A Na + Modified CuO x / CeO2 catalyst, preparation method and application thereof

Abstract

The application discloses a kind of Na + Modified CuO x / CeO2 catalyst and its preparation method and application, belong to functional environmental material technical field.The method will CeO2 suspension liquid, Cu (NO3) 2·3H2O aqueous solution and Na2CO3 aqueous solution are mixed, and are aged centrifugation, filtration and drying, grinding after calcination, drop to room temperature, obtain Na-CuO x / CeO2 catalyst.The application utilizes simple precipitation deposition method to synthesize Na-CuO x / CeO2 catalyst, compared with CO hot catalytic oxidation technology, can quickly oxidize pollutant CO under noble metal and mild conditions, and performance is significantly improved by 6 times;Na-CuO x / CeO2 catalyst is widely used, without noble metal, preparation method is simple, can be large-scale industrialization, reaction condition is mild and pollution-free, with good economic benefit and application prospect.

Description

Technical Field

[0001] This invention belongs to the field of functional environmental materials technology, specifically relating to a Na + Modified CuO x / CeO2 catalysts, their preparation methods, and applications. Background Technology

[0002] Carbon monoxide (CO) is a colorless, odorless, and stable gas. Inhalation weakens the oxygen-carrying capacity of hemoglobin, damages the central nervous system, and seriously endangers human health. In enclosed spaces such as underground parking lots, residential buildings, and ship cabins, CO tends to accumulate easily but is difficult to dissipate, often causing sudden, high-concentration CO pollution. Currently, the elimination of high-concentration CO mainly employs catalytic oxidation. The supported catalysts used include a carrier and an active component. CeO2 is widely used as a carrier due to its excellent redox capabilities, while the active components are mainly noble metals such as Pt and Pd. However, the high amount of noble metals required for catalyst preparation and the need for high-temperature thermal catalytic driving during CO oxidation increasingly highlight the problems of high cost and high energy consumption.

[0003] Non-precious metal catalysts are mainly composed of one or two oxides of Cu, Co, Mn, Ni, Fe, and Ce, among which CuO x CeO2 catalysts have attracted widespread attention due to their good CO oxidation activity and low cost, and are expected to replace noble metal catalysts. Alkali metals can act as structural and electronic promoters in the oxidation of certain noble metal CO, significantly enhancing catalytic activity by influencing the metal coordination environment, electronic state, and metal-support interactions. Currently, most high-concentration CO oxidation removal utilizes thermocatalysis, while photocatalysis, with its low energy consumption and mild conditions, has received little attention.

[0004] Therefore, providing a catalyst that can utilize mild light conditions without adding an additional heat source is of great research significance for achieving rapid removal of high concentrations of CO pollutants. Summary of the Invention

[0005] To address the aforementioned problems in the existing technology, the first technical problem to be solved by the present invention is to provide a Na + Modified CuO x A simple method for preparing / CeO2 catalyst, with mild reaction conditions, no precious metals, and no pollution, using a simple precipitation-deposition method to prepare Na-CuO. x / CeO2 has excellent CO removal properties. The second technical problem this invention aims to solve is to provide a Na... + Modified CuO x / CeO2 catalyst, which can rapidly oxidize pollutant CO under mild conditions without precious metals. The third technical problem to be solved by this invention is to provide a Na-CuO x The application of CeO2 catalyst in the removal of high-concentration CO. The fourth technical problem this invention aims to solve is to provide a method for the rapid low-temperature oxidation of CO, using Na provided in the second technical problem. + Modified CuO x / CeO2 catalyst rapidly photocatalyzes high-concentration CO under full-spectrum illumination from an external light source and at low temperature.

[0006] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0007] A type of Na + Modified CuO x The method for preparing the / CeO2 catalyst involves mixing a CeO2 suspension, an aqueous solution of Cu(NO3)2·3H2O, and an aqueous solution of Na2CO3, aging and centrifuging, filtering and drying, grinding, calcining, and cooling to room temperature to obtain Na-CuO. x / CeO2 catalyst.

[0008] Furthermore, the aging time is 1 hour.

[0009] Furthermore, the calcination is carried out by increasing the temperature to 400°C at a rate of 5°C / min, and the calcination time is 4 hours.

[0010] Furthermore, the CuO x The mass ratio of Na-CuO to CeO2 is 1:100. x / CeO2 catalyst Na + The mass ratio is 0.1%.

