CN106807451B - A kind of flexible platinum-formaldehyde room temperature oxidation catalyst and preparation method thereof - Google Patents

Abstract

The invention relates to a flexible Pt formaldehyde room temperature oxidation catalyst and a preparation method thereof, in particular to a Pt/TiO ₂ /cotton fiber flexible composite formaldehyde room temperature oxidation catalyst and a preparation method thereof. The catalyst includes degreased cotton fiber carrier, nano- _TiO2 surface coating and Pt active component dispersed on the surface of _TiO2 coating, wherein the Pt active component exists in the form of zero valence, the particle size range is 1‑10 nm, and the loading capacity is 0.05‑2 wt%. The Pt/ _TiO2 /cotton fiber composite formaldehyde oxidation catalyst at room temperature provided by the invention has the characteristics of hierarchical mesopore-macropore structure, light weight and flexibility, and the combination between Pt and _TiO2 coating and carrier cotton fiber is firm, and the active component Elemental Pt has good dispersion and small particle size on the surface of TiO ₂ coating. It can efficiently catalyze and decompose formaldehyde at room temperature. The amount of precious metal Pt is small and the gas resistance is small, which is suitable for use in various air purifiers.

Description

A kind of flexible platinum-formaldehyde room temperature oxidation catalyst and preparation method thereof

technical field

The invention relates to a Pt/TiO ₂ /cotton fiber composite formaldehyde oxidation catalyst at room temperature, which belongs to the field of indoor air purification.

Background technique

Formaldehyde is one of the most important pollutants in indoor air and has great toxicity. At present, eliminating indoor formaldehyde pollution has become a hot research topic in the field of environmental governance. Among the existing formaldehyde removal methods, the room temperature catalytic oxidation method is better than other methods (adsorption method, absorption method, anion oxidation method, ozone catalytic oxidation method, biological filtration/plant purification method, low temperature plasma method and photocatalytic oxidation method, etc.) It has unique advantages, it can be carried out under normal temperature and pressure, high formaldehyde removal efficiency, simple equipment, long life and other advantages, it is the most potential formaldehyde removal technology. In recent years, this technology has made continuous progress and breakthroughs in the application research of indoor air purification, such as Chinese invention patents CN200410047973.7, CN200410102837.3, CN200910215887.5, CN200910098634.4, CN200910047376.7, CN200610011663.9, CN200710192, CN2007101927 .0 and CN201410015867.4. In the patent CN200410047973.7, the metal oxide carrier is prepared first, then soaked in the solution of the noble metal component and then evaporated. However, the state of the active component of the catalyst is not indicated, and the activity is also low. As we all know, in order to obtain high and stable formaldehyde catalytic oxidation activity, the catalyst must have good dispersion, small particle size and appropriate valence state. And most patents such as CN200410102837.3, CN200910215887.5, CN200910098634.4, CN200910047376.7, CN200610011663.9 and CN200710121423.9 in the catalyst preparation method described in the sample metal may exist in the form of oxides, and Poor dispersion will affect the improvement of activity; and if you want to obtain 0-valent noble metals, you need a high-temperature _H2 reduction process, which complicates the process and increases the cost accordingly. Patent CN201210389227.0 reports a preparation method of formaldehyde room temperature oxidation catalyst, which uses porous inorganic oxide as carrier, sodium borohydride as reducing agent, soluble metal hydroxide as additive, through impregnation-room temperature reduction-deposition It is prepared by reacting with precious metal precursors. This method realizes the catalytic oxidation of the catalyst at room temperature and also exhibits high catalytic activity. However, from a practical point of view, the catalysts prepared in the above published patents are mostly made of ordinary porous inorganic nanoparticles (such as titanium dioxide, aluminum oxide, molecular sieves, cerium oxide and silicon oxide, etc.) as carriers. Filled purification equipment needs to be pressed into tablets or further loaded on other bulky carriers before it can be used, which will complicate the process, and there are problems such as reduced catalytic activity, large air resistance and easy fall off of the catalyst. In order to overcome the above defects, the patent CN201410015867.4 uses TiO ₂ prepared by electrospinning as a carrier, and prepares a supported noble metal/TiO ₂ composite catalyst by impregnation-room temperature reduction-deposition method. The newly prepared catalyst does not need to be re-loaded, and has High catalytic activity and small air resistance, but the catalyst is brittle because it is based on inorganic _TiO2 nanofibers, and the brittleness increases with the decrease of fiber diameter, which will cause It will be broken continuously, and the original fiber structure will be gradually destroyed, so that the air resistance will gradually increase. Moreover, in the subsequent process of noble metal loading, a process of heating and evaporating is required to remove residual chloride ions (from the noble metal precursor), so the process is still relatively complicated. At the same time, there are still some problems in the preparation of TiO ₂ fibers by electrospinning, such as high cost, high equipment requirements, and certain difficulties in large-scale production.

