WO2003043732A1

WO2003043732A1 - Supported gold catalyst useful for catalytic oxidation of co at low temperature

Info

Publication number: WO2003043732A1
Application number: PCT/CN2001/001582
Authority: WO
Inventors: Lidun An; Shixue Qi; Xuhua Zou; Zhanghuai Suo
Original assignee: Lidun An; Shixue Qi; Xuhua Zou; Zhanghuai Suo
Priority date: 2001-11-23
Filing date: 2001-11-23
Publication date: 2003-05-30
Also published as: AU2002221503A1

Abstract

The present invention provides a kind of supported gold catalyst useful for catalytic oxidation of CO at low temperature. The said catalyst possesses highly catalytic activity at low temperature, and there is no possibility of poisoning of the said catalyst in the presence of moisture or sulfur-containing compound gases. The said catalyst may remain its catalytic activity after long shelf time, and the said catalyst may be reused. The present invention employs Au as active component, and A12O3 (or CO3O4 TiO2/oxide of non-transition metal) as support. The present invention can be used in the catalytic CO oxidation at the ambient temperature and ambient humidity. As the case of the concentration of CO in feed gas is 1.0%, the permeation concentration of CO is less than 94 ppm after the feed gas having passed through the said catalyst 300 min. The said catalyst may be used in the devices for eliminating CO such as gas mask or to purge the room air. Also, the treatment processes of the said catalyst are different from the other treatment processes described in the prior patents, and the resulting catalyst of present invention processes exhibits improved property.

Description

Supported gold catalyst for low-temperature catalytic oxidation of CO

Technical field

The invention relates to a chemical catalyst, in particular to a practical supported gold catalyst that catalyzes the oxidation of trace amounts (0.01% ~ 1.0%) of CO into co _{2 in the} air at ambient temperature and humidity, and the pressure drop meets the requirements of gas masks. . Background technique

CO is the primary pollutant in many industrial environments and indoor ambient air, especially deadly poisons in the air such as fierce battlefields, fire scenes, mine tunnels and the like. Because the binding capacity of CO to human hemoglobin is 250 times that of oxygen, it can prevent hemoglobin from delivering absorbed oxygen to human tissues. The presence of 10 ppm CO in the air has a toxic effect on the human body, and the short-term tolerance of the human body is only 300 ppm. Its harm to human health has long attracted scientists' attention (Stewart, R., The effect of Carbon Monoxide on Humans; Annu Rev. Pharmacol, 1975, 15, 409-423). The results of studies on the adverse effects of low concentrations of CO widely present in ambient air and long-term exposure to such low concentrations (ppm) of CO on human health (Greak, WP, et al., Environ. Sci. Tehnol, 1990, 20, 32-33) has drawn attention to methods for controlling the concentration of CO in ambient air.

Compared with other methods, such as adsorption, CO catalytic oxidation has absolute advantages in terms of equipment volume and ease of operation (Yaparpalvi, R. And Chuang K. T., Ind. Eng. Chem. Res., 1991, 30, 2219- 2225

The catalytic oxidation method refers to the catalytic oxidation reaction between CO and oxygen (o ₂ ) in the air at ambient temperature to generate co _2:

CO + 1/20 ₂ ^{cata] s} ^ C0 ₂ + 2.82E04 J / mol In recent years, the most studied CO oxidation catalysts are supported noble metal catalysts related to automobile exhaust purification (Cooper, BJ, Platinum Metals Rev., 1994, 38 [3]: 101-111). The reaction temperature is generally above 200 ° C. However, it is often necessary to eliminate low concentrations of CO in the air, such as gas masks, indoors (workshops, spacecraft, submarines, rooms, shops, etc.), air purification, etc., which must be Must be performed at ambient temperature and humidity. This requires the catalyst not only to have extremely high low-temperature activity, but also to have good enough stability when the relative humidity is close to 100%.

