Platinum-based catalyst for catalytic degradation of short-chain hydrocarbon VOCs and preparation method of platinum-based catalyst

Abstract

The invention discloses a preparation method of a platinum-based catalyst for catalytic degradation of short-chain hydrocarbon VOCs (Volatile Organic Compounds), which comprises the following steps: dissolving a cobalt salt precursor and a zirconium salt precursor in a molar ratio of (8-9): 1 in ultrapure water, adding an organic acid solution while stirring, and ensuring that the molar concentration of the organic acid solution is higher than that of a total metal salt solution; stopping stirring after the solution generates a gelatinous substance, raising the temperature to 70-100 DEG C, and drying overnight; grinding the obtained solid material, and roasting in a muffle furnace; after cooling, weighing a certain mass of product, dissolving in a proper amount of ultrapure water, and stirring to obtain a carrier solution; and dropwise adding an active noble metal platinum precursor salt solution into the carrier solution, fully stirring, drying overnight, roasting a sample in the air at 300-400 DEG C for 3-5 hours, cooling, and introducing a mixed gas of hydrogen and nitrogen for reduction. The catalyst prepared by the method is simple in preparation method, has excellent sulfur tolerance, and can catalytically decompose ethane at the temperature of lower than 300 DEG C.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and in particular relates to a platinum-based catalyst for catalytic degradation of short-chain hydrocarbon VOCs and a preparation method thereof. Background Art

[0002] With the development of society and industrial progress, people's living standards are improving day by day. At the same time, volatile organic compounds (VOCs) emitted by industrial production and automobile exhaust have become the focus of environmental governance and seriously damaged the ecological environment and threatened human health. Ethane, a short-chain hydrocarbon VOCs, is also a saturated alkane with relatively large emissions, and is the focus of many researchers. However, due to its stable chemical properties, the catalytic degradation of ethane is more difficult than other oxygen-containing and unsaturated alkanes, and effective treatment is urgently needed. In addition, in actual working conditions, the presence of sulfur dioxide will have an adverse effect on the life of the catalyst. Therefore, the preparation of a catalyst with good sulfur resistance for efficient catalytic degradation of ethane has very important industrial application value.

[0003] Compared with transition metal oxide catalysts, precious metal catalysts have good catalytic activity and stability, and are more tolerant to sulfur dioxide. They are currently the mainstream direction of catalyst development and application.

[0004] At present, although a lot of work has been done on precious metal catalysts for the catalytic degradation of short-chain hydrocarbon VOCs, the temperature at which existing catalysts completely degrade ethane is generally higher than 300 °C, and low-temperature and efficient degradation is still a difficult problem to be solved. At the same time, the stability and sulfur resistance of the catalyst also need to be further improved. Therefore, it is very necessary to develop a low-temperature and efficient ethane catalyst that is sulfur-resistant and has good low-temperature conversion activity and stability. Summary of the invention

[0005] In order to solve at least one of the above problems, the present invention provides a platinum-based catalyst for catalytic degradation of short-chain hydrocarbon VOCs and a preparation method thereof.

[0006] In order to achieve the above object, the present invention adopts the following technical means: The first aspect of the present invention provides a method for preparing a platinum-based catalyst for catalytic degradation of short-chain hydrocarbon VOCs, comprising the following steps: (1) dissolving a cobalt salt precursor and a zirconium salt precursor in a molar ratio of (8-9):1 in ultrapure water; (2) adding an organic acid solution to the solution of (1) under stirring at a certain temperature; the molar concentration of the organic acid solution is higher than the molar concentration of the total metal salt solution; (3) When the solution in (2) produces a gel-like substance, stop stirring, raise the temperature to 70-100 °C and dry overnight; (4) Grind the material obtained in (3), place it in a muffle furnace, and calcine it in air for 3-5 h; (5) The reaction is cooled to room temperature, a certain mass of the product in (4) is weighed as a carrier, dissolved in an appropriate amount of ultrapure water, and stirred to obtain a carrier solution; (6) dripping an active noble metal platinum precursor salt solution into the solution in (5), stirring thoroughly, and drying overnight; the mass concentration of the noble metal platinum precursor solution dripped in is 0.05-3 wt % of the carrier solution; (7) The material obtained in (6) is calcined in air at 300-400°C for 3-5 hours, cooled, and then reduced by introducing a mixture of hydrogen and nitrogen to obtain the desired platinum-based catalyst.

