Carbon monoxide catalytic combustion catalyst and method for preparing the same
By utilizing waste copper-based methanol synthesis catalysts to prepare carbon monoxide catalytic combustion catalysts, the problems of complex preparation and high cost in existing technologies have been solved, achieving low-cost and high-efficiency CO catalytic oxidation and purification effects.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIJING YUZHI ENVIRONMENTAL PROTECTION TECH CO LTD
- Filing Date
- 2024-08-13
- Publication Date
- 2026-06-19
AI Technical Summary
The existing methods for preparing catalysts for CO catalytic oxidation purification are complex and costly, which limits their widespread application.
A carbon monoxide catalytic combustion catalyst was prepared by using waste copper-based methanol synthesis catalyst as raw material through crushing, roasting, water washing and filtration, kneading and molding. Cu, ZnO and Al2O3 in the waste catalyst were used as active ingredients and carriers, and aluminate coupling agent and gibbsite were added to improve the catalyst performance.
It reduced the preparation cost of the catalyst, improved the service life and catalytic performance of the catalyst, increased the CO conversion rate, and enhanced the water resistance of the catalyst.
Smart Images
Figure CN119236946B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the fields of air pollution control and solid waste pollution disposal in advanced environmental protection industries, and particularly to a carbon monoxide catalytic combustion catalyst and its preparation method. Background Technology
[0002] Carbon monoxide is an air pollutant, primarily originating from metallurgical processes such as coking and iron smelting, and chemical processes such as ammonia and methanol synthesis. Because carbon monoxide has a 230-270 times greater affinity for hemoglobin than oxygen, and the dissociation rate of carboxyhemoglobin (formed from carbon monoxide) is 3600 times slower than that of oxyhemoglobin, inhaling carbon monoxide can cause hypoxic poisoning in animals. Prolonged exposure to low concentrations of carbon monoxide can lead to chronic poisoning, affecting the cardiovascular and nervous systems.
[0003] In the coking industry, the carbon monoxide content in the vent gas commonly used for dry quenching is about 2-5%. Controlling the amount of air entering the dry quenching furnace is an important means to reduce the amount of carbon monoxide generated in the dry quenching flue gas, but at present, its reduction effect is limited.
[0004] The main CO purification technologies include physical methods (low-temperature separation, adsorption, etc.) and chemical methods (solution absorption, combustion, and catalytic oxidation, etc.). Among these technologies, catalytic oxidation is favored due to its high purification efficiency, ease of operation, and ability to recover heat energy; the catalyst is the key component of this technology.
[0005] In the process of realizing this invention, the applicant found that the catalyst preparation methods of existing CO catalytic oxidation purification methods are complex and costly, which greatly limits the promotion and application of CO catalytic oxidation purification methods. Summary of the Invention
[0006] I. Technical problems to be solved
[0007] The present invention aims to at least partially solve one of the above-mentioned technical problems.
[0008] II. Technical Solution
[0009] The first aspect of this invention provides a method for preparing a carbon monoxide catalytic combustion catalyst. The method for preparing the carbon monoxide catalytic combustion catalyst includes:
[0010] Step A: The waste copper-based methanol synthesis catalyst is crushed to obtain the first powder;
[0011] Step B: Calcination of the first powder;
[0012] Step C: Wash and filter the first powder after calcination to obtain filter cake material;
[0013] Step D: After drying the filter cake material, crush it to obtain the second powder;
[0014] Step E: Add the second powder to the molding aid and knead to obtain a semi-finished product.
[0015] Step F involves shaping the semi-finished material and then drying and calcining it to obtain a carbon monoxide catalytic combustion catalyst.
[0016] In some embodiments of the present invention, in step A, a waste copper-based methanol synthesis catalyst is used as a reference for unit mass. The waste copper-based methanol synthesis catalyst contains: CuO, with a weight percentage content of not less than 50%; Al2O3, with a weight percentage content of not less than 10%; and ZnO, with a weight percentage content of not less than 10%.
[0017] In some embodiments of the present invention, in step B, the first powder is calcined at a temperature between 300 and 450°C for a time between 3 and 5 hours, in an oxygen-containing atmosphere with an oxygen content of ≥10%.
[0018] In some embodiments of the present invention, in step A, the waste copper-based methanol synthesis catalyst is crushed until the particle size is less than 50 μm; in step C, the first powder after calcination is repeatedly washed and filtered with water until the following weight percentage content of Na element is less than 0.08%; the weight percentage content of Cl element is less than 0.05%; and the weight percentage content of S element is less than 0.05%.
[0019] In some embodiments of the present invention, step E includes: sub-step E1, mixing the second powder with a surface activator, wherein the surface activator includes: an aluminate coupling agent and petroleum ether; sub-step E3, adding a molding aid and continuing to mix.
