TWI417133B - Methof for dealing with dichloromethane by using a mesoporous catalyst - Google Patents

Description

Medium hole catalyst for treating dichloromethane

The present invention relates to a method for preparing a mesoporous catalyst comprising an active center comprising Fe, Ti, Pt metal or other oxides, and a method for treating a chlorine-containing volatile organic compound.

Volatile Organic Compounds (VOCs) are common air pollutants emitted by the chemical and petrochemical industries. Among them, Chlorinated Volatile Organic Compounds (CVOCs) are one of the main types, and CVOCs have good thermal stability. There is a significant conversion reaction when the treatment temperature is above 823K. For example, methylene chloride must be thermally cracked at a temperature of 823K, and the conversion rate is only 25%.

Currently, volatile organic compounds (VOCs) are mainly treated by catalyst incineration. The catalyst is a new mesoporous material synthesized from a citrate-coated quaternary ammonium salt surfactant. MCM-41 (Mobil Composition of Matter) No.41), which has high surface area (1000m ² /g), high thermal stability, adjustable pore size, etc., and is widely used in the adsorption and recovery of catalyst carriers and contaminants; and in the MCM-41 pore structure The transitional or non-transition metal can produce an active site with acidic and redox properties in the structure, which greatly improves the oxidation and reduction ability, thereby improving the catalytic performance of MCM-41.

However, due to the high cost and high temperature cracking and oxidation reaction of MCM-41, it is only suitable for low temperature adsorption and recovery. The application of MCM-41 in the treatment of CVOCs by catalytic incineration is not much research. Therefore, if the characteristics of catalysts are improved, the dispersibility of metal precursor ions in the pores can be increased, and MCM can be improved during the reaction. The adsorption capacity of -41 on gas molecules promotes the catalytic efficiency of the catalyst, which will reduce the energy required for the incineration of CVOCs by the catalyst and enhance the application value of MCM-41.

The catalyst provided by the present invention prepares a carrier having a mesopores by a sol-gel method, and adds Fe, Ti, a Pt metal or an oxide thereof to modify the surface of the carrier to form a catalyst.

The invention also provides a method for treating methylene chloride with the aforementioned catalyst, the method comprising the steps of: (a) providing a gas containing dichloromethane (CH2Cl2); (b) providing an appropriate amount by a sol-gel method and selected from Fe- a hole catalyst in MCM-41, Ti-MCM-41 or Pt-MCM-41; (c) causing the mesoporous catalyst to be incinerated by the catalyst incineration method with the methylene chloride-containing gas.

Synthetic cerium oxide pore materials, such as MCM-41, the organic matter is a surfactant, and the inorganic substance is mainly derived from phthalate or organic bismuth (TEOS). Since the citrate concentration is greater than 100 mM, it will self-polymerize in aqueous solution. Its anion will exhibit various complex polymers due to different pH values; among them, tannic acid polymerization with a pH greater than 7, tannic acid monomer (H ₄ SiO ₄ ) and tannic acid dimer (H ₂ Si ₂ O ₇ ) in a highly alkaline environment (pH 10), some will produce dissociation, as for larger tannic acid polymers, such as cyclic tannic acid (H ₆ Si ₃ O ₉ ), bitricyclic decanoic acid (H ₆ Si ₆ O ₁₅ ), etc. Alkaline environment (pH 10) Largeer citrate molecules form polyelectron anion with high negative charge. When these highly acidic citrate anions easily replace the opposite ions on the cationic microcells and bind to the microcells .

The formation mechanism of MCM-41 is mainly composed of a positively charged quaternary ammonium salt surfactant, which has the property of having one end hydrophobic end and one end hydrophilic in water, forming a microcell structure and a negatively charged cerium oxide in a solution in a base. The aqueous solution is mixed and replaced with the negative ion of the original hydrophilic end, and the inorganic citrate is condensed and polymerized with the organic surfactant to form a hexagonal regular pore structure, and the organic template can be removed by calcination. Obtaining MCM-41, the source of the cerium oxide may be a ceric acid salt or an organic cerium compound, for example, tetraethylortho silicate (TEOS), and the quaternary ammonium salt is most commonly used mainly as cetyltrimethyl ( C ₁₆ TMAB).