[0011] Furthermore, the specific steps are as follows:

[0012] 1) Weigh Ce(NO3)3·6H2O and dissolve it in deionized water. Stir it rapidly on a magnetic stirrer, then add NH3·H2O dropwise until the pH is 10. Then age it for 12 hours, centrifuge and filter it, wash it three times with deionized water, dry it in an oven, grind it into powder, put the powder in a crucible and place it in a muffle furnace. Heat it to 550℃ at 5℃ / min and calcine it for 2 hours. After cooling to room temperature, CeO2 support is obtained.

[0013] 2) Add the CeO2 support obtained in step 1) to deionized water and stir rapidly on a magnetic stirrer to obtain a CeO2 suspension; weigh Cu(NO3)2·3H2O into deionized water and add it dropwise to the CeO2 suspension, then add Na2CO3 aqueous solution dropwise until the pH is 9, age for 1 hour, centrifuge and filter, dry at 75℃ for 12 hours, grind into powder, and then place the powder in a muffle furnace and calcine at 400℃ for 4 hours at a rate of 5℃ / min, then cool to room temperature to obtain Na-CuO. x / CeO2.

[0014] Furthermore, the Na + Modified CuO x / CeO2 catalyst preparation method to prepare Na-CuO x / CeO2 catalyst.

[0015] Furthermore, the Na-CuO x Application of / CeO2 catalyst in the removal of high concentrations of CO.

[0016] A method for rapid low-temperature CO oxidation, the specific steps of which are as follows:

[0017] 1) First, prepare the Na-CuO. x / CeO2 catalyst;

[0018] 2) Add the Na-CuO prepared in step 1) to the catalyst section of the reaction tube in the fixed-bed reactor. x The catalyst is a CeO2 catalyst. A xenon lamp light source is added to irradiate the catalyst part of the reaction tube with full-spectrum light. Then, a mixture of 4% CO + He, 4% O2 + He and 99.999% high-purity He is introduced. After catalysis, the exhaust gas is separated by chromatography and quantified by the equipped FID detector.

[0019] Furthermore, in step 2), the total gas inlet flow rate is 50 mL / min; the CO concentration is 10000 ppm; the catalytic time is 40 min; the rapid heating temperature does not exceed 80℃; and after chromatographic separation, the exhaust gas is quantitatively detected by the equipped FID detector to show that the CO conversion rate reaches 65%.

[0020] Furthermore, in step 2), the total power of the xenon lamp light source is 300W.

[0021] Beneficial effects: Compared with the prior art, the advantages of this invention are:

[0022] (1) This invention utilizes a simple precipitation-deposition method to synthesize Na-CuO. x Compared to the thermal catalytic oxidation of CO, this invention uses a CeO2 catalyst to prepare Na-CuO.x / CeO2 catalysts are widely available, contain no precious metals, have low raw material costs, are simple to prepare, and have mild and pollution-free reaction conditions, thus offering good economic benefits and application prospects.

[0023] (2) Na-CuO prepared by the present invention x / CeO2 catalyst can rapidly oxidize pollutant CO under mild conditions without precious metals, with a 6-fold improvement in performance compared to thermal catalysis. Under mild light conditions, it can rapidly generate oxygen-containing free radicals, promoting the adsorption, activation, and oxidation of more CO molecules, ultimately purifying and eliminating high concentrations of pollutants.

[0024] (3) Na-CuO prepared by the present invention x / CeO2 catalysts exhibit excellent environmental stability and have potential applications in the rapid elimination of high-concentration CO in confined spaces. Attached Figure Description

[0025] Figure 1 The XRD pattern of the sample prepared in this invention;

[0026] Figure 2 The UV-vis DRS spectrum of the sample prepared in this invention;

[0027] Figure 3 The EPR spectrum of the sample prepared in this invention;

[0028] Figure 4 The XPS O1s spectrum of the sample prepared in this invention;

[0029] Figure 5 This is a comparison chart of the CO oxidation performance of the samples prepared in Examples 1 and 2 of this invention with that of CeO2;

[0030] Figure 6 A comparison of the photocatalytic and thermal catalytic CO oxidation performance of the sample prepared in Example 1 of this invention. Detailed Implementation

[0031] The present invention will be further described below with reference to specific embodiments.