[0020] In some embodiments of the present invention, step E1 includes: dissolving and dispersing the aluminate coupling agent in petroleum ether to obtain an aluminate coupling agent dispersion; adding the second powder and the aluminate coupling agent dispersion to a kneader for mixing; or adding the second powder and the aluminate coupling agent to a kneader for solid-solid mixing; adding petroleum ether to the kneader and continuing to mix.
[0021] In some embodiments of the present invention, in the surfactant of sub-step E1, the aluminate coupling agent is isopropyl distearate aluminate, and its weight percentage content is between 0.1% and 2%, preferably between 0.3% and 1%; the mass of petroleum ether is 5 to 20 times the mass of the aluminate coupling agent, preferably 8 to 15 times.
[0022] In some embodiments of the present invention, the sub-step between E1 and E3 further includes: sub-step E2, adding a bridging agent and continuing to knead, wherein the bridging agent is gibbsite material, and the weight percentage content of gibbsite is between 2% and 10%, preferably between 3% and 6%.
[0023] In some embodiments of the present invention, in sub-step E3, the molding aid includes: PEO and ammonium bicarbonate, wherein the weight percentage content of PEO is between 0.5% and 3%, preferably between 1% and 3%; and the weight percentage of ammonium bicarbonate is between 0.5% and 3%, preferably between 0.5% and 2%.
[0024] In some embodiments of the present invention, the molding aid further includes one or more of the following materials: stearic acid, CMC-NH4, monoethanolamine, and ammonia.
[0025] In some embodiments of the present invention, step D includes: sub-step D1, drying the filter cake material at a temperature between 100°C and 300°C; and sub-step D2, crushing the dried filter cake material to a particle size of less than 50 μm.
[0026] In some embodiments of the present invention, step F includes: sub-step F1, molding the semi-finished material, wherein the molding process is one of the following: extrusion molding, ball rolling molding, honeycomb extrusion molding, coating molding; sub-step F2, drying the molded material to make the moisture content less than 5%; and sub-step F3, calcining the dried material at a calcination temperature of 300-500°C.
[0027] A second aspect of the present invention provides a carbon monoxide catalytic combustion catalyst. This carbon monoxide catalytic combustion catalyst is prepared using the method described above.
[0028] III. Beneficial Effects
[0029] As can be seen from the above technical solution, the present invention has at least one of the following beneficial effects compared to the prior art:
[0030] 1. This invention turns waste into treasure by using waste methanol synthesis catalyst to obtain carbon monoxide catalytic combustion catalyst, which has good prospects for promotion and application.
[0031] In this invention, the large amount of copper and zinc elements in the waste methanol synthesis catalyst are fully utilized to isolate copper and create a large number of active sites to compensate for the lack of water resistance of carbon monoxide catalytic combustion catalyst.
[0032] In this invention, zinc oxide naturally present in the waste methanol synthesis catalyst, along with the -Cu-O-Zn-O-Cu- structure, is used to isolate copper elements, effectively dispersing copper oxide and improving catalytic performance.
[0033] 2. In this invention, the calcination temperature is 300–450°C, preferably 380–420°C. The calcination temperature should not be too low or too high. If the temperature is too low, Cu cannot be oxidized to CuO; if the temperature is too high, CuO will decompose into Cu2O. Similarly, the active components will migrate and aggregate, causing their grains to grow and reducing catalytic activity. The calcination time should also not be too long, as this will also cause the active component grains to grow. The calcination time is 1–6 hours, preferably 1–3 hours.
[0034] 3. In this invention, the applicant has prepared a technical solution involving the crushing, calcination, and repeated water washing and filtration of a waste copper-based methanol synthesis catalyst, specifically embodied in steps A to C. Through the combined effect of the above steps, the weight percentage content of Na element in the waste copper-based methanol synthesis catalyst is successfully reduced to below 0.1%, thereby improving the service life of the prepared carbon monoxide catalytic combustion catalyst and enhancing the catalytic effect.
[0035] 4. In this invention, alumina that has been passivated by calcination is reactivated by an aluminate coupling agent, making it easier to connect with other substances and to connect with itself (alumina to alumina), thus restoring its binder function. Therefore, the addition of the aluminate coupling agent can fully utilize the alumina in the waste methanol synthesis catalyst, increasing the strength after molding. Simultaneously, the coupling agent can also act as a bridge between inorganic and organic materials; in the presence of other organic compounds, the coupling agent also plays a certain dispersing role. Petroleum ether is an auxiliary agent for the aluminate coupling agent, which helps in its dispersion.
[0036] 5. In this invention, the addition of gibbsite can effectively bridge the alumina modified by the aluminate coupling agent during the calcination process. After calcination, gibbsite will be transformed into alumina, forming a bridge connecting alumina and alumina, and forming channels and cavities. Attached Figure Description
[0037] Figure 1 This is a flowchart of the preparation method of carbon dioxide catalytic combustion catalyst in Embodiment 1 of the present invention.
[0038] Figure 2 for Figure 1 The diagram shows a mixing process in step E of the carbon monoxide catalytic combustion catalyst preparation method.