Contents of the invention

The technical problem to be solved by the present invention is to provide a flexible Pt composite formaldehyde room temperature oxidation catalyst and its preparation method in view of the deficiencies in the prior art, specifically a Pt/TiO ₂ /cotton fiber composite formaldehyde room temperature oxidation catalyst and its preparation method .

In order to solve the problems of the technologies described above, the technical scheme adopted in the present invention is as follows:

A Pt/ _TiO2 /cotton fiber composite formaldehyde oxidation catalyst at room temperature, comprising cotton fiber carrier, _TiO2 Surface coating and the Pt active component dispersed on the _TiO2 coating surface, described cotton fiber carrier is degreased cotton fiber, It itself has a hierarchical macropore-medium pore structure, the TiO ₂ coating is a nano-titanium dioxide coating, the Pt exists in a zero-valent form, and the particle size ranges from 1 to 10 nm.

In the above scheme, the platinum loading is 0.05-2wt%, and the optimal loading is 0.25-0.75wt%.

The preparation method of the above-mentioned Pt/ _TiO2 /cotton fiber composite formaldehyde oxidation catalyst at room temperature, first hydrolyzes the titanium alkoxide in an acidic aqueous solution, and obtains a stable _TiO2 sol after stirring; then uniformly coats the nano- _TiO2 by the dipping method on the surface of cotton fiber, separated and dried to obtain _{TiO 2} /cotton fiber composite base material; - Reduction-deposition method loads the active component Pt on the surface of TiO ₂ coating, and finally washes with alkali and water several times to remove residual chloride ions on the surface to obtain Pt/TiO ₂ /cotton fiber composite formaldehyde oxidation catalyst at room temperature.

According to the above scheme, the preparation method of the Pt/TiO ₂ /cotton fiber composite formaldehyde room temperature oxidation catalyst is to dissolve titanium alkoxide in absolute ethanol, add acetylacetone, stir to form a transparent solution, and then add dropwise to pH= 2-3 days in an acidic aqueous solution containing PVA, stir for 4-8 days to obtain a stable sol, then uniformly coat _TiO2 nanoparticles on the surface of cotton fibers by dipping method, separate and dry to obtain a _TiO2 /cotton fiber composite substrate Material, wherein the molar ratio of water, absolute ethanol, acetylacetone and titanium alkoxide is =100:2～4:0.1～0.5:0.1～0.5; the content of PVA in acidic water is 0.01～0.1%; As a precursor, complexing agent and reducing agent are added, the active component Pt is loaded on the surface of _TiO2 coating by dipping-reduction-deposition method, and finally the residual chloride ions on the surface are removed by alkali washing and water washing for several times, and after drying A Pt/TiO ₂ /cotton fiber composite formaldehyde oxidation catalyst at room temperature was obtained.

According to the above scheme, the titanium alkoxide is one or a mixture of tetraisopropyl titanate and tetrabutyl titanate; the acidic substance is nitric acid, sulfuric acid or a mixture of the two; the The complexing agent is trisodium citrate or disodium ethylenediaminetetraacetic acid (EDTA) or a mixture of the two; the reducing agent is potassium borohydride, sodium borohydride or a mixture of the two. The alkali washing is washing with any aqueous solution of NaOH, KOH and ammonia or a mixture of two or three of them.

The impregnation method is to soak cotton fiber in TiO ₂ sol, the soaking time is 5-10min, wherein the mass ratio of cotton and TiO ₂ is 1:2-3; the separation is screen separation; drying conditions: First dry at 50-70°C for 3-10 minutes, then at 110-120°C for 20-40 minutes, the above coating process can be repeated 1-2 times, the last drying temperature is 60-110°C, dry Time 4 ~ 12h.