[0032] Example 1

[0033] 1. Preparation of CeO2

[0034] Weigh approximately 10g of Ce(NO3)3·6H2O and dissolve it in 200mL of deionized water. Stir rapidly on a magnetic stirrer. Add NH3·H2O dropwise to the solution until the pH reaches 10. After aging the resulting mixture for 12h, centrifuge (10000r / min), filter, and wash three times with deionized water. Place the washed sample in an oven and dry it at 100℃ for 24h. Grind the dried sample into a fine powder using a mortar and pestle. Place the powder in a crucible and calcine it in a muffle furnace at 5℃ / min to 550℃ for 2h. After cooling to room temperature, collect and store the calcined CeO2 support.

[0035] 2. 0.1 Na-CuO x Preparation of / CeO2 catalyst

[0036] Weigh 2g of CeO2 powder into 100mL of deionized water and stir rapidly on a magnetic stirrer; weigh 0.0608g of Cu(NO3)2·3H2O solid into 50mL of deionized water and add it dropwise to the CeO2 suspension; weigh 2.65g of Na2CO3 solid into 50mL of deionized water and add it dropwise to the CeO2 suspension until pH=9; stop stirring and allow the suspension to age at room temperature for 1h; centrifuge and filter the sample and place it in an oven to dry at 75℃ for 12h; grind the dried sample into fine powder using a mortar and pestle; place the powder in a crucible and calcine it in a muffle furnace at 400℃ at a rate of 5℃ / min for 4h; after cooling to room temperature, collect and store the alkali metal Na. + Modified CuO x / CeO2 catalyst, denoted as Na-CuO x / CeO2; ICP-MS analysis showed that Na-CuO x / CeO2 catalyst Na + The mass ratio is 0.1%, denoted as 0.1 Na-CuO. x / CeO2.

[0037] Example 2

[0038] 0.05 Na-CuO x Preparation of / CeO2 catalyst

[0039] Weigh 2g of CeO2 powder (CeO2 prepared in Example 1) into 100mL of deionized water and stir rapidly on a magnetic stirrer; weigh 0.0608g of Cu(NO3)2·3H2O solid into 50mL of deionized water and add it dropwise to the above CeO2 suspension; weigh 2.65g of Na2CO3 solid into 50mL of deionized water and add it dropwise to the above CeO2 suspension until pH=9; stop stirring and allow the suspension to age at room temperature for 1h; wash the centrifuged and filtered sample five times with deionized water, place it in an oven and dry it at 75℃ for 12h; grind the dried sample into fine powder using a mortar and pestle; place the powder in a crucible and calcine it in a muffle furnace at 400℃ at 5℃ / min for 4h, cool it to room temperature, collect and store it to obtain alkali metal Na. + Modified CuO x / CeO2 catalyst, denoted as Na-CuO x / CeO2; ICP-MS analysis showed that Na in the catalyst... + The mass ratio is 0.05%, denoted as 0.05 Na-CuO. x / CeO2.

[0040] Figure 1 The image shows the XRD pattern of the sample prepared in this invention; as can be seen from the figure, the sample is 0.1 Na-CuO. x / CeO2、0.05Na-CuO x A comparison of the XRD images of / CeO2 and CeO2 shows that the crystal structure of the catalysts after Cu loading and Na modification did not change, indicating that the preparation method well maintained the cubic fluorite structure of CeO2.

[0041] Figure 2 The image shows the UV-vis DRS spectrum of the sample prepared in this invention; as can be seen from the figure, the sample contains 0.1 Na-CuO. x / CeO2、0.05 Na-CuO x A comparison of the UV-vis DRS spectra of / CeO2 and CeO2 revealed that 0.1 Na-CuO x / CeO2 ratio 0.05 Na-CuO x / CeO2 and CeO2 have better visible light absorption capabilities, which can generate more photogenerated holes for CO oxidation.

[0042] Figure 3 This is the EPR spectrum of the sample prepared in this invention; as shown in the figure, it represents 0.1 Na-CuO. x / CeO2、0.05Na-CuO x A comparison of the EPR spectra of / CeO2 and CeO2 revealed that 0.1 Na-CuO x / CeO2 corresponds to Cu 2+ The lower content indicates that it produced more low-valent copper species (Cu). + ( ), which can serve as an adsorption site for CO pollutants, adsorbing more CO molecules and facilitating CO oxidation.