Surface modification refers to the chemical or physical property of chemically and physically changing the bond to be modified on the surface of a medium pore material. Organic decane refers to the property of covalently bonding a silane to a surface of a ruthenium oxide wall via a chemical reaction to facilitate separation or catalytic reaction. The surface modification of decane is the use of a ruthenium hydroxyl group (Si-OH) on the surface of the molecular sieve, in which the H atom combines with the active end of decane and is removed, and produces a covalent bond with the surface to form an inorganic-organic (inorganic-organic) surface modification reaction.

The invention prepares a medium-hole catalyst by a sol-gel method, and the synthesis method comprises the steps of: mixing and mixing the alkyl-based organic template and the cerium oxide in a synthesis ratio, and placing it at a characteristic temperature for several hours to form The crystal structure was placed, and the mixed precursor colloid was placed for 24 hours. Finally, the resulting precipitate was filtered with deionized water, washed to a pH of about 7, and dried at 120 ° C until overnight, and calcined at 540 ° C for 6 hours. The medium hole carrier can be obtained.

The invention adopts a quaternary ammonium salt interfacial activity and a mixture of bismuth citrate or organotelluride (TEOS), respectively reacted with a metal salt solution containing iron, titanium and platinum, and continuously stirred at room temperature for 2 hours, and placed overnight. The initial product is washed with deionized water and filtered to a pH of about 7. It is placed in an oven and dried at 120 ° C until overnight to obtain a hole in the initial preparation of gold or its oxide catalyst, which is then dried. The solid product was placed in a high temperature furnace and calcined at 540 ° C for 6 hours to form a metal or its oxide catalyst on the surface of the mesoporous support to form an active center.

The above-mentioned obtained medium-cavity catalyst can be used for the treatment of volatile organic compounds by catalytic incineration. Catalytic oxidation uses a catalyst composed of metal and metal oxide as a catalyst to enable the incineration reaction to be carried out at a lower temperature. The temperature range of the catalyst-reactive volatile organic compounds is about 298~400K, which can completely destroy the volatile organic compounds into carbon dioxide and water. The spatial velocity of the system designed to handle volatile organic compounds is controlled at 1800-9000 hr ^-1 . The spatial flow velocity definition refers to the volume of reactants passing through a unit volume of the catalyst bed per unit time. The concentration of volatile organic compounds ranges from 100 to 250 ppm.

The main equipment of the experimental device of the invention is divided into the following three parts:

The VOC gas system uses air pump gas to raise the volatile organic compounds in the bottle and formulate the concentration of volatile organic compounds. Use a float flow meter to regulate the flow of gas and stripping. The gas mixing tank is uniformly mixed with the concentration of volatile organic compounds in the impingement bottle into the mixing tank through the air pump, and then the required gas concentration is set, and then introduced into the tubular high temperature furnace for catalytic reaction.

The catalyst heating furnace heating system is composed of a tubular high temperature furnace and a volatile organic catalyst reaction tube. The tubular high temperature furnace has a double layer structure, air cooling convection design, and accelerates the temperature rise and fall. The maximum set temperature is 1200 ° C. Multi-stage heater to control, length 30~50cm, inner diameter: 6~8cm; outer diameter: 23~25cm, high temperature protection device (including thermal insulation material). The volatile organic catalyst reaction tube was made of quartz and had a length of 70 cm, an inner diameter of 2 cm, and an outer diameter of 2.4 cm. Horizontally placed in a high-temperature tubular furnace, a glass filter plate is embedded with a quartz filter plate, which is used for containing a catalyst for catalytic reaction, and the filter plate is sufficient for gas molecules to pass, and the gas after the reaction is gas chromatography. The instrument (GC-FID) detects changes in concentration before and after the reaction.