At present, gas masks often use Hopcalilte catalysts, which are CuO-MnOx-based composite oxide catalysts (Lamb, AB, Bray, WC, Frazer, JCW; Ind. Eng. Chem., 1920, 12, 213). The gas mask catalyst material that has been used in the First World War has a fatal shortcoming that it is poor in water resistance. Therefore, a larger and heavier "drying tank" must be added before the "oxidation tank".

The CO low-temperature oxidation catalysts studied in the laboratory include: (1) Transition metal oxide series. Such as Co ₃ 0 ₄ , Mn0 ₂ , Co ₂ 0 ₃ (Pitzer, E. C "Frazer, JCW, J. Phys. Chem., 1941, 45, 761), and other metal oxide series (Yung Fang, Yu Tao , J: Catal, 1974, 3 , 108) (2) oxide-supported e.g. CoO _x / Ti0 ₂ catalyst (Moshida, I., et al, J. Phys Chem, 1985, 89, 5439..... ) High activity for CO oxidation at room temperature, but the catalyst deactivates quickly after 15 minutes, and has the same poor water resistance as the type (1) catalyst. (3) Supported precious metal catalysts, such as Pd / Fe ₂ 0 ₃ (Pavlova, SN, et al., React. Kinet. Catal. Lett., 1996, 59 [1], 103- 110), Pt / Sn0 ₂ (Li Shiyao, Li Beilu, React. Kinet. Catal. Lett , 1997 ₃ 62 [1], 151-156), Pt (or Pd) / Al ₂ 0 ₃ (Shannon, MD, et al "WO 90/10394), Pt / oxide (Schlatter, J. C" et al WO 90/04930), Pt-Ir / SDB (Styrene-Divinyl-benzene Copolymer)

(Yaparpalvi, R. And Chuang KT, Ind. Eng. Chem. Res., 1991, 30, 2219-2225). These catalysts are too expensive (Li Chunhua, Allington, etc., Environmental Chemistry, 1992, 13 [3], 37) or the reaction temperature is too high (such as Pt-Pt / Al ₂ 0 _3, etc.), or the appropriate CO concentration is too low (Such as Pt-Ir / SDB) and cannot be promoted. Heterogeneous Wacker catalysts (PdCl ₂ -CuCl ₂ etc.) have a high activity for CO oxidation near 60 ° C, but can only work if water is present (Desai, MN, Butt, JB, J. Catal, 1983, 79, 95). (4) Supported gold catalyst. Haruta et al. Found that oxide-supported gold catalysts such as Fe ₂ 0 ₃ , NiO, Ti0 ₂ have high activity for CO oxidation at room temperature (Hamta, M. Yamada, N., J. Catal., 1989, 115, 301) However, its preparation methods are mostly limited to co-precipitation methods UP 92-3712228, JP 92-281846; An Lidun, Hao Zhengping, Chinese invention patent, CN 1125638; Hao Zhengping, An Lidun et al., Chin. Chem. Lett, 1995, 6 ( 4), 345 and 6 (5), 447; Keact. Kinet. Catal.lett, 1996, 59, 259), the powder samples obtained have poor strength and are difficult to put in Practical application. Hamta et al. Used a deposition-precipitation (DP) method or a method in which DP was added with a liquid-phase reducing agent (USP 4839327; USP 4937219) to prepare a granular or honeycomb supported gold catalyst for hydrocarbons. Oxidation reaction with CO and reduction reaction of NOx, but only A _U / F _¾ 0 ₃ -A1 ₂ 0 ₃ catalyst (see USA 4839327, Example 8) that can be used as a gas mask catalyst material, and The activation treatments are all calcined in the air at 200 ~ 400 ° C to decompose Au (OH) ₃ into immobilized, highly dispersed gold (Au ^Q ). Falke (USA 5068217) emphasized that only a gold catalyst supported by a carrier containing Fe ₂ 0 ₃ or a composite oxide carrier (also activated by calcination in air at 200 ~ 400 ° C) has the ability to oxidize CO in humid air at room temperature. Catalytic performance. Summary of the Invention

The purpose of the present invention is to find a kind of catalytic oxidation CO at high ambient temperature (-10 ° C ~ 40 ° C) and ambient humidity (relative humidity 0 ~ 100%) with high reactivity, stable performance, and pressure drop to meet the practical requirements of gas masks. New catalyst.

