal material catalyst prepared by the present invention can efficiently realize the catalytic oxidation of ethane gas in a sulfur-containing atmosphere at a temperature of 400° C., and has good selectivity and life. The present invention has a simple process, high efficiency, and great application prospects.

[0006] The carbon nitride-loaded noble metal material provided by the present invention is used for the efficient removal of VOCs gas in a sulfur-containing atmosphere.

[0007] In the above application, the carbon nitride-loaded precious metal material catalyst achieves 100% catalytic oxidation of VOCs gas in a sulfur-containing atmosphere at a temperature of 400°C.

[0008] The sulfur-containing gas comes from VOCs gas generated in at least one of the fields of petrochemical industry, coal chemical industry and natural gas chemical industry.

[0009] In the above application, the carbon nitride material can be one of graphite phase carbon nitride (g-C3N4), polyheptazine imide (PHI), and polytriazine imide (PTI), and the synthesis precursor can be any one of melamine, dicyandiamide, thiourea, and urea.

[0010] In the above application, the noble metal may be one or more of platinum, palladium, rhodium, and cobalt, and the noble metal precursor may be one or more of chlorides and nitrates of Pt, Pd, Ph, and Co. The loading amount is 0.1-1.0 wt%.

[0011] In the above application, the reaction conditions of the carbon nitride-loaded precious metal material in the catalytic oxidation of VOCs are as follows: the temperature is 20~400°C, specifically 20, 200, 250, 300, 350, 400°C, and the reaction pressure is normal pressure.

[0012] The present invention further provides a method for catalytic oxidation of VOCs in a sulfur-containing atmosphere, comprising the following steps: using the carbon nitride-loaded noble metal material to catalytically oxidize VOCs in a sulfur-containing atmosphere to convert the VOCs into carbon dioxide and water.

[0013] In the above method, the sulfur-containing gas can be at least one of hydrogen sulfide (H2S), sulfur dioxide (SO2), and carbonyl sulfide (COS), and the concentration can be 0~200ppm; the concentration of VOCs gas can be 0~2000ppm; the volume percentage concentration of oxygen is 10%.

[0014] In the above method, the conditions of the catalytic oxidation reaction are as follows: The temperature may be 20-400° C., specifically 20, 200, 250, 300, 350, 400° C., and the reaction pressure is normal pressure.

[0015] In the above method, when the carbon nitride-supported noble metal material catalytically oxidizes the VOCs gas in the sulfur-containing atmosphere on the catalytic reaction bed, the space velocity of the gas can be 1000 h -1 ~150000 h -1 , specifically 30000 h -1 .

[0016] In the present invention, the normal pressure is common knowledge in the art, and refers to one atmospheric pressure, that is, the gas pressure produced by the atmosphere in which we live in daily life. One standard atmospheric pressure is 101325 Pa.

[0017] The significant advantages of the present invention are: Carbon nitride-loaded precious metal material catalysts can efficiently oxidize VOCs gases into carbon dioxide and water, and the catalysts maintain high activity in sulfur-containing atmospheres (H2S, SO2 or COS). BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a graph showing the oxidation activity of the carbon nitride-supported noble metal material catalyst in Example 1 to ethane in different sulfur-containing atmospheres; Figure 2 This is the thermal stability of the carbon nitride-supported precious metal material catalyst in Example 2 to ethane gas in a sulfur dioxide atmosphere. Specific implementation methods

[0019] The present invention is described below by means of specific embodiments, but the present invention is not limited thereto.

[0020] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the reagents used in the following examples, unless otherwise specified, can be obtained from commercial channels.

[0021] The present invention provides an application of a carbon nitride-loaded noble metal material for catalytic oxidation of VOCs in a sulfur-containing atmosphere, comprising the following steps: VOCs, sulfur-containing gas, air and nitrogen are mixed, introduced into a catalytic reactor, and reacted under heating, combustion and the action of a catalyst, thereby catalytically oxidizing the VOCs gas into carbon dioxide and water in the sulfur-containing atmosphere.

[0022] The reaction temperature is 20-400°C, specifically 20, 200, 250, 300, 350, 400°C; The sulfur-containing gas is at least one of H2S, SO2, and COS; Example

[0023] Synthesis method of carbon nitride loaded precious metal materials: The carbon nitride material is obtained by calcining a nitrogen-rich precursor at 450-550° C. for 2-6 hours. The precursor can be any one of melamine, dicyandiamide, thiourea and urea. A certain amount of 2 mmol / L noble metal precursor solution is added to the PVA aqueous solution in an ice water bath and protected from light. The noble metal precursor can be one or more of the chlorides and nitrates of Pt, Pd, Ph, and Co (the mass ratio of noble metal: PVA = 1: 1.2 mg / mg). The solution is stirred magnetically for 30 min until foam is generated. Sodium borohydride solution (2.0 g / L; the molar ratio of noble metal: NaBH4 = 1: 5 mol / mol) is continued to be added and stirred for 30 min. The fired carbon nitride material is placed in the obtained solution and stirred for 7-8 h, then filtered, washed with deionized water and ethanol 2-3 times, and dried at 80°C. The obtained solid is calcined in a muffle furnace, heated to 600°C at a rate of 1°C / min, and kept at 600°C for 2 h to obtain a carbon nitride-loaded noble metal material.