The gas sampling and analysis system uses a gas chromatograph (GC-FID) to analyze the concentration of organic gases. Before the catalytic reaction, it is necessary to adjust the concentration of organic gases. A gas chromatograph was used to analyze the change in gas concentration after the catalytic reaction.

The invention adopts self-prepared catalyst to carry out catalytic reaction of dichloromethane, adopts continuous flow reactor as performance test method, analyzes the outlet concentration by gas chromatography (GC-FID), evaluates conversion efficiency, and evaluates it. Operational feasibility, as shown in Figure 1, the experimental steps are as follows: (a) dichloromethane supply step 1: provide gas containing dichloromethane (CH ₂ Cl ₂ ); (b) medium pore catalyst supply step 2 : providing an appropriate amount of pore catalyst prepared by a sol-gel method and selected from Fe-MCM-41, Ti-MCM-41 or Pt-MCM-41; (c) treating the dichloromethane by catalytic incineration step 3: The mesoporous catalyst is incinerated by the catalyst incineration method with the methylene chloride-containing gas.

The various features of the invention are illustrated by the following examples. The GC was chromatographed using a chromatography column model 80/100 mesh Porapak Q chromatography. The GC-FID analysis conditions were as follows: nitrogen: 14 psi, hydrogen: 20 psi, air: 5 psi, column temperature: 200 ° C, FID (Detector) temperature: 250 ° C, injection nozzle (Injector) temperature: 125 ° C. XRPD analysis uses CuKα as the radiation source (λ=0.1541nm), the instrument output power is 18KW, 1.5°~10° under the condition; the scanning between 20°~80°, the scanning speed is 0.5°/min. B.E.T. Analysis The sample was subjected to vacuum removal at 350 ° C for 17 hours, and then placed in the analysis tank of the instrument for adsorption/desorption experiments. The isothermal adsorption/desorption curve of the sample was measured at -196 ° C (77 K) to determine the surface area, pore size and pore volume of the mesoporous product. TEM analysis is to dissolve a small amount of sample in an appropriate amount of absolute alcohol, and then ultrasonically oscillate to form a uniformly dispersed solution, and then take a small amount. The solution is dropped on a copper mesh with a carbon film and allowed to stand for a few minutes. After the sample is dried, it can be directly observed and photographed.

Example 1

Please refer to Figure 8. If the chlorine-containing volatile organic compounds are chemically reacted at the high temperature without catalyst catalysis, it is called homogeneous reaction. Observing the homogeneous reaction, in addition to observing the thermal stability of CVOCS, can also be used as the study. The medium blank test group was used to understand whether the treatment temperature has a conversion effect on methylene chloride, and the true contribution of the catalyst to the incineration reaction can be obtained. The test conditions are that the methanol inlet concentration is controlled between 100 and 250 ppm, and the space flow rate is controlled at 1800 hr ^-1 . It can be seen from the figure that the reaction temperature of dichloromethane is 300 to 823 K, and the conversion rate is not high during the process. The thermal stability is good, but the conversion reaction is more obvious at a treatment temperature of 773 K or more. It is shown by a blank experiment that methylene chloride is further decomposed by a thermal cracking effect at a high temperature, and the conversion rate is about 25%.

Example 2

4.6 g of cetyltrimethylammonium bromide (CTMABr) was dissolved in 95 ml of deionized water, 8.3 ml of aqueous ammonia (NH ₄ OH, 28% by weight) was added, and at room temperature was used as an electromagnetic stirrer 15 Minute to complete dissolution of cetyltrimethylammonium bromide, add 8.8 ml of tetraethoxy decane (TEOS) dropwise to the aqueous solution of cetyltrimethylammonium bromide, and continue stirring at room temperature 2 hour. The stirred sample solution was collected by suction filtration to a white precipitate which was placed in an oven and dried at 120 ° C overnight. The dried product was placed in a high temperature furnace at 540 ° C for 6 hours to obtain a mesoporous catalyst. The catalyst was represented by MCM-41.

