Cooking utensil with good oil smoke catalytic effect

Abstract

The invention discloses a cooking utensil with a good oil smoke catalysis effect, and belongs to the technical field of cooking utensils. The cooking utensil comprises a cooking cavity, a hot air assembly and a catalysis module, the hot air assembly comprises a hot air fan and a heating piece, the catalysis module is arranged adjacent to the heating piece, hot air generated by the hot air assembly is input into the cooking cavity to cook food materials, and the catalysis module is used for conducting catalytic decomposition on oil smoke close to and / or flowing through the catalysis module. The catalytic module comprises a porous material and a catalyst attached to the surface of the porous material, the catalyst comprises a catalyst carrier and a combustion catalyst attached to the surface of the catalyst carrier, the catalyst carrier is a gamma-alumina / ZSM-5 composite, and the gamma-alumina / ZSM-5 composite is prepared from pseudo-boehmite and ZSM-5 in a weight ratio of (1-7): (3-9). The catalyst carrier adopted by the catalytic module in the cooking utensil is moderate in pore channel, the catalytic purification effect on oil smoke gas can be improved, cracking catalysis can be conducted on oil dirt macromolecules, and the service life of the catalyst is prolonged.

Description

Technical Field

[0001] The present application relates to a cooking appliance with good catalytic effect on lampblack, belonging to the technical field of cooking appliances. Background Art

[0002] Cooking appliances such as air fryers and ovens generate extremely fine liquid particles and volatile organic compounds (VOCs) during the cooking process. The extremely fine liquid particles mainly belong to organic compound types such as hydrocarbons and hydrocarbon oxides decomposed from grease; the main components of VOCs are in the form of small molecules with short carbon chains, and the types of harmful substances include alkanes, alkenes, polycyclic aromatic hydrocarbons, alcohols, aldehydes and ketones, acids, esters, etc. Therefore, removing extremely fine liquid particles and VOCs in lampblack can effectively solve the lampblack emission of cooking appliances.

[0003] Generally, extremely fine liquid particles and VOCs in lampblack need to be directly oxidized and decomposed into carbon dioxide and water at temperatures above 500°C. The catalytic oxidation method is one of the effective solutions for purifying lampblack. The catalytic oxidation method uses a catalyst to catalytically purify lampblack, which can oxidize and decompose lampblack VOCs into water and carbon dioxide at a low temperature of 200 - 300°C, achieving harmless emission.

[0004] However, the current catalyst materials are not completely applicable for removing lampblack in cooking appliances such as air fryers and ovens. The main reason is that the centrifugal fan in the air fryer and oven rotates at a high speed (up to 3200 revolutions per minute), so the gas convection speed inside the appliance is fast, reaching 2 - 6 m / s. This high rotation speed makes the gas containing lampblack pass through the catalyst material faster. Due to the small specific surface area and small pore size of the existing catalyst, the organic substances in the lampblack flow away before they have time to undergo catalytic reaction when passing through the catalyst. For example, the maximum space velocity of the catalyst in Patent CN1140343C is 25000 / h, and the converted air flow velocity is much less than 1 m / s, which does not match the gas convection speed inside the appliance and cannot effectively purify the lampblack.

[0005] And currently, the catalyst used in the catalytic oxidation method only has a certain purification effect on the gaseous VOC components in lampblack and cannot remove the oil scale formed by cooling and condensation. For example, the catalyst in Patent CN100518932C can only remove gaseous VOC substances. During the use of cooking, oil scale will inevitably condense. The condensation of this oil scale will cover the catalyst, resulting in catalyst deactivation or reducing the catalyst activity and lifespan. Summary of the Invention

[0006] To solve the above problems, a cooking appliance with good oil fume catalytic effect is provided. In this cooking appliance, the pore channels of the catalyst carrier used in the catalytic module are of moderate size, which can not only ensure the smooth flow of the high-speed flowing oil fume gas in the pore channels and sufficient contact with the catalyst, but also extend the residence time of the oil fume gas in the pore channels, improve the purification rate of the oil fume gas, and can also carry out cracking catalysis on the macromolecules of oil scale, thereby extending the service life of the catalyst.

