A method for preparing semiconductor VOCs waste gas adsorbent

Abstract

The present invention discloses a method for preparing a semiconductor VOCs waste gas adsorbent, which comprises: step 1, selecting a molecular sieve as an adsorbent carrier; step 2, preparing a sulfuric acid solution of a certain concentration; step 3, adding an appropriate amount of molecular sieve to the prepared sulfuric acid solution and continuously stirring it to make it fully treated with sulfuric acid, then filtering and separating the solid part to dry it, and grinding it into powder after drying for standby use; step 4, fully mixing the powder with silica sol, hydroxypropyl methylcellulose, and field sesbania powder in a certain mass ratio to obtain a mixed powder, and then kneading to obtain a mixture, and then making the mixture into a sample with a shape; step 5, naturally drying the obtained sample and calcining it at high temperature in a muffle furnace, and at the same time continuously passing water vapor into the muffle furnace to obtain an adsorbent product. The adsorbent product prepared by the present invention has good performance in removing VOCs waste gas, and the effect is maintained for a long time. It also has a good adsorption effect under high humidity conditions, and can achieve the purpose of recycling.

Description

Technical Field

[0001] The invention relates to a method for preparing a semiconductor VOCs waste gas adsorbent, and belongs to the field of air purification materials. Background Art

[0002] There are three types of waste gas released during the production process of the semiconductor industry: acidic waste gas, alkaline waste gas and organic waste gas. We focus on organic waste gas (VOCs). Organic waste gas mainly comes from processes such as photolithography, development, etching and diffusion. In these processes, organic solvents (such as isopropyl alcohol) are used to clean the surface of the chip, and the waste gas generated by its volatilization is one of the sources of organic waste gas; at the same time, the photoresist (photoresist) used in the process of photolithography and etching contains volatile organic solvents, such as butyl acetate, which also evaporate into the atmosphere during the chip processing process, which is another source of organic waste gas. The main methods for treating organic waste gas are:

[0003] (1) Combustion method: It is divided into direct combustion method and indirect combustion method. Direct combustion requires the following conditions: VOCs are fully integrated in the high-temperature combustion air instantly; the necessary combustion temperature is guaranteed; and the residence time required for the complete combustion of VOCs is guaranteed. The direct combustion method is suitable for treating VOCs gas with not too large air volume, high temperature and high concentration. Its disadvantage is that it consumes a lot of energy. The disadvantage of the indirect combustion method is that it can only treat low-concentration VOCs gas, and the catalyst is easily poisoned and aged.

[0004] (2) Condensation method: Since substances have different saturated vapor pressures at different temperatures, by lowering the temperature or increasing the pressure, the partial pressure of the organic components in the waste gas is equal to the saturated vapor pressure at that temperature, and the organic components are condensed into liquid and separated from the gas phase. It is generally used to treat high-concentration organic waste gas and VOCs containing a large amount of water vapor.

[0005] (3) Activated carbon adsorption method: Activated carbon adsorption method is an earlier developed method for removing VOCs. It is mainly applicable to gases with low VOCs concentration. However, this method requires special maintenance and has high operating costs.

[0006] In summary, the current problems in treating semiconductor VOCs waste gas are:

[0007] (1) Using the above method to treat semiconductor VOCs waste gas requires too much time and economic cost, and the daily maintenance workload is too large;

[0008] (2) When the above method is used to treat semiconductor VOCs waste gas, secondary pollution will occur and the waste gas problem cannot be fundamentally solved.

[0009] (3) When using the above method to treat semiconductor VOCs waste gas, there are problems with recycling and the adsorbent is difficult to regenerate.

[0010] (4) The above method is less effective in treating semiconductor VOCs waste gas under high humidity conditions. Summary of the invention

[0011] The purpose of the present invention is to provide a method for preparing a semiconductor VOCs waste gas adsorbent. The adsorbent prepared by this method has better performance and effect in semiconductor VOCs waste gas treatment.