The XRPD pattern of the obtained MCM-41 is shown in Fig. 2, which shows the MCM-41 after calcination, and the angle 2θ has diffraction peaks at 2.28°, 3.98° and 4.58°, indicating that the MCM-41 has a hexagonal symmetrical structure. Fig. 4 is a TEM image of the obtained MCM-41, and the arrangement of the mesopores in the MCM-41 after calcination can be observed, and the appearance of some of the particles exhibits a circular or hexagonal shape. The BET specific surface area of MCM-41 obtained by nitrogen absorption was about 1147 m ² /g. The BET specific surface area of MCM-41 obtained from Fig. 3 was an average pore diameter of 3.04 nm and an average pore volume of 1.14 cm ³ /g.

Next, please refer to Figure 9 for the treatment of chlorine-containing volatile organic compounds with the catalyst prepared above, and use the air pump to raise the methylene chloride in the impact bottle and mix it to a concentration of 250 ppm to adjust the gas with a float flow meter. The space flow rate is 1800 hr ^-1 , and it is uniformly mixed into the gas mixing tank, and then introduced into the catalytic reactor heating system, heated from 300K to 823K for catalytic reaction, and the gas after the reaction is gas chromatograph. (GC-FID) analysis of the change in concentration before and after the reaction, as shown in Fig. 9, the conversion of methylene chloride at 823 K was about 40%.

Example 3

2.5 g of cetyltrimethylammonium bromide (CTMABr) was dissolved in 125 ml of deionized water, 10 ml of aqueous ammonia (NH ₄ OH, 28% by weight) was added, and at room temperature was used as an electromagnetic stirrer 15 Minutes to complete dissolution of cetyltrimethylammonium bromide, 5.2 ml of tetraethoxy decane (TEOS) with 10.4 ml of isopropanol (Propanol-2) and 0.9 g of ferric nitrate (Fe(NO ₃ ) ₃ . 9H ₂ O) was uniformly stirred and stirred, and then added dropwise to an aqueous solution of cetyltrimethylammonium bromide, and stirring was continued at room temperature for 2 hours, and then left overnight. The sample solution was collected by suction filtration and rinsed with deionized water to a pH of about 7. It was placed in an oven and dried at 120 ° C until overnight. The dried product was placed in a high temperature furnace at 540 ° C for 6 hours to obtain a metal oxide product of iron in the hole, and the product was represented by Fe-MCM-41.

The XRPD pattern of the obtained Fe-MCM-41 is shown in Fig. 2, which shows that the calcined Fe-MCM-41 has a (100) crystal plane 29 of 2.20° and a d-spacing value of 4.01 nm, as observed from the figure. The intensity of the diffraction front is weak, indicating that the Fe-MCM-41 still has a hexagonal symmetrical structure. Figure 5 is a TEM image of the obtained Fe-MCM-41. It can be seen that when the iron metal (ion) is modified (implanted) into the MCM-41 skeleton, the crystallinity of MCM-41 is deteriorated, and it is difficult to see the hexagonal arrangement. Hole accumulation structure. The BET specific surface area of Fe-MCM-41 obtained by nitrogen absorption was about 988 m ² /g. The average pore diameter obtained from Fig. 3 was 3.68 nm, and the average pore volume was 0.94 cm ³ /g.

Next, please refer to Figure 9 for the treatment of chlorine-containing volatile organic compounds with Fe-MCM-41. The air pump is used to raise the methylene chloride in the impact bottle and mix it at a concentration of 250 ppm to adjust the gas with a float flow meter. space velocity of 1800hr ^-1, the uniformly mixed gas entering the mixing vessel, then pass into the catalytic reactor heating system, heat from 300K to 823K, the catalyst for the catalytic reaction, after the reaction gas by a gas chromatograph ( GC-FID) analysis of the change in concentration before and after the reaction, as shown in Figure 9, the conversion of methylene chloride at 823 K was about 90%.