[0007] The present application provides a cooking appliance with good oil fume catalytic effect, including a cooking cavity, a hot air component and a catalytic module. The hot air component includes a hot air fan and a heating element. The catalytic module is arranged adjacent to the heating element. The hot air component generates hot air and inputs it into the cooking cavity to cook the food materials. The catalytic module is used for catalytic decomposition of the oil fume close to and / or flowing through it. The catalytic module includes a porous material and a catalyst attached to the surface of the porous material. The catalyst includes a catalyst carrier and a combustion catalyst attached to the surface of the catalyst carrier. The catalyst carrier is a γ-alumina / ZSM-5 composite, and the γ-alumina / ZSM-5 composite is prepared from pseudoboehmite and ZSM-5 with a weight ratio of 1-7:3-9.

[0008] In the present application, the catalyst uses a γ-alumina / ZSM-5 composite as the catalyst carrier. The catalyst carrier is a porous material and can support the combustion catalyst. The catalyst carrier is prepared from pseudoboehmite and ZSM-5 with a weight ratio of 1-7:3-9. Although the specific surface area of ZSM-5 molecular sieve is large, its pore diameter is small, only about 0.6 nm. By forming γ-alumina on ZSM-5 with aluminum pseudoboehmite, ZSM-5 can be modified. Therefore, the pore diameter of ZSM-5 can be adjusted to increase the entry of VOC molecules into the pore channels and carry out catalytic oxidation reaction with the combustion catalyst in the pore channels to achieve the purification of oil fume. ZSM-5 has acidic sites that can crack oil scale, reduce oil scale adhesion, and avoid catalyst deactivation.

[0009] In the present application, the porous material can be one or more of foam metal materials, porous ceramic materials, porous zeolite materials, and porous silica materials, and its shape can be spherical, sheet-shaped or honeycomb-shaped, etc. The porous material can also be understood as a porous structure made of a metal sheet material, such as a honeycomb structure, which can increase the contact area between the catalyst and the oil fume, thereby better promoting the catalytic combustion of the oil fume. It can be understood that the porous material in the present application is known to those skilled in the art.

[0010] Optionally, the γ-alumina / ZSM-5 composite is prepared from pseudoboehmite and ZSM-5 with a weight ratio of 3-6:4-7.

[0011] Preferably, the γ-alumina / ZSM-5 composite is prepared from pseudoboehmite and ZSM-5 with a weight ratio of 4-5:5-6.

[0012] Optionally, the specific surface area of ​​ZSM-5 is greater than 350 m 2 / g, and the average particle size is 50-100nm.

[0013] Optionally, the specific surface area of ​​the γ-alumina / ZSM-5 complex is 170-330 m 2 / g, pore size is 1.1-16nm.

[0014] For the oil fume gas in appliances such as air fryers and ovens, if the pore size of the catalyst carrier is too small, the amount of oil fume gas entering the catalyst carrier is limited, limiting the amount of oil fume gas purification, and oil stains can easily clog the pores, reducing the service life of the overall catalyst; if the pore size of the catalyst carrier is too large, although the oil fume gas can enter the catalyst carrier, with the high-speed flow of the oil fume gas, the oil fume gas that has just entered the catalyst carrier will flow out, and the residence time in the catalyst carrier will be shortened, thereby reducing the purification effect of the catalytic module on the oil fume.

[0015] The above-mentioned ratio of pseudo-boehmite and ZSM-5 used in this application can obtain a γ-alumina / ZSM-5 complex with a moderate specific surface area and pore size, and a purification channel connected by pores is formed between the γ-alumina and ZSM-5, which is suitable for the high-speed flow of oil fume gas in air fryers, ovens, etc. in the pores of the γ-alumina / ZSM-5 complex. It not only increases the amount of oil fume gas entering the catalyst carrier, but also prolongs the residence time of the oil fume gas in the catalyst carrier, which is convenient for the oil fume gas and the combustion catalyst to fully react, improve the purification effect of the oil fume and the service life of the catalyst. And after ZSM-5 is modified by γ-alumina, it can still crack the macromolecular oil scale in the oil fume, and can make the oil scale generate low molecular weight VOC gas, which is further catalytically oxidized and degraded, reducing the adhesion of the oil scale to the catalyst carrier, thereby prolonging the life of the catalyst.

