A sulfur-resistant catalytic combustion catalyst and its preparation method and application

Abstract

The invention discloses a sulfur-resistant catalytic combustion catalyst and its preparation method and application, which belongs to the technical field of sulfur-resistant catalytic combustion catalyst. The catalyst uses high-temperature porous titanium-containing activated alumina as an active carrier, precious metals as an active component, and non-precious metals as an auxiliary agent; the precious metal is selected from at least one of platinum and palladium; the precious metal accounts for 0.05-1.0% of the total mass of the catalyst; the auxiliary agent accounts for 0.1-10% of the total mass of the catalyst. The method for preparing a sulfur-resistant catalytic combustion catalyst of the present invention adopts a step-by-step high-temperature open flame roasting process, and the precious metal and the auxiliary agent are loaded on the surface of a spherical high-temperature porous titanium-containing activated alumina to prepare an "eggshell-type" catalyst, which makes the most of the activity of the precious metal, thereby improving the catalytic activity and sulfur resistance of the prepared catalyst, saving the amount of precious metals, and reducing the catalyst cost. It is suitable for use in sulfur-containing VOCs environmental protection treatment occasions with high gas source pressure and high non-methane total hydrocarbon conversion rate; the catalyst preparation process of the present invention is simple and environmentally friendly.

Description

Technical Field

[0001] The invention relates to the technical field of sulfur-resistant catalytic combustion catalysts, and in particular to a sulfur-resistant catalytic combustion catalyst and a preparation method and application thereof. Background Art

[0002] Volatile organic compounds (VOCs) are a major atmospheric pollutant produced in the petroleum refining industry as well as the electronics, printing, and coating processing industries. Large amounts of organic waste gas emitted seriously endanger human health. Catalytic combustion, as a method of VOCs control, refers to the deep oxidation of organic molecules on the surface of the catalyst under the action of a catalyst, which converts organic waste gas into harmless carbon dioxide and water. Therefore, catalytic combustion is also called catalytic oxidation or catalytic deep oxidation. As a simple and practical organic waste gas purification technology, catalytic combustion is gaining more and more attention.

[0003] However, in the petroleum processing industry and downstream fine chemical industry, such as the waste gas from the wastewater treatment plant of the petroleum refinery, there are sulfur-containing gases such as hydrogen sulfide, carbonyl sulfide, methyl mercaptan, ethyl mercaptan, methyl sulfide, ethyl sulfide, carbon disulfide, dimethyl disulfide, sulfur dioxide, etc.; the waste gas discharged by pharmaceutical factories, pesticide factories and chemical fiber factories during production contains sulfur-containing pollutants such as CH3SH, CH3CH2SH, CS2, etc. These gases with bad odors seriously stimulate people's olfactory organs, causing discomfort or disgust, and are seriously harmful to human health.

[0004] Ordinary catalytic combustion catalysts generally use alumina as a carrier and precious metals as a material. In a sulfur-containing atmosphere, the catalyst is easily permanently poisoned, resulting in a decrease in activity or even deactivation. Pre-desulfurization of the reaction gas increases the investment and operating costs of the catalytic combustion device. Therefore, it is of great significance to develop sulfur-resistant catalytic combustion catalysts.

[0005] Patents CN108114745A, CN102909020A and CN105536823A respectively disclose sulfur-resistant catalytic combustion catalysts and preparation methods thereof. The prepared sulfur-resistant catalytic combustion catalysts are suitable for the treatment of VOCs at lower pressures. This type of preparation method mainly uses honeycomb ceramics as a substrate, and loads precious metals and additives on the substrate by preparation methods such as impregnation and coating. However, the preparation process is complicated and the cost is high, and the catalyst has poor sulfur resistance and catalytic activity. Summary of the invention

[0006] The present invention provides a sulfur-resistant catalytic combustion catalyst and a preparation method and application thereof to solve the above problems.

[0007] In order to achieve the above object, the technical solution of the present invention is:

[0008] On one hand, the present invention provides a sulfur-resistant catalytic combustion catalyst, which uses titanium-containing high-temperature porous activated alumina as an active carrier, noble metals as active ingredients, and non-noble metals as additives;

[0009] The noble metal is selected from at least one of platinum and palladium; the noble metal accounts for 0.05-1.0% of the total mass of the catalyst;

[0010] The additive accounts for 0.1-10% of the total mass of the catalyst.

