CO monolithic catalysts with water and sulfur resistance, and preparation method and application thereof

Abstract

The application belongs to the field of separation, and particularly relates to a CO monolithic catalyst with water resistance and sulfur resistance, and a preparation method and application thereof. The preparation method comprises the following steps: 1) uploading a non-noble metal additive coating; 2) uploading an alkaline earth metal additive coating; and 3) noble metal modification. The monolithic catalyst can maximize the reduction of the amount of noble metal, save the cost and achieve the optimal catalytic effect by regulating the ratio between the noble metal and the alkaline earth metal. In addition, the strong interaction between the noble metal, the alkaline earth metal and the Ti, Al, Sn, Ce and Zr additive coatings inhibits the weak adsorption of SO2 on the surface of the catalyst, reduces the desorption temperature of the strongly adsorbed SO2 and the decomposition temperature of the sulfate, and exhibits good catalytic activity and sulfur resistance.

Description

Technical Field

[0001] This invention belongs to the field of separation, specifically relating to a monolithic CO catalyst with water and sulfur resistance, its preparation method, and its application. Background Technology

[0002] CO has a wide range of sources and large emissions, making it one of the six basic pollutants controlled in my country's "Ambient Air Quality Standards". CO in the environment mainly originates from fossil fuel combustion in industries such as metallurgy and chemicals, and waste incineration. Due to current limitations in combustion technology, a large amount of CO is emitted into the environment. Catalytic oxidation, as the mainstream end-of-pipe treatment technology, has become the primary means of CO treatment. However, because CO waste gas has a very complex composition, sulfides and H2O can easily cause catalyst deactivation. Therefore, developing a monolithic CO catalyst with high efficiency and resistance to water and sulfur has become a top priority. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a monolithic CO catalyst with water and sulfur resistance, its preparation method and application.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A method for preparing a monolithic CO catalyst with water and sulfur resistance includes the following steps: 1) Loading a non-precious metal additive coating: placing a dried support in a slurry containing a non-precious metal additive compound, and drying and calcining it after impregnation to obtain a support with a non-precious metal additive coating; 2) Loading an alkaline earth metal additive coating: impregnating the support with the non-precious metal additive coating obtained in step 1) in a slurry containing an alkaline earth metal compound, and drying and calcining it after impregnation to obtain a support with an alkaline earth metal additive coating; 3) Precious metal modification: impregnating the support with the alkaline earth metal additive coating obtained in step 2) in a slurry containing a precious metal compound, and drying and calcining it after impregnation to obtain a monolithic CO catalyst with water and sulfur resistance.

[0006] The non-precious metal auxiliary compound in step 1) is one or any combination of Ti, Al, Sn, Ce, and Zr.

[0007] The non-precious metal additive compound in step 1) is a compound containing at least three combinations of Ti, Al, and Sn.

[0008] The molar ratio of Ti, Al, and Sn is 4:1:0.2-1.

[0009] The non-precious metal auxiliary compound in step 1) is a compound consisting of five combinations of Ti, Al, Sn, Ce, and Zr.

[0010] The molar ratio of Ti, Al, Sn, Ce, and Zr is 4:1:0.2-0.8:0.2-0.5:0.2-0.5.

[0011] In step 2), the alkaline earth metal compound is one or a combination of Ba and Ca; preferably, it is a compound of Ba and Ca, with a molar ratio of Ba:Ca of 1-2:1-2, and more preferably a molar ratio of Ba:Ca of 2:1.

[0012] Preferably, the noble metal compound in step 3) is a compound of one or a combination of Pt and Pd, and preferably, the molar ratio of Pt to Pd is 3:1.

[0013] The calcination temperature in steps 1), 2), and 3) is independently 500-600℃, preferably 550℃; preferably, microwave drying is used to remove residual solution before calcination; preferably, the carrier is cordierite; preferably, the carrier is 46-200 mesh; preferably 200 mesh.

[0014] The present invention also includes a monolithic CO catalyst with water and sulfur resistance obtained by the preparation method described above.

[0015] The present invention also includes an application of the catalyst described herein for the treatment of CO.

