CN111495357A - Catalyst with ultralow noble metal content as well as preparation method and application thereof - Google Patents
Catalyst with ultralow noble metal content as well as preparation method and application thereof Download PDFInfo
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- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
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- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/8668—Removing organic compounds not provided for in B01D53/8603 - B01D53/8665
Abstract
The invention discloses an ultralow-precious-metal-content catalyst, and a preparation method and application thereof. The preparation method comprises the following steps: reducing agent and TiO2Mixing, reducing to obtain carrier R-TiO2(ii) a The carrier R-TiO is added2Dissolving the noble metal salt, mixing and stirring the solution and the noble metal salt, and reducing the noble metal salt into elemental metal to obtain M/R-TiO2. The invention is realized by the pair of carrier TiO2The method has the advantages that defect site modification is carried out, the excellent removal effect of low-concentration formaldehyde can be realized under extremely low loading capacity, the removal efficiency can reach 100%, the removal efficiency of formaldehyde under the conditions of 10-40 ℃ and 30-70% of humidity can reach 100%, the treatment effect on low-concentration formaldehyde, medium-concentration formaldehyde and high-concentration formaldehyde is obvious, the stability is good, the deactivation resistance of a catalyst is strong, the service life is long, and the method has industrial application performanceCan be widely applied to the catalytic oxidation of indoor formaldehyde.
Description
Technical Field
The invention relates to the technical field of catalyst preparation, in particular to an ultralow-precious-metal-content catalyst, and a preparation method and application thereof.
Background
Formaldehyde (HCHO), which is considered to be a harmful gaseous pollutant widely present in indoor environments, is exposed to indoor air containing formaldehyde for a long time, even at low concentrations, resulting in serious health problems including nasal tumors, irritation of eye and respiratory mucosa, skin irritation, concentration reduction and immunity reduction, and thus removal of formaldehyde from indoor air is extremely important in order to reduce public health risks. The catalytic oxidation method is a common method for removing formaldehyde, and mainly comprises two main types of noble metals and non-noble metals. Compared with non-noble metal catalysts, noble metal catalysts have better characteristics of catalyzing and oxidizing formaldehyde at low temperature, but the cost is higher.
The existing formaldehyde catalyst mainly comprises Na-doped Pd/TiO2Catalyst and Mn-doped Pt/TiO2Catalysts, and the like. Na-doped Pd/TiO2The preparation of the catalyst generally comprises the following steps: (1) adding TiO into the mixture2With NaNO3And Pd (NO)3)2Co-dipping with an aqueous solution; (2) after impregnation, excess water was removed in a rotary evaporator at 60 ℃; (3) the sample was dried at 110 ℃ overnight and then calcined at 400 ℃ for 2 hours; (4) the sample was incubated with H at 350 deg.C2And reducing for 30 minutes. The sample is calcined at 400 ℃ and reduced at 350 ℃, the reduction temperature is high, the energy consumption is high, the load capacity of Pd is 1%, the content of noble metal is high, and the cost is high. Mn doped Pt/TiO2The preparation of the catalyst generally comprises the following steps: (1) 10g of TiOSO are stirred vigorously4And 0.5g KMnO4Dissolving the powder in 500m L deionized water, (2) transferring the solution obtained in the step (1) into an autoclave, heating the solution at 160 ℃ for 24 hours, and (3) filtering the obtained green solid, washing the green solid with water, and finally calcining the powder at 450 ℃ for 4 hours to obtain the carrier Mn-TiO2(ii) a (4) 2g of Mn-TiO2Ultrasonic dispersion in 100m L containing 0.051mmol H2PtCl6To obtain a suspension, (5) diluting 0.5g H with 20m L of water2O2(30 wt%) and then added dropwise to the above suspension under vigorous stirring at 60 ℃; (6) the resulting solid was filtered, washed with water and dried at 110 ℃ overnight; (7) finally, the powder obtained is purified by means of pure H at 350 ℃2The treatment was carried out for 4 hours. At lower Pt contents, e.g. 0.1 and 0.3 wt% Pt/Mn-TiO2The catalyst has almost no catalytic activity, the activity test is carried out under the condition that the mass space velocity is 6000m L/(g.h), the test condition is mild, and for the high-activity catalyst, the weight percent of Pt/Mn-TiO is 0.5 percent2When the mass space velocity is increased by 12000m L/(g, L))，CO2The yield is reduced from 100% to 60%; the sample needs to be reduced for 4 hours at 350 ℃, the reduction temperature is high, the required time is long, and the energy consumption is large.