[0039] Figure 3 This is the molecular formula for modifying the surface of alumina using an aluminate coupling agent in the embodiments of the present invention.
[0040] Figure 4 This is the molecular formula of gibbsite.
[0041] Figure 5 To investigate the bridging mechanism of alumina obtained by calcining gibbsite. Detailed Implementation
[0042] This invention addresses the problems of excessive carbon monoxide emissions and short catalyst life in existing technologies, such as coke oven flue gas and dry quenching exhaust gas, by providing a low-cost, low-pollution carbon monoxide catalytic combustion catalyst.
[0043] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.
[0044] The first aspect of this invention provides a method for preparing a carbon monoxide catalytic combustion catalyst. Figure 1 This is a flowchart illustrating the preparation method of the carbon monoxide catalytic combustion catalyst according to an embodiment of the present invention. Figure 1 As shown, the preparation method of the carbon monoxide catalytic combustion catalyst in this embodiment includes:
[0045] Step A: The waste copper-based methanol synthesis catalyst is crushed to obtain the first powder;
[0046] Step B: Calcination of the first powder;
[0047] Step C: The first powder after calcination is repeatedly washed and filtered with water to obtain filter cake material;
[0048] Step D: After drying the filter cake material, crush it to obtain the second powder;
[0049] Step E: Add the second powder to the molding aid and knead to obtain a semi-finished product.
[0050] Step F involves shaping the semi-finished material and then drying and calcining it to obtain a carbon monoxide catalytic combustion catalyst.
[0051] In this embodiment, waste is turned into treasure, and carbon monoxide catalytic combustion catalyst is obtained from waste methanol synthesis catalyst, which has good prospects for promotion and application.
[0052] The following sections provide a detailed description of each step in the preparation method of the carbon monoxide catalytic combustion catalyst in this embodiment.
[0053] In existing technologies, there are methods for preparing mercury removal agents using waste copper-based methanol synthesis catalysts. However, the applicant conducted carbon monoxide catalytic combustion experiments using the product prepared by this method, but the catalytic effect and service life were not ideal. Through theoretical research and repeated experiments, the applicant discovered that the sodium element has a negative effect.
[0054] Specifically, the treated product contains trace amounts of sodium (Na). Inductively coupled plasma optical emission spectrometry (ICP-OES) analysis, using the waste copper-based methanol synthesis catalyst as a reference, showed that the Na content by weight was between 0.3% and 0.5%. As a carbon monoxide catalytic combustion catalyst, a Na content exceeding 0.1% by weight severely impacts the catalyst's lifespan. This is because the Na in the catalyst mainly exists as soluble salts such as Na₂SO₄ and NaNO₃. During use, water vapor and heat promote the migration of these soluble salts to the catalyst surface, thus covering the active sites and leading to catalyst deactivation.
[0055] Based on the above analysis, the applicant has developed a technical solution involving the crushing, calcination, and repeated water washing and filtration of waste copper-based methanol synthesis catalysts, specifically embodied in steps A to C. Through the combined effect of the above steps, the weight percentage content of Na in the waste copper-based methanol synthesis catalyst has been successfully reduced to below 0.1%, thereby improving the service life of the prepared carbon monoxide catalytic combustion catalyst and enhancing its catalytic effect.
[0056] In this invention, the applicant conducted experiments on spent copper-based methanol synthesis catalysts from various sources and found that any spent copper-based methanol synthesis catalyst meeting the following conditions can achieve this invention: CuO, with a weight percentage content of not less than 50%; Al2O3, with a weight percentage content of not less than 10%; ZnO, with a weight percentage content of not less than 10%. It should be noted again that the weight percentage content in this invention is based on the spent copper-based methanol synthesis catalyst as a unit mass reference, and will not be repeated hereafter.
[0057] To ensure the rigor of the experimental results, after verifying various sources of spent copper-based methanol synthesis catalysts, subsequent experiments used the same spent copper-based methanol synthesis catalyst. The weight percentage content of this spent copper-based methanol synthesis catalyst is as follows: CuO, 62.63%; ZnO, 21.53%; Al₂O₃, 12.35%; Fe₂O₃, 1.84%; SiO₂, 0.80%; Na₂O, 0.57%; SO₂, 0.28%.
[0058] In step A of this embodiment, the waste methanol synthesis catalyst is crushed to a particle size of less than 50 μm to obtain the first powder.
[0059] In existing technologies, most methanol synthesis catalysts are formed into cylindrical pieces, with a diameter and height of 4-5 mm, exhibiting high strength and large particle size. Crushing the spent methanol synthesis catalyst facilitates subsequent roasting and washing. Without crushing, the catalyst interior may not come into contact with oxygen during roasting, leading to incomplete roasting; and during washing, water cannot effectively penetrate the catalyst interior, failing to dissolve impurities and reduce the sodium content, thus affecting the washing effect.