[0011] Furthermore, the titanium-containing high-temperature porous active alumina is α-alumina loaded with titanium, and the titanium accounts for 5-30% of the total mass of the active carrier.

[0012] Furthermore, the titanium-containing high-temperature porous activated alumina is spherical, and its particle size is 2-6 mm.

[0013] Furthermore, the auxiliary agent is one or more of cerium Ce, lanthanum La, copper Cu, zirconium Zr, iron Fe, and chromium Cr.

[0014] Another aspect of the present invention provides a method for preparing the sulfur-resistant catalytic combustion catalyst, comprising the following steps:

[0015] S1: dissolving a sponge-state noble metal in aqua regia to obtain a noble metal salt solution, dissolving an auxiliary agent nitrate in an organic solvent to obtain a solution, and mixing the noble metal salt solution with the solution to prepare an impregnation solution;

[0016] S2: adding the impregnation solution prepared in step S1 evenly to the titanium-containing high-temperature porous activated alumina support rolling in the rolling ball pot;

[0017] S3: The product after impregnation in step S2 is subjected to stepwise high-temperature roasting treatment;

[0018] S4: Cool the product after the calcination treatment in step S3 to room temperature, then add hydrazine hydrate with a concentration of 0.1-8wt% for reduction treatment, the reduction treatment time is 2-8h, and after the reduction treatment, it is washed and dried to obtain a finished catalyst.

[0019] Furthermore, in step S1, the organic solvent is selected from alkanes, alcohols or organic acids.

[0020] Furthermore, in step S2, the specific method of adding the impregnation liquid prepared in step S1 to the titanium-containing high-temperature porous activated alumina carrier is: adding the titanium-containing high-temperature porous activated alumina carrier to a rolling ball pot, and while the carrier is rolling, adding the impregnation liquid to the rolling ball pot at a rate of 50-200 ml / min.

[0021] Furthermore, in step S3, the specific method of the step-by-step high-temperature roasting treatment is:

[0022] The first stage: directly ignite the product after impregnation in step S2 in a combustion furnace, place the ignited impregnated product in a vibrating screen and burn it with an open flame while vibrating until it is naturally extinguished, and the frequency of the vibrating screen is 10-20Hz;

[0023] The second stage: high temperature calcination at 400-650℃ for 1.5-4h.

[0024] Further, in step S4, washing is performed with a washing liquid after the reduction treatment, wherein Cl - Less than 10ppm; drying temperature is 120-150℃, drying time is 2-6h.

[0025] In another aspect, the present invention provides the use of the sulfur-resistant catalytic combustion catalyst or the sulfur-resistant catalytic combustion catalyst prepared by the preparation method of the sulfur-resistant catalytic combustion catalyst in the catalytic combustion of VOCs.

[0026] The beneficial effects of the present invention are:

[0027] (1) The method for preparing a sulfur-resistant catalytic combustion catalyst of the present invention adopts a step-by-step high-temperature open flame roasting process to load precious metals and additives on the surface of a spherical high-temperature porous titanium-containing activated alumina to prepare an "eggshell-type" catalyst, which maximizes the activity of the precious metals, thereby improving the catalytic activity and sulfur resistance of the prepared catalyst, saving the amount of precious metals, and reducing the catalyst cost. The catalyst is suitable for environmental protection treatment of sulfur-containing VOCs in situations where the gas source pressure is high and a high non-methane total hydrocarbon conversion rate is required;

[0028] (2) The catalyst preparation process of the present invention is simple, which minimizes the steps in catalyst production and manufacturing, reduces its production cost, and is environmentally friendly. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] The principle involved in the present invention:

[0031] Sulfur poisoning of precious metal catalysts is generally believed to be caused by the reaction between the active component or carrier in the catalyst and sulfur, resulting in the sulfidation or sulfation of the metal or carrier, which leads to the deactivation of the catalyst. This method uses titanium-containing α-alumina as a carrier and adds a certain amount of platinum and palladium as additives to effectively reduce the sulfidation or sulfation of the active component precious metal, thereby ensuring that the catalyst has a certain sulfur resistance performance;

[0032] At the same time, an organic solvent is used to dissolve the additive, and combined with the open flame roasting method in the subsequent roasting stage, the organic solvent can improve the dispersion of the precious metal active components on the carrier surface during the combustion process, and the active components can form an eggshell type (eggshell type catalyst) on the carrier surface, thereby effectively improving the utilization rate of the active components and the catalytic activity of the prepared sulfur-resistant catalytic combustion catalyst.