CN101380574A discloses a catalyst for completely oxidizing formaldehyde under room temperature catalysis, which comprises three parts of a porous inorganic oxide, a precious metal component and an auxiliary agent component, wherein the precious metal component is one of platinum, rhodium, palladium, gold and silver, but the precious metal component can realize 100% conversion of formaldehyde when loading platinum metal, when loading palladium is 1%, the corresponding formaldehyde conversion rate is only 73%, the carbon dioxide selectivity is only 92%, and obviously the improvement of the catalytic performance and the improvement of the service life of ultralow loading of palladium metal cannot be realized.
Disclosure of Invention
The invention aims to solve the technical problems of large loading capacity, poor inactivation resistance, short service life and incapability of aiming at the defects and the defects of low-concentration formaldehyde treatment of the existing noble metal catalyst, and provides a preparation method of the catalyst with ultralow noble metal content.
The invention aims to provide a catalyst M/R-TiO with ultra-low precious metal content2。
Another object of the present invention is to provide an ultra-low noble metal content catalyst M/R-TiO2The application of the catalyst in the catalytic oxidation of formaldehyde at room temperature.
The above purpose of the invention is realized by the following technical scheme:
a preparation method of an ultralow-precious-metal-content catalyst comprises the following steps:
s1, preparing a carrier R-TiO2: reducing agent and TiO2After mixing, reducing for 20-60 min at 100-300 ℃, removing unreacted reducing agent to obtain the carrier R-TiO2；
S2, preparing the catalyst with ultralow noble metal content: the carrier R-TiO is added2Dissolving the noble metal salt, mixing and stirring the solution, reducing the noble metal salt into elemental metal, and drying a reaction product to obtain the catalyst M/R-TiO with ultralow noble metal content2；
The reducing agent in S1 is sodium borohydride, sodium borohydride and TiO2The mass ratio of (A) to (B) is 1: 3-7;
the loading amount of the noble metal in the S2 is 0.05-0.5% by mass.
The noble metal can be palladium, platinum and other formaldehyde catalytic supported noble metals.
The carrier R-TiO prepared by S1 in the preparation method of the catalyst with ultra-low precious metal content2O in the process of degrading formaldehyde for the purpose of reducing titanium dioxide rich in defect sites such as oxygen vacancies2And H2O can be readily adsorbed and activated at oxygen vacancies, thereby producing surface adsorbed oxygen. Meanwhile, a large number of defect sites enhance the interaction between the carrier and the noble metal, and modulate the electronic structure on the surface of the noble metal nano particle, so that the noble metal nano particle is easier to adsorb and dissociate oxygen, and further the capability of capturing and catalyzing formaldehyde molecules is improved.
The existing preparation method of the noble metal-loaded catalyst rarely involves modification of related carriers, the integral reaction temperature is above 450 ℃, the reaction temperature is high, and the energy consumption is high. The invention is directed to a noble metal-loaded support TiO2The defect site modification is carried out, the carrier treatment temperature is also 100-300 ℃, the reduction temperature is lower, and the preparation energy consumption is reduced. By loading the noble metal on the titanium dioxide carrier with the defect sites, the catalyst can show better formaldehyde degradation efficiency under the condition of extremely low loading.
In the reaction of catalytic oxidation of formaldehyde, the function of the defect sites of the catalyst is as follows: the positions of water molecules are dissociated to form two OH groups which can react with formate substances, and meanwhile, the defect positions can reduce the chemical adsorption energy of oxygen molecules which are adsorbed on reduced TiO2On the surface of (a), accepts electrons and then converts them into active oxygen, thereby degrading formaldehyde.
The key to modification of the carrier defect site in S1 is the selection of a reducing agent, the reaction energy consumption required by different reducing agents is different, and the corresponding reduction temperatures are different. Under high temperature and high energy consumption, oxygen in the carrier crystal lattice can be easily dissipated, and the proper reducing agent is selected to reduce the required energy consumption and the preparation energy consumption of the catalyst.
The reducing agent in the S1 is sodium borohydride, sodium borohydride and TiO2The mass ratio of (A) to (B) is 1: 3-7. Too small amount of reducing agent, short reaction time with reducing agent, TiO2The sample surface generates few defect sites, and the catalytic oxidation effect on formaldehyde is poor. When the reduction degree of the catalyst is too high, the dosage of the reducing agent is large, the contact time is long, and the reduced TiO2O adsorbed on the surface2May be reduced and electrons may be trapped by excess surface oxygen vacancies, thereby preventing the conversion of oxygen molecules to active oxygen and also contributing to the catalytic oxidation of formaldehyde by the catalyst.