[0007] Furthermore, the cobalt salt precursor and the zirconium salt precursor are nitrates, acetates or chlorides of cobalt and zirconium metals.

[0008] Furthermore, the organic acid in step (2) is citric acid or oxalic acid.

[0009] Furthermore, the calcination temperature in air in step (4) is in the range of 350-550°C.

[0010] Furthermore, in step (6), the mass concentration of the precious metal platinum precursor solution added dropwise is 0.5-2 wt% of the carrier solution; preferably, the mass concentration of the precious metal platinum precursor solution added dropwise is 1 wt% of the carrier solution.

[0011] Furthermore, in step (7), the mixed gas is a mixed gas of 10 vol % hydrogen and 90 vol % nitrogen, and the flow rate of the mixed gas is 30-50 mL / min.

[0012] Furthermore, in the step (7), the reduction temperature is 250-350°C.

[0013] The second aspect of the present invention provides a catalyst for the catalytic degradation of short-chain hydrocarbon VOCs, which is prepared by the method described in the first aspect.

[0014] The present invention also provides a catalyst prepared by replacing the active precious metal platinum with any one of palladium, ruthenium and iridium, and the catalyst can also catalyze the decomposition of short-chain hydrocarbon VOCs ethane at a temperature below 300°C.

[0015] The third aspect of the present invention provides an application of the catalyst described in the second aspect in low-temperature catalytic degradation of short-chain hydrocarbon VOCs pollution in the atmosphere.

[0016] Furthermore, the short-chain hydrocarbon VOCs is ethane; the low temperature is a temperature below 300°C; further, the low temperature is a temperature below 250°C.

[0017] Beneficial Effects of the Invention Compared with the prior art, the present invention has the following beneficial effects: the present invention provides a catalyst for catalytic degradation of short-chain hydrocarbon VOCs, the short-chain hydrocarbon VOCs is ethane, the catalyst preparation method is simple, in the case of Co: Zr molar ratio of 9: 1, the catalyst can catalytically decompose ethane at a temperature below 300 ° C, after loading with active precious metals, the ethane catalytic temperature of the catalyst is further reduced, and at the same time, the catalyst prepared by the method has excellent sulfur resistance and improved water resistance; in particular, the Co9Zr1 catalyst loaded with 1 wt% Pt can still maintain a conversion rate of more than 80% in a sulfur-containing environment, showing outstanding sulfur resistance. The catalyst fully degrades ethane at low temperatures and has good stability and sulfur resistance, and has broad application prospects in the catalytic degradation of short-chain hydrocarbon VOCs ethane in sulfur-containing flue gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The catalytic effects of the catalysts prepared in Examples 1-3 of the present invention on ethane are compared; Figure 2 The catalytic effects of the catalysts prepared in Examples 1, 4-5 and Comparative Example 1 on ethane are compared; Figure 3 The figure shows the comparison of the catalytic effects of the catalysts prepared in Example 4 and Example 6 of the present invention on ethane; Figure 4 The catalytic effects of the catalysts prepared in Examples 4, 7-8 of the present invention on ethane are compared; Figure 5 The figure shows the comparison of the catalytic effects of the catalysts prepared in Examples 9-12 of the present invention on ethane; Figure 6 The figure shows the comparison of the catalytic effects of the catalysts prepared in Examples 9, 13-14 of the present invention on ethane; Figure 7 The figure shows the comparison of the catalytic effects of the catalysts prepared in Example 9 of the present invention and Comparative Example 2 on ethane; Figure 8 The water resistance test comparison of the catalysts prepared in Example 4 and Example 9 of the present invention is shown; Fig. 9 The sulfur resistance test comparison of the catalysts prepared in Example 4, Example 9, Comparative Example 3 and Comparative Example 4 of the present invention is shown. DETAILED DESCRIPTION