[0016] Optionally, the combustion catalyst is any one or a combination of a noble metal catalyst, a non-noble metal oxide catalyst and a transition metal oxide catalyst.

[0017] The above combustion catalyst can reduce the catalytic temperature and can catalytically oxidize VOCs to generate water and carbon dioxide at low temperatures, thereby improving purification efficiency.

[0018] Optionally, the combustion catalyst is a precious metal catalyst and a non-precious metal oxide catalyst, the non-precious metal oxide catalyst is attached to the surface of the catalyst carrier, and the precious metal catalyst is at least partially dispersed and attached to the surface of the non-precious metal oxide catalyst.

[0019] Noble metal catalysts and non-noble metal oxide catalysts can form catalytically active sites. The noble metal catalysts mainly play a role in catalytically decomposing VOCs and oil fouling, reducing the temperature of the catalyst. The non-noble metal oxides can increase the activity and stability of the noble metal catalysts and have a low cost. Therefore, at least part of the noble metal catalyst being dispersed and attached to the surface of the non-noble metal oxide catalyst can effectively reduce the catalytic temperature and improve the catalytic efficiency of the combustion catalyst.

[0020] Optionally, the noble metal catalyst includes platinum and palladium;

[0021] The weight percentage of platinum in the γ-alumina / ZSM-5 composite is 0.1% - 1.5%;

[0022] The weight percentage of palladium in the γ-alumina / ZSM-5 composite is 0.05% - 1%.

[0023] When platinum < 0.1% and palladium < 0.05%, the catalytic effect of the combustion catalyst is poor and the purification ability for fume gas decreases. When platinum > 1.5% and palladium > 1%, it will increase the cost of the combustion catalyst and the improvement of the catalytic effect of the combustion catalyst is not significant.

[0024] Preferably, the weight percentage of platinum in the γ-alumina / ZSM-5 composite is 0.4% - 1.2%, and the weight percentage of palladium in the γ-alumina / ZSM-5 composite is 0.1% - 0.8%.

[0025] More preferably, the weight percentage of platinum in the γ-alumina / ZSM-5 composite is 0.6% - 1.0%, and the weight percentage of palladium in the γ-alumina / ZSM-5 composite is 0.1% - 0.5%.

[0026] Optionally, the non-noble metal oxide catalyst includes cerium oxide, lanthanum oxide and iron oxide;

[0027] The weight percentage of cerium oxide in the γ-alumina / ZSM-5 composite is 10% - 30%;

[0028] The weight percentage of lanthanum oxide in the γ-alumina / ZSM-5 composite is 0.5% - 5%;

[0029] The weight percentage of iron oxide in the γ-alumina / ZSM-5 composite is 0.5% - 5%.

[0030] Using 10 - 30% cerium oxide in non - noble metal oxides can reduce the temperature at which the catalyst catalyzes VOCs. When the cerium oxide is less than 10%, its effect on reducing the catalytic temperature is limited. When the cerium oxide is more than 30%, it will reduce the specific surface area of the catalyst support and is also not conducive to reducing the catalytic temperature; 0.5% - 5% lanthanum oxide can reduce the catalytic temperature and increase the cracking rate of oil scale. When the content of lanthanum oxide is less than 0.5%, the cracking effect on oil scale becomes poor. When it is more than 5%, the catalytic effect on VOCs becomes poor; iron oxide has a catalytic effect at high temperatures. Using 0.5 - 5% iron oxide can increase the catalytic activity of the combustion catalyst and reduce the cost of the combustion catalyst. When the iron oxide is less than 0.5%, the catalytic effect decreases. When it is more than 5%, there is no improvement in the catalytic efficiency, and it will reduce the proportion of other non - noble metal oxide catalysts, thus reducing the overall catalytic effect of the catalyst.

[0031] Preferably, the weight percentage of cerium oxide in the γ - alumina / ZSM - 5 composite is 15% - 25%, the weight percentage of lanthanum oxide in the γ - alumina / ZSM - 5 composite is 1% - 4%, and the weight percentage of iron oxide in the γ - alumina / ZSM - 5 composite is 1% - 3%.

[0032] More preferably, the weight percentage of cerium oxide in the γ - alumina / ZSM - 5 composite is 18% - 22%, the weight percentage of lanthanum oxide in the γ - alumina / ZSM - 5 composite is 2% - 3%, and the weight percentage of iron oxide in the γ - alumina / ZSM - 5 composite is 1.5% - 3%.