In order to further enhance the catalytic oxidation effect, the reduction temperature in S1 is preferably 300 ℃ and the reduction time is preferably 30 min.
To ensure the carrier defect site modification effect, sodium borohydride and TiO 12Is preferably 1: 4.
Preferably, the loading amount of the noble metal in the S2 is 0.25-0.5% by mass
Preferably, in S2, the noble metal salt is reduced to the elemental metal by liquid phase reduction, and the reducing agent is NaBH4Solution, NaBH4The molar ratio of the noble metal to the noble metal is 15-30: 1. The reduction temperature is 20-30 ℃ at normal temperature, and the reduction time is 1.5-3 h.
Preferably, in S2, the noble metal salt is reduced to the elemental metal by hydrogen, the reduction time is 30min, the reduction temperature is 300 ℃, the gas flow is 300-600 m L/min, the increase of the amount of the impurity ions in the final catalyst can be reduced by hydrogen reduction treatment, and the formaldehyde catalytic oxidation effect of the catalyst is improved.
The invention also provides the catalyst M/R-TiO with the ultralow noble metal content prepared by the preparation method of the catalyst with the ultralow noble metal content2。
The catalyst M/R-TiO with ultralow noble metal content2The application in catalytic oxidation of formaldehyde is also within the scope of the invention.
The catalyst M/R-TiO with ultralow noble metal content2Can be used for the catalytic oxidation treatment of the conventional indoor formaldehyde and has good effect on the indoor low-concentration formaldehyde of 0.08ppmThe catalytic effect is preferably 0.08 to 100 ppm.
The ultra-low precious metal content catalyst M/R-TiO of the application is in the normal ambient humidity range2The indoor formaldehyde can be well catalyzed and degraded, and the applicable environment humidity is preferably 30-70% in application.
Furthermore, under the environment with the humidity of 50-60%, M/R-TiO2The catalyst has a better catalytic oxidation effect, and the treatment effect on formaldehyde can reach 90-100%.
The catalyst M/R-TiO with ultralow noble metal content is used under normal indoor temperature condition of 10-40 DEG C2The catalyst has good catalytic oxidation effect, and the treatment effect on formaldehyde is 50-100%.
When the environmental temperature of the treatment reaches more than 30 ℃, the catalyst M/R-TiO of the application2The catalytic oxidation effect on formaldehyde can reach 100%.
More preferably, the application has the environment humidity of 50% and the environment temperature of 30-40 ℃.
The catalyst M/R-TiO with ultralow noble metal content2The catalyst has excellent effect on removing formaldehyde with concentration of less than 100ppm, the removal efficiency of the formaldehyde at normal temperature can reach 100%, the stability is good, the stabilization time can reach 18h, the loading capacity of the noble metal of the catalyst is low, the cost is relatively low, and the good catalytic activity of the ultra-low loading capacity of the noble metal is realized.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a catalyst M/R-TiO with ultra-low noble metal content2By applying to the support TiO2The modified carrier is modified by defect sites, a large number of defect sites are manufactured on the carrier, the interaction between the carrier and the noble metal palladium is enhanced, the electronic structure on the surface of the noble metal nano particle is modulated, the noble metal nano particle is easier to adsorb and dissociate oxygen, the capability of capturing and catalyzing formaldehyde molecules is further improved, 100% of formaldehyde with the concentration of less than 100ppm can be removed under the condition of extremely low load of 0.05-0.5%, and the modified carrier has good catalytic activity.
The ultra-low noble metal content of the inventionCatalyst M/R-TiO2The formaldehyde removal efficiency can reach 100% under the conditions that the temperature is 10-40 ℃ and the humidity is 30-70%; the time required by degradation aiming at the ultralow indoor formaldehyde content of 0.08ppm is only 9s, and the treatment effect is obvious; aiming at high-concentration formaldehyde of 100ppm, the catalyst has strong inactivation resistance, can be stabilized for 18 hours, can be stabilized for 72 hours by 20ppm, has long service life, has industrial application capability, and can be widely applied to catalytic oxidation of indoor formaldehyde.
Detailed Description
The present invention will be further described with reference to specific embodiments, but the present invention is not limited to the examples in any way. The starting reagents employed in the examples of the present invention are, unless otherwise specified, those that are conventionally purchased.