[0012] The technical solution adopted by the present invention is as follows:

[0013] A method for preparing a semiconductor VOCs waste gas adsorbent comprises the following steps:

[0014] Step 1: Select molecular sieve as adsorbent carrier;

[0015] Step 2: prepare sulfuric acid solution: under normal temperature and pressure, slowly add a certain amount of concentrated sulfuric acid into an appropriate amount of water and stir to dissolve to obtain a sulfuric acid solution of a certain concentration;

[0016] Step 3: Molecular sieve acid treatment: add an appropriate amount of molecular sieve to the sulfuric acid solution prepared in step 2 and continue stirring to make it fully treated with sulfuric acid, then separate the treated solid-liquid mixture by suction filtration, dry the solid part, and grind it into powder after drying for use;

[0017] Step 4, molecular sieve molding: the powder in step 3 is fully mixed with silica sol, hydroxypropyl methylcellulose and sesbania powder in a certain mass ratio to obtain a mixed powder, and then the mixed powder is added into a kneading machine for kneading to obtain a kneaded mixture, and then the mixture is made into a sample with a shape;

[0018] Step 5. Steam calcination and drying: The obtained sample is naturally dried under normal temperature and humidity conditions, and then calcined at high temperature in a muffle furnace. At the same time, water vapor is continuously introduced into the muffle furnace to obtain an adsorbent product with high mechanical strength and semiconductor VOCs waste gas purification effect.

[0019] Furthermore, the adsorbent carrier is selected from β molecular sieve or ZSM-5 molecular sieve.

[0020] Furthermore, the molecular formula of the beta molecular sieve is |Na7|[Al7Si 57 O 128 ], the silicon-aluminum ratio is 200-250; the molecular formula of the ZSM-5 molecular sieve is 0.9±0.2M 2 / n O:Al2O3:5-100SiO2:zH2O, silicon-aluminum ratio is 300-400.

[0021] Furthermore, the concentration of the sulfuric acid solution configured in step 2 is 1-1.25 mol / L.

[0022] Furthermore, in the step three, a proper amount of molecular sieves is added to the sulfuric acid solution and stirred continuously for 12-24 hours; after separation by suction filtration, the solid part is placed in a 120° C. oven and dried for 12 hours, and after drying, is ground into powder using an agate mortar.

[0023] Furthermore, in the step 4, the powder is fully mixed with silica sol, hydroxypropyl methylcellulose and field sesbania powder in a mass ratio of 100:30-35:1-2:2-4 to obtain a mixed powder; the mixed powder is then added to a kneader and kneaded for 2-4 hours to obtain a kneaded mixture, and then the mixture is formed into a strip sample by a screw extruder or into a spherical sample by a spherical machine.

[0024] Furthermore, in the step five, the sample is calcined in a muffle furnace at a temperature of 500-600° C., a programmed heating rate of 8-10° C. / min, and a calcination time of 4-5 h.

[0025] The adsorbent prepared by the above preparation method can be used in the removal of semiconductor VOCs waste gas.

[0026] The beneficial effects of the present invention are:

[0027] (1) This method successfully prepares a molecular sieve adsorbent product with a high silicon-aluminum ratio by treating the molecular sieve porous material with sulfuric acid. This adsorbent product has good performance in removing VOCs waste gas and the effect is maintained for a long time.

[0028] (2) The VOCs adsorbent prepared by this method is treated by steam roasting. The product prepared after the treatment has a high hydrophobicity and has a good adsorption effect under conditions of high humidity.

[0029] (3) The VOCs adsorbent prepared by this method can be recycled and regenerated, and the adsorption performance of the adsorbent itself will not be affected after regeneration, so the purpose of recycling can be achieved.

[0030] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. DETAILED DESCRIPTION

[0031] The present invention is described in detail below with reference to specific embodiments.

[0032] A method for preparing a semiconductor VOCs waste gas adsorbent comprises the following steps:

[0033] (1) Material preparation: β molecular sieve (molecular formula: |Na7|[Al7Si57O128], silicon-aluminum ratio: 200-250) or ZSM-5 molecular sieve (molecular formula: 0.9±0.2M2 / nO:Al2O3:5-100SiO2:zH2O, silicon-aluminum ratio: 300-400) powder is selected as the adsorbent carrier.