Example 4

2.5 g of cetyltrimethylammonium bromide (CTMABr) was dissolved in 125 ml of deionized water, 10 ml of aqueous ammonia (NH ₄ OH, 28% by weight) was added, and at room temperature was used as an electromagnetic stirrer 15 Minutes to complete dissolution of cetyltrimethylammonium bromide, 5.2 ml of tetraethoxydecane (TEOS) with 10.4 ml of isopropanol (Propanol-2) and 2 ml of titanium tetrabutoxide (Ti (OC _{4 )} H ₉ ) ₄ ) The mixture was uniformly stirred and added dropwise to an aqueous solution of cetyltrimethylammonium bromide, and stirring was continued at room temperature for 2 hours, and then allowed to stand overnight. The sample solution was collected by suction filtration and rinsed with deionized water to a pH of about 7. It was placed in an oven and dried at 120 ° C until overnight. The dried product was placed in a high temperature furnace at 540 ° C for 6 hours to obtain a titanium-containing mesoporous metal oxide product, which was represented by Ti-MCM-41.

The XRPD pattern of the obtained Ti-MCM-41 is shown in Fig. 2, which shows that the calcined Ti-MCM-41 has a 2θ of 2.30° on the (100) crystal plane and a d-spacing value of 3.84 nm, as observed from the figure. The intensity of the diffraction front is weakened, indicating that the Ti-MCM-41 still has a hexagonal symmetrical structure. Fig. 6 is a TEM image of the obtained Ti-MCM-41. It can be seen that when the iron metal (ion) is modified (implanted) into the MCM-41 skeleton, the crystallinity of the MCM-41 is deteriorated, and the hexagonal arrangement is less likely to be seen. Hole accumulation structure. Measured by nitrogen adsorption resulting Ti-MCM-41 BET specific surface area of from about 772m ² / g. The average pore diameter obtained from Fig. 3 was 4.00 nm, and the average pore volume was 0.79 cm3/g.

Next, please refer to Figure 9 for the treatment of chlorine-containing volatile organic compounds with Ti-MCM-41. The air pump is used to raise the methylene chloride in the impact bottle and mix it at a concentration of 250 ppm to adjust the gas with a float flow meter. The space flow rate is 1800 hr ^-1 , and it is uniformly mixed into the gas mixing tank, and then introduced into the catalytic reactor heating system, heated from 300K to 823K for catalytic reaction, and the gas after the reaction is gas chromatograph ( GC-FID) analysis of the change in concentration before and after the reaction, as shown in Figure 9, the conversion of methylene chloride at 823 K was about 85%.

Example 5

1.2 g of cetyltrimethylammonium bromide (CTMABr) was dissolved in 60 ml of deionized water, 18.8 ml of aqueous ammonia (NH ₄ OH, 28% by weight) was added, and at room temperature was used as an electromagnetic stirrer 15 Minute to cetyltrimethylammonium bromide completely dissolved, 0.1 g of potassium hexachloroplatinate (K ₂ PtCl ₆ ) dissolved in 2.5 ml of deionized water and 5.3 ml of tetraethoxy decane (TEOS), and then The aqueous solution of cetyltrimethylammonium bromide was added dropwise, and the mixture was stirred at room temperature for 2 hours, and allowed to stand overnight. The sample solution was collected by suction filtration and rinsed with deionized water to a pH of about 7. It was placed in an oven and dried at 120 ° C until overnight. The dried product was placed in a high temperature furnace at 540 ° C for 6 hours to obtain a pore-containing metal oxide product in platinum, and the product was represented by Pt-MCM-41.