[0019] The following examples are used to demonstrate preferred embodiments of the present invention. It will be appreciated by those skilled in the art that the techniques disclosed in the following examples represent techniques discovered by the inventors that can be used to implement the present invention and therefore can be considered as preferred embodiments of the present invention. However, it will be appreciated by those skilled in the art based on this specification that many modifications may be made to the specific embodiments disclosed herein and still achieve the same or similar results without departing from the spirit or scope of the present invention.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs, and the materials cited herein and those cited by them are incorporated by reference. Those skilled in the art will recognize or will learn through routine experimentation that there are many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the claims.

[0021] The technical solution of the present application is further described in detail below in conjunction with specific implementation methods.

[0022] A method for preparing a platinum-based catalyst for catalytic degradation of short-chain hydrocarbon VOCs comprises the following steps: (1) dissolving a cobalt salt precursor and a zirconium salt precursor in a molar ratio of (8-9):1 in ultrapure water; wherein the cobalt salt precursor and the zirconium salt precursor are nitrates, acetates or chlorides of cobalt and zirconium metals; (2) adding an organic acid solution to the solution of (1) under stirring at a certain temperature; wherein the molar concentration of the organic acid solution is higher than the molar concentration of the total metal salt solution; and the organic acid is citric acid or oxalic acid; (3) When the solution in (2) produces a gel-like substance, stop stirring, raise the temperature to 70-100 °C and dry overnight; (4) Grind the material obtained in (3), place it in a muffle furnace, and calcine it at 350-550 °C for 3-5 h in air; (5) The reaction mixture is cooled to room temperature, a certain amount of the product in step (4) is weighed as a carrier, dissolved in an appropriate amount of ultrapure water and stirred to obtain a carrier solution; (6) dripping a certain concentration of active noble metal platinum precursor salt solution into the solution in (5), stirring for 1 hour, and drying overnight; wherein the mass concentration of the active noble metal platinum precursor solution dripped in is 0.05-3 wt % of the carrier solution; preferably, the mass concentration of the noble metal platinum precursor solution dripped in is 0.5-2 wt % of the carrier solution; (7) The dried sample in (6) is first calcined in air at 300 °C for 3 hours. After cooling, a mixture of 10 vol% hydrogen and 90 vol% nitrogen is introduced for reduction for 1 hour to obtain the desired platinum-based catalyst, wherein the hydrogen flow rate is 30-50 mL / min and the reduction temperature is 250-350 °C.

[0023] In the above method, the active precious metal platinum is replaced by any one of palladium, ruthenium and iridium.

[0024] The present invention also provides a platinum-based catalyst for catalytic degradation of short-chain hydrocarbon VOCs prepared by the method described above.

[0025] The present invention also provides an application of the above-mentioned catalyst in low-temperature catalytic degradation of short-chain hydrocarbon VOCs pollution in the atmosphere; the short-chain hydrocarbon VOCs is ethane; and the low temperature is a temperature below 300°C.

[0026] Example 1 Preparation of Co5Zr5 Catalyst The preparation method is as follows: (1) Dissolve 5 mmol of cobalt nitrate hexahydrate and 5 mmol of zirconium nitrate pentahydrate in 20 mL of ultrapure water and stir evenly; (2) Dissolve 15 mmol of anhydrous citric acid in 15 mL of ultrapure water and stir evenly. Add the citric acid solution dropwise into the solution in (1) at 60 °C while stirring. (3) When the solution in (2) produces a gel-like substance, stop stirring, raise the temperature to 90 °C and dry overnight; (4) The material obtained in (3) was ground, placed in a muffle furnace, and calcined at 350 °C for 4 h under air conditions to obtain the desired Co5Zr5 catalyst.