Example 1
A preparation method of an ultralow-precious-metal-content catalyst comprises the following steps:
s1, preparing a carrier R-TiO2: reacting sodium borohydride and TiO2Mixing, keeping at 300 deg.C for 30min, removing unreacted sodium borohydride to obtain carrier R-TiO2The mass ratio of sodium borohydride to P25 is 1:4
S2, preparing the catalyst with ultralow noble metal content: weighing 1g of carrier R-TiO2、0.0025gPd(NO3)2Dissolving, mixing and stirring, wherein NaBH is added in the stirring process4The solution is added to the mixture solution (nNaBH)4-nPd ═ 20: 1) reducing for 2h at 25 deg.C, stirring, drying the mixture in water bath at 80 deg.C, drying the obtained powder at 80 deg.C overnight, and recording the obtained catalyst as 0.1Pd/R-TiO2The Pd loading amount is 0.1 percent by mass.
Example 2
A preparation method of an ultralow-precious-metal-content catalyst comprises the following steps:
s1, preparing a carrier R-TiO2: reacting sodium borohydride and TiO2Mixing, keeping at 300 deg.C for 30min, removing unreacted sodium borohydride to obtain carrier R-TiO2The mass ratio of sodium borohydride to P25 is 1:4
S2. preparationUltra low precious metal content catalyst: weighing 1g of carrier R-TiO2、0.0063gPd(NO3)2Dissolving, mixing, stirring, drying the mixture at 80 deg.C in water bath, drying the obtained powder at 80 deg.C overnight, reducing with hydrogen at 300 deg.C for 30min at gas flow rate of 500m L/min, and collecting the obtained catalyst as 0.25Pd/R-TiO2The Pd loading amount is 0.25 percent by mass.
Example 3
A preparation method of an ultralow-precious-metal-content catalyst comprises the following steps:
s1, preparing a carrier R-TiO2: reacting sodium borohydride and TiO2Mixing, keeping at 300 deg.C for 30min, removing unreacted sodium borohydride to obtain carrier R-TiO2The mass ratio of sodium borohydride to P25 is 1:4
S2, preparing the catalyst with ultralow noble metal content: weighing 1g of carrier R-TiO2、0.0125gPd(NO3)2Dissolving, mixing, stirring, drying the mixture at 80 deg.C in water bath, drying the obtained powder at 80 deg.C overnight, reducing with hydrogen at 300 deg.C for 30min at gas flow rate of 500m L/min, and collecting the obtained catalyst as 0.5Pd/R-TiO2The Pd loading amount is 0.5 percent by mass.
Example 4
A preparation method of an ultralow-precious-metal-content catalyst comprises the following steps:
s1, preparing a carrier R-TiO2: reacting sodium borohydride and TiO2Mixing, keeping at 300 deg.C for 30min, removing unreacted sodium borohydride to obtain carrier R-TiO2The mass ratio of sodium borohydride to P25 is 1:4
S2, preparing the catalyst with ultralow noble metal content: weighing 1g of carrier R-TiO2、0.0125gPd(NO3)2Dissolving, mixing and stirring, wherein NaBH is added in the stirring process4The solution is added to the mixture solution (nNaBH)4-nPd ═ 20: 1) reducing for 2 hr at 25 deg.C, stirring, drying the mixture at 80 deg.C in water bath, and pulverizing at 80 deg.CAfter drying overnight, the catalyst obtained was reported as 0.5Pd/R-TiO2The Pd loading amount is 0.5 percent by mass.
Example 5
Initial concentration change of formaldehyde gas
Catalyst Pd/R-TiO with ultralow noble metal content2Initial concentrations of formaldehyde were 0.08, 20 and 100ppm, mass space velocity was 120000m L/g h, reaction temperature was 30 ℃, catalyst loading was 0.05g, ambient humidity (RH) was 50%, and gaseous HCHO was generated by dry air passing through a water bath of paraformaldehyde in a round bottom flask at 40 ℃.
The formaldehyde concentration detection method comprises the following steps: the low concentration formaldehyde is detected by PTR-TOF-MS, and the medium and high concentration formaldehyde is detected by a photoacoustic spectrometer.