[0033] Optionally, the non - noble metal oxide catalyst further includes calcium oxide, and the weight percentage of calcium oxide in the γ - alumina / ZSM - 5 composite is 0.1% - 5%.

[0034] Calcium oxide is an alkaline earth metal and promotes the cracking of oil molecules at high temperatures. Therefore, it can assist the catalyst support in cracking oil scale and reduce the cost of the catalyst. When the calcium oxide is less than 0.1%, the promoting effect on cracking decreases. When it is more than 5%, the cost increases, and the improvement in the cracking effect of oil scale is not significant.

[0035] Preferably, the weight percentage of calcium oxide in the γ - alumina / ZSM - 5 composite is 0.5% - 3%, and more preferably 1% - 2%.

[0036] As co - catalysts, cerium oxide, lanthanum oxide, iron oxide and calcium oxide in the above non - noble metal oxides can cooperate with each other, jointly improve the activity and stability of the noble metal catalyst, promote the cracking of oil scale molecules, and at the same time increase the loading amount in the γ - alumina / ZSM - 5 composite, thereby improving the purification effect of the catalyst on lampblack and extending the service life of the catalyst.

[0037] Optionally, the method for preparing the catalyst comprises the following steps:

[0038] (1) Mix pseudoboehmite with ZSM-5, add them to an acidic solvent to form a slurry, bake the slurry, impregnate it in an ammonium nitrate solution, wash, dry, and calcine it to obtain a γ-alumina / ZSM-5 composite;

[0039] (2) Immerse the γ-alumina / ZSM-5 composite in a salt solution of the combustion catalyst, dry and calcine it to obtain the catalyst;

[0040] In step (1), through drying and calcination, porous γ-alumina crystals can be formed on ZSM-5 by pseudoboehmite. The pore channels of the γ-alumina crystals are interconnected with those of ZSM-5, thereby obtaining a catalyst support. The combustion catalyst is loaded on the surface of the catalyst support in step (2), which can make full contact with the fume and improve the purification effect on the fume.

[0041] Optionally, the acidic solvent in step (1) is 10%-20% nitric acid, the baking temperature of the slurry is 400-500 °C, the baking time is 3-4 h, the concentration of ammonium nitrate is 1-2.0 mol / L, the calcination temperature is 400-700 °C, the calcination time is 3-8 h, and after calcination, it is cooled and ground to obtain the γ-alumina / ZSM-5 composite.

[0042] Optionally, in step (2), the combustion catalyst includes a noble metal catalyst and a non-noble metal oxide catalyst;

[0043] Immerse the γ-alumina / ZSM-5 composite in a salt solution of a non-noble metal, dry and calcine it to obtain an intermediate, and then immerse the intermediate in a salt solution of a noble metal and calcine it to obtain the catalyst.

[0044] The non-noble metal oxide is first loaded on the surface of the catalyst support, and the noble metal catalyst is dotted on the surface of the non-noble metal oxide catalyst like stars. If the surface of the catalyst support is not completely covered by the non-noble metal oxide catalyst in the intermediate, part of the noble metal catalyst adheres to the surface of the non-noble metal oxide, and part of the noble metal catalyst is located on the surface of the catalyst support. The above steps make the noble metal catalyst fully exposed outside the catalyst support. First, it enables the noble metal catalyst to fully purify the fume, and second, it reduces the production cost of the catalyst.

[0045] Optionally, in step (2), the γ-aluminum oxide / ZSM-5 composite is ball-milled and then impregnated in a nitrate solution of a non-noble metal, dried at 150-200 °C, impregnated 3-5 times, and calcined at 500-700 °C for 2-4 h to obtain an intermediate. The intermediate is impregnated in a nitrate solution of a noble metal and calcined at 500-700 °C for 2-4 h to obtain the catalyst.

[0046] The beneficial effects of the present application include but are not limited to:

[0047] 1. The catalyst carrier of the present application is a porous γ-aluminum oxide / ZSM-5 composite, which has both the catalytic cracking function for large oil dirt molecules and serves as the carrier of the combustion catalyst, and has appropriate pore size and specific surface area, and is suitable for catalytic treatment of high-speed flowing cooking fumes to improve the purification rate of cooking fumes.