To this end, the present invention provides a supported gold catalyst for low-temperature CO elimination, which is characterized in that the active component is gold and the carrier is A1 ₂ 0 ₃ (or Co ₃ 0 ₄ , Ti0 ₂ , Ti0 ₂ / non-transition metal oxidation). Catalyst), the atomic ratio of Au to A1 (or Co, Ti) is 1.0: 10 ~ 1.0: 1.0X 10 ³ , and the support of the catalyst may be a shaped oxidation support. The preparation method adopts a deposition-precipitation method or a co-precipitation method, and the activation treatment of the catalyst is a method of reduction with hydrogen or roasting and decomposition. This CO-removing catalyst can be used at ambient temperature (-10 ° C; ~ 40Ό) and ambient humidity. It is stable in activity and can be directly applied to CO-removing devices such as gas masks. Air drying device.

Compared with the prior art, the present invention has the following essential features:

(1) carrier-supported gold catalyst is free of Fe ₂ 0 ₃ of A1 ₂ 0 ₃ (or Co ₃ 0 _4, Ti0 _2,

Ti0 ₂ / non-transition metal oxide), the catalyst is activated by hydrogen reduction or roasting decomposition method.

(2) a catalyst not only has good low-temperature catalytic activity for CO oxidation catalyst into C0 _2, but also has good water vapor intoxication properties, the relative humidity in the range of 0 to 100%, active stabilization, the catalyst bed can be saved Go to the drying jar. (3) The catalyst is granular, and its particle size and mechanical strength ensure that the pressure drop and impact resistance of the bed can meet the practical requirements of gas masks.

(4) Good anti-sulfur poisoning ability.

The invention is described in more detail below:

The active component of the catalyst of the present invention is gold, and the support may be one of A1 ₂ 0 ₃ , Co ₃ 0 ₄ , Ti0 ₂ , Ti0 ₂ / Si0 ₂ or Ti0 ₂ / Al ₂ 0 ₃ .

The precursor compounds of the above active component gold may be metal gold (filament, bar, block), chloroauric acid (HAuCl ₄ · H ₂ 0), gold trichloride (AuCl ₃ ), and the like.

The precursor compounds of the support may be nitrates, sulfates, acetates, chlorides or metal alkoxides of the corresponding oxides, or formed oxides.

When the catalyst used in the present invention is supported by A1 ₂ 0 ₃ (or Co ₃ 0 ₄ , Ti0 ₂ , Ti0 ₂ / Al ₂ 0 ₃ ), the atomic ratio of Au to A1 (or Co, Ti, etc.) is 1.0: 10 ~ 1.0: The range of 1.0 X 10 ³ , Au and A1 (or Co, Ti, etc.) atoms is preferably 1.0: 200 to 1.0: 400.

The preparation method of the catalyst used in the present invention may be a deposition-precipitation method or a co-precipitation method.

The catalyst deposition-precipitation method can be prepared as follows: the oxide support having a high specific surface area formed in advance is vacuum-dried and placed in an active component precursor solution at a controlled temperature (for example, 350K) under continuous stirring Add an alkaline solution (such as Na ₂ C0 ₃ , K ₂ C0 ₃ , NaOH, KOH, etc.) dropwise, and control the pH of the solution at a constant temperature of 4.5 ~ 8.5 until the precipitation is complete. After sedimentation, filtration, washing, drying, and hydrogen Reduction treatment or calcination in the stream yields the finished catalyst.

The preparation process of the catalyst co-precipitation method may be: adding an appropriate amount of a gold salt solution and a salt solution of a support metal to a Na ₂ C0 ₃ (or K ₂ C0 ₃ ) solution dropwise while stirring (or the reverse dropwise order), The desired catalyst can be obtained by standing, separating, roasting or reducing and activating in a hydrogen stream.