[0034] (2) Preparation of sulfuric acid solution: Under normal temperature and pressure, slowly add a certain amount of concentrated sulfuric acid into an appropriate amount of water and stir to dissolve for 0.5-1h, and make the concentration of the sulfuric acid solution be 1-1.25 mol / L.

[0035] (3) Molecular sieve acid treatment: Add an appropriate amount of β molecular sieve or ZSM-5 molecular sieve to the sulfuric acid solution prepared in step (2) and continue stirring for 12-24 hours to allow it to be fully treated with sulfuric acid. The treated solid-liquid mixture is separated by suction filtration, and the solid part is placed in a 120°C oven and dried for 12 hours. After drying, it is ground into powder using an agate mortar for later use.

[0036] (4) Molecular sieve molding: The powder in step (3) is fully mixed with silica sol, hydroxypropyl methylcellulose, and sesbania powder in a mass ratio of 100:30-35:1-2:2-4 to obtain a mixed powder. The mixed powder is added to a kneader and kneaded for 2-4 hours to obtain a kneaded mixture. The mixture is formed into strip or spherical samples by a screw extruder or a pelletizer.

[0037] (5) Steam calcination and drying: The obtained sample is naturally dried for 24h-48h under normal temperature and humidity conditions, and then calcined in a muffle furnace at high temperature. At the same time, water vapor is continuously introduced into the muffle furnace. The calcination temperature is maintained at 500-600°C, the program heating rate is 8-10°C / min, and the calcination time is 4-5h. At this time, a strip or spherical adsorbent product with high mechanical strength and semiconductor VOCs waste gas purification effect is obtained.

[0038] Specific Example 1: β molecular sieve powder was selected as the main adsorbent, the sulfuric acid solution was configured to be 1 mol / L, the mass ratio of the mixture powder used for molding to silica sol, hydroxypropyl methylcellulose, and sesbania powder was 100 parts, 30 parts, 1.5 parts, and 2 parts, respectively, and the kneading time was 2 hours. The roasting temperature was 500°C and the roasting time was 4 hours.

[0039] Specific Example 2: β molecular sieve powder was selected as the main adsorbent, the sulfuric acid solution was configured to be 1.25 mol / L, the mass ratio of the mixture powder used for molding to silica sol, hydroxypropyl methylcellulose, and sesbania powder was 100 parts, 35 parts, 2 parts, and 4 parts, respectively, and the kneading time was 4 hours. The roasting temperature was 500°C and the roasting time was 4 hours.

[0040] Specific Example 3: ZSM-5 molecular sieve powder was selected as the main adsorbent, the sulfuric acid solution was configured to be 1 mol / L, the mass ratio of the mixture powder used for molding to silica sol, hydroxypropyl methylcellulose, and sesbania powder was 100 parts, 30 parts, 1.5 parts, and 2 parts, respectively, and the kneading time was 2 hours. The roasting temperature was 600°C and the roasting time was 5 hours.

[0041] Specific Example 4: ZSM-5 molecular sieve powder was selected as the main adsorbent, the sulfuric acid solution was configured to be 1 mol / L, the mass ratio of the mixture powder used for molding to silica sol, hydroxypropyl methylcellulose, and sesbania powder was 100 parts, 35 parts, 2 parts, and 4 parts, respectively, and the kneading time was 4 hours. The roasting temperature was 600°C and the roasting time was 5 hours.

[0042] The raw materials used in this method can be obtained through common commercial channels.