[0060] In step B of this embodiment, the first powder is calcined at 300–450°C for 3–5 hours and then cooled to room temperature. The atmosphere is an oxygen-containing atmosphere with an oxygen content ≥10%, preferably ≥15%.
[0061] As mentioned above, the spent copper-based methanol synthesis catalyst contains a relatively large amount of Cu, ZnO, and Al2O3, and small amounts of CuO, CuS, Cu2S, ZnS, and Fe. 3+ It contains substances such as Cl-, as well as trace amounts of Na.
[0062] The purpose of roasting in this step is:
[0063] ① Cu must be converted into CuO, which then possesses the catalytic combustion activity for carbon monoxide. The calcination temperature is 300–450℃, preferably 380–420℃. The calcination temperature should not be too low or too high. If the temperature is too low, Cu cannot be oxidized to CuO; if the temperature is too high, CuO will decompose into Cu2O. Similarly, the active components will migrate and aggregate, causing their grains to grow and reducing catalytic activity. The calcination time should also not be too long, as this will also cause the active component grains to grow. The calcination time is 1–6 hours, preferably 1–3 hours.
[0064] ② Convert sulfur in sulfides into SO2 or SO4. 2- SO2 escapes during the roasting process, SO4... 2- Subsequent washing removes the residue.
[0065] In step C of this embodiment, the first powder after calcination is repeatedly washed and filtered with water until the following weight percentages of Na are less than 0.08%; Cl is less than 0.05%; and S is less than 0.05%. It should be noted that the weight percentages of the above elements are measured by ICP method, with the weight percentages using waste copper-based methanol synthesis catalyst as a reference per unit mass.
[0066] It should be noted that in the copper-based methanol synthesis catalyst, soluble salts, such as Na... + Cl - SO4 2-These impurities, such as sodium, can reduce catalyst lifespan and even decrease activity. This invention effectively removes impurities like sodium (Na₂O) present in the catalyst due to contamination or raw material residues through crushing, roasting, and water washing. + Cl - SO4 2- This process avoids reducing the catalyst's lifespan and activity due to the presence of these substances. Simultaneously, calcination converts Cu to CuO, enhancing catalytic activity.
[0067] Step D in this embodiment includes two steps: a drying step and a crushing step.
[0068] For the drying step, after washing and filtration, the filter cake is dried at a temperature of 100–300°C. Considering energy consumption, a temperature of 150–250°C is preferred to facilitate subsequent crushing and prevent premature hydrolysis of the aluminate coupling agent due to insufficient dispersion. If the water content is too high, the material cannot be crushed to 15 μm. Furthermore, if an aluminate coupling agent is added subsequently, the water content should be controlled below 1%, preferably below 0.5%.
[0069] As for the crushing step, the material will inevitably clump together after washing and drying, and must be crushed. Otherwise, the subsequent mixing of molding additives will result in uneven mixing of the additives. In addition, if the material particles are too large, subsequent material forming operations such as extrusion into strips and honeycomb molding will not be possible.
[0070] In the prior art, there are carbon monoxide removal catalysts and their preparation methods. These catalysts include a support and an active component loaded on the support, with the support content being 30-50% by weight. The support is a composite of titanium dioxide and activated alumina; however, the addition of titanium dioxide increases the cost and also reduces the activity of Cu in the catalyst.
[0071] To address the problems existing in the prior art, this invention proposes using the alumina and zinc oxide inherent in the waste copper-based methanol synthesis catalyst as a carrier, and utilizing modified alumina as the main binder for molding. Details are as follows.
[0072] Figure 2 for Figure 1 The diagram shows a mixing process in step E of the carbon monoxide catalytic combustion catalyst preparation method. Figure 2 As shown, in this embodiment, step E includes:
[0073] Sub-step E1 involves mixing the second powder with a surface activator, wherein the surface activator includes: an aluminate coupling agent and petroleum ether.
[0074] Sub-step E2: Add a bridging agent and continue kneading, wherein the bridging agent is gibbsite material;
[0075] In sub-step E3, add molding aids and continue kneading.
[0076] It should be noted that the material addition ratios mentioned in the following steps are all excluding water.
[0077] In this embodiment, a surfactant including an aluminate coupling agent and petroleum ether is used. For example... Figure 2 As shown, sub-step E1 further includes:
[0078] ① Dissolve and disperse the aluminate coupling agent in petroleum ether to obtain an aluminate coupling agent dispersion for later use; the aluminate addition ratio is 0.1-2%, preferably 0.3-1%; the petroleum ether is 5-20 times the amount of aluminate, preferably 8-15 times;
[0079] ② Add the second powder after the waste methanol catalyst treatment and the above-mentioned aluminate coupling agent dispersion to the kneader and knead for 20-40 minutes.
[0080] The following provides a further detailed explanation of the function of each component in the surfactants added in this sub-step.
