A Pt / a-CO / TiO2 catalyst with a C–O–M dual interface and its application in VOCs purification

Abstract

A Pt / a-CO / TiO2 catalyst with a C–O–M dual interface and its application in VOCs purification belong to the fields of catalytic chemistry and environmental chemistry. By precisely controlling the structure and thickness of the amorphous oxygen-containing carbon layer (a-CO) on the TiO2 surface, a C–O–M (M = Pt and Ti) dual interface structure was successfully constructed, significantly improving the photothermal synergistic catalytic elimination efficiency of typical VOCs (including but not limited to pentane, heptane, octane, ethanol, hexanal, ethyl acetate, or toluene). The innovative design of the Pt / a-CO / TiO2 catalyst not only demonstrates its universal applicability for the purification of a variety of VOCs, but also opens up new ideas for the further application of photothermal catalytic technology in the field of VOCs purification. It has good application prospects in the field of air pollution control and has the potential to promote the development of environmental chemistry and catalytic chemistry technologies.

Description

Technical Field

[0001] This invention relates to a method for preparing a novel catalyst with a C–O–M (M = Pt and Ti) dual-functional interface, suitable for efficient photothermal catalytic elimination of typical volatile organic compounds (VOCs). The catalyst's preparation technology and application lie in the fields of catalytic chemistry and environmental chemistry, demonstrating significant innovation and application value. Background Art

[0002] Volatile organic compounds (VOCs) are the main pollutants of ozone (O3) and fine particulate matter (PM 2.5 ) is one of the key precursors formed. The VOCs in catering oil fumes are complex, covering alkanes, alkenes, aromatic hydrocarbons, aldehydes, ketones, acid esters, alcohols and polycyclic aromatic hydrocarbons. VOCs treatment technologies are mainly divided into two categories: one is physical methods, such as absorption, membrane separation and condensation; the other is chemical or biological technology, covering biodegradation, thermal incineration, photocatalysis and catalytic combustion. Catalytic oxidation technology is widely used because of its high efficiency and low secondary pollution characteristics. Photothermal catalytic technology makes full use of sunlight by combining light energy and heat energy. It has the advantages of mild conditions and high selectivity, and is more suitable for the VOCs emission control needs of urban catering industry.

[0003] Photothermal synergistic catalytic oxidation technology effectively combines the advantages of thermal catalysis and photocatalysis, aiming to solve the high energy consumption problem in traditional thermal catalysis and the limitation of insufficient photocatalytic efficiency. In the elimination of VOCs in restaurant fumes, the development of efficient photothermal synergistic catalysts is key. Studies have shown that by combining the advantages of precious metals (such as Pt, Pd, Ru, etc.) for the efficient adsorption and activation of VOCs, and the efficient photogenerated carrier excitation effect generated by materials such as metal oxides (such as TiO2, Fe2O3, etc.) under light, composite nanostructures have been reported to show relatively excellent photothermal catalytic combustion or selective oxidation performance. Zhang et al. (LL Kang, et al., Angew. Chem. Int. Ed. 2020, 59, 12909-12916.) studied the photothermal oxidation of propane over Pt / TiO2-WO3 catalysts. They found that the combined effects of light and heat inhibited oxygen poisoning of the Pt catalyst, accelerating C–H bond activation on the Pt surface. The reaction temperature for 70% propane conversion decreased from 324°C to 90°C, and the apparent activation energy decreased from 130 to 11 kJ / mol. Jia et al. (GH Li, et al., J. Hazard. Mater. 2023, 449, 131041.) used MIL-125 as a precursor and prepared a Pt / Mn-TiO2 catalyst with abundant oxygen vacancies by high-temperature calcination. Under the combined effects of light and heat at 180°C, toluene conversion reached 80%, significantly exceeding the 50% achieved under thermal catalysis. Furthermore, the synergistic effects of light and heat significantly improved CO2 selectivity.