[0048] 2. The catalyst carrier of the present application is prepared from pseudoboehmite and ZSM-5 with a weight ratio of 1-7:3-9, which not only increases the amount of cooking fume gas entering the catalyst, but also can extend the residence time of the cooking fume gas in the catalyst, facilitating the full reaction of the cooking fume gas and the combustion catalyst, improving the purification effect of the cooking fumes and the service life of the catalyst.

[0049] 3. The catalyst used in the catalytic module of the present application can realize the catalytic purification of cooking fume VOC at a low temperature below 250 °C, promote its generation of carbon dioxide and water, and can also decompose large molecular oil dirt, avoiding the adhesion and blockage of the catalyst carrier by oil dirt and extending the service life of the catalyst.

[0050] 4. The combustion catalyst used in the catalytic module of the present application can reduce the catalytic temperature. The noble metal catalyst mainly plays a role in catalytic decomposition of VOC and oil dirt, reducing the temperature of the catalyst. The non-noble metal oxide catalyst can enhance the activity and stability of the noble metal catalyst, improve the catalytic effect, and reduce the production cost of the catalyst. Specific Embodiments

[0051] The present application will be described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0052] Unless otherwise specified, the raw materials in the embodiments of the present application are all purchased through commercial channels.

[0053] Example 1

[0054] This embodiment relates to a cooking appliance with good catalytic effect on lampblack, including a cooking cavity, a hot air component and a catalytic module. The hot air component includes a hot air fan and a heating element. The catalytic module is arranged adjacent to the heating element. The hot air component generates hot air and inputs it into the cooking cavity to cook the food materials. The catalytic module is used for catalytic decomposition of the lampblack near and / or flowing through it. Among them, the preparation method of the catalytic module includes the following steps:

[0055] (1) Mix pseudoboehmite and ZSM-5 with a weight ratio of 1:9. The average particle size of ZSM-5 is 50 nm, and the specific surface area > 350 m 2 / g. Add it to 10% nitric acid and mix to form a slurry. Bake it in a high-temperature furnace at 500 °C for 3 h, then immerse it in 1 mol / L ammonium nitrate solution, wash and dry it, and calcine it at 600 °C for 5 h. After cooling, grind it to obtain a γ-alumina / ZSM-5 composite;

[0056] (2) According to the weight conversion of 18% cerium oxide, 2.5% lanthanum oxide, 1.5% iron oxide and 1% calcium oxide into the corresponding weights of cerium nitrate, lanthanum nitrate, iron nitrate and calcium nitrate, weigh and dissolve the above cerium nitrate, lanthanum nitrate, iron nitrate and calcium nitrate in 0.5% nitric acid solution, and immerse the γ-alumina

[0057] / ZSM-5 composite in this solution. After impregnation, dry it at 150 °C, repeat the impregnation 3 times, and then calcine it at 550 °C for 4 h to obtain an intermediate;

[0058] According to the weight conversion of 0.6% platinum and 0.15% palladium into the corresponding weights of platinum nitrate and palladium nitrate, weigh and dissolve the above platinum nitrate and palladium nitrate in 0.5% nitric acid solution, and immerse the intermediate in this solution. After the impregnation is completed, calcine it at 550 °C for 3 h to obtain the catalyst;

[0059] (3) Attach the catalyst to the surface of the porous material to obtain the catalytic module. The porous material is a honeycomb structure made of an iron-chromium-aluminum material plate.

[0060] Examples 2-19 and Comparative Examples 1-3

[0061] The differences between Examples 2-19 and Comparative Examples 1-3 and Example 1 are shown in Table 1 below. The remaining steps are the same as those in Example 1.