The detection method in the following examples of the present invention is to evaluate the performance of the catalyst on the catalytic oxidation reaction of CO on an atmospheric fixed-bed reactor. The composition of the feed gas used is: CO: 0.25% to 1.0%, and the rest is air. The conversion rate of CO was determined from the results of gas chromatography analysis, and the minimum detectable amount of CO was 50 ppm. Part of the catalyst was tested on the CO protective performance test device of the Testing Center of Shanxi Xinhua Chemical Plant in accordance with the requirements of gas mask use standards. The composition of the raw material gas is: CO: 0.25% ~ 1.0%, the air is a balanced gas, and the controlled humidity is a saturated humidity at 23 ° C. detailed description

Example 1: Preparation of a catalyst by a deposition-precipitation method, adding 1.0 g of A1 ₂ 0 ₃ spherical support into water, adjusting the pH value to 7.5 with a 1M NaOH solution under stirring, heating and maintaining the temperature at 70 ° C, and then Add 1.04ml of chloroauric acid solution (9.7200gAu / L) dropwise, and maintain pH = 7.5 with 1M NaOH solution. After reacting for 1h, filter and wash, dry at 60 ° C for 12h, and then reduce at 300 ° C in a hydrogen atmosphere. lh, an Au / Al ₂ 0 ₃ catalyst having an atomic ratio of Au to A1 of 1: 200 was obtained. The finished product was granular and dark brown.

When the composition of the feed gas is: CO: 1%; 0 ₂ : 12%; N ₂ : 87% (volume percentage), and the volumetric space velocity of the gas is ¹ ^ × ΙΟ ⁴ !! · ¹ , CO is completely converted (residual CO is less than the detection limit by gas chromatography 50ppm) to the lowest allowable C0 ₂ reaction temperature (referred to as "minimum full-transition temperature", hereinafter the same) of up to - 15 ° C (258K).

Example 2: The catalyst was prepared by the deposition-precipitation method in Example 1. 1.0 g of TiO ₂ support was added to water, and the pH was adjusted to 5.0 with a 1M NaOH solution under stirring. The temperature was maintained at 70 ° C, and then chlorine was added dropwise. Auric acid solution (9.7200 gAu / L) 1.04ml, and 1M NaOH solution was used to maintain pH = 5.0. After reaction for 1h, it was filtered, washed, dried at 60 ° C for 12h, and then reduced under hydrogen atmosphere at 100 ° C for 1h. The 11/110 ₂ catalyst having an atomic ratio of Au to Ti of 1: 250, and the finished product is light brown.

Using the feed gas described in Example 1 under the same operating conditions, the minimum total conversion temperature of CO is-10 ° C (263K).

Example 3: Au / Al ₂ 0 ₃ catalyst prepared by using the deposition-precipitation method of Example 1 with an atomic ratio of Au to Al of 1: 200. The finished product is granular and dark brown.

The composition of the raw material gas is: CO: 1.0%; the air is a balanced gas, the relative humidity is 100% (23 ° C), and the specific speed is: 0.75L / cm ² .min, tested with a CO protective performance test device, continuous reaction 300 In minutes, the CO transmission concentration is lower than 94ppm (standard requirement: <100ppm), the inhalation resistance after 30L test is 159Pa (standard requirement: 350Pa), and the inhalation resistance after 85L test is 682Pa (standard requirement: 880Pa).

Example 4: The Au / Al ₂ 0 ₃ catalyst having an atomic ratio of Au to Al of 1: 200 prepared by the deposition-precipitation method of Example 1 is granular and has a dark brown finished product.