[0004] Although existing composite nanostructured catalysts have made progress in the field of photothermal catalysis, they still face technical challenges such as weak interaction between precious metals and supports, low electron-hole pair separation efficiency, and slow charge transfer process. These problems limit the effective utilization of reactants and molecular oxygen at adsorption sites, affecting the overall performance of the catalyst. In response to the above challenges, the present invention uses a simple hydrothermal method and ethylene glycol reduction method to prepare a Pt / a-CO / TiO2 catalyst (a-CO is the abbreviation of amorphous oxygen-containing carbon layer, amorphous carbon oxide) with a C–O–M (M = Pt and Ti) double interface, which significantly reduces the temperature of photothermal elimination of typical VOCs (including but not limited to pentane, heptane, octane, ethanol, hexanal, ethyl acetate or toluene) in restaurant oil smoke. At 140 ° C and 200 mW cm -2 Under full solar spectrum illumination, the n-heptane conversion rate over Pt / a-CO / TiO2 was 8.7 times and 61.8 times that of Pt / TiO2 and Pt / a-CO, respectively. The photothermal conversion rate over Pt / a-CO / TiO2 was 14.0 and 11.7 times that of its photocatalytic and thermal catalytic counterparts, respectively. After 40 hours of (water) thermal stability testing, the Pt / a-CO / TiO2 catalyst maintained efficient photothermal catalytic activity, demonstrating excellent long-term stability.

[0005] According to existing literature and patent search results, there are no reports on Pt / a-CO / TiO2 catalysts with a C–O–M (M = Pt and Ti) dual-interface structure, particularly for applications in the photothermal catalytic removal of typical VOCs (including but not limited to pentane, heptane, octane, ethanol, hexanal, ethyl acetate, or toluene). This present invention proposes for the first time an innovative, controllable preparation strategy for Pt / a-CO / TiO2 catalysts, which significantly improves the photothermal catalytic efficiency of VOCs. This structural innovation opens new possibilities for the application of photothermal catalytic technology in VOC purification and is expected to promote technological advancement in related fields. Summary of the Invention

[0006] The core objective of this invention is to develop a Pt / a-CO / TiO2 catalyst with a C–O–M (M = Pt and Ti) dual-interface structure. By optimizing interfacial interactions, this catalyst significantly improves the adsorption and activation of reactants and the utilization of photogenerated electrons, thereby achieving efficient photothermal catalytic elimination of typical VOCs.

[0007] A Pt / a-CO / TiO2 catalyst with a C–O–M dual interface and its application in VOCs purification, the present invention specifically comprises the following steps:

[0008] The specific steps of catalyst synthesis are as follows:

[0009] (1) Preparation of Pt colloidal suspension

[0010] Slowly add 20 mL of a 0.26 mol / L NaOH solution in ethylene glycol to a 20 mL, 20 g / L H₂PtCl₆·6H₂O solution in ethylene glycol. After stirring for 30 minutes, heat the mixture to 160°C in an oil bath and continue stirring under N₂ atmosphere for 3 hours to obtain a dark brown Pt colloidal suspension (preferably at a concentration of 3.7 g / L). (2) Preparation of a-CO / TiO2, i.e., C–O–Ti interface construction; TiO2 was dissolved in water and ultrasonicated for 1 h until uniformly dispersed; glucose was added to the solution, stirred for 30 min, and then transferred to a Teflon-lined stainless steel autoclave and maintained at 180°C for 3 h; the obtained product was washed several times with deionized water and ethanol, respectively, followed by centrifugation and drying; finally, it was calcined at 500°C for 2 h in a nitrogen atmosphere with a heating rate of 2°C / min to obtain a-CO / TiO2; 2-8 g of glucose was obtained for every 0.5 g of TiO2;

[0011] (3) Preparation of Pt / a-CO / TiO2, i.e., construction of a C–O–Pt interface; the a-CO / TiO2 prepared in step (2) is dispersed in ethanol, and after uniform dispersion, the platinum colloidal suspension obtained in step (1) is added, and the suspension is bubbled and stirred for 6 h under a stream of N2, the mixture is filtered, and washed with deionized water and ethanol several times, and dried, for example, at 80°C for 12 h, and then heated from room temperature to 500°C at a rate of 2°C / min in a N2 atmosphere and maintained for 1 h to obtain a Pt / a-CO / TiO2 catalyst; the amount of Pt used is such that Pt accounts for 0.1-0.5 wt% of the total mass of the catalyst.