[0062] Table 1

[0063]

[0064]

[0065] Example 20

[0066] This embodiment relates to a cooking appliance with good fume catalytic effect, including a cooking cavity, a hot air component and a catalytic module. The hot air component includes a hot air fan and a heating element. The catalytic module is arranged adjacent to the heating element. The hot air component generates hot air and inputs it into the cooking cavity to cook the food materials. The catalytic module is used for catalytic decomposition of the fume close to and / or flowing through it. Wherein, the preparation method of the catalytic module includes the following steps:

[0067] (1) Mix pseudo-boehmite and ZSM-5 with a weight ratio of 1:9. The average particle size of ZSM-5 is 50 nm, and the specific surface area > 350 m 2 / g. Add it to 20% nitric acid and mix to form a slurry. Bake it in a high-temperature furnace at 400 °C for 4 h, then immerse it in a 2 mol / L ammonium nitrate solution, wash and dry it, and calcine it at 700 °C for 3 h. After cooling, grind it to obtain a γ-alumina / ZSM-5 composite;

[0068] (2) According to the weight conversion of 30% cerium oxide, 0.5% lanthanum oxide and 0.5% iron oxide into the weights of corresponding cerium nitrate, lanthanum nitrate, iron nitrate and calcium nitrate, weigh and dissolve the above cerium nitrate, lanthanum nitrate, iron nitrate and calcium nitrate in a 0.5% nitric acid solution. Immerse the γ-alumina / ZSM-5 composite in this solution, dry it at 200 °C after immersion, repeat the immersion 3 times, and then calcine it at 700 °C for 2 h to obtain an intermediate;

[0069] According to the weight conversion of 0.1% platinum and 1% palladium into the weights of corresponding platinum nitrate and palladium nitrate, weigh and dissolve the above platinum nitrate and palladium nitrate in a 0.5% nitric acid solution. Immerse the intermediate in this solution, and calcine it at 700 °C for 2 h after immersion to obtain the catalyst;

[0070] (3) Attach the catalyst to the surface of a porous material to obtain the catalytic module. The porous material is a honeycomb structure made of an iron-chromium-aluminum material plate.

[0071] Example 21

[0072] This embodiment relates to a cooking appliance with good fume catalytic effect, including a cooking cavity, a hot air component and a catalytic module. The hot air component includes a hot air fan and a heating element. The catalytic module is arranged adjacent to the heating element. The hot air component generates hot air and inputs it into the cooking cavity to cook the food materials. The catalytic module is used for catalytic decomposition of the fume close to and / or flowing through it. Wherein, the preparation method of the catalytic module includes the following steps:

[0073] (1) Mix pseudo-boehmite and ZSM-5 with a weight ratio of 1:9. The average particle size of ZSM-5 is 100 nm, and the specific surface area > 350 m 2Per g, add it to 10% nitric acid and mix to form a slurry. Bake it in a high-temperature furnace at 500 °C for 3 h. Then immerse it in a 1 mol / L ammonium nitrate solution, wash and dry it, and calcine it at 400 °C for 8 h. After cooling, grind it to obtain the γ-alumina / ZSM-5 composite;

[0074] (2) According to the weight conversion of 10% cerium oxide, 5% lanthanum oxide, 5% iron oxide, and 5% calcium oxide to the corresponding weights of cerium nitrate, lanthanum nitrate, iron nitrate, and calcium nitrate, weigh the above-mentioned cerium nitrate, lanthanum nitrate, iron nitrate, and calcium nitrate and dissolve them in a 0.5% nitric acid solution. Immerse the γ-alumina / ZSM-5 composite in this solution, dry it at 150 °C after immersion, repeat the immersion 5 times, and then calcine it at 500 °C for 4 h to obtain an intermediate;

[0075] According to the weight conversion of 1.5% platinum and 0.05% palladium to the corresponding weights of platinum nitrate and palladium nitrate, weigh the above-mentioned platinum nitrate and palladium nitrate and dissolve them in a 0.5% nitric acid solution. Immerse the intermediate in this solution, and calcine it at 500 °C for 4 h after immersion to obtain the catalyst;

[0076] (3) Attach the catalyst to the surface of the porous material to obtain a catalytic module. The porous material is a honeycomb structure made of an iron-chromium-aluminum material plate.

[0077] Test Example

[0078] Average pore size and specific surface area:

[0079] Use a BET-BJH analyzer for specific surface area and pore size, and use the nitrogen adsorption-desorption method to test the average pore size and specific surface area of the γ-alumina / ZSM-5 composite prepared in the above examples and comparative examples. The results are shown in Table 2 below.