[0027] Example 2 Preparation of Co5Al5 Catalyst The preparation method is the same as that of Example 1, except that zirconium nitrate pentahydrate is replaced by aluminum nitrate nonahydrate.

[0028] Example 3 Preparation of Co5Fe5 Catalyst The preparation method is the same as that of Example 1, except that zirconium nitrate pentahydrate is replaced by ferric nitrate nonahydrate.

[0029] Example 4 Preparation of Co9Zr1 Catalyst The preparation method is the same as that of Example 1, except that the materials in step (1) are 9 mmol of cobalt nitrate hexahydrate and 1 mmol of zirconium nitrate pentahydrate.

[0030] Example 5 Preparation of Co7Zr3 Catalyst The preparation method is the same as that of Example 4, except that the materials in step (1) are 7 mmol of cobalt nitrate hexahydrate and 3 mmol of zirconium nitrate pentahydrate.

[0031] Example 6 Preparation of Co9Zr1 Catalyst from Oxalic Acid The preparation method is the same as that of Example 4, except that oxalic acid is used instead of citric acid in step (2).

[0032] Example 7 Preparation of Co9Zr1 Catalyst at 450°C The preparation method is the same as that of Example 4, except that the temperature in step (4) is 450°C.

[0033] Example 8 Preparation of Co9Zr1 Catalyst at 550°C The preparation method is the same as that of Example 4, except that the temperature in step (4) is 550°C.

[0034] Example 9 Preparation of Co9Zr1 Catalyst Loaded with 1wt% Pt The preparation method is as follows: (1) Weigh the required mass of the Co9Zr1 catalyst in Example (4) as a carrier, dissolve it in an appropriate amount of ultrapure water and stir evenly; (2) dropping a certain amount of precious metal platinum precursor solution into the solution in (2), stirring for 1 hour, and drying overnight; wherein the mass concentration of the precious metal platinum precursor solution dropped is 1 wt % of the carrier solution; (3) The material obtained in (2) was first calcined in air at 300 °C for 3 hours. After cooling, a mixture of 10 vol% hydrogen and 90 vol% nitrogen was introduced for reduction for 1 hour to obtain a 1wt% Pt-Co9Zr1 catalyst, wherein the flow rate of the mixed gas was 50 mL / min and the reduction temperature was 300 °C.

[0035] Example 10 Preparation of Co9Zr1 Catalyst Loaded with 1 wt% Ir The preparation method is the same as that of Example 9, except that the precious metal platinum precursor solution in step (5) is replaced by a precious metal iridium precursor.

[0036] Example 11 Preparation of Co9Zr1 Catalyst Loaded with 1 wt% Ru The preparation method is the same as that of Example 9, except that the precious metal platinum precursor solution in step (5) is replaced by a precious metal ruthenium precursor.

[0037] Example 12 Preparation of Co9Zr1 Catalyst Loaded with 1 wt% Pd The preparation method is the same as that of Example 9, except that the precious metal platinum precursor solution in step (5) is replaced by a precious metal palladium precursor.

[0038] Example 13 Preparation of Co9Zr1 Catalyst Loaded with 0.5 wt% Pt The preparation method is the same as that of Example 9, except that the concentration of the noble metal platinum precursor solution in step (5) is 0.5 wt % of the carrier solution.

[0039] Example 14 Preparation of Co9Zr1 Catalyst Loaded with 1.5 wt% Pt The preparation method is the same as that of Example 9, except that the concentration of the noble metal platinum precursor solution in step (5) is 1.5 wt % of the carrier solution.

[0040] Comparative Example 1 Preparation of ZrO2 Catalyst The preparation method is the same as that of Example 4, except that the material in step (1) is replaced by 10 mmol of zirconium nitrate pentahydrate.