[0012] Catalyst performance evaluation:

[0013] VOCs (including but not limited to pentane, heptane, octane, ethanol, hexanal, ethyl acetate and / or toluene) were selected as probe molecules for the evaluation of relevant catalyst performance. The gas composition was 300ppm VOCs + 20vol% O2 + N2 (balance gas) with a space velocity of 20,000mL / (gh). On the Pt / a-CO / TiO2 catalyst, photothermal catalysis (where light corresponds to 200mW cm -2 The reaction temperature (T) required for the heptane conversion rate to reach 50% and 90% under full solar spectrum illumination 50％ and T 90％ ) were 106 and 128 °C, respectively, which were lower than the thermal catalytic performance under the same test atmosphere (169 and 185 °C). Pt / a-CO / TiO2 catalyst has excellent catalytic activity at 140 °C and 200 mW cm-2 Under full solar spectrum illumination, the conversion rate of heptane catalyzed by Pt / a-CO / TiO2 was 8.7 times and 61.8 times that of Pt / TiO2 and Pt / a-CO, respectively. The photothermal catalytic conversion rate of heptane catalyzed by Pt / a-CO / TiO2 was 8.7 times and 61.8 times that of Pt / TiO2 and Pt / a-CO, respectively. -2 The photocatalytic activity of the Pt / a-CO / TiO2 catalyst was 14.0 and 11.7 times that of the thermal catalytic activity under full solar spectrum illumination and 140°C in the dark. The Pt / a-CO / TiO2 catalyst maintained high photocatalytic activity after 40 hours of thermal stability testing (in water).

[0014] The crystal structure and surface morphology of the catalyst were characterized in detail using X-ray diffraction (XRD), high-resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), and energy-dispersive X-ray spectroscopy (EDX). The chemical states and coordination environments of C, Pt, O, and Ti in the sample were analyzed using synchrotron X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). The catalyst's performance in photothermal catalytic removal of volatile organic compounds (VOCs) from cooking oil fumes was evaluated using a Shimadzu GC-2014C gas chromatograph (GC).

[0015] The present invention relates to a method for preparing a catalyst and its application. The method is simple in process and constructs a dual-advantage interface structure by precisely controlling the structure and thickness of the amorphous oxygen-containing carbon layer (a-CO) on the surface of TiO2, thereby achieving efficient photothermal synergistic elimination of typical VOCs. The innovative design strategy of the Pt / a-CO / TiO2 catalyst and its universal applicability to the purification of various types of VOCs are all demonstrated. In response to the high energy consumption problem commonly found in the VOCs purification process, the present invention adopts a photothermal synergistic catalytic purification strategy. This strategy significantly reduces the energy consumption in the VOCs purification process by effectively utilizing solar energy, while reducing dependence on fossil fuels and helping to reduce pollutant emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The XRD patterns of each catalyst are shown to characterize its crystal structure.

[0017] Figure 2 The HAADF-STEM image and EDX element distribution map of the Pt / a-CO / TiO2 catalyst are provided. Figure 3 The XANES and EXAFS spectra of the Pt / a-CO / TiO2 catalyst (C, Pt, O, and Ti elements, respectively) are depicted to analyze its chemical state and coordination environment.

[0018] Figure 4The comparison of reaction rates of the catalyst and its control sample in catalytic typical VOCs oxidation tests is shown.

[0019] Figure 5 A comparison chart of catalyst (water) thermal stability test results is shown. DETAILED DESCRIPTION

[0020] To further illustrate the present invention, the following examples describe the preparation of the catalyst material and its application effects in detail, supplemented by accompanying figures. These examples are intended to illustrate specific embodiments of the catalyst material of the present invention and its effects in practical applications. However, it should be understood that these examples are not intended to limit the scope of the present invention.