The results of the catalytic performance test are shown in tables 1 and 2 below:
TABLE 1
| Serial number | Time/s required for 0.08ppm degradation |
| Example 1 | 36s |
| Example 2 | 17s |
| Example 3 | 9s |
| Example 4 | 19s |
When the indoor formaldehyde concentration reaches 0.08ppm (0.1 mg/m)3) In the meantime, the formaldehyde pollution has peculiar smell and uncomfortable feeling, can stimulate eyes, cause lacrimation, and cause throat discomfort or pain, and is a common concentration of indoor formaldehyde pollution. Meanwhile, the catalyst has good stability at low concentration, maintains catalytic activity for a long time, and does not reflect the difference of a system any more, because the time required for degrading 0.08ppm of formaldehyde is selected as a standard point for checking the treatment effect of the catalyst on the formaldehyde in a low-concentration room. As can be seen from the above data, the Pd/R-TiO of the present application2The catalyst has a rapid treatment effect on low-concentration indoor formaldehyde, and the catalytic oxidation degradation effect is remarkable.
TABLE 2
The formaldehyde degradation efficiency of the catalyst can be seen from the formaldehyde conversion rate, the higher the conversion rate is, the better the catalytic degradation effect is, and the longer the stabilization time is, the catalyst has the advantages of strong inactivation resistance, long service life and industrial application capability. The catalysts of examples 1-4 all exhibited good formaldehyde conversion at different initial formaldehyde concentrations, with 0.5Pd/R-TiO treated by hydrogen reduction2Best stability of-H, shortest time required to reduce formaldehyde from initial concentration of 0.08ppm to 0.03ppm, over H2The reduction treated catalyst can achieve better effect under lower load and has good environmental adaptability.
Example 6
Change of ambient humidity
Catalyst Pd/R-TiO with ultralow noble metal content2The formaldehyde is applied to catalytic oxidation of formaldehyde at room temperature, the performance of the formaldehyde is tested in a fixed bed continuous flow reactor with the inner diameter of 6mm, the initial concentration of the formaldehyde is 100ppm, the mass space velocity is 120000m L/gh, the reaction temperature is 30 ℃, the dosage of the catalyst is 0.05g, and the environmental humidity (RH) is 30 percent respectively40%, 50%, 60% and 70%, gaseous HCHO was generated by passing dry air through paraformaldehyde in a water bath in a round bottom flask at 40 ℃.
The formaldehyde concentration detection method comprises the following steps: and (5) detecting by using a photoacoustic spectrometer.
The results of the catalytic performance test are shown in Table 3 below
From the above results, it can be seen that when the ambient humidity is gradually increased from 30% to 70%, the formaldehyde conversion rates of the four catalysts all show a tendency of increasing first and then decreasing, and 50% humidity is most suitable, and the best degradation efficiency is obtained. The reason for this is that water molecules, which act as a hole trapping agent, can generate a strong oxidant, OH, which is beneficial to the catalytic degradation of formaldehyde. But when the humidity is too high, because of TiO2The catalyst has hydrophilicity, and water molecules and formaldehyde molecules are subjected to competitive adsorption on the surface of the catalyst, so that the formaldehyde adsorption quantity is reduced. In activity tests of five environmental humidities, all the tests are 0.5Pd/R-TiO treated by hydrogen reduction2-H shows the best catalytic activity, while the 0.5Pd/R-TiO treated by liquid phase reduction2Y with only 0.25Pd/R-TiO2H showed similar activity results.
Example 7
Change of ambient temperature
Catalyst Pd/R-TiO with ultralow noble metal content2The initial concentration of formaldehyde was 100ppm, the mass space velocity was 120000m L/gh, the reaction temperature was divided into 10 ℃, 20 ℃, 30 ℃ and 40 ℃, the catalyst dosage was 0.05g, the ambient humidity (RH) was 50%, and gaseous HCHO was generated by passing dry air through paraformaldehyde through a water bath in a round bottom flask at 40 ℃.
The formaldehyde concentration detection method comprises the following steps: and (5) detecting by using a photoacoustic spectrometer.
The results of the catalytic performance tests are shown in Table 4 below
The higher the reaction temperature is, the faster the adsorption, desorption and mass transfer rates are, which is beneficial to the catalytic reaction. As can be seen from the results in Table 4, the four catalysts showed excellent catalytic activity at a reaction temperature of 30 ℃ except for 0.1Pd/R-TiO2The other three except the 92 percent of-H conversion rate realize the complete removal of formaldehyde. 0.5Pd/R-TiO treated by hydrogen reduction with further reduction of the reaction temperature2H always showed the highest conversion of formaldehyde, 0.5Pd/R-TiO treated by liquid phase reduction2-Y and 0.25Pd/R-TiO2H showed similar activity results.