[0041] Comparative Example 2 Preparation of 1wt% Pt Co9Zr1 Catalyst without Reduction The preparation method is the same as that of Example 9, except that the hydrogen reduction step is not performed.

[0042] Comparative Example 3 Loading 1 wt% Pt-Co3O4 Catalyst The preparation method is the same as that of Example 4, except that the material in step (1) is replaced by 10 mmol of cobalt nitrate hexahydrate.

[0043] Comparative Example 4 Co3O4 Catalyst The preparation method is the same as that of Example 9, except that the material in step (1) is replaced by the Co3O4 catalyst in Comparative Example 3.

[0044] We used the catalysts prepared in Examples 1-14 and Comparative Examples 1-4 to conduct ethane catalytic tests, and the test results are shown in Table 1.

[0045] Table 1 Catalytic effects of catalysts obtained in Examples 1-15 and Comparative Examples 1-4

[0046] (1) Examples 1 to 3 are catalysts prepared by combining Co with different metals, and their effects on ethane conversion are as follows: Figure 1 shown.

[0047] The results show that the catalysts prepared from cobalt and different metals, among which the catalysts prepared from the composite of cobalt and zirconium, have lower catalytic temperatures.

[0048] (2) The catalysts prepared in Example 1, Examples 4-5 and Comparative Example 1 have a comparative effect on ethane conversion. Figure 2 shown.

[0049] The results show that when there is no cobalt in the catalyst, the ethane catalytic efficiency is extremely low. The catalyst obtained by compounding cobalt and zirconium in different proportions significantly improves the ethane catalytic efficiency. Moreover, when cobalt and zirconium are compounded in a ratio of 9:1, the catalyst has a lower catalytic temperature.

[0050] (3) The catalysts prepared in Example 4 and Example 6 have a comparative effect on ethane conversion. Figure 3 shown.

[0051] The results show that different acid solutions are used to prepare Co9Zr1 catalysts, and the acid solutions have little effect on the catalytic performance of Co9Zr1 catalysts.

[0052] (4) The ethane conversion effects of the catalysts prepared in Example 4 and Examples 7-8 are compared as follows: Figure 4 shown.

[0053] The results show that when the Co9Zr1 catalyst is prepared at different temperatures, the catalytic performance of the Co9Zr1 catalyst increases with the increase of temperature, but the catalytic temperature is lower than 300 ℃.

[0054] (5) The catalysts prepared in Examples 9 to 12 have a comparative effect on ethane conversion. Figure 5 shown.

[0055] The results show that when Co9Zr1 catalysts are loaded with different precious metals, the catalytic temperature of the Co9Zr1 catalysts loaded with precious metals is lower than 300 °C, the catalytic temperature of the loaded precious metals Pt and Pd is lower than 250 °C, and the catalytic temperature of the loaded precious metal Pt is lower than that of the precious metal Pd.

[0056] (6) The catalysts prepared in Examples 9 to 13 and 14 have a comparative effect on ethane conversion. Figure 6 shown.

[0057] The results show that the catalytic performance of the precious metal Pt after loading with different loading amounts was compared, and it was found that the catalytic performance of Co9Zr1 loaded with 1wt% Pt was better, with a catalytic temperature of 242 ℃.

[0058] (7) The catalysts prepared in Example 9 and Comparative Example 2 have a comparative effect on ethane conversion. Figure 7 shown.

[0059] The results show that during the process of loading precious metals, the use of hydrogen reduction can further improve the low-temperature catalytic performance of the catalyst.

[0060] (8) The catalysts prepared in Examples 4 and 9 were introduced into 5 vol% H2O during the catalytic conversion of ethane. The catalytic conversion effect was as follows: Figure 8 shown.

[0061] The results show that the water resistance of Co9Zr1 catalyst loaded with 1 wt% Pt is better than that of Co9Zr1 catalyst without Pt.