[0033] Example 1

[0034] A method for preparing a sulfur-resistant catalytic combustion catalyst comprises the following steps:

[0035] 20 g of sponge platinum is dissolved in about 200 ml of aqua regia to prepare a noble metal salt solution, 950 g of cerium nitrate hexahydrate is dissolved in 2.3 L of n-hexane to obtain a solution, the noble metal salt solution and the solution are mixed to prepare an impregnation solution, the amount of the impregnation solution is about 2.5 L;

[0036] S2: 2.5L of the impregnation solution prepared in step S1 is evenly added to the titanium-containing high-temperature porous activated alumina carrier rolling in the rolling ball pot, and the addition rate is 100ml / min; wherein the titanium-containing high-temperature porous activated alumina carrier is a spherical shape of 2-3mm, the titanium content is 5%, and the carrier mass is 10kg;

[0037] S3: The product after impregnation in step S2 is subjected to a stepwise high-temperature roasting treatment; the first stage: the product after impregnation in step S2 is directly ignited in a special combustion furnace, and the ignited impregnated product is placed in a vibrating screen and vibrated while burning with an open flame until it is naturally extinguished, and the frequency of the vibrating screen is 10Hz;

[0038] The second stage: the product after the first stage is placed in a high temperature furnace and calcined at 500°C for 2 hours.

[0039] S4: The product after the pretreatment in step S3 is cooled to room temperature, and then 2 wt% hydrazine hydrate is added for reduction treatment. The reduction treatment time is 3 h. After the reduction treatment, it is washed with deionized water. Cl - Less than 10ppm; the drying temperature is 120℃, the drying time is 2.5h, and the finished catalyst is obtained. The loading amount of precious metal platinum is 0.2%wt, and the additive accounts for 3% of the total mass of the catalyst.

[0040] Example 2

[0041] The only difference between this embodiment and embodiment 1 is that, in this embodiment, the amount of sponge platinum added is 5 g, the amount of cerium nitrate hexahydrate is 31.67 g, the loading amount of precious metal platinum is 0.05% wt, and the additive accounts for 0.1% of the total mass of the catalyst.

[0042] Example 3

[0043] The only difference between this embodiment and embodiment 1 is that, in this embodiment, the amount of sponge platinum added is 60 g, the auxiliary agent is cerium nitrate hexahydrate and chromium nitrate hexahydrate in a mass ratio of 2:1, the amount of auxiliary agent added is 1900 g, the loading amount of precious metal platinum is 0.6% wt, the auxiliary agent accounts for 6% of the total mass of the catalyst, and the organic solvent is alcohol.

[0044] Example 4

[0045] The only difference between this embodiment and embodiment 1 is that, in this embodiment, the amount of precious metal sponge platinum used is 100 g, the auxiliary agent is cerium nitrate hexahydrate and chromium nitrate nonahydrate in a mass ratio of 2:1, the amount of auxiliary agent added is 3167 g, the loading amount of precious metal platinum is 1.0% wt, the auxiliary agent accounts for 10% of the total mass of the catalyst, and the organic solvent is alcohol.

[0046] Example 5

[0047] The only difference between this embodiment and embodiment 1 is that, in this embodiment, 20g of precious metal sponge platinum and sponge palladium (the weight ratio of the two is 2:1), 950g of cerium nitrate hexahydrate and 4000g of chromium nitrate nonahydrate are used, the loading amount of precious metal platinum and palladium is 0.2%wt, the auxiliary agent accounts for 8% of the total mass of the catalyst, and the organic solvent is alcohol.

[0048] Example 6

[0049] The only difference between this embodiment and embodiment 1 is that, in this embodiment, 20g of precious metal sponge palladium, 950g of cerium nitrate hexahydrate and 4000g of chromium nitrate nonahydrate are added, the loading amount of precious metal palladium is 0.2%wt, the auxiliary agent accounts for 8% of the total mass of the catalyst, and the organic solvent is methanol.

[0050] Example 7

[0051] The only difference between this embodiment and embodiment 1 is that, in this embodiment, the titanium content of the titanium high temperature porous activated alumina carrier is 15%.