[0016] A monolithic catalyst mainly consists of three parts: the active component, the coating, and the support. The active component, attached to the surface of the coating, provides active sites for the catalytic reaction and is the core of the catalyst, determining its performance. Currently, common active components are mainly noble metals such as Pt, Pd, and Au, which can decompose CO at relatively low temperatures. However, the high cost and sintering nature of noble metals limit their use to some extent. The coating is a substance uniformly applied to the surface of the support, increasing the specific surface area of ​​the support, enhancing the bonding force between the active component and the support, and improving the efficiency of the active component. In this application, non-noble metals such as Ti, Sn, and Ce are used, which significantly promote CO conversion under aqueous conditions and exhibit strong stability under complex conditions. Alkaline earth metal oxide catalysts such as Ba and Ca are relatively inexpensive and widely available compared to noble metal catalysts, and can be used as promoters to effectively regulate the noble metal content. Utilizing the synergistic effect between the promoter coating and the noble metal active component can effectively improve the catalyst's efficiency and lifespan while reducing its cost. The support is the basic framework of the catalyst. It not only provides support, but its regular pore structure also facilitates the flow of reactants and products, thereby reducing the thermal accumulation effect during the exothermic reaction.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] 1. This invention utilizes a solution impregnation method to load the additive coating and active components, eliminating the need for additional binders and effectively ensuring that all catalyst components are uniformly dispersed on the carrier surface and in the carrier pores.

[0019] 2. The additive coating in the integral catalyst of the present invention can dissociate H2O in the gas component into hydroxyl species to participate in the reaction, thus ensuring the high catalytic activity and stability of the catalyst under water-containing conditions.

[0020] 3. The alkaline earth metal coating in the monolithic catalyst of the present invention can effectively regulate the particle size and dispersibility of noble metals, thereby improving the chemical adsorption and activation capacity of CO and O2 on the catalyst surface.

[0021] 4. The monolithic catalyst described in this invention, by controlling the ratio between precious metals and alkaline earth precious metals, can minimize the amount of precious metals used, save costs, and achieve optimal catalytic effect. Furthermore, the strong interaction between the precious metals, alkaline earth metals, and the Ti, Al, Sn, Ce, and Zr additive coatings suppresses the weak adsorption of SO2 on the catalyst surface, lowers the desorption temperature of strongly adsorbed SO2 and the decomposition temperature of sulfates, exhibiting good catalytic activity and sulfur resistance.

[0022] 5. The monolithic catalyst described in this invention has good CO catalytic conversion efficiency and has good practical application value and prospects. Attached image description:

[0023] Figure 1 This invention compares the effects of Ti, Al, Sn, Ce, and Zr additive coatings on CO conversion rate.

[0024] Figure 2 This invention compares the effect of alkaline earth metal additive coatings on CO conversion rate.

[0025] Figure 3 This is a graph showing the long-term stability test of catalyst A against CO in Example 1 of this invention. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and preferred embodiments.

[0027] Example 1: A method for preparing a monolithic CO catalyst with water and sulfur resistance, specifically including the following steps:

[0028] 1) The dried cordierite carrier (200 mesh, length × width × height = 10cm × 10cm × 10cm) was immersed in a mixed solution of titanium sulfate, aluminum nitrate, stannous sulfate, cerium nitrate hexahydrate and zirconium nitrate pentahydrate with a molar ratio of Ti, Al, Sn, Ce, Zr of 4:1:0.8:0.2:0.2 for 10 min. Then the residual liquid on the inner and outer walls of the cordierite was blown off, and then it was placed in a microwave drying device for rapid drying to obtain the carrier for 10 min.

[0029] 2) The support obtained in step 1) was placed in a muffle furnace and calcined at 550°C for 4 hours with a heating rate of 5°C / min under dry air atmosphere to obtain the catalyst.

[0030] 3) The catalyst obtained in step 2) was immersed in a mixed solution of barium acetate and calcium acetate with a Ba:Ca molar ratio of 2:1 for 10 min. Then, the residual liquid on the inner and outer walls of the cordierite was blown off, and then the catalyst was placed in a microwave drying device for rapid drying to obtain the carrier for 10 min.

[0031] 4) The support obtained in step 3) was placed in a muffle furnace and calcined at 550°C for 4 hours with a heating rate of 5°C / min under dry air atmosphere to obtain the catalyst.

[0032] 5) The catalyst obtained in step 4) was immersed in a mixed solution of chloroplatinic acid and palladium chloride with a Pt:Pd molar ratio of 3:1 for 10 min. Then, the residual liquid on the inner and outer walls of the cordierite was blown off, and then the catalyst was placed in a microwave drying device for rapid drying to obtain the support for 10 min.