[0024] 0.2 ml of the prepared carbon nitride loaded noble metal catalyst is filled in the quartz reaction tube of the catalytic reactor, and then the mixed gas of sulfur-containing gas and VOCs (taking ethane as an example) is introduced into the catalyst bed for gas-solid phase catalytic reaction to achieve catalytic oxidation of ethane. A temperature measuring thermocouple is inserted in the center of the catalyst bed, and quartz wool is filled at both ends of the catalyst bed to fix it.

[0025] The mass of the catalyst is 0.5 g, and the particle size is 40-60 mesh. A certain amount of ethane gas, sulfur-containing gas (at least one of H2S, SO2, COS), air gas, and nitrogen gas (balance gas) are passed into the catalyst bed for reaction using a volume flow meter. The ethane concentration is 2000 ppm, the sulfur-containing gas concentration is 200 ppm, the oxygen volume percentage concentration is 10%, and the remaining atmosphere is nitrogen. The reaction space velocity is 30000 h -1 As the heating furnace heats up, the catalyst bed temperature rises from 20°C to 400°C, and the reaction pressure is normal pressure.

[0026] The results are as follows Figure 1 Shown is the activity diagram of the catalytic oxidation of ethane in a sulfur-containing atmosphere by carbon nitride-supported precious metal materials.

[0027] Depend on Figure 1It can be seen that: during the heating process of the reactor, the ethane conversion rate increases with the increase of temperature. When ethane gas is introduced alone, the conversion rate reaches 90% at 269°C and 100% at 350°C. After the introduction of sulfur-containing gas, the catalytic activity of ethane is reduced, but the conversion rate can still reach 100% at 400°C, showing good activity and stability. It is worth noting that as the temperature increases, carbonyl sulfide in the reaction gas is gradually converted into sulfur dioxide, so the ethane conversion curves of the two are similar. Example

[0028] (1) Filling the quartz reaction tube of the catalytic reactor with 0.2 ml of carbon nitride-supported noble metal catalyst; (2) Use a volume flow meter to control a certain amount of ethane gas, sulfur-containing gas (at least one of H2S, SO2, COS), air gas, and nitrogen gas (balance gas) to enter the catalyst bed for reaction. The ethane concentration is 2000 ppm, the oxygen volume percentage concentration is 10%, and the remaining atmosphere is nitrogen. The reaction space velocity is 30,000 h -1 As the temperature of the heating furnace was raised, the catalyst bed temperature was raised from 20°C to 400°C, 200 ppm sulfur-containing gas was introduced at 400°C and maintained for 17 hours, and the introduction of sulfur-containing gas was stopped and maintained for 13 hours. The reaction pressure was normal pressure.

[0029] Depend on Figure 2 It can be seen that after the introduction of sulfur-containing gas, the ethane conversion rate gradually decreased with the increase of the introduction time of sulfur-containing gas. After 17 hours of introduction, the ethane conversion rate decreased from 100% to 75.6%; after stopping the introduction of sulfur-containing gas, the catalyst activity recovered, and the ethane conversion rate reached 90% at the 20th hour, and recovered to the original activity at the 30th hour. This shows that the synthesized carbon nitride-supported noble metal catalyst has good thermal stability.

Claims

1. Application of a carbon nitride-loaded precious metal material for efficient catalytic oxidation of VOCs in a sulfur-containing atmosphere.

2. The use according to claim 1, characterized in that: The carbon nitride material can be one of graphite carbon nitride (g-C3N4), polyheptazine imide (PHI), and polytriazine imide (PTI), and the synthesis precursor can be any one of melamine, dicyandiamide, thiourea, and urea.

3. The use according to claim 1, characterized in that: The noble metal may be one or more of platinum, palladium, rhodium, and cobalt, and the noble metal precursor may be one or more of chlorides and nitrates of Pt, Pd, Ph, and Co. The loading amount is 0.1-1.0 wt%.

4. The use according to claims 1-3, characterized in that: The reaction conditions of the carbon nitride-supported noble metal material in catalytic oxidation of ethane in a sulfur-containing atmosphere are as follows: the temperature is 20-400° C. and the reaction pressure is normal pressure.

5. The use according to claim 4, characterized in that: The sulfur-containing gas comes from VOCs gas generated in at least one of the fields of petrochemical industry, coal chemical industry and natural gas chemical industry.

6. The method according to claim 4 or 5, characterized in that: The VOCs concentration is 0-2000ppm, the oxygen volume percentage concentration is 10%. The sulfur-containing gas is at least one of hydrogen sulfide, carbonyl sulfide, and carbon disulfide, and the concentration is 0-200ppm.

7. The use according to claim 4-6, comprising the following steps: when the carbon nitride-supported noble metal material catalytically oxidizes the ethane gas in the sulfur-containing atmosphere on the catalytic reaction bed, the space velocity of the gas can be 1000 h -1 ~150000 h -1 .

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