[0021] Example 1

[0022] (1) Preparation of Pt / a-CO / TiO2 catalyst: 0.5 g of TiO2 was dissolved in 50 ml of water and uniformly dispersed by ultrasonic treatment for 1 h. 4.0 g of glucose was added to the solution, stirred for 30 min, and then transferred to a 100 mL Teflon-lined stainless steel autoclave and maintained at 180°C for 3 h. The obtained product was washed several times with deionized water and ethanol, then centrifuged and dried. Finally, a-CO / TiO2 was obtained by calcination at 500°C for 2 h under N2 atmosphere with a heating rate of 2°C / min. 1.0 g of a-CO / TiO2 carrier was dissolved in 50 ml of ethanol and uniformly dispersed. 810 μL of platinum colloidal suspension (3.7 g / L) was added and the suspension was bubbled and stirred for 6 h under N2 flow. The mixture was filtered, washed several times with deionized water and ethanol, and dried at 80°C for 12 h. In a N2 atmosphere, the temperature was raised from room temperature to 500℃ at a heating rate of 2℃ / min and maintained for 1h to prepare Pt / a-CO / TiO2 catalyst.

[0023] (2) Preparation of Pt / TiO2 Catalyst: 1.0 g of TiO2 was dissolved in 50 ml of ethanol and uniformly dispersed. 810 μL of a platinum colloidal suspension (3.7 g / L) was then added. The suspension was stirred under a stream of N2 for 6 h. The mixture was filtered, washed with deionized water and ethanol several times, and dried at 80°C for 12 h. The temperature was then increased from room temperature to 500°C in an N2 atmosphere at a rate of 2°C / min and maintained for 1 h to prepare the Pt / TiO2 catalyst.

[0024] (3) 4.0 g of glucose was dissolved in 50 mL of deionized water, stirred for 30 min, and then transferred to a 100 mL Teflon-lined stainless steel autoclave and maintained at 180 °C for 3 h. The obtained product was washed several times with deionized water and ethanol, then centrifuged and dried. Finally, it was calcined at 500 °C for 2 h under N2 atmosphere at a heating rate of 2 °C / min to obtain a-CO. 1.0 g of a-CO carrier was dissolved in 50 mL of ethanol, uniformly dispersed, and then 810 μL of platinum colloidal suspension (3.7 g / L) was added. The suspension was bubbled and stirred for 6 h under N2 flow. The mixture was filtered and washed several times with deionized water and ethanol, and dried at 80 °C for 12 h. The Pt / a-CO catalyst was prepared by heating from room temperature to 500 °C at a heating rate of 2 °C / min in N2 atmosphere and maintaining for 1 h.

[0025] (4) The Pt / a-CO / TiO2 catalyst was used for the photocatalytic oxidation of typical VOCs (including but not limited to pentane, heptane, octane, ethanol, hexanal, ethyl acetate and / or toluene). The photocatalytic reaction was carried out in a fixed bed reactor, which was a tubular structure with a length of 12 mm, a width of 12 mm and a height of 1 mm. The reactor was operated at atmospheric pressure and the catalyst was irradiated through a small window on the side of the furnace. The simulated sunlight was provided by a 300 W xenon lamp (PLS-SXE300D / 300DUV, Perfectlight, Beijing; wavelength range 320-2500 nm). The actual light power density of the xenon lamp was measured by an optical power meter (PM100D+S425C, Thorlabs). Approximately 100 mg of the catalyst (particle size 40–60 mesh) was mixed evenly with quartz sand and loaded into the reactor. The typical reaction gas mixture consists of VOCs (300 ppm, pentane, heptane, octane, ethanol, hexanal, ethyl acetate, or toluene), 20 vol% O2, and N2 (balance), with a total flow rate of 33.3 mL / min (corresponding to GHSV = 20,000 mL / (gh)). 200 mW / cm -2 Under the conditions of Pt / a-CO / TiO2 photothermal catalysis, the T 50％ and T 90％ At 106 and 128 ° C. At 140 ° C (200mW / cm -2 The conversion rates of VOCs (300 ppm, pentane, heptane, octane, ethanol, hexanal, ethyl acetate or toluene) catalyzed by Pt / a-CO / TiO2 were 3.2, 21.0, 7.4, 20.8, 21.0, 9.9 and 17.8 μmol / (g Pts), and its conversion rate of VOCs is higher than that of traditional Pt / TiO2 catalysts. The conversion rates of heptane catalyzed by Pt / a-CO / TiO2 under photocatalytic (light, 30℃) and thermal catalytic (dark, 140℃) conditions are 1.8 and 1.5 μmol / (g, respectively). Pt s), that is, the photothermal catalytic conversion rate of heptane catalyzed by Pt / a-CO / TiO2 was 14.0 and 11.7 times that of its photocatalytic and thermal catalytic performance, respectively. The catalyst showed excellent photothermal synergistic catalytic performance; the photothermal oxidation rate of heptane catalyzed by Pt / a-CO / TiO2 (21.0 μmol / (g Pt s)) are Pt / TiO2(2.4μmol / (g Pt s)) and Pt / a-CO(0.34μmol / (g Pt s)) by 8.8 times and 61.8 times, and the C–O–M (M=Pt and Ti) dual interface structure significantly improved the VOCs conversion.