[0080] Test on the catalytic oxidation effect of cooking fume VOC:

[0081] After grinding the catalyst prepared in step (2) of the above examples and comparative examples, coat it on a cordierite honeycomb carrier with a diameter of 200 mesh / inch, a diameter of 4 cm, and a thickness of 3 cm, and sinter it at high temperature to obtain a porous honeycomb catalytic module.

[0082] Fix the catalytic module near the circulation fan and heating tube of the air fryer, and then raise the temperature to conduct catalytic purification test verification: Test the oil fume VOC generated by cooking 300g of chicken wings in the air fryer. Set the air temperature of the air fryer at 220°C, and the rotational speeds of the centrifugal fan are 3200 rpm, 2500 rpm, and 1800 rpm respectively. Seal the entire air fryer with a VOC gas collection bag. The oil fume VOC generated during the cooking process will be collected by the collection bag, and the total VOC content in the collection bag will be tested using a gas chromatograph. Test the VOC emissions without and with the catalyst respectively, and calculate the VOC removal rate. VOC removal rate = (VOC emissions without catalyst - VOC emissions with catalyst) / VOC emissions without catalyst * 100%, and the results are shown in Table 2 below.

[0083] Effect test of the catalyst on cracking oil scale:

[0084] Take the oil scale in the range hood and add the catalyst, and mix them according to the mass ratio of oil scale: catalyst = 20:1. Heat in a three-necked flask, control the heating temperature at 300°C, and heat for 20 minutes. Use the same mass of oil scale without adding the catalyst and conduct a control test under the same conditions, and calculate the oil scale cracking rate. The remaining oil scale m1 in the flask without adding the catalyst and the remaining oil scale mass m2 with the catalyst added. Oil scale cracking rate = (m1 - m2) / m1 * 100%, and the results are shown in Table 2 below.

[0085] Table 2

[0086]

[0087]

[0088] According to Table 1-2, it can be seen that the catalyst prepared in this application can not only catalytically oxidize the VOC in the oil fume, but also crack the macromolecular oil scale, thereby improving the purification effect of the oil fume and extending the service life of the catalyst.

[0089] In Examples 1-6, the weight ratio of pseudo-boehmite to ZSM-5 is different, which mainly affects the pore size and specific surface area of the γ-alumina / ZSM-5 composite, and further affects the catalytic effect on VOC and the cracking rate of oil scale. According to the comparison between Comparative Examples 1, 2 and Example 1, when using a single ZSM-5 as the catalyst support, the oil scale cracking rate remains roughly unchanged. However, due to the small pore size of ZSM-5, the amount of oil fume gas entering the catalyst support decreases, so the VOC removal rate decreases, and the higher the wind speed, the more obvious the decrease; when using a single γ-alumina as the catalyst support, the VOC removal rate slightly increases at low wind speeds and significantly decreases at high wind speeds, and the decreasing trend of the oil scale cracking rate is more obvious. According to the comparison between Comparative Example 3 and Example 1, as the proportion of pseudo-boehmite increases, the pore size of the catalyst support increases and the specific surface area decreases, and the residence time of oil fume in the catalyst support shortens. Therefore, the VOC removal rate decreases at high wind speeds, and the oil scale cracking rate decreases more.

[0090] According to the comparison between Examples 7-9 and Example 4, it can be seen that the content of cerium oxide affects the VOC removal rate and the oil scale cracking rate. Too high or too low cerium oxide will cause both the VOC removal rate and the oil scale cracking rate to decrease; according to the comparison between Examples 10-12 and Example 4, as the content of lanthanum oxide decreases, the catalytic effect of the catalyst decreases and the oil scale cracking rate decreases; as the content of lanthanum oxide increases, the VOC removal rate and the oil scale cracking efficiency basically no longer increase.

[0091] According to the comparison between Example 13 and Example 4, when the content of iron oxide decreases, the difference in the VOC removal rate is not significant, but the oil scale cracking rate will decrease; according to the comparison between Examples 14, 15 and Example 4, as the content of calcium oxide decreases, the VOC removal rate increases, but the decreasing trend of the oil scale cracking rate is more obvious. Therefore, the calcium oxide content should not exceed 5%.