[0081] 1. Aluminate coupling agent
[0082] Aluminate coupling agents are surfactants that help bind alumina and added gibbsite in waste catalysts to other materials, which are then converted into alumina after calcination. Since waste methanol synthesis catalysts contain about 10% (5-15%) alumina, adding aluminate coupling agents can modify the alumina surface, allowing hydroxyl groups (-OH) to be re-grafted onto the alumina surface. Figure 3 This refers to the molecular formula of the alumina surface modified using an aluminate coupling agent in the embodiments of the present invention. For example... Figure 3 As shown, aluminate coupling agents reactivate alumina that has been passivated by calcination, making it easier for it to connect with other substances and to connect with itself (alumina to alumina), thus restoring its binder function. Therefore, adding aluminate coupling agents can fully utilize the alumina in the waste methanol synthesis catalyst, increasing the strength after molding. Simultaneously, the coupling agent can also act as a bridge between inorganic and organic compounds, and in the presence of other organic compounds, it also plays a certain dispersing role. However, the amount of aluminate coupling agent added should not be excessive, as too much will severely cover the active sites. Aluminate coupling agents are available in several models depending on the organic groups, but the model specifications published by different manufacturers are not standardized.
[0083] In this embodiment, the coupling agent used is isopropyl distearate aluminate, and it has been confirmed that it can achieve the corresponding function. Based on the common understanding of those skilled in the art, other types of coupling agents should also be able to achieve similar functions.
[0084] 2. Petroleum ether
[0085] Petroleum ether is an additive for aluminate coupling agents, aiding in their dispersion. Because aluminate coupling agents hydrolyze in water, if they are hydrolyzed before effective dispersion, they cannot function properly. Therefore, the aluminate coupling agent must first be dispersed on the surface of the alumina to be modified before hydrolysis to fully exert its effect. As mentioned above, aluminate coupling agents hydrolyze in water; effective dispersion requires either the addition of a solvent to dissolve them or heating (above 80°C) to melt them. If the aluminate coupling agent is dispersed by heating and melting, petroleum ether is not necessary. Added petroleum ether volatilizes during the drying process and creates pores.
[0086] Furthermore, it should be noted that the above is only one implementation of the present invention. In another implementation, the following methods may also be used: The second powder and the aluminate coupling agent are added to a kneader for solid-solid mixing; petroleum ether is added to the kneader, and kneading continues. Alternatively: The aluminate coupling agent is first dissolved and dispersed in petroleum ether to prepare an aluminate coupling agent petroleum ether dispersion for later use; the second powder from step D is placed in the kneader and stirring is started; then the aluminate coupling agent petroleum ether dispersion is slowly poured into the kneader, and kneaded for 20-40 minutes. Both methods can achieve similar results.
[0087] In this embodiment, as Figure 2 As shown, in sub-step E2, gibbsite is added to a kneader and kneaded for 20-30 minutes. The mass ratio of gibbsite added is 2-10%, preferably 3-6%.
[0088] In the existing technology, there is no technical solution that uses aluminate coupling agents to modify alumina and simultaneously applies gibbsite bridging. Figure 4 This is the molecular formula of gibbsite. Figure 5 To utilize the bridging mechanism of alumina obtained from calcined gibbsite. For example... Figure 4 and Figure 5 As shown, the addition of gibbsite can effectively bridge the alumina modified by the aluminate coupling agent during the calcination process. After calcination, gibbsite will be transformed into alumina, forming a bridge connecting alumina and alumina, and forming channels and cavities.
[0089] In this embodiment, in sub-step E3, the molding aids include: PEO (polyethylene oxide) and ammonium bicarbonate. Sub-step E3 further includes:
[0090] ① Add PEO and knead for 20-30 minutes. The proportion of PEO added is 0.5-3%, preferably 1-3%.
[0091] ② Add 20g of water, knead for 10 minutes, then add another 20g of water and knead for 10-20 minutes to hydrolyze the aluminate coupling agent;
[0092] ③ Add ammonium bicarbonate and knead for 10-20 minutes. The proportion of ammonium bicarbonate added is 0.5-3%, preferably 0.5-2%.
[0093] ④ Add the remaining water in small amounts multiple times. To meet the requirements for extrusion molding, the amount added can be increased or decreased appropriately according to the state.
[0094] Those skilled in the art should understand that the above are merely molding aids required for extrusion molding. In other embodiments of the present invention, if other molding methods are required, appropriate molding aids can be selected, such as one or more of stearic acid, ammonium bicarbonate, PEO, CMC-NH4 (carboxymethyl cellulose ammonium), monoethanolamine, and ammonia. The molding aids added will vary depending on the molding process.
[0095] The following provides a more detailed explanation of the functions of each component of the molding aids added in this step.
[0096] 1. Stearic acid
[0097] Stearic acid mainly serves as a lubricant during the extrusion process;
[0098] 2. Ammonium bicarbonate
[0099] Ammonium bicarbonate is a pH adjuster that can neutralize weak acids produced by the hydrolysis of aluminate coupling agents. It is also a pore-forming agent and can be completely decomposed at temperatures above 60°C.