[0033] 6) The catalyst obtained in step 5) is placed in a muffle furnace and calcined at 550°C for 4 hours with a heating rate of 5°C / min. After calcination and cooling, a monolithic CO catalyst A with water and sulfur resistance is obtained, wherein the catalyst weight gain ratio is 5.56%.

[0034] Example 2: A method for preparing a water- and sulfur-resistant monolithic CO catalyst. The basic synthesis steps are the same as in Example 1, except that in step 1), the catalyst is immersed in a solution of Ti, Al, Sn, Ce, and Zr in a molar ratio of 4:1:0.4:0.4:0.4 for 10 minutes. Other steps are the same as in Example 1, thus obtaining a water- and sulfur-resistant monolithic CO catalyst B, wherein the catalyst weight gain is 5.45%.

[0035] Example 3: A method for preparing a water- and sulfur-resistant monolithic CO catalyst. The basic synthesis steps are the same as in Example 1, except that in step 1), the catalyst is immersed in a solution of Ti, Al, Sn, Ce, and Zr in a molar ratio of 4:1:0.2:0.5:0.5 for 10 minutes. Other steps are the same as in Example 1, thus obtaining a water- and sulfur-resistant monolithic CO catalyst C, wherein the catalyst weight gain is 5.68%.

[0036] Example 4: A method for preparing a water- and sulfur-resistant monolithic CO catalyst. The basic synthesis steps are the same as in Example 1. The difference is that in step 1), the catalyst is immersed in a solution of Ti, Al and Sn in a molar ratio of 4:1:1 for 10 min. Other steps are the same as in Example 1. A water- and sulfur-resistant monolithic CO catalyst D is obtained, wherein the catalyst weight gain ratio is 5.35%.

[0037] Example 5: A method for preparing a water- and sulfur-resistant monolithic CO catalyst. The basic synthesis steps are the same as in Example 1. The difference is that in step 1), the catalyst is immersed in a solution of Ti, Al, and Sn in a molar ratio of 2:1:1 for 10 minutes. Other steps are the same as in Example 1. A water- and sulfur-resistant monolithic CO catalyst E can be obtained, wherein the catalyst weight gain ratio is 5.28%.

[0038] Example 6: A method for preparing a water- and sulfur-resistant monolithic CO catalyst. The basic synthesis steps are the same as in Example 1. The difference is that in step 3), the catalyst is immersed in a solution with a Ba:Ca molar ratio of 1:2 for 10 min. Other steps are the same as in Example 1. A water- and sulfur-resistant monolithic CO catalyst F can be obtained, wherein the catalyst weight gain ratio is 5.67%.

[0039] Example 7: A method for preparing a water- and sulfur-resistant monolithic CO catalyst. The basic synthesis steps are the same as in Example 1, except that in step 1), the size of the cordierite is changed to 46 mesh, with a length × width × height of 15cm × 15cm × 20cm. Other steps are the same as in Example 1, thus obtaining a water- and sulfur-resistant monolithic CO catalyst G, wherein the catalyst weight gain ratio is 8.34%.

[0040] Comparative Example 1: A method for preparing a water- and sulfur-resistant monolithic CO catalyst, the basic synthesis steps of which are the same as those in Example 1, the difference being that in step 1), the cordierite support is immersed in a solution with a Sn:Ce:Zr molar ratio of 0.8:0.2:0.2 for 10 min, and the other steps are the same as in Example 1, thus obtaining a water- and sulfur-resistant monolithic CO catalyst H, wherein the catalyst weight gain ratio is 1.06%.

[0041] Comparative Example 2: A method for preparing a water- and sulfur-resistant monolithic CO catalyst, the basic synthesis steps of which are the same as those in Example 1, the difference being that in step 1), the cordierite support is immersed in a solution with a Ti:Al:Ce:Zr molar ratio of 4:1:0.2:0.2 for 10 min, and the other steps are the same as in Example 1, thus obtaining a water- and sulfur-resistant monolithic CO catalyst I, wherein the catalyst weight gain ratio is 5.08%.