The XRPD pattern of the obtained Pt-MCM-41 is shown in Fig. 2, which shows that the calcined Pt-MCM-41 has a 2θ of 2.43° at a (100) plane and a d-spacing value of 3.63 nm, as observed from the graph. The intensity of the diffraction front is weak, indicating that the Pt-MCM-41 still has a hexagonal symmetrical structure. Fig. 7 is a TEM image of the obtained Pt-MCM-41. It can be seen that when the iron metal (ion) is modified (implanted) into the MCM-41 skeleton, the crystallinity of the MCM-41 is deteriorated, and the hexagonal arrangement is less likely to be seen. Hole accumulation structure. The BET specific surface area of the obtained Ti-MCM-41 measured by nitrogen absorption was about 1138 m ² /g. The average pore diameter obtained from Fig. 3 was 2.59 nm, and the average pore volume was 0.70 cm ³ /g.

Next, please refer to Figure 9 for the treatment of chlorine-containing volatile organic compounds with Pt-MCM-41. The air pump is used to raise the methylene chloride in the impact bottle and mix it at a concentration of 250 ppm to adjust the gas with a float flow meter. The space flow rate is 1800 hr ^-1 , and it is uniformly mixed into the gas mixing tank, and then introduced into the catalytic reactor heating system, heated from 300K to 823K for catalytic reaction, and the gas after the reaction is gas chromatograph ( GC-FID) analysis of the change in concentration before and after the reaction, as shown in Figure 9, the conversion of methylene chloride at 823 K was about 60%.

1‧‧‧Dichloromethane supply steps

2‧‧‧Medium hole catalyst supply steps

3‧‧‧Steps for the treatment of methylene chloride by catalyst incineration

Figure 1 is a flow chart of the steps of the present invention.

Figure 2 XRPD diagram of various catalyst low angles.

Figure 3 The hole volume curve of various catalysts.

Figure 4 MCM-41 magnifies 4*105 times the TEM image.

Figure 5 Fe-MCM-41 magnifies 4*105 times the TEM image.

Figure 6 Ti-MCM-41 magnifies 4*105 times the TEM image.

Figure 7 Pt-MCM-41 magnifies the TEM image of 2.5*105 times.

Figure 8 Blank test of various dichloromethane concentrations.

Figure 9 shows the effect of various catalysts on the conversion of methylene chloride at a dichloromethane influent concentration of 250 ppm and a space velocity of 1800 hr ^-1 .

1‧‧‧Dichloromethane supply steps

2‧‧‧Medium hole catalyst supply steps

3‧‧‧Steps for the treatment of methylene chloride by catalyst incineration

Claims (7)