[0026] (5) In the thermal activity test of the Pt / a-CO / TiO2 catalyst in the presence of water (300 ppm heptane, 20 vol% O2 and N2 water vapor with a volume fraction of 10 and 20 vol%, and a temperature of 130°C and 180°C) for up to 40 h, the performance was not significantly weakened compared with the fresh sample and the catalysis was stable (the heptane conversion rate dropped from 92% to about 83% after the introduction of water vapor and remained stable (the heptane conversion rate on the traditional Pt / TiO2 catalyst decreased by more than 20%). After the water vapor was cut off, the heptane conversion rate increased and even exceeded the performance before the water was introduced (reaching 98%)).

Claims

1. A compound with C–O– M The preparation method of a double-interface Pt / a-CO / TiO2 catalyst is characterized in that: The catalyst has C–O– M Double-interface Pt / a-CO / TiO2 catalyst, a-CO is the abbreviation of amorphous oxygen-containing carbon layer, M = Pt and Ti, comprising the following steps: (1) Preparation of Pt colloidal suspension; (2) Preparation of a-CO / TiO2, i.e., C–O–Ti interface construction; TiO2 was dissolved in water and ultrasonicated for 1 h until uniformly dispersed; glucose was added to the solution, stirred for 30 min, and then transferred to a Teflon-lined stainless steel autoclave and maintained at 180 °C for 3 h; the obtained product was washed several times with deionized water and ethanol, respectively, and then centrifuged and dried; finally, it was calcined at 500 °C for 2 h in a nitrogen atmosphere with a heating rate of 2 °C / min to obtain a-CO / TiO2; 2−8 g of glucose were obtained for every 0.5 g of TiO2; (3) Preparation of Pt / a-CO / TiO2, i.e., construction of the C–O–Pt interface; the a-CO / TiO2 prepared in step (2) was dispersed in ethanol. After uniform dispersion, the Pt colloidal suspension obtained in step (1) was added. The suspension was bubbled and stirred for 6 h under a nitrogen gas flow. The mixture was filtered and washed with deionized water and ethanol several times, dried at 80 °C for 12 h, and then heated from room temperature to 500 °C in a nitrogen atmosphere at a rate of 2 °C / min and maintained for 1 h to obtain a Pt / a-CO / TiO2 catalyst; the amount of Pt used was such that Pt accounted for 0.1−0.5 wt% of the total mass of the catalyst.

2. The preparation method according to claim 1, characterized in that: (1) Preparation of Pt colloidal suspension: 20 mL of NaOH solution dissolved in ethylene glycol was slowly added dropwise to the ethylene glycol solution of H2PtCl6∙6H2O. After stirring for 30 min, the mixture was heated to 160°C in an oil bath and stirred for 3 h under N2 atmosphere to obtain a dark brown Pt colloidal suspension with a concentration of 3.7 g / L.

3. The C-O- M Double-interface Pt / a-CO / TiO2 catalyst.

4. The C-O- M The application of double-interface Pt / a-CO / TiO2 catalyst is characterized by: Used for photothermal catalytic elimination of volatile organic compounds (VOCs).

5. The use according to claim 4, characterized in that The light is full-spectrum simulated sunlight.

6. The use according to claim 4 or 5, characterized in that The VOCs are pentane, heptane, octane, ethanol, hexanal, ethyl acetate and / or toluene.

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