[0042] Comparative Example 3: A method for preparing a water- and sulfur-resistant monolithic CO catalyst. The basic synthesis steps are the same as those in Example 1. The difference is that in step 3), the cordierite support is immersed in a calcium acetate solution for 10 minutes. Other steps are the same as in Example 1. A water- and sulfur-resistant monolithic CO catalyst J can be obtained, wherein the catalyst weight gain ratio is 5.29%.

[0043] Comparative Example 4: A method for preparing a water- and sulfur-resistant monolithic CO catalyst. The basic synthesis steps are the same as those in Example 1. The difference is that in step 3), the cordierite support is immersed in a barium acetate solution for 10 minutes. Other steps are the same as in Example 1. A water- and sulfur-resistant monolithic CO catalyst K can be obtained, wherein the catalyst weight gain ratio is 5.33%.

[0044] Comparative Example 5: A method for preparing a water- and sulfur-resistant monolithic CO catalyst, the basic synthesis steps of which are the same as those in Example 1, except that steps 1) and 2) are not included, thus obtaining a water- and sulfur-resistant monolithic CO catalyst L, wherein the catalyst weight gain ratio is 0.17%.

[0045] Comparative Example 6: A method for preparing a water- and sulfur-resistant monolithic CO catalyst, the basic synthesis steps of which are the same as those in Example 1, except that steps 3) and 4) are not included. A water- and sulfur-resistant monolithic CO catalyst M can be obtained, wherein the catalyst weight gain ratio is 5.52%.

[0046] It should be noted that the comparative examples in this application are set up for comparison with the embodiments, and are themselves part of the embodiments.

[0047] The prepared example catalysts were subjected to a fixed-bed reaction with the comparative catalysts. The CO gas concentration was 15,000 ppm, the O2 concentration was 12 vol.%, the SO2 concentration was 50 ppm, the water content was 25%, N2 was the equilibrium gas, and the gas space velocity was 24,000 h⁻¹. -1 The reaction temperature was 250℃. Catalyst activity was tested under these conditions, and the results for CO testing are shown in Table 1.

[0048] Table 1

[0049]

[0050]

[0051] The effect of compounds on the coating of Ti, Al, Sn, Ce, and Zr additives is shown in Comparative Example 1 (Ti:Al:Sn:Ce:Zr = 4:1:0.8:0.2:0.2), Example 2 (Ti:Al:Sn:Ce:Zr = 4:1:0.4:0.4:0.4), Example 3 (Ti:Al:Sn:Ce:Zr = 4:1:0.2:0.5:0.5), Example 4 (Ti:Al:Sn = 4:1:1), Example 5 (Ti:Al:Sn = 2:1:1), Comparative Example 1 (Sn:Ce:Zr = 0.8:0.2:0.2), Comparative Example 2 (Ti:Al:Ce:Zr = 4:1:0.2:0.2), and Comparative Example 5 (without Ti, Al, Sn, Ce, Zr additive coating). See Table 1 and... Figure 1 It is evident that combining Ti, Al, and Sn compounds in a Ti, Al, Sn, Ce, and Zr additive coating at 250℃ achieves a relatively ideal effect on CO treatment, far superior to the combinations of Ti, Al, and Ce, Zr, or Sn and Ce, Zr compounds. Among these three combinations, the molar ratio Ti:Al:Sn = 4:1:1 shows the best effect. Adding appropriate amounts of Ce and Zr to the Ti, Al, and Sn compounds can effectively improve the CO conversion efficiency under these conditions, with the optimal molar ratio Ti:Al:Sn:Ce:Zr = 4:1:0.8:0.2:0.2.

[0052] The effect of the compound on the coating loaded with alkaline earth metal additives is shown in Examples 1 (Ba:Ca = 2:1), 5 (Ba:Ca = 1:2), Comparative Example 3 (Ca component only), Comparative Example 4 (Ba component only), and Comparative Example 6 (no alkaline earth metal additive coating). See Table 1 and... Figure 2 It is evident that in the loaded alkaline earth metal additive coating, the alkaline earth metal coating effectively controls the particle size and dispersibility of the noble metal, improving the chemical adsorption and activation capacity of CO and O2 on the catalyst surface. Therefore, the catalyst with loaded alkaline earth metal exhibits superior performance compared to the catalyst without an alkaline earth metal coating. When only one alkaline earth metal is loaded, the activity of the Ba component is significantly better than that of the Ca component alone. Adding an appropriate amount of Ca component to the Ba component can effectively improve the conversion efficiency of the catalyst under these conditions, with the optimal molar ratio of Ba:Ca = 2:1 being the most effective.