[0092] According to the comparison between Examples 16, 17 and Example 4, as the platinum content increases, the VOC removal rate increases, but the oil scale cracking rate decreases; as the platinum content decreases, both the VOC removal rate and the oil scale cracking rate decrease. According to the comparison between Examples 18, 19 and Example 4, as the palladium content decreases, the VOC removal rate decreases, and the decreasing trend of the oil scale cracking rate is more obvious. When palladium is not added, the VOC removal rate increases at low wind speeds and decreases at high wind speeds, and the oil scale cracking rate also decreases.

[0093] As described above, only the embodiments of the present application are given. The protection scope of the present application is not limited by these specific embodiments, but is determined by the claims of the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the technical idea and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A cooking appliance with good catalytic effect on lampblack, comprising a cooking cavity, a hot air assembly and a catalytic module. The hot air assembly includes a hot air fan and a heating element. The catalytic module is arranged adjacent to the heating element. The hot air assembly generates hot air and inputs it into the cooking cavity to cook food materials. The catalytic module is used for catalytic decomposition of lampblack close to and / or flowing through it. It is characterized in that The catalytic module includes a porous material and a catalyst attached to the surface of the porous material. The catalyst includes a catalyst carrier and a combustion catalyst attached to the surface of the catalyst carrier. The catalyst carrier is a γ-alumina / ZSM-5 composite, and the γ-alumina / ZSM-5 composite is prepared from pseudo-boehmite and ZSM-5 with a weight ratio of 1-7:3-9.

2. The cooking appliance with good fume catalysis effect according to claim 1, wherein, The γ-alumina / ZSM-5 composite is prepared from pseudo-boehmite and ZSM-5 with a weight ratio of 3-6:4-7.

3. The cooking appliance with good fume catalysis effect according to claim 1, characterized in that, The specific surface area of the γ-alumina / ZSM-5 composite is 170-330 m 2 / g, and the pore diameter is 1.1-16 nm.

4. The cooking appliance with good fume catalytic effect according to claim 1, characterized in that The combustion catalyst is any one or a combination of noble metal catalysts, non-noble metal oxide catalysts, and transition metal oxide catalysts.

5. The cooking appliance with good fume catalysis effect according to claim 4, wherein The combustion catalyst is a noble metal catalyst and a non-noble metal oxide catalyst. The non-noble metal oxide catalyst is attached to the surface of the catalyst carrier, and at least part of the noble metal catalyst is dispersedly attached to the surface of the non-noble metal oxide catalyst.

6. The cooking appliance with good fume catalytic effect according to claim 5, characterized in that The noble metal catalyst includes platinum and palladium; The weight percentage of platinum in the γ-alumina / ZSM-5 composite is 0.1%-1.5%; The weight percentage of palladium in the γ-alumina / ZSM-5 composite is 0.05%-1%.

7. The cooking appliance with good fume catalytic effect according to claim 5, characterized in that, The non-noble metal oxide catalyst includes cerium oxide, lanthanum oxide, and iron oxide; The weight percentage of cerium oxide in the γ-alumina / ZSM-5 composite is 10%-30%; The weight percentage of lanthanum oxide in the γ-alumina / ZSM-5 composite is 0.5%-5%; The weight percentage of iron oxide in the γ-alumina / ZSM-5 composite is 0.5%-5%.

8. The cooking appliance with good fume catalytic effect according to claim 7, characterized in that, The non-noble metal oxide catalyst further includes calcium oxide, and the weight percentage of calcium oxide in the γ-alumina / ZSM-5 composite is 0.1%-5%.

9. The cooking appliance with good fume catalytic effect according to any one of claims 1-8, characterized in that, The preparation method of the catalyst includes the following steps: (1) Mix pseudo-boehmite and ZSM-5, add them to an acidic solvent to form a slurry, bake it, then immerse it in an ammonium nitrate solution, wash, dry, and calcine to obtain the γ-alumina / ZSM-5 composite; (2) Immerse the γ-alumina / ZSM-5 composite in the salt solution of the combustion catalyst, dry and calcine to obtain the catalyst.

10. The cooking appliance with good fume catalytic effect according to claim 9, characterized in that, In step (2), the combustion catalyst includes a noble metal catalyst and a non-noble metal oxide catalyst; Immerse the γ-alumina / ZSM-5 composite in the salt solution of a non-noble metal, dry and calcine to obtain an intermediate, then immerse the intermediate in the salt solution of a noble metal, and calcine to obtain the catalyst.

Images