The composition of the raw material gas is: CO: 0.25%; the air is a balanced gas, and the relative humidity is 100% (23 ° C), Than the speed of: 0.75L / _C _m m in, to test the CO 3 in protective performance test apparatus embodiment, a continuous reaction was ¹²⁰ minutes, through the CO concentration is less than 29ppm. (Standard: <100ppm), 30L test The rear suction resistance is 184Pa (standard requirement: 350Pa), and the 85L test suction resistance is 768Pa (standard requirement: 880Pa).

Example 5: The Au / Al ₂ 0 ₃ catalyst having an atomic ratio of Au to Al of 1: 200 prepared by the deposition-precipitation method of Example 1 is granular and has a dark brown finished product.

The composition of the raw material gas is: CO: 1.0%; the air is a balanced gas, the relative humidity is 100% (23 ° C), and the specific speed is: 1.0 L / cm ² -min, and tested with the CO protective performance test device described in Example 4 ， Continuous reaction for 120 minutes, CO permeation concentration is lower than 158ppm, and the inhalation resistance after the 30L test is 241Pa (standard requirement: 350Pa).

Example 6: (1) The Au / Co ₃ 0 ₄ catalyst having an atomic ratio of Au to Co prepared by the above co-precipitation method of 1: 250, and the finished product was uniform black.

When the raw material gas and gas volumetric space velocity described in the use case 1 is 7.5 × 10 ³ }!- ¹ , the minimum total conversion temperature of CO is -18 ° C.

Example 7: The raw material gas described in Example 1 was compounded with 15 ppm H ₂ S. The catalyst described in Example 1 was tested for sulfur poisoning resistance. At room temperature, the CO catalytic oxidation reaction was continuously performed for 120 min. The catalyst had no reactive activity. Detectable change, no detectable CO concentration in tail gas.

Example 8: A1 ₂ 0 _{3 was} immersed in a sol prepared with butyl titanate, and filtered and dried at 500 ° C. for 1 h to obtain a Ti0 ₂ -A1 ₂ 0 ₃ composite support. The precipitation method prepared a catalyst with a loading of 1.0 wt% Au / TiO ₂ —Al ₂ O ₃ , and the finished product was uniform light brown.

When the raw material gas and gas volumetric space velocity described in Example 1 are XIO ³ ! ^, The minimum total CO conversion temperature is -35 ° (:.

Example 9: A catalyst was prepared by a deposition-precipitation method. A 1.0 g spherical support of 1.0 g A1 ₂ 0 _{3 was} added to water, and the pH was adjusted to 7.5 with a 1M NaOH solution under stirring, and the temperature was maintained at C, and then dropwise. Add 1.04 ml of chloroauric acid solution (9.7200 g Au / L), and maintain pH = 7.5 with 1M NaOH solution. After reacting for 1 h, filter, wash, dry at 60 ° C for 12 h, and then roast at 350 ° C for 2 h in air atmosphere. An Au / Al ₂ 0 ₃ catalyst having an atomic ratio of Au to A1 of 1: 400 is obtained, and the finished product is granular and has a dark brown color. When the composition of the raw material gas is: CO: 1%; 0 ₂ : 12%; N ₂ : 87% (volume percentage), and the volumetric space velocity of the gas is 1.5 X lO ¹ , the minimum total conversion temperature of CO can reach -15 ° C (258K) o Example 10: The catalyst was prepared by the deposition-precipitation method of Example 1, 1.0 g of Ti0 ₂ support was added to water, and the pH was adjusted to 5.0 with a 1M NaOH solution under stirring, and the temperature was maintained at 70 ° C. Then, 1.04 ml of a chloroauric acid solution (9.7200 g Au / L) was added dropwise, and the pH was maintained at 5.0 with a 1M NaOH solution. After reacting for 1 hour, it was filtered, washed, and dried at 60 ° C for 12h. Then, it was dried at 320 ° C under air atmosphere. C was calcined for 1 h, and a 1/110 ₂ catalyst having an atomic ratio of Au to Ti of 1: 250 was obtained, and the finished product was light brown.