[0053] The effect of catalyst support is shown in Example 1 (200 mesh support) and Example 7 (46 mesh support).

[0054] Figure 3Catalyst A prepared in the optimal embodiment 1 has an SO2 concentration of 50 ppm, a water content of 25%, a CO gas concentration of 15000 ppm, an O2 concentration of 12 vol.%, and a gas hourly space velocity of 24000 h⁻¹. -1 Even after catalytic oxidation at a reaction temperature of 250℃ for 100 hours, the conversion rate still remains above 99%, demonstrating the excellent sulfur and water resistance of this catalyst.

[0055] In summary, this invention utilizes a solution impregnation method to load the auxiliary coating and active components, eliminating the need for additional binders and effectively ensuring uniform dispersion of catalyst components on the support surface and within the support pores. The auxiliary coating in the monolithic catalyst of this invention can dissociate H2O in the gaseous component into hydroxyl species to participate in the reaction, ensuring high catalytic activity and stability of the catalyst under aqueous conditions. The alkaline earth metal coating in the monolithic catalyst of this invention can effectively regulate the particle size and dispersibility of noble metals, thereby improving the chemical adsorption and activation capacity of CO and O2 on the catalyst surface. By controlling the ratio between noble metals and alkaline earth noble metals, the monolithic catalyst of this invention can maximize the reduction of noble metal usage, saving costs and achieving optimal catalytic effect. Furthermore, the strong interaction between noble metals, alkaline earth metals, and Ti, Al, Sn, Ce, and Zr auxiliary coatings inhibits the weak adsorption of SO2 on the catalyst surface, lowers the desorption temperature of strongly adsorbed SO2 and the decomposition temperature of sulfates, exhibiting good catalytic activity and sulfur resistance. The monolithic catalyst of this invention has good CO catalytic conversion efficiency and good practical application value and prospects.

[0056] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a monolithic CO catalyst with water and sulfur resistance, characterized in that, Includes the following steps: 1) Loading a non-precious metal additive coating: The dried carrier is placed in a slurry containing a non-precious metal additive compound, and after impregnation, it is dried and calcined to obtain a carrier containing a non-precious metal additive coating. The non-precious metal additive compounds are compounds composed of five combinations of Ti, Al, Sn, Ce, and Zr. The molar ratio of Ti, Al, Sn, Ce, and Zr is 4:1:0.2-0.8:0.2-0.5:0.2-0.5; 2) Loading alkaline earth metal additive coating: The carrier containing the non-precious metal additive coating obtained in step 1) is immersed in a slurry containing alkaline earth metal compounds. After immersion, it is dried and calcined to obtain a carrier containing an alkaline earth metal additive coating. Alkaline earth metal compounds are compounds composed of Ba and Ca. The molar ratio of Ba to Ca is 1-2:1-2; 3) Noble metal modification: The carrier containing the alkaline earth metal additive coating obtained in step 2) is impregnated in a slurry containing a noble metal compound. After impregnation, it is dried and calcined to obtain a monolithic CO catalyst with water and sulfur resistance.

2. The method for preparing the monolithic CO catalyst with water and sulfur resistance according to claim 1, characterized in that, In step 3), the noble metal compound is one or a combination of Pt and Pd.

3. The method for preparing the monolithic CO catalyst with water and sulfur resistance according to claim 1, characterized in that, Noble metal compounds are compounds composed of Pt and Pd, with a Pt:Pd molar ratio of 3:

1.

4. The method for preparing the monolithic CO catalyst with water and sulfur resistance according to claim 1, characterized in that, The calcination temperature in steps 1), 2), and 3) is independently 500-600℃. Microwave drying is used to remove residual solution before calcination. The carrier is cordierite and has a mesh size of 46-200.

5. The method for preparing the monolithic CO catalyst with water and sulfur resistance according to claim 1, characterized in that, The calcination temperature in steps 1), 2), and 3) is independently 550°C; the carrier is 200 mesh.

6. A monolithic CO catalyst with water and sulfur resistance prepared by the preparation method according to any one of claims 1-5.

7. The application of the catalyst according to claim 6, characterized in that, It is used for CO processing.

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