A method for treating methylene chloride by a mesoporous catalyst, the method comprising the steps of: (a) providing a gas containing dichloromethane (CH ₂ Cl ₂ ); (b) providing an appropriate amount in a sol-gel method and selected from the group consisting of a hole catalyst in Fe-MCM-41, Ti-MCM-41 or Pt-MCM-41; (c) causing the mesoporous catalyst to be incinerated by the catalyst incineration method with the methylene chloride-containing gas. The method of treating a methylene chloride in a hole catalyst according to the first aspect of the patent application, wherein the gas of the step (a) has a concentration of methylene chloride of 100 to 250 ppm, and the space velocity of the gas is 1800~ 9000hr ^-1 . The method for treating a methylene chloride in a hole catalyst according to the first aspect of the patent application, wherein the step (c) is in a temperature range of 373 K to 823 K, and the medium hole catalyst and the methylene chloride are contained. The gas is incinerated. The method for processing a methylene chloride according to the method of claim 1, wherein the mesoporous catalyst is prepared by a sol-gel method, and the preparation method comprises the steps of: (a) preparing a solution. , comprising mixed water, ammonia water and cetyltrimethylammonium bromide (CTMABr); (b) preparing a solution comprising mixed tetraethoxy decane (TEOS) and a metal salt solution, the metal salt solution is selected Prepared from a metal salt of ferric nitrate, titanium tetrabutoxide or potassium hexachloroplatinate; (c) The solution prepared in the step (b) is added dropwise to the solution prepared in the step (a), stirred at room temperature and placed overnight to form a product, and the initial product is rinsed with deionized water. After filtering to a neutral pH value, it was dried in an oven to overnight, and then sintered in a high temperature furnace to obtain a hole catalyst in Fe-MCM-41, Ti-MCM-41 or Pt-MCM-41. The method for preparing a hole catalyst according to the fourth aspect of the invention, wherein the method for preparing a hole catalyst in the Fe-MCM-41 comprises: the step (a), which comprises preparing a solution. 2.5 g of cetyltrimethylammonium bromide (CTMABr) was dissolved in 125 ml of deionized water, 10 ml of ammonia water (28% by weight) was added, and an electromagnetic stirrer was used for 15 minutes at room temperature. The cetyltrimethylammonium bromide is completely dissolved; in the step (b), the metal salt solution is dissolved in 0.94 ml of iron nitrate (Fe(NO ₃ ) ₃ .9H ₂ O). A solution of the iron metal salt is prepared by using an alcohol (Propanol-2), and 5.2 ml of tetraethoxy decane (TEOS) is mixed with the iron metal salt and stirred to prepare a solution of the step (b); The mixture of the step (a) and the step (b) is continuously stirred at room temperature for 2 hours, and dried in an oven at 120 ° C and calcined at 540 ° C for 6 hours in a high temperature furnace to obtain the Fe-MCM- 41 holes in the catalyst. The method for preparing a hole catalyst according to the fourth aspect of the invention, wherein the step of preparing the hole catalyst in the Ti-MCM-41 comprises: the step (a), which comprises preparing a solution. 2.5 g of cetyltrimethylammonium bromide (CTMABr) was dissolved in 125 ml of deionized water, 10 ml of ammonia water (28% by weight) was added, and an electromagnetic stirrer was used for 15 minutes at room temperature. Prepared by completely dissolving cetyltrimethylammonium bromide; in step (b), the metal salt solution is dissolved in 2 ml of titanium tetrabutoxide (Ti(OC ₄ H ₉ ) ₄ ) in 10.4 ml. A solution of the titanium metal salt is prepared from propanol (Propanol-2), and 5.2 ml of tetraethoxy decane (TEOS) is mixed with the titanium metal salt and stirred to prepare a solution of the step (b); c), the mixture of the step (a) and the step (b) is continuously stirred at room temperature for 2 hours, and dried in an oven at 120 ° C and calcined at 540 ° C for 6 hours in a high temperature furnace to obtain the Ti-MCM. -41 hole in the catalyst. The method for preparing a hole catalyst according to the fourth aspect of the invention, wherein the step of preparing the hole catalyst in the Pt-MCM-41 comprises: the step (a), which comprises preparing a solution. Prepare 1.2 g of cetyltrimethylammonium bromide (CTMABr) dissolved in 60 ml of deionized water, add 18.8 ml of ammonia water (28 wt%), and use an electromagnetic stirrer for 15 minutes at room temperature. The cetyltrimethylammonium bromide is completely dissolved; in the step (b), the metal salt solution is prepared by dissolving 0.1 g of potassium hexachloroplatinate (K ₂ PtCl ₆ ) in 2.5 ml of deionized water. a platinum metal salt solution, and taking 5.3 ml of tetraethoxy decane (TEOS) and the titanium metal salt are mixed and stirred to obtain the solution of the step (b); the step (c) is the step (a) The mixture of the step (b) was continuously stirred at room temperature for 2 hours, and dried in an oven at 120 ° C and calcined at 540 ° C for 6 hours in a high temperature furnace to obtain a pore catalyst in the Pt-MCM-41.