The impregnation-reduction-deposition method is as follows: the TiO ₂ /cotton fiber composite material is dispersed in a mixed solution containing chloroplatinic acid and a complexing agent and soaked for 5-10 minutes, wherein chloroplatinic acid accounts for 10% of the TiO ₂ in terms of Pt content. / 0.05～2wt% of the cotton fiber composite base material, then add the alkaline solution of reducing agent (pH between 8.0～10.0), the precious metal is reduced into metal nanoparticles, wherein chloroplatinic acid, the mole of complexing agent and reducing agent The ratio is 1:2:5~30, continue stirring for 5~10min, then separate the composite fiber deposited with Pt from the solution, and dry at 60~110℃ for 4~24h to obtain Pt/TiO ₂ /cotton fiber composite formaldehyde oxidation at room temperature catalyst.

The Pt/TiO ₂ /cotton fiber composite formaldehyde oxidation catalyst at room temperature provided by the present invention has the characteristics of hierarchical meso-macropore structure, light weight and flexibility, and can avoid the need for tableting or further processing of traditional catalysts in filled purification equipment. The problem of large air resistance and easy falling off of the catalyst caused by loading it on other bulky carriers can also avoid the problem of easy breakage of inorganic nanofibers during use. The combination between Pt, TiO ₂ coating and carrier cotton fiber is firm, the active component Pt has good dispersion on the surface of TiO ₂ coating, the particle size is between 1 and 10nm, it can efficiently catalyze and decompose formaldehyde at room temperature, and the amount of precious metal is small, suitable for Used in various air purifiers.

Compared with the prior art, the present invention has the following beneficial effects:

(1) The catalyst of the present invention is an organic-inorganic composite structure, Pt and TiO ₂ Coatings and carrier cotton fibers are firmly combined, and have a hierarchical mesopore-macropore structure, and the active component Pt component is dispersible in the carrier Good, the particle size is between 1-10nm and 0 valence, it can efficiently catalyze the oxidation of formaldehyde at room temperature, the air resistance is small, and the amount of precious metal Pt is small.

(2) The catalyst product has the characteristics of flexibility, light weight, fluffy shape and not easy to break, and can be directly applied to various filled purification equipment, which can avoid the need for traditional catalysts to be used in filled purification equipment to be pressed into tablets or further processed. The problem of large air resistance and easy falling off of the catalyst caused by loading on other bulky carriers can also avoid the problem of easy breakage of inorganic nanofibers during use.

(3) Since the residual chloride ions (from the precursor chloroplatinic acid) have a great influence on the catalytic activity, the chloride ions must be removed. In the present invention, the method of alkali washing and water washing is used to remove the residual chloride ions without subsequent high-temperature heating The dechlorination process saves energy consumption.

(4) The preparation method has simple process, wide sources of raw materials, low cost, good repeatability, and is suitable for industrialized production.

Description of drawings

Figure 1 is a FESEM photo of the catalyst sample prepared in Example 1 of the present invention.

Fig. 2 is a TEM (a) and a high-resolution TEM (b) photo of the catalyst sample prepared in Example 1 of the present invention.

Fig. 3 is the XPS spectrogram of the catalyst prepared in Example 1 of the present invention.

Fig. 4 is a graph showing the results of formaldehyde oxidation activity at room temperature of the catalyst of Example 1 of the present invention, specifically a graph showing the variation of formaldehyde concentration with reaction time.

Detailed ways

The inventors of the present invention will be further described below in conjunction with specific embodiments of the present invention, but the protection scope of the present invention is not limited to these embodiments. All changes or equivalent substitutions that do not depart from the concept of the present invention are included in the protection scope of the present invention.

Example 1

(1) First, dissolve butyl titanate in absolute ethanol, add acetylacetone, stir to form a transparent solution, then add dropwise to an acidic (pH=2) aqueous solution containing 0.01% PVA, and stir for 6 days to obtain a stable solution TiO ₂ sol, wherein the molar ratio of water, absolute ethanol, acetylacetone and butyl titanate is =100:2:0.5:0.5.