[0100] 3. PEO and CMC-NH4
[0101] PEO, CMC-NH4, and monoethanolamine mainly act as binders to facilitate extrusion molding. They are almost completely burned off during calcination, while simultaneously creating pores.
[0102] 4. Ammonia
[0103] Ammonia water mainly serves to assist in the dissolution of CMC-NH4.
[0104] In step F of this embodiment, the semi-finished material is shaped and then dried and calcined to obtain a carbon monoxide catalytic combustion catalyst. Step F further includes:
[0105] Sub-step F1 involves shaping the semi-finished material using one of the following processes: extrusion molding, ball rolling molding, honeycomb extrusion molding, or coating molding.
[0106] Sub-step F2 involves drying the shaped material to reduce the moisture content to below 5%, preferably to below 3% (the moisture content can be controlled to below 5% for extrusion molding).
[0107] Sub-step F3 involves roasting the dried material at a temperature of 300–500°C, preferably 350–400°C.
[0108] Those skilled in the art should understand that various molding processes also draw on past industry experience in part, such as extrusion molding, ball forming, and honeycomb extrusion molding, but there will be variations depending on the materials and different operating conditions.
[0109] It should also be noted that some existing carbon monoxide removal catalysts use titanium dioxide as the main component, which increases costs and reduces the activity of Cu in the catalyst. Some existing carbon monoxide catalysts also add silica. However, the applicant has found that adding silica does not improve water resistance; on the contrary, it dilutes the active components, thus reducing the overall performance of the catalyst.
[0110] Unlike the prior art described above, the present invention also has the following characteristics:
[0111] ① No titanium dioxide is introduced
[0112] In this invention, titanium dioxide is not introduced, thus avoiding any impact on the activity of copper due to its introduction. This invention primarily utilizes the alumina and zinc oxide inherent in the waste methanol synthesis catalyst as a carrier, and uses the alumina itself as the main binder for molding.
[0113] ② No silicon dioxide is introduced.
[0114] In this invention, no substances such as silicon dioxide that do not contribute to catalytic activity are added. Instead, the large amount of copper and zinc in the waste methanol synthesis catalyst is fully utilized to isolate copper and create a large number of active sites to compensate for the lack of water resistance of carbon monoxide catalytic combustion catalyst.
[0115] ③ Utilize the zinc oxide naturally present in the waste methanol synthesis catalyst to isolate copper elements.
[0116] In addition, by utilizing the zinc oxide naturally present in the waste methanol synthesis catalyst and the -Cu-O-Zn-O-Cu- structure, the zinc element isolates the copper element, effectively dispersing the copper oxide and improving the catalytic performance.
[0117] ④ Utilize modifiers to enhance the strength and effectiveness of carbon monoxide catalytic combustion catalysts.
[0118] In this invention, a small amount of aluminate coupling agent is added to modify the alumina in the waste methanol synthesis catalyst, grafting hydroxyl groups (-OH) onto its surface. Then, gibbsite is added to bridge the alumina, which can greatly improve the catalyst strength (extrusion molding, aluminate coupling agent addition of 0.5%, gibbsite addition of 5%, radial crushing resistance of about 110 N / cm).
[0119] A second aspect of this invention provides a carbon monoxide catalytic combustion catalyst, characterized in that it is prepared using the above-described preparation method. The preparation method can be found in the description of the prior embodiments, and will not be repeated here.
[0120] The present invention will be described in more detail below with reference to comparative examples and experimental examples.
[0121] The CO conversion rate test method described in the embodiments and comparative examples of this invention is as follows: 5g of catalyst is loaded into a fixed-bed reactor. Under normal pressure, a gas containing 2% CO, 20% CO2, 4% O2, 5% H2O, and the remainder being nitrogen is introduced into the reactor inlet. The temperature is slowly increased until the bed temperature reaches 120°C and stabilized for 2 hours. The outlet CO concentration is recorded, and the conversion rate is calculated from the outlet CO concentration. The conversion rate calculation formula is as follows:
[0122]
[0123] Comparative Example 1:
[0124] Step A': The waste methanol synthesis catalyst is crushed into powder with a particle size of less than 75 μm;
[0125] Step B': Add 174g of the powder described in step A' to the kneader, add 11g of pseudoboehmite, and dry mix for 20 minutes;
[0126] Step C': Add 80g of water, wet mix for 20 minutes, and then extrude into strips;
[0127] Step D': Dry until the water content is less than 5%;
[0128] Step E' involves calcining the catalyst at 500°C for 3 hours to obtain the final product, which is referred to as control sample 1.
[0129] Tests showed that the CO conversion rate of the control sample 1 was 35%, and the radial crushing force was 60 N / cm.
[0130] Example 1
[0131] Step A: Crush the waste methanol synthesis catalyst to a particle size of less than 30 μm;
[0132] Step B: Place the powder obtained in Step A at 420°C and calcine it in an oxygen-containing atmosphere for 3 hours, then cool it to room temperature.