[0052] Example 8

[0053] The only difference between this embodiment and embodiment 1 is that, in this embodiment, the titanium content of the titanium-containing high-temperature porous activated alumina carrier is 30%.

[0054] Comparative Example 1:

[0055] The difference between this embodiment and embodiment 5 is that in this comparative example, no auxiliary agent is added.

[0056] Comparative Example 2:

[0057] The only difference between this embodiment and embodiment 5 is that in this comparative example, the organic solvent is replaced by water, and the step S3 is: the product after the impregnation in step S2 is subjected to high-temperature roasting treatment, placed in a high-temperature furnace, and high-temperature roasting treatment at 500°C for 2h, that is, the first stage of open flame roasting in the stepless roasting.

[0058] Comparative Example 3:

[0059] The only difference between this embodiment and embodiment 5 is that, in this comparative example, commercially available ordinary titanium-free α-alumina is used to replace the titanium-containing high-temperature porous activated alumina.

[0060] Performance testing

[0061] As a typical non-methane total hydrocarbon component in VOCs, the catalytic combustion conversion rate of ethane can represent the activity level of the catalytic combustion catalyst. Therefore, the performance test uses the ethane conversion rate as the detection indicator;

[0062] 1.0 g of the sulfur-resistant catalytic combustion catalysts prepared in Examples 1-8 and Comparative Examples 1-3 were respectively loaded into the catalytic bed layer of a laboratory catalyst fixed bed detection device, and the following tests were performed:

[0063] Experimental conditions: gas distribution (volume ratio): ethane C2H6: 2000ppm, hydrogen sulfide H2S: 100ppm, the rest is air. The test air velocity is 15000 / h, the reaction temperature is 400℃, normal pressure, and the ethane content is detected to calculate the conversion rate. The test time is 24 hours (after stabilization), sampling is performed every 8 hours, and the test results are averaged. The test results are shown in Table 1:

[0064]

[0065] From the data in Table 1, it can be seen that the ethane conversion rate of the catalyst prepared by the present method (Examples 1-8) at the 8th hour is all above 90%, indicating that the catalyst prepared by the present method has good catalytic activity, and the data at 16 o'clock and 24 o'clock are also higher than 90%, indicating that the catalyst prepared by the present method has good sulfur resistance; with the increase of the loading amount of the precious metal, the catalytic activity of the catalyst is improved; from the results of Example 1 and Examples 5-6, it can be seen that in terms of the catalytic performance of the catalyst, the precious metal palladium> palladium+platinum>platinum, and in terms of the sulfur resistance of the catalyst, the effect of using a single precious metal palladium is slightly worse than that of a single platinum and a combination of platinum and palladium; in addition, increasing the titanium content has little effect on the catalytic activity, therefore, from the perspective of economic applicability, it is considered to use α-alumina with a titanium content of 5% as a carrier;

[0066] Compared with Examples 1-8, no additive was added in Comparative Example 1, and its ethane conversion rate at 16 and 24 hours was greatly reduced, indicating that the addition of the additive can effectively improve the sulfur resistance of the catalyst; and the ethane conversion rate of Comparative Example 2 is much lower than that of the embodiment. It can be seen that the catalytic activity of the prepared catalyst is greatly reduced by not using open flame roasting and not using organic solvent to dissolve the auxiliary nitrate in the roasting stage; from the comparison of the ethane conversion rate of Comparative Example 3 and the ethane conversion rate of the embodiment, it can be seen that without using titanium-containing alumina as a carrier, the sulfur resistance activity of the prepared catalyst is greatly reduced.