Example 11: The finished catalyst prepared in Example 9, placed in the presence of a desiccant in the air a year or more, as the feed gas _{composition: CO: 1%; 0 2} : 12%; N 2: 87% (Volume percentage), when the gas volumetric space velocity is 1.5 X 10 ⁴ h, the minimum total conversion temperature of CO can still reach-15 ° C (258K), and its catalytic activity is the same as that of fresh catalyst.

Example 12: Example 9 Preparation of the finished catalyst was then placed in the air for six months or even longer, as the feed gas _{composition: CO: 1%; 0 2} : 12%; N 2: 87% ( volume percent), In the case of a gas volumetric space velocity of 1.5 × 10 ⁴ !! · ¹ , the minimum full conversion temperature of CO can still reach -15 ° C (258K), and its catalytic activity is the same as that of fresh catalyst.

Example 13: After the catalyst used in the test in Example 3 was left in the air for 6 months, 60 ml (half the amount of the catalyst used in Example 3) was taken and tested using the CO protective performance test device described in Example 3. The composition is: CO: 0.25%; air is equilibrium gas, air temperature is 25 ° C, relative humidity is 97%, specific speed is: 0.75L / cm ² .min, continuous reaction for 60 minutes, CO permeation concentration is lower than 10ppm, 85L Inhalation resistance after test is 330 Pa (standard requirement: 880Pa).

Claims

Rights request

1. A supported gold catalyst for CO low-temperature catalytic oxidation, characterized in that the active component is gold, and the carrier is A1 ₂ 0 ₃ or Co ₃ 0 ₄ , Ti0 ₂ , Ti0 ₂ / non-transition metal oxide, Au and A1 Or the atomic ratio of Co or Ti is 1.0: 10—1.0: 1.0 X 10 ³ c

2. The supported gold catalyst for low-temperature catalytic oxidation of CO according to claim 1, characterized in that the atomic ratio of Au to A1 or Co or Ti is 1.0: 200 to 1.0: 400.

3, 1 or 2 of said supported gold catalysts for low-temperature CO oxidation catalyst according to claim, characterized in that the supported catalyst may be formed with an oxide or modified T i0 ₂ shaped oxide support.

4. The supported gold catalyst for low-temperature catalytic oxidation of CO according to claim 1, characterized in that said non-transition metal oxide is A1 ₂ 0 ₃ or Si0 ₂ .

5. The supported gold catalyst for low-temperature catalytic oxidation of CO according to claim 1, characterized in that it can be used at an ambient temperature of -10 ° C to 40 ° C and an ambient humidity (RH is 0 to 100%). It has stable activity and long-term storage in ambient air without affecting catalytic activity. It can be directly applied to CO-eliminating devices such as gas masks, and the drying tank in front of the catalyst bed is eliminated.

6. A method for preparing a supported gold catalyst for low-temperature catalytic oxidation of CO according to claim 1, characterized in that it is prepared by a deposition-precipitation method or a co-precipitation method, wherein the active group The partial solution is added dropwise to a carrier suspension whose pH value is adjusted by an alkali solution, and the activation treatment of the catalyst is performed by flowing hydrogen reduction or calcination in air.

7. The method according to claim 6, characterized in that the preparation process of the deposition-precipitation method is: the activity of the oxide support having a high specific surface area formed in advance under vacuum control after being subjected to vacuum drying treatment In the component precursor solution, the alkaline solution is added dropwise during continuous stirring, and the pH value of the solution is controlled at a constant temperature of 4.5 to 8.5 until the precipitation is complete. After sedimentation, filtration, washing, drying, reduction treatment in a hydrogen stream or roasting Decomposition gives the finished catalyst.

8. The method according to claim 6, characterized in that the preparation process of the co-precipitation method may be: adding an appropriate amount of a gold salt solution and a salt solution of a carrier metal to N¾C0 ₃ or (: 0 _{3) while} stirring. The required catalyst can be obtained from the solution, or in the reverse dropwise order, by standing, separating, roasting or reducing and activating in a hydrogen stream.