(2) Soak the absorbent cotton in the TiO2sol of step (1), the soaking time is 5min, wherein the mass ratio of absorbent cotton and _TiO2 is ₁ :2.0; Dry at 115° C. for 30 minutes, and repeat the above process, but the drying temperature is 60° C., and the drying time is 12 hours to obtain a TiO ₂ /cotton fiber composite base material.

(3) Add complexing agent trisodium citrate to the chloroplatinic acid solution, stir evenly, and disperse the _TiO2 /cotton fiber composite base material obtained in step (2) in the above-mentioned mixed solution and soak for 5min, wherein platinum chloride Acid is 0.5wt% in terms of platinum relative to the quality of _TiO2 /cotton fiber composite base material, then add the alkaline solution of reducing agent potassium borohydride (the pH value is adjusted to about 10 with 0.5M NaOH solution), and the platinum chloride Acid reduction into metal nanoparticles, wherein the molar ratio of chloroplatinic acid, complexing agent and reducing agent is 1:2:30, continue to stir for 5min, then separate the cotton fibers loaded with platinum, and then wash with 0.1M NaOH for 3 and then washed three times with deionized water, and then dried at 60° C. for 12 hours to obtain a Pt/TiO ₂ /cotton fiber room temperature oxidation catalyst.

The FESEM, TEM and XPS spectrogram analysis of the Pt/TiO ₂ /cotton fibers prepared above are shown in Fig. 1, Fig. 2 and Fig. 3 respectively, and it can be seen in Fig. 1 that the Pt/TiO ₂ /cotton fibers are coated with TiO ₂ And before and after loading Pt, the fiber structure is well maintained, wherein the TiO ₂ particle size is between 1-10nm, the coating is evenly loaded on the surface of the cotton fiber, and the noble metal Pt exists in the form of zero-valent simple substance (this is determined by the 71.2eV and 74.8 The two characteristic peaks of eV can be seen) the particle size ranges from 3 to 10nm, and is highly dispersed on the surface of the TiO ₂ coating.

Preparation of embodiment 2 formaldehyde room temperature oxidation catalyst

(1) First, dissolve butyl titanate in absolute ethanol, add acetylacetone, stir to form a transparent solution, then add dropwise to an acidic (pH=2.5) aqueous solution containing 0.05% PVA, and stir for 8 days to obtain a stable solution TiO ₂ sol, wherein the molar ratio of water, acid, absolute ethanol, acetylacetone and butyl titanate = 100:4:0.5:0.5.

(2) Soak the absorbent cotton in the _TiO sol in step (1) for 5 minutes, wherein the mass ratio of cotton to TiO ₂ is 1:2.5, and after being separated by a filter screen, dry it at 60°C for 12 hours to obtain TiO ₂ / Cotton fiber composite base material.

(3) Add complexing agent trisodium citrate to the chloroplatinic acid solution, stir evenly, and disperse the _TiO2 /cotton fiber composite base material obtained in step (2) in the above-mentioned mixed solution and soak for 5min, wherein platinum chloride Acid is 0.25wt% in terms of platinum relative to the quality of _TiO2 /cotton fiber composite base material, then add the alkaline solution of reducing agent potassium borohydride (the pH value is adjusted to about 8 with 0.5M NaOH solution), and the platinum chloride Acid reduction into Pt nanoparticles, wherein the molar ratio of chloroplatinic acid, complexing agent and reducing agent is 1:2:15, continue to stir for 5min, then separate the cotton fibers loaded with platinum, and then wash with 0.1M KOH for 3 and washed three times with deionized water, and then dried at 80°C for 10 hours to obtain a Pt/TiO ₂ /cotton fiber room temperature oxidation catalyst.

Preparation of embodiment 3 formaldehyde room temperature oxidation catalyst

(1) First, dissolve butyl titanate in absolute ethanol, add acetylacetone, stir to form a transparent solution, then add dropwise to an acidic (pH=3) aqueous solution containing 0.01% PVA, and stir for 4 days to obtain a stable solution TiO ₂ sol, wherein the molar ratio of water, absolute ethanol, acetylacetone and butyl titanate = 100:2:0.1:0.1.