[0133] Step C: Repeatedly wash and filter the calcined powder obtained in step B until the weight percentage of Na is less than 0.04%, the Cl content is less than 0.03%, and the S content is less than 0.03%, and collect the filter cake.
[0134] Step D: Dry the filter cake obtained in step C until the water content is less than 1%;
[0135] Step E: Crush the material obtained from drying in step D to less than 15μm to obtain the treated catalyst powder; for the following operations, the amount and proportion of each material added are shown in the ingredient table 1.
[0136] Table 1. Ingredient list for modified alumina and molding preparation steps.
[0137]
[0138] Step F: Dissolve and disperse the aluminate coupling agent in petroleum ether to obtain an aluminate coupling agent dispersion;
[0139] Step G: Add the powder obtained in step E and the aluminate coupling agent dispersion to the kneader and knead for 40 minutes;
[0140] Step H: Add gibbsite trihydrate and knead for 30 minutes;
[0141] Step 1: Add PEO and knead for 30 minutes;
[0142] Step J: First add 20g of water and knead for 10 minutes, then add another 20g of water and knead for 20 minutes.
[0143] Step K: Add ammonium bicarbonate and knead for 20 minutes;
[0144] Step L: Add the remaining water in small amounts multiple times;
[0145] Step M: The material is extruded into strips and dried at 120°C for 3 hours, with a water content of 2.1%.
[0146] Step N involves calcining the catalyst at 370°C for 3 hours to obtain the carbon monoxide catalytic combustion catalyst, resulting in sample 1.
[0147] Tests showed that sample 1 had a CO conversion rate of 100% and a radial crushing force of 110 N / cm.
[0148] Example 2:
[0149] This embodiment is similar to Embodiment 1, except that: ① in step A, the waste methanol synthesis catalyst is crushed to a particle size of less than 50 μm; ② in step B, the powder obtained in step A is placed at 500°C and calcined in an oxygen-containing atmosphere for 5 hours. Sample 2 was obtained through Embodiment 2.
[0150] Tests showed that sample 2 had a CO conversion rate of 98% and a radial crushing force of 108 N / cm.
[0151] Example 3:
[0152] This embodiment is similar to Embodiment 1, except that: ① In step C, the calcined powder obtained in step B is repeatedly washed and filtered with water until the Na content is less than 0.08%, the Cl content is less than 0.05%, and the S content is less than 0.05%; ② In step B, the powder obtained in step A is placed at 500°C and calcined in an oxygen-containing atmosphere for 5 hours. Sample 3 was obtained through Embodiment 3.
[0153] Tests showed that sample 3 had a CO conversion rate of 97% and a radial crushing force of 109 N / cm.
[0154] Example 4:
[0155] This embodiment is similar to Embodiment 1, except that in steps F and G, the powder obtained in step E and the coupling agent are directly added to the kneader, kneaded for 20 minutes, and then petroleum ether is added and kneaded for another 20 minutes. Sample 4 is obtained after Embodiment 4.
[0156] Tests showed that sample 4 had a CO conversion rate of 98% and a radial crushing force of 98 N / cm.
[0157] Example 5:
[0158] This embodiment is similar to Embodiment 1, except that in step F, the amount of aluminate coupling agent used is 2g and the amount of petroleum ether used is 24g. After Embodiment 5, Sample 5 was obtained.
[0159] Tests showed that sample 5 had a CO conversion rate of 93% and a radial crushing force of 120 N / cm.
[0160] Example 6:
[0161] This embodiment is similar to Embodiment 1, except that in step H, the amount of gibbsite added is 6g. After Embodiment 6, sample 6 was obtained.
[0162] Tests showed that sample 6 had a CO conversion rate of 100% and a radial crushing force of 85 N / cm.
[0163] This concludes the description of the various embodiments of the present invention. Based on the above description, those skilled in the art should have a clear understanding of the present invention.
[0164] It should be noted that, unless explicitly stated otherwise, the numerical parameters in the specification and claims of this invention may be approximate values and can be changed according to the content of this invention. Specifically, all figures in the specification and claims indicating the content of composition, reaction conditions, etc., should be understood to be modified by the term "about" in all cases, which means that they include a specific quantity varying by ±10% in some embodiments.
[0165] The ordinal numbers, such as "first," and Arabic numerals, letters, etc., used in the specification and claims to modify the corresponding elements (or steps) are intended only to make one element (or step) with a certain name clearly distinguishable from another element (or step) with the same name, and do not imply that the element (or step) has any ordinal number, nor do they represent the order of one element (or step) with another element (or step).
[0166] Furthermore, unless otherwise specified or required to occur in sequence, the order of the above steps is not limited to those listed above and may be varied or rearranged as needed for the design.
[0167] Those skilled in the art will understand that in the claims and specification of this invention, the word "comprising" does not exclude the presence of elements (or steps) not listed in the claims. The word "a" or "an" preceding an element (or step) does not exclude the presence of a plurality of such elements (or steps).