[0043] With reference to ISO10121-1-2014 "Test methods for performance evaluation of gas-phase air purification media and devices for general ventilation Part 1: Gas-phase air purification media", the adsorbent prepared by this method was tested and evaluated for its adsorption and removal effect on semiconductor VOCs using a VOCs adsorption and desorption test bench. The VOCs gas used in the test is isopropanol, which accounts for a relatively high proportion of semiconductor waste gas. The test conditions are as follows: the test temperature is 25°C, the humidity is 50% RH, the concentration of isopropanol generated by the equipment is 20ppm, 50g of this adsorbent is filled in the reactor, and the treatment is carried out for a total of 12h. The outlet isopropanol concentration is tested at 2, 4, 6, 8, 10, and 12h, respectively, and compared with the adsorption effect of traditional activated carbon. The results are shown in the following table:

[0044]

[0045] From the data in the above table, it can be seen that the adsorbent prepared by this method has a good removal effect on semiconductor VOCs and maintains it for a long time. It can reduce the concentration of isopropanol from 10ppm to below 1ppm within 12 hours, meeting the actual use needs of removing VOCs and the removal effect is significantly better than traditional activated carbon. At the same time, the type of molecular sieve used in the formula, the type of binder, the formula ratio, the kneading time, the roasting conditions, etc. also have a significant impact on the deodorization effect of the adsorbent.

[0046] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the protection scope of the present invention in any form, and all technical solutions obtained by equivalent replacement and the like fall within the protection scope of the present invention.

[0047] The parts not involved in the present invention are the same as the prior art or can be implemented by using the prior art.

Claims

1. A method for preparing a semiconductor VOCs waste gas adsorbent, characterized in that The following steps are involved: Step 1: Select molecular sieve as adsorbent carrier; the adsorbent carrier is β molecular sieve or ZSM-5 molecular sieve; the molecular formula of β molecular sieve is |Na7|[Al7Si 57 O 128 ], the silicon-aluminum ratio is 200-250; the silicon-aluminum ratio of ZSM-5 type molecular sieve is 300-400; Step 2: prepare sulfuric acid solution: under normal temperature and pressure, slowly add a certain amount of concentrated sulfuric acid into an appropriate amount of water and stir to dissolve to obtain a sulfuric acid solution of a certain concentration; Step 3: Molecular sieve acid treatment: add an appropriate amount of molecular sieve to the sulfuric acid solution prepared in step 2 and continue stirring to make it fully treated with sulfuric acid, then separate the treated solid-liquid mixture by suction filtration, dry the solid part, and grind it into powder after drying for use; Step 4, molecular sieve molding: the powder in step 3 is fully mixed with silica sol, hydroxypropyl methylcellulose and sesbania powder in a certain mass ratio to obtain a mixed powder, and then the mixed powder is added into a kneading machine for kneading to obtain a kneaded mixture, and then the mixture is made into a sample with a shape; Step 5. Steam calcination and drying: The obtained sample is naturally dried under normal temperature and humidity conditions, and then calcined at high temperature in a muffle furnace. At the same time, water vapor is continuously introduced into the muffle furnace to obtain an adsorbent product with high mechanical strength and semiconductor VOCs waste gas purification effect.

2. The method for preparing a semiconductor VOCs waste gas adsorbent according to claim 1, characterized in that: The concentration of the sulfuric acid solution prepared in step 2 is 1-1.25 mol / L.

3. The method for preparing a semiconductor VOCs waste gas adsorbent according to claim 1, characterized in that: In the step 3, a proper amount of molecular sieves is added to the sulfuric acid solution and stirred continuously for 12-24 hours; after separation by suction filtration, the solid part is placed in a 120° C. oven for drying for 12 hours, and after drying, it is ground into powder using an agate mortar.

4. The method for preparing a semiconductor VOCs waste gas adsorbent according to claim 1, characterized in that: In the step 4, the powder is fully mixed with silica sol, hydroxypropyl methylcellulose and sesbania powder in a mass ratio of 100:30-35:1-2:2-4 to obtain a mixed powder; the mixed powder is then added to a kneader and kneaded for 2-4 hours to obtain a kneaded mixture, and then the mixture is formed into a strip sample by a screw extruder or into a spherical sample by a spheroidizer.

5. The method for preparing a semiconductor VOCs waste gas adsorbent according to claim 1, characterized in that: In the step 5, the sample is calcined in a muffle furnace at a temperature of 500-600° C., a program heating rate of 8-10° C. / min, and a calcination time of 4-5 h.

6. Use of the adsorbent prepared by the preparation method according to any one of claims 1 to 5 in the removal of semiconductor VOCs waste gas.

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