(2) Soak absorbent cotton in TiO ₂ sol for 5 minutes, in which the mass ratio of cotton and TiO ₂ is 1:2, after separation by filter screen, dry at 80°C for 10 hours to obtain TiO ₂ /cotton Fiber composite base material.

(3) Add complexing agent trisodium citrate to the chloroplatinic acid solution, stir evenly, and disperse the _TiO2 /cotton fiber composite base material obtained in step (2) in the above-mentioned mixed solution and soak for 5min, wherein platinum chloride Acid is 0.1wt% in terms of platinum relative to the quality of _TiO2 /cotton fiber composite base material, then add the alkaline solution of reducing agent potassium borohydride (the pH value is adjusted to about 8 with 0.5M NaOH solution), and the platinum chloride Acid reduction into Pt nanoparticles, wherein the molar ratio of chloroplatinic acid, complexing agent and reducing agent is 1:2:5, continue to stir for 5min, then separate the cotton fibers loaded with platinum, and wash with 0.2M NaOH for 3 and then washed three times with deionized water, and then dried at 60° C. for 12 hours to obtain a Pt/TiO ₂ /cotton fiber room temperature oxidation catalyst.

Preparation of embodiment 4 formaldehyde room temperature oxidation catalyst

(1) First, dissolve butyl titanate in absolute ethanol, add acetylacetone, stir to form a transparent solution, then add dropwise to an acidic (pH=2) aqueous solution containing 0.01% PVA, and stir for 6 days to obtain a stable solution TiO ₂ sol, wherein the molar ratio of water, absolute ethanol, acetylacetone and butyl titanate = 100:3:0.25:0.25.

(2) Soak the absorbent cotton in TiO ₂ sol for 10 minutes, wherein the mass ratio of cotton and TiO ₂ is 1:3.0, after being separated by a filter, first dry at 60°C for 10 minutes, and then dry at 60°C The time is 12 hours, and the TiO ₂ /cotton fiber composite base material is obtained.

(3) Add the complexing agent trisodium citrate to the chloroplatinic acid solution, stir evenly, and disperse the _TiO2 /cotton fiber composite base material obtained in step (2) in the above-mentioned mixed solution and soak for 10min, wherein the chloroplatinic acid Acid is 0.75wt% in terms of platinum relative to the quality of _TiO2 /cotton fiber composite base material, then add the alkaline solution of reducing agent sodium borohydride (the pH value is adjusted to about 9 with 0.5M NaOH solution), and the platinum chloride Acid reduction into Pt nanoparticles, wherein the molar ratio of chloroplatinic acid, complexing agent and reducing agent is 1:2:15, continue to stir for 5 minutes, then separate the cotton fibers loaded with platinum, and then wash with 0.1M ammonia water for 3 and washed three times with deionized water, and then dried at 100° C. for 6 hours to obtain a Pt/TiO ₂ /cotton fiber room temperature oxidation catalyst.

Preparation of embodiment 5 formaldehyde room temperature oxidation catalyst

(1) First, dissolve tetraisopropyl titanate in absolute ethanol, add acetylacetone, stir to form a transparent solution, then add dropwise to an acidic (pH=2) aqueous solution containing 0.1% PVA, and stir for 6 days A stable _TiO sol was obtained in which the molar ratio of water, absolute ethanol, acetylacetone and tetraisopropyl titanate was = 100:2:0.5:0.5.

(2) Soak absorbent cotton in TiO ₂ sol for 5 minutes, in which the mass ratio of cotton and TiO ₂ is 1:2. After being separated by a filter, first dry at 60°C for 5 minutes, and then dry at 100°C 6h, TiO ₂ /cotton fiber composite base material was obtained.

(3) Add complexing agent trisodium citrate to the chloroplatinic acid solution, stir evenly, and disperse the _TiO2 /cotton fiber composite base material obtained in step (2) in the above-mentioned mixed solution and soak for 5min, wherein platinum chloride Acid is 1.0wt% in terms of platinum relative to the quality of _TiO2 /cotton fiber composite base material, then add the alkaline solution of reducing agent sodium borohydride (the pH value is adjusted to about 10 with 0.5M NaOH solution), and the platinum chloride Acid reduction into Pt nanoparticles, wherein the molar ratio of chloroplatinic acid, complexing agent and reducing agent is 1:2:30, continue to stir for 5min, then separate the cotton fibers loaded with platinum, and then use 0.1M NaOH Wash with KOH mixed solution for 3 times and deionized water for 3 times, then dry at 60° C. for 12 hours to obtain Pt/TiO ₂ /cotton fiber room temperature oxidation catalyst.