[0062] (9) The catalysts prepared in Example 4, Example 9, Comparative Example 3 and Comparative Example 4 were introduced into 50 ppm SO2 during the catalytic conversion of ethane. The catalytic conversion effect was as follows: Fig. 9 shown.

[0063] The results show that the addition of zirconium increases the sulfur resistance of the catalyst. Without zirconium, it will quickly deactivate. With the addition of zirconium, the loading of precious metals further improves the sulfur resistance of the catalyst. The Co9Zr1 catalyst loaded with 1 wt% Pt can still maintain a conversion rate of more than 80% in a sulfur-containing environment, showing outstanding sulfur resistance.

[0064] All documents mentioned in the present invention are cited as references in this application, just as each document is cited as references separately. In addition, it should be understood that after reading the above teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined in the present application.

Claims

1. A method for preparing a platinum-based catalyst for catalytic degradation of short-chain hydrocarbon VOCs, characterized in that: The steps include: (1) dissolving a cobalt salt precursor and a zirconium salt precursor in a molar ratio of (8-9):1 in ultrapure water; (2) adding an organic acid solution to the solution of (1) under stirring at a certain temperature; the molar concentration of the organic acid solution is higher than the molar concentration of the total metal salt solution; (3) When the solution in (2) produces a gel-like substance, stop stirring, raise the temperature to 70-100 °C and dry overnight; (4) Grind the material obtained in (3), place it in a muffle furnace, and calcine it in air for 3-5 h; (5) The reaction mixture is cooled to room temperature, a certain amount of the product in step (4) is weighed and dissolved in an appropriate amount of ultrapure water and stirred to obtain a carrier solution; (6) dripping an active noble metal platinum precursor salt solution into the solution in (5), stirring thoroughly and drying overnight; the mass concentration of the active noble metal platinum precursor solution dripped in is 0.05-3 wt % of the carrier solution; (7) The material obtained in (6) is calcined in air at 300-400°C for 3-5 hours, cooled, and then reduced by introducing a mixture of hydrogen and nitrogen to obtain the desired platinum-based catalyst.

2. The method for preparing a platinum-based catalyst for catalytic degradation of short-chain hydrocarbon VOCs according to claim 1, characterized in that: The cobalt salt precursor and the zirconium salt precursor are nitrates, acetates or chlorides of cobalt and zirconium metals.

3. The method for preparing a platinum-based catalyst for catalytic degradation of short-chain hydrocarbon VOCs according to claim 1, characterized in that: In the step (2), the organic acid is citric acid or oxalic acid.

4. The method for preparing a platinum-based catalyst for catalytic degradation of short-chain hydrocarbon VOCs according to claim 1, characterized in that: The temperature range of calcination in air in step (4) is 350-550°C.

5. The method for preparing a platinum-based catalyst for catalytic degradation of short-chain hydrocarbon VOCs according to claim 1, characterized in that: In step (6), the mass concentration of the precious metal platinum precursor solution added dropwise is 0.5-2 wt % of the carrier solution.

6. The method for preparing a platinum-based catalyst for catalytic degradation of short-chain hydrocarbon VOCs according to claim 1, characterized in that: In step (7), the mixed gas is a mixed gas of 10 vol % hydrogen and 90 vol % nitrogen, the flow rate of the mixed gas is 30-50 mL / min, and the reduction temperature is 250-350 °C.

7. A catalyst for catalytic degradation of short-chain hydrocarbon VOCs, characterized in that: The method is prepared by any one of claims 1 to 7.

8. The catalyst for catalytic degradation of short-chain hydrocarbon VOCs according to claim 7, characterized in that: In the method, the active precious metal platinum is replaced by any one of palladium, ruthenium and iridium.

9. Use of the catalyst according to claims 7 and 8 in low-temperature catalytic degradation of short-chain hydrocarbon VOCs pollution in the atmosphere.

10. The use according to claim 9, characterized in that: The short-chain hydrocarbon VOCs is ethane; the low temperature is a temperature below 300°C.

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