[0168] For certain implementation methods, if they are not key aspects of this invention and are well-known to those skilled in the art, they are not described in detail in the accompanying drawings or text due to space limitations. In such cases, they can be understood by referring to relevant prior art.
[0169] Furthermore, the above embodiments are provided only to enable the invention to meet legal requirements, and the invention can be implemented in many different forms and should not be construed as limited to the embodiments set forth herein.
[0170] Similarly, it should be understood that, for the sake of brevity, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof. However, this method of invention should not be construed as reflecting an intention that the claimed invention requires more features than expressly recited in each claim. Rather, as reflected in the claims, the various inventive aspects consist of fewer than all the features of the preceding single embodiment. Furthermore, embodiments may be used in combination with each other or with other embodiments based on design and reliability considerations; that is, technical features from different embodiments can be freely combined to form more embodiments. Therefore, the claims following the detailed description are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of the invention.
[0171] The above specific embodiments have provided a detailed description of the purpose, technical means, and beneficial effects of the present invention. It should be understood that the purpose of the detailed description is to enable those skilled in the art to better understand the present invention, and it is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing a catalyst for catalytic combustion of carbon monoxide, characterized in that, include: Step A: The waste copper-based methanol synthesis catalyst is crushed until the particle size is less than 50 μm to obtain the first powder; Step B involves calcining the first powder at a temperature between 380 and 420°C for 3 to 5 hours, in an oxygen-containing atmosphere with an oxygen content of ≥15%. Step C: Wash and filter the first powder after calcination to obtain filter cake material; The first powder after calcination is repeatedly washed and filtered with water until the following weight percentages are found: Na content less than 0.08%; Cl content less than 0.05%; and S content less than 0.05%. Step D: After drying the filter cake material, crush it to obtain the second powder; Step E: Add the second powder to the molding aid and knead to obtain a semi-finished product. Step E includes: Sub-step E1 involves mixing the second powder with a surface activator, wherein the surface activator comprises: an aluminate coupling agent and petroleum ether, wherein the aluminate coupling agent is isopropyl distearate aluminate, and its weight percentage content is between 0.1% and 2%; the mass of the petroleum ether is 5 to 20 times the mass of the aluminate coupling agent; Sub-step E2: Add a bridging agent and continue kneading, wherein the bridging agent is gibbsite material, and the weight percentage content of the gibbsite is between 2% and 10%. Sub-step E3: Add molding aids and continue kneading; Step F involves shaping the semi-finished material and then drying and calcining it to obtain a carbon monoxide catalytic combustion catalyst.
2. The production method according to claim 1, characterized by, In step A, the waste copper-based methanol synthesis catalyst is used as a reference per unit mass. The waste copper-based methanol synthesis catalyst contains: CuO, with a weight percentage content of not less than 50%; Al2O3, with a weight percentage content of not less than 10%; ZnO, with a weight percentage content of not less than 10%.
3. The preparation method according to claim 1, characterized in that, Step E1 includes: dissolving and dispersing the aluminate coupling agent in petroleum ether to obtain an aluminate coupling agent dispersion; adding the second powder and the aluminate coupling agent dispersion to a kneader for mixing; or adding the second powder and the aluminate coupling agent to a kneader for solid-solid mixing; adding petroleum ether to the kneader and continuing to mix. And / or, in the surfactant of sub-step E1, the weight percentage content of the aluminate coupling agent is between 0.3% and 1%; the mass of the petroleum ether is 8 to 15 times the mass of the aluminate coupling agent.
4. The preparation method according to claim 1, characterized in that, In sub-step E2, the weight percentage content of the gibbsite is between 3% and 6%.
5. The preparation method according to claim 1, characterized in that, In sub-step E3, the molding aid includes: PEO and ammonium bicarbonate, wherein the weight percentage of PEO is between 0.5% and 3%; and the weight percentage of ammonium bicarbonate is between 0.5% and 3%. And / or, the molding aid further includes one or more of the following materials: stearic acid, CMC-NH4, monoethanolamine, and ammonia.
6. The preparation method according to claim 5, characterized in that, In sub-step E3, the molding aid contains PEO at a weight percentage between 1% and 3%, and ammonium bicarbonate at a weight percentage between 0.5% and 2%.
7. The preparation method according to claim 1, characterized in that, Step D includes: Sub-step D1 involves drying the filter cake material at a temperature between 100℃ and 300℃. Sub-step D2 involves crushing the dried filter cake material to a particle size of less than 50 μm. And / or, step F includes: Sub-step F1 involves shaping the semi-finished material using one of the following processes: extrusion molding, ball rolling molding, honeycomb extrusion molding, or coating molding. Sub-step F2 involves drying the shaped material to reduce its moisture content to below 5%. Sub-step F3 involves roasting the dried material at a temperature of 300-500℃.
8. A carbon monoxide catalytic combustion catalyst characterized by comprising, Prepared by the preparation method according to any one of claims 1 to 7.