[0067] In summary, it can be seen that the sulfur-resistant catalytic combustion catalyst of the present invention can ensure that the outlet ethane conversion rate is higher than 90%, indicating that the catalyst has high catalytic activity and sulfur resistance, and fully meets the tail gas emission indicators after VOCs treatment (Petrochemical Industry Pollutant Emission Standard (GB31571-2015) and Petroleum Refining Industry Pollutant Emission Standard (GB31570-2015)). The present invention uses commercially available titanium-containing high-temperature porous activated alumina balls as carriers, adds precious metals platinum and palladium and additives, and then obtains sulfur-resistant catalytic combustion catalysts through impregnation, step-by-step high-temperature roasting, reduction (normal temperature) and other processes, which can save precious metal usage and reduce catalyst costs. The catalyst can be used for the treatment of VOCs tail gas through the catalytic combustion mechanism.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A sulfur-resistant catalytic combustion catalyst, characterized in that: The active carrier is titanium-containing high-temperature porous activated alumina, the active component is precious metal, and the auxiliary agent is non-precious metal. The noble metal is selected from at least one of platinum and palladium; the noble metal accounts for 0.05-1.0% of the total mass of the catalyst; The additive accounts for 0.1-10% of the total mass of the catalyst; The auxiliary agent is one or more of cerium Ce, lanthanum La, copper Cu, zirconium Zr, iron Fe, and chromium Cr; The titanium-containing high-temperature porous active alumina is α-alumina loaded with titanium, and the titanium accounts for 5% of the total mass of the active carrier; The sulfur-resistant catalytic combustion catalyst is prepared by the following steps: S1: dissolving a sponge-state noble metal in aqua regia to obtain a noble metal salt solution, dissolving an auxiliary agent nitrate in an organic solvent to obtain an auxiliary agent solution, and mixing the noble metal salt solution and the auxiliary agent solution to prepare an impregnation solution; S2: adding the impregnation solution prepared in step S1 evenly to the titanium-containing high-temperature porous activated alumina support rolling in the rolling ball pot; S3: The product after impregnation in step S2 is subjected to stepwise high-temperature roasting treatment; S4: cooling the product after the calcination treatment in step S3 to room temperature, then adding hydrazine hydrate with a concentration of 0.1-8 wt% for reduction treatment, the reduction treatment time is 2-8 hours, and after the reduction treatment, washing and drying are performed to obtain a finished catalyst; In step S3, the specific method of the step-by-step high-temperature roasting treatment is: The first stage: directly ignite the product after impregnation in step S2 in a combustion furnace, place the ignited impregnated product in a vibrating screen and burn it with an open flame while vibrating until it is naturally extinguished, and the frequency of the vibrating screen is 10-20Hz; The second stage: high temperature calcination at 400-650℃ for 1.5-4h.

2. A sulfur-resistant catalytic combustion catalyst according to claim 1, characterized in that: The titanium-containing high-temperature porous activated alumina is spherical, and its particle size is 2-6 mm.

3. A method for preparing a sulfur-resistant catalytic combustion catalyst according to claim 1, characterized in that: The following steps are involved: S1: dissolving a sponge-state noble metal in aqua regia to obtain a noble metal salt solution, dissolving an auxiliary agent nitrate in an organic solvent to obtain an auxiliary agent solution, and mixing the noble metal salt solution and the auxiliary agent solution to prepare an impregnation solution; S2: adding the impregnation solution prepared in step S1 evenly to the titanium-containing high-temperature porous activated alumina support rolling in the rolling ball pot; S3: The product after impregnation in step S2 is subjected to stepwise high-temperature roasting treatment; S4: Cool the product after the calcination treatment in step S3 to room temperature, then add hydrazine hydrate with a concentration of 0.1-8wt% for reduction treatment, the reduction treatment time is 2-8h, and after the reduction treatment, it is washed and dried to obtain a finished catalyst.

4. The method for preparing a sulfur-resistant catalytic combustion catalyst according to claim 3, characterized in that: In step S1, the organic solvent is selected from alkanes, alcohols or organic acids.

5. The method for preparing a sulfur-resistant catalytic combustion catalyst according to claim 3, characterized in that: In step S2, the specific method of adding the impregnation liquid prepared in step S1 to the titanium-containing high-temperature porous activated alumina carrier is: adding the titanium-containing high-temperature porous activated alumina carrier to a rolling ball pot, and while the carrier is rolling, adding the impregnation liquid to the rolling ball pot at a rate of 50-200 mL / min.

6. The method for preparing a sulfur-resistant catalytic combustion catalyst according to claim 3, characterized in that: In step S4, after the reduction treatment, washing is performed using a washing liquid, wherein Cl - Less than 10ppm; drying temperature is 120-150℃, drying time is 2-6h.

7. Use of a sulfur-resistant catalytic combustion catalyst as described in any one of claims 1 to 2 or a sulfur-resistant catalytic combustion catalyst prepared by the method for preparing a sulfur-resistant catalytic combustion catalyst as described in any one of claims 3 to 6 in catalytic combustion of VOCs.

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