[0043] Figure 4 The image shows the XPS O1s spectrum of the sample prepared in this invention; as can be seen from the figure, it represents 0.1 Na-CuO. x / CeO2 and 0.05 Na-CuO x Comparison of XPS O1s spectra of / CeO2 revealed that 0.1 Na-CuO x / CeO2 has more surface-adsorbed oxygen species, which helps to generate highly oxidizing superoxide radicals with photogenerated electrons under light, for the oxidation of CO.

[0044] Example 2

[0045] Na-CuO prepared in Examples 1 and 2 x / CeO2 oxidation of CO test

[0046] CO oxidation reaction was tested using a fixed-bed reactor. The photocatalytic CO oxidation activity was tested by applying full-spectrum illumination to the catalyst section of the reaction tube using a 300W xenon lamp; alternatively, the thermocatalytic CO oxidation activity was tested by a programmed temperature increase at a rate of 5℃ / min without illumination. The exhaust gas was quantified by a FID detector after chromatographic separation. Three feed gases were used: a mixture of 4% CO + He, a mixture of 4% O2 + He, and high-purity He (99.999%). The total inlet flow rate was 50 mL / min, the CO concentration was 10000 ppm, and 200 mg of catalyst was used. The CO conversion rate was calculated using the following formula:

[0047]

[0048] Figure 5 This is a comparison of the CO oxidation performance of the samples prepared in Examples 1 and 2 of this invention with that of CeO2. As shown in the figure, the CO oxidation performance of 0.1 Na-CuO is significantly higher than that of CeO2. x / CeO2、0.05 Na-CuO x Comparison of photocatalytic performance between CeO2 and Na-CuO. The comparison results show that CeO2 has almost no CO oxidation activity; x / CeO2 ratio 0.05 Na-CuO x / CeO2 has better photocatalytic activity, 0.1 Na-CuO x / CeO2 achieved a CO removal rate of 65% after 40 minutes of light irradiation (the light caused the catalyst surface temperature to rise rapidly to 75°C).

[0049] Figure 6 This is a comparison of the photocatalytic and thermal catalytic CO oxidation performance of the sample prepared in Example 1 of this invention, further highlighting the advantages of this technology in removing CO pollutants. We heated the reaction tube to 75°C. As shown in the figure, 0.1 Na-CuO... x The thermal catalytic removal efficiency of CO pollutants by / CeO2 is only 10%. Therefore, the synthesized Na... + Modified CuO x The / CeO2 catalyst can achieve rapid removal of high-concentration CO pollutants under mild, safe, and simple light irradiation conditions. Compared with thermal catalytic reactions, its purification efficiency is more than 6 times higher, mainly due to Na... + and CuO x The modification of species increases the content of low-valence Cu species and active oxygen species on the CeO2 surface, which helps to adsorb a large amount of CO pollutants and generate strong oxidizing oxygen species under light, thereby achieving rapid oxidative removal of high-concentration CO pollutants under mild conditions.

Claims

1. A method for rapid low-temperature oxidation of CO, characterized in that, The specific steps are as follows: 1) First prepare Na + Modified CuO x The method for obtaining the / CeO2 catalyst is as follows: A CeO2 suspension, an aqueous solution of Cu(NO3)2·3H2O, and an aqueous solution of Na2CO3 are mixed, aged, centrifuged, filtered, dried, ground, calcined, and cooled to room temperature to obtain Na-CuO. x / CeO2 catalyst; wherein CuO x Cu species include Cu 2+ Cu + ; 2) Add the Na-CuO prepared in step 1) to the catalyst section of the reaction tube in the fixed-bed reactor. x The catalyst is CeO2, and a xenon lamp light source is added to apply full-spectrum illumination to the catalyst part of the reaction tube. Then, a mixture of 4% CO+He, 4% O2+He and 99.999% high-purity He is introduced. After catalysis, the exhaust gas is separated by chromatography and quantified by the equipped FID detector.

2. The method for rapid low-temperature oxidation of CO according to claim 1, characterized in that, In step 2), the total gas inlet flow rate is 50 mL / min; the CO concentration is 10000 ppm; the catalytic time is 40 min; the surface temperature of the catalyst after being irradiated by the light source rises rapidly to no more than 80°C; after the exhaust gas is separated by chromatography, the CO conversion rate is quantitatively detected by the equipped FID detector to reach 65%.

3. The method for rapid low-temperature oxidation of CO according to claim 1, characterized in that, In step 2), the total power of the xenon lamp light source is 300W.

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