The preparation of embodiment 6 formaldehyde room temperature oxidation catalyst

(1) First dissolve tetraisopropyl titanate in absolute ethanol, add acetylacetone, stir to form a transparent solution, then add dropwise to an acidic (pH=2.5) aqueous solution containing 0.1% PVA, and stir for 6 days A stable _TiO sol was obtained in which the molar ratio of water, absolute ethanol, acetylacetone and tetraisopropyl titanate was = 100:2:0.25:0.25.

(2) Soak the absorbent cotton in TiO ₂ sol for 8 minutes, and the mass ratio of cotton to TiO ₂ is 1:2.5. After being separated by a filter, first dry it at 60°C for 5 minutes, and then dry it at 120°C. The time is 4 hours, and the TiO ₂ /cotton fiber composite base material is obtained.

(3) Add the complexing agent EDTA in the chloroplatinic acid solution again, stir evenly, the _TiO2 /cotton fiber composite base material obtained in the step (2) is dispersed in the above-mentioned mixed solution and soaked for 8min, wherein the chloroplatinic acid is mixed with platinum Meter is 2.0wt% with respect to the quality of _TiO2 /cotton fiber composite base material, then add the alkaline solution of reducing agent sodium borohydride (the pH value is adjusted to about 9 with the NaOH solution of 0.5M), the chloroplatinic acid is reduced into Pt nanoparticles, wherein the molar ratio of chloroplatinic acid, complexing agent and reducing agent is 1:2:25, continue to stir for 5min, then separate the cotton fibers loaded with platinum, and then use 0.05M NaOH, KOH and The mixed solution of ammonia and water was washed 3 times, and deionized water was washed 3 times, and then dried at 110°C for 4 hours to obtain a Pt/TiO ₂ /cotton fiber room temperature oxidation catalyst.

Preparation of embodiment 7 formaldehyde room temperature oxidation catalyst

(1) First, dissolve tetraisopropyl titanate in absolute ethanol, add acetylacetone, stir to form a transparent solution, then add dropwise to an acidic (pH=2) aqueous solution containing 0.25% PVA, and stir for 4 days A stable _TiO sol was obtained in which the molar ratio of water, absolute ethanol, acetylacetone and tetraisopropyl titanate was = 100:2:0.1:0.1.

(2) Soak absorbent cotton in TiO ₂ sol for 5 minutes, in which the mass ratio of cotton and TiO ₂ is 1:2.6, after being separated by a filter, dry at 60°C for 4 minutes, and then at 115°C for a drying time Repeat the above process once for 30 minutes, and finally dry at 110°C for 4 hours to obtain a TiO ₂ /cotton fiber composite base material.

(3) Add complexing agent EDTA in the chloroplatinic acid solution again, stir evenly, the _TiO2 /cotton fiber composite base material obtained in the step (2) is dispersed in the above-mentioned mixed solution and soaked for 5min, wherein chloroplatinic acid is mixed with platinum Meter is 0.25wt% relative to the quality of _TiO2 /cotton fiber composite base material, then add the alkaline solution of reducing agent sodium borohydride (the pH value is adjusted to about 10 with the NaOH solution of 0.5M), the chloroplatinic acid is reduced into Pt nanoparticles, wherein the molar ratio of chloroplatinic acid, complexing agent and reducing agent is 1:2:15, continue to stir for 5min, then separate the cotton fibers loaded with platinum, and then wash 3 times with 0.1M KOH to remove Washing with ion water for 3 times, and then drying at 60° C. for 12 hours to obtain a Pt/TiO ₂ /cotton fiber room temperature oxidation catalyst.