The above experimental results show that hydrogen and Pd/R-TiO treated by liquid phase reduction2The catalyst has good formaldehyde catalytic activity, but the catalyst Pd/R-TiO is subjected to hydrogen reduction treatment2the-H can achieve the same effect as liquid phase reduction under the condition of lower noble metal loading, has strong environmental adaptability and can keep good activity at lower temperature and in a wider humidity range.
Example 8
A preparation method of an ultralow-precious-metal-content catalyst comprises the following steps:
s1, preparing a carrier R-TiO2: reacting sodium borohydride and TiO2Mixing, keeping at 300 deg.C for 30min, removing unreacted sodium borohydride to obtain carrier R-TiO2The mass ratio of sodium borohydride to P25 is 1:4
S2, preparing the catalyst with ultralow noble metal content: 1g of the support R-TiO is taken2And 32.89u L of chloroplatinic acid solution with the concentration of 0.076 mol/L mol is added into deionized water to be stirred, the mixture is dried in a water bath at the temperature of 80 ℃ after stirring is finished, the obtained powder is dried at the temperature of 80 ℃ overnight, and then is subjected to hydrogen reduction treatment at the temperature of 300 ℃ for 30min, the gas flow is 500m L/min, and the obtained catalyst is marked as 0.05Pt/R-TiO2The Pt loading was 0.05% by mass.
Example 9
Example 8 ultra Low noble Metal content catalyst Pt/R-TiO2At room temperatureFormaldehyde initial concentration was 20ppm, mass space velocity was 120000m L/g h, reaction temperature 30 ℃, catalyst usage was 0.1g, ambient humidity (RH) was 50%, gaseous HCHO was generated by dry air passing through a water bath of paraformaldehyde in a round bottom flask at 40 ℃.
The formaldehyde concentration detection method comprises the following steps: detected by a photoacoustic spectrometer.
The results of the catalytic performance test are shown in table 5 below:
TABLE 5
| Serial number | Conversion (%) | Stabilization time (h) |
| Example 8 | 68 | 12h |
It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.
Claims (10)
1. The preparation method of the catalyst with ultralow noble metal content is characterized by comprising the following steps:
s1, preparing a carrier R-TiO2: reducing agent and TiO2After mixing, reducing for 20-60 min at 100-300 ℃, removing unreacted reducing agent to obtain the carrier R-TiO2；
S2, preparing the catalyst with ultralow noble metal content: the carrier R-TiO is added2Dissolving the noble metal salt, mixing and stirring the solution, reducing the noble metal salt into elemental metal, and drying a reaction product to obtain the catalyst M/R-TiO with ultralow noble metal content2；
The reducing agent in S1 is sodium borohydride, sodium borohydride and TiO2The mass ratio of (A) to (B) is 1: 3-7;
the loading amount of the noble metal in the S2 is 0.05-0.5% by mass.
2. The method for preparing the catalyst with ultra-low noble metal content according to claim 1, wherein the noble metal loading in S2 is 0.25-0.5% by mass.
3. The method of claim 1, wherein the noble metal salt is reduced to elemental metal by hydrogen gas in S2 for 30min at 300 ℃.
4. The catalyst M/R-TiO with ultra-low noble metal content prepared by the method for preparing the catalyst with ultra-low noble metal content according to any one of claims 1 to 32。
5. The ultra-low noble metal content catalyst M/R-TiO of claim 42The application in catalytic oxidation of formaldehyde.
6. The use according to claim 5, wherein the initial concentration of formaldehyde in the use is from 0.08 to 100 ppm.
7. The use according to claim 5, wherein the use has an ambient humidity of 30 to 70%.
8. The use according to claim 7, wherein the use has an ambient humidity of 50 to 60%.
9. The use according to claim 5, wherein the ambient temperature in said use is 10 to 40 ℃.
10. The use according to claim 9, wherein the use has an ambient humidity of 50% and an ambient temperature of 30 to 40 ℃.
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| CN113231077A (en) * | 2021-05-12 | 2021-08-10 | 昆明理工大学 | Preparation method and application of defect-rich carrier interface reduction anchoring precious metal catalyst |
| CN115814786A (en) * | 2021-09-17 | 2023-03-21 | 光大环境修复(江苏)有限公司 | Chlorine poisoning resistant CVOCs removal catalyst and preparation method thereof |
| CN115245823A (en) * | 2022-01-25 | 2022-10-28 | 昆明理工大学 | Defected mixed crystal TiO 2 Catalyst, preparation method and application thereof |
| CN115245823B (en) * | 2022-01-25 | 2024-01-23 | 昆明理工大学 | Defect mixed crystal form TiO 2 Catalyst, preparation method and application thereof |
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