In order to investigate the catalytic oxidation degradation effect of the catalyst prepared by the present invention on the degradation of formaldehyde at room temperature, the inventors tested its performance on degradation of formaldehyde at room temperature according to the following method. The test process is as follows: Take 0.3g of the catalyst and spread it on the surface of a watch glass with a diameter of 14cm, cover the glass cover, and then place the watch glass with the catalyst attached in a 5.9L plexiglass reactor, and place a 5W glass reactor at the bottom of the reactor. Then inject a certain amount of concentrated formaldehyde solution into the reactor, turn on the fan, and remove the glass cover until the formaldehyde volatilizes until the concentration is balanced. At this time, the catalyst and formaldehyde start to contact and react. The analyzer (INNOVA air Tech Instruments Model 1412) monitored the concentration changes of formaldehyde and product carbon dioxide online.

The 60min activity data of the catalysts prepared in Examples 1-7 are shown in Table 1. It can be seen from Table 1 that the catalysts of the present invention have good catalytic activity under the condition of relatively low Pt loading.

Table 1

In addition, for investigating the reusability of the catalyst of the present invention, the catalyst sample of Example 1 is reused 4 times, and its reproducibility is observed. The results are shown in Table 2. As can be seen from Table 2: the catalyst of the present invention is used repeatedly. During the process, the activity remains basically unchanged, indicating that the activity of the catalyst of the present invention is stable.

Table 2

Claims (3)

1. a flexible platinum formaldehyde room temperature oxidation catalyst, is characterized in that: this catalyst comprises cotton fiber carrier, _TiO Surface coating and is dispersed in _TiO The Pt active component of coating surface; The preparation method step of described catalyst is as follows: (1) Dissolve titanium alkoxide in absolute ethanol, add acetylacetone, stir to form a transparent solution, then add dropwise to the acidic aqueous solution containing PVA, stir for 4-8 days to obtain a stable TiO ₂ sol; The content of the PVA in water is 0.01-0.1%, wherein the molar ratio of water, absolute ethanol, acetylacetone and titanium alkoxide is 100:2-4:0.1-0.5:0.1-0.5; The titanium alkoxide is one or a mixture of tetraisopropyl titanate and tetrabutyl titanate; (2) Soak the cotton fiber in the TiO ₂ sol in step (1) for 5-10 min, and the mass ratio of cotton fiber to TiO ₂ is 1:2-3. After soaking, the filter screen is separated and dried , to obtain TiO ₂ /cotton fiber composite base material; The drying conditions are as follows: first dry at 50-70 ^o C for 3-10 minutes, then at 110-120 ^o C for 20-40 minutes, repeat the above coating process 1-2 times, and the last drying Temperature 60-110 ^o C, drying time 4-12 hours; (3) Disperse the TiO ₂ /cotton fiber composite base material in step (2) in the mixed solution containing chloroplatinic acid and complexing agent and soak for 5-10 min, wherein chloroplatinic acid accounts for 10% of TiO ₂ / 0.25-2wt% of the cotton fiber composite base material, and then add an alkaline solution of a reducing agent to reduce Pt into metal nanoparticles, wherein the molar ratio of chloroplatinic acid, complexing agent and reducing agent is 1:2:5-30 , continue to stir for 5-10 min, then separate the composite fiber deposited with Pt from the solution, and then wash with alkali and water several times to remove residual chloride ions on the surface, and finally dry at 60-110 ^o C for 4-24 h to obtain Pt/TiO ₂ /Cotton Fiber Composite Formaldehyde Oxidation Catalyst at Room Temperature, The cotton fiber carrier is defatted cotton fiber; The _TiO2 coating is a nano-titanium dioxide coating, which is evenly loaded on the surface of the cotton fiber, and the particle size is between 1-10nm; The Pt exists in the form of zero valence, the particle size range is 1-10 nm, and the loading amount is 0.25-2 wt %. 2. A flexible platinum-formaldehyde room-temperature oxidation catalyst according to claim 1, characterized in that: the acidic substance in the acidic aqueous solution of PVA described in step (1) is one or both of nitric acid and sulfuric acid; The pH of the acidic aqueous solution of PVA is between 2.0-3.0. 3. A flexible platinum-formaldehyde room temperature oxidation catalyst according to claim 1, characterized in that: the complexing agent described in step (3) is one of trisodium citrate and disodium edetate or both; The reducing agent is one or both of potassium borohydride and sodium borohydride; The alkali washing is washing with any aqueous solution of NaOH, KOH and ammonia or a mixture of two or three of them.